JP2012172002A - Polyamideimide resin insulating paint and insulated electric wire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polyamideimide resin insulating paint capable of providing an insulation film which has the partial discharge inception voltage equal to or higher than that of the conventional insulation film at normal temperature and the partial discharge inception voltage of which is hardly lowered even in a high-humidity environment.SOLUTION: The polyamideimide resin insulating paint is obtained by mixing an isocyanate component (D) in a prepolymer, which is obtained by reacting an acid component, that comprises aromatic tricarboxylic anhydride (A) and aromatic tetracarboxylic dianhydride (B), with a diamine component (C). A mixing ratio of the aromatic tricarboxylic anhydride (A) with the aromatic tetracarboxylic dianhydride (B) is 50/50 to 10/90 ((A)/(B)) by the molar ratio.

Description

  The present invention relates to a polyamide-imide resin insulating paint and an insulated wire using the same, and more particularly to a polyamide-imide resin insulating paint suitable for a coil of an electric device such as a motor or a transformer and an insulated wire using the same.

  In general, coils of electrical equipment such as rotating electrical machines and transformers have polyimide or polyamideimide around a metal conductor (conductor) having a cross-sectional shape (for example, round shape or rectangular shape) that matches the purpose and shape of the coil. An insulated wire (enameled wire) provided with an insulating coating layer formed by forming one or more insulating films obtained by applying and baking an insulating paint in which a resin such as polyesterimide is dissolved in an organic solvent, Widely used.

  Electrical equipment such as rotating electrical machines and transformers are driven by inverter control, and in electrical equipment using such inverter control, high inverter surge voltage (surge voltage) is generated by inverter control. There is a risk of it. Thus, when an inverter surge voltage is generated in an electric device, a partial discharge may occur in the insulated wire constituting the coil of the electric device due to the inverter surge voltage, and the insulating film may be deteriorated or damaged.

  The deterioration of the insulating film due to the occurrence of partial discharge is attributed to minute voids existing in the insulating film. Insulating paint in which inorganic fine particles such as silica, alumina, titanium oxide or the like, or an organosol in which these inorganic fine particles are dispersed in a dispersion solvent, are dispersed in a resin paint as means for making the insulating film less susceptible to partial discharge. Insulated electric wires are known in which an insulating film is formed by coating and baking on a conductor (see, for example, Patent Documents 1 and 2).

  As another method for preventing the deterioration of the insulating film due to the inverter surge voltage, for example, two aromatic imide prepolymers containing an aromatic diamine component having three or more aromatic rings and an acid component are used. An insulated wire is known in which an insulating coating is formed by applying a polyamideimide resin insulating paint obtained by mixing an aromatic diisocyanate component having the following aromatic ring onto a conductor and baking it (see, for example, Patent Document 3). . In Patent Document 3, by using such a polyamide-imide resin insulating paint, an insulating film having a low relative dielectric constant can be obtained, and an insulated electric wire having a high partial discharge initiation voltage (PDIV) can be obtained. ing.

JP 2001-307557 A JP 2006-299204 A JP 2009-161683 A

  In recent years, hybrid vehicles and the like have begun to spread against the background of energy savings, etc., and electrical devices used for such applications are desired to be small and high-voltage driven in order to improve fuel efficiency and power performance of hybrid vehicles and the like. Therefore, inverter control is performed at a higher voltage than before. For this reason, recent insulated wires are required to have a higher partial discharge starting voltage than before in order to prevent partial discharge from occurring.

  Recently, there has been a demand for an insulated wire having an insulating film in which the partial discharge start voltage is almost stable regardless of changes in humidity.

  Accordingly, an object of the present invention is to provide a polyamide-imide resin insulating paint that has a partial discharge start voltage equal to or higher than that of the conventional one at room temperature, and can obtain an insulating film in which the partial discharge start voltage is less likely to decrease even in a high humidity environment, and insulation using the same. It is to provide electric wires.

