Optical and electrical signal transmission composite cable and method for manufacturing the same

Abstract

The present application relates to the technical field of photoelectric composite cable, and discloses a photoelectric signal transmission composite cable and a preparation method thereof, which comprises, from inside to outside, a photoelectric composite cable core, a reactive slip buffer layer and a flame-retardant hydrolysis-resistant outer sheath. The preparation method comprises the following steps: bundling and twisting the insulated copper wire and the quartz optical fiber, and wrapping the periphery with a polytetrafluoroethylene tape to obtain the photoelectric composite cable core; extruding a premix containing a thermoplastic elastomer and an epoxy siloxane onto the outside of the cable core to form the slip buffer layer; dispersing and blending the outer sheath raw material through a double-screw extruder and granulating; and finally, single-screw melt extruding the sheath material onto the outside of the buffer layer and cooling and setting. The present application uses an interface slip layer in cooperation with a flame-retardant hydrolysis-resistant sheath to weaken the optical fiber micro-bending attenuation caused by deformation extrusion, thereby improving the long-term stability of the photoelectric signal transmission composite cable in a humid and hot environment.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic composite cable technology, specifically to an optoelectronic signal transmission composite cable and its preparation method. Background Technology

[0002] Cables are the fundamental physical medium for energy transfer and data exchange in modern equipment. Optoelectronic signal transmission technology mainly integrates quartz optical fibers with broadband data transmission capabilities with metal conductors responsible for transmitting electrical energy and low-frequency signals, enabling a single cable structure to simultaneously complete high-speed optical communication and basic power supply.

[0003] In applications such as medical imaging equipment, endoscopes, surgical robots, and other reusable sterilizable medical devices, moving parts often need to be repeatedly bent or moved within confined spaces. Furthermore, the cables involved often require repeated high-temperature steam sterilization treatment at approximately 134°C after clinical use. Therefore, the cables must not only have a small outer diameter but also possess flexibility, bending resistance, resistance to damp heat aging, and stable optical transmission capabilities. For this purpose, optical fibers and insulated copper conductors are typically housed together within a polymer sheath, forming a composite optical cable suitable for dynamic wiring and repeated sterilization environments.

[0004] Existing polyurethane-sheathed optoelectronic composite cables still have shortcomings in high-temperature, high-humidity, or frequent temperature change environments. Polyurethane materials are prone to hydrolysis under humid and hot conditions, leading to molecular chain breakage and a decline in mechanical properties. Some flame-retardant fillers added to meet flame-retardant requirements may also promote polyurethane chain degradation due to their acidic sites or hygroscopic interfaces, thereby shortening the service life of the sheath material.

[0005] Furthermore, during high and low temperature alternation, the difference in thermal expansion between the sheath material and the internal optical fiber and metal conductor can easily lead to the accumulation of interfacial stress. This stress can exert radial pressure on the silica optical fiber, causing micro-bending and resulting in additional transmission loss. As the number of cycles increases, the optical signal attenuation may further worsen, affecting the long-term stability of the equipment.

[0006] Therefore, this invention proposes a composite cable for photoelectric signal transmission and its preparation method to overcome the shortcomings of the prior art. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a composite cable for photoelectric signal transmission and its preparation method, which solves the problems of catalytic hydrolysis in existing polyurethane sheathed photoelectric composite cables under long-term humid and hot environments, and micro-bending attenuation of internal optical fibers caused by sheath deformation and extrusion under thermal cycling conditions.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] In a first aspect, the present invention provides a composite cable for transmitting photoelectric signals, employing the following technical solution:

[0010] A composite cable for photoelectric signal transmission includes, from the inside out, a composite cable core, a reactive slip buffer layer, and a flame-retardant and hydrolysis-resistant outer sheath. The reactive slip buffer layer is made from the following raw materials in parts by weight: 100 parts by weight of thermoplastic polyurethane elastomer; 3-5 parts by weight of epoxidized soybean oil; and 2-4 parts by weight of epoxy-terminated polydimethylsiloxane. The flame-retardant and hydrolysis-resistant outer sheath is made from the following raw materials in parts by weight: 100 parts by weight of thermoplastic polyurethane elastomer; and 15-20 parts by weight of... Aluminum diethylphosphonate; 10-15 parts by weight of melamine cyanurate; 3-5 parts by weight of epoxidized soybean oil; 2-4 parts by weight of hydroxyl-terminated polydimethylsiloxane; 2-3 parts by weight of anti-hydrolysis agent masterbatch; the optoelectronic composite cable core is used for synchronous transmission of optoelectronic signals, the reactive slip buffer layer is used to provide slip buffer between the optoelectronic composite cable core and the flame-retardant and hydrolysis-resistant outer sheath, and the flame-retardant and hydrolysis-resistant outer sheath is used to provide flame-retardant and hydrolysis-resistant protection for the optoelectronic signal transmission composite cable.

[0011] By adopting the above technical solution, this invention uses a reactive slip buffer layer with a specific ratio and a flame-retardant and hydrolysis-resistant outer sheath for composite coating, which can maintain the mechanical stability of the photoelectric signal transmission composite cable in a long-term hydrothermal environment to a certain extent, and improve the signal attenuation problem under thermal cycling conditions. Its specific mechanism of action is as follows:

[0012] During the blending and extrusion stages of the flame-retardant and hydrolysis-resistant outer sheath, the epoxidized soybean oil in the system primarily utilizes the ring-opening reaction of its epoxy groups to preferentially bind to residual acidic sites on the surface of diethylphosphinate aluminum and melamine cyanurate powders. This process helps mask the acidic catalytic centers on the surface of the flame-retardant powder, reducing the risk of deactivation of the hydrolysis-resistant masterbatch during thermal processing. When the cable is exposed to high-temperature moisture, the polycarbodiimide hydrolysis-resistant component in the active hydrolysis-resistant masterbatch retains carbodiimide groups. These groups can capture the free end carboxyl groups generated by the trace hydrolysis of thermoplastic polyurethane elastomer and undergo an addition reaction. This in-situ capture reaction largely inhibits the autocatalytic degradation pathway of easily hydrolyzed bonds in the polyurethane chain by the carboxyl groups, thereby maintaining the integrity of the polymer macromolecular chain skeleton and macroscopic mechanical strength.

[0013] Furthermore, during the extrusion molding process, the epoxy-terminated polydimethylsiloxane and epoxidized soybean oil inside the reactive slip buffer layer undergo addition reactions with the active end groups of the thermoplastic polyurethane elastomer in adjacent layers under the influence of the thermal field at the extrusion interface, constructing a chemical anchoring structure at the interface. Because the epoxy-terminated polydimethylsiloxane inherently possesses flexible siloxane segments, this structure forms a low-surface-energy molecular-level slip region around the periphery of the optoelectronic composite cable core. This allows the slip layer to homogenize and dissipate deformation stress through the internal rotation and local relative slippage of macromolecular segments when the external ambient temperature fluctuates drastically, causing the sheath layer to shrink or expand. This, in turn, weakens the concentrated transmission of radial extrusion stress to the internal quartz optical fiber.

[0014] Meanwhile, the hydroxyl-terminated polydimethylsiloxane contained in the outer sheath can improve the interfacial compatibility between the flame retardant and the polyurethane matrix to a certain extent, and promotes the accelerated formation of a dense silicon-carbon layer on the surface when exposed to heat during fire. The liquid siloxane and oil components in the formulation system, due to their participation in the aforementioned reactive anchoring, are largely detached from their original free state. This helps to suppress the migration and precipitation of small molecules under long-term operating conditions, maintaining the long-term effectiveness of the flame retardant network.

[0015] Preferably, the reactive slip buffer layer is made of the following raw materials in parts by weight: 100 parts by weight of thermoplastic polyurethane elastomer, 3.5-4 parts by weight of epoxidized soybean oil, and 3-3.5 parts by weight of epoxy-terminated polydimethylsiloxane; the flame-retardant and hydrolysis-resistant outer sheath is made of the following raw materials in parts by weight: 100 parts by weight of thermoplastic polyurethane elastomer, 16-18 parts by weight of aluminum diethylphosphinate, 11-12 parts by weight of melamine cyanurate, 3.5-4 parts by weight of epoxidized soybean oil, 3-3.5 parts by weight of hydroxyl-terminated polydimethylsiloxane, and 2.5-2.8 parts by weight of hydrolysis-resistant masterbatch.

[0016] By adopting the above technical solution, the chemical stoichiometric ratio between the reactants was further adjusted. The appropriate ratio not only facilitates the effective coating of acidic sites on the surface of flame-retardant powder, but also avoids the excessive cross-linking of polyurethane elastomer caused by excessive epoxy components to a certain extent. This allows the material to take into account both the flowability required for extrusion processing and the deformation resilience after cabling.

[0017] Preferably, the anti-hydrolysis agent masterbatch is prepared by melt granulation of solid polymer anti-hydrolysis resin and thermoplastic polyurethane elastomer; the solid polymer anti-hydrolysis resin is prepared by reacting diphenylmethane-4,4'-diisocyanate and 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide in toluene solvent and then extruding to remove the toluene solvent.

[0018] By employing the above-mentioned technical solution, a high-molecular-weight solid hydrolysis-resistant resin is synthesized based on a specific catalytic reaction, and then pre-blended and granulated with a thermoplastic polyurethane elastomer carrier. This pre-dispersed structure typically improves the dispersion uniformity of the hydrolysis-resistant active ingredients within the final outer sheath matrix; simultaneously, the high molecular weight of the resin further limits the volatility and migration tendency of the active ingredients, helping to extend the effective hydrolysis protection period of the composite cable.

[0019] Preferably, the epoxy equivalent of the epoxy-terminated polydimethylsiloxane is 600–2200 g / eq; the epoxy-terminated polydimethylsiloxane is prepared by hydrosilylation reaction of hydrogen-terminated polydimethylsiloxane with a hydrogen mass fraction of 0.05%–0.20% and allyl glycidyl ether under the action of a platinum catalyst, followed by vacuum devolatilization to remove low molecular weight compounds.

[0020] By employing the above technical solution, the epoxy equivalent of the siloxane is limited to a specific range, giving the siloxane molecular chain segments in the slip buffer layer suitable steric hindrance and flexibility. Combined with the de-vaporization process to remove residual low-molecular-weight volatiles, the microporosity defects in the buffer layer induced by the thermal vaporization of low-molecular-weight substances inside the cable can be reduced, thus promoting good structural compactness of the slip layer.

