A high clarity tearable elastomeric material and tearable sheath and method of making same

Abstract

The application relates to the technical field of plastic modification, and particularly discloses a high-transparency tearable elastomer material and a tearable sheath tube and a preparation method thereof, the preparation method comprises the following steps: S1, uniformly mixing a main body resin and an auxiliary resin and drying to obtain a dry mixture; S2, feeding the dry mixture into a double-screw extruder for blending extrusion to obtain an extruded melt; S3, the extruded melt is filtered in a filtering device, and after filtering, the melt is extruded into a thin strip in a die head, and then the thin strip is cooled, solidified, dried and cut into particles to obtain the high-transparency tearable elastomer material; the viscosity of the main body resin is greater than that of the auxiliary resin; and the difference between the refractive indices of the main body resin and the auxiliary resin is not more than 0.1. The method adopts two or more than two kinds of thermoplastic materials with relatively close refractive indices and obvious viscosity differences for blending granulation, so that the product has both tearability and transparency, and the comprehensive requirements of clinical operation visualization and instrument performance are met.

Description

Technical Field

[0001] This invention relates to the field of plastic modification technology, and more specifically, to a high-transparency tearable elastomer material and a tearable sheath, and a method for preparing the same. Background Technology

[0002] Interventional therapy, as an important technical means in the field of modern medicine, uses minimally invasive methods to insert catheters and other instruments into the human body for diagnosis or treatment, and has been widely used in the fields of cardiovascular and oncology diseases. Its core instrument, the tearable catheter sheath, consists of a sheath, a dilator, and a guidewire, and is used to guide the instrument safely out of the blood vessel after it has entered the blood vessel. Especially in surgeries such as pacemaker implantation, the sheath must have tearable properties to achieve separation from the lead without any residue.

[0003] Traditional tear-resistant tubing is mostly made of plastic. However, ordinary plastic tubing, due to its uniform strength in both longitudinal and transverse directions, is difficult to tear in a controlled manner. Current technologies mainly improve tearability by unidirectional high-strength stretching or by adding incompatible additives to create stress-weak areas. However, stretching methods can lead to difficulties in controlling the dimensions of small-diameter tubing, and additive methods may affect the mechanical properties of the material. Furthermore, neither of these methods can simultaneously achieve both transparency and production efficiency.

[0004] Currently, tearable catheter sheaths are mostly made of polytetrafluoroethylene (PTFE), whose production requires a complex multi-stage sintering process. This process is lengthy and intermittent, leading to low efficiency. Furthermore, the semi-sintered nature of PTFE results in insufficient transparency of the finished product, failing to meet clinical requirements for visualization during operation. These shortcomings stem from the non-melting processing characteristics of PTFE and its inherent technological limitations; current technologies have not effectively resolved the contradiction between tearability, transparency, and production efficiency.

[0005] To address the aforementioned issues, there is an urgent need to develop a catheter sheath material and preparation method that combines high transparency and excellent tearability, breaking through the processing limitations of traditional PTFE materials, achieving efficient and continuous production of tearable tubing, while ensuring good product transparency, and providing safer and more precise instrument support for interventional surgery. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of at least one of the above-mentioned prior art, and provides a high-transparency tearable elastomer material and a tearable sheath and a method for preparing the same. It uses two or more thermoplastic materials with similar refractive indices and significantly different viscosities for blending and granulation, so that the product has both good tearability and good transparency.

[0007] The technical solution adopted by the present invention is to provide a high-transparency tearable elastomer material, characterized in that it includes a main resin and an auxiliary resin, wherein the difference in melt flow rate between the main resin and the auxiliary resin is 2.5~9.2 g / 10min; and the difference in refractive index between the main resin and the auxiliary resin does not exceed 0.1.

[0008] The above method uses two or more resins with similar refractive indices but different viscosities for co-extrusion granulation. Because different resins have a certain degree of compatibility, the auxiliary resin is well dispersed within the main resin under the strong shear force of the twin-screw extruder. However, due to viscosity differences, they are not completely compatible, resulting in the formation of a marine phase and separated island phases. These island phases, after being stretched through the extruder, form slender, stress-weak regions, resulting in good tear resistance and linear tearing. Furthermore, because the refractive indices of the two or more resins are similar, the interfacial reflection between them is not significant, thus resulting in high material transparency.