  The present invention, which was created to solve the above problems, reacts an acid component comprising an aromatic tricarboxylic acid anhydride (A) and an aromatic tetracarboxylic dianhydride (B) with a diamine component (C). The prepolymer obtained by mixing the isocyanate component (D) with a molar ratio of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B). (A) / (B) = polyamideimide resin insulating paint with 50/50 to 10/90.

  The mixing ratio of the diamine component (C) and the acid component comprising the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) is (C) / (( A) + (B)) = 75/100 to 95/100.

  The aromatic tetracarboxylic dianhydride (B) may have a weight average molecular weight of 350 or less.

  The diamine component (C) may have a weight average molecular weight of 350 or more.

  In the presence of an azeotropic solvent, a prepolymer obtained by reacting the acid component composed of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) with the diamine component (C). Synthesize.

  Moreover, this invention is an insulated wire which has the insulating film formed by apply | coating and baking the said polyamidoimide resin insulating coating material on a conductor or another film | membrane.

  According to the present invention, there is provided a polyamide-imide resin insulating paint that has a partial discharge start voltage equal to or higher than that of a conventional one and is capable of obtaining an insulating film in which the partial discharge start voltage is hardly lowered even in a high humidity environment, and an insulated wire using the same. can do.

[Summary of embodiment]
In the present invention, since moisture is taken into the insulation film, the dielectric constant as the insulation film increases and the partial discharge start voltage decreases. We paid attention to the need for an insulating film with a small amount of insulation.

  And this invention, as a coating material which forms such an insulating film, the acid component which consists of aromatic tricarboxylic anhydride (A) and aromatic tetracarboxylic dianhydride (B), diamine component (C), The isocyanate component (D) is mixed with the prepolymer obtained by reacting, and the mixing ratio of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) is a molar ratio. (A) / (B) = 50/50 to 10/90, the polyamideimide resin insulation coating is employed, thereby reducing the amide group concentration per repeating unit of the polyamideimide resin and increasing the imide group concentration. be able to. In other words, in view of the fact that the imide group is less polar than the amide group, the hygroscopic rate is lowered by increasing the number of imide groups contained in the repeating unit of the polyamide-imide resin and decreasing the number of amide groups. The occurrence of partial discharge can be better suppressed regardless of humidity.

  As a result, it is possible to provide an insulated wire in which the partial discharge start voltage is unlikely to decrease even in a high humidity atmosphere.

  Hereinafter, a preferred embodiment of the polyamide-imide resin insulating paint in the present invention will be described in detail.

  In the present invention, an isocyanate component is added to a prepolymer obtained by reacting an acid component comprising an aromatic tricarboxylic acid anhydride (A) and an aromatic tetracarboxylic dianhydride (B) with a diamine component (C). (D) is mixed, and the blending ratio of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) is (A) / (B) = 50 / 50- It is a polyamide-imide resin insulating paint that is 10/90.

  Examples of the solvent used for the synthesis and coating of the present invention include N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, N, N-dimethylacetamide (DMAC), N, N-dimethylformamide (DMF), and dimethylimidazo. It may be synthesized in combination with a solvent that does not inhibit the synthesis reaction of polyamideimide resin such as lydinone (DMI), cyclohexanone, methylcyclohexanone, or may be diluted.

  Moreover, you may use together aromatic alkylbenzenes etc. for a dilution use. However, it is necessary to consider when there is a possibility of lowering the solubility of the polyamideimide resin.

  There is trimellitic anhydride (TMA) as the aromatic tricarboxylic acid anhydride (A) of the acid component. In addition, aromatic tricarboxylic acid anhydrides such as benzophenone tricarboxylic acid anhydride and hydrogenated compounds thereof can be used, but TMA is most preferable.

  As aromatic tetracarboxylic dianhydride (B), pyromellitic acid (PMDA), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 3,3 ′, 4,4 '-Diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-oxydiphthalic dianhydride (ODPA), 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 4,4 ' -(2,2-hexafluoroisopropylidene) diphthalic dianhydride (6FDA) and the like, and butanetetracarboxylic dianhydride and 5- (2,5-dioxotetrahydro-3- Furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, or alicyclic tetracarboxylic dianhydrides hydrogenated with the above exemplified tetracarboxylic dianhydrides, etc. It may be use. In order to efficiently obtain the effects of the present invention, 4,4′-oxydiphthalic dianhydride (ODPA), 3,3 ′, 4,4′-benzophenone is used as the aromatic tetracarboxylic dianhydride (B). A material having a weight average molecular weight (Mw) of 350 or less such as tetracarboxylic dianhydride (BTDA) may be used.

