Nerve stimulation needle containing insulating coating and preparation process thereof

Abstract

The invention belongs to the technical field of implantation medical instruments, and particularly relates to a nerve stimulation needle containing an insulating coating and a preparation process of the nerve stimulation needle. The nerve stimulation needle comprises a needle base, a metal needle tube with the tail end installed in the needle base, a medicine injection pipeline, a wire and a connector, the outer surface, away from the needle point of the metal needle tube smaller than or equal to 350 micrometers, of the metal needle tube located outside the needle base is coated with an insulating coating with the thickness of 25-60 micrometers, point discharge can be conducted only at the needle point, the positioning accuracy is high, the insulation voltage can reach 1 KV, and the service life of the nerve stimulation needle is prolonged. The operation of clinicians is convenient. The preparation process provided by the invention comprises the following steps: immersing a metal needle tube into an insulating coating liquid, taking out the metal needle tube, and carrying out thermocuring to form the insulating coating. And assembling the metal needle tube containing the coating into the needle seat, and connecting the medicine injection pipeline, the lead and the joint to form a product. And the dip-coating method is adopted, batch and large-scale production can be achieved, and compared with a common spraying process needing specific equipment, operation is easy, and the production cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of implantable medical devices, and in particular relates to a nerve stimulation needle containing an insulating coating and a preparation process thereof. Background Art

[0002] Nerve block is the process of injecting local anesthetic around nerve trunks, plexuses, and ganglia to block impulse conduction and produce anesthesia in the area controlled. The nerve stimulation needle is used in conjunction with a nerve stimulator. The tip of the nerve stimulation needle releases an electric current of a certain intensity and frequency to induce a motor response of the nerve-controlled muscle group, thereby locating the peripheral nerve that needs to be blocked. For peripheral nerve blocks, such as brachial plexus block and lumbar plexus block, the nerve stimulation needle needs the help of a nerve stimulator to help with correct, objective and precise positioning. The probability of the nerve stimulation needle directly contacting the nerve is extremely low. This requires the nerve stimulation needle to have good tube insulation and needle tip discharge function.

[0003] One method of insulating the needle tube is to use an insulating coating on the outer surface of the metal needle tube to achieve the insulation of the tube body. For example, Chinese patent application CN103127607A discloses a production process for a peripheral nerve stimulation needle, and the steps are as follows: polytetrafluoroethylene is coated on the surface of the injection needle tube with a metal needle seat to form an insulating layer, and 5-10mm of the root of the needle tube is retained without insulation treatment; the wire is connected to the root of the needle tube without the insulating layer; the needle seat jacket is injection molded, and then the needle seat jacket is put on the injection needle; glue is injected between the needle seat jacket and the metal needle seat; the injection needle tube with the insulating layer and the needle seat jacket are cleaned; after the treatment, the peripheral nerve stimulation needle is packaged and sterilized. The application does not disclose the preparation method and coating method of the coating, nor does it explain the firmness of the coating and the length of the exposed needle tip.

[0004] At present, when insulating nerve blocking needles, problems such as a large exposed distance of the needle tip and no insulating coating on the bevel of the needle tip blade often occur. At the same time, there are large differences in coating thickness. Applying a lower current intensity cannot cause muscle twitching, so a high-intensity stimulation current is required. It is even impossible to distinguish whether the needle tip has passed through the nerve, resulting in inaccurate positioning, easy damage to surrounding blood vessels and nerves, and a high risk of anesthesia. Therefore, how to develop a nerve stimulation needle with an appropriate coating thickness, firm and not easy to fall off, a small exposed discharge area of ​​the needle tip, precise positioning, and can effectively reduce complications and reduce nerve damage is a problem that needs to be solved urgently. Summary of the invention

[0005] Based on this, the object of the present invention is to provide a nerve stimulation needle containing an insulating coating, which can induce muscle twitching by stimulating with a relatively small current and has high positioning accuracy.

