INSULATED WIRE AND PREPARATION METHOD THEREOF, COIL AND ELECTRONIC/ELECTRICAL DEVICE

Abstract

The present application discloses an insulated wire and a preparation method thereof, a coil and an electronic/electrical device. According to the insulated wire, a bonding layer containing PEEK nano-powder is arranged between a conductor and a PEEK resin insulating layer, and a bonding agent for forming the bonding layer contains organic solvent, polyamide-imide resin and PEEK nano-powder material which are mixed. The bonding layer can be well bonded with both the conductor material and the PEEK resin insulating layer, so that the produced insulated wire rod has good adhesion, and cracking and detachment will not appear during application.

Claims

1. An insulated wire, comprising a conductor, and a bonding layer and a PEEK resin insulating layer arranged outside the conductor in turn, the bonding layer is located between the conductor and the PEEK resin insulating layer; the PEEK resin insulating layer is made of a PEEK resin material; and the bonding layer is formed by curing a bonding agent, which comprises organic solvent, polyamide-imide resin and PEEK nano-powder material which are mixed.

2. The insulated wire of claim 1, wherein the bonding layer has a thickness of 5-30 μm, further preferably 10-20 μm.

3. The insulated wire of claim 1, wherein the bonding agent comprises, based on parts by weight, 50-80 parts of organic solvent, 20-30 parts of polyamide-imide resin and 2-8 parts of PEEK nano-powder material; preferably, the bonding agent has a solid content of 20-40%, and a viscosity at 30° C. of 2,500-3,500 cp, and preferably 3,000 cp.

4. The insulated wire of claim 1, wherein the bonding agent also comprises a dispersant, which accounts for 1-3% by weight in the bonding agent; and preferably, the dispersant is selected from one or more of cetyltrimethylammonium bromide, alkylphenol ethylene oxide condensate emulsifier, sodium dodecyl sulfate, sodium dodecyl sulfonate and sodium dodecylbenzene sulfonate.

5. The insulated wire of claim 1, wherein the organic solvent comprises nitrogen-containing polar solvent, ether-based solvent, xylene or a mixture thereof; preferably, the nitrogen-containing polar solvent is selected from one or more of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea and dimethylethyleneurea; and preferably, the ether-based solvent is selected from one or more of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol and triethylene glycol.

6. The insulated wire of claim 1, wherein the polyamide-imide resin is amorphous resin with a glass transition temperature between 200° C. and 300° C.; and preferably, the polyamide-imide resin has an elastic modulus of 100-1,000 MPa, and preferably 300-800 MPa.

7. The insulated wire of claim 1, wherein the PEEK resin material has a glass transition temperature of 320-360° C., and a melt viscosity at 400° C. of 120-140 pa.Math.s, and preferably 130 pa.Math.s.

8. The insulated wire of claim 1, wherein the PEEK resin insulating layer has a thickness of 10-1,000 μm, preferably 25-750 μm, in particular preferably 30-500 μm, and especially 50-250 μm.

9. The insulated wire of claim 1, wherein the PEEK nano-powder material has a particle size of 50-100 nm.

10. The insulated wire of claim 1, wherein the conductor is a bare conductor, the bonding agent is applied to the surface of the conductor to form the bonding layer covering the bare conductor.

11. The insulated wire of claim 1, wherein the conductor is a bare conductor; a PAI primer layer is formed on the surface of the bare conductor; and the bonding agent is applied to the PAI primer layer to form the bonding layer covering the conductor.

12. The insulated wire of claim 1, wherein the conductor has a cross-section as a circle, a rectangle, or a rectangle with rounded corners; and preferably, the conductor is made of copper, aluminum or an alloy thereof.

13. A coil, comprising the insulated wire of claim 1.

14. An electronic/electrical device, comprising the coil of claim 13.

15. A method for preparing an insulated wire, comprising: step 1, applying a bonding agent to a surface of a conductor to form a bonding layer covering the conductor and obtain a core wire; and step 2, extruding a PEEK resin material outside the bonding layer of the core wire to form a PEEK resin insulating layer and obtain an insulated wire.

