Preparation method of insulating coating on surface of electric acupuncture needle instrument

Abstract

The invention provides a preparation method of an insulating coating on the surface of an electric acupuncture needle instrument, and relates to the field of material processing and preparation, and the preparation method comprises the following steps: preparing mixed powder of modified polyolefin and titanium dioxide; performing surface electrostatic spraying on the acupuncture base material by using the modified polyolefin and titanium dioxide mixed powder; and carrying out thermocuring treatment on the coating subjected to high-voltage electrostatic surface spraying treatment. The coating prepared on the surface of the electric acupuncture needle is low in relative dielectric constant and good in insulativity; due to fine regulation and control of the components, a compact and uniform insulating coating with a smooth surface can be formed after curing. Due to the addition of titanium dioxide, the coating has high strength, and meanwhile, due to the addition of the binder, the coating is not easy to fall off and has good durability; due to the addition of the biocompatible material, the skin tissue is almost not irritated.

Description

Technical Field

[0001] This invention belongs to the field of materials processing and preparation, specifically relating to a method for preparing an insulating coating on the surface of electroacupuncture needles, aiming to improve the coating efficiency, insulation properties and biocompatibility of the surface coating. Background Technology

[0002] Traditional Chinese medicine (TCM) is a great treasure of the Chinese nation, and acupuncture is an important tool in TCM treatment. Currently, there are few improvements to modern TCM acupuncture needles, hindering their integration with modern medicine and resulting in a lag in the development of treatable diseases and their advantages. In recent years, acupuncture has shown certain advantages in treating chronic diseases such as rhinitis, urinary tract infections, and sciatica, but it still has limitations in terms of operational difficulty and therapeutic effects.

[0003] Traditional Chinese medicine primarily relies on the physical contact of acupuncture needles with nerve ganglia and nerve trunks to stimulate them and achieve therapeutic effects. However, human nerve ganglia and nerve trunks are located deep within the body, and the irregular shape of the sutures makes it difficult to ensure effective stimulation of the target structures during acupuncture. Furthermore, these ganglion sites often have accompanying blood vessels; puncturing these vessels during acupuncture can cause adverse reactions such as deep tissue edema. To effectively address these drawbacks, modern Chinese medicine combines traditional acupuncture with modern electrostimulation therapy. An electric current is introduced into the tip of the acupuncture needle, thereby stimulating the nerve ganglia and nerve trunks through discharge at a distance from the needle tip, achieving the therapeutic effects of traditional acupuncture.

[0004] However, this method still has room for improvement. Because traditional acupuncture needles are electrically conductive, and the human body is also a conductor, as the current flows through the needle to the needle tip, this current diffuses through the needle surface into the body tissue, stimulating other nerves within the tissue and causing a poor patient experience during treatment. Furthermore, current loss also weakens the current intensity at the needle tip, significantly reducing the therapeutic effect. Therefore, it is essential to improve traditional needles so that they can better complement electrical stimulation therapy to achieve the best therapeutic results.

[0005] From the perspective of insulation principles, an insulating coating can be added to the surface of traditional acupuncture needles to fundamentally avoid the aforementioned problems. However, there is currently a lack of such products on the market, and acupuncture needles required for electroacupuncture therapy need a surface coating with high insulation, low peeling rate, and high biocompatibility to achieve the therapeutic effect of electroacupuncture. However, traditional surface coating processing and application methods have problems such as difficulty in controlling insulation, high peeling rate, and low biocompatibility and biosafety. Summary of the Invention

[0006] The purpose of this invention is to address the problems of poor coating effect, low insulation properties, and poor biocompatibility of existing electroacupuncture acupuncture needles. It provides a surface coating method based on phosphating treatment of the acupuncture needle surface combined with modified polyolefin synthetic resin and electrostatic powder spraying. Phosphating treatment forms a good underlayer on the needle surface, further improving the adhesion of the subsequent insulating coating and thus enhancing the coating's durability. The introduction of a low relative permittivity polyolefin synthetic resin and control of the coating thickness improve the insulation properties of the surface coating. The high-voltage electrostatic powder spraying method solves the problem of fine control over the coating thickness and electromagnetic properties.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] This invention provides a method for preparing an insulating coating on the surface of electroacupuncture needles, comprising the following steps:

