Preparation method of modified polyamide composite coating enameled wire

Abstract

The invention relates to the technical field of varnished wires, in particular to a preparation method of a modified polyamide composite coating varnished wire, which comprises four steps of preparing modified polyamide mixed slurry, sizing, sizing and annealing and packaging. Polyamine is grafted to one end, with carboxyl, of the polyamide oligomer, so that the two ends of the polyamide oligomer are amino groups, the polyamide oligomer can continue to react with diisocyanate, due to the addition of the triamino compound, a net-shaped product with a certain proportion can be formed, and the aging resistance is improved; the shaped paint layer has a network polymer characteristic similar to that of rubber, so that the mechanical strength of the paint layer is greatly improved, and the crystallinity is further reduced after annealing treatment.

Description

Technical Field

[0001] The invention relates to the technical field of enameled wires, and in particular to a method for preparing a modified polyamide composite coating enameled wire. Background Art

[0002] Enameled wire is a wire with insulating paint coated on the surface of a metal conductor. It is mainly used for winding electromagnetic coils and has a wide range of applications in new energy vehicles, renewable energy, 5G, and the Internet of Things. The core feature of enameled wire is to achieve electrical isolation of the conductor through insulating paint, while having high requirements for mechanical strength and high temperature resistance. The types of outer paint for enameled wire mainly include polyester (PET), polyurethane (PU), polyimide (PI), and polyamide (PA), which are polymers with relatively balanced strength and high temperature resistance. The temperature resistance ranges from 130°C to 220°C, which can meet different usage scenarios. The wire inside the enameled wire is mainly copper wire. Aluminum wire or silver wire is far less than copper wire due to factors such as ductility or price.

[0003] Among the above-mentioned outer coatings for enameled wires, polyamide is the most cost-effective choice. Polyamide has a series of excellent properties such as low cost and wide source of raw materials, good processing performance, high use temperature, good mechanical properties, etc. As the outer coating of enameled wires, it can greatly improve its use temperature and strength. However, polyamide also has some defects, such as easy crystallization when stretched and poor aging resistance. These shortcomings will be further magnified on enameled wires. For example, when winding, polyamide crystallizes with high orientation in the direction of the metal wire, resulting in a decrease in strength at the outer bend. Another example is that the outer part of the wire package is exposed to ultraviolet rays and ages prematurely. Summary of the invention

[0004] In view of the above problems existing in the existing polyamide enameled wire, the present invention provides a method for preparing a modified polyamide composite coating enameled wire, comprising the following steps: 1. Preparation of modified polyamide mixed slurry The polyamine mixture is added to deionized water, sulfuric acid and acetic acid are added, and the mixture is heated to 45°C to 60°C. 0.5% to 1% of the weight of the polyamine mixture is added dropwise every 1 to 3 minutes while stirring, and the total amount added does not exceed 20% of the weight of the polyamine mixture. After reacting for 1 to 3 hours, the reactant is filtered, and the filtered material is washed and dried, and then 5% to 10% of the weight of the dried material is added with a diisocyanate and an organic tin catalyst, mixed evenly, and stored at low temperature to obtain a modified polyamide mixed slurry; 2. Sizing At room temperature, passing the enameled wire metal wire through a sizing tank filled with the modified polyamide mixed slurry obtained in step 1, so that the modified polyamide mixed slurry is evenly attached to the surface of the metal wire; 3. Finalization The sizing wire is passed through a constant temperature box at a temperature of 50°C to 80°C and then stretched by 10% to 15%; 4. Annealing Coil Heat the metal wire shaped in step 3 to 90℃~120℃, keep it warm for 10~30min, then cool it to room temperature at a rate of 1~3℃ / min, wash it with water, dry it, and then roll it up.

[0005] Furthermore, the polyamide is one of PA6, PA66, PA56 or PA610; and the number average molecular weight of the polyamide oligomer is 800-2000.

[0006] Furthermore, the polyamine mixture is a mixture of ethylenediamine and triamino compounds, wherein the mass proportion of ethylenediamine is 50% to 70%, and the triamino compound is specifically 1,3,5-phenyltriamine and / or trimethylamine.

[0007] Furthermore, the mass ratio of sulfuric acid to acetic acid is 1:(0.5-1.1), and the total amount of sulfuric acid and acetic acid is 1%-3% of the weight of the polyamine mixture.

[0008] Furthermore, the diisocyanate is one of MDI, HDI, TDI or IPDI.

[0009] Furthermore, the metal wire for the enameled wire is one of copper wire, aluminum wire or silver wire.