[0009] Furthermore, the main resin accounts for 75% to 95%.

[0010] Furthermore, the main resin is selected from one of thermoplastic polyurethane (TPU), polyether block polyamide (Pebax), and thermoplastic polyester elastomer (TPEE). The preferred main resin type maximizes the inherent properties of the material to balance elasticity and support. Thermoplastic polyurethane (TPU) possesses high resilience and flexural strength, ensuring that the material extends along a predetermined direction without breaking during tearing; polyether block polyamide (Pebax) exhibits outstanding flexibility, maintaining longitudinal strength stability; and thermoplastic polyester elastomer (TPEE), with its high strength and fatigue resistance, provides a structural support substrate for the sheath. A proportion of 75% to 95% ensures that the main resin dominates the material's mechanical framework, preventing a decrease in overall strength due to excessive auxiliary resin. This lays a stable foundation for the formation of a synergistic structure of "strong matrix + weak interface" in tearability, ensuring that tearing occurs only along the weak areas formed by the dispersion of auxiliary resin.

[0011] Furthermore, the auxiliary resin is selected from one or more of ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-methyl acrylate copolymer (EMA), and ethylene-methacrylic acid copolymer (EMMA). Regarding compatibility, the EVA molecular chain contains polar vinyl acetate (VA) groups, which interact to some extent with the polar groups (such as amide and ester groups) of Pebax and TPEE, thus exhibiting a certain degree of compatibility. The polarity of EAA and EMA makes them compatible with a variety of polymers. Viscosity differences show that both the main resin category and the auxiliary resin category have various types with a large viscosity range, requiring the selection of combinations with significant viscosity differences. Regarding refractive index, the refractive indices of TPU, EVA, EAA, and EMA are all within the range of 1.48-1.51, with small differences, which is beneficial for maintaining transparency.

[0012] Furthermore, the auxiliary resin is selected from one or more of thermoplastic polyester elastomers, polyether block polyamides, and thermoplastic polyurethanes, which are different from the main resin. Selecting auxiliary resins belonging to the same thermoplastic elastomer category but with different properties expands the range of material choices and allows for more flexible combinations. For example, when the main resin is TPU, the auxiliary resin can be Pebax with lower hardness or TPEE with different crystallinity, utilizing the performance gradient (such as differences in hardness and melting point) under the compatibility of similar materials to form a more uniform stress-weak area; simultaneously, selecting an auxiliary resin with a refractive index closer to that of the main resin, such as TPEE and TPU, both with a refractive index of approximately 1.5, ensures the transparency of the elastomer material.

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned high-transparency tearable elastomer material, comprising the following steps: S1. Mix the main resin and auxiliary resin evenly and dry them to obtain a dry mixture; S2. The dried mixture is fed into a twin-screw extruder for co-extrusion to obtain the extruded melt; S3. The extruded melt enters a filtration device for filtration, and after filtration, it enters a die head to be extruded into thin strips, cooled, solidified, dried, and pelletized to obtain a high-transparency tearable elastomer material.

[0014] Furthermore, the aspect ratio of the twin screw described in step S2 is 25–50. Optimizing the aspect ratio helps improve the shear mixing effect, promotes uniform resin dispersion, and ensures consistent material properties.

[0015] Furthermore, the filtration accuracy of the filtration device described in step S3 is 30–50 μm. Limiting the filtration accuracy range is beneficial for removing impurities from the melt and further improving transparency.

[0016] Another object of the present invention is to provide a tearable sheath made of the aforementioned high-transparency tearable elastomer material.

[0017] Another object of the present invention is to provide a method for preparing the tearable sheath, comprising the following steps: The above-mentioned high-transparency tearable elastomer material is dried, extruded into a melt by a single screw, filtered, then extruded through a die, cooled and solidified, the outer diameter and stretching are measured, and finally wound or cut to obtain the tearable sheath.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for preparing a high-transparency tearable elastomer material. The method involves designing and improving the material blending system, using two or more resins with similar refractive indices and certain viscosity differences for co-extrusion granulation. This results in a tearable material that combines excellent tearability with transparency, providing safer and more precise instrument support for interventional surgery and meeting the comprehensive clinical needs for both operative visualization and instrument performance. Furthermore, by combining this with an optimized melt extrusion process, the method overcomes the limitations of the intermittent production process of traditional PTFE materials, enabling efficient and continuous production of tearable sheath materials. This significantly reduces production costs and resolves the contradiction between tearability, transparency, and production efficiency in existing technologies. Attached Figure Description

[0019] Figure 1 This is a cross-sectional schematic diagram of the tearable sheath provided by the present invention. Figure 1 a is the cross-section. Figure 1 b is the longitudinal section.

