JP2013082760A - Insulating varnish and insulated wire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide insulating varnish with which an insulating coat (insulating coat with uniform thickness) with a shape corresponding to a shape of an opening of a die is easily formed.SOLUTION: In the insulating varnish with which an insulating coat is formed on a surface of a conductor by applying the insulating varnish on the surface of the conductor, subsequently removing excessive applied coating by passing the conductor through a die with a shape similar to the sectional shape of the conductor, and thereafter drying and baking the coat, a thixotropic property is imparted to the varnish in order to reduce viscosity when large shearing force is applied thereto, and to make the coating scarcely droop on drying and curing. The thixotropy property is imparted to the varnish by compounding an amide-based flow-controlling agent which is preferably a fatty acid amide or an oligomer thereof or a modified product or a mixture of them with the varnish.

Description

  The present invention relates to an insulating varnish used for insulating coating of electric wires, and more particularly to an insulating varnish excellent in applicability of flat electric wires.

  Insulated wires having an insulating coating on the conductor surface are generally manufactured as follows. That is, after applying an insulating varnish to the surface of the conductor (core wire), the application amount of the surface of the conductor (core wire) is adjusted by a coating die and the applied paint surface is smoothed, and then the varnish applied through a baking furnace is applied. By baking, an insulating film is formed on the conductor surface. The series of operations (insulation varnish application, application amount adjustment, and baking) is repeated a plurality of times until the insulating coating reaches a predetermined thickness.

  The coating die has an opening, and the coating amount is adjusted by removing the excess paint by passing the core wire coated with the insulating varnish through the opening. In the insulated wire, when the thickness of the insulating coating is not uniform, the electrical insulation of the insulated wire is determined by the location where the insulating coating is thin, so that the insulation may be insufficient. Therefore, it is important to make the film thickness uniform. As the application die, for example, as described in Japanese Patent Application Laid-Open No. 2008-123759 (Patent Document 1), generally, the shape of the opening when viewed in plan is substantially similar to the cross-sectional shape of the conductor. .

  By the way, as a conductor (core wire) of an insulated wire, a conductor (round wire) having a substantially circular cross section has been conventionally used. However, in recent years, the space factor is low, and various devices can be miniaturized. In view of the above, a conductor (flat conductor) wire having a substantially rectangular cross section (a flat rectangular cross section) is widely used. In this flat wire, if the thickness of the insulating coating is non-uniform, there is a risk that the wires will not be in direct contact with each other in the winding state and an unnecessary space may be formed, and there is a concern that the space factor will decrease. The For flat wires, the uniformity of the coating is important for this reason, but it is difficult to make the film thickness uniform compared to the round wire.

  That is, as shown in FIG. 1, when it is going to produce the flat electric wire which has the coating film 2 with uniform thickness in the core wire 1, the die | dye which has the opening part 3 similar to the core wire 1 is used like FIG. It will be. However, in the flat electric wire composed of the combination of the flat portion 1a and the direct lower portion 1b perpendicular to the flat portion, the paint tends to flow to the corner portion of the flat conductor due to the surface tension of the paint after passing through the die and before being cured. Thus, as shown in FIG. 3, a so-called dog-bone-shaped insulating coating in which the corners 2′a of the coating 2 ′ swell is formed.

JP 2008-123759 A

  In order to make the thickness of the insulating coating uniform, for example, in Patent Document 1 described above, a coating die having an opening in which a corner having a radius of curvature larger than the corner of the conductor is used is formed in the opening. The coating amount is adjusted so that the final value of the radius of curvature of the corner formed at the opening is larger than the initial value of the radius of curvature of the formed corner, and the insulating coating has a two-layer structure. It has been proposed to use a resin having higher extensibility than the inner amide imide resin as the amide imide resin layer.

  However, even if the shape of the die is devised, a dogbone-shaped film may be formed by changing the type of varnish, and another solution is desired in terms of versatility.

  The present invention has been made in view of such circumstances, and the object thereof is not to solve by a die, but an insulating coating having a shape corresponding to the shape of the opening of the die, that is, a uniform coating. An object of the present invention is to provide an insulating varnish that can easily form an insulating coating having a thickness.

