JP5503121B2 - Insulating paint and insulated wires - Google Patents

Description

  The present invention relates to an insulating paint and an insulated wire. In particular, the present invention relates to a polyamide-imide insulating wire and a polyamide-imide insulating wire formed by applying and baking the insulating coating on a conductor.

Insulated electric wires obtained by applying and baking electrical insulating paints on conductors are used in large quantities for coils used in various electric devices. Electrical insulation paints are divided into heat-resistant classes with a heat-resistant temperature of 105 ° C to 250 ° C depending on various applications and required performance. Among them, polyamide-imide insulating paints have excellent heat resistance, mechanical properties, and refrigerant resistance. In recent years, it has been widely used in motors of a heat resistance class having a heat resistance temperature of 180 to 200 ° C. or higher. In addition, in order to rationalize the production of insulated wires coated and baked with polyamide-imide insulating paint, the insulating paint is strongly required to have high temperature and high-speed bakeability corresponding to the production rationalization of the baking process.

However, conventional polyamide-imide insulating coatings are inferior in high-temperature and high-speed bakeability compared to polyester-based insulating coatings and polyesterimide-based insulating coatings having a heat resistance grade of 155 to 180 ° C. There was a drawback that wrinkles and other abnormalities were likely to occur. In particular, polyamideimide insulation coatings with improved adhesion to conductors are difficult to be baked at high temperature and high speed. In the baking process, low temperature and low speed are used to prevent wrinkle defects, and the amount of coating per application is reduced. For example, an insulated wire is manufactured by increasing the number of times, and it is forced to manufacture under a disadvantageous condition in terms of cost.

  In the above problems, foaming during baking depends on the generation of carbon dioxide gas generated during the curing reaction of the polyamideimide resin and the solvent evaporation behavior during baking. The wrinkle of the film depends on the speed of the curing reaction.

Therefore, Patent Document 1 describes that a specific epoxy resin is blended with a polyamide-imide resin in order to reduce generation of carbon dioxide gas and prevent foaming of the film. As a result, the terminal isocyanate group of the polyamideimide resin and the epoxy ring preferentially react to weaken the reaction of the terminal carboxyl group and terminal isocyanate group and the amide group and carboxyl group, which is the curing reaction of the original amideimide resin. Is suppressed. Further, as a similar proposal of Patent Document 1, Patent Document 2 describes that blending an epoxy resin having an epoxy equivalent of 400 or less in a polyamide-imide insulating paint suppresses foaming at the time of high-speed baking and does not deteriorate electric wire characteristics. ing.

In Patent Document 3, in order to prevent wrinkling of the film by adjusting the curing reaction rate, a proposal has been made to mix a metal salt of a specific element in a polyamide-imide insulating coating. This is because a phenolic solvent (representative example cresol) is used as the organic solvent, so that the curing reaction by the terminal isocyanate group of the polyamide-imide resin is more than when an aprotic solvent (representative example N-methyl-2-pyrrolidone) is used. It is a proposal to improve the disadvantage that it is difficult to occur. According to this proposal, the metal salt serves as a catalyst for activating the terminal isocyanate group stabilized with the phenol solvent, and the wrinkle and roughness of the film are eliminated by improving the curing rate.

  In addition, Patent Document 4 describes that a specific high-boiling hydrocarbon is blended in the insulating paint in order to prevent the foam of the film by adjusting the solvent evaporation rate. The high boiling point solvent remains in the process, so that the film surface hardening is suppressed and foaming is reduced.

Japanese Patent Laid-Open No. 05-339522 Japanese Unexamined Patent Publication No. 07-216058 JP-A-55-139451 Japanese Unexamined Patent Publication No. 57-096063

However, the techniques described in Patent Documents 1 and 2 have a problem that the heat resistance of the insulating film after baking is inferior to that of the conventional polyamideimide insulating paint, and in particular, the softening characteristics of the insulated wire are lowered. Moreover, in the technique of patent document 3, there exists a problem that the baking workability | operativity falls because it reacts with a polyamide-imide resin depending on the kind of metal salt, and an insulating coating material raises, and the technique of patent document 4 is changed to a polyamide-imide resin. When applied, there is a problem that the compounding amount is limited due to low compatibility with the resin, and the inherent effect of preventing surface hardening cannot be exhibited due to the low fluidity of the resin during coating.

