A biocompatible antimicrobial and flame retardant medical cable and a method of making the same

Abstract

The application discloses a kind of biocompatibility antibacterial flame-retardant medical cable and preparation method thereof, medical cable includes cable core and the sheath layer of cladding in cable core outside, sheath layer with thermoplastic polyurethane elastomer as matrix, and including resorcinol bis (diphenyl phosphate), piperazine pyrophosphate, zinc borate, antibacterial agent and synergist;Synergist is obtained by controlled polycondensation of tris (2-hydroxyethyl) isocyanurate and adipic acid, number average molecular weight is 700-1500.Cooperant has lower self migration ability, and its retained multiple hydroxyl groups can form dynamic, reversible multi-point intermolecular interaction with phosphonyl in resorcinol bis (diphenyl phosphate), to reduce the diffusion, migration and leaching tendency of flame-retardant component in thermoplastic polyurethane matrix, and with phosphorus-containing, nitrogen-containing flame-retardant component synergistically maintain good flame-retardant property.The obtained medical cable has flame-retardant, antibacterial and low migration characteristics, which is beneficial to improve long-term use stability and biocompatibility control level.

Description

Technical Field

[0001] This invention belongs to the field of cable technology and relates to a biocompatible antibacterial and flame-retardant medical cable and its preparation method. Background Technology

[0002] As medical equipment evolves towards digitalization, intelligence, and portability, various monitoring, diagnostic, treatment, and medical sensing devices typically require cables for transmitting electrical energy, signals, or data. Compared to ordinary cables, medical cables may frequently come into contact with patients, medical staff, or medical equipment during use. Therefore, in addition to requiring excellent insulation, flexibility, and mechanical properties, higher requirements are placed on the safety and biocompatibility of the cable materials.

[0003] Existing medical cables typically use polymer materials such as polyvinyl chloride (PVC), thermoplastic polyurethane elastomers, thermoplastic elastomers, or silicone rubber for their insulation or sheathing. These polymer materials possess good flexibility, abrasion resistance, and processing performance, meeting the requirements of repeated bending and long-term use in medical cables. However, polymer materials generally have a certain degree of flammability, posing a risk of combustion and flame spread under the influence of high temperatures, electric arcs, or external ignition sources generated by electrical faults. Therefore, to improve the safety of medical cables, it is usually necessary to modify their insulation or sheathing materials with flame retardant properties.

[0004] Currently, adding flame retardants to polymer matrices is a common method to improve the flame retardant properties of cable materials. Among them, organophosphorus and phosphorus-nitrogen additive flame retardants are widely used in polymer flame retardant modification because they can inhibit material combustion through gas-phase flame retardancy and condensed-phase char formation. However, some additive flame retardants are mainly dispersed in the polymer matrix through physical blending, lacking stable chemical bonding with the polymer molecular chains. During long-term use and exposure to temperature changes, repeated bending, or contact with external media, some flame-retardant components may gradually migrate to the material surface and undergo precipitation or leaching.

[0005] For ordinary cables, the migration or leaching of flame-retardant components mainly affects the long-term flame-retardant stability and surface properties of the material. However, for medical cables, which may come into frequent contact with patients, medical staff, or the medical environment, the requirements for controlling migratable and leached substances in the material are much higher. When flame-retardant components migrate or leach out from the polymer matrix, it may not only reduce the content of effective flame-retardant components inside the material, causing the flame-retardant performance to decline with prolonged use, but it may also increase the level of leached substances in the material, thereby increasing the difficulty of controlling the biocompatibility of medical cables.

[0006] Therefore, how to impart good flame retardant properties to medical cables while reducing the migration, precipitation, or leaching of flame retardant components during long-term use, and improving the stability of flame retardant components in the polymer matrix, thereby balancing the flame retardant properties and biocompatibility of medical cables, is a technical problem that existing medical cable materials need to solve. Summary of the Invention

[0007] The purpose of this invention is to provide a biocompatible antibacterial flame-retardant medical cable and its preparation method. By introducing a synergist with multi-site association ability, the migration of phosphorus-containing flame-retardant components is dynamically and reversibly inhibited, while the cable is endowed with antibacterial function, so as to achieve a balance between flame-retardant efficiency, antibacterial performance and low migration characteristics.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] In a first aspect, the present invention provides a biocompatible antibacterial and flame-retardant medical cable, comprising a cable core and a sheath layer covering the outside of the cable core, wherein the sheath layer comprises the following components in parts by weight: 100 parts of thermoplastic polyurethane elastomer, 6.5-7.5 parts of resorcinol bis(diphenyl phosphate), 3.0-4.0 parts of synergist, 4.5-5.5 parts of piperazine pyrophosphate, 1.0-1.5 parts of zinc borate, 0.30-0.45 parts of antibacterial agent, 0.15-0.25 parts of hindered phenolic antioxidant, and 0.10-0.20 parts of phosphite antioxidant;

[0010] The synergist is prepared by controlled polycondensation of tris(2-hydroxyethyl) isocyanurate and adipic acid, and the number average molecular weight of the synergist is 700-1500.

[0011] Preferably, the preparation method of the synergist includes the following steps:

[0012] S1. Mix tris(2-hydroxyethyl) isocyanurate and adipic acid, heat to 135-145℃ under nitrogen protection, and stir for 20-40 min to obtain a molten mixture;

[0013] S2. Add tetrabutyl titanate to the molten mixture, heat to 150-160°C, react for 50-70 minutes, and drain the water produced during the reaction.