[0020] Labeling explanation: Main resin 1, auxiliary resin 2. Detailed Implementation

[0021] The present invention will now be further illustrated with specific examples. The following embodiments are merely illustrative and do not constitute a limitation thereof. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0022] Unless otherwise specified, all reagents and consumables used in the following examples are commercially available. Unless otherwise specified, the experimental methods are standard experimental methods in the art.

[0023] The high-transparency tearable elastomer materials provided in the following embodiments are all produced by melt-granulation of a main resin and an auxiliary resin. The process is as follows: The main resin and auxiliary resin are uniformly mixed, and the mixed raw material is dried with dehumidified air at 65-110°C. The dried raw material is then fed into a twin-screw extruder for blending and extrusion, with a length-to-diameter ratio (L / D) of 25-50 for the twin screws. After extrusion by the twin screws, the melt enters a filtration device for filtration. This filtration device is switchable and equipped with a filter screen with a filtration accuracy of 30-50 μm. The filtered melt enters a die and is extruded into thin strips. The extruded melt strips are cooled in a water bath. After the strips have been cooled and solidified in the water bath, excess surface moisture is blown away by air before pelletizing to obtain the high-transparency tearable material.

[0024] The process for manufacturing tearable sheaths from the aforementioned highly transparent tearable material is as follows: The highly transparent tearable material is thoroughly dried, extruded via a single screw extruder, filtered, and then fed into a mold. The mold consists of an inner mold and an outer mold, and the gap between them determines the thickness of the product tube. After the melt is extruded through the mold, it is cooled and solidified in a water bath. Its outer diameter is then measured by a diameter gauge, followed by stretching at a certain speed using a stretching machine, and finally wound up by a winding machine or cut into tubes of a certain length by a cutting machine.

[0025] The cross-section of the finished tearable sheath is as follows: Figure 1 As shown, Figure 1 a is a schematic diagram of the cross-section. Figure 1 b is a schematic diagram of the longitudinal section. Since the main resin 1 and auxiliary resin 2 are not completely compatible, they form a two-phase region after mixing. The majority of the main resin 1 forms a continuous marine phase, while the minority of the auxiliary resin 2 forms separated island phases. During pipe extrusion, the melt flows within the mold, and the pipe production process involves stretching. The auxiliary resin 2 (island phase) is stretched into thin strips along the pipe's production direction (longitudinal). When the ratio and compatibility of the two phases are appropriate, the number and size of these thin strips are suitable. When external force is applied to the pipe to tear it, the tear lines extend along the two-phase interface at the thin strips, resulting in a better tearing effect.

[0026] The main resin and auxiliary resin combinations selected in the following embodiments have relatively similar temperature resistance properties, so their processing temperature can simultaneously meet the processing requirements of both, ensuring processing stability.

[0027] Example 1 This embodiment provides a highly transparent tearable elastomer material, which is formed by melt granulation of a main resin and an auxiliary resin. The main resin is Pebax 3533 nylon elastomer, accounting for 88% by weight; the auxiliary resin is Surlyn 8940 resin, accounting for 12% by weight. The two are blended and dried at 85°C for 4 hours, and then processed by a twin-screw extruder with the following temperatures: zone 1 155°C, zone 2 160°C, zone 3 165°C, zone 4 165°C, zone 5 165°C, die head 155°C, screw speed 60 rpm, and feed rate 3.5 Hz.

[0028] Regarding viscosity differences, Pebax 3533 has a melt flow rate (MFR) of 12 g / 10 min; Surlyn 8940 is a derivative of EMMA with an MFR of 2.8 g / 10 min, which is significantly lower than the former. This means that the viscosity of Surlyn 8940 is significantly greater than that of Pebax 3533. When the melt is mixed, it is easy to form separated island phases, which form slender strips after extrusion and stretching, which is conducive to the formation of stress-weak areas.

