Production and preparation process of microwire

Abstract

The invention discloses a production and preparation process of a microwire, belongs to the technical field of microwire processing, and is used for solving the technical problem that the flexibility, the insulating property, the high temperature resistance and the bonding fastness of the microwire need to be further improved in the prior art. The method specifically comprises the following steps: taking a copper block as a raw material, performing smelting, rolling and stretching treatment to prepare a filament conductor with the diameter of 0.13-0.15 mm, depositing a polydopamine layer formed by mixing dopamine hydrochloride and a buffer solution on the surface of the filament conductor, namely raising the temperature of a reaction system to 50-60 DEG C, performing ultrasonic dispersion, adding the filament conductor into the reaction system, and performing ultrasonic dispersion to obtain the polydopamine-based copper conductor. Carrying out heat preservation ultrasonic deposition for 3-5 hours, and carrying out post-treatment to obtain a pretreated conductor; according to the invention, the filament conductor is coated and modified by polydopamine, and is coated by the polyimide reinforcement reinforced by the polysiloxane reinforcing agent, so that the flexibility and high temperature resistance of the microfilament are effectively improved, and the bonding fastness and minimum breakdown voltage of the microfilament are also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-wire processing, and in particular to a production and preparation process of a micro-wire. Background Art

[0002] With the technological development in fields such as aerospace, microelectronics packaging, precision instruments and flexible electronic devices, the demand for fine wire materials with high flexibility, excellent insulation properties and outstanding heat resistance is becoming increasingly urgent.

[0003] In the existing technology, polyimide is mostly used as the insulating coating material for fine wires. Due to the high rigidity of the molecular chain of the polyimide insulation layer, the fine wire is prone to cracking when bent or dynamically deformed, limiting its application in high-frequency vibration or complex curved wiring scenarios. The initial decomposition temperature of conventional polyimide is usually lower than 500°C, and it is prone to thermal degradation in high-temperature environments. Moreover, the conductor and the insulation layer are bonded by physical adsorption, and are prone to peeling under thermal cycles or mechanical stress, resulting in insulation failure. It cannot meet the requirements of long-term heat resistance and high bonding strength. In addition, the breakdown voltage of traditional polyimide is limited by its molecular structure, and it is difficult to meet the high insulation strength requirements of high-voltage pulse application scenarios (such as electric vehicle motor windings).

[0004] Therefore, a solution is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a production and preparation process for fine wires, which is used to solve the technical problem in the prior art that the flexibility, insulation performance, high temperature resistance and bonding strength of fine wires need to be further improved.

[0006] The object of the present invention can be achieved by the following technical solution: A production process for fine wires, comprising the following steps: S1. Using a copper block as a raw material, a filament conductor with a diameter of 0.13-0.15 mm is prepared, and a polydopamine layer is deposited on the surface of the filament conductor to prepare a pretreated conductor; S2, mixing aniline-modified fluorinated polysiloxane, diethyl (chloromethyl) phosphine oxide, toluene, and a base catalyst, raising the temperature of the reaction system to 74-78° C., keeping the temperature for 6-8 hours, and post-treating to obtain a polysiloxane enhancer; The synthetic reaction equation of polysiloxane reinforcing agent is:

[0007] The synthetic reaction mechanism of polysiloxane reinforcing agent is: During the reaction process, a base catalyst catalyzes a nucleophilic substitution reaction between the olefin double bond on the aniline-modified fluorinated polysiloxane molecule and the halogen on the diethyl (chloromethyl) phosphine oxide molecule, thereby modifying the diethyl phosphine oxide on the aniline-modified fluorinated polysiloxane molecule. During the reaction, excessive use of diethyl (chloromethyl) phosphine oxide is controlled, and impurities are removed by reduced pressure distillation to prepare a polysiloxane enhancer.

[0008] S3, mixing and stirring a polysiloxane reinforcing agent, 4,4'-diaminodiphenyl ether, a catalyst, and DMSO, raising the temperature of the reaction system to 130-150°C, stirring until the system is dissolved, adding a pyromellitic dianhydride solution to the reaction system, keeping the temperature for reaction for 4-6 hours, and post-treating to obtain a polyimide reinforcement; The synthetic reaction mechanism of polyimide reinforcement is: During the reaction, the catalyst catalyzes the ring opening of the anhydride on the pyromellitic dianhydride molecule, reacts with the amino groups on the polysiloxane reinforcing agent and 4,4'-diaminodiphenyl ether molecules to form a polyamic acid prepolymer. The polyaniline modified on the polysiloxane reinforcing agent molecule effectively increases the intermolecular crosslinking degree of the polyamic acid prepolymer to prepare a polyimide reinforcement.