[0021] Preferably, the optoelectronic composite cable core includes a stranded core wire formed by concentrically stranding insulated copper wire and quartz optical fiber, and a basic isolation layer formed by continuously wrapping polytetrafluoroethylene tape around the outside of the stranded core wire; the stranding pitch of the stranded core wire is 30-50 mm; the wrapping overlap rate of the polytetrafluoroethylene tape is 15%-30%; and the thickness of the basic isolation layer is 0.05-0.1 mm.

[0022] By adopting the above technical solution and setting appropriate stranding pitch and wrapping overlap, the insulated copper conductor and the quartz optical fiber tend to maintain a relatively consistent stress release path when subjected to bending stress. The basic isolation layer composed of polytetrafluoroethylene tape provides initial rigid support for the quartz optical fiber. Together with the outer reactive slip buffer layer, it forms a composite stress buffer structure with multi-level modulus gradients, which can, to a certain extent, reduce the risk of thermal damage to the internal sensitive transmission medium caused by the high temperature of external extrusion.

[0023] Secondly, the present invention provides a method for preparing a composite cable for photoelectric signal transmission, which adopts the following technical solution:

[0024] A method for manufacturing a composite cable for photoelectric signal transmission includes the following steps:

[0025] S1: Insulated copper wire and quartz optical fiber are bundled together to obtain a bundled core wire; a polytetrafluoroethylene (PTFE) tape is wrapped around the outside of the bundled core wire to form a basic insulating layer, resulting in an optoelectronic composite cable core; S2: Thermoplastic polyurethane elastomer, epoxidized soybean oil, and epoxy-terminated polydimethylsiloxane are mixed evenly to obtain a buffer layer premix dry material; the buffer layer premix dry material is fed into a first single-screw extruder and extruded into a tube, which is then wrapped around the outside of the optoelectronic composite cable core obtained in S1 to form a reactive slip buffer layer, resulting in a cable core with a buffer layer. Cable core; S3: The raw materials for preparing the flame-retardant and hydrolysis-resistant outer sheath, including the anti-hydrolysis agent masterbatch, are fed into a twin-screw extruder for dispersion and blending, extrusion, pelletizing, dehydration and drying to obtain the flame-retardant and hydrolysis-resistant outer sheath material; S4: The cable core with buffer layer is continuously fed into the center of the die head of a second single-screw extruder, and the flame-retardant and hydrolysis-resistant outer sheath material is fed into the second single-screw extruder for melting, plasticizing and extrusion, covering the outside of the cable core with buffer layer, and after cooling and shaping, the photoelectric signal transmission composite cable is obtained.

[0026] By adopting the above technical solution and utilizing a multi-stage step-by-step extrusion molding process, the molding process for different functional levels is rationally separated. In the initial stage of processing, the single-screw extrusion coats the premixed dry material into a buffer layer, allowing the epoxy component and the elastomer matrix to undergo preliminary melt mixing. Subsequently, in the independent twin-screw blending stage of the outer sheath material, the flame retardant system and the anti-hydrolysis system are pre-dispersed and granulated, which helps to avoid agglomeration defects caused by direct mixing of powder fillers at the terminal extruder head. When the outer sheath material is melted again in the second single screw and coated on the outside of the cable core with the buffer layer, the polymer macromolecules at the contact surface of the two layers undergo segment interpenetration and local cross-linking due to the residual heat of the extrusion interface, thereby constructing a composite protective layer with a relatively tight bond and flexible interface sliding characteristics.

[0027] Preferably, in step S3, the twin-screw extruder is sequentially configured with zone one, zone two, zone three, a natural exhaust section, a vacuum exhaust section, zone four, and a die head along the material conveying direction; step S3 includes: adding a portion of the thermoplastic polyurethane elastomer, aluminum diethylphosphinate, and melamine cyanurate to zone one via the main feeder and conveying it to zone two; when the material enters zone two, injecting the epoxidized soybean oil through the first injection port to form an initial melt mixture in zone two; subsequently, adding the remaining thermoplastic polyurethane elastomer to the initial melt mixture via the first side feeder and conveying it to zone three; when the material enters zone three, injecting hydroxyl-terminated polydimethylsiloxane through the second injection port for mixing and dispersion; when After passing through the natural exhaust section and the vacuum exhaust section in sequence, the material is fed with the anti-hydrolysis agent masterbatch via a second side feeder before entering the metering and conveying section of the fourth zone. The masterbatch then enters the fourth zone and is dispersed and blended within the barrel of the fourth zone, finally being extruded and granulated to obtain the flame-retardant and anti-hydrolysis outer sheath material. The first injection port is located in the second zone, downstream of the first melting and kneading section of the second zone. The feeding position of the first side feeder is located downstream of the first injection port and between the first and second injection ports. The second injection port is located in the third zone. The feeding position of the second side feeder is located after the vacuum exhaust section and before the metering and conveying section of the fourth zone.

[0028] By adopting the above technical solution and relying on the hardware structure of the twin-screw extruder with multiple temperature zones and segmented feeding positions, asynchronous sequential mixing of materials was implemented. This allows some elastomers, flame-retardant powders, and epoxidized soybean oil to initially contact and melt together in the front-end temperature zone, providing ample space and time for the epoxidized soybean oil to preferentially coat and act on the free acidic sites on the surface of the flame-retardant powders. After the initial completion of this surface coating and ring-opening reaction process, the remaining matrix resin and liquid siloxane are added in batches through the side feed and injection port to control the peak mixing viscosity of the system in the early stage. After the material passes through the exhaust section to remove small-molecule volatiles, an anti-hydrolysis agent masterbatch, which is more sensitive to high temperature and high shear, is introduced at the front end of the fourth zone. This moderately shortens the thermal residence period of the carbodiimide groups in the anti-hydrolysis agent masterbatch within the barrel, which can largely maintain its reactivity during subsequent anti-hydrolysis reactions.

[0029] Preferably, in step S2, the barrel temperature of the first single-screw extruder is controlled at 160-180°C, and the thickness of the reactive slip buffer layer is 0.1-0.2 mm; in step S4, the die head of the second single-screw extruder adopts a tube-type die, and the draw ratio is controlled at 1.5-3.0; the extrusion process parameters of the second single-screw extruder are: barrel temperature 140-155°C, die head temperature 150-160°C, and after coating, it is shaped and cooled in a cooling water tank at 15-20°C.

[0030] By adopting the above technical solution, differentiated thermal processing processes were set for the different material systems of the inner and outer layers. The buffer layer uses a relatively high extrusion temperature to obtain excellent melt ductility; while the extrusion of the outer sheath material appropriately lowers the processing temperature range to prevent the anti-hydrolysis agent from decomposing prematurely due to local overheating. At the same time, the extrusion die used in the die head, combined with a specific draw ratio, ensures that the molten tube blank is mainly longitudinally stretched and oriented during traction wrapping and water bath cooling and shaping. This forming method alleviates the radial clamping force applied to the internal sensitive optical fiber during melt cooling and shrinkage to a certain extent, which is conducive to maintaining a low additional attenuation state of the photoelectric transmission channel.

[0031] Preferably, the anti-hydrolysis agent masterbatch is prepared in advance by including the following steps:

[0032] (1) 100 parts by weight of diphenylmethane-4,4'-diisocyanate and 200 parts by weight of toluene are added to a reactor and heated to reflux. 0.5 to 1.0 parts by weight of 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide are added. The reaction is carried out for 4 to 6 hours and the generated carbon dioxide is discharged to obtain a polymeric anti-hydrolysis mixture. (2) The polymeric anti-hydrolysis mixture is extruded and the toluene solvent is removed. After cooling, it is granulated to obtain a solid polymeric anti-hydrolysis resin. (3) 40 to 60 parts by weight of the solid polymeric anti-hydrolysis resin is mixed with 40 to 60 parts by weight of thermoplastic polyurethane elastomer and melt-granulated by a twin-screw extruder to obtain the anti-hydrolysis agent masterbatch.

[0033] By employing the above technical solution, a solution reaction system provides a relatively homogeneous and heat-conducting reaction environment for the formation of a high-molecular-weight hydrolysis-resistant resin containing a carbodiimide structure from diisocyanate, resulting in a relatively concentrated molecular weight distribution in the generated high-molecular-weight hydrolysis-resistant resin. After solvent removal, the secondary melt blending of the solid resin and the polyurethane carrier essentially performs a polymer-level pre-encapsulation treatment of the active hydrolysis-resistant material. This treatment not only weakens the tendency of high-concentration carbodiimide active groups to self-react or deactivate during subsequent storage and secondary processing, but also further improves its dispersion compatibility in the final molded sheath.

[0034] Preferably, the epoxy-terminated polydimethylsiloxane is prepared in advance by including the following steps:

[0035] (1) 100 parts by weight of hydrogen-capped polydimethylsiloxane with a hydrogen mass fraction of 0.05% to 0.20% and 8 to 30 parts by weight of allyl glycidyl ether were added to a reaction vessel for nitrogen purging. After stirring and mixing, the mixture was heated to 80 to 90°C to obtain a silicon-hydrogen reaction mixture premix. (2) 0.5 to 0.8 parts by weight of isopropanol chloroplatinate solution with a platinum mass concentration of 2000 ppm were added to the silicon-hydrogen reaction mixture premix. The mixture was reacted at 85 to 95°C for 3 to 5 hours to obtain crude epoxy silicone oil. (3) The crude epoxy silicone oil was fed into a devolatilization device and devolatilized under reduced pressure at an absolute pressure of 0.008 MPa and a temperature of 110 to 120°C for 2 to 3 hours to obtain the epoxy-capped polydimethylsiloxane.

[0036] By employing the above-mentioned technical solution, a relatively precise hydrosilylation reaction is completed under the guidance of a platinum catalyst, effectively grafting reactive epoxy groups onto the ends of siloxane segments. The subsequent vacuum devolatilization step utilizes the synergistic distillation effect of negative pressure and high temperature to remove, to a large extent, incompletely converted allyl glycidyl ethers and associated low-molecular-weight impurities from the reaction system. This purification process cleanses the final composition of the modified silicone oil, typically reducing the risk of micropores or sheath bulging caused by residual low-boiling-point volatiles during subsequent high-temperature extrusion of cables.

