JP4594615B2 - Insulated wire and insulated coil - Google Patents

Description

  The present invention relates to an insulated wire and an insulated coil, and more particularly, to an insulated wire and an insulated coil that have excellent heat resistance and are highly resistant to peeling or cracking of an insulating layer (excellent flexibility).

Conventionally, as a method of manufacturing an insulated wire, it is known to provide an insulating coating obtained by electrodeposition and baking an insulating resin varnish (electrodeposition liquid) on the outer periphery of a conductor wire. For example, Patent Document 1 discloses a rectangular insulated wire in which an insulating coating is formed by electrodeposition and baking a water-dispersed varnish in which an epoxy-modified acrylic resin having a specific concentration is dispersed on the outer periphery of a conductor wire having a rectangular cross section. ing. In this insulated wire, the thickness of the portion where the insulating coating covering the outer periphery of the conductor wire having a flat cross-sectional shape (hereinafter also referred to as “flat conductor wire”) covers the corner portion rather than the portion covering the flat portion of the conductor wire. Is formed so that the withstand voltage characteristic of the electric wire is improved. However, such insulated wires do not have sufficient heat resistance. On the other hand, polyimide is exemplified as a coating material having heat resistance, but most of the means for coating is by dipping. In dipping, when the cross-sectional shape of the conductor wire is flat, there is a problem that a sufficient film thickness cannot be obtained at the corner (corner). Specifically, only a thickness about 0.2 times the flat portion can be obtained. Moreover, the film thickness obtained by dipping has a limit in making it thin from said point. Therefore, the present inventors tried to obtain a highly heat-resistant insulated wire by electrodeposition and baking a polyimide varnish (Patent Documents 2 and 3) having excellent heat resistance on the outer periphery of the flat conductor wire. However, the insulated wires obtained by electrodepositing and baking these polyimide varnishes on the conductor wires have high heat resistance. However, when the insulated wires are bent, they are insulated by winding the insulated wires with edgewise coils. When the coil was formed, there was a problem that the electrodeposition film as an insulating layer was broken and peeled off from the conductor wire. That is, it has been found that an insulated wire using a known polyimide electrodeposition coating has a problem of insufficient flexibility.
JP-A-7-320573 JP-A-9-104839 JP-A-9-124978

In view of the above circumstances, the problem of the present invention is that it has high heat resistance and is less likely to cause peeling or cracking of the insulating layer when the insulated wire is bent (that is, excellent in flexibility). An insulated wire and an insulated coil using the insulated wire are provided.
Furthermore, the other subject of this invention has high heat resistance, and when an insulated electric wire is bent, it is hard to produce peeling and a crack of an insulating layer (that is, it is excellent in flexibility), An object of the present invention is to provide an insulated wire having good voltage resistance and an insulated coil using the insulated wire.

In order to solve the above problems, the present invention employs the following configuration.
That is, the present invention
(1) A block copolymer polyimide containing a siloxane bond in the main chain of the polyimide and having an anionic group in the molecule, having a weight average molecular weight (Mw) of 45,000 to 90,000, a number average molecular weight ( An insulated wire comprising an electrodeposited coating of block copolymerized polyimide having a Mn) of 20,000 to 40,000 as an insulating layer around the conductor wire;
(2) The above (1) description, wherein the intrinsic logarithmic viscosity (25 ° C. ) of the block copolymerized polyimide is 5,000 to 50,000 mPa · s in a 20 wt% NMP (N-methyl-2-pyrrolidone) solution. Insulated wire ,
(3) The siloxane bond in the main chain of the polyimide is a siloxane bond derived from a siloxane bond-containing diamine compound, and the siloxane bond-containing diamine compound is bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4 -Aminophenoxy) -1,1,3,3-tetramethyldisiloxane, and one or more selected from the group consisting of compounds represented by the following general formula (I), (1) Or the insulated wire according to (2) ,

(In the formula, each R independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxyl groups, and l and m are each independently And n represents an integer of 1 to 20.)
( 4 ) The above (1) to (3) , wherein the diamine component of the block copolymerized polyimide comprises a siloxane bond-containing diamine compound and an aromatic diamine, and the tetracarboxylic dianhydride component comprises an aromatic tetracarboxylic dianhydride. Insulated wires according to any of the
( 5 ) The insulated wire according to ( 4 ) above, wherein the aromatic diamine contains at least an aromatic diaminocarboxylic acid and / or an aromatic diaminosulfonic acid,
( 6 ) The aromatic tetracarboxylic dianhydride is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis- (3,4-dicarboxyphenyl) ether dianhydride, 3,3 ′. , 4,4′-benzophenone tetracarboxylic dianhydride and 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, the above ( 4 ) or ( 5 ) Insulated wire as described,
( 7 ) The insulated wire according to any one of (1) to ( 6 ), wherein the conductor wire has a flat cross-sectional shape.
( 8 ) The insulated wire according to any one of (1) to ( 7 ), wherein the conductor wire is made of copper or a copper alloy.
(9) The thickness of the insulating film formed on the flat surface of the conductor wires periphery is 1.5～30Myuemu, insulated wire described above SL (7),
(10) An electrodeposition film of block copolymerized polyimide is further added to a solution obtained by dissolving the block copolymerized polyimide in an organic polar solvent, a water-poor solvent for polyimide and a neutralizing agent for neutralizing polyimide. The insulated wire according to any one of the above (1) to (9), and ( 11 ) the above (1) to ( 10 ) , which is formed by electrodepositing and baking the solution dispersion type varnish on the outer periphery of the conductor wire. insulating coils of insulated wire were wound edgewise coil winding or alignment of any one of) relates to.