[0009] S1. Prepare a mixed powder of modified polyolefin and titanium dioxide; wherein the modified polyolefin, due to its good ductility, can ensure the smoothness of the final surface coating and also has an insulating effect. Titanium dioxide has a certain hardness, and its presence in the insulating coating material can improve the wear resistance of the insulating coating and enhance the durability of the needle during use.

[0010] S2. The modified polyolefin and titanium dioxide mixed powder is used to perform electrostatic spraying on the surface of the acupuncture substrate; the present invention helps to form a uniform coating on the surface of the needle through electrostatic spraying technology, avoiding the phenomenon of excessive local thickness.

[0011] S3. The coating treated with high-voltage electrostatic spraying is then subjected to thermal curing. This invention melts the binder in the powder components through heating, forming a network structure. This connects other powder particles into a whole, ensuring the coating has good mechanical strength and adhesion. Furthermore, because the powder particles used in electrostatic spraying are smaller, the coating surface is smoother and more even after curing, and the gloss is generally superior to that obtained using traditional spraying methods.

[0012] Optionally, step S1 includes the following steps:

[0013] S11. Mix the dry polyolefin powder with the swelling agent to swell the polyolefin powder;

[0014] S12. Add titanium dioxide to the liquid obtained in step S11 and stir to form a homogeneous suspension.

[0015] S13. Add antioxidants, biocompatible materials and binders to the suspension obtained in step S12, and heat and stir the resulting mixture under water bath conditions.

[0016] S14. After cooling the mixture obtained in S13, dry it under reduced pressure to obtain the modified polyolefin and titanium dioxide mixed powder.

[0017] Optionally, in step S11, the polyolefin is at least one of polypropylene and hydrogenated styrene-butadiene-styrene copolymer, with a polymer molecular weight of 1,000 to 100,000. This invention is also applicable to other similar materials, such as polyethylene, polystyrene, and polybutadiene.

[0018] Optionally, in step S11, the swelling agent is at least one of xylene or cyclohexane.

[0019] Optionally, in step S11, the dried polyolefin powder and the swelling agent are contacted in a three-necked flask for 20 to 40 minutes, and the mass-volume ratio of the polyolefin powder to the swelling agent is 1 g: 8 ml.

[0020] Optionally, in step S12, the mass ratio of polyolefin powder to titanium dioxide is 1:(0.06~0.12). If the amount of titanium dioxide added is too low, the strength of the final coating will decrease; if the amount of titanium dioxide added is too high, the coating will become too strong and brittle, and will easily fall off during use.

[0021] Optionally, in step S13, the biocompatible material is at least one of esterified polyhydroxyacetic acid, polylactic acid, polycaprolactone, polysuccinate, polyβ-hydroxybutyrate, or polyurethane.

[0022] The adhesive is at least one of succinimide succinate or citrate-esterified polyvinyl alcohol;

[0023] The antioxidant is Irganox 1076.

[0024] Optionally, in step S13, the mass ratio of the four substances—polyolefin powder, antioxidant, biocompatible material, and binder—is 1:(0.03~0.06):(0.01~0.06):(0.01~0.06). For the antioxidant, if the amount added is too small, the coating will become brittle and more prone to peeling; if the amount added is too large, the antioxidant will precipitate on the coating surface, thus affecting the smoothness of the coating surface. For the biocompatible material, if the amount added is too small, after curing, a large amount of polyolefin will encapsulate the added biocompatible material inside the polyolefin material, thus losing its function; if the amount added is too large, it will increase the viscosity of the powder on the needle surface in the molten state during the curing process, hindering the flow of polyolefin and thus destroying the density of the coating surface. If too little adhesive is added, there will be more pores in the microstructure of the coating, which will affect the overall insulation performance and reduce the strength of the coating. If too much adhesive is added, the coating will shrink more during the subsequent high-temperature curing process, which will cause stress in the coating and make the coating surface prone to cracking.