[0006] The present invention also provides a preparation process for a nerve stimulation needle containing an insulating coating, which has simple operation, low production cost and is easy to mass produce.

[0007] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a nerve stimulation needle with an insulating coating, comprising a needle seat 1, a metal needle tube 2 with its tail end installed in the needle seat, an injection pipeline 3, a wire 4 and a connector 5; the outer surface of the metal needle tube located outside the needle seat at a distance of ≤350μm from its needle tip is coated with an insulating coating 6 with a thickness of 25-60μm.

[0008] Furthermore, the insulating coating 6 is formed by first immersing the metal needle tube 2 into the insulating coating liquid, taking it out, and then thermally curing it.

[0009] Furthermore, the insulating coating liquid is prepared by using polyol resin as a main raw material, adding a curing agent, a rheological additive, a diluent, a wetting agent, a leveling agent, a silane coupling agent and a color paste, and mixing at room temperature.

[0010] Furthermore, the raw material components in the insulating coating liquid include: 65-80 parts of polyol resin, 6-8 parts of curing agent, 0.35-0.45 parts of rheological additive, 25-35 parts of diluent, 0.6-1 parts of wetting agent, 0.5-2 parts of leveling agent, 0.1-0.5 parts of silane coupling agent, and 1-3 parts of color paste; the raw material components are measured in parts by weight.

[0011] Furthermore, the polyol resin includes aliphatic-aromatic resin, which is prepared from polycarboxylic acid, anhydride and polyol as raw materials, under nitrogen protection, first reacting at 120-150° C. for 2-3 hours under the action of a catalyst, then heating to 170-230° C. and continuing to react for 2±0.5 hours before vacuuming.

[0012] Furthermore, the polycarboxylic acid includes adipic acid, the polyol includes hexylene glycol, the acid anhydride includes phthalic anhydride, and the catalyst includes zinc acetate; the raw material components include: 20-25 parts of adipic acid, 40-50 parts of hexylene glycol, 20-25 parts of phthalic anhydride, and 0.001-0.002 parts of zinc acetate; the raw material components are measured in parts by weight.

[0013] Furthermore, the curing agent includes an isocyanate-based resin, which is prepared by using 20-30 parts of hexamethylene diisocyanate and 32-66 parts of polyethylene glycol 800 as raw materials, adding 25-40 parts of an organic solvent, and heating at 60-100° C. for 2-4 hours under nitrogen protection; the organic solvent includes any one of xylene, toluene or butanone; the raw material components are measured in parts by weight.

[0014] Further, the rheological additive includes a modified urea solution (such as BYK-410 or BYK-411); the wetting agent includes a modified polyurethane solution (such as DISPERBYK-2163); the diluent includes any two of propylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, ethylene glycol methyl ether, propylene glycol methyl ether, and dipropylene glycol methyl ether; the silane coupling agent includes KH560 or Momentive A-187; the leveling agent includes polyether-modified polydimethylsiloxane (such as BYK-L9565), and the color paste includes an oily color paste (Chemours Ti-Pure™ R-902 + ).

[0015] The present invention also provides a process for preparing a nerve stimulation needle containing an insulating coating, comprising the following steps: S1, put the guide core 7 into the metal needle tube 2 with the outer surface roughened to seal the needle tip, immerse the blocked metal needle tube 2 vertically into the insulating coating liquid with the needle tip facing downward for 10-40 seconds, then take the metal needle tube 2 out of the insulating coating liquid and pull out the guide core; S2, heating and curing the metal needle tube 2 obtained in S1 at 60-100° C. for 4-8 hours; S3, assemble the metal needle tube 2 obtained in S2 into the needle seat 1, and connect the injection pipeline 3, the wire 4 and the connector 5.