[0014] S3. Heat to 175-185℃ and continue the reaction for 2-3 hours to allow tris(2-hydroxyethyl) isocyanurate to undergo a polycondensation reaction with adipic acid.

[0015] S4. Gradually reduce the pressure of the reaction system to 5-15 kPa, and continue the reaction at 175-180℃ for 30-60 min to remove residual moisture and low molecular weight volatiles.

[0016] S5. After the reaction is complete, the product is cooled under nitrogen protection, pulverized, and vacuum dried to obtain the synergist.

[0017] Preferably, the mass ratio of tris(2-hydroxyethyl) isocyanurate to adipic acid is 100:(45-50).

[0018] Preferably, the amount of tetrabutyl titanate added is 0.10%-0.15% of the mass of tris(2-hydroxyethyl) isocyanurate.

[0019] Preferably, the synergist has a hydroxyl value of 120-300 mgKOH / g and an acid value of no more than 15 mgKOH / g.

[0020] Preferably, the thermoplastic polyurethane elastomer is a polyether-type thermoplastic polyurethane elastomer.

[0021] Preferably, the antibacterial agent is silver-loaded zirconium phosphate.

[0022] In a second aspect, the present invention provides a method for preparing a biocompatible antibacterial and flame-retardant medical cable as described in the first aspect, comprising the following steps:

[0023] Y1. The thermoplastic polyurethane elastomer, synergist, piperazine pyrophosphate, zinc borate and antibacterial agent are dried separately. The dried thermoplastic polyurethane elastomer, synergist, piperazine pyrophosphate, zinc borate and antibacterial agent are premixed with hindered phenolic antioxidant and phosphite antioxidant to obtain a premix.

[0024] Y2. The premixed material is added to a twin-screw extruder for melt mixing, so that the thermoplastic polyurethane elastomer forms a continuous melt. Resorcinol bis(diphenyl phosphate) is added through the liquid feed port set in the middle and rear section of the twin-screw extruder, and melt mixing continues. After vacuum degassing, extrusion, cooling and pelletizing, the sheath material is obtained.

[0025] Y3. The sheath material is melted, extruded, and wrapped around the outside of the cable core. After cooling and shaping, the biocompatible antibacterial and flame-retardant medical cable is obtained.

[0026] Preferably, in step Y1, the thermoplastic polyurethane elastomer is dried at 100-105℃ for 2-4 hours, and the synergist is vacuum dried at 70-80℃ for 3-4 hours; in step Y2, the temperatures of each zone of the twin-screw extruder are 160-165℃, 170-175℃, 180-185℃, 185-190℃, 185-190℃, and 180-185℃ respectively.

[0027] Preferably, in step Y3, the extrusion temperature of the sheath material is 185-195℃, and the thickness of the resulting sheath layer is 0.35-0.50mm.

[0028] The beneficial effects of this invention are:

[0029] (1) This invention introduces a synergist obtained by controlled polycondensation of tris(2-hydroxyethyl) isocyanurate and adipic acid into a thermoplastic polyurethane elastomer sheath system. By controlling the degree of polycondensation, the resulting synergist has a specific oligomolecular weight and hydroxyl content. The multiple hydroxyl action sites in the synergist can form dynamic and reversible multi-point intermolecular interactions with the phosphoryl groups in resorcinol bis(diphenyl phosphate), thus restricting the free diffusion of resorcinol bis(diphenyl phosphate) in the thermoplastic polyurethane elastomer matrix. During the long-term use of medical cables, when resorcinol bis(diphenyl phosphate) diffuses in the polymer matrix, it can form a composite migration unit or a local multi-molecular association structure with the adjacent oligomer synergist, thereby increasing its effective movement size and improving the spatial resistance and frictional resistance it encounters when passing through polymer chain segments. At the same time, the oligomerized synergist itself has a lower migration ability than small molecule polyhydroxy compounds and can form a relatively stable multi-site action unit in the thermoplastic polyurethane elastomer matrix. This reduces the effective diffusion rate of resorcinol bis(diphenyl phosphate) in the sheath material, decreasing its tendency to migrate, precipitate, and leach to the sheath surface during long-term use, temperature changes, repeated bending, or contact with external media. This improves the long-term stability of phosphorus-based flame retardant components in the sheath material and helps reduce the level of migratable and leachable components in medical cable sheaths.

[0030] (2) The migration inhibition of resorcinol bis(diphenyl phosphate) in this invention utilizes the dynamic and reversible intermolecular interaction between the synergist and resorcinol bis(diphenyl phosphate). Under normal operating temperatures of medical cables, the aforementioned intermolecular interaction can restrict the movement of resorcinol bis(diphenyl phosphate); however, under high temperature or combustion conditions, as the temperature increases, the aforementioned interaction can weaken, dissociate, or rearrange, allowing the restricted resorcinol bis(diphenyl phosphate) to still participate in the thermal decomposition and flame retardant process of thermoplastic polyurethane elastomers. Simultaneously, the synergist itself contains a nitrogen-containing isocyanurate structure, which can produce a phosphorus-nitrogen synergistic effect with resorcinol bis(diphenyl phosphate) and piperazine pyrophosphate during combustion, and participate in char layer formation, while zinc borate further enhances the char layer. Therefore, this invention can reduce the migration tendency of phosphorus-based flame retardants at room temperature while retaining their flame retardant effect under high-temperature combustion conditions, achieving a balance between the long-term stability of the flame retardant component and the flame retardant performance during the combustion stage.