[0025] Optionally, in step S13, the water bath heating temperature is 60~80°C, the heating time is 600~800 minutes, and stirring is performed continuously during the process.

[0026] Optionally, in step S14, the drying temperature is 70~90°C and the drying time is 15~30 h.

[0027] Optionally, after obtaining the modified polyolefin and titanium dioxide mixed powder in steps S1 and S14, it is ball-milled to achieve size control. The ball-milling parameters include: a ball milling zirconium bead to powder volume ratio of 1:1, a ball mill speed of 200~600 r / min, and a ball milling time of 8~24 h.

[0028] Optionally, before electrostatic spraying, the surface of the acupuncture substrate undergoes a cleaning pretreatment and a phosphating treatment. Further, the acupuncture substrate is made of 304 stainless steel. The cleaning pretreatment can be achieved through degreasing, washing, pickling, neutralization, and drying steps. The phosphating treatment involves immersing the pretreated acupuncture substrate in a phosphating solution for 30 minutes to 1 hour, then removing it and washing away any residual phosphating solution from the surface, thus completing the phosphating treatment. The purpose of the phosphating treatment is to form a phosphate underlayer on the surface of the acupuncture substrate, thereby increasing the adhesion of the insulating coating.

[0029] Optionally, in step S2, the acupuncture substrate that has undergone surface pretreatment and phosphating is electrostatically sprayed with a mixture of ball-milled modified polyolefin and titanium dioxide powder. Further, the powder spraying rate is 100~300 g / min, the voltage of the high-voltage electrostatic generator is 40~120 kV, and the current is limited to 16µA to prevent rapid charge saturation on the needle surface; the working distance between the sprayed sample and the spray gun is 300 mm.

[0030] Optionally, in step S3, the coating treated with high-voltage electrostatic spraying is subjected to thermal curing. Further, a drying oven with a uniform temperature field distribution is used for thermal curing. The temperature at any point within the working area must deviate from the reference point by no more than ±3℃ within a given time. The curing temperature is 150~350℃, and the curing time is 20~60 min.

[0031] The present invention also provides an insulating coating on the surface of an electroacupuncture needle prepared by the method, wherein the coating has a thickness of 3 to 5 µm and a relative permittivity of 2.6 to 3.1.

[0032] The method provided by this invention can prepare a coating with high insulation properties, high strength, and controllable coating thickness on the surface of electroacupuncture needles, and has the following advantages:

[0033] 1. The coating prepared on the surface of electroacupuncture needles by this invention has a low relative permittivity and good insulation properties. Due to the precise control of the components, a dense, uniform, and smooth insulating coating can be formed after curing. Furthermore, the addition of titanium dioxide results in high coating strength, while the addition of a binder makes the coating less prone to peeling off and provides good durability.

[0034] 2. The modified polyolefin component used in the raw materials of this invention has ductility, so the coating thickness can be precisely controlled by adjusting the amount of powder sprayed.

[0035] 3. The coating of the electroacupuncture needles prepared by the present invention has good surface biocompatibility due to the addition of biocompatible materials, and is almost non-irritating to skin tissue. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a scanned image of the surface morphology of the insulating coating on the surface of the acupuncture needles in Embodiment 1 of the present invention;

[0038] Figure 2 The results show the surface morphology and thickness measurement of the insulating coating on the surface of the acupuncture needles in Embodiment 1 of the present invention;

[0039] Figure 3 The results are the relative permittivity test results of the insulating coating on the surface of acupuncture needles in Examples 1-7 and Comparative Examples 1-2 of this invention;

[0040] Figure 4 The dielectric strength test results of the insulating coating on the surface of acupuncture needles in Examples 1-7 and Comparative Examples 1-2 of this invention;

[0041] Figure 5 The results of the arc resistance time test of the insulating coating on the surface of acupuncture needles in Examples 1-7 and Comparative Examples 1-2 of this invention;

[0042] Figure 6 The results are the peeling rate test results of the insulating coating on the surface of acupuncture needles in Examples 1-7 and Comparative Examples 1-2 of this invention. Detailed Implementation

[0043] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0044] In the following examples and comparative examples, the ovens were purchased from Shanghai Yiheng Scientific Instruments Co., Ltd., and the oven model was DHG-9240A.