[0016] Furthermore, the guide core 7 in S1 is a curved guide core with a diameter 10-20 μm smaller than the inner diameter of the metal needle tube 2, and its bending direction is consistent with the direction of the needle tip edge. The material includes any one of nylon, polypropylene or polyethylene; the metal needle tube 2 is pulled out at a speed of 3-5 mm / s.

[0017] The beneficial effects of the present invention are: 1. The exposed distance of the tip of the nerve stimulation needle with insulating coating in the present invention is ≤350μm, and point discharge can be performed only at the tip of the needle. A small current can cause muscle twitching, thereby improving the accuracy of positioning the nerve stimulation needle. The coating thickness is small, ranging from 25-60μm, and the insulation voltage can reach 1KV, which is convenient for clinicians to operate.

[0018] 2. The insulating coating liquid of the present invention uses polyol resin as the main raw material of aliphatic-aromatic resin, and the prepared product has good flexibility, and the coating is not easy to crack. There is no cracking in the limit test of 90° on the needle tube toughness tester. The coating has strong firmness.

[0019] 3. In the insulating coating liquid of the present invention, modified urea solution is used as a rheological additive, and the addition amount is controlled at 0.35-0.45 parts. The needle tip and the edge coating are controlled by rheological properties, so that the edge is easy to be coated with an insulating layer; when the coating is formed by thermal curing, the exposed distance of the needle tip can be ≤350μm through self-shrinkage.

[0020] 4. The insulating coating liquid of the present invention uses a two-component polyurethane raw material, and the toughness and hardness of the coating are controlled by the reaction of the polyol resin and the curing agent. The polyol is an aromatic-aliphatic polyol, which has good hardness and toughness. With the aliphatic curing agent, the coating has good toughness and hardness after curing. At the same time, the biological safety of the nerve stimulation needle is improved.

[0021] 5. The preparation process of the nerve stimulation needle containing the insulating coating in the present invention adopts a dipping method, which can realize batch and large-scale production. Compared with the common spraying process that requires specific equipment, it is simple to operate and has low production cost.

[0022] 6. The preparation process of the nerve stimulation needle containing an insulating coating in the present invention is to place a polymer curved guide core 10-20 μm smaller than the inner diameter of the metal needle tube for sealing. The bending direction of the guide core is consistent with the direction of the needle tip edge, which can ensure that the exposed part of the needle tip edge of the needle tube has an insulating coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Attached Figure 1 Schematic diagram of the structure of a nerve stimulation needle with an insulating coating, in which 1 is a needle seat, 2 is a metal needle tube, 3 is a drug injection pipeline, 4 is a wire, 5 is a connector, and 6 is an insulating coating; Attached Figure 2 The appearance diagrams of the metal needle tube sample of the nerve stimulation needle with the insulating coating in four directions according to the embodiment of the present invention are shown; Attached Figure 3 It is a schematic diagram of the plugging of the guide core in the present invention, in which 7 is the guide core; Attached Figure 4 This is an appearance diagram of a nerve stimulation needle with an insulating coating in an embodiment of the present invention, with 30 μm of the tip exposed; Attached Figure 5 This is an appearance diagram of a nerve stimulation needle with an insulating coating in an embodiment of the present invention, with 146 μm of the tip exposed; Attached Figure 6This is a test diagram of the puncture performance of the product prepared in an embodiment of the present invention on a bionic tissue; Attached Figure 7 This is a test diagram of the puncture performance of the product prepared in an embodiment of the present invention on pork with skin; Attached Figure 8 This is a test diagram of the bending performance of the product prepared in the embodiment of the present invention; Attached Fig. 9 This is a comparison chart of friction performance test between the product prepared in the embodiment of the present invention and the uncoated product; Attached Fig.10 This is an appearance picture of the product prepared in the comparative example of the present invention with the surface coating peeling off; Attached Fig.11 This is an appearance diagram of a product with uneven coating thickness prepared in a comparative example of the present invention; Attached Fig.12 This is a picture showing the uneven coating and exposed appearance of the needle tip edge of the product prepared in the comparative example of the present invention; Attached Fig.13 This is an appearance diagram of cracked coating of a product prepared in a comparative example of the present invention; Attached Fig.14 This is an appearance diagram of a product prepared in a comparative example of the present invention without coating on the cutting edge; Attached Fig.15 This is a product appearance picture of a needle tip prepared in a comparative example of the present invention, which is completely covered with a coating; Attached Fig.16 A summary table of raw material composition and process conditions for preparing polyol resins; Attached Fig.17 A summary table of raw material composition and process conditions for preparing curing agent; Attached Fig.18 The raw material composition and process conditions for synthesizing the insulating coating liquid are summarized in Table 1; Attached Fig.19 Table 2 is a summary of the raw material composition and process conditions for synthesizing the insulating coating liquid; Attached Fig. 20 A summary table of process conditions for preparing nerve stimulation needles with insulating coatings. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. The embodiments mentioned are all implemented on the premise of the technical solutions of the present invention, and detailed implementation processes are given, but it should be stated that the protection scope of the present invention is not limited to the following embodiments.

