EP4086369B1

EP4086369B1 - Method for preventing short circuiting between inner surface of capillary tube or special-shaped tube and conductive electrode

Info

Publication number: EP4086369B1
Application number: EP21893475.0A
Authority: EP
Inventors: Lidong SUN; Kaiqi ZHAO
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2020-11-23
Filing date: 2021-08-16
Publication date: 2024-10-30
Anticipated expiration: 2041-08-16
Also published as: CN112680729A; EP4086369A4; EP4086369C0; WO2022105323A1; EP4086369A1; CN112680729B

Description

TECHNICAL FIELD

The invention relates to the field of electrode material short-circuit prevention, in particular to a method for preventing short circuit of a conductive electrode for an inner surface of a capillary tube or a special-shaped tube.

BACKGROUND

Electrochemical treatment serves as one of branches of chemical treatment and is widely applied to the fields of energy, biology, environment, metal material surface modification and the like. The electrochemical reaction device is generally composed of a power supply, a cathode, an anode, an electrolyte and the like. The cathode and the anode are made of conductive materials so as to ensure conduction of system current. In an open system, the distance between the cathode and the anode is large and can be adjusted, and in the reaction process, contact caused by external force (such as bubble floating and stress of liquid flowing on the cathode and the anode) is avoided. However, for a confined semi-closed system (such as a capillary tube and a special-shaped tube), the distance between the cathode and the anode is relatively small, so that the cathode and the anode are very easy to contact under the action of external force, and the reaction cannot be smoothly carried out due to short circuit of the cathode and the anode. For example, when an electrochemical reaction method is adopted to carry out superwetting modification on the inner surface of the capillary tube or the special-shaped tube such as the capillary metal tube, the needle tube for detection, the heat dissipation copper tube for the mobile phone, the spiral titanium tube for condensation and the like, the capillary tube or the special-shaped tube serves as the anode, and a cathode filament needs to be arranged in the anode; however, the prior art can not guarantee that short circuit of the cathode filament and the capillary tube or the special-shaped tube in the reaction process will not happen, let alone preparation of the superwetting coating on the inner surface of the capillary tube or the special-shaped tube. Therefore, it is urgent to develop a method for preventing short circuit of a conductive electrode for an inner surface of a capillary tube or a shaped tube, which is convenient to operate, wide in applicability and low in cost.
WO2014/060333 discloses an elongated inner electrode for the anodic oxidation of a metal tube, around which a PVC-coated metal wire is wound.

SUMMARY

The invention aims to provide a method for preventing short circuit of a conductive electrode for an inner surface of a shaped tube, which is characterized by comprising the following steps: preparing a high-molecular polymer solution; the solvent of the solution being one of N-methylpyrrolidone (NMP) and N,N-dimethylformamide (DMF), and the solute of the solution being one of polylactic acid (PLA) and polyvinyl chloride (PVC), and cleaning and drying an electrode used for penetrating into the shaped tube, and then cladding the surface of the electrode with a high-molecular polymer. After the electrode penetrates into the shaped tube, the capillary tube or the special-shaped tube needs to be subjected to electrochemical treatment. According to the invention, the shaped tube is immersed in electrolyte to be subjected to surface treatment, the penetrated electrode serves as a cathode or an anode, and the other electrode is the shaped tube (the shaped tube and the electrode are all made of conductive materials).
Furthermore, the concentration of the high-molecular polymer solution is 10-100g/L. Furthermore, the electrode is an electrode wire made of stainless steel, copper, iron, platinum or titanium.
Furthermore, cladding of the high-molecular polymer means that the high-molecular polymer solution is coated and dried.
Furthermore, the thickness of a high-molecular polymer film cladded on the electrode is 1-50 µm.
Furthermore, the shaped tube is a capillary metal tube, a needle tube for detection, a heat dissipation copper tube for a mobile phone or a spiral titanium tube for condensation.
Furthermore, the cleaning time of the electrode is 0.5-4 hours, the drying temperature is 50-80 DEG C, and the drying time is 2-5 hours.
Furthermore, after the high-molecular polymer solution is coated, the temperature for drying the electrode is 50-80 DEG C, and the drying time is 0.5-4 hours.
Compared with the prior art, the method has the following remarkable advantages and beneficial effects:

1. The problem that the cathode and the anode are prone to short circuit in a confined semi-closed system is solved;
2. The operation is convenient, and the process production difficulty is low; and
3. The usability is wide, and the sizes and materials of the cathode and the anode are not limited.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a process schematic diagram for preparing the short-circuit-proof electrode cladded with the high-molecular polymer.
Fig. 2 is a scanning electron micrograph of the cathode filament cladded with the high-molecular polymer film. In the graphs, (a) is the surface graph of the cathode filament, (b) is the cross-sectional graph of the cathode filament, (c) is the surface graph of the film before electrochemical reaction, and (d) is the surface graph of the film after electrochemical reaction.
Fig. 3 is a scanning electron micrograph of a titanium dioxide nanotube array prepared on the inner surface of a titanium tube with the inner diameter of 0.4 mm by using an electrochemical anodic oxidation method according to the method disclosed by the invention.
Fig. 4 is the statistical result of the uniformity of the titanium dioxide nanotube array prepared on the inner surface of the titanium tube with the inner diameter of 0.4 mm and the length of 70mm by using the electrochemical anodic oxidation method according to the method disclosed by the invention.

DETAILED DESCRIPTION

The invention is further explained in combination with the following embodiments, but the subject range of the invention is not understood to be only limited to the following embodiments. Various substitutions and changes made according to the general technical knowledge and frequently used means in the art shall be included in the protection scope of the invention, which is defined by the appended claims.

Embodiment 1 (not covered by the claims)

According to the method for preventing short circuit of the conductive electrode for the inner surface of the capillary tube or the special-shaped tube, a molecular polymer solution with polyvinylidene fluoride serving as the solute and N-methylpyrrolidone serving as the solvent needs to be prepared, and the concentration of the molecular polymer solution is 10 g/L.
The method includes the following steps:

(1) ultrasonic oscillation cleaning was carried out on a stainless steel wire electrode with the diameter of 0.2 mm in a detergent, alcohol and deionized water sequentially, and the cleaning time was 0.5 h separately;
(2) the stainless steel wire was blow-dried through a nitrogen spray gun;
(3) the stainless steel wire was dried, the drying temperature was 50 DEG C, and the drying time was 1 h;
(4) the dried stainless steel wire was taken as a substrate, and the surface of the substrate was repeatedly coated with the high-molecular polymer solution for 20-25 times;
(5) the stainless steel wire coated with the polyvinylidene fluoride solution was dried, the drying temperature was 50 DEG C, and the drying time was 2 h; and
(6) the stainless steel wire was made to penetrate into a dry capillary titanium tube with the inner diameter of 0.4 mm, a power supply was connected, and the electrolyte was introduced for electrochemical treatment (anodic oxidation treatment).

Relevant performance data of the embodiment is as follows:
In a contrast experiment, the uncladded stainless steel wire with the diameter of 0.2 mm is metal, and when the uncladded stainless steel wire is independently used as a cathode in an anodic oxidation method, only 0.2 mm of residual space is left in a tube. When the electrolyte is introduced, the cathode stainless steel wire is very easy to contact with the anode capillary titanium tube to cause short circuit because the electrolyte has a scouring effect on the cathode stainless steel wire. As shown in Fig. 2, the outer surface of the treated cathode stainless steel wire is coated with a layer of high-molecular polymer diaphragm with the thickness of about 20-30 µm by cladding a high-molecular polymer film, and the layer of diaphragm can separate the cathode from the anode during anodic oxidation, so that an electric field is not shielded while short circuit is prevented, and anodic oxidation can be carried out. As shown in Fig. 3, the length of the titanium dioxide nanotube array prepared by anodic oxidation is about 3 µm, and the titanium dioxide nanotube array has the characteristics of smooth tube wall, good opening and the like. Fig. 4 shows the length statistics of the nanotube array at different positions of the inner surface of the capillary titanium type tube, which indicates that the thickness of the prepared nano coating is uniform and controllable. Meanwhile, the method has the advantages of convenience in operation, wide application range, low cost and the like.

Embodiment 2

The difference from the embodiment 1 is that:

1. In the step (1), the electrode was a platinum wire, and the diameter of the platinum wire was 0.4 mm.
2. In the step (4), polylactic acid (PLA) served as the solute of the high-molecular polymer, N-methylpyrrolidone (NMP) served as the solvent, the solution concentration was 20 g/L, and the coating number was 20-25 times.
3. In the step (6), the anode was a stainless steel capillary tube with the inner diameter of 1mm.

