Preparation method of thermosetting polyether coating copper core enameled wire

Abstract

The invention relates to the technical field of enameled wires, in particular to a preparation method of a thermosetting polyether coating copper core enameled wire, which comprises the following steps: dissolving polyether in an organic solvent, adding PAMAM (Polyamidoamine) dendrimer, adding a diluent while heating and stirring, uniformly stirring, and keeping the temperature at low temperature to prepare a polyether mixed emulsion; keeping the low temperature, adding diisocyanate and an organic tin catalyst into the obtained polyether mixed emulsion, uniformly stirring, transferring into a painting tank, and enabling a copper wire to pass through the painting tank at a constant speed; and enabling the painted copper wire to pass through a negative-pressure constant-temperature box at a constant speed, heating the copper wire, drying the copper wire through water vapor, and packaging the copper wire to obtain the thermosetting polyether-coated copper-core enameled wire. The polyether and the PAMAM are prepared into the mixed emulsion and then mixed with the diisocyanate, the polyether, the PAMAM and the diisocyanate are subjected to random polymerization reaction under the action of the catalyst after being heated, a uniform and compact net-shaped polyether coating is generated on the surface of the copper core, and the adhesive force, the heat resistance and the friction resistance of the coating are obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of enameled wires, and in particular to a method for preparing a thermosetting polyether coated copper core enameled wire. Background Art

[0002] Enameled wire is a conductor coated with an insulating varnish and used to wind coils. Friction-resistant enameled wire is subject to friction during production and use, such as during winding and insertion into motor slots, and therefore requires superior wear resistance. During service, corrosion is inevitable due to the relatively complex environment it encounters. Therefore, enameled wire must possess both friction resistance and long-lasting corrosion resistance.

[0003] Traditional enameled wires are often coated with polyester, polyurethane, or polyimide, which can suffer from insufficient temperature resistance (typically ≤180°C), high dielectric loss in high-frequency environments, and poor flexibility. Polyether resins, due to the ether bonds in their molecular chains, offer excellent thermal stability and flexibility, but existing polyether coatings suffer from poor adhesion and slow curing. Summary of the Invention

[0004] In view of the above problems existing in the existing polyether enameled wire, the present invention provides a method for preparing a thermosetting polyether coated copper core enameled wire, comprising the following steps: 1. Prepare polyether mixed emulsion Dissolve the polyether in an organic solvent, add the PAMAM dendrimer, add the diluent while heating and stirring, stir evenly and keep the mixture at low temperature to prepare a polyether mixed emulsion; 2. Painting Keeping the temperature low, add diisocyanate and organotin catalyst to the polyether mixed emulsion obtained in step 1, stir evenly and transfer to a coating tank, and pass the copper wire through the coating tank at a constant speed; 3. Shaped roll packaging The copper wire painted in step 2 is passed through a negative pressure constant temperature box at a uniform speed, heated, passed through water vapor, dried, and wound to obtain a thermosetting polyether coated copper core enameled wire.

[0005] The copper core used in the present invention has a diameter of 0.05-5 mm and needs to be pretreated on the surface to improve the adhesion of the coating. The pretreatment specifically comprises the following steps: placing the copper core in a pickling tank, performing pickling with a mixed solution of sulfuric acid and a corrosion inhibitor to remove oxides and oil stains on the surface of the copper core, and rinsing with clean water after pickling; placing the copper core in an alkali washing tank, performing alkali washing with a sodium hydroxide solution to further remove oil stains and impurities, and rinsing with clean water after alkali washing; and finally performing electrolytic polishing on the copper core to improve the surface smoothness and adhesion of the copper core. The treated copper core can then be used for subsequent coating preparation.

[0006] Specifically, in step 1, the organic solvent is selected from DMSO, DMAc, N-methyl-2-pyrrolidone, 2-butanol, or methyl acetate; the diluent is selected from acetone, butanone, cyclohexanone, or ethyl acetate; and the low-temperature temperature is 0-10°C. When preparing the polyether emulsion, the selection of these solvents and diluents, as well as the control of low-temperature conditions, are crucial to the performance of the final product. Organic solvents such as DMSO and DMAc have excellent solubility properties, ensuring uniform dispersion of the polyether resin and other additives in the solution. Solvents such as N-methyl-2-pyrrolidone, 2-butanol, and methyl acetate have specific volatility and surface tension, which help adjust the coating's drying speed and final gloss. The choice of diluent is equally important, as it adjusts the viscosity of the polyether emulsion, making it more suitable for subsequent coating preparation. Diluents such as acetone, butanone, cyclohexanone, and ethyl acetate have varying volatility and solubility, and can be selected based on specific needs to achieve optimal coating results and process performance. Controlling low temperatures is also a key step in the preparation process. Keeping the temperature within the 0-10°C range helps slow the curing of the polyether emulsion, ensuring uniform coverage of the coating on the copper core during painting. Low temperatures also help reduce solvent evaporation and coating shrinkage, further improving coating adhesion and quality.