[0009] S4. Wrapping the polyimide reinforcement on the outside of the pretreated conductor, coating the outside of the pretreated conductor with a polyimide coating layer with a thickness of 10-13 μm, and subjecting the pretreated conductor to a high-temperature thermal imidization treatment to obtain fine wires.

[0010] Furthermore, the pretreated conductor is obtained by processing the following steps: A1. After melting the copper block, it is rolled and stretched to obtain a filament conductor with a diameter of 0.13-0.15 mm. A2. Dopamine hydrochloride and buffer solution were mixed, the temperature of the reaction system was raised to 50-60°C, ultrasonic dispersion was performed, a filament conductor was added to the reaction system, the system was kept warm and ultrasonically deposited for 3-5 hours, and post-processed to obtain a pretreated conductor.

[0011] The synthetic reaction mechanism of the pretreated conductor is: During the reaction process, under weakly alkaline conditions, dopamine molecules are first oxidized to dopamine quinone, and then dopamine quinone reacts with unoxidized dopamine molecules to form oligomers such as dimers and trimers, and finally polymerizes into high molecular weight polydopamine. After the filament conductor is added to the reaction bottle, polydopamine is deposited on the surface of the conductor by physical adsorption or chemical bonding. The polydopamine layer has good adhesion and can be firmly attached to the surface of the conductor to form a uniform coating, thereby preparing a pretreated conductor.

[0012] Furthermore, in step A1, the purity of the copper block is 99.98%, and in step A2, the usage ratio of the dopamine hydrochloride, the buffer solution and the filament conductor is 1g:500mL:5g, the buffer solution is a 0.3mol / L trimethylamine hydrochloride aqueous solution with a pH of 8.5, and the post-treatment includes: after the reaction is completed, removing the filament conductor from the solution, washing it with purified water and then drying it to obtain a pretreated conductor.

[0013] Furthermore, in step S2, the amount ratio of the aniline-modified fluorinated polysiloxane, diethyl (chloromethyl) phosphine oxide, toluene, and base catalyst is 5 g:2 g:50 mL:1 g, and the base catalyst is triethylamine. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is raised to 85° C., and low-boiling substances are removed by distillation under reduced pressure to obtain a polysiloxane reinforcing agent; Furthermore, in step S3, the amount ratio of the polysiloxane reinforcer, 4,4'-diaminodiphenyl ether, catalyst and DMSO is 2g:3g:0.5g:10mL, the catalyst is 4-dimethylaminopyridine, the molar ratio of the pyromellitic dianhydride to the amino group in the reaction system is 2:1, and the pyromellitic dianhydride solution is composed of pyromellitic dianhydride and DMSO at 1g:1mL. The post-treatment includes: after the reaction is completed, the reaction system is cooled to 100°C to obtain a polyimide reinforcement.

[0014] Furthermore, the preparation method of the aniline-modified fluorinated polysiloxane is as follows: D4, 2,4,6,8-tetramethyl-2,4,6,8-tetrakis(3,3,3-trifluoropropyl)cyclotetrasiloxane, aniline-modified diethoxysilane and a catalyst are mixed and stirred, the reaction system temperature is raised to 90-100°C, the reaction is kept warm for 2-3 hours, diallyltetramethyldisiloxane is added to the reaction system, the reaction is kept warm for 3-5 hours, and post-processing is performed to obtain aniline-modified fluorinated polysiloxane.

[0015] The synthetic reaction equation of aniline-modified fluorinated polysiloxane is:

[0016] Where:

[0017] The synthetic reaction mechanism of aniline-modified fluorinated polysiloxane is: During the reaction, the catalyst catalyzes the ring opening of D4 and 2,4,6,8-tetramethyl-2,4,6,8-tetra(3,3,3-trifluoropropyl)cyclotetrasiloxane molecules to form long siloxane side chains modified with silanol groups. At the same time, the siloxane bonds of the aniline-modified diethoxysilane molecules are hydrolyzed to form silanol groups. Then, dehydration condensation occurs between the silanol groups to form long siloxane chain segments modified with aniline and trifluoropropyl groups. Diallyltetramethyldisiloxane serves as an end-capping group to form an olefin end-capping modification on the long polysiloxane chain, thereby preparing aniline-modified fluorinated polysiloxane.

