CN115424770A - High-voltage load wire - Google Patents

High-voltage load wire Download PDF

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Publication number
CN115424770A
CN115424770A CN202211049351.2A CN202211049351A CN115424770A CN 115424770 A CN115424770 A CN 115424770A CN 202211049351 A CN202211049351 A CN 202211049351A CN 115424770 A CN115424770 A CN 115424770A
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varnish
surge
voltage load
silica
layer
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尹勇
高翔
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Jiangxi Zhujing New Materials Co ltd
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Jiangxi Zhujing New Materials Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/04—Flexible cables, conductors, or cords, e.g. trailing cables
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D179/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen, with or without oxygen, or carbon only, not provided for in groups C09D161/00 - C09D177/00
    • C09D179/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C09D179/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/011—Nanostructured additives

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  • Engineering & Computer Science (AREA)
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Abstract

The invention discloses a high-voltage load wire. The high-voltage load wire comprises a conductor, and a double-layer structure of a high-adhesion layer and a surge-resistant layer, wherein the high-adhesion layer is positioned near the conductor, and the double-layer structure comprises the high-adhesion layer covering the periphery of the conductor and the surge-resistant layer positioned on the surface of the high-adhesion layer. As the amount of silica used increases, the surge resistance of the high-voltage load wire improves, and at the same time, the flexibility of the high-voltage load wire does not significantly deteriorate. The high-voltage load wire of the present invention thus achieves both excellent flexibility and surge resistance.

Description

High-voltage load wire
Technical Field
The invention relates to the field of electric wires, in particular to a high-voltage load electric wire.
Background
Since the EV, PHEV, and HEV motors mounted in the environment-compatible vehicles are often used in a high-temperature state while applying a very high voltage, a non-discharge design in which partial discharge does not occur at a high temperature is important. However, the no-discharge design requires accurate design of the surge (surge) voltage generated in the inverter (inverter) and the motor and also assumes the worst case for the vehicle running environment, and therefore the difficulty in designing the insulating film is extremely high.
According to the above problems, a wire insulation coating (enamel) is mixed with SiO while allowing discharge 2 (silicon dioxide), and surge-resistant (corona-resistant) wires that reduce damage to the insulating film due to the electrical discharge that occurs. In the surge-resistant wire, as described above, siO is mixed into the insulating film 2 However, this causes deterioration in the flexibility of the film, and the film breaks in the wire processing, resulting in a significant decrease in the insulation properties.
As a method for improving the flexibility of the film, the following measures have been studied: as a countermeasure, an uppermost surface of the wire is covered with an insulating film having excellent elongation, but the wire in this case does not have a surge resistant layer and the V-t characteristics deteriorate accordingly. Second countermeasure is to reduce SiO mixed into the inside of the insulating coating 2 The amount used, however, also results in deterioration of V-t characteristics. The present invention is directed to solving an important technical problem of finding an insulating film composition that can achieve both flexibility and surge resistance.
Disclosure of Invention
In view of the above problems, the present invention provides a high-voltage load wire. The high-voltage load wire uses a material such as polyimide, which is difficult to reduce even if the amount of silica used is increased, and controls the uniform dispersion of silica in the surge-resistant layer. It was unexpectedly found in experiments that the surge resistance of the high-voltage load electric wire was improved with an increase in the amount of silica used, and at the same time, the flexibility of the high-voltage load electric wire was not significantly deteriorated. The high-voltage load wire of the present invention thus achieves both excellent flexibility and surge resistance.
The high-voltage load wire includes a conductor and a double-layer structure of a high-adhesion layer and a surge-resistant layer located in the vicinity of the conductor. The double-layer structure comprises a high-adhesion layer covering the periphery of the conductor and a surge-resistant layer positioned on the surface of the high-adhesion layer.
Preferably, the high-adhesion layer varnish for forming the high-adhesion layer includes one of a polyester imide varnish (EI), a polyamide imide varnish (AI), a polyimide varnish (PI), a polyamide varnish, a polyvinyl formal varnish, a polyurethane varnish, and a polyester varnish.
Preferably, the thickness of the high adhesion layer is 1 to 10 μm.
Preferably, the surge-resistant layer varnish for forming the surge-resistant layer includes a base varnish and 15 to 35phr of silica with respect to the base varnish. Preferably, the silica comprises 20 to 35phr of the base varnish.
Preferably, the size of the silicon dioxide is 10-30nm.
Preferably, the thickness of the surge-resistant layer is 50-55 μm.