[0031] (3) By synergistically introducing a flame retardant system and a silver-loaded zirconium phosphate antibacterial agent into the thermoplastic polyurethane elastomer sheath, the present invention not only imparts good flame retardant and antibacterial properties to medical cables, but also reduces the migration and leaching tendency of flame retardant components in the sheath. This is beneficial to reduce the impact of migratable and leaching substances on the biosafety of materials, thereby improving the long-term stability and biocompatibility control level of medical cables. Detailed Implementation

[0032] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0033] The following descriptions of some of the raw materials used in the examples and comparative examples are as follows:

[0034] The thermoplastic polyurethane elastomer is a polyether-type thermoplastic polyurethane elastomer, specifically Lubrizol's ESTANE® 58300.

[0035] Resorcinol bis(diphenyl phosphate) (RDP) is sourced from Wuhan Jiyesheng Chemical Co., Ltd., and is of industrial grade.

[0036] Tris(2-hydroxyethyl) isocyanurate is sourced from Shandong Jianbang New Material Co., Ltd., and is of industrial grade.

[0037] Piperazine pyrophosphate (PAPP), CAS: 66034-17-1, sourced from Wuhan Jiyesheng Chemical Co., Ltd., industrial grade;

[0038] Zinc borate is sourced from Shandong Taixing New Material Co., Ltd., and is of industrial grade.

[0039] The antibacterial agent, silver-loaded zirconium phosphate, is sourced from Fujian Ruisen New Materials Co., Ltd., product model RS-LZY.

[0040] The hindered phenolic antioxidant is antioxidant 1010;

[0041] The antioxidant for phosphite is antioxidant 168.

[0042] Except for the raw materials explicitly mentioned above, all other raw materials not specifically mentioned are conventional industrial-grade products that can be easily obtained through commercial channels.

[0043] Example 1

[0044] A biocompatible antibacterial and flame-retardant medical cable includes a cable core and a sheath covering the outside of the cable core. By weight, the sheath comprises the following components: 100 parts thermoplastic polyurethane elastomer, 7.0 parts resorcinol bis(diphenyl phosphate), 3.5 parts synergist, 5.0 parts piperazine pyrophosphate, 1.2 parts zinc borate, 0.40 parts silver-loaded zirconium phosphate antibacterial agent, 0.20 parts antioxidant 1010, and 0.15 parts antioxidant 168.

[0045] The preparation method of the synergist includes the following steps:

[0046] S1. Tris(2-hydroxyethyl) isocyanurate and adipic acid are added to a reaction vessel according to a mass ratio of 100:47.5. Under nitrogen protection, the temperature is gradually raised to 140°C and stirred for 30 minutes to fully melt and mix the raw materials to obtain a molten mixture.

[0047] S2. Add tetrabutyl titanate to the molten mixture, wherein the amount of tetrabutyl titanate added is 0.12% of the mass of tris(2-hydroxyethyl) isocyanurate, then raise the temperature to 155°C, react for 60 min, and continuously drain the water generated during the reaction.

[0048] S3. Heat the reaction system to 180℃ and continue the reaction for 2.5h to allow tris(2-hydroxyethyl) isocyanurate to undergo further polycondensation with adipic acid.

[0049] S4. Gradually reduce the pressure of the reaction system to 10 kPa and continue the reaction at 178°C for 45 min to remove residual water and low molecular weight volatiles from the reaction system.

[0050] S5. After the reaction is complete, the product is cooled to room temperature under nitrogen protection, pulverized, and vacuum dried at 80°C to constant weight to obtain the synergist.

[0051] The synergist has a number-average molecular weight (Mn) of 1180, a hydroxyl value of 215 mgKOH / g, and an acid value of 10.8 mgKOH / g. The hydroxyl value was determined according to the method specified in HG / T 2709-2022, the acid value according to the method specified in HG / T 2708-1995, and the number-average molecular weight (Mn) was determined by gel permeation chromatography. The gel permeation chromatography test used tetrahydrofuran as the mobile phase, was calibrated with narrow molecular weight distribution polystyrene standards, and was detected using a differential refractive index detector. The mobile phase flow rate was 1.0 mL / min, the column temperature was 35℃, and the sample was fully dissolved in tetrahydrofuran and filtered through a 0.45 μm organic filter before injection. The number-average molecular weight (Mn) was calculated based on the obtained gel permeation chromatogram and the polystyrene standard curve. The obtained number-average molecular weight is the polystyrene equivalent number-average molecular weight.

[0052] The preparation of the sheath material and the medical cable includes the following steps:

[0053] Y1. The thermoplastic polyurethane elastomer is dried at 100°C for 3 hours, the synergist is vacuum dried at 75°C for 3.5 hours, piperazine pyrophosphate is vacuum dried at 80°C for 3 hours, zinc borate is vacuum dried at 80°C for 3 hours, and silver-loaded zirconium phosphate antibacterial agent is vacuum dried at 70°C for 3 hours. Weigh out 100 parts of the dried thermoplastic polyurethane elastomer, 3.5 parts of the synergist, 5.0 parts of piperazine pyrophosphate, 1.2 parts of zinc borate, 0.40 parts of silver-loaded zirconium phosphate antibacterial agent, 0.20 parts of antioxidant 1010, and 0.15 parts of antioxidant 168 according to the weight ratio, and premix for 8 minutes to obtain a premix.