[0018] Furthermore, the molar ratio of D4, 2,4,6,8-tetramethyl-2,4,6,8-tetra(3,3,3-trifluoropropyl)cyclotetrasiloxane, aniline-modified diethoxysilane and diallyltetramethyldisiloxane is 3:1:1:1, the amount ratio of D4 and catalyst is 5g:1mL, the catalyst is 40-60wt% sulfuric acid, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, 0.1mol / L sodium carbonate aqueous solution is added to the reaction system, the pH of the system is adjusted to 7, the liquid is allowed to stand, the upper solution is washed twice with saturated sodium chloride solution and then washed once with purified water, the upper solution is transferred to a rotary evaporator with a water bath temperature of 75-85°C, and low-boiling substances are removed under reduced pressure to obtain aniline-modified fluorinated polysiloxane.

[0019] Furthermore, the preparation method of the aniline-modified diethoxysilane is as follows: o-phenylenediamine and tetrahydrofuran are stirred and mixed under the protection of inert gas, the temperature of the reaction system is increased to 40-50° C., 3-isocyanatepropylmethyldiethoxysilane solution is added dropwise to the reaction system, the reaction is kept warm for 60-80 minutes, and post-processed to obtain aniline-modified diethoxysilane.

[0020] The synthetic reaction equation of aniline-modified diethoxysilane is:

[0021] The synthetic reaction mechanism of aniline-modified diethoxysilane is: During the reaction, the isocyanate group on the 3-isocyanatepropylmethyldiethoxysilane molecule undergoes a condensation reaction with the amino group on the o-phenylenediamine molecule. By controlling the reaction dosage ratio and utilizing the high steric hindrance of the o-phenylenediamine molecule, aniline modification is formed on the diethoxysilane molecule to prepare aniline-modified diethoxysilane. The mass spectrometry analysis data of aniline-modified diethoxysilane are m / z: 325.18217 (100.0%), 326.18552 (16.2%), 326.18174 (5.1%), 327.17901 (3.3%), 327.18888 (1.2%), 326.17920 (1.1%).

[0022] Furthermore, the molar ratio of o-phenylenediamine and 3-isocyanatepropylmethyldiethoxysilane is 1:1, the amount ratio of o-phenylenediamine and tetrahydrofuran is 1g:4mL, the 3-isocyanatepropylmethyldiethoxysilane solution is composed of 3-isocyanatepropylmethyldiethoxysilane and tetrahydrofuran at a ratio of 1g:1mL, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is raised to 65°C, and low-boiling substances are distilled off under reduced pressure to obtain aniline-modified diethoxysilane.

[0023] Furthermore, in step S4, the method for preparing the fine wires is: B1. Immersing the pretreated conductor in a polyimide reinforcement, coating the pretreated conductor with a polyimide coating having a thickness of 10-13 μm to obtain a fine fine wire product; B2. The crude fine wires are subjected to thermal imidization treatment at a temperature of 260-280° C. for 20-30 min to obtain fine wires.

[0024] The present invention has the following beneficial effects: 1. The present invention uses polydopamine to coat and modify the copper core filament conductor, thereby reducing pinhole defects in the filament conductor, avoiding partial discharge, and ensuring the stability of the breakdown voltage. In addition, dopamine hydrochloride forms a strongly adherent polydopamine layer on the copper surface, and enhances the interfacial bonding with polyimide through hydrogen bonding and π-π stacking, so that the polyimide reinforcement can be attached to the filament conductor at a uniform temperature, and through a thermal imidization reaction, an imide ring is formed to obtain polyimide. The conjugated structure and high crystallinity of the imide ring give it excellent dielectric strength and high temperature resistance, thereby improving the minimum breakdown voltage and high temperature decomposition temperature of the fine wire.

[0025] 2. The present invention also uses a polysiloxane reinforcing agent, 4,4'-diaminodiphenyl ether and pyromellitic dianhydride to carry out an amidation reaction to prepare a polyimide reinforcement. The polysiloxane chain of the polysiloxane reinforcement molecular chain has good flexibility, giving the molecular chain a high degree of flexibility and rotational freedom. After the introduction of aniline-modified fluorinated polysiloxane, its flexible chain segments are dispersed in the rigid aromatic ring structure of the polyimide main chain, significantly improving the flexibility of the material. The trifluoropropyl modified on the polysiloxane has a low polarizability and strong hydrophobicity of its fluorine atoms, which can reduce intermolecular forces, further reduce internal friction of the material, and enhance bending tolerance. In addition, the strong electronegativity of the fluorine atom makes the CF bond have a low polarizability and high chemical inertness, inhibiting oxidation reactions and free radical chain reactions, and delaying thermal decomposition. In addition, the fluorine atom can stabilize the Si-O-Si main chain through a steric hindrance effect, reducing the tendency of the siloxane chain to break at high temperatures, thereby compensating for the insufficient high-temperature stability of polysilane.