[0045] Example 1

[0046] A method for preparing a surface coating for polypropylene-based electroacupuncture needles includes the following steps:

[0047] (1) Mix 10 g of dry polypropylene powder with a molecular weight of 50,000 with 80 mL of xylene in a three-necked flask for 30 minutes to allow the polypropylene powder to swell.

[0048] (2) Add 0.9 g of titanium dioxide to the solution obtained in step (1) and stir to form a homogeneous suspension;

[0049] (3) Add 0.03 g of anti-aging agent Irganox 1076, 0.03 g of polyurethane and 0.03 g of citric acid esterified polyvinyl alcohol to the above suspension;

[0050] (4) Place the mixture obtained in step (3) in a water bath and maintain the temperature at 70°C for 720 minutes, stirring continuously during the process;

[0051] (5) The cooled mixture from step (4) was dried under reduced pressure and then dried at 85°C for 24 h to obtain a powder sample;

[0052] (6) The powder sample obtained in step (5) is ball-milled. The volume ratio of zirconia beads to powder is 1:1. The ball mill speed is 300 r / min and the ball milling time is 12 h.

[0053] (7) The 304 stainless steel acupuncture substrate is subjected to surface cleaning pretreatment and phosphating treatment. The cleaning pretreatment is achieved by degreasing, washing with water, pickling, neutralization and drying. The phosphating treatment is to soak the pretreated acupuncture substrate in a phosphating solution (containing 30 g / L zinc dihydrogen phosphate and 60 g / L zinc nitrate) for 1 hour and then take it out.

[0054] (8) Using the ball milled powder obtained in step (6), electrostatic spraying is performed on the surface of the treated 304 stainless steel acupuncture substrate. The powder spraying rate is 150 g / min, the voltage of the high voltage electrostatic generator is 80 kV, and the current is 16 µA; the working distance between the sprayed sample and the spray gun is 300 mm.

[0055] (9) After spraying, cure at 250°C for 40 min. Finally, an insulating coating for acupuncture needles used for electroacupuncture is obtained on the surface of the stainless steel acupuncture substrate.

[0056] The relative permittivity (ε) of the coating was obtained by using the plate-parallel plate capacitance method. r The dielectric strength of the coating was 2.6; using the breakdown strength-short-time method for solid insulation materials, the dielectric strength of the coating was 36 kV / mm; using the ASTM D495 test method for high voltage and low current dry arc resistance of solid electrical insulation materials, the arc resistance time of the coating was 130 s; using the cross-cut adhesion test, the coating adhesion rate was less than 0.01%; according to GB / T 16886.5-2017 MTT containing 10% fetal bovine serum MEM extraction, in vitro cytotoxicity test showed no cytotoxicity; according to GB / T 16886.10-2017 Guinea pig maximum dose test 0.9% sodium chloride injection extraction, the skin sensitization test was negative; no irritating erythema was observed on the skin after 24 h.

[0057] Figure 1 This is a scanning image of the surface morphology of the insulating coating on the surface of the acupuncture needle in Embodiment 1 of the present invention, illustrating that the coating surface is smooth and flat. Figure 2 The results of surface morphology and thickness measurement of the insulating coating on the surface of the acupuncture needle in Embodiment 1 of the present invention show that the coating thickness on the surface of the acupuncture needle is in the range of 3~5µm and the coating thickness is uniform.