[0026] Examples 1-9 1. Preparation of Insulation Coating Liquid 1. Preparation of polyol resin: Add phthalic anhydride, adipic acid, hexylene glycol and zinc acetate in a reaction vessel in proportion, stir evenly, set the temperature to 120-150°C under nitrogen protection, react for 2h-3h for esterification and polycondensation reaction, increase the reaction temperature to 170-230°C after the reaction, continue the reaction for 2 hours, and then evacuate to obtain polyester polyol resin.

[0027] 2. Preparation of curing agent: Add polyethylene glycol 800, hexamethylene diisocyanate and organic solvent in proportion to a reaction container, stir evenly, and heat at 60-100°C for 2-4h under nitrogen protection to obtain an active isocyanate resin.

[0028] 3. Synthetic insulating coating liquid: Add polyol resin, curing agent, rheological additive, diluent, wetting agent, leveling agent, silane coupling agent and color paste in proportion to a reaction container, and stir evenly at room temperature to obtain a synthetic insulating coating liquid.

[0029] 2. Preparation of Nerve Stimulation Needles with Insulating Coating S1, placing the insulating coating liquid in the liquid tank, placing the guide core 7 into the metal needle tube 2 whose outer surface has been roughened to seal the needle tip tube opening (refer to Figure 3 ), immerse the blocked metal needle tube 2 vertically into the insulating coating liquid with the needle tip facing downward for 10-40 seconds, then pull the metal needle tube 2 out of the insulating coating liquid at a speed of 3-5 mm / s, and pull out the guide core 7; the guide core 7 is a curved guide core with a diameter smaller than the inner diameter of the metal needle tube 2 by 10-20 μm, and its bending direction is consistent with the direction of the needle tip edge, and the material includes nylon, polypropylene or polyethylene; S2, heating and curing the metal needle tube 2 obtained in S1 at 60-100° C. for 4-8 hours; S3, assembling the metal needle tube 2 obtained in S2 into the needle seat 1, and connecting the injection pipeline 3, the wire 4 and the connector 5, so as to obtain the obtained nerve stimulation needle with insulating coating. Figure 1 shown.

[0030] Comparative Examples 1-9 The preparation steps of the insulating coating liquid and the nerve stimulation needle containing the insulating coating in Comparative Examples 1-9 are the same as those in the embodiment, except for the selection of raw materials and process parameters.

[0031] The raw material composition and process conditions in the embodiments and comparative examples are as follows: Figure 16-20 As shown, where: Attached Fig.16 A summary table of raw material composition and process conditions for preparing polyol resins; Attached Fig.17 A summary table of raw material composition and process conditions for preparing curing agent; Attached Fig.18The raw material composition and process conditions for synthesizing the insulating coating liquid are summarized in Table 1 (including polyol resin, curing agent, rheological additive and diluent); Attached Fig.19 Table 2 is a summary of the raw material composition and process conditions for synthesizing the insulating coating liquid (including wetting agent, leveling agent, silane coupling agent and color paste); Attached Fig. 20 A summary table of process conditions for preparing nerve stimulation needles with insulating coatings.