The present invention has been made in view of such conventional problems, and an object thereof is to provide an insulating paint and an insulated wire having good adhesion to a conductor and good appearance even when baked at high temperature and high speed. There is to do.

In order to solve the above-mentioned problems, a first aspect of the present invention provides an insulating paint characterized in that a polyamide-imide resin is dissolved in an organic solvent containing 1,3-dimethyl-2-imidazolidinone. .

The first aspect of the present invention is the following (1) and (2).

(1) An insulating paint in which a polyamideimide resin is dissolved in an organic solvent,
  The organic solvent comprises N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone;
The content of the 1,3-dimethyl-2-imidazolidinone in the organic solvent is 10% by mass to 30% by mass,
A weight average molecular weight of the polyamideimide resin is 20000 or more and 30000 or less.

(2) For 100 parts by weight of the polyamideimide resin,
(I) 5-20 parts by weight of alkoxylated melamine resin,
(Ii) 0.05 to 1.0 part by weight of a trialkylamine, or
(Iii) 0.05 to 1.0 part by weight of a trialkylamine and 5 to 20 parts by weight of an alkoxylated melamine resin,
Is further contained, The insulating paint as described in (1) characterized by the above-mentioned.

The second aspect of the present invention is the following (3).
(3) (1) or insulated electric wire insulating paint, characterized in that formed by coating baked or via another insulating layer on a conductor according to (2).

According to the present invention, it is possible to provide an insulating paint and an insulated wire having good adhesion to a conductor and good appearance even when baked at high temperature and high speed.

  The insulating paint of the present invention is an insulating paint obtained by dissolving a polyamideimide resin in an organic solvent, and is characterized in that 1,3-dimethyl-2-imidazolidinone is contained in the organic solvent. By containing 1,3-dimethyl-2-imidazolidinone in the organic solvent, a smooth insulating film free from foaming and wrinkles can be obtained.

FIG. 1 shows the results of thermogravimetric analysis regarding the insulating paint of the present invention and the conventional insulating paint. The vertical axis represents the weight reduction rate of the insulating paint, and the horizontal axis represents the temperature of the heating atmosphere. From this result, in the temperature range of 50 to 120 ° C., which is estimated as the linear temperature at which the solvent evaporates in the baking furnace, the solvent evaporation rate of the insulating paint of the present invention (indicated by ▲) is the conventional insulating material (indicated by ◆). ) You can see it is slower. The paint exhibiting such a behavior remarkably hinders the surface hardening of the film and suppresses foaming. In other words, since 1,3-dimethyl-2-imidazolidinone has a high boiling point and good compatibility with the resin, a high boiling point 1, It is thought that 3-dimethyl-2-imidazolidinone remains and this prevents the surface hardening of the film.

As described above, 1,3-dimethyl-2-imidazolidinone plays a major role in suppressing foaming, and is between 10% by mass and 30% by mass with respect to the total amount of solvent of the insulating paint in the present invention. rather it preferably is at, in the present invention, use 10% to 30% by weight.

When 1,3-dimethyl-2-imidazolidinone is less than 10% by mass, foaming and tubing are likely to occur, and when it exceeds 30% by mass, the viscosity of the insulating paint increases, so the workability during baking is reduced. Enamel wire quality defects are likely to occur.

There is no restriction | limiting in particular in the manufacturing method of the polyamide-imide resin in this invention, It can manufacture by an already well-known manufacturing method (Japanese Patent Publication 44-19274 etc.). Specifically, it can be obtained by reacting an aromatic tricarboxylic acid anhydride and an aromatic diisocyanate in an aprotic polar solvent. A representative example of the aromatic tricarboxylic acid anhydride is trimellitic acid anhydride.