16. The method for preparing an insulated wire of claim 15, before step 2, further comprising: preheating the core wire at a temperature of higher than 400° C.; wherein step 2 further comprises: heating the PEEK resin material to a molten state; with the rotation of a screw of a screw extruder, coating the surface of the core wire with the PEEK resin material evenly; and forming the PEEK resin insulating layer after cooling and crystallization.

17. The method for preparing an insulated wire of claim 15, wherein in step 1, the bonding agent is prepared by the following steps: dissolving polyamide-imide resin in the organic solvent, and heating and stirring the solution; and adding the PEEK nano-powder material and dissolving the solution under stirring to obtain the bonding agent;

18. The method for preparing an insulated wire of claim 17, after the step of adding the PEEK nano-powder material and dissolving the solution under stirring, further comprising: adding the organic solvent, and preferably, a mixture of N-methylpyrrolidone and xylene to adjust the solid content and viscosity; preferably, adding the dispersant, wherein preferably, the dispersant is selected from one or more of cetyltrimethylammonium bromide, an alkylphenol ethylene oxide condensate emulsifier, sodium dodecyl sulfate, sodium dodecyl sulfonate and sodium dodecylbenzene sulfonate.

19. The method for preparing an insulated wire of claim 17, wherein the bonding agent comprises, based on parts by weight, 50-80 parts of organic solvent, 20-30 parts of polyamide-imide resin and 2-8 parts of PEEK nano-powder material;

20. The method for preparing an insulated wire of claim 17, wherein the organic solvent comprises nitrogen-containing polar solvent, ether-based solvent, xylene or a mixture thereof; preferably, the nitrogen-containing polar solvent is specifically selected from one or more of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea and dimethylethyleneurea; and preferably, the ether-based solvent is specifically selected from one or more of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol and triethylene glycol;

21. The method for preparing an insulated wire of claim 17, wherein the polyamide-imide resin is amorphous resin with a glass transition temperature between 200° C. and 300° C.; and preferably, the polyamide-imide resin has an elastic modulus of 100-1,000 MPa, and preferably 300-800 MPa.

22. An insulated wire, obtained by the method for preparing an insulated wire of claim 15.

23. An electronic/electrical device, comprising the insulated wire of claim 22.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0031] FIG. 1 is a sectional structural view of an insulated wire of the present application.

[0032] FIG. 2 is a flow chart of a method for preparing an insulated wire of the present application.

[0033] FIG. 3 is a schematic diagram of a U-bending test on the insulated wire in examples and a comparative example of the present application.

[0034] FIG. 4 is a schematic diagram of a winding test on the insulated wire in examples and a comparative example of the present application.

DESCRIPTION OF EMBODIMENTS

[0035] The technical solution of the present application will be further described in detail below in conjunction with specific embodiments. The following embodiments are intended to illustrate and explain the present application only, and should not be interpreted as a limitation to the protection scope of the present application. All technologies realized on the basis of the aforesaid contents of the present application fall within the protection scope of the present application.

[0036] Referring to FIGS. 1-2, a method for preparing the insulated wire of the present application specifically includes the following steps:

[0037] step 1, a bonding agent is applied outside a bare conductor 1 by an enameling machine, during which an organic solvent in the bonding agent volatilizes, and the bonding agent is cured to form a bonding layer 2 covering the bare conductor 1 and obtain a core wire; then, before entering a head of a screw extruder, the core wire is preheated at a temperature of higher than 400° C., during which the organic solvent in the bonding agent further volatilizes;

[0038] wherein, the bonding agent is prepared specifically as follows: dissolving polyamide-imide resin in the organic solvent, and heating and stirring the solution; adding PEEK nano-powder material and fully dissolving the solution under stirring; and adding the organic solvent to adjust the solid content and viscosity to obtain the bonding agent.