[0054] Y2. The obtained premixed material is added to a twin-screw extruder for melt mixing. The screw speed of the twin-screw extruder is 200 r / min, and the temperatures of each zone are set to 162℃, 172℃, 182℃, 188℃, 188℃ and 182℃ respectively. After the thermoplastic polyurethane elastomer forms a continuous melt in the twin-screw extruder, 7.0 parts of resorcinol bis(diphenyl phosphate) are added through the liquid feed port set in the middle and rear section of the twin-screw extruder using a metering pump. Melt mixing continues to ensure that the components are fully mixed and dispersed. After vacuum degassing, extrusion, cooling and pelletizing, the sheath material is obtained.

[0055] Y3. Multiple tin-plated copper wires are twisted together to form a conductor. Insulating material is extruded from the outside of the conductor to form an insulating layer. The conductor and the insulating layer covering the outside of the conductor constitute the cable core. The sheath material obtained in step Y2 is added to a cable extruder, melted and extruded, and then wrapped around the outside of the cable core. The extrusion temperature of the sheath material is 190°C. After cooling and shaping, a biocompatible antibacterial and flame-retardant medical cable with a sheath layer thickness of 0.42 mm is obtained.

[0056] Example 2

[0057] A biocompatible antibacterial and flame-retardant medical cable includes a cable core and a sheath layer covering the outside of the cable core. By weight, the sheath layer comprises the following components: 100 parts thermoplastic polyurethane elastomer, 6.5 parts resorcinol bis(diphenyl phosphate), 3.0 parts synergist, 4.5 parts piperazine pyrophosphate, 1.0 part zinc borate, 0.30 parts silver-loaded zirconium phosphate antibacterial agent, 0.15 parts antioxidant 1010, and 0.10 parts antioxidant 168.

[0058] The preparation method of the synergist includes the following steps:

[0059] S1. Tris(2-hydroxyethyl) isocyanurate and adipic acid are added to a reaction vessel at a mass ratio of 100:45. The temperature is gradually raised to 135°C under nitrogen protection and stirred for 20 minutes to fully melt and mix the raw materials to obtain a molten mixture.

[0060] S2. Add tetrabutyl titanate to the molten mixture, wherein the amount of tetrabutyl titanate added is 0.10% of the mass of tris(2-hydroxyethyl) isocyanurate, then heat to 150°C, react for 50 min, and continuously drain the water generated during the reaction.

[0061] S3. Heat the reaction system to 175℃ and continue the reaction for 2 hours to allow tris(2-hydroxyethyl) isocyanurate to undergo further polycondensation with adipic acid.

[0062] S4. Gradually reduce the pressure of the reaction system to 5 kPa, and continue the reaction at 175°C for 30 min to remove residual water and low molecular weight volatiles from the reaction system.

[0063] S5. After the reaction is complete, the product is cooled to room temperature under nitrogen protection, pulverized, and vacuum dried at 80°C to constant weight to obtain the synergist.

[0064] The synergist has a number-average molecular weight (Mn) of 900, a hydroxyl value of 232 mgKOH / g, and an acid value of 9.6 mgKOH / g. The methods for determining the hydroxyl value, acid value, and number-average molecular weight (Mn) are the same as in Example 1.

[0065] The preparation method of the sheath material and the medical cable includes the following steps:

[0066] Y1. Dry the thermoplastic polyurethane elastomer at 100℃ for 3 hours, vacuum dry the synergist at 75℃ for 3 hours, vacuum dry the piperazine pyrophosphate at 80℃ for 3 hours, vacuum dry the zinc borate at 80℃ for 3 hours, and vacuum dry the silver-loaded zirconium phosphate antibacterial agent at 70℃ for 3 hours; weigh 100 parts of the dried thermoplastic polyurethane elastomer, 3.0 parts of the synergist, 4.5 parts of the piperazine pyrophosphate, 1.0 part of the zinc borate, 0.30 parts of the silver-loaded zirconium phosphate antibacterial agent, 0.15 parts of antioxidant 1010, and 0.10 parts of antioxidant 168 according to the weight ratio, and premix for 5 minutes to obtain a premix.

[0067] Y2. The obtained premixed material is added to a twin-screw extruder for melt mixing. The screw speed of the twin-screw extruder is 200 r / min, and the temperatures of each zone are set to 160℃, 170℃, 180℃, 185℃, 185℃ and 180℃ respectively. After the thermoplastic polyurethane elastomer forms a continuous melt in the twin-screw extruder, 6.5 parts of resorcinol bis(diphenyl phosphate) are added through the liquid feed port set in the middle and rear section of the twin-screw extruder using a metering pump. Melt mixing continues to ensure that the components are fully mixed and dispersed. After vacuum degassing, extrusion, cooling and pelletizing, the sheath material is obtained.

[0068] Y3. Multiple tinned copper wires are twisted together to form a conductor. Insulating material is extruded from the outside of the conductor to form an insulating layer. The conductor and the insulating layer covering the outside of the conductor constitute the cable core. The sheath material obtained in step Y2 is added to a cable extruder, melted and extruded, and then wrapped around the outside of the cable core. The extrusion temperature of the sheath material is 185°C. After cooling and shaping, a biocompatible antibacterial flame-retardant medical cable with a sheath layer thickness of 0.35 mm is obtained.

[0069] Example 3

[0070] A biocompatible antibacterial and flame-retardant medical cable includes a cable core and a sheath covering the outside of the cable core. By weight, the sheath comprises the following components: 100 parts thermoplastic polyurethane elastomer, 7.5 parts resorcinol bis(diphenyl phosphate), 4.0 parts synergist, 5.5 parts piperazine pyrophosphate, 1.5 parts zinc borate, 0.45 parts silver-loaded zirconium phosphate antibacterial agent, 0.25 parts antioxidant 1010, and 0.20 parts antioxidant 168.