[0037] This invention provides a composite cable for photoelectric signal transmission and its fabrication method. It has the following beneficial effects:

[0038] 1. This invention introduces a segmented feeding process during extrusion, allowing epoxidized soybean oil to preferentially consume acidic sites on the surface of the flame-retardant powder, preventing the deactivation of the polycarbodiimide anti-hydrolysis component during the blending stage. When faced with high-temperature moisture intrusion, the retained active carbodiimide groups can react with the free terminal carboxyl groups generated by the hydrolysis of the polyurethane matrix, inhibiting the autocatalytic pathway of molecular chain degradation. This mechanism effectively maintains the mechanical strength of the composite cable under long-term hydrothermal conditions, ensuring external protection stability during photoelectric signal transmission.

[0039] 2. This invention utilizes a reactive slip buffer layer extruded between the cable core and the sheath, forming a reactive bonding interface between epoxy-terminated polydimethylsiloxane and the matrix during processing. The flexible siloxane segments within the buffer layer impart molecular-level slip properties to the interface. When the composite cable experiences volume shrinkage stress due to alternating high and low temperatures, this slip layer effectively homogenizes and dissipates the deformation stress, reducing the concentration of extrusion stress in the internal optical fiber, thereby ensuring a low-additional attenuation state during thermal cycling of the photoelectric signal transmission channel.

[0040] 3. This invention utilizes the addition reaction between epoxy groups and residual acidic sites or hydroxyl groups within the system to bind and lock low-melting-point liquid components such as epoxidized soybean oil into a polymer network. This alters the free state of the liquid material and inhibits its migration and precipitation to the surface when heated at high temperatures. This structure effectively improves the combustion dripping problem caused by flammable migrations, maintains a stable dispersion network of the main flame retardant within the composite cable, and thus provides reliable halogen-free flame retardant properties for the photoelectric signal transmission medium when the line is subjected to fire hazards. Attached Figure Description

[0041] Figure 1 This is a graph showing the test results of the process retention rate of active groups in the flame-retardant and hydrolysis-resistant outer sheath material of this invention;

[0042] Figure 2 The figures show the test results of extrusion rheology and processing stability of the flame-retardant and hydrolysis-resistant outer sheath material of the present invention; where (a) is the result of the main machine current fluctuation rate, and (b) is the result of the result of the range of melt pressure difference at the die head. Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0045] Thermoplastic polyurethane elastomer, specifically a commercially available polyether-type thermoplastic polyurethane elastomer, has a Shore hardness range of 70A to 80A and a melt flow rate of 15 to 25 g / 10 min at 190°C and 2.16 kg.

[0046] Aluminum diethylphosphonate, CAS number 225789-38-8, with a particle size distribution D50 of 1 to 3 μm, is a powder that has not been pre-coated with silane, melamine cyanurate or resin.

[0047] Melamine cyanurate, CAS number 37640-57-6, with a particle size distribution D50 of 1 to 3 μm.

[0048] Epoxidized soybean oil, CAS number 8013-07-8, with an epoxy value greater than or equal to 6.0% and an iodine value less than or equal to 6.0gI2 / 100g.

[0049] Hydroxyl-terminated polydimethylsiloxane, CAS No. 70131-67-8, with a kinematic viscosity of 1000 to 3000 cSt and a hydroxyl mass fraction of 0.1% to 0.5%.

[0050] Hydrogen-terminated polydimethylsiloxane, CAS number 70900-21-9.

[0051] Allyl glycidyl ether, CAS number 106-92-3.

[0052] The chloroplatinic acid isopropanol solution is prepared by chloroplatinic acid (CAS No. 16941-12-1) and isopropanol (CAS No. 67-63-0), wherein the platinum mass concentration is 2000 ppm.

[0053] Diphenylmethane-4,4'-diisocyanate, CAS number 101-68-8.

[0054] Toluene, CAS number 108-88-3.

[0055] 3-Methyl-1-phenyl-2-phosphacyclopentene-1-oxide, CAS No. 707-61-9.

[0056] See the preparation example for the anti-hydrolysis agent masterbatch.

[0057] See the preparation example for epoxy-terminated polydimethylsiloxane.

[0058] The polytetrafluoroethylene (PTFE) tape is an unsintered PTFE raw material tape product with a thickness of 0.05 to 0.1 mm.

[0059] Quartz optical fiber is a commercially available communication quartz optical fiber with an acrylate coating on the outside.

[0060] The insulated copper wire is a commercially available multi-strand stranded oxygen-free copper wire with a polytetrafluoroethylene insulation layer on the outside.

[0061] Preparation Example 1:

[0062] This preparation example provides a method for preparing epoxy-terminated polydimethylsiloxane, including the following steps:

[0063] Step 1: Add 100 parts by weight of hydrogen-terminated polydimethylsiloxane with a hydrogen mass fraction of 0.20% and 30 parts by weight of allyl glycidyl ether into the reactor, seal the reactor, and purge with nitrogen gas of 99.9% purity or higher for purging. After each purging to 0.2 MPa, purge the gas. Repeat the purging process 3 times, with the purging process taking 15 minutes. Then, start stirring at a speed of 200 r / min and stir continuously for 10 minutes to ensure uniform mixing of the materials. Next, heat the mixture to 80°C to obtain the silicon-hydrogen reaction premix.

[0064] Step 2: Add 0.5 parts by weight of a platinum isopropanol chloroplatinate solution with a mass concentration of 2000 ppm to the silane-hydrogen reaction mixture obtained in Step 1, keep the stirring speed at 200 r / min, control the reaction temperature at 85℃, and continue the reaction for 3 hours to obtain crude epoxy silicone oil.

[0065] Step 3: The crude epoxy silicone oil obtained in Step 2 is fed into a vacuum devolatilization device and devolatilized under reduced pressure of 0.008 MPa and temperature of 110°C for 2 hours to remove unreacted low molecular weight compounds and obtain epoxy-terminated polydimethylsiloxane with an epoxy equivalent of 600 to 680 g / eq.

[0066] Preparation Example 2:

[0067] This preparation example provides a method for preparing epoxy-terminated polydimethylsiloxane, including the following steps:

[0068] Step 1: Add 100 parts by weight of hydrogen-terminated polydimethylsiloxane with a hydrogen mass fraction of 0.12% and 18 parts by weight of allyl glycidyl ether into the reactor, seal the reactor, and purge with nitrogen gas of 99.9% purity or higher for purging. After each purging to 0.2 MPa, purge the gas. Repeat the purging process 3 times, which takes 20 minutes. Then start stirring at a speed of 250 r / min and stir continuously for 15 minutes to ensure uniform mixing of the materials. Then heat the mixture to 85°C to obtain the silicon-hydrogen reaction premix.

[0069] Step 2: Add 0.6 parts by weight of a platinum isopropanol solution with a mass concentration of 2000 ppm to the silane-hydrogen reaction mixture obtained in Step 1, keep the stirring speed at 250 r / min, control the reaction temperature at 90℃, and continue the reaction for 4 hours to obtain crude epoxy silicone oil.

[0070] Step 3: The crude epoxy silicone oil obtained in Step 2 is fed into a vacuum devolatilization device and subjected to vacuum devolatilization under an absolute pressure of 0.008 MPa and a temperature of 115°C for 2.5 hours to remove unreacted low molecular weight compounds, thereby obtaining epoxy-terminated polydimethylsiloxane with an epoxy equivalent of 900 to 1050 g / eq.

[0071] Preparation Example 3:

[0072] This preparation example provides a method for preparing epoxy-terminated polydimethylsiloxane, including the following steps:

[0073] Step 1: Add 100 parts by weight of hydrogen-terminated polydimethylsiloxane with a hydrogen mass fraction of 0.05% and 8 parts by weight of allyl glycidyl ether to the reactor. Seal the reactor and purge with nitrogen gas of 99.9% purity or higher. Each time the pressure is increased to 0.2 MPa, the gas is purged. Repeat the purging process 3 times, which takes 25 minutes. Then start stirring at 300 r / min and stir continuously for 20 minutes to mix the materials evenly. Then heat the mixture to 90°C to obtain the silicon-hydrogen reaction mixture premix.

[0074] Step 2: Add 0.8 parts by weight of a platinum isopropanol chloroplatinate solution with a mass concentration of 2000 ppm to the silane-hydrogen reaction mixture obtained in Step 1, keep the stirring speed at 300 r / min, control the reaction temperature at 95℃, and continue the reaction for 5 hours to obtain crude epoxy silicone oil.

[0075] Step 3: The crude epoxy silicone oil obtained in Step 2 is fed into a vacuum devolatilization device and subjected to vacuum devolatilization under an absolute pressure of 0.008 MPa and a temperature of 120°C for 3 hours to remove unreacted low molecular weight compounds, thereby obtaining epoxy-terminated polydimethylsiloxane with an epoxy equivalent of 1900 to 2200 g / eq.

[0076] Preparation Example 4:

[0077] This preparation example provides a method for preparing an anti-hydrolysis agent masterbatch, including the following steps:

[0078] Step 1: Add 100 parts by weight of diphenylmethane-4,4'-diisocyanate and 200 parts by weight of toluene to a reactor equipped with a reflux condenser, nitrogen protection device and tail gas outlet pipe. Turn on the stirring at 300 r / min and heat to the state of toluene reflux. Add 0.5 parts by weight of 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide. React for 4 hours under toluene reflux. The carbon dioxide generated during the reaction is discharged through the tail gas outlet pipe to obtain a polymer anti-hydrolysis mixture.

[0079] Step 2: The polymer anti-hydrolysis mixture obtained in Step 1 is fed into a devolatilization single-screw extruder and extruded and the toluene solvent is removed under the conditions of barrel temperature of 160℃ and absolute pressure of 0.01MPa. After air cooling and pelletizing, solid polymer anti-hydrolysis resin is obtained.

[0080] Step 3: 40 parts by weight of the solid polymer anti-hydrolysis resin obtained in Step 2 and 60 parts by weight of thermoplastic polyurethane elastomer granules are fed into a high-speed mixer and mixed at a speed of 500 r / min for 10 minutes to obtain a blended dry material. The blended dry material is then fed into a twin-screw extruder and melt-granulated under the conditions of barrel temperature of 180℃ and screw speed of 250 r / min. After air cooling and pelletizing, the material is sealed and stored to obtain an anti-hydrolysis agent masterbatch with an effective component mass fraction of 40%.

[0081] Preparation Example 5:

[0082] This preparation example provides a method for preparing an anti-hydrolysis agent masterbatch, including the following steps:

[0083] Step 1: Add 100 parts by weight of diphenylmethane-4,4'-diisocyanate and 200 parts by weight of toluene to a reactor equipped with a reflux condenser, nitrogen protection device and tail gas outlet pipe. Start stirring at 350 r / min and heat to the state of toluene reflux. Add 0.8 parts by weight of 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide and react for 5 hours under toluene reflux. The carbon dioxide generated during the reaction is discharged through the tail gas outlet pipe to obtain a polymer anti-hydrolysis mixture.