[0026] 3. The present invention also modifies the aniline-modified fluorinated polysiloxane molecule with diethylphosphine oxide, which can decompose to produce phosphoric acid substances at high temperatures. This promotes the formation of a carbon layer through a condensed phase flame retardant mechanism, thereby isolating heat and oxygen and delaying the thermal decomposition process of the material. The synergistic effect of phosphorus and fluorine may further enhance the density and stability of the carbon layer, thereby increasing the thermal decomposition temperature. The aniline on the polysiloxane reinforcing agent serves as an active reaction site for the amidation reaction, increasing the cross-linking degree between the reacting molecules, restricting the movement of the polymer chain segments, and reducing the chain breakage tendency in the early stage of thermal decomposition, thereby improving thermal stability and breakdown voltage. In addition, the strong electronegativity of the trifluoropropyl group can also inhibit charge migration and improve the dielectric strength. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] In the present invention, D4 is octamethylcyclotetrasiloxane, CAS number is 556-67-2; In the present invention, DMSO is dimethyl sulfoxide, and its CAS number is 67-68-5.

[0029] Example 1 This embodiment provides a method for preparing a polyimide reinforcement, comprising the following steps: Step 1: Preparation of aniline-modified diethoxysilane Weigh and mix 21.7 g of 3-isocyanatopropylmethyldiethoxysilane and 21.7 mL of tetrahydrofuran to obtain a 3-isocyanatopropylmethyldiethoxysilane solution for later use. Weigh: 10.8 g of o-phenylenediamine and 43.2 mL of tetrahydrofuran were added to a reaction flask protected by argon and stirred. The temperature of the reaction flask was raised to 40°C. The mixed 3-isocyanatepropylmethyldiethoxysilane solution was added dropwise to the reaction flask. After the addition was complete, the mixture was kept warm for 60 minutes. The temperature of the reaction flask was raised to 65°C, and low-boiling substances were evaporated under reduced pressure to obtain aniline-modified diethoxysilane.

[0030] Step 2: Preparation of aniline-modified fluorinated polysiloxane Weigh: 89.0 g of D4, 62.5 g of 2,4,6,8-tetramethyl-2,4,6,8-tetra(3,3,3-trifluoropropyl)cyclotetrasiloxane, 32.5 g of aniline-modified diethoxysilane and 17.8 mL of 40 wt% sulfuric acid, add them to a reaction flask and stir, raise the temperature of the reaction flask to 90 ° C, keep warm and react for 2 hours, add 21.4 g of diallyltetramethyldisiloxane to the reaction flask, keep warm and react for 3 hours, lower the temperature of the reaction flask to room temperature, add 0.1 mol / L sodium carbonate aqueous solution to the reaction flask, adjust the pH of the system to 7, let it stand and separate, wash the upper solution twice with saturated sodium chloride solution and then wash once with purified water, transfer the upper solution to a rotary evaporator with a water bath temperature of 75 ° C, and remove low boiling points under reduced pressure to obtain aniline-modified fluorinated polysiloxane.

[0031] Step 3: Preparation of polysiloxane reinforcing agent Weigh: 200 g of aniline-modified fluorinated polysiloxane, 80 g of diethyl (chloromethyl) phosphine oxide, 2000 mL of toluene, and 40 g of alkaline catalyst triethylamine, add them to a reaction flask and stir, raise the temperature of the reaction flask to 74°C, keep the reaction warm for 6 hours, raise the temperature of the reaction flask to 85°C, and remove low-boiling substances under reduced pressure to obtain a polysiloxane enhancer.

[0032] Step 4: Preparation of polyimide reinforcement Weigh: 100 g of polysiloxane reinforcing agent, 150 g of 4,4'-diaminodiphenyl ether, 25 g of catalyst 4-dimethylaminopyridine and 500 mL of DMSO, add them to a reaction flask and stir. The temperature of the reaction flask is raised to 130°C and stirred until the system is dissolved. The amount of pyromellitic dianhydride added is calculated according to 1 / 2 of the molar amount of the amino group of the reactants in the reaction flask, and pyromellitic dianhydride and DMSO are mixed at a ratio of 1 g:1 mL to obtain a pyromellitic dianhydride solution. The pyromellitic dianhydride solution is added dropwise to the reaction flask. After the addition is complete, the reaction is kept warm for 4 hours, and after post-treatment, the reaction flask is cooled to 100°C to obtain a polyimide reinforcement.