[0071] The preparation method of the synergist includes the following steps:

[0072] S1. Tris(2-hydroxyethyl) isocyanurate and adipic acid are added to a reaction vessel at a mass ratio of 100:50. The temperature is gradually raised to 145°C under nitrogen protection and stirred for 40 minutes to fully melt and mix the raw materials to obtain a molten mixture.

[0073] S2. Add tetrabutyl titanate to the molten mixture, wherein the amount of tetrabutyl titanate added is 0.15% of the mass of tris(2-hydroxyethyl) isocyanurate, then heat to 160°C, react for 70 min, and continuously drain the water generated during the reaction.

[0074] S3. Heat the reaction system to 185℃ and continue the reaction for 3 hours to allow tris(2-hydroxyethyl) isocyanurate to undergo further polycondensation with adipic acid.

[0075] S4. Gradually reduce the pressure of the reaction system to 15 kPa and continue the reaction at 180°C for 60 min to remove residual water and low molecular weight volatiles from the reaction system.

[0076] S5. After the reaction is complete, the product is cooled to room temperature under nitrogen protection, pulverized, and vacuum dried at 80°C to constant weight to obtain the synergist.

[0077] The synergist has a number-average molecular weight (Mn) of 1450, a hydroxyl value of 198 mgKOH / g, and an acid value of 12.1 mgKOH / g. The methods for determining the hydroxyl value, acid value, and number-average molecular weight (Mn) are the same as in Example 1.

[0078] The preparation method of the sheath material and medical cable includes the following steps:

[0079] Y1. The thermoplastic polyurethane elastomer is dried at 105°C for 4 hours, the synergist is vacuum dried at 80°C for 4 hours, piperazine pyrophosphate is vacuum dried at 80°C for 3 hours, zinc borate is vacuum dried at 80°C for 3 hours, and the silver-loaded zirconium phosphate antibacterial agent is vacuum dried at 70°C for 3 hours. Weigh out 100 parts by weight of the dried thermoplastic polyurethane elastomer, 4.0 parts by weight of the synergist, 5.5 parts by weight of the piperazine pyrophosphate, 1.5 parts by weight of the zinc borate, 0.45 parts by weight of the silver-loaded zirconium phosphate antibacterial agent, 0.25 parts by weight of the antioxidant 1010, and 0.20 parts by weight of the antioxidant 168, and premix them for 10 minutes to obtain a premix.

[0080] Y2. The obtained premixed material is added to a twin-screw extruder for melt mixing. The screw speed of the twin-screw extruder is 200 r / min, and the temperatures of each zone are set to 165℃, 175℃, 185℃, 190℃, 190℃ and 185℃ respectively. After the thermoplastic polyurethane elastomer forms a continuous melt in the twin-screw extruder, 7.5 parts of resorcinol bis(diphenyl phosphate) are added through the liquid feed port located in the middle and rear section of the twin-screw extruder using a metering pump. Melt mixing continues to ensure that the components are fully mixed and dispersed. After vacuum degassing, extrusion, cooling and pelletizing, the sheath material is obtained.

[0081] Y3. Multiple tinned copper wires are twisted together to form a conductor. Insulating material is extruded from the outside of the conductor to form an insulating layer. The conductor and the insulating layer covering the outside of the conductor constitute the cable core. The sheath material obtained in step Y2 is added to a cable extruder, melted and extruded, and then wrapped around the outside of the cable core. The extrusion temperature of the sheath material is 195°C. After cooling and shaping, a biocompatible antibacterial flame-retardant medical cable with a sheath layer thickness of 0.50 mm is obtained.

[0082] Comparative Example 1

[0083] Compared with Example 1, the difference in this comparative example is that no synergist is added to the sheath layer.

[0084] By weight, the sheath layer comprises 100 parts of thermoplastic polyurethane elastomer, 7.0 parts of resorcinol bis(diphenyl phosphate), 5.0 parts of piperazine pyrophosphate, 1.2 parts of zinc borate, 0.40 parts of silver-loaded zirconium phosphate antibacterial agent, 0.20 parts of antioxidant 1010, and 0.15 parts of antioxidant 168.

[0085] Except for the absence of a synergist in step Y1, the other raw material pretreatment conditions, mixing conditions, twin-screw melt mixing conditions, the addition method of resorcinol bis(diphenyl phosphate), and the cable sheath extrusion conditions were all the same as in Example 1, and the medical cable of Comparative Example 1 was obtained.

[0086] Comparative Example 2

[0087] Compared with Example 1, the difference in this comparative example is that tris(2-hydroxyethyl) isocyanurate is used to replace the synergist in Example 1 by weight.

[0088] By weight, the sheath layer comprises 100 parts of thermoplastic polyurethane elastomer, 7.0 parts of resorcinol bis(diphenyl phosphate), 3.5 parts of tris(2-hydroxyethyl) isocyanurate, 5.0 parts of piperazine pyrophosphate, 1.2 parts of zinc borate, 0.40 parts of silver-loaded zirconium phosphate antibacterial agent, 0.20 parts of antioxidant 1010, and 0.15 parts of antioxidant 168.

[0089] Tris(2-hydroxyethyl) isocyanurate was vacuum dried at 75°C for 3.5 h and then added to the solid raw material premix in step Y1. Except for replacing 3.5 parts by weight of synergist with 3.5 parts by weight of tris(2-hydroxyethyl) isocyanurate, the other preparation steps and process conditions were the same as in Example 1, and the medical cable of Comparative Example 2 was obtained.