[0039] step 2, a polyetheretherketone (PEEK) resin material is added to a barrel of the screw extruder and heated to a molten state at 380-410° C.; then, with the rotation of a screw of the screw extruder, the PEEK resin material flows uniformly inside the barrel; the preheated core wire is placed in front of the head of the screw extruder, and the surface of the core wire is coated with the PEEK resin material evenly through molds of different specifications at the head, and a PEEK resin insulating layer 3 is formed after cooling and crystallization to obtain the insulated wire with a structure as shown in FIG. 1.

[0040] [Bare Conductor]

[0041] The bare conductor 1 of the present application may have a cross-section as a circle or a rectangle, including a rectangle with rounded corners, and is made of copper, aluminum and their alloys. For welding considerations, a low-oxygen copper or oxygen-free copper conductor with an oxygen content of less than 30 ppm is preferable.

[0042] [Bonding Layer]

[0043] The bonding layer 2 of the present application may be directly applied to the bare conductor 1. A PAI primer layer may be arranged on the bare conductor 1 by applying PAI varnish to the conductor and baking the varnish. But in consideration of the cost, more preferably, the bonding layer is directly applied to the surface of the conductor, without the need of separately arranging the PAI primer layer. The bonding layer is mainly made of PAI resin, which can achieve common layer insulation in the prior art, without the need of forming the separate PAI primer layer through baking on the surface layer of the bare conductor.

[0044] The bonding agent includes organic solvent, polyamide-imide (PAI) resin and PEEK nano-powder material; the bonding agent includes, based on parts by weight, 50-80 parts of organic solvent, 20-30 parts of polyamide-imide resin and 2-8 parts of PEEK nano-powder material.

[0045] For selection of the organic solvent, types that can dissolve PAI resin and well disperse PEEK nano-powder in a PAI resin matrix are taken into consideration, including nitrogen-containing polar solvent, ether-based solvent, xylene or a mixture thereof, wherein the nitrogen-containing polar solvent is specifically selected from one or more of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea and dimethylethyleneurea; the ether-based solvent is specifically selected from one or more of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol and triethylene glycol.

[0046] A dispersant may also be added to well disperse the PEEK nano-powder material in the organic solvent. The dispersant is a surfactant commonly used in the field, and further preferably selected from one or more of cetyltrimethylammonium bromide, alkylphenol ethylene oxide condensate emulsifier, sodium dodecyl sulfate, sodium dodecyl sulfonate and sodium dodecylbenzene sulfonate.

[0047] For selection of PAI resin, considering the replacement of the primer layer with the bonding layer, in order to obtain good tensile and bending properties, PAI is preferably amorphous resin with a glass transition temperature between 200° C. and 300° C. If the glass transition temperature is too low, the electrical properties may be degraded in a heat resistance test. If the glass transition temperature is too high, residues will be possibly left due to incomplete melting during welding, thereby reducing the weldability. An elastic modulus of 100-1,000 MPa, and preferably 300-800 MPa, provides good mechanical strength and bending properties.

[0048] The bonding layer 2 has a thickness between 5 μm and 30 μm, and further preferably between 10 μm and 20 μm. If the bonding layer 2 is too thin, its adhesion to the bare conductor and the PEEK insulating layer is insufficient. If the bonding layer 2 is too thick, the wire is difficult to bend in a bending process.

[0049] Table 1 shows comparative experiment data of different bonding layer thicknesses vs adhesion. It can be seen from a comparative experiment described below that all test results are recorded as “Pass” when the thickness of the bonding layer 2 of the insulated wire of the present application is between 5 μm and 30 μm, and the adhesion-losing length is short, indicating that the adhesion of the bonding layer is excellent. The adhesion-losing length is herein defined as the length of an insulating film losing adhesion, starting from a notch. The smaller the length value, the better the adhesion of the bonding layer.