[0010] Compared with the prior art, the present invention has the following beneficial effects: the present invention first grafts polyamine on one end of the polyamide oligomer having a carboxyl group, so that both ends of the polyamide oligomer are amino groups, so that it can continue to react with diisocyanate, and due to the addition of triamino compounds, a certain proportion of network products will be formed, and the aging resistance will be improved. After shaping, the paint layer has a network polymer property similar to rubber, thereby greatly increasing the mechanical strength of the paint layer, and the crystallinity will be further reduced after annealing. The present invention uses a polyamine mixture and diisocyanate to modify the polyamide oligomer, which fundamentally solves the disadvantages of polyamide being easy to crystallize and age. DETAILED DESCRIPTION

[0011] The present invention is described below in conjunction with examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0012] Example 1 A method for preparing an MDI-modified PA6 composite coating enameled wire comprises the following steps: 1. Add a polyamine mixture of 60% by weight of ethylenediamine, 20% by weight of 1,3,5-phenyltriamine and 20% by weight of trimethylamine into deionized water, stir well, add sulfuric acid and acetic acid in a mass ratio of 1:1, and the total amount of sulfuric acid and acetic acid is 2% by weight of the polyamine mixture. After heating to 60°C, add 0.5% by weight of the polyamine mixture with a number average molecular weight of 800 PA6 oligomers every 1 minute while stirring, and the total amount added is 15% by weight of the polyamine mixture. After reacting for 2 hours, filter the reactant, wash and dry the filtrate, add 8% by weight of the dried product of MDI and di(dodecylthio)dibutyltin, mix well, and store at low temperature to obtain an MDI-modified PA6 mixed slurry; 2. At room temperature, pass the enameled copper wire through a sizing tank filled with the MDI-modified PA6 mixed slurry obtained in step 1, so that the modified slurry is evenly attached to the surface of the copper wire; 3. Pass the sizing copper wire through a constant temperature box at 70°C and then stretch the copper wire by 12%; 4. Heat the copper wire shaped in step 3 to 120°C, keep it warm for 20 minutes, then cool it to room temperature at a rate of 2°C / min, wash it with water, dry it, and then roll it up.

[0013] Example 2 A method for preparing an HDI-modified PA66 composite coating enameled wire comprises the following steps: 1. Add a polyamine mixture of 70% by weight of ethylenediamine and 30% by weight of trimethylamine to deionized water, stir well, add sulfuric acid and acetic acid in a mass ratio of 1:0.5, and the total amount of sulfuric acid and acetic acid is 1% by weight of the polyamine mixture. After heating to 50°C, add 0.6% by weight of the polyamine mixture with a number average molecular weight of 1000 PA66 oligomer every 2 minutes while stirring, and the total amount added is 20% by weight of the polyamine mixture. After reacting for 3 hours, filter the reactant, wash and dry the filtrate, add 10% by weight of the dried product HDI and dibutyltin dilaurate, mix well, and store at low temperature to obtain HDI modified PA66 mixed slurry; 2. At room temperature, pass the enameled copper wire through a sizing tank filled with the HDI-modified PA66 mixed slurry obtained in step 1, so that the modified slurry is evenly attached to the surface of the copper wire; 3. Pass the sizing copper wire through a constant temperature box at 60°C and then stretch the copper wire by 15%; 4. Heat the copper wire shaped in step 3 to 100°C, keep it warm for 15 minutes, then cool it to room temperature at a rate of 1.5°C / min, wash it with water, dry it, and then roll it up.

[0014] Example 3 A method for preparing a TDI-modified PA56 composite coating enameled wire comprises the following steps: 1. Add a polyamine mixture of 50% by weight of ethylenediamine, 20% by weight of 1,3,5-phenyltriamine and 30% by weight of trimethylamine to deionized water, stir well, add sulfuric acid and acetic acid in a mass ratio of 1:1.1, and the total amount of sulfuric acid and acetic acid is 3% by weight of the polyamine mixture. After heating to 45°C, add 1% by weight of the polyamine mixture with a number average molecular weight of 2000 PA56 oligomer every 3 minutes while stirring, and the total amount added is 12% by weight of the polyamine mixture. After reacting for 3 hours, filter the reactant, wash and dry the filtrate, add 5% by weight of TDI and stannous octoate of the dried product, mix well and store at low temperature to obtain TDI-modified PA56 mixed slurry; 2. At room temperature, pass the enameled aluminum wire through a sizing tank filled with the TDI-modified PA56 mixed slurry obtained in step 1, so that the modified slurry is evenly attached to the surface of the aluminum wire; 3. Pass the sizing aluminum wire through a constant temperature box at 80°C and then stretch the aluminum wire by 10%; 4. Heat the aluminum wire formed in step 3 to 90°C, keep it warm for 30 minutes, then cool it to room temperature at a rate of 1°C / min, wash it with water, dry it, and then roll it up.