[0090] Comparative Example 3

[0091] Compared with Example 1, the difference in this comparative example is that a tri(2-hydroxyethyl) isocyanurate-adipic acid condensation product with a lower number average molecular weight is used instead of the synergist in Example 1.

[0092] The preparation method of the low molecular weight polycondensation product is as follows:

[0093] S1. Tris(2-hydroxyethyl) isocyanurate and adipic acid are added to a reaction vessel at a mass ratio of 100:40. The mixture is heated to 140°C under nitrogen protection and stirred for 30 minutes to ensure that the raw materials are fully melted and mixed.

[0094] S2. Add tetrabutyl titanate at 0.12% of the mass of tris(2-hydroxyethyl) isocyanurate, heat to 155℃ and react for 50 min, then drain the water produced in the reaction.

[0095] S3, raise the temperature to 170℃ and continue the reaction for 1.0 h;

[0096] S4. Gradually reduce the pressure of the reaction system to 15 kPa, and continue the reaction at 170°C for 20 min to remove residual moisture and low molecular weight volatiles;

[0097] S5. Cool to room temperature under nitrogen protection, pulverize the obtained product, and vacuum dry it at 80°C to constant weight to obtain a low molecular weight polycondensation product.

[0098] The low molecular weight condensation product has a number-average molecular weight (Mn) of approximately 620, a hydroxyl value of approximately 300 mgKOH / g, and an acid value of approximately 44 mgKOH / g. The methods for determining the hydroxyl value, acid value, and number-average molecular weight (Mn) are the same as in Example 1.

[0099] The 3.5 parts by weight of synergist in Example 1 were replaced with 3.5 parts by weight of the aforementioned low molecular weight polycondensation product. Except for the above differences, the remaining sheath layer composition, raw material pretreatment steps, melt mixing steps, and sheath extrusion steps were the same as in Example 1, and the medical cable of Comparative Example 3 was obtained.

[0100] Comparative Example 4

[0101] Compared with Example 1, the difference in this comparative example is that a tri(2-hydroxyethyl) isocyanurate-adipic acid condensation product with a higher number average molecular weight is used instead of the synergist in Example 1.

[0102] The preparation method of the high molecular weight polycondensation product is as follows:

[0103] S1. Tris(2-hydroxyethyl) isocyanurate and adipic acid are added to a reaction vessel at a mass ratio of 100:47.5. The mixture is heated to 140°C under nitrogen protection and stirred for 30 minutes to fully melt and mix the raw materials.

[0104] S2. Add tetrabutyl titanate at 0.12% of the mass of tris(2-hydroxyethyl) isocyanurate, heat to 155℃ and react for 60 min, then drain the water produced in the reaction.

[0105] S3, raise the temperature to 182℃ and continue the reaction for 3.0 h;

[0106] S4. Gradually reduce the pressure of the reaction system to 8 kPa, and continue the reaction at 180°C for 60 min to remove residual moisture and low molecular weight volatiles;

[0107] S5. Cool to room temperature under nitrogen protection, pulverize the obtained product, and vacuum dry it at 80°C to constant weight to obtain a high molecular weight polycondensation product.

[0108] The high molecular weight condensation product has a number-average molecular weight (Mn) of approximately 1700, a hydroxyl value of approximately 214 mgKOH / g, and an acid value of approximately 9 mgKOH / g. The methods for determining the hydroxyl value, acid value, and number-average molecular weight (Mn) are the same as in Example 1.

[0109] The 3.5 parts by weight of synergist in Example 1 were replaced with 3.5 parts by weight of the aforementioned high molecular weight polycondensation product. Except for the above differences, the remaining sheath layer composition, raw material pretreatment steps, melt mixing steps, and sheath extrusion steps were the same as in Example 1, and the medical cable of Comparative Example 4 was obtained.

[0110] Test case

[0111] The following performance tests were performed on the medical cable sheath materials prepared in Examples 1-3 and Comparative Examples 1-4.

[0112] Test Example 1: RDP Leaching Migration Performance Test

[0113] The sheath materials obtained in Examples 1-3 and Comparative Examples 1-4 were hot-pressed into sheets with a thickness of approximately 1.0 mm on a flat vulcanizing machine at 190°C and 10 MPa, and then cut into samples of approximately 10 mm × 10 mm. The samples were conditioned at 23±2°C and 50±5% relative humidity for 24 h. Then, 5.00 g of sample was accurately weighed and placed in a stoppered glass container. A 50% (v / v) ethanol aqueous solution was added as the extraction medium at a liquid-to-solid ratio of 20 mL / g. The container was sealed and placed in a constant-temperature shaker at 37±1°C, and the mixture was shaken and extracted at 60 r / min. Two extraction times were set: 24 h and 72 h, with independent samples used for each extraction time. After extraction, the extract was collected, filtered through a 0.45 μm organic filter membrane, and the content of resorcinol bis(diphenyl phosphate) (RDP) in the extract was determined by high-performance liquid chromatography (HPLC). A C18 reversed-phase column (4.6 mm × 250 mm, 5 μm particle size) was used. The mobile phase was a mixture of methanol and 5 mmol / L ammonium acetate aqueous solution (95:5, volume ratio). Isocratic elution was employed at a flow rate of 1.0 mL / min. The column temperature was 40℃. The UV detection wavelength was 230 nm. The injection volume was 10 μL. A series of standard solutions were prepared using RDP standards, and an external standard curve was established with RDP concentration as the x-axis and the corresponding peak area as the y-axis. RDP leaching amount was calculated using the following formula: RDP leaching amount (μg / g) = C × V × D / m. Where C is the mass concentration of RDP in the extract (μg / mL); V is the volume of the extract (mL); D is the dilution factor; and m is the mass of the sample before leaching (g). Three parallel samples were prepared for each group of samples, and the average value was taken.