Preferably, the high-voltage load wire does not include an insulating coating layer disposed on the surge-resistant layer surface.
Preferably, the high-voltage load wire has a V-t failure time of 400 hours or more, preferably 700 hours or more.
Drawings
FIG. 1 is a diagram comparing a conventional countermeasure with the technical solution of the present invention;
FIG. 2 is a graph showing an evaluation test of V-t time;
FIG. 3 is a view showing an evaluation test of flexibility;
FIG. 4 is a structural view of an insulated wire of comparative example 1;
FIG. 5 is a view showing the structure of an insulated wire of comparative example 2;
FIG. 6 is a structural view of an insulated wire of comparative example 3;
FIG. 7 is a structural view of an insulated wire of comparative example 4;
FIG. 8 is a structural view of an insulated wire according to examples 1 to 8;
FIG. 9 is a schematic diagram showing the presence of local defects caused by the introduction of silica having a large particle size, and is a schematic diagram showing the uniform dispersion of the nano-sized silica of the present invention in a varnish for a surge-resistant layer;
FIG. 10 is a left side view of the scanning electron microscope of comparative example 1, and a right side view of the scanning electron microscope of example 3.
Detailed Description
The present invention is further illustrated by the following examples, which are to be understood as merely illustrative of, and not restrictive on, the present invention. The high-voltage load electric wire according to the present invention is exemplarily described below.
The high-voltage load wire includes a conductor and a double-layer structure of a high-adhesion layer and a surge-resistant layer located in the vicinity of the conductor. Specifically, a high adhesion layer covering the outer periphery of the conductor and a surge-resistant layer located on the surface of the high adhesion layer.
The size and shape of the conductors can be adapted as desired. For example, the cross-sectional shape of the conductor may be a prolate rectangle. The material of the conductor includes, but is not limited to, elemental copper, elemental aluminum, and the like.
The high adhesion layer functions to maintain close contact with the conductor. The varnish for the high-adhesion layer includes, but is not limited to, polyester imide varnish (EI), polyamide imide varnish (AI), polyimide varnish (PI), polyamide varnish, polyvinyl formal varnish, polyurethane varnish, polyester varnish, and the like. The source of the varnish for the high adhesion layer is not limited, and the varnish can be purchased from commercial sources or obtained in a self-made manner. In some embodiments, the solid content of the varnish for high adhesion layer is 10 to 30wt%. When the varnish solid content is too low, the coating of the film is reduced (the film cannot be uniformly coated), and as a result, the V-t life is deteriorated. When the solid content of the varnish is too high, the life of the varnish may be deteriorated, and curing (gelation) of the varnish may be caused, and therefore, 10 to 30wt% is preferable.
In some embodiments, the high adhesion layer has a thickness of 1 to 10 μm. As an example, the thickness of the high adhesion layer is 5 μm. The thinner the high-adhesion layer is, the thicker the surge-resistant layer is, and hence the V-t characteristics (product life) are facilitated. However, since the electric wire is manufactured by the coating → baking process, it is difficult to make it extremely thin, and thus a range of 1 to 10 μm is set from an appropriate value of the number of coatings and the coating gap.
The varnish for the surge-resistant layer comprises a base varnish and 15 to 35phr of silica based on the base varnish. If the proportion of silica in the base varnish is less than 15phr, the V-t breakdown time of the surge-resistant layer decreases, making it difficult to meet the application requirements. If the proportion of silica in the base varnish is more than 35phr, flexibility is deteriorated and the film may be broken during processing. Preferably, the silica comprises 20 to 35phr of the base varnish.
The prior art uses silica in a varnish for a surge-resistant layer, which is generally 1 to 10 μm in size and the micron-sized silica content is generally around 10phr, and thus, although the uniform dispersion of the micron-sized silica particles can be maintained, the surge-resistant performance of the electric wire is lowered. Further increasing the amount of the micron-sized silica improves the surge resistance of the wire, but the flexibility is reduced by stress concentration due to the non-uniform particle size of the silica. Thus, when silica having a large particle size is introduced, defects may be locally generated (SiO may not be locally present) 2 The region) of the power supply, the surge resistance is unstable.
The prior art has the problem that the silica particle size is too large or the silica is too aggregated, which makes it necessary to obtain an excellent silica dispersion state. I.e., in the surge resistance (V-t life), siO 2 The dispersion state of (a) is extremely important. According to the invention, the size of the silicon dioxide in the varnish for the surge-resistant layer is optimized, and the nano-scale silicon dioxide of 10-30nm is uniformly dispersed in the varnish for the surge-resistant layer, so that the usage amount of the silicon dioxide in the surge-resistant layer is obviously increased, and the surge-resistant performance is improved while the flexibility of the electric wire is maintained.
