A medical catheter material and its preparation method

Abstract

This invention relates to a medical catheter material and its preparation method, belonging to the field of silicone rubber technology. The material is based on a two-component liquid silicone rubber, prepared by introducing a hydrophilic modifier with a specific structure and using a platinum-catalyzed addition vulcanization system. The hydrophilic modifier is synthesized through hydrosilylation and ring-opening reactions, possessing double active double bonds and terminal siloxane segments. This allows it to be firmly anchored to the cross-linked network via covalent bonds during vulcanization, fundamentally avoiding the risks of small molecule migration or coating peeling. This ensures both the hydrophilicity of the polyoxyethylene ether segments and the mechanical integrity of the silicone rubber main network, enabling the catheter to achieve significant hydrophilicity while maintaining excellent tensile strength, tear resistance, and creep resistance.

Description

Technical Field

[0001] This invention belongs to the field of silicone rubber technology, specifically relating to a medical catheter material and its preparation method. Background Technology

[0002] Medical catheters are indispensable key instruments in modern medical practice, widely used in areas such as intravenous infusion, drainage, interventional therapy, monitoring, and nutritional support. Their core function is to establish a channel between the internal and external environments of the human body to deliver fluids, gases, and drugs, or to perform specific diagnostic and therapeutic procedures. Therefore, the biocompatibility, physical properties, and ease of use of catheter materials directly affect the effectiveness of diagnosis and treatment and patient safety.

[0003] Currently, medical catheters are made of various materials, mainly including polyvinyl chloride (PVC), polyethylene (PE), polyurethane, and silicone rubber. Among them, silicone rubber, with its excellent biocompatibility, superior chemical stability, resistance to biological aging, and wide temperature tolerance range, has become the preferred material for long-term implantation and highly sensitive applications. However, the inherent strong hydrophobic properties of silicone rubber have become a major bottleneck in its clinical application. This property results in significant frictional resistance when the catheter is inserted into the human body, which not only increases patient pain and operational difficulty but may also damage blood vessels or tissue linings. More importantly, the hydrophobic surface readily and non-specifically adsorbs proteins, lipids, and bacteria, forming biofilms that can lead to serious complications such as thrombosis and infection, greatly limiting its safety and effectiveness for long-term use.

[0004] To overcome the hydrophobicity problem of silicone rubber, existing technologies mainly focus on two major approaches: surface modification and bulk modification.

[0005] Surface coating technology: This method typically involves coating the surface of the molded silicone rubber conduit with a layer of hydrophilic polymer material. This technology can efficiently and significantly reduce the surface contact angle, achieving a water-based lubrication effect. However, its fundamental drawback lies in the risk of coating peeling and detachment. Detached coating fragments not only lead to lubrication failure but may also act as foreign objects, causing inflammation or embolism, posing serious safety hazards.

[0006] Bulk modification technology: This method aims to achieve overall hydrophilicity of the material by adding hydrophilic components to the raw silicone rubber. This can be further subdivided into two categories:

[0007] Non-reactive internal addition: This method involves directly and physically blending hydrophilic small molecules or polymers into the rubber compound. While simple, the added hydrophilic components have poor compatibility with the hydrophobic silicone rubber matrix. After vulcanization and during long-term use, they can migrate and precipitate to the surface due to thermodynamic forces. This migration not only makes the hydrophilic effect unsustainable, but more critically, the precipitated substances may enter the human body environment, posing a biotoxic risk. Simultaneously, the voids left by migration can disrupt the uniformity of the material structure, leading to a decline in mechanical properties.

[0008] Reactive internal addition: To overcome the migration problem, researchers have developed hydrophilic materials that can participate in vulcanization, such as vinyl-containing polyether macromonomers. Anchoring these macromonomers to the crosslinked network of silicone rubber via covalent bonds theoretically eliminates migration completely, ensuring extremely high safety. However, in practical applications, it has been found that although the migration problem is solved, the long polyether chains are incompatible with the flexible siloxane backbone. This microscopic phase separation causes the polymer chains to coil and shrink within the system, preventing them from effectively extending and severely interfering with the inherent crosslinked network of silicone rubber. Macroscopically, this manifests as a sharp deterioration in the material's tear resistance and intensified stress relaxation creep under internal stress, making the catheter prone to deformation and crushing during long-term placement, severely affecting its dimensional stability and safety in use.