  As the diamine component (C), 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 4,4′-diaminodiphenylmethane (DAM), 4,4′-diaminodiphenyl ether (ODA), 3,3′-dimethyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4′-diaminobiphenyl (m-TB), 2,2′-bis (trifluoromethyl) -4,4 '-Diaminobiphenyl, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-bis (4-aminophenyl) sulfide, 4,4'-diaminodiphenyl sulfone, 4,4'-diamino Benzanilide, 9,9-bis (4-aminophenyl) fluorene (FDA), 1,4-bis (4-aminophenoxy) benzene (T EQ), 1,3-bis (4-aminophenoxy) benzene (TPE-R), 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis (4-aminophenoxyphenyl) propane (BAPP), bis [4- (4-aminophenoxy) phenyl] sulfone (BAPS), 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (HFBAPP) and the like are exemplified. In addition, hydrogenated compounds, halides, isomers, and the like of the diamine components exemplified above may be used or used in combination. Moreover, as a diamine component (C), it is good to use a thing with a weight average molecular weight (Mw) of 350 or more.

  In the method of reducing the dielectric constant, the presence of amide groups and imide groups contained in the polyamide-imide resin has the greatest effect on the increase of the dielectric constant. By reducing the concentration of these amide groups and imide groups contained in the repeating unit in the resin, the dielectric constant can be reduced, which is an effective means for improving the partial discharge starting voltage. For example, the effect of lowering the dielectric constant can be obtained by using a monomer having a large molecular weight.

  In particular, in the present invention, it is preferable to use a diamine component (C) having a weight average molecular weight (Mw) of 350 or more in order to efficiently obtain the effect of improving the partial discharge starting voltage.

  As the isocyanate component (D), in addition to the above 4,4′-diphenylmethane diisocyanate (MDI), general-purpose tolylene diisocyanate (TDI), naphthalene diisocyanate, xylylene diisocyanate, biphenyl diisocyanate, diphenyl sulfone diisocyanate And aromatic diisocyanates such as diphenyl ether diisocyanate, isomers, and multimers. If necessary, aliphatic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, or alicyclic diisocyanates and isomers obtained by hydrogenating the aromatic diisocyanates exemplified above may be used or used together.

  As the isocyanate component (D), 2,2-bis [4- (4-isocyanatophenoxy) phenyl] propane (BIPP), bis [4- (4-isocyanatophenoxy) phenyl] sulfone (BIPS), bis [4 -(4-isocyanatophenoxy) phenyl] ether (BIPE), full orange isocyanate (FDI), 4,4'-bis (4-isocyanatophenoxy) biphenyl, 1,4-bis (4-isocyanatophenoxy) benzene, etc. These isomers are also included. These production methods are not particularly limited, but a method using phosgene is industrially most suitable and desirable.

  When combined with an alicyclic raw material, the effect of reducing the dielectric constant and improving the transparency of the resin composition is expected, so it may be used together as necessary, but there is a possibility of causing a decrease in heat resistance. Care must be taken in the chemical structure.

  The mixing ratio of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) is preferably (A) / (B) = 50/50 to 10/90 in terms of molar ratio. “(A) / (B) = 50/50 to 10/90” indicates “50/50 or less, 10/90 or more”.

  When the mixing ratio of the aromatic tricarboxylic acid anhydride (A) to the aromatic tetracarboxylic dianhydride (B) is larger than 50/50 in terms of molar ratio, the number of carboxylic acids derived from the aromatic tricarboxylic acid anhydride (A) Increases, the amide group concentration per repeating unit increases, and the moisture absorption rate increases and the partial discharge start voltage decreases. Moreover, when the blending ratio of the aromatic tricarboxylic acid anhydride (A) to the aromatic tetracarboxylic dianhydride (B) is less than 10/90 in terms of molar ratio, the concentration of the ring-closing imide group per repeating unit is further increased. The solubility of the polyamide-imide resin is lowered, causing gelation. That is, an insulating paint suitable for forming an insulating film may not be obtained.