Specifically, the inorganic filler silica is reduced in size to a nano size to prevent the aggregated form of these fillers from being uniformly dispersed, thereby improving the stress concentration phenomenon due to the uneven distribution of silica. The use of colloidal silica can overcome the above problems. The polyimide varnish according to some embodiments is obtained by dispersing nano silica surface-modified with a triazine silane coupling agent in a polyimide precursor solution. The triazine silane coupling agent is a silane coupling agent having a triazine structure in a molecule.
The polyimide precursor solution contains a polyimide precursor and a solvent. The solvent is not particularly limited, and may be an organic solvent, and may be at least one selected from the group consisting of N, N-dimethylacetamide, N-dimethylformamide, N-methylpyrrolidone, and xylene.
Polyimide precursors include any polyimide precursor material derived from diamine and dianhydride monomers and capable of being converted to polyimide, such as polyamic acids and the like.
The diamine is preferably an aromatic diamine, and examples thereof include phenylenediamine (PPD), diaminodiphenyl ether (ODA), 4,4 '-diamino-2,2' -dimethylbiphenyl, 4,4 '-diamino-3,3' -dimethylbiphenyl, bis (4-aminophenyl) sulfide, 3,3 '-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) ] phenyl ] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl ] propane, 4,4' -bis (4-aminophenoxy) biphenyl, 4943-bis (3543-aminophenoxy) benzene, and bis (3524-trifluoromethylbiphenyl). These diamines may be used alone or in combination of two or more.
The dianhydride is preferably an aromatic dianhydride, and examples thereof include pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4' -benzophenonetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3',4,4' -diphenylsulfonetetracarboxylic dianhydride, 4,4'- (hexafluoroisopropylidene) diphthalic anhydride, 4,4' - (4,4 '-isopropylidenediphenoxy) diphthalic anhydride, 4,4' -oxydiphthalic anhydride, bis (1,3-dioxo-5272-dihydrozzff 5272) -5-carboxybenzofurane-7945-phenylene-7945. These dianhydrides may be used singly or in combination of two or more.
Colloidal nanosilica (or called colloidal silica, organosilicone) refers to a colloid in which nano-sized silica (or called nano-silica) has been dispersed in a solvent.
In the present embodiment, colloidal nanosilica is used, and the affinity between the nanosilica and the polyimide precursor can be improved by surface-treating the nanosilica with a silane coupling agent, and the silica particles can maintain the original particle diameter after the colloidal nanosilica and the polyimide precursor are mixed and after the polyimide varnish is formed into a film as described below. That is, the silica in the resulting polyimide varnish was dispersed in a nano size. Thus, light is not scattered, and the polyimide varnish is transparent. Further, the polyimide varnish had good storage stability. The coating film of the polyimide varnish has good toughness. If the nano silica powder is used as it is, it is agglomerated into secondary, tertiary, and quaternary particles, and it is difficult to break the particles by means of ultrasound or the like. The polyimide varnish thus obtained was very cloudy and had poor toughness of the coating film. The silane coupling agent used is a triazine-based silane coupling agent, and adhesion and abrasion resistance between the polyimide film and the conductor can be improved as compared with the case where a general silane coupling agent such as 3-aminopropyltriethoxysilane is used. The reason for this may be that the N atom in the triazine skeleton may form a coordinate bond with a conductor such as a copper conductor.
The nano-sized silica in the colloidal nanosilica has a size of the order of nanometers in at least one dimension, and preferably has a size of the order of nanometers in each dimension. In a preferred embodiment, the nanosilica has a size in at least one dimension of 5 to 100nm. This makes it possible to impart surge resistance without impairing the toughness of the resulting coating film.
The solvent in the colloidal nanosilica is an organic solvent, and may be, for example, at least one selected from the group consisting of N, N-dimethylacetamide, N-dimethylformamide, N-methylpyrrolidone, and xylene.
The concentration of silica in the colloidal nanosilica may be from 5 to 40wt%. Colloidal silica can be prepared on its own or purchased.