  The present inventors have made various studies on the composition of the varnish so that an insulating film having a uniform thickness can be formed even if a general die whose opening is similar in shape to the conductor cross section is used. . Although attempts were made to increase the viscosity of the insulating varnish and reduce the fluidity, it was found that the high-viscosity varnish applied excessive tension to the conductor (core wire) when passing through the die, causing disconnection. Therefore, further investigations were made, and it was considered useful to impart thixotropic properties to reduce the viscosity when a large shear force was applied, and to prevent dripping during drying and curing, and the present invention was completed. did.

  That is, the insulating varnish of the present invention is applied to the conductor surface, and then the excess paint applied is removed by passing through a die having a shape similar to the cross-sectional shape of the conductor, and then dried and baked. An insulating varnish for forming an insulating coating on the surface contains an amide-based flow regulator.

  The amide-based flow regulator is preferably a fatty acid amide or an oligomer thereof, or a modified product or a mixture thereof, and is contained in an amount of 2 to 20 parts by mass with respect to 100 parts by mass of the film-forming resin solids. Preferably it is. The film forming resin is preferably a polyamideimide resin.

Furthermore, the insulating varnish of the present invention has a shear rate of 0.1 to 1 rpm and a viscosity of 2 to 10 Pa · s, and preferably has a viscosity of 2 Pa · s or less at a shear rate of 60 rpm. It is suitable for an insulated wire that passes at a shear rate of 100 to 10,000 s ⁻¹ .

  The insulated wire of this invention is an insulated wire which consists of a conductor and the insulating film which coat | covers the said conductor, Comprising: The said insulating film is a cured film of the said insulating varnish of this invention.

  Since the insulating varnish of the present invention has thixotropy, it is easy to flow when a high shearing force is applied such as when passing through a die, and since it is suppressed from dripping during drying and curing, it is a flat wire. However, it is possible to suppress the insulating coating from having a so-called cross-section dog bone shape.

It is sectional drawing which shows the structure of a flat insulated wire. It is sectional drawing for demonstrating the structure of the conventional die | dye used for manufacture of a flat insulated wire. It is a structure schematic cross section for demonstrating the problem of a flat insulated wire.

  Although embodiments of the present invention will be described below, it should be considered that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  In the insulated wire paint according to the present invention, after being applied to the conductor surface, the excess paint applied is removed by passing through a die having a shape similar to the cross-sectional shape of the conductor, and then the conductor surface is dried or baked. An insulating varnish that forms an insulating coating on the surface contains an amide flow regulator.

  The type of insulating varnish to which the present invention is applied, that is, the type of resin that is a film constituent component, is not particularly limited, and may be any of a dry-solidified type and a bake-hardened type. Specifically, resins conventionally used in the field of insulating varnish, such as polyamide imide resin, polyimide resin, polyester imide resin, polyamide resin, polyether sulfone resin, polyether ether ketone resin, polysulfone resin, etc. The varnish which makes a main component is mentioned. Of these, polyamideimide resin varnish is particularly preferred.

  As the insulating varnish, a main resin may be synthesized from a monomer, or a commercially available varnish may be used. For example, commercially available products of amideimide resin coatings include, for example, trade names HI-400A, HI-407A, HI-401D-24, HI-401A No. manufactured by Hitachi Chemical Co., Ltd. 1, HI-401SE-23 or the like can be used.

  As the amide flow regulator used in the present invention, those known as so-called amide waxes can be used. Specific examples include fatty acid amides or oligomers thereof, or modified products (modified polyamides) or mixtures thereof as active ingredients.

The fatty acid amide is a fatty acid amide obtained by reacting an amine and a carboxylic acid. As the amine, diamines having 2 to 6 carbon atoms such as ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane and hexamethylenediamine are preferably used. In this case, an oligomer is usually synthesized.
The aliphatic carboxylic acid may be a monocarboxylic acid having 2 to 18 carbon atoms, or a dicarboxylic acid such as oxalic acid, succinic acid, fumaric acid, glutaric acid, adipic acid, suberic acid, azelaic acid, and sebacic acid. Furthermore, fatty acids derived from natural fats and oils such as castor oil fatty acids, dimer acids obtained by polymerizing unsaturated fatty acids, and the like can be used. In the case of unsaturated carboxylic acid, it is preferable that it is hydrogenated.