[0114] The test results are shown in Table 1.

[0115] Table 1

[0116]

[0117] As shown in Table 1, the leaching amounts of resorcinol bis(diphenyl phosphate) in Examples 1-3 were significantly lower than those in Comparative Examples 1-3, indicating that the use of tris(2-hydroxyethyl) isocyanurate-adipic acid oligomer synergists with suitable number-average molecular weight can effectively reduce the migration and leaching of resorcinol bis(diphenyl phosphate) in the thermoplastic polyurethane matrix. Among them, Comparative Example 1, without the addition of a synergist, had the highest leaching amount; Comparative Example 2, after directly adding tris(2-hydroxyethyl) isocyanurate, showed a decrease in leaching amount, but it was still significantly higher than that in Examples 1-3. This indicates that although small molecule polyhydroxy compounds can produce certain intermolecular interactions with resorcinol bis(diphenyl phosphate), their small molecular size and strong migration ability limit the long-term migration of resorcinol bis(diphenyl phosphate). Comparative Example 3 used a low molecular weight condensation product with a number average molecular weight of approximately 620. Its acid value was higher than that of the examples. The presence of residual carboxyl groups may further enhance the polar intermolecular interactions in the system. However, its leaching amounts at 24 h and 72 h were still significantly higher than those of Examples 1-3. This indicates that when the synergist molecular size is too small, even with a large number of polar interaction sites, the synergist itself and the local associated structures it participates in still have high diffusion capabilities, making it difficult to effectively inhibit the long-term migration of resorcinol bis(diphenyl phosphate). Comparative Example 4 used a high molecular weight condensation product with a number average molecular weight of approximately 1700. Its resorcinol bis(diphenyl phosphate) leaching amount was further reduced, indicating that further increasing the synergist molecular size is beneficial to reducing its own and related associated structures' migration capabilities. However, as shown in Table 2, the further enhancement of migration inhibition does not necessarily lead to a simultaneous improvement in flame retardant performance.

[0118] Test Example 2: Flame Retardant Performance Test Before and After Immersion

[0119] The limiting oxygen index (LOI) of the sheath materials in Examples 1-3 and Comparative Examples 1-4 was tested according to GB / T 2406.2-2009, "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test". Each sheath material was hot-pressed on a flat vulcanizing machine at 190℃ and 10 MPa to prepare strip-shaped specimens with a length of 100 mm, a width of 10 mm, and a thickness of 4.0 mm. The specimens were conditioned at 23±2℃ and 50±5% relative humidity for 24 h, and the limiting oxygen index before impregnation was determined according to the method specified in GB / T 2406.2-2009, and recorded as LOI0. Another specimen of the same specifications was added to a 50% (v / v) ethanol aqueous solution at a liquid-to-solid ratio of 20 mL / g, and extracted at 37±1℃ with shaking at 60 r / min for 72 h. After extraction, the sample was removed, and the surface was quickly rinsed with deionized water. The surface moisture was then absorbed with filter paper, and the sample was conditioned at 23±2℃ and 50±5% relative humidity for 24 h. The limiting oxygen index (LOI) was then measured after 72 h of extraction using the same method. 72 Limiting oxygen index (LOI) retention rate is calculated using the following formula: LOI retention rate (%) = (LOI... 72 / LOI0)×100%. Three parallel samples were tested for each group of samples, and the average value of the results was taken. The test results are shown in Table 2.

[0120] Table 2

[0121]

[0122] As shown in Table 2, Examples 1-3 all exhibited high initial limiting oxygen index (LOI), and the LOI decreased only slightly after 72 h of extraction treatment, with a retention rate of over 95%. This indicates that the present invention, using an oligomer synergist of suitable molecular weight, can maintain the good flame retardant properties of the sheath material while reducing the migration and leaching of resorcinol bis(diphenyl phosphate). In Comparative Examples 1-3, as the synergist gradually changed from no synergist and small molecule tris(2-hydroxyethyl) isocyanurate to a low molecular weight polycondensation product, the LOI and retention rate after extraction gradually increased, corresponding to the trend of gradually decreasing resorcinol bis(diphenyl phosphate) leaching amount in Table 1. Although Comparative Example 4 exhibited a lower resorcinol bis(diphenyl phosphate) leaching amount and a higher LOI retention rate, its initial limiting oxygen index was lower than that of Examples 1-3. This indicates that while the migration inhibition effect can be further enhanced when the synergist molecular size increases, the flame retardant performance does not improve accordingly. This suggests that further increasing the molecular weight of the synergist does not yield a corresponding overall performance gain. This may be because high molecular weight synergists exert stronger restrictions on the molecular motion of resorcinol bis(diphenyl phosphate) and its redistribution under high-temperature conditions. Therefore, controlling the number-average molecular weight of the synergist within a suitable range is more beneficial for balancing migration inhibition under room temperature conditions with flame retardant response under high-temperature combustion conditions.