[0058] Example 2

[0059] A method for preparing a surface coating for polypropylene-based electroacupuncture acupuncture needles. The difference between this embodiment and Example 1 lies only in the amount of binder added; the specific changes are as follows:

[0060] The amount of citric acid esterified polyvinyl alcohol added in step (3) was changed to 0.01 g, and the remaining preparation steps and parameters remained the same as in Example 1.

[0061] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε). r The dielectric strength was 2.8; the arc resistance was 31 kV / mm; the arc resistance time was 127 s; the coating adhesion test showed a peeling rate of less than 0.03%; the in vitro cytotoxicity test showed no cytotoxicity; the skin sensitization test was negative; and no irritating erythema was observed on the skin after 24 hours.

[0062] Example 3

[0063] A method for preparing a surface coating for polypropylene-based electroacupuncture acupuncture needles. The difference between this embodiment and Example 1 lies only in the amount of binder added; the specific changes are as follows:

[0064] The amount of citric acid esterified polyvinyl alcohol added in step (3) was changed to 0.06 g, and the remaining preparation steps and parameters remained the same as in Example 1.

[0065] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε). r The dielectric strength was 2.7, the arc resistance was 33 kV / mm, the coating adhesion test showed a peeling rate of less than 0.02%, the in vitro cytotoxicity test showed no cytotoxicity, the skin sensitization test was negative, and no irritating erythema was observed on the skin after 24 hours.

[0066] Example 4

[0067] A method for preparing a surface coating for electroacupuncture needles based on hydrogenated styrene-butadiene-styrene copolymer. The difference between this embodiment and Example 1 lies in the use of a different polyolefin material, specifically as follows:

[0068] Replace 10 g of dried polypropylene powder with a molecular weight of 50,000 in step (1) with 10 g of dried hydrogenated styrene-butadiene-styrene copolymer powder with a molecular weight of 100,000, and replace 80 mL of xylene with 80 mL of cyclohexane. The remaining preparation steps and parameters are the same as in Example 1.

[0069] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε).r The dielectric strength was 2.9; the dielectric strength was 32 kV / mm; the arc resistance time was 128 s; the coating adhesion test showed a peeling rate of less than 0.02%; the in vitro cytotoxicity test showed no cytotoxicity; the skin sensitization test was negative; and no irritating erythema was observed on the skin after 24 hours.

[0070] Example 5

[0071] A method for preparing a surface coating for polypropylene-based electroacupuncture acupuncture needles. The difference between this embodiment and Example 1 lies in the type of adhesive used, specifically as follows:

[0072] In step (3), 0.03 g of citrate-esterified polyvinyl alcohol was replaced with 0.02 g of succinimide succinate, and the remaining preparation steps and parameters were the same as in Example 1.

[0073] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε). r The dielectric strength was 2.8; the dielectric strength was 34 kV / mm; the arc resistance time was 127 s; the coating adhesion test showed a peeling rate of less than 0.04%; the in vitro cytotoxicity test showed no cytotoxicity; the skin sensitization test was negative; and no irritating erythema was observed on the skin after 24 hours.

[0074] Example 6

[0075] A method for preparing a surface coating for polypropylene-based electroacupuncture acupuncture needles. This embodiment differs from Example 1 in that the process parameters are different, specifically as follows:

[0076] Change the amount of titanium dioxide added in step (2) to 0.6 g; reduce the temperature of the mixture in step (4) to 60°C and extend the holding time to 800 minutes; reduce the drying temperature in step (5) to 70°C and extend the drying time to 30 h; reduce the ball mill speed in step (6) to 200 r / min and extend the ball milling time to 24 h; increase the required powder spraying amount in step (8) to 300 g / min and reduce the voltage of the high-voltage electrostatic generator to 40 kV. Reduce the curing temperature in step (9) to 150°C and extend the curing time to 60 min.