[0009] In summary, existing technologies all suffer from irreconcilable contradictions: coating and physical blending methods are prone to migration and detachment, while existing reactive copolymerization methods may impair mechanical properties. Therefore, developing a hydrophilic modification technology that can prevent migration through strong chemical bonding and achieve good compatibility with the silicone rubber matrix without damaging or even optimizing its mechanical properties has become a pressing technical challenge in this field. Summary of the Invention

[0010] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a medical catheter material and a method for preparing the same.

[0011] The objective of this invention can be achieved through the following technical solutions:

[0012] A medical catheter material is formed by co-curing a two-component silicone rubber raw material with a hydrophilic modifier. The hydrophilic modifier is prepared by the following method:

[0013] Step A1: Mix the single-ended hydrogen-containing silicone oil, allyl epoxy polyoxyethylene polyether and toluene, heat to 90-100℃ under nitrogen protection, slowly add Karstedt catalyst and stir for 3.5-4.5h. After the reaction is completed, remove toluene by rotary evaporation under reduced pressure to obtain the epoxy intermediate.

[0014] Furthermore, the molar ratio of silane groups in the single-ended hydrogen-containing silicone oil to allyl groups in the allyl epoxy polyoxyethylene polyether is 1:1, the platinum content of the Karstedt catalyst is 30-40 ppm of both, and the allyl epoxy polyoxyethylene polyether undergoes hydrosilylation with the single-ended hydrogen-containing silicone oil.

[0015] Furthermore, the average molecular weight of allyl epoxy polyoxyethylene polyether is 400-500. At this molecular weight, the polyoxyethylene ether segments maintain good hydrophilicity, and after being modified with single-end hydrogen-containing silicone oil, the molecular chains are not easily coiled or folded.

[0016] Furthermore, the room temperature viscosity of single-ended hydrogen-containing silicone oil is 50-100 mm. 2 / s, silicone oils within this viscosity range exhibit good reactivity, while their moderate molecular weight range provides excellent modification effects on polyoxyethylene ether segments.

[0017] Step A2: Mix the epoxy intermediate, divinyl ethylene glycol and dioxane, add tetrabutylammonium bromide, heat to 55-70℃ and stir for 8-11 hours. After the reaction is completed, remove the dioxane by rotary evaporation under reduced pressure to obtain the hydrophilic modifier.

[0018] Furthermore, the molar ratio of epoxy content in the epoxy intermediate to that in divinyl glycol is 1:0.52-0.55, and the tetrabutylammonium bromide content is 0.6-0.9 wt% of both. The epoxy group at the end of the epoxy intermediate molecule undergoes ring-opening with divinyl glycol.

[0019] Preferably, the hydrophilic modifier is 12-18 wt% of the two-component silicone rubber raw material. The catheter material made with this co-vulcanization ratio has good wettability, meets the requirements of conventional catheter implantation, and maintains good overall performance.

[0020] The preparation method of the medical catheter material is as follows: the two-component silicone rubber raw material and hydrophilic modifier are mixed and degassed under vacuum, and then injection molded, vulcanized and shaped, and demolded and sterilized in sequence to obtain the medical catheter material.

[0021] Furthermore, the vulcanization molding temperature is 155-165℃, and the time is 75-90s.

[0022] The beneficial effects of this invention are:

[0023] This invention, through innovative molecular structure, designs and synthesizes a hydrophilic modifier with a specific architecture. This modifier is firmly integrated into the crosslinked network of silicone rubber via a platinum-catalyzed addition reaction. This design fundamentally solves the industry problem of balancing hydrophilicity, mechanical properties, and long-term stability in traditional hydrophilic modification technologies. Specific advantages are as follows:

[0024] The siloxane segments at the ends of the hydrophilic modifier exhibit excellent thermodynamic compatibility with the matrix, allowing the hydrophilic branches rich in polyoxyethylene ethers to fully extend and expose within the cross-linked network. This significantly reduces the contact angle of the material surface, endowing the conduit with durable and highly efficient hydrophilic lubrication properties. Simultaneously, because the hydrophilic components are covalently anchored within the three-dimensional network, performance degradation and biosafety risks caused by small molecule migration or coating detachment during use are completely avoided.