  ADVANTAGE OF THE INVENTION According to this invention, while having favorable heat resistance, it is hard to produce a peeling and a crack of an insulating layer at the time of the bending process of an electric wire, and can obtain the insulated wire excellent in flexibility. In particular, in an insulated wire having a flat cross-sectional shape of the conductor wire, an electrodeposition coating is stably formed at the corner portion of the outer periphery of the conductor wire, and the thickness of the coating covering the flat portion of the outer periphery of the conductor wire can be reduced. In addition to achieving excellent heat resistance, withstand voltage characteristics and processing resistance of the insulated wire, it is possible to achieve downsizing (weight reduction). In addition, in the insulated coil of the present invention obtained by winding an edge-wise coil of an insulated wire having a flat cross-sectional shape, the insulating layer (insulating film) of the wound insulated wire is adhered to the conductor wire with high adhesion. Therefore, the insulated coil has high reliability and high durability.

Hereinafter, the present invention will be described in detail.
The insulated wire of the present invention is a block copolymer polyimide containing a siloxane bond in the main chain of polyimide and having an anionic group in the molecule (hereinafter also abbreviated as “siloxane copolymer containing block copolymer polyimide”). The coating film is provided as an insulating layer around the conductor wire.

  Here, “block copolymerized polyimide” means that a tetracarboxylic dianhydride and a diamine are heated to form an imide oligomer (first stage reaction), and then the same as the tetracarboxylic dianhydride described above. Alternatively, by reacting with different tetracarboxylic dianhydrides or / and diamines different from the above diamines (second stage reaction), random copolymerization caused by exchange reaction occurring between amic acids can be prevented. The term “electrodeposition coating” means “insulation obtained by subjecting a coating obtained by electrodeposition of a varnish (electrodeposition solution) to heat treatment (baking treatment)” It is the “coating”.

  In the insulated wire of the present invention, the insulating layer formed by the electrodeposition coating of the siloxane bond-containing block copolymerized polyimide adheres to the conductor wire with high adhesion, and when the insulated wire is bent, the insulating layer is formed from the conductor wire. It does not peel off or cracks in the insulating layer, and has excellent processing resistance. In particular, the electrodeposited film of polyimide satisfactorily covers the outer periphery of the conductor wire without causing pinholes, and in the case of a conductor wire having a flat cross-sectional shape, not only the flat end portion of the outer periphery but also the corner portion. Can be obtained, so that a rectangular insulated wire having excellent heat resistance, processing resistance and voltage resistance can be obtained.

  In the present invention, in a block copolymer polyimide containing a siloxane bond in the main chain of polyimide and having an anionic group in the molecule, the siloxane bond in the main chain is a siloxane bond derived from a tetracarboxylic dianhydride component. Or a siloxane bond derived from a diamine component, preferably a siloxane bond derived from a diamine component, and usually a siloxane bond (—Si—O—) in the molecular skeleton at least part of the diamine component. A block copolymerized polyimide obtained by using a diamine compound having benzene (hereinafter sometimes referred to as “siloxane bond-containing diamine compound”) is used.

  In the present invention, the siloxane bond-containing diamine compound can be used without particular limitation as long as it can be imidized with tetracarboxylic dianhydride. For example, bis (4-aminophenoxy) dimethylsilane, 1, 3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane and general formula (I):

(In the formula, each R independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxyl groups, and l and m are each independently And an integer of 1 to 4 and n represents an integer of 1 to 20.). The compound represented by the general formula (I) includes a single compound in which n is 1 or 2, and polysiloxane diamine.

  In R in Formula (I), the alkyl group and the cycloalkyl group preferably have 1 to 6 carbon atoms, and more preferably 1 to 2 carbon atoms. In the phenyl group substituted with 1 to 3 alkyl groups or alkoxyl groups, 1 to 3 alkyl groups or alkoxyl groups may be the same or different when they are 2 or 3 May be. Moreover, as for an alkyl group and an alkoxyl group, C1-C6 is respectively preferable, and 1-2 are more preferable.

  In the compound represented by the general formula (I), R in the formula is preferably an alkyl group (particularly a methyl group) or a phenyl group, and in the formula, l and m are 2 to 3, and n is 5 to 15 The polysiloxane diamine in

Preferred examples of the polysiloxane diamine include bis (γ-aminopropyl) polydimethylsiloxane (in the formula (I), 1 and m are 3, R ₁ and R ₂ are methyl groups), bis (γ-amino). Propyl) polydiphenylsiloxane (in the formula (I), 1 and m are 3, and R ₁ and R ₂ are phenyl groups).

  In the present invention, the siloxane bond-containing diamine compound may be used alone or in combination of two or more. A particularly preferred one is bis (4-aminophenoxy) dimethylsilane. 1,3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane and a compound selected from the group consisting of the compounds represented by formula (I).

  In addition, the said siloxane bond containing diamine compound may use a commercial item, and can use what is sold from Shin-Etsu Chemical Co., Toray Dow Corning, Chisso, as it is. Specifically, KF-8010 (bis (γ-aminopropyl) polydimethylsiloxane: amino group equivalent of about 450), X-22-161A (bis (γ-aminopropyl) polydimethylsiloxane: Shin-Etsu Chemical Co., Ltd .: Amino group equivalent of about 840) and the like.

  In the present invention, the siloxane bond-containing block copolymerized polyimide uses, for example, a substantially equal amount of a diamine compound containing at least a siloxane bond-containing diamine compound and tetracarboxylic dianhydride in the presence of a catalyst consisting of a lactone and a base, It can be obtained by heating and polycondensation in an organic polar solvent. That is, the tetracarboxylic dianhydride and the diamine compound are heated in the first stage to form an imide oligomer, and then the diamine compound or / and the tetracarboxylic dianhydride are further added to perform the second stage reaction, Block copolymerize. At this time, a siloxane bond-containing diamine compound is incorporated as a block segment as the diamine compound used in the first stage and / or the second stage. In the reaction, an acid anhydride such as phthalic anhydride or an amine compound such as aniline may be added to the reaction system as a terminal terminator. Examples of the organic polar solvent include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and γ-butyrolactone (γBL). , Anisole, cyclohexanone, tetramethylurea, sulfolane and the like, preferably NMP from the viewpoint of compatibility with polyimide.