[0033] Example 2 This embodiment provides a method for preparing a polyimide reinforcement, comprising the following steps: Step 1: Preparation of aniline-modified diethoxysilane Weigh and mix 21.7 g of 3-isocyanatopropylmethyldiethoxysilane and 21.7 mL of tetrahydrofuran to obtain a 3-isocyanatopropylmethyldiethoxysilane solution for later use. Weigh: 10.8 g of o-phenylenediamine and 43.2 mL of tetrahydrofuran were added to a reaction flask protected by argon and stirred. The temperature of the reaction flask was raised to 45°C. The mixed 3-isocyanatepropylmethyldiethoxysilane solution was added dropwise to the reaction flask. After the addition was complete, the mixture was kept warm for 70 minutes. The temperature of the reaction flask was raised to 65°C, and low-boiling substances were evaporated under reduced pressure to obtain aniline-modified diethoxysilane.

[0034] Step 2: Preparation of aniline-modified fluorinated polysiloxane Weigh: 89.0 g of D4, 62.5 g of 2,4,6,8-tetramethyl-2,4,6,8-tetra(3,3,3-trifluoropropyl)cyclotetrasiloxane, 32.5 g of aniline-modified diethoxysilane and 17.8 mL of 50 wt% sulfuric acid, add them to a reaction flask and stir, raise the temperature of the reaction flask to 95 ° C, keep the reaction warm for 2.5 hours, add 21.4 g of diallyltetramethyldisiloxane to the reaction flask, keep the reaction warm for 4 hours, lower the temperature of the reaction flask to room temperature, add 0.1 mol / L sodium carbonate aqueous solution to the reaction flask, adjust the pH of the system to 7, let it stand and separate, wash the upper solution twice with saturated sodium chloride solution and then wash once with purified water, transfer the upper solution to a rotary evaporator with a water bath temperature of 80 ° C, and remove low boiling points under reduced pressure to obtain aniline-modified fluorinated polysiloxane.

[0035] Step 3: Preparation of polysiloxane reinforcing agent Weigh: 200 g of aniline-modified fluorinated polysiloxane, 80 g of diethyl (chloromethyl) phosphine oxide, 2000 mL of toluene, and 40 g of alkaline catalyst triethylamine, add them to a reaction flask and stir, raise the temperature of the reaction flask to 76°C, keep the reaction warm for 7 hours, raise the temperature of the reaction flask to 85°C, and remove low-boiling substances under reduced pressure to obtain a polysiloxane enhancer.

[0036] Step 4: Preparation of polyimide reinforcement Weigh: 100 g of polysiloxane reinforcing agent, 150 g of 4,4'-diaminodiphenyl ether, 25 g of catalyst 4-dimethylaminopyridine and 500 mL of DMSO, add them to a reaction flask and stir. The temperature of the reaction flask is raised to 140°C and stirred until the system is dissolved. The amount of pyromellitic dianhydride added is calculated according to 1 / 2 of the molar amount of the amino group of the reactants in the reaction flask, and pyromellitic dianhydride and DMSO are mixed at a ratio of 1 g:1 mL to obtain a pyromellitic dianhydride solution. The pyromellitic dianhydride solution is added dropwise to the reaction flask. After the addition is complete, the reaction is kept warm for 5 hours, and after post-treatment, the reaction flask is cooled to 100°C to obtain a polyimide reinforcement.

[0037] Example 3 This embodiment provides a method for preparing a polyimide reinforcement, comprising the following steps: Step 1: Preparation of aniline-modified diethoxysilane Weigh and mix 21.7 g of 3-isocyanatopropylmethyldiethoxysilane and 21.7 mL of tetrahydrofuran to obtain a 3-isocyanatopropylmethyldiethoxysilane solution for later use. Weigh: 10.8 g of o-phenylenediamine and 43.2 mL of tetrahydrofuran were added to a reaction flask protected by argon and stirred. The temperature of the reaction flask was raised to 50°C. The mixed 3-isocyanatepropylmethyldiethoxysilane solution was added dropwise to the reaction flask. After the addition was complete, the mixture was kept warm for 80 minutes. The temperature of the reaction flask was raised to 65°C, and low-boiling substances were evaporated under reduced pressure to obtain aniline-modified diethoxysilane.