[0025] Furthermore, the double active double bonds of this modifier act as anchor points to the main network chain, while the flexible hydrophilic segments are suspended as side chains. This configuration effectively avoids directly embedding incompatible rigid segments into the siloxane main chain, which serves as the primary load-bearing structure. Therefore, the inherent crosslinking network integrity of silicone rubber remains intact, and its excellent tensile strength, elongation at break, and tear strength are preserved to the maximum extent, overcoming the material embrittlement and mechanical degradation problems caused by conventional copolymerization modification.

[0026] Furthermore, the uniform distribution of hydrophilic segments and the flexible suspension structure significantly reduce the internal stress caused by microscopic phase separation, effectively suppressing molecular chain slippage and rearrangement under continuous load. This characteristic directly translates into a significant improvement in the material's resistance to stress relaxation and creep, which is of crucial clinical significance for medical catheters that require long-term placement and maintenance of luminal morphology and functional stability.

[0027] This technical solution exhibits good compatibility with mainstream two-component liquid silicone rubber injection molding processes, eliminating the need for complex post-processing steps and making it suitable for large-scale industrial production. The prepared catheter body is hydrophilic, eliminating the risk of surface coating wear and failure, and due to the absence of small molecule precipitation, it demonstrates excellent biocompatibility. Cytotoxicity test results meet the highest safety standards for relevant medical devices. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: Preparation of medical catheter materials, the specific implementation method is as follows:

[0030] I. Preparation of hydrophilic modifiers

[0031] Step A1: Take single-ended hydrogen-containing silicone oil (raw material information: RH-H222-10, room temperature viscosity 65 mm). 2 / s, with a silane content of 0.032wt%) and allyl epoxy polyoxyethylene polyether (raw material information: PR-801, average molecular weight 400) were added according to the equimolar ratio of silane content and allyl content. Toluene, with a weight of 0.7 times the total weight of the two, was added and stirred until homogeneous. Nitrogen gas was introduced for protection and the temperature was raised to 90°C. Karstedt catalyst (raw material platinum content of 5000ppm) was added slowly at a platinum concentration of 30ppm in the raw material and stirred for 3.8h. After the reaction was completed, toluene was removed by rotary evaporation under reduced pressure to obtain the epoxy intermediate.

[0032] Step A2: Take epoxy intermediate and divinyl ethylene glycol, with the epoxy content of epoxy intermediate and the molar ratio of divinyl ethylene glycol being 1:0.52. Add 1.2 times the weight of dioxane to both and stir to mix well. Then, add 0.6 wt% of tetrabutylammonium bromide to the raw materials and mix. Heat to 55°C and stir to react for 9 hours. After the reaction is completed, remove dioxane by rotary evaporation under reduced pressure to obtain the hydrophilic modifier.

[0033] II. Preparation of Medical Catheter Materials

[0034] Take two-component silicone rubber raw material (raw material information: HY-921), mix its A component and B component at a weight ratio of 1:1.2, add more than 12wt% of the hydrophilic modifier prepared from the two-component silicone rubber raw material and mix well, vacuum degas for 10 min, then send it into the injection molding equipment, injection molded at 20±0.5MPa, then vulcanized at 155℃ for 75 s, and sterilized after demolding to obtain medical catheter material.

[0035] Example 2: Preparation of medical catheter materials, the specific implementation method is as follows:

[0036] I. Preparation of hydrophilic modifiers

[0037] Step A1: Take single-ended hydrogen-containing silicone oil (raw material information: RH-H222-10, room temperature viscosity 65 mm). 2 / s, with a silane content of 0.032wt%) and allyl epoxy polyoxyethylene polyether (raw material information: PR-801, average molecular weight 400) were added according to the equimolar ratio of silane content and allyl content. Toluene was added at 0.75 times the total weight of the two and stirred until well mixed. Nitrogen gas was introduced for protection and the temperature was raised to 90°C. Karstedt catalyst (raw material platinum content of 5000ppm) was slowly added at a platinum concentration of 40ppm in the raw material and stirred for 3.5h. After the reaction was completed, toluene was removed by rotary evaporation under reduced pressure to obtain the epoxy intermediate.