TABLE-US-00001 TABLE 1 Performance tests of different bonding layer for insulated wires Bonding layer verification plan Test result Bonding PEEK Adhesion- PAI layer layer layer losing U-bending Winding Plan Conductor thickness thickness thickness length test test Instance TU1 oxygen-free N/A N/A 100 μm 3.20 mm Fail Fail 1 copper Instance TU1 oxygen-free N/A  5 μm 100 μm 1.85 mm Pass Pass 2 copper Instance TU1 oxygen-free N/A 10 μm 100 μm 1.30 mm Pass Pass 3 copper Instance TU1 oxygen-free N/A 15 μm 100 μm 0.90 mm Pass Pass 4 copper Instance TU1 oxygen-free N/A 15 μm 100 μm 1.97 mm Pass Pass 5 copper (bonding layer + 5 g of surfactant) Instance TU1 oxygen-free N/A 20 μm 100 μm 1.45 mm Pass Pass 6 copper Instance TU1 oxygen-free N/A 20 μm 100 μm 15.0 mm Fail Fail 7 copper (no PEEK nano- powder particles added) Instance TU1 oxygen-free N/A 25 μm 100 μm 1.50 mm Pass Pass 8 copper Instance TU1 oxygen-free N/A 30 μm 100 μm 1.75 mm Pass Pass 9 copper Instance TU1 oxygen-free N/A 35 μm 100 μm 1.65 mm Pass Pass 10 copper Instance TU1 oxygen-free N/A 10 μm 200 μm 1.67 mm Pass Pass 11 copper Instance TU1 oxygen-free N/A 15 μm 200 μm 1.30 mm Pass Pass 12 copper Instance TU1 oxygen-free N/A 20 μm 200 μm 1.50 mm Pass Pass 13 copper

[0050] The PEEK nano-powder of the present application can be prepared by common methods in the prior art, such as cryopulverization, sol-gel and dissolution-precipitation, with an average particle size of 50-100 nm. The PEEK nano-powder used in the present application is commercially available.

[0051] [PEEK Resin Insulating Layer]

[0052] Based on considerations of the insulation and extrusion properties, the PEEK resin material has a glass transition temperature of 320-360° C., and a melt viscosity at 400° C. of 120-140 pa.Math.s, and preferably 130 pa.Math.s; the PEEK resin material has favorable melt extrusion effects, and balanced mechanical properties and machinability within this melt viscosity range. PEEK resin insulating layers with glass transition temperatures and melt indexes satisfying different conditions can be obtained by regulating molecular weights and modifying a resin system. The PEEK resin insulating layer has a thickness of 10-1,000 μm, preferably 25-750 μm, in particular preferably 30-500 μm, and especially 50-250 μm.

[0053] The implementation process of the present application will be illustrated below through the specific embodiments, and implementation effects are fully evaluated. Unless otherwise stated, all raw materials and reagents used in these embodiments are commercially available or can be prepared by known methods.

EXAMPLE 1: PREPARATION OF INSULATED WIRE

Preparation of Bonding Agent

[0054] 25 g of modified polyamide-imide resin was dissolved in 50 ml of N-methylpyrrolidone (NMP) and xylene (V/V 1/1) mixed solution, the solution was heated and stirred, then 5 g of PEEK nano-powder material with an average particle size of 50-100 nm was added and fully dissolved under stirring, and 25 ml of N-methylpyrrolidone and xylene mixed solution was added to adjust the solid content and viscosity.

Application of Bonding Layer

[0055] The bonding agent was applied to a bare flat copper conductor to a thickness of 15 μm by an enameling machine, during which an organic solvent in the bonding agent volatilized, the bonding agent was cured to form a bonding layer and obtain a core wire, and then the core wire was preheated to 400° C.

Formation of PEEK Resin Insulating Layer Through Extrusion

[0056] A PEEK resin material with a glass transition temperature of 340° C. was provided. The PEEK resin material was added to a barrel of a screw extruder and heated to 380° C. in a molten state. Then, with the rotation of a screw of the screw extruder, the PEEK resin material flowed uniformly inside the barrel. The preheated core wire was placed in front of a head of the screw extruder, the surface of the core wire was coated with the PEEK resin material evenly through molds at the head, and a 100 μm-thick PEEK resin insulating layer was formed after cooling and crystallization to obtain a flat insulated wire.

EXAMPLE 2: PREPARATION OF INSULATED WIRE

[0057] Compared with example 1, before the bonding layer was formed through application, a 10 μm PAI primer layer was formed on the bare copper conductor. Other technical features are the same as those in example 1, and will not be repeated here.