  Regarding the blending ratio of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B), (A) / (B) = 40.0 / 60.0 to 10/90 is more preferable. . “(A) / (B) = 40.0 / 60.0 to 10/90” indicates “40.0 / 60.0 or less, 10/90 or more”.

  The mixing ratio of the diamine component (C) and the acid component comprising the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) is (C) / ((A) + (B) ) = 75/100 to 95/100 (75/100 or more, 95/100 or less). In the range of the above blending ratio, the blending molar amount of the diamine component (C) is determined by the blending amount of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B), and the aromatic tricarboxylic acid. The total amount ((A) / 2 + (B)) of half the molar amount of the acid anhydride (A) and the molar amount of the aromatic tetracarboxylic dianhydride (B) is desirable. When deviating from this blending ratio range, the acid component or diamine component (C) of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) remains in the prepolymer, and the subsequent isocyanate There is a risk of hindering reaction with the component (D).

  The polyamideimide resin is synthesized from a prepolymer obtained by reacting an aromatic tricarboxylic acid anhydride (A), an aromatic tetracarboxylic dianhydride (B), and a diamine component (C). During the synthesis of the prepolymer, dehydration occurs due to imidization from an acid anhydride and an amine, and moisture increases in the system. This moisture reacts with the acid anhydride of aromatic tricarboxylic acid anhydride (A) or aromatic tetracarboxylic dianhydride (B) to form carboxylic acid, which greatly affects the polymerization. Therefore, it is desirable to synthesize the prepolymer in the presence of an azeotropic solvent (azeotropic solvent).

  The polyamide-imide resin having an increased imide group concentration has more water generated by imidization during synthesis and remains in the system and reacts with the acid anhydride. Therefore, the polymerization of the polyamide-imide resin is remarkably hindered, and there is a limit to increase the imide group concentration. However, in the present invention, by synthesizing a prepolymer in the presence of an azeotropic solvent, moisture generated by imidization can be removed out of the system, and a polyamide having a higher imide group concentration and a lower amide group concentration can be obtained. An imide resin can be obtained.

  As the azeotropic solvent, it is possible to use and use a solvent that can be azeotroped with water, such as toluene and xylene. It is desirable to synthesize a prepolymer while adding azeotropic dehydration in a synthesis system in which about 10% of the main solvent for synthesis is added and a reflux condenser, a moisture metering receiver, and the like are attached.

  Synthesis is performed by reacting the isocyanate component (D) with this prepolymer, and a solvent is further added and stirred to obtain a polyamideimide resin insulating paint.

  By applying and baking the thus obtained polyamideimide resin insulating paint on a conductor such as copper or another film, an insulating film can be formed to obtain an insulated wire. Various shapes such as a round wire and a flat wire can be used for the conductor, and an insulating film can be obtained by coating and baking on a film and a substrate.

  In addition, other films such as an adhesion layer for improving adhesion may be used above and below the insulating film, and a self-bonding layer may be provided on the insulating film.

  In short, according to the present invention, by increasing the number of imide groups contained in the repeating unit of the amide-imide resin and reducing the number of amide groups, an insulating film with a low moisture absorption rate can be formed, and in a high-humidity atmosphere. As a result, an insulated wire in which the partial discharge start voltage is hardly lowered can be obtained.

  Examples 1 to 6 and Comparative Examples 1 to 4 will be described.