  In this invention, the usage-amount of a siloxane bond containing diamine compound is the quantity from which the imide unit which uses this siloxane bond containing diamine compound as a diamine component becomes 5-90 mol% in all the repeating units (imide unit) which comprise a polyimide. Is preferable, the amount of 10 to 70 mol% is more preferable, and the amount of 15 to 50 mol% is particularly preferable. When the amount of the imide unit based on the siloxane bond-containing diamine compound is less than 10 mol%, such a polyimide electrodeposition film has poor adhesion and elongation to the conductor wire, and sufficient flexibility. This is not preferable because it is difficult to obtain and easily peels off or cracks. Moreover, when the amount of the imide unit based on the siloxane bond-containing diamine compound exceeds 90 mol%, the heat resistance tends to decrease, which is not preferable.

  The insulated wire of the present invention is obtained by electrodepositing the siloxane bond-containing block copolymerized polyimide varnish (that is, a varnish containing a siloxane bond-containing block copolymerized polyimide as a resin component) on the outer periphery of a conductor wire. Manufactured by baking. Regarding the preparation of a polyimide varnish (electrodeposition liquid) and the formation of an electrodeposition film, for example, polyimides described in JP-A-49-52252, JP-A-52-32943, JP-A-63-11111, etc. A method is known in which an electrode is deposited using a varnish (electrodeposition liquid) in which a poor solvent and water are added to an organic polar solvent in which the polyamic acid, which is a precursor of A, is dissolved, and then the electrodeposition film is heated to form an imide film. However, in the case of this method, the polyamic acid electrodeposition varnish (electrodeposition liquid) has poor storage stability because the polyamic acid is easily decomposed, which adversely affects the physical properties of the coating film after electrodeposition. There is a case. Therefore, in the present invention, the following method is used.

  That is, a solution in which a siloxane bond-containing block copolymerized polyimide having an anion group (carboxylic acid group, sulfonic acid group, etc.) introduced therein is dissolved in an organic polar solvent is obtained, and water and a poor solvent for polyimide and a polyimide are neutralized to the solution. A solution-dispersed varnish to which a neutralizing agent (basic compound) is further added is prepared, and the solution-dispersed varnish is electrodeposited and baked on the adherend to form a film. According to this method, there are no disadvantages as in the conventional method described above, and even for a conductor wire having a flat cross-sectional shape, not only a flat portion on the outer periphery of the conductor wire but also a corner portion without generating pinholes. It is possible to form an electrodeposition film that is well coated.

  In the present invention, since the siloxane bond-containing block copolymerized polyimide is used for insulating coatings (insulating layers) of electric wires, it is necessary to have sufficient heat resistance. Usually, the diamine component is aromatic together with the siloxane bond-containing diamine compound. Group diamines are used. Examples of the aromatic diamine include m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4′-diamino-3,3′-dimethyl-1,1′-biphenyl, and 4,4 ′. -Diamino-3,3'-dihydroxy-1,1'-biphenyl, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-amino) Phenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2′-bis [4- (4-aminophenyl) Noxy) phenyl] propane, 2,2′-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) ) Phenyl] sulfone, 3,5-diaminobenzoic acid, 3,3′-dicarboxy-4,4′-diaminophenylmethane, 2,4-diaminophenylacetic acid, 2,5-diaminoterephthalic acid, 3,5- Diaminoparatoluic acid, 3,5-diamino-2-naphthalenecarboxylic acid, 1,4-diamino-2-naphthalenecarboxylic acid, 2,6-diaminopyridine, 2,6-diamino-4-methylpyridine, 4,4 '-(9-Fluorenylidene) dianiline, 4,4'-diaminodiphenylsulfone, α, α-bis (4-aminophenyl) -1, - diisopropylbenzene, and the like. These compounds may be used alone or in combination of two or more.

  In addition, as described above, in the present invention, the siloxane bond-containing block copolymerized polyimide is a polyimide into which an anionic group such as a carboxylic acid group or a sulfonic acid group is introduced in order to obtain a neutralized salt in the varnish. Therefore, what has anionic groups, such as a carboxylic acid group and a sulfonic acid group, is used for at least one part of diamine compounds other than a siloxane bond containing diamine compound. Therefore, among the aromatic diamines exemplified above, at least a carboxylic acid group-containing aromatic diamine (aromatic diaminocarboxylic acid) and / or a sulfonic acid group-containing aromatic diamine (aromatic diaminosulfonic acid) is used. Among the above, carboxylic acid group-containing aromatic diamine (aromatic diaminocarboxylic acid) is 3,5-diaminobenzoic acid, 3,3′-dicarboxy-4,4′-diaminophenylmethane, 2,4-diamino. Phenylacetic acid, 2,5-diaminoterephthalic acid, 3,5-diaminoparatoluic acid, 3,5-diamino-2-naphthalene carboxylic acid, 1,4-diamino-2-naphthalene carboxylic acid, containing sulfonic acid group The aromatic diamine (aromatic diaminosulfonic acid) is 2,5-diaminobenzenesulfonic acid, 4,4′-diamino-2,2′-stilbene disulfone, o-tolidine disulfonic acid.

  In the present invention, the content of the carboxylic acid group-containing aromatic diamine (aromatic diaminocarboxylic acid) or / and the sulfonic acid group-containing aromatic diamine (aromatic diaminosulfonic acid) in the siloxane bond-containing block copolymerized polyimide is diamine. It is 10 mol% or more with respect to the whole component, Furthermore, it is 15 mol% or more.