The base resin varnish of the surge-resistant layer varnish is a polyimide varnish, which is advantageous in improving flexibility. In some embodiments, the solid content of the polyimide varnish for surge resistance layer is 20 to 30wt%. When the solid content of the polyimide varnish for surge resistant layer is too low, the coating of the polyimide varnish for surge resistant layer is reduced (the coating cannot be uniformly coated), and as a result, the V-t life is deteriorated. When the solid content of the surge-resistant varnish is too high, the life of the varnish may be deteriorated, and the varnish may be cured (gelled), and therefore, 20 to 30wt% is preferable. Wherein the polyimide resin may have a weight average molecular weight of 10,000 to 100,000. The weight average molecular weight of the polyimide resin is more than 100,000, which causes the viscosity of the varnish to be excessively high and the workability to be deteriorated. The polyimide resin having a weight average molecular weight of less than 10,000 causes a decrease in the toughness of the film.
The diamine of the polyimide varnish used in the embodiment is ODA, and the dianhydride is PMDA and/or BPDA. The diamine and dianhydride are selected for use because they have a modified structure, and can improve hydrolysis resistance. The ratio of PMDA to BPDA can be adapted as desired. The molar ratio of the diamine and the dianhydride is preferably an equimolar ratio for improved flexibility.
The thickness of the surge-resistant layer is 50-55 μm. The surge-resistant layer has a thickness of 55 μm, for example. The surge-proof performance is improved if the thickness of the surge-proof layer is increased, but the thickness is selected so that the V-t lifetime can be maintained as much as possible by the thin film because the conductor occupancy (occupancy) in the slot (slot) is decreased.
Preferably, the ratio of the thickness of the surge-resistant layer to the thickness of the high-adhesion layer is 5:1 to 55:1. the thickness ratio of the surge-resistant layer to the high-adhesion layer in the embodiment is 11.
A thermoplastic may be added to the varnish as needed. Thermoplastic agents include, but are not limited to, PPS, PEEK, PTFE, PFA. The amount of thermoplastic added is 0.1 to 50phr of the varnish.
The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that insubstantial modifications and adaptations of the invention by those skilled in the art based on the foregoing description are intended to be included within the scope of the invention. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.
The PMDA (1,2,4,5-pyromellitic dianhydride) used in the following examples and comparative examples was purchased from Tokyo chemical industry Co., ltd, the ODA was purchased from Tokyo chemical industry Co., ltd, and the BPDA was purchased from Tokyo chemical industry Co., ltd.
Preparation of the varnish
A PI varnish was prepared under the commercial name Ulmide-D28. ODA was dissolved in NMP and stirred for 1 hour, then PMDA was added, keeping the molar ratio of PMDA to ODA at 100, and stirring was continued for 5 hours to give PI varnish with a solids content of 28 wt%.
Prepare PI varnish of BPDA70/PMDA30/ODA 100. ODA was dissolved in NMP and stirred for 1 hour, then BPDA and PMDA were added, maintaining BPDA: and (3) PMDA: the molar ratio of ODA was 70:30: stirring was continued for 5 hours at 100 to give a PI varnish having a solids content of 28% by weight.
Comparative example 1
Preparing an electric wire: and drawing the conductor with the diameter of 8mm to the diameter of 4-5mm by using a drawing die. The wire drawing die is in the shape of a flat angle with the thickness of 0.5-3.0mm and the width of 0.5-6 mm. Softening the conductor at 500-800 deg.C. The outer periphery of the softened conductor is coated with a high adhesion layer varnish Ulmide-D28. The conductor coated with the varnish for the high-adhesion layer is baked in a heating furnace at an inlet temperature of 200 to 300 ℃ and an outlet temperature of 400 to 600 ℃. The above coating and baking were repeated to obtain a high adhesion layer having a thickness of 5 μm. Then, a varnish for an insulating film is applied to the surface of the high-adhesion layer. The insulating coating varnish was also Ulmide-D28. The varnish for an insulating film does not contain silica. The conductor coated with the varnish for the insulating coating film is continuously baked in a heating furnace at an inlet temperature of 200 to 300 ℃ and an outlet temperature of 400 to 600 ℃. The same coating and baking were repeated to obtain an insulating coating layer having a thickness of 55 μm.