[0084] Step 2: The polymer anti-hydrolysis mixture obtained in Step 1 is fed into a devolatilization single-screw extruder and extruded and detox solvent is removed under the conditions of barrel temperature of 170℃ and absolute pressure of 0.01MPa. After air cooling and pelletizing, solid polymer anti-hydrolysis resin is obtained.

[0085] Step 3: 50 parts by weight of the solid polymer anti-hydrolysis resin obtained in Step 2 and 50 parts by weight of thermoplastic polyurethane elastomer granules are fed into a high-speed mixer and mixed at a speed of 600 r / min for 15 minutes to obtain a blended dry material. The blended dry material is then fed into a twin-screw extruder and melt-granulated under the conditions of barrel temperature of 185℃ and screw speed of 300 r / min. After air cooling and pelletizing, the material is sealed and stored to obtain an anti-hydrolysis agent masterbatch with an effective ingredient mass fraction of 50%.

[0086] Preparation Example 6:

[0087] This preparation example provides a method for preparing an anti-hydrolysis agent masterbatch, including the following steps:

[0088] Step 1: Add 100 parts by weight of diphenylmethane-4,4'-diisocyanate and 200 parts by weight of toluene to a reactor equipped with a reflux condenser, nitrogen protection device and tail gas outlet pipe. Start stirring at 400 r / min and heat to toluene reflux state. Add 1.0 part by weight of 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide. React for 6 hours under toluene reflux state. The carbon dioxide generated during the reaction is discharged through the tail gas outlet pipe to obtain a polymer anti-hydrolysis mixture.

[0089] Step 2: The polymer anti-hydrolysis mixture obtained in Step 1 is fed into a devolatilization single-screw extruder and extruded and the toluene solvent is removed under the conditions of barrel temperature of 180℃ and absolute pressure of 0.01MPa. After air cooling and pelletizing, solid polymer anti-hydrolysis resin is obtained.

[0090] Step 3: 60 parts by weight of the solid polymer anti-hydrolysis resin obtained in Step 2 and 40 parts by weight of thermoplastic polyurethane elastomer granules are fed into a high-speed mixer and mixed at 700 r / min for 20 minutes to obtain a blended dry material. The blended dry material is then fed into a twin-screw extruder and melt-granulated at a barrel temperature of 190℃ and a screw speed of 350 r / min. After air cooling and pelletizing, the material is sealed and stored to obtain an anti-hydrolysis agent masterbatch with an effective component mass fraction of 60%.

[0091] Example 1:

[0092] This embodiment provides a method for preparing a composite cable for photoelectric signal transmission, including the following steps:

[0093] S1: Insulated copper wires and quartz optical fibers are fed into a cabling machine for concentric stranding, with the stranding pitch controlled at 40mm, to obtain stranded core wires; polytetrafluoroethylene tape is continuously wrapped around the outside of the stranded core wires, with the wrapping overlap rate controlled at 25%, forming a basic isolation layer with a thickness of 0.08mm, to obtain the optoelectronic composite cable core.

[0094] S2: 100 parts by weight of thermoplastic polyurethane elastomer, 4 parts by weight of epoxidized soybean oil and 3 parts by weight of epoxy-terminated polydimethylsiloxane obtained in Preparation Example 2 are fed into a high-speed mixer and mixed evenly to obtain a buffer layer premixed dry material; the buffer layer premixed dry material is fed into a single screw extruder with an aspect ratio of 29 and extruded into a tube at a barrel temperature of 170°C, which is then wrapped around the outside of the optoelectronic composite cable core obtained in S1 to form a reactive slip buffer layer with a thickness of 0.15 mm, thus obtaining a cable core with a buffer layer.

[0095] S3: 50 parts by weight of thermoplastic polyurethane elastomer, 18 parts by weight of aluminum diethylphosphinate, and 12 parts by weight of melamine cyanurate are added to Zone 1 of a twin-screw extruder with a length-to-diameter ratio of 50 via the main feeder. The barrel temperature in Zone 1 is set to 145°C. The screw rotation mixes the materials and conveys them to Zone 2. When the materials in Zone 1 enter Zone 2, where the barrel temperature is 162°C, 4 parts by weight of epoxidized soybean oil are injected through the first injection port using a liquid pump. The injection pressure of the liquid pump is maintained at 3.5 MPa, and the materials form an initial melt mixture in Zone 2. In the downstream barrel section after the first injection port, the remaining 50 parts by weight of thermoplastic polyurethane elastomer are added to the initial melt mixture via the first side feeder. The newly added granules absorb heat and melt. The material forms a melt section in the barrel and is conveyed to the third zone. When the material from the second zone and the side feeding section enters the third zone at a barrel temperature of 168°C, 3 parts by weight of hydroxyl-terminated polydimethylsiloxane are injected through the second injection port by a liquid pump. The liquid and melt are further mixed and dispersed in the third zone. When the material in the third zone passes through the natural exhaust section and the vacuum exhaust section in sequence and enters the fourth zone at a barrel temperature of 162°C, 2.5 parts by weight of the anti-hydrolysis agent masterbatch obtained in Preparation Example 5 are added through the second side feeder. The mixture is dispersed and blended in the barrel of the fourth zone to obtain an outer sheath blend melt. The outer sheath blend melt is conveyed to the die head at a temperature of 152°C and extruded under the rotation of the screw at 400 r / min. The mixture is then pelletized, dehydrated, and dried to obtain a flame-retardant and anti-hydrolysis outer sheath material.

[0096] S4: The buffered cable core obtained in S2 is continuously fed into the center of the die head of a single screw extruder with a length-to-diameter ratio of 25. The die head adopts a tube extrusion die, and the stretch ratio is controlled at 2.2. The flame-retardant and hydrolysis-resistant outer sheath material obtained in S3 is fed into the single screw extruder, melted and plasticized under the conditions of barrel temperature of 148℃ and die head temperature of 155℃, and extruded to cover the outside of the buffered cable core. After covering, it immediately enters a cooling water tank at 18℃ for shaping and cooling. The optical signal transmission composite cable is obtained by the track traction mechanism.

[0097] Example 2:

[0098] This embodiment provides a method for preparing a composite cable for photoelectric signal transmission, including the following steps:

[0099] S1: Insulated copper wires and quartz optical fibers are fed into a cabling machine for concentric stranding, with the stranding pitch controlled at 30mm, to obtain stranded core wires; polytetrafluoroethylene tape is continuously wrapped around the outside of the stranded core wires, with the wrapping overlap rate controlled at 15%, forming a basic isolation layer with a thickness of 0.05mm, to obtain the optoelectronic composite cable core.

[0100] S2: 100 parts by weight of thermoplastic polyurethane elastomer, 3 parts by weight of epoxidized soybean oil and 2 parts by weight of epoxy-terminated polydimethylsiloxane obtained in Preparation Example 1 are fed into a high-speed mixer and mixed evenly to obtain a buffer layer premixed dry material; the buffer layer premixed dry material is fed into a single screw extruder with an aspect ratio of 28 and extruded into a tube at a barrel temperature of 160°C, which is then wrapped around the outside of the optoelectronic composite cable core obtained in S1 to form a reactive slip buffer layer with a thickness of 0.1 mm, thus obtaining a cable core with a buffer layer.

[0101] S3: 50 parts by weight of thermoplastic polyurethane elastomer, 15 parts by weight of aluminum diethylphosphinate, and 10 parts by weight of melamine cyanurate are added to Zone 1 of a twin-screw extruder with a length-to-diameter ratio of 48 via the main feeder. The barrel temperature of Zone 1 is set to 140°C. The screw rotation mixes the materials and conveys them to Zone 2. When the materials in Zone 1 enter Zone 2, where the barrel temperature is 160°C, 3 parts by weight of epoxidized soybean oil are injected through the first injection port via a liquid pump. The injection pressure of the liquid pump is maintained at 2 MPa, and the materials form an initial melt mixture in Zone 2. In the downstream barrel section after the first injection port, the remaining 50 parts by weight of thermoplastic polyurethane elastomer are added to the initial melt mixture via the first side feeder. The newly added granules absorb heat and melt. The material forms a melt section in the barrel and is conveyed to the third zone. When the material from the second zone and the side feeding section enters the third zone where the barrel temperature is 165°C, 2 parts by weight of hydroxyl-terminated polydimethylsiloxane are injected through the second injection port by a liquid pump. The liquid and melt are further mixed and dispersed in the third zone. When the material in the third zone passes through the natural exhaust section and the vacuum exhaust section in sequence and enters the fourth zone where the barrel temperature is 160°C, 2 parts by weight of the anti-hydrolysis agent masterbatch obtained in Preparation Example 4 are added through the second side feeder. The mixture is dispersed and blended in the barrel of the fourth zone to obtain an outer sheath blend melt. The outer sheath blend melt is conveyed to the die head where the temperature is 150°C and extruded under the rotation of the screw at 300 r / min. The mixture is then pelletized, dehydrated, and dried to obtain a flame-retardant and anti-hydrolysis outer sheath material.

[0102] S4: The buffered cable core obtained in S2 is continuously fed into the center of the die head of a single screw extruder with a length-to-diameter ratio of 25. The die head adopts a tube extrusion die, and the stretch ratio is controlled at 1.5. The flame-retardant and hydrolysis-resistant outer sheath material obtained in S3 is fed into the single screw extruder, melted and plasticized under the conditions of barrel temperature of 140℃ and die head temperature of 150℃, and extruded to cover the outside of the buffered cable core. After covering, it is immediately placed in a 15℃ cooling water tank for shaping and cooling. The optical signal transmission composite cable is obtained by the track traction mechanism.

[0103] Example 3:

[0104] This embodiment provides a method for preparing a composite cable for photoelectric signal transmission, including the following steps:

[0105] S1: Insulated copper wires and quartz optical fibers are fed into a cabling machine for concentric stranding, with the stranding pitch controlled at 50mm, to obtain stranded core wires; polytetrafluoroethylene tape is continuously wrapped around the outside of the stranded core wires, with the wrapping overlap rate controlled at 30%, forming a basic isolation layer with a thickness of 0.1mm, to obtain the optoelectronic composite cable core.