[0038] Step 2: Preparation of aniline-modified fluorinated polysiloxane Weigh: 89.0 g of D4, 62.5 g of 2,4,6,8-tetramethyl-2,4,6,8-tetra(3,3,3-trifluoropropyl)cyclotetrasiloxane, 32.5 g of aniline-modified diethoxysilane and 17.8 mL of 60 wt % sulfuric acid, add them to a reaction flask and stir, raise the temperature of the reaction flask to 100 ° C, keep warm and react for 3 hours, add 21.4 g of diallyltetramethyldisiloxane to the reaction flask, keep warm and react for 5 hours, lower the temperature of the reaction flask to room temperature, add 0.1 mol / L sodium carbonate aqueous solution to the reaction flask, adjust the pH of the system to 7, let it stand and separate, wash the upper solution twice with saturated sodium chloride solution and then wash once with purified water, transfer the upper solution to a rotary evaporator with a water bath temperature of 85 ° C, and remove low boiling points under reduced pressure to obtain aniline-modified fluorinated polysiloxane.

[0039] Step 3: Preparation of polysiloxane reinforcing agent Weigh: 200 g of aniline-modified fluorinated polysiloxane, 80 g of diethyl (chloromethyl) phosphine oxide, 2000 mL of toluene, and 40 g of alkaline catalyst triethylamine, add them to a reaction flask and stir, raise the temperature of the reaction flask to 78°C, keep the reaction warm for 8 hours, raise the temperature of the reaction flask to 85°C, and remove low-boiling substances under reduced pressure to obtain a polysiloxane enhancer.

[0040] Step 4: Preparation of polyimide reinforcement Weigh: 100 g of polysiloxane reinforcing agent, 150 g of 4,4'-diaminodiphenyl ether, 25 g of catalyst 4-dimethylaminopyridine and 500 mL of DMSO, add them to a reaction flask and stir. The temperature of the reaction flask is raised to 150°C and stirred until the system is dissolved. The amount of pyromellitic dianhydride added is calculated according to 1 / 2 of the molar amount of the amino group of the reactants in the reaction flask, and pyromellitic dianhydride and DMSO are mixed at a ratio of 1 g:1 mL to obtain a pyromellitic dianhydride solution. The pyromellitic dianhydride solution is added dropwise to the reaction flask. After the addition is complete, the reaction is kept warm for 6 hours, and after post-treatment, the reaction flask is cooled to 100°C to obtain a polyimide reinforcement.

[0041] Example 4 This embodiment provides a production process for fine wires, including the following steps: Step I: Preparation of thin wire conductor After melting a copper block with a purity of 99.98%, it is rolled and stretched to obtain a filament conductor with a diameter of 0.13mm. Step II: Preparation of pre-treated conductor Mix trimethylamine hydrochloride and deionized water evenly and adjust the pH to 8.5 to obtain a buffer solution with a concentration of 0.3 mol / L, which is then set aside. Weigh: 10 g of dopamine hydrochloride and 5 L of buffer solution are added to a reaction flask and mixed. The temperature of the reaction flask is raised to 50°C and ultrasonic dispersion is performed. 50 g of a filament conductor is added to the reaction flask and ultrasonic deposition is performed for 3 hours at a temperature preservation temperature. The filament conductor is removed from the solution, washed with purified water, and then dried to obtain a pretreated conductor.

[0042] Step III: Preparation of fine lines The pretreated conductor was immersed in the polyimide reinforcement prepared in Example 1, and a polyimide coating layer with a thickness of 10 μm was coated on the outside of the pretreated conductor to prepare a fine fine wire rough product; The crude fine wires were transferred to a drying oven at 260° C. and subjected to thermal imidization treatment for 30 min to obtain fine wires.

[0043] Example 5 This embodiment provides a production process for fine wires, including the following steps: Step I: Preparation of thin wire conductor After melting a copper block with a purity of 99.98%, it is rolled and stretched to obtain a filament conductor with a diameter of 0.14mm. Step II: Preparation of pre-treated conductor Mix trimethylamine hydrochloride and deionized water evenly and adjust the pH to 8.5 to obtain a buffer solution with a concentration of 0.3 mol / L, which is then set aside. Weigh: 10 g of dopamine hydrochloride and 5 L of buffer solution are added to a reaction flask and mixed. The temperature of the reaction flask is raised to 55°C and ultrasonic dispersion is performed. 50 g of a filament conductor is added to the reaction flask and ultrasonic deposition is performed for 4 hours. The filament conductor is removed from the solution, washed with purified water, and then dried to obtain a pretreated conductor.