[0032] Effect characterization analysis The coating processes of the coated nerve stimulation needles prepared in the examples and comparative examples were observed respectively, and the relevant properties of the obtained nerve stimulation needles were tested.

[0033] The results show that the insulating coating liquids prepared in Comparative Examples 1-9 all had defects to varying degrees when applied to the nerve stimulation needles, such as Figure 10-15 In Comparative Example 1, the content of hexamethylene diisocyanate in the curing agent is too low, resulting in turbid coating, incomplete curing of the coating and easy falling off. Fig.10 As shown; in Comparative Example 2, a large amount of polyethylene glycol 800 was added during the preparation of the curing agent, which caused the curing agent to solidify, so it could not be used during the preparation of the coating liquid, resulting in the defect that the coating could not be cured; Comparative Example 3 was proposed at a fast speed, resulting in a thick coating on the needle tip and obvious protrusions, such as Fig.11 As shown; Comparative Example 4 proposed a slow speed, there appeared uneven tip edge, exposed defects, such as Fig.12 As shown; in Comparative Example 5, phthalic anhydride was not added during the preparation of the polyol resin, and the coating was soft and easy to fall off after puncture, as shown Fig.10 As shown; in Comparative Example 6, no adipic acid was added, and the needle bending coating cracked. Fig.13 As shown; in Comparative Example 7, no rheological additive was added, and there was a defect that there was no coating at the tip of the needle, and the edge was exposed, such as Fig.14 As shown; in Comparative Example 8, the amount of rheological additive added was too large, and the needle tip was completely covered by the coating, resulting in the problem of being unable to discharge during later use, such as Fig.15 As shown; when blocking in Example 9, the bending direction of the guide core is inconsistent with the cutting edge direction of the needle tip, resulting in the defect of no coating at the cutting edge, such as Fig.14 shown.

[0034] The insulating coating liquid prepared in Examples 1-9 can be applied to the nerve stimulation needle to obtain a completely cured and uniform coating (such as Figure 2 As shown), the outer surface of the metal needle tube outside the needle seat at a distance of ≤350μm from the needle tip is coated with an insulating coating with a thickness of 25-60μm (as shown Figure 4 and Figure 5). The nerve stimulation needle with insulating coating obtained in any embodiment was repeatedly punctured on simulated skin (i.e., bionic tissue) and pork with skin to test the firmness of the needle tip coating. The test results are as follows: Figure 6 and Figure 7 As shown in the figure, the coating on the needle tip was observed and compared before and after puncture under the image measuring instrument with a magnification of 100 times. After 50 times of bionic tissue puncture, the coated needle was slightly detached at the needle tip, and after 30 times of puncture of pork skin, it was slightly detached. It was not visible under direct observation. The 60° and 90° tests were carried out on the medical needle tube toughness tester, and the needle was bent 10 times. The test results are shown in the figure. Figure 8 As shown, the coating does not crack. According to the test method of "GB 15811-2016 Disposable Sterile Injection Needles", the needle tip puncture force is tested. The puncture force of the uncoated blank needle is 1.37N, and the puncture force of the coated nerve stimulation needle is 1.76N, which meets the requirements. According to "YY / T1536-2017 Standard Test Model for Evaluation of Surface Sliding Performance of Non-Intravascular Catheters", the friction coefficient of the nerve stimulation needle before and after coating is tested in dry state. The test results are shown in the figure below. Fig. 9 As shown, the friction coefficient of the tube body after coating is smaller than that of the tube body before coating, and the tube body after coating is more lubricated than the uncoated tube body.