In addition, if necessary, a part of this aromatic tricarboxylic anhydride may be an aromatic tetracarboxylic dianhydride such as pyromellitic dianhydride or benzophenone tetracarboxylic dianhydride or terephthalic acid or isophthalic acid. An aromatic dibasic acid may be substituted.

In addition, there is no restriction | limiting in the mixing | blending time of 1, 3- dimethyl-2- imidazolidinone, You may charge at the time of the reaction start as a resin synthetic | combination solvent of a polyamide-imide insulation coating material, and you may use as a diluent at the time of completion | finish of reaction.

As the aromatic diisocyanate, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, 4,4'-diphenyl ether diisocyanate and the like can be used, but 4,4'-diphenylmethane diisocyanate is preferable from the viewpoint of cost and availability.

In the reaction of the aromatic tricarboxylic acid anhydride and the aromatic diisocyanate, the aromatic diisocyanate is preferably set between 0.9 mol and 1.1 mol with respect to 1 mol of the aromatic tricarboxylic acid anhydride. More preferably, the number of moles of the aromatic diisocyanate is set between 1.0 mole and 1.05 mole. By setting in this way, the high molecular weight polyamideimide resin of the present invention is obtained. The reaction proceeds with heat condensation while removing carbon dioxide gas liberated in the presence of an aprotic polar solvent between 80 ° C. and 150 ° C. out of the system.

As the aprotic polar solvent, N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide and the like can be used . In the present invention, N-methyl-2-pyrrolidone is used. that use.

The weight average molecular weight of the polyamide-imide resin used in the present invention, rather preferably be 20,000 or more and 30,000 or less, the present invention is 20,000 or more and 30000 or less.

The molecular weight of the polyamideimide resin is controlled by replacing the viscosity and the motor torque value of the stirrer with each other because the viscosity of the paint increases with time. In the present invention, when the weight average molecular weight falls between 20,000 and 30,000, heating is stopped, and the reaction is stopped by adding a diluting solvent, whereby the preferred weight average molecular weight of the polyamideimide resin can be obtained. In addition, alcohol, phenol, lactam, etc. which protect the isocyanate group of the resin terminal can also be added as a reaction terminator.

If the weight average molecular weight of the polyamide-imide resin is smaller than 20000, the number of isocyanate groups at the end of the resin per unit weight will increase, and the amount of carbon dioxide generated by the reaction with the carboxyl group at the end of the resin will increase. Foaming is likely to occur. On the other hand, if the molecular weight exceeds 30000, the number of isocyanate groups at the end of the resin relative to the unit weight will be too small, curing during baking will not proceed sufficiently, and electrical characteristics such as insulation will tend to be reduced. Furthermore, there arises a problem that the viscosity of the insulating paint becomes too high and the baking workability is lowered.

N, N-dimethylformamide (DMF) or high-boiling hydrocarbons (for example, Hysol 1000, Hysol manufactured by Maruzen Petrochemical Co., Ltd.) are used as cosolvents to reduce the viscosity and cost of insulating coatings within the range where foaming and wrinkles do not occur. 1500 (trade name)) and xylene can also be used. In particular, since DMF can lower the viscosity of the insulating paint, it can be used for a general purpose as a co-solvent.

Moreover, a trialkylamine and / or alkoxylated melamine resin can be mix | blended. The trialkylamine is preferably a lower alkyl trialkylamine such as trimethylamine, triethylamine, tripropylamine or tributylamine. Among these, trimethylamine and triethylamine are more preferable in terms of flexibility and adhesion. In addition, as the alkoxylated melamine resin, for example, a melamine resin substituted with a lower alkoxy group such as a butoxylated melamine resin or a methoxylated melamine resin can be used, and a methoxylated melamine resin is preferable in terms of compatibility of the resin. These have the effect of improving the adhesion between the polyamideimide resin and copper.