Comparative example 2
Preparing an electric wire: and drawing the conductor with the diameter of 8mm to the diameter of 4-5mm by using a drawing die. The wire drawing die is in the shape of a flat angle with the thickness of 0.5-3.0mm and the width of 0.5-6 mm. Softening the conductor at 500-800 deg.C. The softened outer periphery of the conductor was coated with a varnish for a high adhesion layer Ulmide-D28. The conductor coated with the varnish for the high-adhesion layer is baked in a heating furnace at an inlet temperature of 200 to 300 ℃ and an outlet temperature of 400 to 600 ℃. The above coating and baking were repeated to obtain a high adhesion layer having a thickness of 5 μm. Then, a surge-resistant varnish is applied to the surface of the high-adhesion layer. The surge-resistant varnish for the surge-resistant layer was Surgetect-D25 (20), and included Ulmide-D28 varnish as a base varnish and silica in an amount of 20phr of the base varnish. The size of the silica is 1-10 μm. The conductor coated with the surge-resistant varnish is continuously baked in a heating furnace at an inlet temperature of 200 to 300 ℃ and an outlet temperature of 400 to 600 ℃. The same coating and baking as above were repeated to obtain a surge-resistant layer having a thickness of 55 μm.
Comparative example 3
Preparing an electric wire: and drawing the conductor with the diameter of 8mm to the diameter of 4-5mm by using a drawing die. The wire drawing die is in the shape of a flat angle with the thickness of 0.5-3.0mm and the width of 0.5-6 mm. Softening the conductor at 500-800 deg.C. The softened outer periphery of the conductor was coated with a varnish for a high adhesion layer Ulmide-D28. The conductor coated with the varnish for the high-adhesion layer is baked in a heating furnace at an inlet temperature of 200 to 300 ℃ and an outlet temperature of 400 to 600 ℃. The above coating and baking were repeated to obtain a high adhesion layer having a thickness of 5 μm. Then, a surge-resistant varnish is applied to the surface of the high-adhesion layer. The surge-resistant varnish for the surge-resistant layer was Surgetect-D25 (20), and included Ulmide-D28 varnish as a base varnish and silica in an amount of 20phr of the base varnish. The size of the silica is 1-10 μm. The conductor coated with the surge-resistant varnish is continuously baked in a heating furnace at an inlet temperature of 200 to 300 ℃ and an outlet temperature of 400 to 600 ℃. The same coating and baking were repeated to obtain a surge-resistant layer having a thickness of 40 μm. Then, a varnish for an insulating film is applied to the surface of the surge-resistant layer. The insulating coating varnish was also Ulmide-D28. The varnish for an insulating film does not contain silica. The conductor coated with the varnish for the insulating coating is continuously baked in a heating furnace at an inlet temperature of 200 to 300 ℃ and an outlet temperature of 400 to 600 ℃. The same coating and baking were repeated to obtain an insulating coating layer having a thickness of 15 μm.
Comparative example 4
Substantially the same as in comparative example 2, except that: the varnish for the surge-resistant layer includes Surgetect-D25 (10), includes Ulmide-D28 varnish as a base varnish, and silica in an amount of 10phr of the base varnish. The size of the silica is 1-10 μm.
Example 1
Preparing an electric wire: and drawing the conductor with the diameter of 8mm to the diameter of 4-5mm by using a drawing die. The wire drawing die is in the shape of a flat angle with the thickness of 0.5-3.0mm and the width of 0.5-6 mm. Softening the conductor at 500-800 deg.C. The softened outer periphery of the conductor is coated with a varnish for a high adhesion layer. The varnish for the high adhesion layer is Ulmide-D28D varnish. The conductor coated with the varnish for the high-adhesion layer is baked in a heating furnace at an inlet temperature of 200 to 300 ℃ and an outlet temperature of 400 to 600 ℃. The above coating and baking were repeated to obtain a highly adhesive layer having a thickness of 5 μm. Then, a surge-resistant varnish is applied to the surface of the high-adhesion layer. The surge-resistant varnish for the surge-resistant layer was Surgetect-D25 (20), and included Ulmide-D28 varnish as a base varnish and silica in an amount of 20phr of the base varnish. The size of the silica is 10-30nm. The conductor coated with the surge-resistant varnish is continuously baked in a heating furnace at an inlet temperature of 200 to 300 ℃ and an outlet temperature of 400 to 600 ℃. The same coating and baking as above were repeated to obtain a surge-resistant layer having a thickness of 55 μm.
Example 2
Essentially the same as example 1, except that: the surge-resistant varnish for the surge-resistant layer was Surgetect-D25 (15), and included Ulmide-D28 varnish as a base varnish and silica 15phr of the base varnish. The size of the silica is 10-30nm.
Example 3
Essentially the same as example 1, except that: the surge-resistant varnish for the surge-resistant layer was Surgetect-D25 (25), and included Ulmide-D28 varnish as a base varnish and silica in an amount of 25phr of the base varnish. The size of the silica is 10-30nm.