[0106] S2: 100 parts by weight of thermoplastic polyurethane elastomer, 5 parts by weight of epoxidized soybean oil and 4 parts by weight of epoxy-terminated polydimethylsiloxane obtained in Preparation Example 3 are fed into a high-speed mixer and mixed evenly to obtain a buffer layer premixed dry material; the buffer layer premixed dry material is fed into a single screw extruder with an aspect ratio of 30 and extruded into a tube at a barrel temperature of 180°C, which is then wrapped around the outside of the optoelectronic composite cable core obtained in S1 to form a reactive slip buffer layer with a thickness of 0.2 mm, thus obtaining a cable core with a buffer layer.

[0107] S3: 50 parts by weight of thermoplastic polyurethane elastomer, 20 parts by weight of aluminum diethylphosphinate, and 15 parts by weight of melamine cyanurate are added to Zone 1 of a twin-screw extruder with an aspect ratio of 52 via the main feeder. The barrel temperature in Zone 1 is set to 150°C. The screw rotation mixes the materials and conveys them to Zone 2. When the materials in Zone 1 enter Zone 2, where the barrel temperature is 165°C, 5 parts by weight of epoxidized soybean oil are injected through the first injection port using a liquid pump. The injection pressure of the liquid pump is maintained at 5 MPa, and the materials form an initial melt mixture in Zone 2. In the downstream barrel section after the first injection port, the remaining 50 parts by weight of thermoplastic polyurethane elastomer are added to the initial melt mixture via the first side feeder. The newly added granules absorb heat and melt. The material forms a melt section in the barrel and is conveyed to the third zone. When the material from the second zone and the side feeding section enters the third zone where the barrel temperature is 170°C, 4 parts by weight of hydroxyl-terminated polydimethylsiloxane are injected through the second injection port by a liquid pump. The liquid and melt are further mixed and dispersed in the third zone. When the material in the third zone passes through the natural exhaust section and the vacuum exhaust section in sequence and enters the fourth zone where the barrel temperature is 165°C, 3 parts by weight of the anti-hydrolysis agent masterbatch obtained in Preparation Example 6 are added through the second side feeder. The mixture is dispersed and blended in the barrel of the fourth zone to obtain an outer sheath blend melt. The outer sheath blend melt is conveyed to the die head where the temperature is 155°C and extruded under the rotation of the screw at 500 r / min. The mixture is then pelletized, dehydrated, and dried to obtain a flame-retardant and anti-hydrolysis outer sheath material.

[0108] S4: The buffered cable core obtained in S2 is continuously fed into the center of the die head of a single screw extruder with a length-to-diameter ratio of 25. The die head adopts a tube extrusion die, and the stretch ratio is controlled at 3.0. The flame-retardant and hydrolysis-resistant outer sheath material obtained in S3 is fed into the single screw extruder, melted and plasticized under the conditions of barrel temperature of 155℃ and die head temperature of 160℃, and extruded to cover the outside of the buffered cable core. After covering, it immediately enters a 20℃ cooling water tank for shaping and cooling. The optical signal transmission composite cable is obtained by the track traction mechanism.

[0109] Example 4:

[0110] This embodiment provides a method for preparing a composite cable for photoelectric signal transmission, including the following steps:

[0111] S1: Insulated copper wires and quartz optical fibers are fed into a cabling machine for concentric stranding, with the stranding pitch controlled at 45mm, to obtain stranded core wires; polytetrafluoroethylene tape is continuously wrapped around the outside of the stranded core wires, with the wrapping overlap rate controlled at 20%, forming a basic isolation layer with a thickness of 0.06mm, to obtain the optoelectronic composite cable core.

[0112] S2: 100 parts by weight of thermoplastic polyurethane elastomer, 3.5 parts by weight of epoxidized soybean oil and 3.5 parts by weight of epoxy-terminated polydimethylsiloxane obtained in Preparation Example 2 are fed into a high-speed mixer and mixed evenly to obtain a buffer layer premixed dry material; the buffer layer premixed dry material is fed into a single screw extruder with an aspect ratio of 29 and extruded into a tube at a barrel temperature of 175°C, which is then wrapped around the outside of the optoelectronic composite cable core obtained in S1 to form a reactive slip buffer layer with a thickness of 0.12 mm, thus obtaining a cable core with a buffer layer.

[0113] S3: 40 parts by weight of thermoplastic polyurethane elastomer, 16 parts by weight of aluminum diethylphosphinate, and 11 parts by weight of melamine cyanurate are added to Zone 1 of a twin-screw extruder with an aspect ratio of 50 via the main feeder. The barrel temperature in Zone 1 is set to 148°C. The screw rotation mixes the materials and conveys them to Zone 2. When the materials in Zone 1 enter Zone 2, where the barrel temperature is 164°C, 3.5 parts by weight of epoxidized soybean oil are injected through the first injection port using a liquid pump. The injection pressure of the liquid pump is maintained at 4 MPa, and the materials form an initial melt mixture in Zone 2. In the downstream barrel section after the first injection port, the remaining 60 parts by weight of thermoplastic polyurethane elastomer are added to the initial melt mixture via the first side feeder. The newly added granules absorb heat and melt. A melt section is formed inside the barrel and conveyed to Zone 3. When the material from Zone 2 and the side feeding section enters Zone 3, where the barrel temperature is 166°C, 3.5 parts by weight of hydroxyl-terminated polydimethylsiloxane is injected through the second injection port using a liquid pump. The liquid and melt are further mixed and dispersed in Zone 3. When the material in Zone 3 passes through the natural exhaust section and the vacuum exhaust section in sequence and enters Zone 4, where the barrel temperature is 164°C, 2.8 parts by weight of the anti-hydrolysis agent masterbatch obtained in Preparation Example 5 is added through the second side feeder. The mixture is dispersed and blended in the barrel of Zone 4 to obtain an outer sheath blend melt. The outer sheath blend melt is conveyed to the die head at a temperature of 154°C and extruded under a screw rotation of 450 r / min. The mixture is then pelletized, dehydrated, and dried to obtain a flame-retardant and anti-hydrolysis outer sheath material.

[0114] S4: The buffered cable core obtained in S2 is continuously fed into the center of the die head of a single screw extruder with a length-to-diameter ratio of 25. The die head adopts a tube extrusion die, and the stretch ratio is controlled at 2.8. The flame-retardant and hydrolysis-resistant outer sheath material obtained in S3 is fed into the single screw extruder, melted and plasticized under the conditions of barrel temperature of 150℃ and die head temperature of 158℃, and extruded to cover the outside of the buffered cable core. After covering, it immediately enters a 16℃ cooling water tank for shaping and cooling. The optical signal transmission composite cable is obtained by the track traction mechanism.

[0115] In Examples 1 to 4, the twin-screw extruder is sequentially configured with Zone 1, Zone 2, Zone 3, natural exhaust section, vacuum exhaust section, Zone 4, and die head along the material conveying direction; the first injection port is located in Zone 2, downstream of the first melt kneading section and within the melt pressure establishment area of ​​Zone 2; the feeding position of the first side feeder is located in the downstream barrel section after the first injection port, and between the first injection port and the second injection port; the second injection port is located in Zone 3, at the inlet end or middle of the second mixing and kneading section of Zone 3; the feeding position of the second side feeder is located after the vacuum exhaust section and before the metering and conveying section of Zone 4.

[0116] Comparative Example 1:

[0117] Compared with Example 1, the difference lies in the following: the feeding sequence and method in step S3 are changed. In step S3, the staged feeding of second-zone liquid injection, downstream side feeding of the first injection port, third-zone liquid injection, and front-end side feeding of the fourth zone is not performed. Instead, 100 parts by weight of thermoplastic polyurethane elastomer, 18 parts by weight of aluminum diethylphosphinate, 12 parts by weight of melamine cyanurate, 4 parts by weight of epoxidized soybean oil, 3 parts by weight of hydroxyl-terminated polydimethylsiloxane, and 2.5 parts by weight of the anti-hydrolysis agent masterbatch obtained in Preparation Example 5 are all fed through the main feeder in one go. The mixture is added to Zone 1 of a twin-screw extruder. Subsequently, the mixture is conveyed sequentially through Zone 2 (162°C), Zone 3 (168°C), the natural exhaust section, the vacuum exhaust section, and Zone 4 (162°C) under the rotation of the screw. During this process, no further granule addition or liquid injection is performed in any section of the barrel. The blended melt is finally conveyed to the die head at 152°C according to the original parameters, extruded at a screw speed of 400 r / min, and pelletized and dried. Except for the above differences, the operation and process parameters of the other steps are the same as in Example 1.

[0118] Comparative Example 2:

[0119] Compared with Example 1, the difference lies in the following: the feeding position and liquid injection method in step S3 are changed. In step S3, 100 parts by weight of thermoplastic polyurethane elastomer are added to Zone 1 through the main feeder (i.e., no more thermoplastic polyurethane elastomer is added to the downstream barrel section after the first injection port); and in Zone 2, 4 parts by weight of epoxidized soybean oil and 3 parts by weight of hydroxyl-terminated polydimethylsiloxane are simultaneously injected into the barrel from the first injection port through a liquid pump (i.e., no more liquid is injected into Zone 3). Subsequently, the material is conveyed through Zone 3, where the barrel temperature is 168°C, for mixing and dispersion. Then, it passes through the natural exhaust section and the vacuum exhaust section in sequence and enters Zone 4, where the barrel temperature is 162°C. At the same time, 2.5 parts by weight of the anti-hydrolysis agent masterbatch obtained in Preparation Example 5 are added through the second side feeder for dispersion and blending. Finally, it is conveyed to the die head at a temperature of 152°C according to the original parameters, and extruded at a screw speed of 400 r / min, and then pelletized and dried. Except for the above differences, the operation and process parameters of the other steps are the same as those in Example 1.

[0120] Comparative Example 3:

[0121] Compared with Example 1, the difference is that step S2 is omitted, i.e., the reactive slip buffer layer containing epoxidized soybean oil and epoxidized end-capped polydimethylsiloxane is not formed on the outside of the polytetrafluoroethylene tape. In step S4, the object of the extruded and coated cable core matrix is ​​changed. Specifically, the optoelectronic composite cable core obtained in S1 (replacing the cable core with the buffer layer) is continuously fed into the center of the die head of a single screw extruder with an aspect ratio of 25. The die head still uses a tube extrusion die, and the draw ratio is controlled at 2.2. The flame-retardant and hydrolysis-resistant outer sheath material obtained in S3 is fed into the single screw extruder, melted and plasticized under the condition of maintaining the barrel temperature at 148°C and the die head temperature at 155°C, and extruded directly coated onto the outer base isolation layer of the optoelectronic composite cable core obtained in S1. After coating, it immediately enters a cooling water tank at 18°C ​​for shaping and cooling, and is pulled into a cable by a crawler. Except for the above differences, the operation and process parameters of the other steps are the same as those in Example 1.