  Here, it is preferable that a trialkylamine is 0.05-1.0 weight part with respect to 100 weight part of polyamideimide resins. When the amount is less than 0.05 part by weight, sufficient adhesion cannot be obtained, and when it exceeds 1.0 part by weight, the stability as a coating is lowered. Moreover, it is preferable that an alkoxylated melamine resin is 5-20 weight part with respect to 100 weight part of polyamideimide resins. When the amount is less than 5 parts by weight, sufficient adhesion cannot be obtained. When the amount exceeds 20 parts by weight, the heat resistance of the obtained insulated wire is lowered.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples.

In addition, the following various characteristic evaluation was performed about the obtained insulating coating material and the insulated wire.

[Insulating paint]
(A) Weight average molecular weight Using a CR type high performance liquid chromatograph manufactured by Shimadzu Corporation, the weight average molecular weight was calculated based on standard polystyrene from a molecular weight distribution curve measured using N-methyl-pyrrolidone as a developing solvent.
(B) Paint viscosity It measured according to the viscosity measurement of JISC 2351 (varnish for enameled wire). The rotating cone of the viscometer used NO3.

[Insulated wire]
(C) Appearance JIS C3003 (1984 version). The film was observed for foaming and wrinkles by the method shown in FIG. The evaluation criteria are shown below.
○: Foaming and wrinkles are not observed Δ: Foaming and wrinkles are partially generated ×: Foaming and wrinkles are continuously generated in the line (d) Dielectric breakdown voltage JIS C3003 (1984 version). 11 (2).
(E) Ascending softening JIS C3003 (1984 version). 12 (2).
(F) Flexibility After extending the wire by 20%, it was wound around a mandrel having a diameter corresponding to the conductor diameter, and the presence or absence of cracks was observed.
(G) Adhesiveness (number of twist peels)
This was performed in accordance with JIS C3003 (1999 edition) adhesion and torsion method. The length of the line was 15 cm.
(H) Workability The state of the coated dies was observed during the production of the insulated wire, and the number of dies in contact with the bar installed in the dies holder was measured out of the total number of dies coated. The evaluation criteria are shown below.
○: The ratio of the number of dies in contact with the bar is less than 10% of the whole. △: The ratio of the number of dies in contact with the bar is 10% or more and less than 60% of the whole. More than 60% of the total

As an example of the present invention, an insulating paint and an insulated wire were obtained as follows.

(Example 1-1)
Use a 2-liter 4-neck flask equipped with a stirrer, cooling tube, and calcium chloride tube. First, 192 g of trimellitic anhydride as an aromatic tricarboxylic acid anhydride, 250 g of 4,4′-diphenylmethane diisocyanate as an aromatic diisocyanate, and 540 g of N-methyl-2-pyrrolidone (NMP) as an aprotic polar solvent Charged to a three-necked flask, heated at 80 ° C. for 2 hours and reacted at 140 ° C. for 5 hours. When the viscosity in the system increased and the weight average molecular weight reached 21000, the heating was stopped and the internal temperature was increased to 80 ° C. Cooled until.
Thereafter, 231 g of 1,3-dimethyl-2-imidazolidinone (DMI) as a diluting solvent was added and stirred for about 1 hour to obtain a target polyamideimide insulating paint. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.7 times that of Comparative Example 1 shown later.

(Example 1-2)
Synthesis was carried out in the same manner as in Example 1-1 except that 115 g of NMP as an aprotic polar solvent and 116 g of DMI as a diluting solvent were added to obtain a target polyamideimide insulating paint. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.7 times that of Comparative Example 1 shown later.

(Example 1-3)
A polyamide-imide insulated wire having a film thickness of 0.030 mm was obtained in the same manner as in Example 1 except that the insulating paint of Example 1-1 was used and the number of baking coatings was six. The baking speed was 1.3 times that of Comparative Example 1 shown later.