[0015] Example 4 A method for preparing an IPDI-modified PA610 composite coating enameled wire comprises the following steps: 1. Add a polyamine mixture of 60% by weight of ethylenediamine, 20% by weight of 1,3,5-phenyltriamine and 20% by weight of trimethylamine to deionized water, stir well, add sulfuric acid and acetic acid in a mass ratio of 1:0.8, the total amount of sulfuric acid and acetic acid is 2.5% by weight of the polyamine mixture, heat to 50°C, keep stirring, add 1.5% by weight of the polyamine mixture of PA610 oligomers with a number average molecular weight of 1500 every 2 minutes, and the total amount added is 15% by weight of the polyamine mixture. After reacting for 2.5 hours, filter the reactant, wash and dry the filtrate, add 8% by weight of IPDI and dibutyltin dilaurate after drying, mix well and store at low temperature to obtain IPDI modified PA610 mixed slurry; 2. At room temperature, pass the silver wire of the enameled wire through a sizing tank filled with the IPDI-modified PA610 mixed slurry obtained in step 1, so that the modified slurry is evenly attached to the surface of the silver wire; 3. Pass the sizing silver wire through a constant temperature box at 75°C and then stretch the silver wire by 15%; 4. Heat the silver wire shaped in step 3 to 90°C, keep it warm for 30 minutes, then cool it to room temperature at a rate of 1°C / min, wash it with water, dry it, and then roll it up.

[0016] Comparative Examples 1 to 4 are enameled wires prepared by using the existing process using the polyamide and metal wire of Examples 1 to 4. Table 1 shows the performance test of the enameled wires of Examples 1 to 4 and Comparative Examples 1 to 4. From the data in the table, it can be seen that the modified polyamide enameled wire of the present invention has obvious improvements in tensile crystallization resistance, UV aging resistance, and mechanical strength.

[0017] Table 1. Performance test of enameled wires of Examples 1 to 4 and Comparative Examples 1 to 4 Cold drawing 10% crystallinity change T (UVA) Breaking strength Example 1 1.5%→1.9% 13.22% 357MPa Comparative Example 1 21%%→32% 29.85% 325MPa Example 2 2.3%→3.3% 12.56% 346MPa Comparative Example 2 55%→73% 34.68% 318MPa Example 3 4.8%→6.6% 13.11% 231MPa Comparative Example 3 62%→78% 28.36% 208MPa Example 4 2.5%→3.1% 12.95% 384MPa Comparative Example 4 38%→52% 26.74% 351MPa Note: 1. The diameter of the metal wire is 1mm; 2. The anti-ultraviolet performance test standard is GB / T188302009.

[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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a modified polyamide composite coated enameled wire, characterized in that: The following steps are involved:

1. Preparation of modified polyamide mixed slurry The polyamine mixture is added to deionized water, sulfuric acid and acetic acid are added, and the mixture is heated to 45°C to 60°C. 0.5% to 1% of the weight of the polyamine mixture of polyamide oligomer is added dropwise every 1 to 3 minutes while stirring, and the total amount added does not exceed 20% of the weight of the polyamine mixture. After reacting for 1 to 3 hours, the reactant is filtered, the filtrate is washed and dried, and 5% to 10% of the weight of the dried product of diisocyanate and organic tin catalyst are added, mixed evenly, and stored at low temperature to obtain a modified polyamide mixed slurry; 2. Sizing At room temperature, passing the enameled wire metal wire through a sizing tank filled with the modified polyamide mixed slurry obtained in step 1, so that the modified polyamide mixed slurry is evenly attached to the surface of the metal wire; 3. Finalization The sizing wire is passed through a constant temperature box at a temperature of 50°C to 80°C and then stretched by 10% to 15%; 4. Annealing Coil Heat the metal wire shaped in step 3 to 90°C~120°C, keep it warm for 10~30 minutes, then cool it to room temperature at a rate of 1~3°C / min, wash it with water, dry it, and then roll it up.

2. The method for preparing the modified polyamide composite coated enameled wire according to claim 1, characterized in that: In step 1, the polyamide is one of PA6, PA66, PA56 or PA610.

3. The method for preparing the modified polyamide composite coated enameled wire according to claim 2, characterized in that: The number average molecular weight of the polyamide oligomer is 800-2000.

4. The method for preparing the modified polyamide composite coating enameled wire according to claim 2, characterized in that: In step 1, the polyamine mixture is a mixture of ethylenediamine and triamino compounds, wherein the mass proportion of ethylenediamine is 50% to 70%.

5. The method for preparing the modified polyamide composite coated enameled wire according to claim 2, characterized in that: In step 1, the mass ratio of sulfuric acid to acetic acid is 1:(0.5-1.1), and the total amount of sulfuric acid and acetic acid is 1%-3% of the weight of the polyamine mixture.

6. The method for preparing the modified polyamide composite coating enameled wire according to claim 2, characterized in that: In step 1, the diisocyanate is one of MDI, HDI, TDI or IPDI.

7. The method for preparing the modified polyamide composite coating enameled wire according to claim 1, characterized in that: The metal wire for the enameled wire is one of copper wire, aluminum wire or silver wire.