[0035] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nerve stimulation needle with an insulating coating, comprising a needle seat, a metal needle tube with its tail end installed in the needle seat, a drug injection pipeline, a wire and a connector, characterized in that: An insulating coating with a thickness of 25-60 μm is coated on the outer surface of the metal needle tube located outside the needle seat at a distance of ≤350 μm from the needle tip.

2. The nerve stimulation needle with insulating coating according to claim 1, characterized in that: The insulating coating is formed by first immersing the metal needle tube into the insulating coating liquid, taking it out, and then subjecting it to thermal curing.

3. The nerve stimulation needle with insulating coating according to claim 2, characterized in that: The insulating coating liquid is prepared by mixing polyol resin as a main raw material, adding a curing agent, a rheological aid, a diluent, a wetting agent, a leveling agent, a silane coupling agent and a color paste, and mixing at room temperature.

4. The nerve stimulation needle with insulating coating according to claim 3, characterized in that: The raw material components in the insulating coating liquid include: 65-80 parts of polyol resin, 6-8 parts of curing agent, 0.35-0.45 parts of rheological additive, 25-35 parts of diluent, 0.6-1 parts of wetting agent, 0.5-2 parts of leveling agent, 0.1-0.5 parts of silane coupling agent, and 1-3 parts of color paste; the raw material components are calculated by weight.

5. The nerve stimulation needle with insulating coating according to claim 3, characterized in that: The polyol resin includes aliphatic-aromatic resin, which is prepared by using polycarboxylic acid, acid anhydride and polyol as raw materials, and first reacting at 120-150° C. for 2-3 hours under nitrogen protection and then heating to 170-230° C. to continue reacting for 2±0.5 hours before vacuuming.

6. The nerve stimulation needle with insulating coating according to claim 5, characterized in that: The polycarboxylic acid includes adipic acid, the polyol includes hexanediol, the acid anhydride includes phthalic anhydride, and the catalyst includes zinc acetate; the raw material components include: 20-25 parts of adipic acid, 40-50 parts of hexanediol, 20-25 parts of phthalic anhydride, and 0.001-0.002 parts of zinc acetate; the raw material components are measured in parts by weight.

7. The nerve stimulation needle with insulating coating according to claim 3, characterized in that: The curing agent comprises an isocyanate-based resin, which is prepared by using 20-30 parts of hexamethylene diisocyanate and 32-66 parts of polyethylene glycol 800 as raw materials, adding 25-40 parts of an organic solvent, and heating at 60-100° C. for 2-4 hours under nitrogen protection; the raw material components are measured in parts by weight.

8. The nerve stimulation needle with insulating coating according to claim 3, characterized in that: The rheological additive includes a modified urea solution, the wetting agent includes a modified polyurethane solution, and the diluent includes any two of propylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, ethylene glycol methyl ether, propylene glycol methyl ether, and dipropylene glycol methyl ether.

9. A process for preparing a nerve stimulation needle with an insulating coating according to any one of claims 1 to 8, characterized in that: The steps include: S1, a guide core is placed inside a metal needle tube with a roughened outer surface to seal the needle tip, and the sealed metal needle tube is vertically immersed in an insulating coating liquid with the needle tip facing downward for 10-40 seconds, and then the metal needle tube is pulled out of the insulating coating liquid and the guide core is pulled out; S2, heating and curing the metal needle tube obtained in S1 at 60-100° C. for 4-8 hours; S3, assemble the metal needle tube obtained in S2 into the needle seat, and connect the injection pipeline, wire and connector.

10. The preparation method according to claim 9, characterized in that: The guide core in S1 is a curved guide core with a diameter 10-20 μm smaller than the inner diameter of the metal needle tube, and its bending direction is consistent with the direction of the needle tip edge. The material includes any one of nylon, polypropylene or polyethylene; the metal needle tube is pulled out at a speed of 3-5 mm / s.

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