(Example 1-4)
A polyamide-imide insulated wire having a film thickness of 0.030 mm was obtained in the same manner as in Example 2 except that the insulating paint of Example 1-2 was used and the number of baking coatings was changed to 6. The baking speed was 1.3 times that of Comparative Example 1 shown later.

(Examples 1-5 and 1-6)
The synthesis was carried out in the same procedure as in Example 1-1, and when the weight average molecular weight reached 25000 and 29000, the heating was stopped and the internal temperature was cooled to 80 ° C. to obtain the intended polyamideimide insulating paint. . Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.7 times that of Comparative Example 1 shown later.

(Example 1-7)
The target polyamideimide insulation was synthesized in the same manner as in Example 1-1 except that 617 g of NMP was added as an aprotic polar solvent and 154 g of 1,3-dimethyl-2-imidazolidinone (DMI) was added as a diluent solvent. A paint was obtained. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.7 times that of Comparative Example 1 shown later.

(Example 1-8)
The target polyamideimide insulation was synthesized in the same manner as in Example 1-1 except that 578 g of NMP as an aprotic polar solvent and 193 g of 1,3-dimethyl-2-imidazolidinone (DMI) as a diluting solvent were added. A paint was obtained. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.7 times that of Comparative Example 1 shown later.

( Reference example a )
An apparatus equipped with a stirrer, a condenser tube, and a calcium chloride tube in a two-liter four-necked flask is used. First, 192 g of trimellitic anhydride as an aromatic tricarboxylic acid anhydride, 250 g of 4,4′-diphenylmethane diisocyanate as an aromatic diisocyanate, and 40 g of NMP as an aprotic polar solvent were charged into a four-necked flask and heated at 80 ° C. for 2 hours. The temperature was raised and the reaction was carried out at 140 ° C. for 5 hours. When the viscosity in the system increased and the weight average molecular weight reached between 15000 and 18000, the heating was stopped and the internal temperature was cooled to 80 ° C.
Thereafter, 231 g of DMI was added as a diluent solvent and stirred for about 1 hour to obtain a target polyamideimide insulating paint. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.7 times that of Comparative Example 1 shown later.

( Reference example b )
The polyamideimide insulating paint of Reference Example a was applied 6 times using a vertical baking machine having a furnace length of 8 m to obtain a polyamideimide insulated wire having a one-side film thickness of 0.030 mm. The baking speed was 1.3 times that of Comparative Example 1 shown later.

( Reference example c )
An apparatus equipped with a stirrer, a condenser tube, and a calcium chloride tube in a two-liter four-necked flask is used. First, 192 g of trimellitic anhydride as an aromatic tricarboxylic acid anhydride, 250 g of 4,4′-diphenylmethane diisocyanate as an aromatic diisocyanate, and 540 g of NMP as an aprotic polar solvent were charged and heated at 80 ° C. for 2 hours to 140 The reaction was carried out at 5 ° C. for 5 hours. When the viscosity in the system increased and the weight average molecular weight reached between 30,000 and 40,000, the heating was stopped and the internal temperature was cooled to 80 ° C. 231 g of DMI was added as a diluting solvent and stirred for about 1 hour to obtain a target polyamideimide insulating paint. This polyamide-imide insulating paint was applied six times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulated wire having a one-side film thickness of 0.030 mm. The baking speed was 1.3 times that of Comparative Example 1 shown later.

( Reference example d )
An apparatus equipped with a stirrer, a condenser tube, and a calcium chloride tube in a two-liter four-necked flask is used. First, 192 g of trimellitic anhydride as aromatic tricarboxylic acid anhydride, 250 g of 4,4′-diphenylmethane diisocyanate as aromatic diisocyanate, NMP463 g and 77 g of DMI as aprotic polar solvents were charged, and the temperature was raised at 80 ° C. for 2 hours. Then, the reaction was carried out at 140 ° C. for 5 hours. When the viscosity in the system increased and the weight average molecular weight reached between 20000 and 30000, the heating was stopped and the internal temperature was cooled to 80 ° C. 231 g of DMI was added as a diluting solvent and stirred for about 1 hour to obtain a target polyamideimide insulating paint. This polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulated wire having a one-side film thickness of 0.030 mm. The baking speed was 1.7 times that of Comparative Example 1 shown later.