[0038] Step A2: Take epoxy intermediate and divinyl ethylene glycol, with the epoxy content of epoxy intermediate and the molar ratio of divinyl ethylene glycol being 1:0.52. Add 1.2 times the weight of dioxane to both and stir to mix well. Then, add 0.7 wt% of tetrabutylammonium bromide to the raw materials and mix. Heat to 60°C and stir to react for 8 hours. After the reaction is completed, remove dioxane by rotary evaporation under reduced pressure to obtain the hydrophilic modifier.

[0039] II. Preparation of Medical Catheter Materials

[0040] Take two-component silicone rubber raw material (raw material information: HY-921), mix its A component and B component at a weight ratio of 1:1.3, add more than 14wt% of the hydrophilic modifier prepared from the two-component silicone rubber raw material and mix well, vacuum degas for 10 min, then send it into the injection molding equipment, injection molded at 20±0.5MPa, then vulcanized at 155℃ for 80 s, and sterilized after demolding to obtain medical catheter material.

[0041] Example 3: Preparation of medical catheter materials, the specific implementation method is as follows:

[0042] I. Preparation of hydrophilic modifiers

[0043] Step A1: Take single-ended hydrogen-containing silicone oil (raw material information: RH-H222-3, room temperature viscosity 100 mm). 2 / s, with a silane content of 0.03wt%) and allyl epoxy polyoxyethylene polyether (raw material information: PR-601, average molecular weight 450) were added according to the equimolar ratio of silane content and allyl content. Toluene was added at 0.85 times the total weight of the two and stirred until well mixed. Nitrogen gas was introduced for protection and the temperature was raised to 100°C. Karstedt catalyst (raw material platinum content of 5000ppm) was slowly added at a platinum concentration of 35ppm in the raw material and stirred for 4.2h. After the reaction was completed, toluene was removed by rotary evaporation under reduced pressure to obtain the epoxy intermediate.

[0044] Step A2: Take epoxy intermediate and divinyl ethylene glycol, with the epoxy content of epoxy intermediate and the molar ratio of divinyl ethylene glycol being 1:0.55. Add 1.5 times the weight of dioxane to both and stir to mix well. Then, add 0.9 wt% of tetrabutylammonium bromide as raw material and mix. Heat to 70°C and stir to react for 10 hours. After the reaction is completed, remove dioxane by rotary evaporation under reduced pressure to obtain the hydrophilic modifier.

[0045] II. Preparation of Medical Catheter Materials

[0046] Take two-component silicone rubber raw material (raw material information: HY-921), mix its A component and B component at a weight ratio of 1:1.5, add more than 18wt% of the hydrophilic modifier prepared from the two-component silicone rubber raw material and mix well, vacuum degas for 10 minutes, then send it into the injection molding equipment, injection molded at 20±0.5MPa, then vulcanized at 165℃ for 85s, and sterilized after demolding to obtain medical catheter material.

[0047] Example 4: Preparation of medical catheter materials, the specific implementation method is as follows:

[0048] I. Preparation of hydrophilic modifiers

[0049] Step A1: Take single-ended hydrogen-containing silicone oil (raw material information: RH-H222-3, room temperature viscosity 100 mm). 2 / s, with a silane content of 0.03wt%) and allyl epoxy polyoxyethylene polyether (raw material information: PR-601, average molecular weight 450) were added according to the equimolar ratio of silane content and allyl content. Toluene was added at 0.8 times the total weight of the two and stirred until well mixed. Nitrogen gas was introduced for protection and the temperature was raised to 95°C. Karstedt catalyst (raw material platinum content of 5000ppm) was slowly added at a platinum concentration of 40ppm in the raw material and stirred for 4.5h. After the reaction was completed, toluene was removed by rotary evaporation under reduced pressure to obtain the epoxy intermediate.