EXAMPLE 3: PREPARATION OF INSULATED WIRE

[0058] Compared with example 1, 5 g of cetyltrimethylammonium bromide as a surfactant was also added to the prepared bonding agent. Other technical features are the same as those in example 1, and will not be repeated here.

EXAMPLE 4: PREPARATION OF INSULATED WIRE

[0059] Compared with example 1, the thickness of the bonding layer was 25 μm. Other technical features are the same as those in example 1, and will not be repeated here.

EXAMPLE 5: PREPARATION OF INSULATED WIRE

[0060] Compared with example 1, the thickness of the PEEK resin insulating layer was 200 μm. Other technical features are the same as those in example 1, and will not be repeated here.

COMPARATIVE EXAMPLE 1

[0061] A bare copper conductor was directly coated with a 100 μm-thick PEEK resin insulating layer through melt extrusion to obtain a comparative wire.

Experimental Example: Characterization and testing

1. Adhesion Test

[0062] 300 mm of insulated wires obtained in examples 1-5 and comparative example 1 were taken as samples respectively. The samples were placed between two clamps and kept on the same axis as the clamps, with both ends clamped; the samples were stretched by 20% at a rate of 300 mm/min, and checked for the adhesion-losing length of films. For this test method, the adhesion of the films is excellent if the adhesion-losing length is less than 2 mm.

2. Bending Machinability Test

[0063] A U-bending test and a winding test were conducted for the insulated wires of examples 1-5 and comparative example 1 respectively by the following methods.

[0064] U-bend test: As shown in FIG. 3, two 500 mm-long straight insulated wires were bended by 180±2° around a polished test spindle. One was flat-wise wound (spindle diameter=2 times the wire thickness), and the other was edgewise wound (spindle diameter=2 times the wire width). In FIG. 3, “B” and “D” represent the width and thickness of the insulated wires respectively.

[0065] In this test, after flat-wise winding and edgewise winding, products having smooth surfaces without cracks were recorded as “Pass”, while those having cracked surfaces were recorded as “Fail”.

[0066] Winding test: As shown in FIG. 4, two 500 mm-long straight insulated wires were wound by 6 turns around a polished test spindle. One was flat-wise wound (spindle diameter=2 times the wire thickness), and the other was edgewise wound (spindle diameter=2 times the wire width). Individual coils should be wound closely in contact with each other, with a maximum clearance of ≤2 mm.

[0067] In this test, after flat-wise winding and edgewise winding, products having smooth surfaces without cracks were recorded as “Pass”, while those having cracked surfaces were recorded as “Fail”.

TABLE-US-00002 TABLE 2 Performance tests of insulated wires Adhesion-losing length U-bending test Winding test Example 1 <2 mm Pass Pass Example 2 <2 mm Pass Pass Example 3 <2 mm Pass Pass Example 4 <2 mm Pass Pass Example 5 <2 mm Pass Pass Comparative >2 mm Fail Fail Example 1

[0068] These examples and test results show that the insulated wire of the present application has favorable machinability, and excellent adhesion between insulating layers, and can effectively solve the problems of detachment during stretching and cracking during winding.

[0069] The present application has the following beneficial effects:

[0070] The present application provides an insulated wire; the bonding layer containing PEEK nano-powder is arranged between the conductor and the PEEK resin insulating layer, and the bonding agent for forming the bonding layer contains organic solvent, polyamide-imide resin and PEEK nano-powder material which are mixed. The bonding layer can be well bonded with both the bare conductor material and the PEEK resin insulating layer, so that the produced insulated wire rod has good adhesion; in addition, after adhesion and curing, the bonding layer is mainly made of PAI resin, which can achieve common layer insulation in the prior art, without the need of forming a separate PAI primer layer through baking on the surface layer of the bare conductor.

[0071] Though the present application is described in detail by means of these examples, the foregoing are only for those skilled in the art to understand the present application more easily, rather than limiting the implementation scope of the present application. Therefore, all equivalent changes and modifications made according to the shape and structure features and the spirit of claims of the present application still fall within the scope of the present application.