( Reference example e )
Synthesis was carried out in the same manner as in Example 1-12 except that 540 g of NMP was added as an aprotic polar solvent, 38.55 g of DMI and 192.45 g of NMP were added as diluent solvents, to obtain a target polyamideimide insulating paint. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.7 times that of Comparative Example 1 shown later.

(Example 2-1)
To the polyamideimide insulating paint synthesized in the same manner as in Example 1-1, commercially available Nikalac MX-10 (trade name) manufactured by Sanwa Chemical Co., Ltd. as an alkoxylated melamine resin was added to 7 parts by weight of polyamideimide resin. By adding parts by weight, the desired polyamide-imide insulating coating was obtained. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-2)
Synthesis was carried out in the same manner as in Example 2-1, except that 10 parts by weight of commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin was added to 100 parts by weight of the polyamideimide resin. A paint was obtained. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-3)
Synthesis was performed in the same manner as in Example 2-1, except that 18 parts by weight of commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin was added to 100 parts by weight of polyamideimide resin, and the target polyamideimide insulation was obtained. A paint was obtained. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-4)
0.08 parts by weight of trimethylamine, which is a typical example of trialkylamine, is added to 100 parts by weight of the polyamideimide resin to the polyamideimide insulating paint synthesized in the same manner as in Example 1-1, and the target polyamideimide is added. An insulating paint was obtained. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-5)
Synthesis was performed in the same manner as in Example 2-4 except that 0.5 part by weight of trimethylamine as a trialkylamine was added to 100 parts by weight of the polyamideimide resin to obtain a target polyamideimide insulating paint. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-6)
Synthesis was performed in the same manner as in Example 2-4 except that 0.9 part by weight of trimethylamine as a trialkylamine was added to 100 parts by weight of the polyamideimide resin, to obtain a target polyamideimide insulating paint. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-7)
In addition to the polyamide-imide insulating paint synthesized in the same manner as in Example 1-1, 10 parts by weight of a commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin with respect to 100 parts by weight of the polyamide-imide resin as a trialkylamine 0.5 parts by weight of trimethylamine was added to obtain a polyamideimide insulating paint which is the target adhesion improving type. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-8)
In addition to the polyamideimide insulating paint synthesized in the same manner as in Example 1-1, 18 parts by weight of a commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin with respect to 100 parts by weight of the polyamideimide resin as a trialkylamine 0.5 parts by weight of trimethylamine was added to obtain a polyamideimide insulating paint which is the target adhesion improving type. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-9)
In addition to the polyamide-imide insulating paint synthesized in the same manner as in Example 1-1, 10 parts by weight of a commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin with respect to 100 parts by weight of the polyamide-imide resin as a trialkylamine 0.9 parts by weight of trimethylamine was added to obtain a polyamideimide insulating coating which is the target improved adhesion type. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-10)
To the polyamide-imide insulating paint synthesized in the same manner as in Example 2, 10 parts by weight of commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin with respect to 100 parts by weight of polyamide-imide resin, and trimethylamine as trialkylamine. 0.5 part by weight was added to obtain a polyamideimide insulating paint which is a target adhesion improving type. This polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulated wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-11)
Synthesis was performed in the same manner as in Example 2-1, except that 3 parts by weight of commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin was added to 100 parts by weight of polyamideimide resin. A paint was obtained. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-12)
Synthesis was carried out in the same manner as in Example 2-1, except that 25 parts by weight of commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin was added to 100 parts by weight of the polyamideimide resin. A paint was obtained. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-13)
Synthesis was performed in the same manner as in Example 2-4 except that 0.02 part by weight of trimethylamine as a trialkylamine was added with respect to 100 parts by weight of the polyamideimide resin, to obtain a target polyamideimide insulating paint. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-14)
Synthesis was performed in the same manner as in Example 2-4 except that 1.5 parts by weight of trimethylamine as a trialkylamine was added with respect to 100 parts by weight of the polyamideimide resin, to obtain a target polyamideimide insulating paint. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-15)
In addition to the polyamide-imide insulating paint synthesized in the same manner as Example 1-1, 25 parts by weight of a commercially available Nicarak MX-10 (trade name) as an alkoxylated melamine resin with respect to 100 parts by weight of the polyamide-imide resin as a trialkylamine 0.9 parts by weight of trimethylamine was added to obtain a target polyamideimide insulating coating. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