Embodiment 3

The difference from the embodiment 1 is that:

1. In the step (1), the electrode was a copper wire, and the diameter of the copper wire was 0.6 mm.
2. In the step (4), polyvinyl chloride (PVC) served as the solute of the high-molecular polymer, N-methylpyrrolidone (NMP) served as the solvent, the solution concentration was 10 g/L, and the coating number was 15-20 times.
3. In the step (6), the anode was an aluminum alloy capillary tube with the inner diameter of 1.5 mm.

Embodiment 4 (not covered by the claims)

The difference from the embodiment 1 is that:

1. In the step (1), the electrode was iron wire, and the diameter of the iron wire was 1mm.
2. In the step (4), polyvinylidene fluoride (PVDF) served as the solute of the high-molecular polymer, N,N-dimethylformamide (DMF) served as the solvent, the solution concentration was 15 g/L, and the coating number was 10-15 times.
3. In the step (6), the anode was a spiral capillary titanium heat exchange tube with the inner diameter of 2.5 mm.

Embodiment 5 (not covered by the claims)

The difference from the embodiment 1 is that:

1. In the step (1), the electrode was a titanium wire, and the diameter of the titanium wire was 1.5 mm.
2. In the step (6), the anode was a special-shaped copper alloy tube with a rectangular inner section (the length was 5.5 mm and the width was 3.0 mm).

Embodiment 6 (not covered by the claims)

The difference from the embodiment 1 is that:

1. In the step (1), the electrode was a titanium wire, and the diameter of the titanium wire was 0.5 mm.
2. In the step (6), the anode was an L-shaped special-shaped titanium tube with the inner diameter of 3.0 mm.

Embodiment 7 (not covered by the claims)

The difference from the embodiment 1 is that:

1. In the step (1), the electrode was an iron wire, and the diameter of the iron wire was 0.4 mm.
2. In the step (6), the anode is a T-shaped special-shaped stainless steel tube with the inner diameter of 2.5 mm.

Embodiment 8 (not covered by the claims)

The difference from the embodiment 1 is that:

1. In the step (1), the electrode was an iron wire, and the diameter of the iron wire was 0.4 mm.
2. In the step (6), the anode was a V-shaped special-shaped stainless steel tube with the inner diameter of 2.5 mm.

Claims

A method for preventing short circuit of a conductive electrode for an inner surface of a shaped tube, comprising the following steps:
preparing a high-molecular polymer solution, wherein the solvent of the solution is one selected from N-methylpyrrolidone (NMP) and N,N-dimethylformamide (DMF), and the solute of the solution is a high polymer material, which is one selected from polylactic acid (PLA), polyvinyl chloride (PVC);

cleaning and drying an electrode to be used for penetrating into the shaped tube, and then cladding the surface of the electrode with the high-molecular polymer;

using the electrode to penetrate into the shaped tube; and subjecting the shaped tube to electrochemical treatment, wherein the electrode serves as a cathode or an anode, and the shaped tube serves as the other electrode.
The method for preventing short circuit of a conductive electrode for an inner surface of a shaped tube according to claim 1, wherein the concentration of the high-molecular polymer in the solution is 10-100 g/L.
The method for preventing short circuit of a conductive electrode for an inner surface of a shaped tube according to claim 1 or 2, wherein the electrode is an electrode wire made of stainless steel, copper, iron, platinum or titanium.
The method for preventing short circuit of a conductive electrode for an inner surface of a shaped tube according to claim 1 or 3, wherein the cladding of the high-molecular polymer is produced by coating with the high-molecular polymer solution and drying.
The method for preventing short circuit of a conductive electrode for an inner surface of a shaped tube according to claim 1, wherein the high-molecular polymer cladded on the electrode forms a film of a thickness of 1-50 µm.
The method for preventing short circuit of a conductive electrode for an inner surface of a shaped tube according to claim 1, wherein the shaped tube is a capillary metal tube, a needle tube for detection, a heat dissipation copper tube for a mobile phone, or a spiral titanium tube for condensation.
The method for preventing short circuit of a conductive electrode for an inner surface of a shaped tube according to claim 1, wherein the cleaning time of the electrode is 0.5-4 hours, the drying temperature is 50-80°C, and the drying time is 2-5 hours.
The method for preventing short circuit of a conductive electrode for an inner surface of a shaped tube according to claim 1, wherein
after being coated with the high-molecular polymer solution, the electrode is dried at a temperature of 50-80°C, and the drying time is 0.5-4 hours.