Example 4
Essentially the same as example 1, except that: the varnish for surge resistant layer was Surgetect-D25 (20) and included Ulmide-D28 varnish as a base varnish and silica in an amount of 20phr based on the base varnish. The size of the silica is 10-30nm.
Example 5
Essentially the same as example 1, except that: the varnish for the surge-resistant layer was Surgetect-D25WH (20), and included BPDA70/PMDA30/ODA100 varnish as a base varnish and silica in an amount of 20phr of the base varnish. The size of the silica is 10-30nm.
Example 6
Essentially the same as example 1, except that: the surge-resistant varnish for the surge-resistant layer was Surgetect-D25 (30), and included Ulmide-D28 varnish as a base varnish and silica in an amount of 30phr of the base varnish. The size of the silica is 10-30nm.
Example 7
Essentially the same as example 1, except that: the surge-resistant varnish for the surge-resistant layer was Surgetect-D25 (32.5), and included Ulmide-D28 varnish as a base varnish and silica in an amount of 32.5phr of the base varnish. The size of the silica is 10-30nm.
Example 8
Essentially the same as example 1, except that: the surge-resistant varnish for the surge-resistant layer was Surgetect-D25 (35), and included Ulmide-D28 varnish as a base varnish and silica in an amount of 35phr of the base varnish. The size of the silica is 10-30nm.
TABLE 1
Figure BDA0003823245790000081
Figure BDA0003823245790000091
Measurement of V-t: under the test environment temperature of 25 ℃, the voltage of 1500Vp is applied to the coating at the frequency of 50kHz, and the time when the coating burns out and the short-circuit wire breaks is the V-t failure time. The voltage is sinusoidal.
The flexibility is an index indicating the toughness of the coating film, and the flexibility test is evaluated based on JIS C3216-3 2011 5.1.1. A wire having a length of 400mm or more was cut from a bobbin (bobbin) and elongated by 10%. The 400mm center portion of the cut wire was edgewise bent at R2.0mm at an angle of 180 ℃.
The V-t failure time of the high-voltage load electric wire was significantly prolonged in example 1 compared to comparative example 2, since no rupture occurred in the sheath. In the conventional electric wire, the flexibility of the electric wire is reduced and the surge resistance is improved with the increase of the amount of silica used in the surge-resistant varnish. However, referring to Table 1, it can be found that the V-t failure time of the high-voltage load electric wire is further prolonged in examples 3 and 6 to 8 as compared with example 1. The invention controls the size and uniform dispersion of the silicon dioxide of the surge-resistant varnish, maintains the flexibility of the electric wire and improves the surge-resistant performance.

Claims (10)

1. A high-voltage load wire is characterized by comprising a conductor, and a double-layer structure of a high-adhesion layer and a surge-resistant layer which are positioned near the conductor, wherein the double-layer structure comprises the high-adhesion layer covering the periphery of the conductor and the surge-resistant layer positioned on the surface of the high-adhesion layer.
2. The high-voltage load wire according to claim 1, wherein the varnish for the high-adhesion layer forming the high-adhesion layer includes one of a polyester imide varnish, a polyamide imide varnish, a polyimide varnish, a polyamide varnish, a polyvinyl formal varnish, a polyurethane varnish, and a polyester varnish.
3. The high-voltage load wire according to claim 1 or 2, wherein the thickness of the high-adhesion layer is 1 to 10 μm.
4. The high-voltage load electric wire according to any one of claims 1 to 3, wherein the varnish for surge-resistant layer forming the surge-resistant layer comprises a base varnish and silica in an amount of 15 to 35phr of the base varnish.
5. The high-voltage load wire according to claim 4, wherein the silica is present in an amount of 20 to 35phr based on the base varnish.
6. The high-voltage load wire according to claim 4 or 5, wherein the silica has a size of 10 to 30nm.
7. The high-voltage load wire according to any one of claims 1 to 6, wherein the surge-resistant layer has a thickness of 50 to 55 μm.
8. The high-voltage load wire according to any one of claims 1 to 7, wherein the high-voltage load wire does not include an insulating coating layer provided on a surge-resistant layer surface.
9. The high-voltage load electric wire according to any one of claims 1 to 8, wherein the high-voltage load electric wire has a V-t failure time of 400 hours or more.
10. The high-voltage load wire according to claim 9, wherein the high-voltage load wire has a V-t failure time of 700 hours or more.
CN202211049351.2A 2022-08-30 2022-08-30 High-voltage load wire Pending CN115424770A (en)

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