[0122] Comparative Example 4:

[0123] Compared with Example 1, the difference lies in the following: the raw material composition in step S2 is changed. In step S2, 4 parts by weight of epoxidized soybean oil and 3 parts by weight of the epoxy-terminated polydimethylsiloxane obtained in Preparation Example 2 are not added. Instead, 100 parts by weight of thermoplastic polyurethane elastomer are fed into a single-screw extruder with an aspect ratio of 29 and extruded into a tube while maintaining the barrel temperature at 170°C. This tube is then wrapped around the outside of the optoelectronic composite cable core obtained in S1 to form a pure thermoplastic polyurethane buffer layer with a thickness of 0.15 mm, resulting in a cable core with a buffer layer. Subsequently, the cable core with the buffer layer is fed into step S4 according to the original process parameters for the extrusion of flame-retardant and hydrolysis-resistant outer sheath material. Except for the above differences, the operation and process parameters of the other steps are the same as those in Example 1.

[0124] Test Example 1:

[0125] Experimental steps:

[0126] Flame-retardant and hydrolysis-resistant outer sheath materials prepared in step S3 of Examples 1 to 4 and Comparative Example 1 were selected as test objects. 2.5000 g to 2.5100 g of granulated material were weighed as test samples for the corresponding groups. Each test sample was chopped to a particle size not exceeding 1 mm and placed in a stoppered Erlenmeyer flask equipped with a reflux condenser. 50 mL of a 1:1 mixture of anhydrous toluene and tetrahydrofuran was added to each flask. The flask was heated in a constant temperature water bath at 65°C with continuous magnetic stirring for 2.5 hours to extract the soluble hydrolysis-resistant active components from the test samples, yielding an extract. After extraction, each extract was cooled to 25°C and filtered. The resulting filtrate was used as the titration sample solution for the corresponding group.

[0127] To each of the above sample solutions, accurately add 25.00 mL of a 0.1005 mol / L di-n-butylamine-toluene standard solution, seal the flask, and place it on a shaker at 120 r / min for 45 minutes to allow the di-n-butylamine to fully contact and react with the free carbodiimide groups in the solution.

[0128] Add 50 mL of anhydrous isopropanol as a diluent to the reacted solution, add 4 to 5 drops of bromocresol green-methyl red mixed indicator, and titrate with a 0.1012 mol / L hydrochloric acid standard solution until the solution changes from blue-green to a slightly red color and remains unchanged for 30 seconds. Record the volume of hydrochloric acid standard solution consumed. A blank experiment is also performed without the test sample. Without adding the test granules, add an equal volume of anhydrous toluene and tetrahydrofuran mixed solvent to the flask, and perform heating, stirring, cooling, filtration, addition of di-n-butylamine-toluene standard solution, shaking reaction, isopropanol dilution, and titration with hydrochloric acid standard solution under the same conditions. Record the volume of hydrochloric acid standard solution consumed in the blank experiment.

[0129] After the titration test, the obtained experimental data were calculated and analyzed. First, based on the weight fraction of the anti-hydrolysis agent masterbatch actually added in each embodiment and comparative formulation and its corresponding effective component mass fraction, the amount of carbodiimide groups that should theoretically be present in a unit mass of sheath granulated material was calculated and converted into the content per 100g of sheath granulated material, recorded as the theoretical effective carbodiimide group content. Subsequently, based on the difference in the volume of hydrochloric acid standard solution consumed by the blank experiment and the actual test sample during the above titration process, combined with the hydrochloric acid concentration and sample mass, the amount of detectable non-deactivated carbodiimide groups in each 100g of sheath granulated material was calculated and recorded as the actual measured carbodiimide group content. Finally, the calculated actual measured carbodiimide group content was divided by the theoretical effective carbodiimide group content and multiplied by 100% to obtain the process retention rate of the active groups of the corresponding test sample.

[0130] The test results are shown in Table 1:

[0131] Table 1: Results of the determination of carbodiimide group retention rate in flame-retardant and hydrolysis-resistant outer sheath materials

[0132] Test object Theoretical effective carbodiimide group content (mmol / 100g) Actual determination of carbodiimide group content (mmol / 100g) Retention rate of active groups during the process (%) Example 1 8.13 7.55 92.86 Example 2 5.21 4.72 90.59 Example 3 11.68 10.88 93.15 Example 4 9.15 8.35 91.25 Comparative Example 1 8.13 2.29 28.16

[0133] Test conclusion:

[0134] According to Table 1 and Figure 1 As shown, in the flame-retardant and hydrolysis-resistant outer sheath materials prepared in Examples 1 to 4, the process retention rate of active groups was maintained between 90.59% and 93.15%, while the process retention rate of active groups in Comparative Example 1 was 28.16%. Compared with Comparative Example 1, the detectable carbodiimide active groups in the outer sheath materials obtained in Examples 1 to 4 were at a higher level.

[0135] Comparative Example 1 uses a one-time blending and feeding process. The polycarbodiimide anti-hydrolysis component in the anti-hydrolysis agent masterbatch enters the highly filled melt environment containing aluminum diethylphosphinate earlier. Under high-temperature shear conditions, acidic impurities that may exist on the surface of the flame retardant powder will increase the risk of carbodiimide groups being consumed or deactivated, resulting in a relatively low actual measured content of carbodiimide groups.

[0136] In Examples 1 to 4, a segmented feeding method was adopted in the twin-screw extrusion process. Epoxidized soybean oil was injected before the anti-hydrolysis agent masterbatch was added, so that the epoxy groups in the epoxidized soybean oil could first contact with the acidic sites that might exist on the surface of aluminum diethylphosphinate and undergo a ring-opening reaction. This feeding sequence helps to reduce the adverse effects of the acidic sites on the surface of the flame retardant powder on the polycarbodiimide anti-hydrolysis component added in the subsequent side feed, so that the carbodiimide groups in the resulting sheath material maintain a high detectable retention level.

[0137] Test Example 2:

[0138] Experimental steps:

[0139] The twin-screw extrusion processing parameters during the preparation of the flame-retardant and hydrolysis-resistant outer sheath material in step S3 of Examples 1 to 4 and Comparative Example 2 were used as test objects. After the temperature of each temperature zone of the twin-screw extruder reached the set process parameters and continuous feeding began, the discharge status of the die head was observed. Once the die head discharge was continuous and the equipment operation was stable, timing was started and continuous data acquisition was performed for 2 hours. Using the control system and data acquisition module of the twin-screw extruder, the main current of the equipment and the melt pressure of the die head were continuously recorded with a sampling period of 1 minute. A total of 120 data points were acquired during the entire test cycle.

[0140] After data acquisition, the recorded parameters are calculated and analyzed. The arithmetic mean of the 120 main unit current data points collected within 2 hours is recorded as the main unit current average. The maximum and minimum main unit current values ​​within the test period are extracted, the difference between the two is calculated and divided by the main unit current average, and then multiplied by 100% to obtain the main unit current fluctuation rate. The arithmetic mean of the 120 head melt pressure data points is recorded as the head melt pressure average. The maximum and minimum head melt pressure values ​​within the test period are extracted, and the difference between the two is calculated to obtain the head melt pressure range.

[0141] The test results are shown in Table 2:

[0142] Table 2: Extrusion Rheology and Processing Stability Test Data of Flame-Retardant and Hydrolysis-Resistant Outer Sheath Material

[0143] Test object Average host current (A) Host current fluctuation rate (%) Average melt pressure at the die head (MPa) Die head melt pressure differential range (MPa) Example 1 65.4 2.82 12.6 0.42 Example 2 61.2 2.56 11.4 0.37 Example 3 68.7 3.15 13.5 0.51 Example 4 63.8 2.97 12.1 0.45 Comparative Example 2 52.3 18.42 9.8 4.68

[0144] Test conclusion:

[0145] According to Table 2 and Figure 2 As shown, in the twin-screw continuous extrusion test of Examples 1 to 4, the main machine current fluctuation rate was 2.56% to 3.15%, and the die head melt pressure range was 0.37 MPa to 0.51 MPa. Compared with Examples 1 to 4, the main machine current fluctuation rate of Comparative Example 2 increased to 18.42%, the die head melt pressure range increased to 4.68 MPa, and the average main machine current and the average die head melt pressure were relatively low.

[0146] In Comparative Example 2, epoxidized soybean oil and hydroxyl-terminated polydimethylsiloxane were injected into the same processing section. This section lacked a dry material transition section for absorbing the liquid phase materials, potentially leading to localized enrichment of the two liquid phase materials on the screw surface or at the melt interface. Under these conditions, the frictional traction between the screw and the material may weaken, and fluctuations may occur in material conveying and die head pressure build-up, resulting in increased main engine current fluctuations and a wider range of melt pressure differences at the die head.

[0147] In Examples 1 to 4, between the two liquid phase material injection sections, dry thermoplastic polyurethane elastomer material is added via a first-side feeder. This dry material absorbs and disperses the residual liquid phase material from the preceding section during the melting process, forming a transitional melt section within the barrel, reducing direct aggregation and backmixing of the liquid phase materials. The stepwise addition of liquid substances, which separately contact and mix with the polyurethane matrix and powder, helps improve the continuity of the high-filled blend melt conveying in the screw and the stability of the die head pressure build-up, reducing the tendency for material slippage and pressure fluctuations.

[0148] Test Example 3:

[0149] Experimental steps:

[0150] The photoelectric signal transmission composite cables prepared in Examples 1 to 4 and Comparative Example 1 were selected as test samples. Each group of photoelectric signal transmission composite cables was cut into several segments of 150 mm in length. The internal stranded core wires, PTFE tape, and reactive slip buffer layer were removed, leaving only the outermost tubular sample composed of a flame-retardant and hydrolysis-resistant outer sheath material, i.e., the outer sheath segment. Each group of outer sheath segments was divided into a pre-aging control sample and a post-aging test sample to compare the changes in tensile properties before and after steam circulation treatment.