[0123] In summary, this invention obtains an oligomer synergist with suitable molecular size and retaining multiple hydroxyl groups through controlled polycondensation of tris(2-hydroxyethyl) isocyanurate and adipic acid. This synergist is then used in conjunction with resorcinol bis(diphenyl phosphate), piperazine pyrophosphate, and zinc borate in thermoplastic polyurethane sheathing systems. The oligomer synergist utilizes its low self-migration ability and the dynamic, reversible multi-point intermolecular interactions between the hydroxyl groups and the phosphoryl groups in resorcinol bis(diphenyl phosphate) to reduce the diffusion, migration, and leaching of resorcinol bis(diphenyl phosphate) in the sheathing material. Simultaneously, by controlling the molecular weight of the synergist within a suitable range, insufficient migration restriction due to excessively small molecular size can be avoided, while excessive constraint due to excessively large molecular size can be reduced. This achieves a balance between migration inhibition of resorcinol bis(diphenyl phosphate) at room temperature and effective flame retardant response during high-temperature combustion. By combining piperazine pyrophosphate, zinc borate, and silver-loaded zirconium phosphate antibacterial agents, the resulting medical cable sheath can have good flame retardant stability, antibacterial properties, and a low tendency for flame retardant components to leach out, which is beneficial to improving the long-term service stability and biocompatibility control level of medical cables.

[0124] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A biocompatible antibacterial and flame-retardant medical cable, comprising a cable core and a sheath covering the outside of the cable core, characterized in that, The sheath layer comprises the following components in parts by weight: 100 parts thermoplastic polyurethane elastomer, 6.5-7.5 parts resorcinol bis(diphenyl phosphate), 3.0-4.0 parts synergist, 4.5-5.5 parts piperazine pyrophosphate, 1.0-1.5 parts zinc borate, 0.30-0.45 parts antibacterial agent, 0.15-0.25 parts hindered phenolic antioxidant, and 0.10-0.20 parts phosphite antioxidant; The synergist is prepared by controlled polycondensation of tris(2-hydroxyethyl) isocyanurate and adipic acid, and the number average molecular weight of the synergist is 700-1500.

2. The biocompatible antibacterial and flame-retardant medical cable according to claim 1, characterized in that, The preparation method of the synergist includes the following steps: S1. Mix tris(2-hydroxyethyl) isocyanurate and adipic acid, heat to 135-145℃ under nitrogen protection, and stir for 20-40 min to obtain a molten mixture; S2. Add tetrabutyl titanate to the molten mixture, heat to 150-160°C, react for 50-70 minutes, and drain the water produced during the reaction. S3. Heat to 175-185℃ and continue the reaction for 2-3 hours to allow tris(2-hydroxyethyl) isocyanurate to undergo a polycondensation reaction with adipic acid. S4. Gradually reduce the pressure of the reaction system to 5-15 kPa, and continue the reaction at 175-180℃ for 30-60 min to remove residual moisture and low molecular weight volatiles. S5. After the reaction is complete, the product is cooled under nitrogen protection, pulverized, and vacuum dried to obtain the synergist.

3. The biocompatible antibacterial and flame-retardant medical cable according to claim 2, characterized in that, The mass ratio of the tris(2-hydroxyethyl) isocyanurate to adipic acid is 100:(45-50).

4. The biocompatible antibacterial and flame-retardant medical cable according to claim 2, characterized in that, The amount of tetrabutyl titanate added is 0.10%-0.15% of the mass of tris(2-hydroxyethyl) isocyanurate.

5. The biocompatible antibacterial and flame-retardant medical cable according to claim 1, characterized in that, The synergist has a hydroxyl value of 120-300 mg KOH / g and an acid value of no more than 15 mg KOH / g.

6. The biocompatible antibacterial and flame-retardant medical cable according to claim 1, characterized in that, The thermoplastic polyurethane elastomer is a polyether-type thermoplastic polyurethane elastomer.

7. The biocompatible antibacterial and flame-retardant medical cable according to claim 1, characterized in that, The antibacterial agent is silver-loaded zirconium phosphate.

8. A method for preparing a biocompatible antibacterial and flame-retardant medical cable according to any one of claims 1-7, characterized in that, Includes the following steps: Y1. The thermoplastic polyurethane elastomer, synergist, piperazine pyrophosphate, zinc borate and antibacterial agent are dried separately. The dried thermoplastic polyurethane elastomer, synergist, piperazine pyrophosphate, zinc borate and antibacterial agent are premixed with hindered phenolic antioxidant and phosphite antioxidant to obtain a premix. Y2. The premixed material is added to a twin-screw extruder for melt mixing, so that the thermoplastic polyurethane elastomer forms a continuous melt. Resorcinol bis(diphenyl phosphate) is added through the liquid feed port set in the middle and rear section of the twin-screw extruder, and melt mixing continues. After vacuum degassing, extrusion, cooling and pelletizing, the sheath material is obtained. Y3. The sheath material is melted, extruded, and wrapped around the outside of the cable core. After cooling and shaping, the biocompatible antibacterial and flame-retardant medical cable is obtained.

9. The method for preparing a biocompatible antibacterial and flame-retardant medical cable according to claim 8, characterized in that, In step Y1, the thermoplastic polyurethane elastomer is dried at 100-105℃ for 2-4 hours, and the synergist is vacuum dried at 70-80℃ for 3-4 hours; in step Y2, the temperatures of each zone of the twin-screw extruder are 160-165℃, 170-175℃, 180-185℃, 185-190℃, 185-190℃, and 180-185℃ respectively.

10. The method for preparing a biocompatible antibacterial and flame-retardant medical cable according to claim 8, characterized in that, In step Y3, the extrusion temperature of the sheath material is 185-195℃, and the thickness of the resulting sheath layer is 0.35-0.50mm.

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