  In the present invention, the tetracarboxylic dianhydride component in the siloxane bond-containing block copolymerized polyimide is usually aromatic from the viewpoint of the heat resistance, long-term stability, electrodeposition performance, adhesion to metal, etc. of the polyimide. Tetracarboxylic dianhydride is used. Specific examples of the aromatic tetracarboxylic dianhydride include, for example, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis- (3,4-di Carboxyphenyl) ether dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2-bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 3,3 Examples include ', 4,4'-biphenylsulfonetetracarboxylic dianhydride, bicyclo [2,2,2,] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, and the like. These may be used alone or in combination of two or more. Among these, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride from the viewpoints of heat resistance, adhesion to conductor wires, compatibility with siloxane bond-containing diamine compounds, polymerization rate of polyimide, etc. Bis- (3,4-dicarboxyphenyl) ether dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic acid dianhydride Anhydrides are particularly preferably used.

  In the present invention, the siloxane bond-containing block copolymerized polyimide is 5,000 to 50,000 mPa · s when the intrinsic logarithmic viscosity (25 ° C.) is 20 wt% in an NMP (N-methyl-2-pyrrolidone) solution. Is preferable, and 5,000 to 15,000 mPa · s is more preferable. When the intrinsic log viscosity exceeds 50,000 mPa · s, the coating uniformity of the produced electrodeposition film tends to be impaired.

  The weight average molecular weight (Mw) of the siloxane bond-containing block copolymerized polyimide is preferably 20,000 to 150,000, and particularly preferably 45,000 to 90,000 in terms of polystyrene. When the weight average molecular weight is less than 20,000, the heat resistance of the electrodeposition coating is inferior, the coating surface is roughened, the aesthetics of the insulated wire is lowered, and the commercial value may be lowered. On the other hand, if the weight average molecular weight is larger than 150,000, viscosity increase or gelation may progress in the solution, which may impair electrodeposition performance. Further, the number average molecular weight (Mn) in the siloxane bond-containing block copolymerized polyimide is preferably 1,000 to 70,000, more preferably 20,000 to 40,000 in terms of polystyrene. When the number average molecular weight is less than 1,000, the electrodeposition efficiency is poor, it takes time to obtain an electrodeposition film with a desired film thickness, and the productivity of the insulated wire tends to decrease, and the heat resistance of the insulated wire Moreover, there is a possibility that the necessary requirements for the voltage resistance cannot be satisfied. When the number average molecular weight exceeds 70,000, the intrinsic viscosity becomes high, the foaming property is lowered (the bubbles taken into the coating film cannot be removed), and the workability tends to be lowered.

  Here, the weight average molecular weight and the number average molecular weight are polystyrene-converted values by GPC, using HLC-8220 manufactured by Tosoh Corporation as a GPC apparatus, and TSK-gel Super HM-M (Column No.-D0038) as a column. The measured value.

In the present invention, the preparation of the varnish (electrodeposition liquid) containing the siloxane bond-containing block copolymerized polyimide is specifically performed as follows.
First, a diamine compound and a tetracarboxylic dianhydride in the presence of an acid catalyst in at least one organic polar solvent selected from NMP, DMF, DMAc, γ-butyrolactone, DMSO, anisole, cyclohexanone, tetramethylurea, sulfolane and the like Are reacted at 160-180 ° C. while distilling off the water produced by azeotropic distillation to produce oligomers (first stage reaction). Next, a tetracarboxylic dianhydride or / and a diamine compound are further added and heated to 160 to 180 ° C. to perform a second stage reaction (heating). At this time, the block copolymerization polyimide which contains a siloxane bond in a principal chain is obtained by using a siloxane bond containing diamine compound as a diamine compound used at a 1st step or / and a 2nd step. The solid content concentration of the reaction solution thus obtained is preferably 10 to 40% by weight, more preferably 20 to 30% by weight. Next, the block copolymerized polyimide dissolved in the polar solvent is neutralized with a basic compound, and water and a poor solvent for polyimide are added to obtain an electrodeposition solution. As the basic compound, N, N-dimethylethanolamine, triethylamine, triethanolamine, N-dimethylbenzylamine, N-methylmorpholine and the like are used. The amount of the basic compound used is such that the polyimide is stably dissolved or dispersed in the aqueous solution, and is usually about 30 to 200 mol% of the theoretical neutralization amount. The poor solvent is preferably an alcohol having a phenyl group, a furfuryl group or a naphthyl group. Specifically, benzyl alcohol, 2-phenylethyl alcohol, 4-methylbenzyl alcohol, 4-methoxybenzyl alcohol, 4-methoxybenzyl alcohol, Examples include chlorobenzyl alcohol, 4-nitrobenzyl alcohol, phenoxy-2-ethanol, cinnamyl alcohol, furfuryl alcohol, and naphthyl carbinol. The amount of the polar solvent in the varnish (electrodeposition liquid) is preferably 1.5 to 10 parts by weight, more preferably 2.4 to 6 parts by weight, and more preferably 2.4 to 6 parts by weight of polyimide. 0.1 to 5 parts by weight per part is preferable, and more preferably 1 to 3 parts by weight.

  In the present invention, the electrodeposition conditions for forming an electrodeposition film of polyimide varnish on the outer periphery of the conductor wire may be a constant current method or a constant voltage method. In the case of the constant current method, for example, the current value is fixed at 50 mA, and the upper limit of the DC voltage is 50 to 250 V, preferably 100 to 200 V. When the upper limit of the electrodeposition voltage is lower than 50V, it tends to be difficult to form a coating film by electrodeposition, and when it is higher than 250V, generation of oxygen from the coating object and elution of copper ions occur. It tends to be intense and difficult to form a uniform coating film. In the case of the constant voltage method, the voltage value may be fixed at 50 to 250 V, preferably 100 to 200 V, and if it is fixed at a voltage value lower than 50 V, it tends to be difficult to form a coating film by electrodeposition. When the voltage value is higher than 250 V, the generation of oxygen from the coated object and the elution of copper ions become violent, and it tends to be difficult to form a uniform coating film. The electrodeposition time is usually 15 to 120 seconds, preferably about 30 to 90 seconds, in either the constant current method or the constant voltage method. The temperature of the varnish (electrodeposition liquid) during electrodeposition is constant current. In any of the method and the constant voltage method, the temperature is preferably 20 to 70 ° C, more preferably 25 to 30 ° C.