[0007] The PAMAM used in the present invention has a number-average molecular weight of 1000-2000. As a crosslinking agent, PAMAM can effectively increase the degree of crosslinking between polyether resin molecules, thereby enhancing the thermal stability and mechanical strength of the coating. During the shaping and packaging process, the introduction of PAMAM enables the coating to cure better, forming a denser and tougher coating structure. PAMAM also has a certain lubricity, which helps reduce friction and damage to the coating during the packaging process, thereby improving the yield and quality of the product. By precisely controlling the amount of PAMAM added and the shaping and packaging process parameters, the performance and process stability of the coating can be further optimized.

[0008] The polyethers of the present invention are specifically selected from polyethylene glycol (PEG)-based polyethers or polypropylene glycol (PPG)-based polyethers. These polyethers exhibit excellent flexibility and abrasion resistance, effectively enhancing the elasticity and durability of the coating. Furthermore, they exhibit excellent compatibility with the PAMAM crosslinker, ensuring a stable and uniform coating structure during the shaping and packaging process. By selecting the appropriate polyether type and molecular weight, the coating's performance can be further optimized to meet the needs of diverse applications.

[0009] Specifically, in step 2, the diisocyanate is selected from one of MDI, TDI, HDI, and HMDI. In the shaping and wrapping stage, the use of a diisocyanate as a cross-linking agent can effectively enhance the cross-linking density and hardness of the coating, thereby improving the wear resistance and heat resistance of the enameled wire. Different types of diisocyanates such as MDI, TDI, HDI, and HMDI have different reactivities and physical properties and can be selected according to specific application requirements. For example, MDI has a higher cross-linking density and hardness and is suitable for applications requiring high strength and wear resistance, while HDI has better flexibility and weather resistance and is suitable for applications requiring higher flexibility and weather resistance of the coating. By selecting the appropriate diisocyanate, the performance of the enameled wire can be further optimized to meet different application requirements.

[0010] Specifically, in step three, the pressure of the negative pressure thermostat is 100~500Pa, and the temperature is 50~65℃. During the shaping and packaging process in the negative pressure thermostat, appropriate pressure and temperature control is crucial to obtaining high-quality coatings. The pressure range of 100~500Pa can effectively eliminate bubbles in the coating, avoid pinholes and defects in the coating, and thus improve the density and smoothness of the coating. The temperature range of 50~65℃ is conducive to the rapid curing of the coating, reducing the curing time, and avoiding excessive shrinkage and deformation of the coating caused by excessive temperature. By precisely controlling the pressure and temperature of the negative pressure thermostat, it is possible to ensure that the coating obtains the best physical properties and appearance quality during the shaping and packaging stage.

[0011] Compared with existing polyether enameled wires, the special feature of the present invention is that: polyether and PAMAM are prepared into a mixed emulsion and then mixed with diisocyanate. After heating, the three will undergo a random polymerization reaction under the action of a catalyst, forming a uniform and dense network polyether coating on the surface of the copper core, which significantly improves the adhesion, heat resistance and friction resistance of the coating. DETAILED DESCRIPTION

[0012] The present invention is described below with reference to examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0013] Example 1 A method for preparing a thermosetting polyethylene glycol-based polyether coated copper core enameled wire comprises the following steps: 1. Disperse 100 parts by weight of polyethylene glycol-based polyether with a molecular weight between 1000 and 3000 in 200 parts by weight of DMSO, add 30 parts by weight of PAMAM with a molecular weight of 1500 and 15 parts by weight of ethyl acetate, stir evenly at 60°C, and then cool to 5°C for storage to obtain a polyether mixed emulsion; 2. Maintaining the temperature at 5°C, add 50 parts by weight of MDI and 3 parts by weight of an organotin catalyst to the obtained polyether mixed emulsion, stir evenly, and transfer to a coating tank. Pass a copper wire with a diameter of 2 mm through the coating tank at a constant speed of 6 m / s. 3. The painted copper wire is passed through a negative pressure constant temperature box of 100 Pa and 55°C at a constant speed of 4m / s, then dried after passing through water vapor, and wound to obtain a thermosetting polyether coated copper core enameled wire.