[0050] Step A2: Take epoxy intermediate and divinyl ethylene glycol, with the epoxy content of epoxy intermediate and the molar ratio of divinyl ethylene glycol being 1:0.53. Add 1.4 times the weight of dioxane to both and stir to mix well. Then, add 0.8 wt% of tetrabutylammonium bromide to the raw materials and mix. Heat to 65°C and stir to react for 11 hours. After the reaction is completed, remove dioxane by rotary evaporation under reduced pressure to obtain the hydrophilic modifier.

[0051] II. Preparation of Medical Catheter Materials

[0052] Take two-component silicone rubber raw material (raw material information: HY-921), mix its A component and B component at a weight ratio of 1:1.4, add more than 16wt% of the hydrophilic modifier prepared from the two-component silicone rubber raw material and mix well, vacuum degas for 10 min, then send it into the injection molding equipment, injection molded at 20±0.5MPa, then vulcanized at 160℃ for 90 s, and sterilized after demolding to obtain medical catheter material.

[0053] In the comparative example, based on existing technology research, allyl double-terminated polyether co-sulfurization was used. The specific raw material information is KLF-X. The specific implementation method is the same as in Example 4, with the hydrophilic modifier replaced in equal amounts. The rest of the implementation method is exactly the same.

[0054] The above catheter samples were subjected to performance tests, specifically as follows: referring to ASTM D7334-08 standard, 1 μL of physiological saline was dropped onto the catheter surface using a contact angle meter, and the static contact angle was recorded; referring to ISO 10993-5-2023 standard, L929 mouse fibroblasts were used, and the relative cell proliferation rate (RGR) of the sample extract was tested by the MTT method.

[0055] Mechanical property tests were performed on the above-mentioned catheter samples, specifically as follows: referring to ASTM D412-16 standard, the catheters were cut into standard dumbbell-shaped test strips using a universal testing machine, and the tensile strength and elongation at break were tested; referring to ASTM D624-00 standard, the tear strength of right-angled specimens was tested using a universal testing machine; referring to ASTM D2990-17 standard, the creep of the samples was tested over 1000 hours under a constant stress of 0.5 MPa.

[0056] The catheter material prepared in the example has a contact angle of less than 60°, exhibiting good wettability and meeting the implantation requirements of conventional urinary catheters, short-distance drainage tubes, and other medical catheters. The relative cell proliferation reaches more than 80%, demonstrating reliable safety. In terms of mechanical properties, the catheter in the example has higher tensile strength, and its tear resistance and creep resistance are significantly better than those in the comparative example, exhibiting more reliable structural stability.

[0057] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A medical catheter material, characterized in that, It is made by co-curing two-component silicone rubber raw material and hydrophilic modifier; The hydrophilic modifier is prepared by the following method: Step A1: mix the single-end hydrogen-containing silicone oil, allyl epoxy polyoxyethylene polyether and toluene uniformly, heat to 90-100℃ under nitrogen protection, slowly add Karstedt catalyst and stir for 3.5-4.5h to prepare an epoxy intermediate, wherein the molar ratio of the silicon hydrogen group in the single-end hydrogen-containing silicone oil to the allyl group in the allyl epoxy polyoxyethylene polyether is 1:1, the room temperature viscosity of the single-end hydrogen-containing silicone oil is 50-100mm 2 / s, the average molecular weight of the allyl epoxy polyoxyethylene polyether is 400-500, and the platinum content of the Karstedt catalyst is 30-40ppm of both. Step A2: Mix the epoxy intermediate, divinyl glycol, and dioxane, add tetrabutylammonium bromide, heat to 55-70℃ and stir for 8-11 hours to prepare a hydrophilic modifier. The molar ratio of epoxy content in the epoxy intermediate to that in divinyl glycol is 1:0.52-0.55, and the tetrabutylammonium bromide content is 0.6-0.9 wt% of both. The hydrophilic modifier is 12-18 wt% of the two-component silicone rubber raw material.

2. The method for preparing a medical catheter material according to claim 1, characterized in that, Specifically, the process involves mixing two-component silicone rubber raw material and a hydrophilic modifier, followed by vacuum degassing, injection molding, vulcanization, demolding, and sterilization to obtain medical catheter material.

3. The method for preparing a medical catheter material according to claim 2, characterized in that, The vulcanization setting temperature is 155-165℃, and the time is 75-90s.