  Baking of the coating film formed by electrodeposition is performed by performing the first stage baking process at 70 to 110 ° C. for 10 to 60 minutes, and then performing the second stage baking process at 160 to 180 ° C. for 10 to 60 minutes. Further, it is preferable to perform a third stage baking process at 200 to 220 ° C. for 30 to 60 minutes. By performing such a three-stage baking process, it is possible to form a sufficiently cured polyimide film that adheres to the conductor wire with high adhesion.

  In the present invention, the varnish electrodeposition and baking operations are preferably performed, for example, with an apparatus as shown in FIG. That is, the conductor wire 11 wound around the roll 10 is pulled out and passed through the electrodeposition bus 12 filled with the varnish (electrodeposition liquid) 13 while being connected to the anode side of the AC power source. A cathode tube 14 is disposed in the electrodeposition bus 12, and polyimide is applied to the conductor wire due to the potential difference between the conductor wire 11 serving as the anode and the cathode tube 14 serving as the cathode due to the application of the voltage when passing through the conductor wire 11. 11 is deposited almost uniformly. After the electrodeposition bus 12, the conductor wire 11 is passed through the drying device 15. In the drying device 15, the water in the polyimide deposited on the conductor wire 11 evaporates. After passing through the drying device 15, a coating film (insulating layer) made of polyimide is formed by passing through a baking furnace 16, and the insulated conductor is wound up by a roll 20. By performing the electrodeposition and baking operations of the varnish with such an apparatus, the target insulated wire can be continuously manufactured.

  In the present invention, the material of the conductor wire of the insulated wire is not particularly limited, but from the viewpoint of conductivity, copper, copper alloy, copper clad aluminum, aluminum, galvanized iron, silver and the like are mentioned. preferable. Also, the shape of the insulated wire is not particularly limited, and is a circular insulated wire having a circular cross-sectional shape (that is, an insulated wire in which an insulating layer made of an electrodeposition coating is provided on the outer periphery of a conductor wire having a circular cross-sectional shape). However, it may be a flat insulated wire having a flat cross-sectional shape (that is, an insulated wire having an insulating layer formed by an electrodeposition coating on the outer periphery of a conductor wire having a flat cross-sectional shape). Depending on the specific application, a round insulated wire or a flat insulated wire is selected. The “flat angle (shape)” in the present invention means a rectangle or a square (shape). In the insulated wire of the present invention, the circular insulated wire is used for applications such as general-purpose motors and electromagnetic coils. In addition, the flat insulated wires are used for applications such as drive motors of various electric devices, coils of portable precision devices such as mobile phones utilizing light weight and high output.

  In the insulated wire of the present invention, since the insulating layer covering the outer periphery of the conductor wire is formed of a polyimide electrodeposition film having a siloxane bond in the main chain of the polyimide, the insulating layer generates a pinhole in the outer periphery of the conductor wire Insulated electric wires that are uniformly coated and have a flexible insulating layer that is in close contact with the conductor wire with high adhesion. In particular, not only for conductor wires having a circular cross-sectional shape but also for conductor wires having a flat cross-sectional shape, the insulating layer uniformly coats the outer periphery with high adhesion, and the outer periphery of the conductor wire is flat. As a result, a rectangular insulated wire in which not only the corners but also the corners are well coated with the polyimide coating can be obtained. Therefore, the insulated wire of the present invention has good heat resistance and voltage resistance, and is excellent in processing resistance, in which the insulating layer (electrodeposition coating) is not easily peeled off or cracked when the insulated wire is bent. It will have.

  In the insulated wire of the present invention, the outer diameter (diameter) of the conductor wire in the case of a circular insulated wire is preferably 0.05 to 20 mm, more preferably 0.1 to 10 mm. The thickness of the electrodeposited coating (insulating layer) of the polyimide varnish is preferably 1.5 to 30 μm, more preferably 5 to 20 μm. When the thickness of the insulating layer is less than 1.5 μm, it is difficult to obtain a sufficient AC (alternating current) withstand voltage effect, and even if the thickness exceeds 30 μm, no significant improvement in the AC withstand voltage effect is observed. The size of the insulated wire obtained will become large.

  FIG. 1 is a diagram showing a simplified cross section of a flat insulated wire of the present invention (cross section in a direction perpendicular to the longitudinal direction of the insulated wire), and a flat conductor wire in the flat insulated wire 1 of the present invention. 2 (t1 in FIG. 1) is preferably 0.005 to 1.0 mm, more preferably 0.01 to 0.50 mm, and the width (w1 in FIG. 1) is preferably 0.1 to 20 mm. It is. Moreover, the thickness of the insulating layer 3 by the electrodeposition coating of the polyimide varnish is preferably 1.5 to 30 μm, more preferably 5 to 20 μm at the flat portion on the outer periphery of the conductor wire 2. When the thickness is less than 1.5 μm, it is difficult to obtain a sufficient AC (alternating current) withstand voltage effect, and even if the thickness exceeds 30 μm, a significant improvement in the AC withstand voltage effect is not seen and further obtained. It only increases the size of the insulated wire. On the other hand, the corner portion on the outer periphery of the conductor wire 2 has a thickness of at least a flat portion in order to prevent a decrease in AC withstand voltage at the corner portion (the corner portion is liable to cause electric field concentration and thus has an influence on withstand voltage characteristics). The thickness is preferably 0.8 times or more, particularly 0.9 times or more. Specifically, the thickness of the corner portion is 0.8 to 2 times the thickness of the flat portion, preferably 0.9 from the viewpoint of withstand voltage characteristics and miniaturization and weight reduction of the insulated wire (coil using the insulated wire). It is -1.5 times, More preferably, it is 1.0 times -1.2 times. When the thickness at the corner portion on the outer periphery of the conductor wire is less than 0.8 times the thickness at the flat portion, the AC withstand voltage at the corner portion is greatly reduced due to electric field concentration. Further, when the thickness at the corner portion of the outer periphery of the conductor wire exceeds twice the thickness at the flat portion, it tends to be difficult to reduce the size and weight. In the present invention, the thickness of the insulating layer covering the outer periphery of the rectangular conductor wire means the insulating layer 3 at the center point of the long side in the rectangular cross section of the rectangular conductor wire 2 as shown in FIG. (D1 in FIG. 1), and the thickness of the insulating layer at the corner of the outer periphery of the flat conductor wire is the length between the long side and the short side in the rectangular cross section of the flat conductor wire 2 The thickness (D2 in FIG. 1) of the insulating layer 3 covering the corner portion is meant.