The fatty acid amide oligomer as described above may be a modified one (modified polyamide) as long as it does not impair the thixotropy. The modified polyamide is obtained by modifying the molecular chain terminal portion or the inside of the molecular chain of the polyamide, whereby the polarity of the flow control agent can be adjusted. Examples of the modified polyamide include urea-modified polyamide. The rate of modification is within a range that does not impair the thixotropy imparting effect as the fatty acid amide.
As a mixture of fatty acid amides or oligomers thereof, other flow regulators are mixed within a range that does not impair thixotropy, and examples thereof include mixtures with oxidized polyolefins such as oxidized polyethylene and oxidized polypropylene.

  Those known as amide waxes as described above are usually solid at room temperature. Therefore, it is preferable to use those which are dispersed in an organic solvent such as alcohol solvents, cyclic saturated hydrocarbons, aromatic hydrocarbons, esters, etc. and made into liquid or paste form.

As the alcohol solvent, aliphatic alcohols such as methanol, ethanol, propanol and butanol, aromatic alcohols such as benzyl alcohol, ethylene glycol, monophenyl glycol and the like can be used.
Also. As the alicyclic hydrocarbon, cyclohexane, alkylcyclohexane and the like can be used.
As the aromatic hydrocarbon, xylene, toluene and the like can be used.
Examples of the esters include acetate esters such as butyl acetate, hexyl acetate and heptyl acetate; dibasic acid esters such as propionate and methyl succinate.
These organic solvents can be used alone or in combination.

  By suspending the amide wax in these organic solvents and heating it, a homogeneous solution or a paste can be obtained. By using it as a solution or paste, it becomes easy to disperse uniformly in the insulating varnish, and the fluidity of the insulating varnish can be adjusted while reducing the influence on the physical properties of the coating film.

  When a paste-like flow control agent is used, the content of the amide wax contained in the flow control agent is preferably about 5 to 30% by mass, more preferably 10 to 25% by mass.

  A commercial product may be used as the paste-like amide-based flow regulator as described above. For example, fatty acid amide paste types (6900-20X, 6900-10X, A603-20X, A603-10X, A670-20M, 6810-20X, 6850-20X, 6820-20M, 6820, commercially available from Enomoto Kasei Co., Ltd. -10M, FS-6010, PFA-131, PFA-231, F-9020, F-9030, F-9040, F-9050, etc.) and oxidized polyolefin amides (NS-5010, NS5025, NS-5210, NS-) 5310), higher fatty acid amide pastes (Tallen series such as Taren 7200-20 and Taren 7500-20) and BYK-405 manufactured by BYK Chem.

  The flow regulator as described above has a reversible binding force and brings a thickening effect to the varnish by aggregation. Furthermore, it is thought that a gentle cross-linking structure is formed by a hydrogen bond with the film-forming resin in the varnish, thereby contributing to an increase in the viscosity of the paint. On the other hand, when a strong shearing force is applied to the paint, such as when passing through a die, their bonds are gently broken, and the apparently crosslinked molecular chains of the film-forming resin are separated, resulting in an apparent viscosity. When the die passes, an excessive load is prevented from being applied to the conductive wire as the adherend, and the coating is easily smoothed. Furthermore, after passing through the die, the release of the shearing force causes the flow regulator particles to agglomerate again, thereby increasing the viscosity of the varnish and making it difficult to flow.For example, in the case of a flat rectangular conductor, It can suppress that a paint flows. Thus, thixotropic property is imparted to the varnish, and as a result, it is possible to prevent the so-called insulating coating from being formed into a dogbone shape.

  The flow regulator is blended at a ratio of 2 to 20 parts by mass, preferably 3 to 10 parts by mass as a solid (active ingredient) per 100 parts by mass of a film-forming resin (in the case of a commercially available varnish, resin solids). It is preferable. If the amount of the flow regulator is too large, the heat resistance, strength, etc. of the resin may be reduced. If the amount is too small, the effect of imparting thixotropic properties becomes insufficient.