(Example 2-16)
In addition to the polyamideimide insulating paint synthesized in the same manner as in Example 1-1, 7 parts by weight of a commercially available Nicarak MX-10 (trade name) as an alkoxylated melamine resin with respect to 100 parts by weight of the polyamideimide resin as a trialkylamine Trimethylamine was added in an amount of 0.07 parts by weight to obtain a target polyamideimide insulating coating. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

( Reference example f )
Reference Example A polyamideimide insulating paint synthesized in the same manner as in a . Further, commercially available Nicalak MX-10 (trade name) as an alkoxylated melamine resin is 10 parts by weight with respect to 100 parts by weight of polyamideimide resin, and trimethylamine as trialkylamine. 0.5 part by weight was added to obtain a polyamideimide insulating paint which is a target adhesion improving type. This polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulated wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

( Reference example g )
Reference Example In addition to the polyamideimide insulating paint synthesized in the same manner as c , 10 parts by weight of commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin with respect to 100 parts by weight of polyamideimide resin, and trimethylamine as trialkylamine. 0.5 part by weight was added to obtain a polyamideimide insulating paint which is a target adhesion improving type. This polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulated wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1 shown later.

Moreover, the insulating paint and the insulated wire as a comparative example were obtained as follows.

(Comparative Example 1)
A polyamideimide insulating paint was obtained in the same manner as in Example 1 except that 540 g of NMP was added as a reaction solvent, the polymerization reaction was continued until a predetermined molecular weight was reached, and 231 g of NMP was added as a dilution solvent. Further, this polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulating wire having a one-side film thickness of 0.030 mm.

(Comparative Example 2)
The polyamide-imide insulating paint of Comparative Example 1 was applied 8 times using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulated wire having a one-side film thickness of 0.030 mm. The baking speed was 1.3 times that of Comparative Example 1.

(Comparative Example 3)
The polyamide-imide insulating paint of Comparative Example 1 was applied 8 times using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulated wire having a one-side film thickness of 0.030 mm. The baking speed was 1.7 times that of Comparative Example 1.

(Comparative Example 4)
To the polyamideimide insulating paint synthesized in the same manner as in Comparative Example 1, further commercially available Nicalac MX-10 (trade name) as an alkoxylated melamine resin is 10 parts by weight with respect to 100 parts by weight of the polyamideimide resin, and trimethylamine as trialkylamine. 0.5 part by weight was added to obtain a polyamideimide insulating paint which is a target adhesion improving type. This polyamide-imide insulating coating was applied eight times on a 1.0 mmφ copper wire using a vertical baking machine having a furnace length of 8 m to obtain a polyamide-imide insulated wire having a one-side film thickness of 0.030 mm. The baking speed was 1.5 times that of Comparative Example 1.

The baking speed ratio when the polyamideimide insulated wires of the above Examples and Comparative Examples are manufactured is shown as a speed ratio when the proper baking speed of Comparative Example 1 is 1.0.

  The characteristics of the insulating paint and the insulated wire thus obtained were investigated, and the results obtained are shown in Tables 1 to 3.