[0077] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε). r The dielectric strength was 2.7; the dielectric strength was 32 kV / mm; the arc resistance time was 128 s; the coating adhesion test showed a peeling rate of less than 0.06%; the in vitro cytotoxicity test showed no cytotoxicity; the skin sensitization test was negative; and no irritating erythema was observed on the skin after 24 hours.

[0078] Example 7

[0079] A method for preparing a surface coating for polypropylene-based electroacupuncture acupuncture needles. This embodiment differs from Example 1 in that the process parameters are different, specifically as follows:

[0080] Change the amount of titanium dioxide added in step (2) to 1.2 g; increase the temperature of the mixture in step (4) to 80°C and shorten the holding time to 600 minutes; increase the drying temperature in step (5) to 90°C and shorten the drying time to 15 h; increase the ball mill speed in step (6) to 600 r / min and shorten the ball milling time to 8 h; reduce the required powder spraying amount in step (8) to 100 g / min and increase the voltage of the high-voltage electrostatic generator to 120 kV. Increase the curing temperature in step (9) to 350°C and shorten the curing time to 20 min.

[0081] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε). r The dielectric strength was 3.1; the arc resistance was 35 kV / mm; the arc resistance time was 123 s; the coating adhesion test showed a peeling rate of less than 0.05%; the in vitro cytotoxicity test showed no cytotoxicity; the skin sensitization test was negative; and no irritating erythema was observed on the skin after 24 hours.

[0082] Comparative Example 1

[0083] A method for preparing a surface coating for polypropylene-based electroacupuncture acupuncture needles. This comparative example differs from Example 1 only in that it does not contain a binder citric acid esterified polyvinyl alcohol; the remaining preparation steps and parameters are consistent with Example 1.

[0084] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε). r The dielectric strength was 29 kV / mm; the arc resistance time was 106 s; the coating adhesion test showed a peeling rate of less than 6%; the in vitro cytotoxicity test showed no cytotoxicity; the skin sensitization test was negative; and no irritating erythema was observed on the skin after 24 hours.

[0085] Comparative Example 2

[0086] A method for preparing a surface coating for polypropylene-based electroacupuncture acupuncture needles. This comparative example differs from Example 1 only in the process parameters of the curing step, specifically as follows:

[0087] The curing temperature in step (9) was reduced to 120°C and the curing time was shortened to 10 min. The remaining preparation steps and parameters were the same as in Example 1.

[0088] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε). r The dielectric strength was 27 kV / mm; the arc resistance time was 115 s; the coating adhesion test showed a peeling rate of less than 0.9%; the in vitro cytotoxicity test showed no cytotoxicity; the skin sensitization test was negative; and no irritating erythema was observed on the skin after 24 hours.

[0089] Comparative Example 3

[0090] A method for preparing a surface coating for polypropylene-based electroacupuncture acupuncture needles. This comparative example differs from Example 1 only in the amount of titanium dioxide added; the specific changes are as follows:

[0091] The amount of titanium dioxide added in step (2) was increased to 1.6 g, and the remaining preparation steps and parameters remained the same as in Example 1.

[0092] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε). r The dielectric strength was 2.9; the dielectric strength was 30 kV / mm; the arc resistance time was 113 s; the coating adhesion test showed a peeling rate of less than 2.3%; the in vitro cytotoxicity test showed no cytotoxicity; the skin sensitization test was negative; and no irritating erythema was observed on the skin after 24 hours.

[0093] Comparative Example 3 illustrates that when the mass ratio of polyolefin powder to titanium dioxide increases to 1:0.16, the excessive addition of titanium dioxide leads to increased coating strength and increased brittleness, making the coating prone to peeling during use. Peel-off rate test data shows that the peel-off rate increases significantly when the amount of titanium dioxide added is too high.