[0044] Step III: Preparation of fine wires The pretreated conductor was immersed in the polyimide reinforcement prepared in Example 2, and a polyimide coating layer with a thickness of 12 μm was coated on the outside of the pretreated conductor to prepare a fine fine wire rough product; The crude fine wires were transferred to a drying oven at 270° C. and subjected to thermal imidization treatment for 25 min to obtain fine wires.

[0045] Example 6 This embodiment provides a production process for fine wires, including the following steps: Step I: Preparation of thin wire conductor After melting a copper block with a purity of 99.98%, it is rolled and stretched to obtain a filament conductor with a diameter of 0.15mm; Step II: Preparation of pre-treated conductor Mix trimethylamine hydrochloride and deionized water evenly and adjust the pH to 8.5 to obtain a buffer solution with a concentration of 0.3 mol / L, which is then set aside. Weigh: 10 g of dopamine hydrochloride and 5 L of buffer solution are added to a reaction flask and mixed. The temperature of the reaction flask is raised to 60°C and ultrasonic dispersion is performed. 50 g of a filament conductor is added to the reaction flask, and ultrasonic deposition is performed for 5 hours at a temperature of 5°C. The filament conductor is removed from the solution, washed with purified water, and then dried to obtain a pretreated conductor.

[0046] Step III: Preparation of fine wires The pretreated conductor was immersed in the polyimide reinforcement prepared in Example 3, and a polyimide coating layer with a thickness of 13 μm was coated on the outside of the pretreated conductor to prepare a fine fine wire rough product; The crude fine wires were transferred to a drying oven at 280° C. and subjected to thermal imidization treatment for 20 min to obtain fine wires.

[0047] Comparative Example 1 The difference between this comparative example and Example 6 is that, in the preparation process of the polyimide reinforcement used, in step 2, 2, 4, 6, 8-tetramethyl-2, 4, 6, 8-tetrakis (3, 3, 3-trifluoropropyl) cyclotetrasiloxane is replaced by D4 in an equal molar amount.

[0048] Comparative Example 2 The difference between this comparative example and Example 6 is that, in the preparation process of the polyimide reinforcement used, step 3 is omitted, and the polysiloxane reinforcing agent in step 4 is replaced by the aniline-modified fluorinated polysiloxane in step 2.

[0049] Comparative Example 3 The difference between this comparative example and Example 6 is that step II is omitted, and the pretreated conductor in step III is replaced by the filament conductor in step I.

[0050] Performance testing: The flexibility and breakdown voltage of the fine wire samples prepared in Examples 4-6 and Comparative Examples 1-3 were measured with reference to the standard GB / T 6109.1-2008 "Enameled Round Winding Wire Part 1: General Provisions"; Flexibility is measured by winding the sample onto a round rod with a diameter of 0.150 mm after different stretches, and measuring the maximum tensile elongation before the paint layer of the sample cracks (winding elongation) and the elongation of the paint layer on the sample surface when it breaks (breaking elongation); The breakdown voltage is the minimum breakdown voltage of the sample at room temperature; The bonding strength grades of the fine line specimens prepared in Examples 4-6 and Comparative Examples 1-3 were determined with reference to the standard GB / T 1720-2020 "Paint Film Circle Test"; The sample was placed in a thermogravimetric analyzer, the atmosphere was set to air, the temperature range was from room temperature to 800°C, the heating rate was 10°C / min, and the initial decomposition temperature of the sample was measured. The specific test results are shown in Table 1 below.

[0051] Table 1-Performance test data of the sample

[0052] Data Analysis: A comparative analysis of the data in Table 1 above shows that the winding elongation of the microfilaments prepared by the present invention reaches 25.8%, the elongation at break reaches 36.9%, the minimum breakdown voltage reaches 1700V, the bonding strength level of the surface paint film layer reaches level 2, and the initial decomposition temperature reaches 555°C. The performance test data are all better than those of the comparative example, indicating that the present invention modifies the aniline-modified fluorinated polysiloxane with diethylphosphine oxide to prepare a polysiloxane reinforcer to reinforce the polyimide reinforcement, and then coats the polydopamine-modified filament conductor, which not only effectively improves the flexibility and high temperature resistance of the microfilaments, but also improves their bonding strength and minimum breakdown voltage.