[0151] The outer sheath sections of the pre-aging control samples in each group were placed in a constant temperature and humidity environment of 23℃ and 50% for 24 hours for conditioning. Tensile tests were then performed on the conditioned pre-aging control samples using an electronic universal testing machine at a tensile speed of 200 mm / min. The maximum tensile stress value and gauge length elongation at sample fracture were recorded, and these were used as the initial tensile strength and initial elongation at break, respectively.

[0152] The outer sheath of each group of aged test samples was placed in a medical high-pressure steam sterilizer for hydrothermal aging treatment. The temperature inside the sterilizer was set to 134℃, the steam gauge pressure to 0.2MPa, and a single steam treatment cycle to 18 minutes. After each cycle, the samples were removed and allowed to cool naturally to room temperature. This cycle was repeated until each group of test samples had completed a total of 1000 high-pressure steam cycles.

[0153] After 1000 steam cycles, the surface of the outer sheath of each group of test samples was wiped clean, and then placed in the same constant temperature and humidity environment as before for 24 hours for conditioning. Tests were conducted using the same electronic universal testing machine and tensile parameters. The maximum tensile stress at tensile fracture and the percentage elongation of the gauge length were recorded, and these were used as the tensile strength and elongation at break after treatment, respectively.

[0154] After all tensile mechanical tests were completed, the acquired data were calculated and analyzed. Test data for each group of samples were extracted, and the tensile strength after treatment was divided by the corresponding initial tensile strength and multiplied by 100% to calculate the tensile strength retention rate of the sample. Similarly, the elongation at break after treatment was divided by the corresponding initial elongation at break and multiplied by 100% to calculate the elongation at break retention rate of the sample. The mechanical retention rate obtained from the above calculations reflects the degree of molecular chain degradation of the corresponding thermoplastic polyurethane elastomer sheath material under long-term high-temperature and high-pressure hydrothermal action.

[0155] The test results are shown in Table 3:

[0156] Table 3: Durability Test Data of High Temperature and High Pressure Steam Sterilization for Sheathed Pipe Sections

[0157] Test object Tensile strength retention rate (%) Elongation at break retention rate (%) Example 1 85.19 85.18 Example 2 81.49 80.45 Example 3 88.96 87.89 Example 4 83.07 83.44 Comparative Example 1 34.89 10.04

[0158] Test conclusion:

[0159] According to the data in Table 3, after undergoing 1000 cycles of high-temperature and high-pressure steam treatment, the tensile strength retention rate of the outer sheath tube segments in Examples 1 to 4 was between 81.49% and 88.96%, and the elongation at break retention rate was between 80.45% and 87.89%. In contrast, after being treated under the same conditions, the tensile strength retention rate of the outer sheath tube segment in Comparative Example 1 decreased to 34.89%, and the elongation at break retention rate decreased to 10.04%, with the material exhibiting more obvious macroscopic embrittlement characteristics.

[0160] In Comparative Example 1, no segmented feeding was performed during the granulation process. The polycarbodiimide anti-hydrolysis component in the anti-hydrolysis agent masterbatch was easily affected by the acidic components on the surface of the flame retardant powder and was partially consumed in advance. This meant that in the test environment where the cable faced high temperature and moisture intrusion at 134°C, the outer sheath lacked a sufficient number of active carbodiimide groups. The terminal carboxyl groups generated by the hydrolysis of the polyurethane matrix were prone to triggering an autocatalytic effect, which accelerated the degradation and breakage of the polymer main chain, ultimately resulting in a significant decrease in macroscopic mechanical properties.

[0161] In comparison, Examples 1 to 4 utilize epoxy groups to preferentially consume or neutralize acidic sites on the powder surface during processing, allowing the polycarbodiimide anti-hydrolysis component to retain better reactivity. When subsequently subjected to high-temperature, high-pressure water vapor intrusion, the effective carbodiimide groups remaining inside the outer sheath can undergo addition reactions with the free end carboxyl groups generated by polyurethane hydrolysis to generate acylurea structures and reduce the content of free acidic groups in the system. This process helps to inhibit the hydrolysis autocatalysis initiated by acidic groups and delay the continuous breakage of the molecular backbone, thereby helping to maintain the basic mechanical properties of the material after multiple high-temperature hydrothermal shocks.

[0162] Test Example 4:

[0163] Experimental steps:

[0164] The photoelectric signal transmission composite cables prepared in Examples 1 to 4, Comparative Examples 3 and 4 were selected as test objects. 1000-meter-long finished cable samples were cut from each of the above groups and wound with constant tension onto a wooden test spool of optical cable of the same standard diameter. The cable samples wound on the test spool were then placed in an indoor environment at 20°C for 24 hours to eliminate the additional mechanical tension generated during the winding process. The transmission attenuation of the quartz optical fiber inside each group of cable samples was tested using an optical time domain reflectometer set to a test wavelength of 1300 nm, and the first-stage attenuation reading of the instrument was recorded.

[0165] After completing the above tests, the same batch of tested cable samples, along with the test trays, were moved into a high and low temperature alternating test chamber for thermal cycling. The set single temperature cycle program was as follows: the test chamber temperature was lowered from 20℃ to -40℃ within 1 hour and held at that temperature for 2 hours; then the temperature was raised to 85℃ within 2 hours and held at that temperature for 2 hours; finally, the temperature was lowered to 20℃ within 1 hour. This temperature cycle program was repeated and 50 cycles were completed. After that, each group of cable samples was taken out and allowed to recover in a 20℃ environment for 24 hours. The transmission attenuation of the quartz optical fiber in this batch of cable samples was tested again using an optical time domain reflectometer at a wavelength of 1300nm, and the second-stage attenuation reading of the instrument was recorded.

[0166] After the test cycle is completed, the acquired attenuation data is processed by subtracting the baseline attenuation value of the batch of bare quartz optical fiber before cabling from the measured first-stage attenuation reading to calculate the initial additional attenuation of the corresponding cable sample. Similarly, the same baseline attenuation value is subtracted from the measured second-stage attenuation reading to calculate the additional attenuation after thermal cycling of the corresponding cable sample. The initial additional attenuation and the additional attenuation after thermal cycling of the same cable sample are used to evaluate the changes in optical fiber transmission stability after cabling and temperature cycling.

[0167] The test results are shown in Table 4:

[0168] Table 4: Fiber Additional Attenuation and Thermal Cycling Test Data

[0169] Test object Initial additional attenuation (dB / km) Additional degradation after thermal cycling (dB / km) Example 1 0.16 0.19 Example 2 0.13 0.17 Example 3 0.18 0.22 Example 4 0.15 0.18 Comparative Example 3 0.72 1.58 Comparative Example 4 0.23 0.94

[0170] Test conclusion:

[0171] According to the data in Table 4, the initial additional attenuation of the photoelectric signal transmission composite cables in Examples 1 to 4 ranged from 0.13 dB / km to 0.18 dB / km. After 50 high and low temperature thermal cycles, the additional attenuation remained between 0.17 dB / km and 0.22 dB / km. The overall attenuation index was at a low level and was less affected by temperature changes. In contrast, the initial additional attenuation of Comparative Example 3 reached 0.72 dB / km and rose to 1.58 dB / km after thermal cycling, while the initial additional attenuation of Comparative Example 4 was 0.23 dB / km, but it rose significantly to 0.94 dB / km after thermal cycling.

[0172] In Comparative Example 3, the composite cable structure lacks a buffer layer. During the extrusion and cooling shrinkage of the outer sheath, the highly packed network containing rigid flame-retardant particles directly compresses the quartz optical fiber, easily causing micro-bending deformation and resulting in a larger initial additional attenuation. This attenuation further deteriorates during the stress release process of thermal cycling. Comparative Example 4 uses pure thermoplastic polyurethane as a buffer layer, which can buffer some of the extrusion stress in the early stages of cabling. However, the pure polyurethane layer and the outer sheath are only physically bonded without forming a chemical bond network. During high and low temperature alternation, the difference in the coefficients of linear expansion between the two materials easily leads to interface debonding or localized stress concentration. This makes it difficult for the shrinkage stress of the outer sheath to be effectively dissipated through the interface and concentrated and transferred to the internal optical fiber, resulting in a significant increase in additional attenuation after thermal cycling.

[0173] Examples 1 to 4 involve extruding a reactive slip buffer layer onto the outer surface of the optical fiber. During the high-temperature molten state of the extrusion process, this buffer layer material not only forms a compatible fusion interface with the outer sheath matrix, but its epoxy groups can also react with residual acidic sites or hydroxyl-containing components at the interface, thereby forming a reactive bonding interface. Simultaneously, the flexible siloxane segments within the buffer layer provide a certain molecular-level slip space for the interface. When the outer sheath experiences volume shrinkage or expansion stress due to alternating ambient temperatures, this stress is more easily homogenized and dissipated through the slip-resistant buffer interface, helping to reduce stress concentration in the central optical fiber. This, in turn, helps maintain low attenuation and stable transmission of the optical fiber under complex temperature operating conditions.

[0174] Test Example 5:

[0175] Experimental steps:

[0176] The finished photoelectric signal transmission composite cables prepared in Examples 1 to 4 were selected as test objects. The newly made composite cables of each group were cut into segments of 600 mm in length, and five independent samples were prepared in parallel for each group. Then, each group of samples was placed in an environment with a temperature of 23°C and a relative humidity of 50% for 48 hours to allow them to stand and adjust. Using a test chamber that meets the general standard for vertical combustion, the adjusted samples were vertically clamped and fixed on the support inside the test chamber according to the cable vertical combustion test method. At the same time, a layer of medical absorbent cotton was laid flat on the bottom of the test chamber directly below the sample.

[0177] Turn on the test torch and adjust the gas flow to bring the test flame to the specified calorific value. Tilt the torch at a 20-degree angle and apply the flame to the lower part of the sample. Continue applying the flame for 15 seconds, then remove the torch. After the flame on the sample surface extinguishes naturally and 15 seconds have elapsed since the torch was removed, apply the flame again at the same angle for 15 seconds. Repeat this flame application and removal process until a total of 5 flame applications have been performed on a single sample.

[0178] Throughout the combustion test, a timer was used to record the time each sample maintained flame on its surface after the torch flame was removed. After five firing cycles for a single sample, the maximum recorded time was taken as the maximum afterburning time for that sample. The highest maximum afterburning time among the five samples in each group was also recorded as the maximum afterburning time. Simultaneously, throughout the multiple firing cycles and spontaneous combustion, it was continuously observed whether any burning polymer droplets fell. If any droplets from any sample ignited the absorbent cotton at the bottom, causing it to burn continuously, this was recorded as igniting the absorbent cotton; otherwise, it was recorded as not igniting.