[0094] Comparative Example 4

[0095] A method for preparing a surface coating for polypropylene-based electroacupuncture acupuncture needles. The only difference between this comparative example and Example 1 is the mass ratio of the four substances: polyolefin powder, antioxidant, biocompatible material, and binder. The specific changes are as follows:

[0096] The amount of antioxidant, biocompatible material and binder added in step (3) is increased to 1g, that is, the mass ratio of the four substances, polyolefin powder, antioxidant, biocompatible material and binder, is changed to 1:0.1:0.1:0.1, and the remaining preparation steps and parameters are consistent with those in Example 1.

[0097] Finally, an insulating coating for acupuncture needles used in electroacupuncture was prepared on the surface of a stainless steel acupuncture substrate, with a relative permittivity (ε). r The dielectric strength was 3.2; the dielectric strength was 29 kV / mm; the arc resistance time was 116 s; the coating adhesion test showed a peeling rate of less than 1.5%; the in vitro cytotoxicity test showed no cytotoxicity; the skin sensitization test was negative; and no irritating erythema was observed on the skin after 24 hours.

[0098] Comparative Example 4 illustrates that when the mass ratio of polyolefin powder, antioxidant, biocompatible material, and binder is changed to 1:0.1:0.1:0.1, the increased amount of antioxidant leads to excess antioxidant precipitation during the cooling stage after thermosetting, causing the coating to easily peel off. Furthermore, the high relative dielectric constant of the biocompatible material directly increases the relative dielectric constant of the final coating, resulting in a decrease in insulation performance. The increased amount of binder leads to excessive cross-linking, making the coating prone to brittle fracture. All these factors ultimately result in a decrease in the coating's insulation performance and a certain increase in the peeling rate.

[0099] Figure 3 The relative permittivity test results of the insulating coating on the surface of acupuncture needles in Examples 1-7 and Comparative Examples 1-2 of this invention show that, except for the relative permittivity of Comparative Example 1 which increased due to the absence of binder citric acid esterified polyvinyl alcohol, the relative permittivity of the other examples is between 2.6 and 3.1, indicating that the insulating coating material prepared by this invention has good insulating properties.

[0100] Figure 4 The dielectric strength test results of the insulating coating on the surface of acupuncture needles in Examples 1-7 and Comparative Examples 1-2 of this invention show that the dielectric strength of Comparative Example 1 decreased because no binder was added and the curing temperature and curing time of Comparative Example 2 were lower. The dielectric strength of the other examples were all between 31 and 36 kV / mm, indicating that the insulating coating material prepared by this invention has good insulation performance.

[0101] Figure 5 The results of the arc resistance time test of the insulating coating on the surface of acupuncture needles in Examples 1-7 and Comparative Examples 1-2 of this invention show that the arc resistance time of Comparative Example 1 decreased because no binder was added and the curing temperature and curing time of Comparative Example 2 were lower. The arc resistance time of the other examples was all above 120s, indicating that the insulating coating material prepared by this invention has good insulation performance.

[0102] Figure 6The results of the peeling rate test of the insulating coating on the surface of acupuncture needles in Examples 1-7 and Comparative Examples 1-2 of the present invention show that, except for Comparative Example 1, where the peeling rate is significantly higher due to the absence of adhesive, the peeling rates of the other examples are all within 1%, indicating that the coating of the present invention has good durability.

[0103] Table 1 shows the skin sensitization test results of the insulating coating on the surface of acupuncture needles in Examples 1-7 and Comparative Examples 1-2 of this invention. The results indicate that the electroacupuncture surface coating prepared in this invention has almost no irritation to skin tissue.

[0104] Table 1. Allergic skin reactions in guinea pigs

[0105]

[0106] In this invention, the addition of binder is a key factor in the preparation stage of the insulating coating on the surface of acupuncture needles, affecting both insulation performance and coating durability. Without binder, the insulation performance of the coating decreases, and the peeling rate increases. Simultaneously, the curing process parameters also influence insulation performance and coating durability; as curing temperature and time decrease, the insulation performance of the coating partially declines, while the peeling rate significantly increases.