  The insulated coil of the present invention is an insulated coil obtained by winding the flat insulated wire in the insulated wire of the present invention described above by a known method such as edgewise winding, aligned winding, and alpha (α) winding. In the insulated coil of the present invention, the size of the rectangular insulated wire to be used is not particularly limited, and various sizes are used according to the application of the insulated coil. In addition, since the insulating coil of the present invention is composed of an insulated wire having a flexible electrodeposition coating as an insulating layer, it is also insulated against processing (particularly edgewise winding) when forming an insulating coil. The layer will not peel off or crack.

  The insulated coil of the present invention has excellent heat resistance and voltage resistance as a flat insulated wire wound, and the insulation coating (insulation layer) is not easily peeled off from the conductor wire even when bent. As a result, the insulation coil has not only good performance and voltage resistance but also significantly improved durability. Specific applications of the insulating coil of the present invention include a motor coil, a transformer coil, a substrate mounting component (SMD) coil, a small high performance motor coil, a small electronic device coil, and the like. Among them, it is suitable as a coil for a small high-performance motor and a coil for a small electronic device that are required to be downsized. The pitch of the coil, the outer diameter of the coil, and the like vary depending on various corresponding products and are appropriately determined accordingly.

  The present invention is an insulated wire in which a specific polyimide varnish electrodeposition coating is provided on the outer periphery of a linear conductor. The specific polyimide varnish used in the present invention (that is, a siloxane bond-containing block copolymerized polyimide varnish (electrodeposition) (Liquid)) is an insulating plate (insulating coil plate) in which a plate-like (for example, a cross-sectional shape is a rectangular shape and a planar shape is a ring shape having an open portion) is coated with an insulating plate (insulating coil plate) and an insulating coil obtained by laminating the insulating plate. It can also be applied to insulation coating. That is, an insulating plate is obtained by covering a plate shape (for example, a ring-shaped conductive plate having a flat cross-sectional shape and an open portion in a planar shape) with a varnish electrodeposited coating of a block copolymerized polyimide containing siloxane bond. (Insulating coil plate) and an insulating coil in which it is laminated can be achieved.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the following Example.

Example 1
Production of Block Copolymerization Polyimide Solution Containing Siloxane Bond A separable three-necked flask made of glass was used, and a water acceptor equipped with a stopcock was attached to the lower part of a stirrer, a nitrogen introducing tube and a cooling tube. Nitrogen was circulated, and the reactor was immersed in a silicone oil bath with further stirring and heated to carry out the reaction. First, 58.84 g (0.2 mol) of 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride and bis (γ-aminopropyl) polydimethylsiloxane (KF- manufactured by Shin-Etsu Chemical Co., Ltd.) were placed in a flask. 8010) 97.2 g (0.1 mol), valerolaclone 4 g (0.04 mol), pyridine 6.3 g (0.08 mol), NMP (N-methyl-2-pyrrolidone) 500 g and toluene 80 g were added at room temperature. For 30 minutes, and then the temperature was raised and the reaction was carried out at 180 ° C. for 1 hour with stirring at 200 rpm. After the reaction, 30 ml of toluene-water distillate was removed. The residue was air-cooled to give 64.45 g (0.2 mol) of 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride, 30.43 g (0.2 mol) of 3,5-diaminobenzoic acid. Bis- [4- (3-aminophenoxy) phenyl] sulfone 43.25 g (0.1 mol), NMP 500 g and toluene 100 g were added, stirred at room temperature for 1 hour (200 rpm), then heated to 180 ° C. And stirred for 1 hour. Stirring was performed at 180 ° C. for 3 hours while removing 15 ml of toluene-water distillate and thereafter removing the distillate from the system. Subsequently, 1.1 g of phthalic anhydride and 113 g of NMP were added and the reaction was carried out for 1 hour to complete the reaction. As a result, a 20% polyimide varnish was obtained. The weight average molecular weight and number average molecular weight of the block copolymerized polyimide were 66,000 and 34,000, respectively.

  To 100 g of the 20% polyimide solution obtained above, 3 g of triethylamine (neutralization rate 100 mol%) was added and stirred, and then 62.5 g of NMP was added. Then, 32 g of water was added dropwise to prepare an electrodeposition liquid composition (electrodeposition varnish) having a solid content concentration of 5.0%, pH 8.7, and electrical conductivity of 9.8 ms / m.

Next, the electrodeposition composition (varnish) was electrodeposited on the outer periphery of a circular copper wire (total length 30 cm) having a diameter (φ) of 1.2 cm in cross section under the following electrodeposition conditions.
Distance between electrodes: 3.0cm
Electrodeposition voltage: Constant current method (50 mA) -Voltage (Max 160 V)
Electrodeposition time: 60 seconds

Next, the copper wire electrodeposited with the polyimide composition in this manner is taken out of the electrodeposition bath, washed with water, and then baked at 90 ° C. for 30 minutes, further at 170 ° C. for 30 minutes, and further at 220 ° C. for 30 minutes. A circular insulated copper wire having an insulating layer (average thickness: 17 μm) made of block copolymerized polyimide was obtained.
In addition, the coating thickness of the insulating layer was measured at five locations in a 30 cm length section with a micrometer, and the arithmetic average value was defined as the average thickness (measured from two directions per location). In addition, the coating thickness (average thickness) of the insulating layer of the circular insulated copper wire in the following Comparative Examples 1 to 4 was obtained in the same manner.