[0179] The test results are shown in Table 5:

[0180] Table 5: Key Data from Vertical Combustion Test of Finished Cables

[0181] Test object Maximum afterburner time (s) Did the bottom absorbent cotton ignite? Example 1 6.4 no Example 2 4.7 no Example 3 7.2 no Example 4 5.8 no

[0182] Test conclusion:

[0183] According to the data in Table 5, after five flame operations, the finished optoelectronic composite cables of Examples 1 to 4 had a maximum afterburn time between 4.7s and 7.2s. Furthermore, during the flame exposure and self-extinguishing processes, none of the samples produced burning droplets that ignited the bottom degreased cotton, demonstrating stable halogen-free flame retardant performance.

[0184] Examples 1 to 4 introduced liquid epoxidized soybean oil and a siloxane-containing buffer layer during the processing. In conventional blending systems, liquid phases or low-molecular-weight substances are prone to migration outwards when heated at high temperatures and can act as combustibles, initiating continuous combustion. However, in this scheme, during the extrusion processing stage, the epoxy groups inside the epoxidized soybean oil readily undergo ring-opening reactions with the acidic substances on the surface of aluminum diethylphosphines, which helps to change the free state of the liquid phase components.

[0185] Meanwhile, the siloxane segments in the buffer layer form a compatible interface with the polyurethane matrix and the siloxane additives in the outer sheath, and the epoxy groups can participate in the reaction of residual acidic sites or hydroxyl-containing components at the interface, thereby further reducing the tendency of low molecular weight liquid phase components to migrate freely. This structure helps to limit the thermal migration of low melting point components in the formulation system to the outer surface of the cable.

[0186] Based on this, the microscopic dispersion network of the main flame retardant, aluminum diethylphosphonate, in the matrix facilitates its retention. When the cable exterior comes into contact with a flame, the flame retardant decomposes thermally to generate phosphorus-containing free radicals, which consume hydrogen free radicals in the gaseous flame zone, while simultaneously catalyzing char formation on the solid surface. Through the above modification process, the cable improves its processing rheological properties and hydrolytic stability while maintaining the intrinsic flame retardant efficacy of the high-filler flame retardant system.

[0187] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite cable for transmitting photoelectric signals, characterized in that, It includes, from the inside out, a fiber optic composite cable core, a reactive slip buffer layer, and a flame-retardant and hydrolysis-resistant outer sheath; The reactive slip buffer layer is made from the following raw materials in parts by weight: 100 parts by weight of thermoplastic polyurethane elastomer; 3 to 5 parts by weight of epoxidized soybean oil; and 2 to 4 parts by weight of epoxy-terminated polydimethylsiloxane. The flame-retardant and hydrolysis-resistant outer sheath is made from the following raw materials in parts by weight: 100 parts by weight of thermoplastic polyurethane elastomer; 15-20 parts by weight of aluminum diethylphosphinate; 10-15 parts by weight of melamine cyanurate; 3-5 parts by weight of epoxidized soybean oil; 2-4 parts by weight of hydroxyl-terminated polydimethylsiloxane; and 2-3 parts by weight of hydrolysis-resistant masterbatch. The anti-hydrolysis agent masterbatch is prepared by melt granulation of solid polymer anti-hydrolysis resin and thermoplastic polyurethane elastomer; the solid polymer anti-hydrolysis resin is prepared by reacting diphenylmethane-4,4'-diisocyanate and 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide in toluene solvent and then extruding to remove the toluene solvent. The epoxy-terminated polydimethylsiloxane is prepared by hydrosilylation reaction of hydrogen-terminated polydimethylsiloxane with a hydrogen mass fraction of 0.05% to 0.20% with allyl glycidyl ether under the action of platinum catalyst, followed by vacuum devolatilization to remove low molecular weight compounds.

2. The photoelectric signal transmission composite cable according to claim 1, characterized in that, The reactive slip buffer layer is made of the following raw materials in parts by weight: 100 parts by weight of thermoplastic polyurethane elastomer, 3.5 to 4 parts by weight of epoxidized soybean oil, and 3 to 3.5 parts by weight of epoxidized end-capped polydimethylsiloxane. The flame-retardant and hydrolysis-resistant outer sheath is made from the following raw materials in parts by weight: 100 parts by weight of thermoplastic polyurethane elastomer, 16-18 parts by weight of aluminum diethylphosphinate, 11-12 parts by weight of melamine cyanurate, 3.5-4 parts by weight of epoxidized soybean oil, 3-3.5 parts by weight of hydroxyl-terminated polydimethylsiloxane, and 2.5-2.8 parts by weight of hydrolysis-resistant masterbatch.

3. The photoelectric signal transmission composite cable according to claim 1, characterized in that, The optoelectronic composite cable core includes a stranded core wire formed by concentrically stranding insulated copper wire and quartz optical fiber, and a basic isolation layer formed by continuously wrapping polytetrafluoroethylene tape around the outside of the stranded core wire. The stranding pitch of the stranded core wire is 30-50 mm; the wrapping overlap of the polytetrafluoroethylene tape is 15%-30%; and the thickness of the base isolation layer is 0.05-0.1 mm.

4. A method for preparing a photoelectric signal transmission composite cable according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Insulated copper wire and quartz optical fiber are bundled together to obtain bundled core wire; polytetrafluoroethylene tape is wrapped around the outside of the bundled core wire to form a basic isolation layer, thus obtaining optoelectronic composite cable core. S2: Thermoplastic polyurethane elastomer, epoxidized soybean oil and epoxidized end-capped polydimethylsiloxane are mixed evenly to obtain a buffer layer premixed dry material. The buffer layer premixed dry material is fed into the first single screw extruder and extruded into a tube, which is then wrapped around the outside of the optoelectronic composite cable core obtained in S1 to form a reactive slip buffer layer, thus obtaining a cable core with a buffer layer. S3: The raw materials for preparing the flame-retardant and hydrolysis-resistant outer sheath, including the anti-hydrolysis agent masterbatch, are fed into a twin-screw extruder for dispersion and blending, extrusion, pelletizing, dehydration and drying to obtain the flame-retardant and hydrolysis-resistant outer sheath material; S4: The buffered cable core is continuously fed into the center of the die head of the second single-screw extruder. The flame-retardant and hydrolysis-resistant outer sheath material is fed into the second single-screw extruder, melted, plasticized, and extruded to cover the outside of the buffered cable core. After cooling and shaping, the photoelectric signal transmission composite cable is obtained.

5. The method for preparing the photoelectric signal transmission composite cable according to claim 4, characterized in that, In step S3, the twin-screw extruder is sequentially configured with zone one, zone two, zone three, natural exhaust section, vacuum exhaust section, zone four, and die head along the material conveying direction; The steps in S3 include: A portion of the thermoplastic polyurethane elastomer, aluminum diethylphosphinate, and melamine cyanurate are added to Zone 1 via the main feeder and conveyed to Zone 2. When the material enters Zone 2, epoxidized soybean oil is injected through the first injection port, forming an initial melt mixture in Zone 2. Subsequently, the remaining thermoplastic polyurethane elastomer is added to the initial melt mixture via the first side feeder and conveyed to Zone 3. When the material enters Zone 3, hydroxyl-terminated polydimethylsiloxane is injected through the second injection port for mixing and dispersion. After the material passes through the natural exhaust section and the vacuum exhaust section in sequence, the anti-hydrolysis agent masterbatch is added via the second side feeder before entering the metering conveying section of Zone 4. After entering Zone 4 with the material, it is dispersed and blended in the barrel of Zone 4, and finally extruded and granulated to obtain the flame-retardant and anti-hydrolysis outer sheath material. The first injection port is located in the second zone and downstream of the first melting and kneading section of the second zone; the feeding position of the first side feeder is located downstream of the first injection port and between the first injection port and the second injection port; the second injection port is located in the third zone; the feeding position of the second side feeder is located after the vacuum exhaust section and before the metering and conveying section of the fourth zone.

6. The method for preparing the photoelectric signal transmission composite cable according to claim 4, characterized in that, In step S2, the barrel temperature of the first single-screw extruder is controlled to be 160-180°C, and the thickness of the reactive slip buffer layer is 0.1-0.2 mm. In step S4, the die head of the second single-screw extruder adopts a tube-type die, and the draw ratio is controlled between 1.5 and 3.

0. The extrusion process parameters of the second single-screw extruder are: barrel temperature 140-155℃, die head temperature 150-160℃, and after coating, it is shaped and cooled in a cooling water tank at 15-20℃.

7. The method for preparing the photoelectric signal transmission composite cable according to claim 5, characterized in that, The anti-hydrolysis agent masterbatch is prepared in advance by including the following steps: (1) Add 100 parts by weight of diphenylmethane-4,4'-diisocyanate and 200 parts by weight of toluene into a reaction vessel and heat to reflux. Add 0.5 to 1.0 parts by weight of 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide, react for 4 to 6 hours and remove the generated carbon dioxide to obtain a polymer anti-hydrolysis mixture. (2) The polymer anti-hydrolysis mixture is extruded and the toluene solvent is removed, and then cooled and pelletized to obtain a solid polymer anti-hydrolysis resin; (3) Mix 40-60 parts by weight of the solid polymer anti-hydrolysis resin with 40-60 parts by weight of the thermoplastic polyurethane elastomer and melt granulate them through a twin-screw extruder to obtain the anti-hydrolysis agent masterbatch.

8. The method for preparing the photoelectric signal transmission composite cable according to claim 4, characterized in that, The epoxy-terminated polydimethylsiloxane is prepared in advance by including the following steps: (1) 100 parts by weight of hydrogen-capped polydimethylsiloxane with a hydrogen mass fraction of 0.05% to 0.20% and 8 to 30 parts by weight of allyl glycidyl ether were added to a reaction vessel for nitrogen purging. After stirring and mixing, the mixture was heated to 80 to 90°C to obtain a silicon-hydrogen reaction mixture premix. (2) Add 0.5 to 0.8 parts by weight of a platinum concentration of 2000 ppm isopropanol chloroplatinic acid solution to the aforementioned silane reaction mixture and react at 85 to 95°C for 3 to 5 hours to obtain crude epoxy silicone oil; (3) The crude epoxy silicone oil is fed into a de-devouring device and de-devoured under reduced pressure for 2 to 3 hours at an absolute pressure of 0.008 MPa and a temperature of 110 to 120°C to obtain the epoxy-terminated polydimethylsiloxane.

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