[0107] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an insulating coating on the surface of an electroacupuncture acupuncture needle, characterized in that, Includes the following steps: S1. Preparation of a mixed powder of modified polyolefin and titanium dioxide; S2. The modified polyolefin and titanium dioxide mixed powder is used to perform electrostatic spraying on the surface of the acupuncture substrate. S3. Perform heat curing treatment on the coating that has undergone high-voltage electrostatic surface spraying.

2. The method for preparing the insulating coating on the surface of electroacupuncture needles according to claim 1, characterized in that, Step S1 includes the following steps: S11. Mix the dry polyolefin powder with the swelling agent to swell the polyolefin powder; S12. Add titanium dioxide to the liquid obtained in step S11 and stir to form a homogeneous suspension. S13. Add antioxidants, biocompatible materials and binders to the suspension obtained in step S12, and heat and stir the resulting mixture under water bath conditions. S14. After cooling the mixture obtained in S13, dry it under reduced pressure to obtain the modified polyolefin and titanium dioxide mixed powder.

3. The method for preparing the insulating coating on the surface of electroacupuncture acupuncture needles according to claim 2, characterized in that, In step S11, the polyolefin is at least one of polypropylene and hydrogenated styrene-butadiene-styrene copolymer, and its polymer molecular weight is 1,000 to 100,000. And / or, in step S11, the swelling agent is at least one of xylene or cyclohexane.

4. The method for preparing the insulating coating on the surface of electroacupuncture needles according to claim 2, characterized in that, In step S11, the dried polyolefin powder and the swelling agent are contacted in a three-necked flask for 20 to 40 minutes, and the mass-volume ratio of the polyolefin powder to the swelling agent is 1 g: 8 ml. And / or, in step S12, the mass ratio of polyolefin powder to titanium dioxide is 1:(0.06~0.12).

5. The method for preparing the insulating coating on the surface of electroacupuncture needles according to claim 2, characterized in that, In step S13, the biocompatible material is at least one of esterified polyhydroxyacetic acid, polylactic acid, polycaprolactone, polysuccinate, polyβ-hydroxybutyrate, or polyurethane. And / or, the adhesive is at least one of succinimide succinate or citrate-esterified polyvinyl alcohol; And / or, the antioxidant is Irganox 1076.

6. The method for preparing the insulating coating on the surface of electroacupuncture needles according to claim 2, characterized in that, In step S13, the mass ratio of the four substances—polyolefin powder, antioxidant, biocompatible material, and binder—is 1:(0.03~0.06):(0.01~0.06):(0.01~0.06). And / or, in step S13, the water bath heating temperature is 60~80°C, and the heating time is 600~800 minutes; And / or, in step S14, the drying temperature is 70~90°C and the drying time is 15~30 h.

7. The method for preparing the insulating coating on the surface of electroacupuncture needles according to claim 1, characterized in that, After obtaining the modified polyolefin and titanium dioxide mixed powder in step S1, it is ball-milled, wherein the volume ratio of the ball milling zirconium beads to the powder is 1:1, the ball mill speed is 200~600 r / min, and the ball milling time is 8~24 h.

8. The method for preparing the insulating coating on the surface of electroacupuncture needles according to claim 7, characterized in that, In step S2, the acupuncture substrate that has undergone surface pretreatment and phosphating is electrostatically sprayed with a mixture of modified polyolefin and titanium dioxide powder after ball milling. The powder spraying rate is 100~300 g / min, the voltage of the high-voltage electrostatic generator is 40~120kV, and the current is 16 µA. The working distance between the sprayed sample and the spray gun is 300 mm.

9. The method for preparing the insulating coating on the surface of electroacupuncture acupuncture needles according to claim 1, characterized in that, In step S3, a heat curing process is performed using an oven with a uniform temperature field distribution. The curing temperature is 150~350℃ and the curing time is 20~60 min.

10. The insulating coating on the surface of an electroacupuncture acupuncture needle prepared by the method according to any one of claims 1 to 9, characterized in that, The coating has a thickness of 3~5 µm and a relative permittivity of 2.6~3.1.

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