[0029] Example 2 This embodiment provides a highly transparent tearable elastomer material, which is formed by melt granulation of a main resin and an auxiliary resin. The main resin is Pebax 3533 nylon elastomer, accounting for 95% by weight; the auxiliary resin is Surlyn 8940 resin, accounting for 5% by weight. The two are blended and dried at 85°C for 4 hours, and then processed by a twin-screw extruder with the following temperatures: zone 1 155°C, zone 2 160°C, zone 3 165°C, zone 4 165°C, zone 5 165°C, die head 155°C, screw speed 60 rpm, and feed rate 3.5 Hz.

[0030] Example 3 This embodiment provides a highly transparent tearable elastomer material, which is formed by melt granulation of a main resin and an auxiliary resin. The main resin is Pebax 3533 nylon elastomer, accounting for 75% by weight; the auxiliary resin is Surlyn 8940 resin, accounting for 25% by weight. The two are blended and dried at 85°C for 4 hours, and then processed by a twin-screw extruder with the following settings: zone 1 155°C, zone 2 160°C, zone 3 165°C, zone 4 165°C, zone 5 165°C, die head 155°C, screw speed 60 rpm, and feed rate 3.5 Hz.

[0031] Example 4 This embodiment provides a highly transparent tearable elastomer material, which is formed by melt granulation of a main resin and an auxiliary resin. The main resin is thermoplastic polyester elastomer (TPEE) Hytel 3078, accounting for 80% by weight; the auxiliary resin is DuPont EVA 460, accounting for 20% by weight. The two are blended and dried at 65°C for 4 hours, and then processed by a twin-screw extruder with the following settings: zone 1 180°, zone 2 185°, zone 3 190°, zone 4 190°, zone 5 195°, die head 185°, screw speed 40 rpm, and feed rate 2.5 Hz.

[0032] Regarding viscosity differences, Hytel 3078 has a melt flow rate (MFR) of 5.0 g / 10 min, while DuPont EVA 460 has a MFR of 2.5 g / 10 min, which is significantly lower than the former. This means that the viscosity of DuPont EVA 460 is significantly higher than that of Hytel 3078. During melt mixing, it is easy to form separated island phases, which form slender strips after extrusion and stretching, which is conducive to the formation of stress-weak areas.

[0033] Example 5 This embodiment provides a highly transparent tearable elastomer material, which is formed by melt granulation of a main resin and an auxiliary resin. The main resin is thermoplastic polyester elastomer (TPEE) Hytel 3078, accounting for 95% by weight; the auxiliary resin is DuPont EVA 460, accounting for 5% by weight. The two are blended and dried at 65°C for 4 hours, and then processed by a twin-screw extruder with the following settings: zone 1 180°, zone 2 185°, zone 3 190°, zone 4 190°, zone 5 195°, die head 185°, screw speed 40 rpm, and feed rate 2.5 Hz.

[0034] Example 6 This embodiment provides a highly transparent tearable elastomer material, which is formed by melt granulation of a main resin and an auxiliary resin. The main resin is thermoplastic polyester elastomer (TPEE) Hytel 3078, accounting for 75% by weight; the auxiliary resin is DuPont EVA 460, accounting for 25% by weight. The two are blended and dried at 65°C for 4 hours, and then processed by a twin-screw extruder with the following settings: zone 1 180°, zone 2 185°, zone 3 190°, zone 4 190°, zone 5 195°, die head 185°, screw speed 40 rpm, and feed rate 2.5 Hz.

[0035] Example 7 This embodiment provides a highly transparent tearable elastomer material, which is formed by melt granulation of a main resin and an auxiliary resin. The main resin is thermoplastic polyurethane (TPU) 2363-AE, accounting for 85% by weight; the auxiliary resins are Surlyn 8940, accounting for 10% by weight, and DuPont EVA460, accounting for 5% by weight. The two are blended and dried at 65°C for 4 hours, and then processed by a twin-screw extruder with the following settings: zone 1 185°C, zone 2 195°C, zone 3 200°C, zone 4 205°C, zone 5 205°C, die 202, screw speed 80 rpm, and feed rate 5.1 Hz.