  Further, under the same electrodeposition conditions and baking conditions as described above, the polyimide composition is electrodeposited on the outer periphery of a flat copper wire (total length 30 cm) having a cross section of 1.8 mm × 0.08 mm, and baked to obtain siloxane. An insulated rectangular copper wire having an insulating layer made of a bond-containing block copolymerized polyimide was obtained. The average thickness (D1) of the portion covering the flat portion of the flat copper wire of the insulating layer was 15 μm, and the average thickness (D2) of the portion covering the corner portion was 13 μm. The average thickness (D1) here is the thickness of the insulating layer at the midpoint of each of the two long sides of the cross section of the copper wire (rectangle) at the five cross sections of the 30 cm length of the flat insulated copper wire (total) The average thickness (D2) of the portion covering the corner portion is the thickness of the insulating layer at the four corner portions of the copper wire cross section (rectangle) at the five cross sections (total). The average value of 20 thicknesses). The thickness of the insulating layer was measured by image processing from a cross-sectional photograph using a microscope.

Comparative Example 1
Acrylonitrile (5 mol), acrylic acid (1 mol), and glycidyl methacrylate (0.3 mol) are placed in a flask together with ion-exchange water (760 g), lauryl sulfate ester soda (7.5 g) and sodium persulfate (0.13 g). After that, an emulsion polymerization liquid (epoxy / acrylic water dispersion varnish) obtained by reacting the mixture at a temperature of 50 to 60 ° C. for 3 hours was prepared. Using this emulsion polymerization solution as an electrodeposition composition, the same conditions as in Example 1 were used, and the same electrodeposited and baked on a copper wire having a circular cross section and a rectangular copper wire, respectively, as used in Example 1. The round insulation copper wire having an insulating layer (average thickness 17 μm) made of epoxy-modified acrylic resin and the average thickness (D1) of the flat portion of the flat copper wire of the insulating layer made of epoxy-modified acrylic resin is 15 μm and the corner portion is A flat rectangular insulated copper wire having an average thickness (D2) of the covering portion of 23 μm was obtained.

Comparative Example 2
Use a glass separable three-necked flask equipped with a water acceptor with a stopcock at the bottom of the stirrer, nitrogen inlet tube, and cooling tube. The following reaction was carried out with heating inside. That is, 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride 64.44 g (0.2 mol), bis- [4- (3-aminophenoxy) phenyl] sulfone 43.25 g (0.1 Mol), 3 g (0.03 mol) of valerolactone, 4.8 g (0.06 mol) of pyridine, 400 g of NMP (abbreviation of N-methyl-2-pyrrolidone) and 90 g of toluene, and stirred at room temperature for 30 minutes. Then, the temperature was raised, and the reaction was carried out at 180 ° C. for 1 hour with stirring at 200 rpm. After the reaction, 30 ml of toluene-water distillate was removed. The residue was air-cooled, and 3,22,3 ', 4'-benzophenonetetracarboxylic dianhydride (32.22 g, 0.1 mol), 3,5-diaminobenzoic acid (15.22 g, 0.1 mol) Then, 11.01 g (0.1 mol) of 2,6-diaminopyridine, 222 g of NMP and 45 g of toluene were added, and the mixture was stirred at room temperature for 1 hour (200 rpm), then heated to 180 ° C. for 1 hour with stirring. After removing 15 ml of toluene-water distillate and removing the distillate from the system, the reaction was terminated by heating and stirring at 180 ° C. for 3 hours to obtain a 20% polyimide solution. 70 g of NMP was added to 100 g of the polyimide solution thus obtained, 55 g of anisole, 45 g of cyclohexanenone and 2.6 g of N-methylmorpholine (neutralization rate 200 mol%) were added, and 30 g of water was added dropwise with stirring to obtain a solid concentration of 6 An electrodeposition polyimide emulsion composition (varnish) having a pH of 6.8% was obtained. Then, under the same conditions as in Example 1, the composition was electrodeposited and baked on a copper wire having a circular cross section and a rectangular copper wire, the same as that used in Example 1, and a block copolymerized polyimide. The average thickness (D1) of the part covering the flat part of the rectangular copper wire having the insulating layer (average thickness 17 μm) by the block copolymer polyimide and the rectangular copper wire of the block copolymerized polyimide is 15 μm, and the average thickness of the part covering the corner part A flat rectangular insulated copper wire having (D2) of 12 μm was obtained.

Comparative Example 3
128.9 g (0.4 mol) of 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride and 116.9 g (0.4 mol) of 1,3-bis- (4-aminophenoxy) benzene Dissolved in 983 g of N-methyl-2-pyrrolidone (NMP) and reacted for 10 hours at room temperature with stirring at 200 rpm using a squid type stirrer, 20% polyamic acid solution (intrinsic logarithmic viscosity of polyamic acid 0.78) Got. NMP and benzyl alcohol are added to this 20% polyamic acid solution, then a neutralizing agent is added, pure water is further added, the solid content of polyamic acid is 6.8%, NMP is 41%, benzyl alcohol is 16%, and N-methylmorpholine. An electrodeposition composition of 0.9% and pure water 35.3% was prepared. The electrodeposition composition thus obtained was electrodeposited on a copper wire having a circular cross section and a rectangular copper wire, the same as that used in Example 1 under the same conditions as in Example 1, baking, and polyimide. The average thickness (D1) of the portion covering the flat portion of the round copper wire having the insulating layer (average thickness 17 μm) and the flat copper wire of the insulating layer made of polyimide is 14 μm, and the average thickness (D2) of the portion covering the corner portion is A 12 μm flat rectangular insulated copper wire was obtained.