  The flow regulator may be kneaded in the film-forming resin by dry blending or the like, or after the film-forming resin is previously diluted in an organic solvent, the flow regulator may be added and mixed. It is preferable to heat as needed so that it may mix uniformly.

  The insulating varnish of the present invention may further contain various additives such as pigments, dyes, inorganic or organic fillers, and lubricants as necessary. These additives may be added directly to the film-forming resin as the main component, may be mixed simultaneously with the flow control agent, or may be blended after the addition of the flow control agent.

  The insulating varnish of the present invention obtained as described above is usually used as a varnish having a resin solid content of about 10 to 50%. An organic solvent is used as the diluting solvent. In this case, the organic solvent of the same type as the organic solvent used for the flow regulator may be used, or a different type of organic solvent may be used.

  The insulating varnish of the present invention having the above composition has a shear rate of 0.1 to 1 rpm, a viscosity of 2 to 10 Pa · s, and a viscosity of 2 Pa · s or less when the shear rate is 60 rpm.

The insulated wire of the present invention has an insulating coating formed using the insulating varnish of the present invention.
The core wire used as the conductor is a metal wire such as a copper wire, an aluminum wire, an aluminum alloy wire, a nickel-plated copper wire, or a silver-plated copper wire. The shape of the core wire is not particularly limited, but it is particularly useful for a conductor that has been difficult to form a coating having a uniform thickness, for example, a rectangular conductor having a rectangular cross section, after the paint passes through the die.

  After being applied to the surface of the conductor by immersing it in a paint tank containing the insulating varnish of the present invention, after passing through a die to remove the excessively applied paint and smoothing the applied surface, Bake treatment. Application, die passing, and baking may be repeated twice or more. These series of treatments may be performed using a vertical facility in which the paint tank, the die, and the baking furnace are installed in this order from the bottom, or a horizontal facility in which the paint tank, the die, and the baking furnace are arranged in parallel. May be used.

The passing of the die is not particularly limited, but it is usually preferable to pass the die at a shear rate of 100 to 10,000 s ⁻¹ . Even if it passes at such a shear rate, the viscosity becomes about 1 to 5 Pa · s due to the thixotropy imparting effect of the flow regulator, and it is possible to prevent an excessive shear force from being applied to the core wire.

  What is necessary is just to select suitably the baking temperature and time of an insulating varnish according to the kind of film formation resin which is a main component. For example, in the case of a polyamide-imide varnish, it is preferably performed by passing through a furnace at about 350 to 500 ° C. for 5 to 10 seconds per pass.

  The thickness of the insulating coating is preferably 1 to 100 μm, more preferably 10 to 50 μm from the viewpoint of protecting the conductor. By repeating application and baking, a thick insulating film can be formed, and even with a thick film, the uniformity of the film can be ensured.

The insulating film formed of the insulating varnish of the present invention may be formed directly on the conductor, or a base layer may first be formed on the conductor surface, and a polyamide-imide resin insulating film may be formed thereon. .
Examples of the underlayer include insulating films formed by applying and baking various conventionally known insulating paints such as polyurethane, polyester, polyesterimide, polyesteramideimide, polyamideimide, polyimide, and the like.

  Furthermore, you may provide an overcoat layer in the upper layer of the insulating film formed using the insulating varnish of this invention. In particular, by providing a surface lubrication layer for imparting lubricity to the outer surface of an insulated wire, the stress generated by the friction between the wires during coil winding and compression processing to increase the space factor, and by this stress This is preferable because damage to the insulating coating can be reduced. The resin constituting the topcoat layer may be any resin having lubricity, for example, paraffins such as liquid paraffin and solid paraffin, various waxes, polyethylene, fluororesin, silicone resin and other lubricants with a binder resin. There may be mentioned a bound one. Preferably, an amidoimide resin imparted with lubricity by adding paraffin or wax is used.

  The best mode for carrying out the present invention will be described with reference to examples. The examples are not intended to limit the scope of the invention.

[Measurement evaluation method]
First, the evaluation method performed in this example will be described.
(1) Viscosity Using a rheometer, the viscosity (Pa · s) was measured for each of shear rates of 0.1 rpm, 1 rpm, 6 rpm, and 60 rpm.