  As shown in Comparative Examples 1 to 4 in Table 3, when 1,3-dimethyl-2-imidazolidinone (DMI) is not contained in the insulating coating, the overall appearance is not preferable. Specifically, as in Comparative Examples 1 and 2, when the linear velocity is low, the appearance is relatively favorable, but the value of the dielectric breakdown voltage is low, and the insulation property is poor. I understand. It can also be seen that when the linear velocity is increased, the appearance deteriorates.

On the other hand, 1,3-dimethyl-2 Example 1-1～1- 8 of Table 1 containing imidazolidinone, Example 2-1～2- 16 in Table 2, raised linear velocity Even in this case, it can be seen that the appearance is good.

In addition, when the weight average molecular weight of the insulating paint is less than 20000 as in Reference Examples a and b , the appearance is not very preferable, and when the weight average molecular weight of the insulating paint exceeds 30000 as in Reference Example c. Shows that workability is not good. From this, when the weight average molecular weight is between 20000 and 30000 as in Examples 1-1 to 1-8, it can be said that the appearance is the most preferable state and the workability is also preferable.

  Furthermore, in Table 2, the evaluation in the case of containing an alkoxylated melamine resin and / or a trialkylamine in addition to 1,3-dimethyl-2-imidazolidinone is performed. Furthermore, by containing an alkoxylated melamine resin and / or a trialkylamine, the adhesion is improved as compared with the case of Table 1 to which only 1,3-dimethyl-2-imidazolidinone is added. I understand. As in Example 2-11, it can be seen that when the content of the alkoxylated melamine resin is less than 5 parts by weight with respect to 100 parts by weight of the polyamideimide resin, the adhesion is low. Moreover, when it exceeds 20 weight part, it turns out that the raise softening temperature is low and the stability as a coating material is falling.

  Further, as in Examples 2-13 and 2-14, when the trialkylamine content is less than 0.05 parts by weight with respect to 100 parts by weight of the polyamideimide resin, the case of the alkoxylated melamine resin Similarly, when adhesiveness becomes low and exceeds 1.0 weight part, it turns out that the stability as a coating material falls and workability | operativity falls. When both the alkoxylated melamine resin and the trialkylamine are contained, when the amount is outside the above-described range as in Examples 2-15 and 2-16, the adhesiveness is reduced in the case of a small amount, and the case is large. It can be seen that the stability as a paint is reduced. As in Examples 2-1 to 2-3, 5 to 20 parts by weight of the alkoxylated melamine resin and / or 0.05 to 1.0 part by weight of the trialkylamine are based on 100 parts by weight of the polyamideimide resin. When it is contained, it can be seen that adhesion and stability as a coating are good.

Even when the alkoxylated melamine resin and / or trialkylamine is contained as in Reference Examples f and g , as in Reference Examples a and b , when the weight average molecular weight of the insulating coating is less than 20000, When the weight average molecular weight of the insulating coating exceeds 30000 as in Reference Example c , it is understood that the workability is not good.

The thermogravimetric analysis result regarding the insulating paint of this invention and the conventional insulating paint.

Claims (3)

An insulating paint in which a polyamide-imide resin is dissolved in an organic solvent,
The organic solvent comprises N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone ;
The content of the 1,3-dimethyl-2-imidazolidinone in the organic solvent is 10% by mass to 30% by mass,
A weight average molecular weight of the polyamideimide resin is 20000 or more and 30000 or less . For 100 parts by weight of the polyamideimide resin,
(I) 5-20 parts by weight of alkoxylated melamine resin,
(Ii) 0.05 to 1.0 part by weight of a trialkylamine, or
(Iii) 0.05 to 1.0 part by weight of a trialkylamine and 5 to 20 parts by weight of an alkoxylated melamine resin,
The insulating paint according to claim 1, further comprising: Claim 1 or 2 insulated wires insulating paint, characterized in that formed by coating baked or via another insulating layer on a conductor according to.

Images