Comparative Example 4
A polyimide electrodeposition solution prepared in accordance with JP 2000-178481 A as a polyamide containing polysiloxane in a random copolymer is the same as that used in Example 1 under the same conditions as in Example 1. A copper wire having a circular cross section is electrodeposited on each of a copper wire and a flat copper wire, and is baked to form a circular insulating copper wire having a polyimide insulating layer (average thickness 17 μm) and a flat portion of the polyimide insulating layer flat copper wire. A flat insulated copper wire having an average thickness (D1) of the covered portion of 15 μm and an average thickness (D2) of the portion covering the corner portion of 12 μm was obtained.
The following evaluation tests were performed on the insulated copper wires produced in Example 1 and Comparative Examples 1 to 4.

(Heat resistance test)
The heat resistance was evaluated by a temperature index evaluation method based on JIS C 3003.

(Pinhole test)
Based on JIS C 3003, the presence or absence of a pinhole was investigated with respect to the insulated round copper wire (n = 5) and the insulated flat copper wire (n = 5).
If no pinholes were found in any of the 5 insulated round copper wires (30 cm length) and the 5 insulated flat copper wires (30 cm length), pass (○), 1 out of 10 However, when a pinhole was confirmed, it was determined as rejected (x).

(Flexibility test)
(1) Presence / absence of coating peeling by self-diameter winding Take three test pieces of the appropriate length from the same reel, and wind them ten times tightly so that the wires come into contact with each other around the test piece itself. The film was visually inspected for cracks where the conductor could be seen.

(2) Presence / absence of coating peeling in edgewise coil winding.
Two test pieces of about 20cm in length are taken from the same reel, and the central part is flatwise and edgewise at 180 ° while keeping it in one plane along the outer periphery of a round bar having a specified diameter. When bent, the film was visually inspected for cracks where the conductor could be seen.

(AC breakdown voltage)
The AC breakdown voltage was measured based on JIS C 3003 for the insulated round copper wire. That is, 1 cm of tin foil was wound on insulation and measured between the conductor and tin foil (n = 3). And an alternating voltage generator is connected to each board, a voltage is raised, and the short-circuited voltage is made into a breakdown voltage. A breakdown voltage of 2.0 kV or higher was accepted (◯), and a breakdown voltage of less than 2.0 kV was rejected (x).

(Insulation corner cover)
When the average thickness (D2) of the insulating layer at the corner of the cross section of the insulated rectangular copper wire is 0.8 times or more than the average thickness (D1) of the insulating layer at the flat portion, the pass (○), 0.8 times The case where it was less than was made into the disqualification (x).

It is a schematic diagram of the cross section of the flat insulated wire of this invention. It is a schematic diagram of an apparatus of an example used at the electrodeposition process of the varnish (electrodeposition liquid) in the manufacturing method of the insulated wire of this invention.

Explanation of symbols

1 Flat rectangular insulated wire 2 Conductor wire 3 Insulating layer

Claims (11)

A block copolymer polyimide containing a siloxane bond in the main chain of the polyimide and having an anionic group in the molecule, the weight average molecular weight (Mw) is 45,000 to 90,000, and the number average molecular weight (Mn) is An insulated wire comprising an electrodeposition coating of 20,000 to 40,000 block copolymerized polyimide as an insulating layer on the outer periphery of a conductor wire. The insulated wire according to claim 1, wherein the intrinsic logarithmic viscosity (25 ° C) of the block copolymerized polyimide is 5,000 to 50,000 mPa · s when the NMP (N-methyl-2-pyrrolidone) solution is 20 wt% . The siloxane bond in the main chain of the polyimide is a siloxane bond derived from a siloxane bond-containing diamine compound, and the siloxane bond-containing diamine compound is bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy). ) -1,1,3,3-tetramethyldisiloxane, and a following general formula (I) in one or more selected from the group consisting of compounds represented, according to claim 1 or 2, wherein Insulated wire.

(In the formula, each R independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxyl groups, and l and m are each independently And n represents an integer of 1 to 20.) Diamine component polyimide block copolymer is composed of siloxane bond-containing diamine compound and an aromatic diamine, tetracarboxylic dianhydride component composed of an aromatic tetracarboxylic dianhydride, according to any one of claims 1 to 3 Insulated wires. The insulated wire according to claim 4 , wherein the aromatic diamine contains at least an aromatic diaminocarboxylic acid and / or an aromatic diaminosulfonic acid. Aromatic tetracarboxylic dianhydride is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis- (3,4-dicarboxyphenyl) ether dianhydride, 3,3 ′, 4, The insulated wire according to claim 4 or 5 , comprising at least one selected from 4'-benzophenonetetracarboxylic dianhydride and 3,3 ', 4,4'-biphenylsulfonetetracarboxylic dianhydride. Cross-sectional shape of the conductor wires is rectangular-shaped, insulated wire according to any one of claims 1-6. Conductor wire is made of copper or a copper alloy, insulated wire according to any one of claims 1-7. The insulated wire according to claim 7 , wherein the thickness of the insulating coating formed on the flat surface of the outer periphery of the conductor wire is 1.5 to 30 µm.   Electrodeposition coating of block copolymerized polyimide is a solution in which water, a poor solvent for polyimide, and a neutralizing agent for making polyimide a neutralizing salt are further added to a solution obtained by dissolving the block copolymerized polyimide in an organic polar solvent. The insulated wire according to any one of claims 1 to 9, wherein the varnish is formed by electrodeposition and baking on the outer periphery of the conductor wire. Insulating coils of insulated wire were wound edgewise coil winding or alignment according to any one of claims 1-10.

Images