(2) Flexibility of electric wire It tested based on JIS C3003 7.1.1 flexibility test. After the insulated wire was stretched by 10%, 20%, and 30% with respect to the initial length, cracking and peeling of the insulating coating were observed when the insulated wire was wound along the outer shape of a round bar having a diameter of 1 mm. About 30 insulated wires, the said flexibility test was done and the number which the crack, peeling, etc. produced was counted.

(3) Sheath removal test The conductor (copper wire) is removed from the insulated wire by etching, and the remaining insulation coating is subjected to a tensile test under predetermined conditions (chuck interval 2 cm, tensile speed 10 mm / min) using a tensile tester. The following items were measured.
-Elongation at break (%): Elongation of coating at break-Tensile strength (MPa): (tensile load) at break / (cross-sectional area of coating).
-Tensile elastic modulus (GPa): It calculated | required as the maximum inclination of the curve (SS curve) obtained by the graph of tensile load vs elongation.
Break energy (mJ): Determined as the area of the figure drawn by the SS curve.

(4) Abrasion resistance (N)
The unidirectional wear value (g) was measured in accordance with the wear resistance test described in JIS C3003-1999.

(5) Softening temperature (° C)
The glass transition point was measured by a dynamic viscoelasticity (DMS) measuring device, and this was used as the softening temperature.

[Polyamideimide resin varnish No. Preparation of 1-5 and production and evaluation of insulated wires]
With respect to 100 parts by mass of polyamide imide resin varnish “AE2-27” manufactured by Hitachi Chemical Co., Ltd., the amount of the flow control agent shown below was added in the amount shown in Table 1, and polyamide imide insulating varnish No. 1 was added. 1-5 were prepared and the viscosity in each varnish was measured. For comparison, Table 1 shows the results of measuring the viscosity in the same manner even when the flow regulator was not added (polyamideimide resin varnish “AE2-27” alone). In addition, the addition amount of the flow control agent in Table 1 indicates the amount of the active ingredient (fatty acid amide, or fatty acid amide and oxidized polyolefin, or modified urea) in the flow control agent with respect to 100 parts by mass of the varnish resin solid content.

The flow regulator used is as follows.
Fatty acid amide flow control agent a: “6900-10X” manufactured by Enomoto Kasei. This is a paste-like flow regulator using ethyl alcohol and methyl alcohol as the other organic solvent by pre-swelling the fatty acid amide as the active ingredient in xylene, and the active ingredient (fatty acid amide) content is 10%. )is there.
Fatty acid amide flow control agent b: “6900-20X” manufactured by Enomoto Kasei. “6900-10X” has a different active ingredient content and a fatty acid amide content of 20%.
Modified polyamide-based flow regulator: “BYK-431” manufactured by Big Chemie was used. This is a solution of a high molecular weight urea-modified low-polarity polyamide using isobutanol and monophenyl glycol (90/10 mixture) as solvents. The content of urea-modified polyamide as an active ingredient is 25%.
-Fatty acid amide-oxidized polyolefin mixed flow control agent: “LS-5210” manufactured by Enomoto Kasei. The content of the fatty acid amide-oxidized polyolefin mixture as an active ingredient is 10% and is a paste dispersed in xylene, ethyl alcohol, and isopropyl alcohol.
-Modified urea type flow regulator: "BYK-410" manufactured by Big Chemie was used. This is an N-methylpyrrolidone solution (modified urea content 52%) of modified urea (active ingredient) having polar groups compatible with the binder between and at the ends of the urea groups.

It was confirmed that thixotropy was imparted to the round-shaped conductor having a conductor diameter of 0.990 mm using the vertical coating equipment, among the insulating varnishes prepared above. 1-4, and insulating varnish No. to which no flow regulator was added. 6 was used to produce an insulated wire.
Insulated wires are manufactured by dipping in each insulating varnish, then passing through a die having an opening similar to the conductor at a speed of 3.5 m / min, passing through a baking furnace, and baking at 350 ° C. for 1 minute. And an insulating film was formed. By repeating this application of the insulating varnish, passing through a die, and baking 8 times, an insulated wire having an insulating coating having a thickness as shown in Table 1 was created. About the produced insulated wire, flexibility, elongation, tensile strength, elastic modulus, breaking energy, unidirectional wear, and softening temperature were measured based on the above evaluation methods. The results are shown in Table 1.
In addition, No. For No. 6, a round conductor having a diameter of 1.017 mm was used.