[0036] Regarding viscosity differences, the melt flow rate (MFR) of thermoplastic polyurethane (TPU) 2363-AE is 10 g / 10 min; Surlyn 8940, a derivative of EMMA, has an MFR of 2.8 g / 10 min; and DuPont EVA 460 has an MFR of 2.5 g / 10 min. The MFRs of the two auxiliary resins are significantly lower than those of the host resin, meaning their viscosities are significantly higher. This facilitates the formation of separated island phases during melt mixing, which, after extrusion and stretching, form slender strips, thus contributing to the formation of stress-weak areas.

[0037] Example 8 This embodiment provides a highly transparent tearable elastomer material, which is formed by melt granulation of a main resin and an auxiliary resin. The main resin is thermoplastic polyurethane (TPU) 2363-AE, accounting for 75% by weight; the auxiliary resins are Surlyn 8940, accounting for 15% by weight, and DuPont EVA460, accounting for 10% by weight. The two are blended and dried at 65°C for 4 hours, and then processed by a twin-screw extruder with the following settings: zone 1 185°C, zone 2 195°C, zone 3 200°C, zone 4 205°C, zone 5 205°C, die 202, screw speed 80 rpm, and feed rate 5.1 Hz.

[0038] Using the highly transparent tearable elastomer materials obtained in Examples 1-8 as raw materials, tearable sheaths were prepared according to the above process, and performance tests were conducted. The tear force test method is as follows: the two ends of the joint were fixed with upper and lower clamps of a tensile testing machine, and a tensile test was performed according to the method specified in GB / T 1040-79. The maximum force at which the joint broke was recorded. The results are shown in the table below: Table 1

[0039] According to the results in Table 1, the tearable sheaths made from the highly transparent tearable elastomer materials provided in Examples 1-8 produce no or only a small amount of fuzz during the tearing process, the tearing force does not exceed 12 N, and the transparency is guaranteed. The products have both good tearability and transparency.

[0040] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific implementation of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. A high-transparency tearable elastomer material, characterized in that, It includes a main resin and an auxiliary resin, wherein the difference in melt flow rate between the main resin and the auxiliary resin is 2.5~9.2 g / 10min; and the difference in refractive index between the main resin and the auxiliary resin does not exceed 0.

1.

2. The high-transparency tearable elastomer material according to claim 1, characterized in that, The main resin accounts for 75% to 95%.

3. The high-transparency tearable elastomer material according to claim 1, characterized in that, The main resin is selected from one of thermoplastic polyurethane, polyether block polyamide, and thermoplastic polyester elastomer.

4. The high-transparency tearable elastomer material according to claim 1, characterized in that, The auxiliary resin is selected from one or more of ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer, and ethylene-methacrylic acid copolymer.

5. The preparation method according to claim 1, characterized in that, The auxiliary resin is selected from one or more of the following: thermoplastic polyester elastomer, polyether block polyamide, and thermoplastic polyurethane, which are different from the main resin.

6. A method for preparing a high-transparency tearable elastomer material according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Mix the main resin and auxiliary resin evenly and dry them to obtain a dry mixture; S2. The dried mixture is fed into a twin-screw extruder for co-extrusion to obtain the extruded melt; S3. The extruded melt enters a filtration device for filtration, and after filtration, it enters a die head to be extruded into thin strips, cooled, solidified, dried, and pelletized to obtain a high-transparency tearable elastomer material.

7. The preparation method according to claim 6, characterized in that, The length-to-diameter ratio of the twin screw in step S2 is 25 to 50.

8. The preparation method according to claim 6, characterized in that, The filtration accuracy of the filtration device described in step S3 is 30-50 μm.

9. A tearable sheath, characterized in that, Made using the high-transparency tearable elastomer material as described in any one of claims 1 to 5.

10. A method for preparing a tearable sheath according to claim 9, characterized in that, Includes the following steps: Take the high-transparency tearable elastomer material as described in any one of claims 1 to 5, dry it, extrude it into a melt using a single screw, filter it, then extrude it through a die, cool and solidify it, measure its outer diameter and stretching, and finally wind or cut it to obtain the tearable sheath.

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