[0053] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A production process for fine wires, characterized in that: The following steps are involved: S1. Using a copper block as a raw material, a filament conductor with a diameter of 0.13-0.15 mm is prepared by smelting, rolling, and stretching. A polydopamine layer formed by a mixture of dopamine hydrochloride and a buffer solution is deposited on the surface of the filament conductor. That is, the reaction system temperature is raised to 50-60°C, ultrasonic dispersion is performed, the filament conductor is added to the reaction system, and ultrasonic deposition is performed for 3-5 hours at this temperature. Post-treatment is performed to obtain a pretreated conductor. S2, D4, 2,4,6,8-tetramethyl-2,4,6,8-tetrakis(3,3,3-trifluoropropyl)cyclotetrasiloxane, aniline-modified diethoxysilane and a catalyst were mixed and stirred, the reaction system temperature was raised to 90-100°C, and the reaction was kept warm for 2-3 hours. Diallyltetramethyldisiloxane was added to the reaction system, and the reaction was kept warm for 3-5 hours. After post-treatment, aniline-modified fluorinated polysiloxane was obtained, which was mixed and stirred with diethyl(chloromethyl)phosphine oxide, toluene and an alkali catalyst. The reaction system temperature was raised to 74-78°C, and the reaction was kept warm for 6-8 hours. After post-treatment, a polysiloxane enhancer was obtained. S3, mixing and stirring a polysiloxane reinforcing agent, 4,4'-diaminodiphenyl ether, a catalyst, and DMSO, raising the temperature of the reaction system to 130-150°C, stirring until the system is dissolved, adding a pyromellitic dianhydride solution to the reaction system, keeping the temperature for reaction for 4-6 hours, and post-treating to obtain a polyimide reinforcement; S4. Wrapping the polyimide reinforcement on the outside of the pretreated conductor, coating the outside of the pretreated conductor with a polyimide coating layer with a thickness of 10-13 μm, and subjecting the pretreated conductor to a high-temperature thermal imidization treatment to obtain fine wires.

2. The process for producing a fine wire according to claim 1, characterized in that: In step S1, the purity of the copper block is 99.98%, the usage ratio of the dopamine hydrochloride, the buffer solution and the filament conductor is 1 g:500 mL:5 g, and the buffer solution is a 0.3 mol / L trimethylamine hydrochloride aqueous solution with a pH of 8.

5.

3. The process for producing a fine wire according to claim 1, wherein: In step S2, the usage ratio of the aniline-modified fluorinated polysiloxane, diethyl (chloromethyl) phosphine oxide, toluene, and base catalyst is 5 g:2 g:50 mL:1 g, and the base catalyst is triethylamine.

4. The process for producing a fine wire according to claim 1, wherein: In step S2, the molar ratio of D4, 2,4,6,8-tetramethyl-2,4,6,8-tetrakis(3,3,3-trifluoropropyl)cyclotetrasiloxane, aniline-modified diethoxysilane and diallyltetramethyldisiloxane is 3:1:1:1, the amount ratio of D4 and catalyst is 5 g:1 mL, and the catalyst is 40-60 wt% sulfuric acid.

5. The process for producing a fine wire according to claim 4, characterized in that: The preparation method of the aniline-modified diethoxysilane comprises the following steps: stirring and mixing o-phenylenediamine and tetrahydrofuran under inert gas protection, raising the temperature of the reaction system to 40-50° C., adding dropwise 3-isocyanatepropylmethyldiethoxysilane solution to the reaction system, keeping the temperature for reaction for 60-80 minutes, and performing post-treatment to obtain the aniline-modified diethoxysilane.

6. A process for producing a fine wire according to claim 5, characterized in that: The molar ratio of the o-phenylenediamine and 3-isocyanatepropylmethyldiethoxysilane is 1:1, the usage ratio of the o-phenylenediamine and tetrahydrofuran is 1g:4mL, and the 3-isocyanatepropylmethyldiethoxysilane solution is composed of 3-isocyanatepropylmethyldiethoxysilane and tetrahydrofuran at a ratio of 1g:1mL.

7. The process for producing a fine wire according to claim 1, characterized in that: In step S3, the polysiloxane enhancer, 4,4'-diaminodiphenyl ether, catalyst and DMSO are used in a ratio of 2 g:3 g:0.5 g:10 mL, the catalyst is 4-dimethylaminopyridine, the molar ratio of pyromellitic dianhydride to amino groups in the reaction system is 2:1, and the pyromellitic dianhydride solution is composed of pyromellitic dianhydride and DMSO at a ratio of 1 g:1 mL.

8. The process for producing a fine wire according to claim 1, characterized in that: In step S4, the method for preparing the fine wires is as follows: B1. Immersing the pretreated conductor in a polyimide reinforcement, coating the pretreated conductor with a polyimide coating having a thickness of 10-13 μm to obtain a fine fine wire product; B2. The crude fine wires are subjected to thermal imidization treatment at a temperature of 260-280° C. for 20-30 min to obtain fine wires.

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