  Insulating varnish No. of Example of the present invention containing a flow regulator. 1-4, the viscosity is 2 Pa · s or more at a shear rate of 0.1 rpm or less, whereas the viscosity decreases to 1.7 Pa · s or less at a shear rate of 60 rpm or more, thereby providing thixotropic properties. You can see that In addition, the degree of thixotropic properties (high viscosity when loaded with low shear force and low viscosity when loaded with high shear force) is the highest in fatty acid amide content. 1 and 2 were large, and the mixture type (No. 4) and the modified type (No. 3) tended to be small.

  On the other hand, insulating varnish No. 1 containing a modified urea-based flow regulator. No. 5 shows that the viscosity is low when the shear rate is low, the viscosity of the varnish increases as the shear rate increases, and no thixotropic property is imparted. Furthermore, the degree of increase in viscosity accompanying the increase in shear rate is the same as in the case of the polyamideimide resin varnish alone containing no flow regulator. It was bigger than 6. This is because the urea group has a smaller hydrogen bonding effect on the paint component than the amide group. Especially for polyamide-imide resins, it does not easily form an associated molecule due to hydrogen bonding, and it also aggregates between the modified urea flow regulators. It is presumed that it was because of this. In this respect, No. 1 using a urea-modified polyamide flow control agent. In No. 3, since the content ratio of the urea-modified portion is small, it is presumed that aggregation was not performed and thixotropy was not hindered.

  Insulating varnish No. containing no flow regulator 6 had a viscosity of 1.76 Pa · s or less at a shear rate of 0.1 rpm, whereas the viscosity increased to 2.57 Pa · s at a shear rate of 60 rpm, and the shear force increased with an increase in the shear rate. It can be seen that it increases. Therefore, it is expected that increasing the shear rate will increase the effect on the physical properties of the film.

In addition, No. which added the amide type flow regulator to the varnish. In 1-4, the influence which it has on the physical property of an insulating film was hardly recognized. It can be seen that the addition of about 5 parts by mass of the amide-based flow regulator per 100 parts by mass of the varnish resin solids does not affect the physical properties of the insulating coating.
Therefore, the inclusion of the amide flow regulator makes it easy to achieve uniform thickness of the coating by passing through a die without affecting the physical properties of the insulating coating.

  Since the insulating varnish of the present invention is provided with thixotropy by blending a flow regulator, it is generally difficult to uniformly adjust the film thickness by adjusting the coating amount by passing through a die. Also in the formation of the insulating film, a highly uniform insulating film can be formed using a die having a shape similar to that of a conductor and a coating facility, which is useful in the field of manufacturing insulated wires.

1 Conductor (core wire)
2, 2 'insulation coating 3 opening

Claims (7)

Insulating varnish that forms an insulating film on the conductor surface after being applied to the surface of the conductor and then removed by passing through a die having a shape similar to the cross-sectional shape of the conductor, followed by drying and baking. An insulating varnish characterized by containing an amide-based flow regulator. The insulating varnish according to claim 1, wherein the amide-based flow regulator is a fatty acid amide or an oligomer thereof, or a modified product or a mixture thereof. The insulating varnish according to any one of claims 1 to 3, wherein the amide-based flow regulator is contained in an amount of 2 to 20 parts by mass with respect to 100 parts by mass of the film-forming resin solid content. The insulating varnish according to any one of claims 1 to 4, wherein the die passes through at a shear rate of 100 to 10,000 s- ¹ . The insulating varnish according to any one of claims 1 to 5, which has a viscosity of 2 to 10 Pa · s at a shear rate of 0.1 to 1 rpm and a viscosity of 2 Pa · s or less at a shear rate of 60 rpm. The insulating varnish according to any one of claims 1 to 6, wherein the film-forming resin is a polyamide-imide resin. An insulated wire comprising a conductor and an insulating coating covering the conductor,
The insulated wire in which the said insulating film has the cured film of the insulating varnish of any one of Claims 1-7.

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