[0014] Example 2 A method for preparing a thermosetting polypropylene glycol-based polyether coated copper core enameled wire comprises the following steps: 1. Disperse 100 parts by weight of polypropylene glycol-based polyether with a molecular weight between 1000 and 3000 in 250 parts by weight of DMAc, add 50 parts by weight of PAMAM with a molecular weight of 2000 and 10 parts by weight of acetone, stir evenly at 70°C, and then cool to 0°C for storage to obtain a polyether mixed emulsion; 2. Maintaining 0°C, add 60 parts by weight of TDI and 5 parts by weight of an organotin catalyst to the obtained polyether mixed emulsion, stir evenly, and transfer to a coating tank. Pass a 5 mm diameter copper wire through the coating tank at a constant speed of 5 m / s; 3. The painted copper wire is passed through a negative pressure constant temperature box at a constant speed of 500Pa and 65°C at a constant speed of 3m / s, then passed through water vapor and dried, and wound to obtain a thermosetting polyether coated copper core enameled wire.

[0015] Example 3 A method for preparing a thermosetting polyethylene glycol-based polyether coated copper core enameled wire comprises the following steps: 1. Disperse 100 parts by weight of a polyethylene glycol-based polyether with a molecular weight between 1000 and 3000 in 300 parts by weight of N-methyl-2-pyrrolidone, add 50 parts by weight of PAMAM with a molecular weight of 1000 and 5 parts by weight of cyclohexanone, stir evenly at 50°C, and then cool to 10°C for storage to obtain a polyether mixed emulsion; 2. Maintaining the temperature at 10°C, add 40 parts by weight of HDI and 4 parts by weight of an organotin catalyst to the obtained polyether mixed emulsion, stir evenly, and transfer to a coating tank. Pass a copper wire with a diameter of 1 mm through the coating tank at a constant speed of 8 m / s. 3. The painted copper wire is passed through a negative pressure constant temperature box at 200 Pa and 50°C at a constant speed of 5m / s, then passed through water vapor and dried, and wound to obtain a thermosetting polyether coated copper core enameled wire.

[0016] Comparative Examples 1 to 3 are polyether-coated copper core enameled wires prepared in Examples 1 to 3 without adding PAMAM.

[0017] The upper heat resistance limits of the thermosetting polyether-coated copper core enameled wires obtained in Examples 1 to 3 and the polyether-coated copper core enameled wires obtained in Comparative Examples 1 to 3 are 262°C, 258°C, 264°C, 220°C, 215°C, and 217°C, respectively. This shows that the fibers added with PAMAM exhibit higher heat resistance in the prepared enameled wires, which further demonstrates the effectiveness of PAMAM in improving the comprehensive performance of the enameled wires.

[0018] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a thermosetting polyether coated copper core enameled wire, characterized in that: The following steps are involved:

1. Prepare polyether mixed emulsion Dissolve the polyether in an organic solvent, add the PAMAM dendrimer, add the diluent while heating and stirring, stir evenly and keep the mixture at low temperature to prepare a polyether mixed emulsion; 2. Painting Keeping the temperature low, add diisocyanate and organotin catalyst to the polyether mixed emulsion obtained in step 1, stir evenly and transfer to a coating tank, and pass the copper wire through the coating tank at a constant speed; 3. Shaped roll packaging The copper wire painted in step 2 is passed through a negative pressure constant temperature box at a uniform speed, heated, passed through water vapor, dried, and wound to obtain a thermosetting polyether coated copper core enameled wire.

2. The method according to claim 1, characterized in that The diameter of the copper core is 0.05-5 mm.

3. The method according to claim 2, characterized in that In step 1, the organic solvent is selected from one of DMSO, DMAc, N-methyl-2-pyrrolidone, 2-butanol or methyl acetate.

4. The method according to claim 2, characterized in that In step 1, the diluent is selected from one of acetone, butanone, cyclohexanone or ethyl acetate.

5. The method according to claim 2, characterized in that In step 1, the low temperature is 0~10℃.

6. The method according to claim 2, characterized in that In step 2, the diisocyanate is selected from one of MDI, TDI, HDI and HMDI.

7. The method according to claim 2, characterized in that In step 3, the pressure of the negative pressure constant temperature box is 100~500Pa, and the temperature is 50~65℃.