(Synthesis method of polyamideimide resin insulating paint according to Examples 1 to 6)
Prepare a flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, moisture meter, and diamine component (C) and acid component aromatic tricarboxylic acid anhydride as the first stage synthesis reaction Product (A), aromatic tetracarboxylic dianhydride (B), 50-80% of the main solvent, and 10% of the main solvent azeotropic solvent are added up to 180 ° C. with stirring in a nitrogen atmosphere. The mixture was heated and reacted at this temperature for 4 hours while removing water produced by the dehydration reaction. After cooling to 60 ° C. while maintaining the nitrogen atmosphere, the diisocyanate component (D) was added, and as a second stage synthesis reaction, the mixture was heated to 140 ° C. with stirring in a nitrogen atmosphere and reacted for about 1 hour. After confirming that the viscosity was sufficiently increased, benzyl alcohol having a molar ratio of about 2% of the acid component and the remainder of the main solvent were added and the reaction was stopped by stirring at 140 ° C. for 30 minutes. Thereby, a polyamide-imide resin insulating paint is obtained.

(Synthesis Method of Polyamideimide Resin Insulating Paint According to Comparative Example 1)
Prepare a flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, moisture meter, and add diisocyanate component (D), acid component aromatic tricarboxylic acid anhydride (A), and solvent. The mixture was heated to 140 ° C. with stirring in a nitrogen atmosphere and reacted for about 1 hour. After confirming that the viscosity was sufficiently increased, benzyl alcohol having a molar ratio of about 2% of the acid component and the remainder of the solvent were added, and the reaction was stopped by stirring at 140 ° C. for 30 minutes. Thereby, a polyamide-imide resin insulating paint is obtained.

(Synthesis method of polyamideimide resin insulating paint according to Comparative Examples 2 to 4)
Prepare a flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, moisture meter, and diamine component (C) and acid component aromatic tricarboxylic acid anhydride as the first stage synthesis reaction The product (A), the aromatic tetracarboxylic dianhydride (B), and 50 to 80% of the main solvent are added, heated to 180 ° C. with stirring in a nitrogen atmosphere, and the water produced by the dehydration reaction is removed. The reaction was carried out at this temperature for 4 hours while leaving the system. After cooling to 60 ° C. while maintaining the nitrogen atmosphere, the diisocyanate component (D) was added, and as a second stage synthesis reaction, the mixture was heated to 140 ° C. with stirring in a nitrogen atmosphere and allowed to react for about 1 hour. After confirming that the viscosity was sufficiently increased, benzyl alcohol having a molar ratio of about 2% of the acid component and the remainder of the solvent were added, and the reaction was stopped by stirring at 140 ° C. for 30 minutes. Thereby, a polyamide-imide resin insulating paint is obtained.

  Further, this polyamideimide resin insulating coating was applied onto a conductor having a diameter of 0.8 mm and baked to obtain an enameled wire having an insulating film with a film thickness of 40 μm.

  Tables 1 and 2 show the components used in Examples 1 to 6 and Comparative Examples 1 to 4, their blend ratios, the properties of the enamel wires obtained, and the like.

(Partial discharge start voltage measurement)
The enameled wire was cut into 500 mm, a twisted pair enameled wire sample was prepared, and the insulating film was cut to a position 10 mm from the end portion to form a terminal processing portion. Measurement is performed using a partial discharge automatic test system (DAC-PD-3, manufactured by Soken Denki Co., Ltd.) with an electrode connected to the terminal processing unit, and a voltage of 50 Hz is applied in an atmosphere at a temperature of 25 ° C. and a humidity of 50%. While increasing the voltage at a rate of 10 to 30 V / s, the voltage was measured when 100 pC discharge was generated at 50 times / second on the enameled wire of the twisted pair. This was repeated three times, and the average value of the measured voltage values was defined as the partial discharge start voltage.

(Measurement of moisture absorption rate)
A coiled sample was prepared by winding a 30 mm turn of an enamel wire on a round bar having a diameter of 25 mm, and the sample was cured in a constant temperature bath at 100 ° C. for 15 minutes. Next, after the initial weight of the sample immediately after taking out from the thermostat was measured, it was stored in a thermostatic oven of 40 ° C. × 95% RH. After 24 hours, the weight after taking out the sample in the constant temperature and humidity chamber was measured. After that, the sample was immersed in sodium hydroxide at 400 ° C for 4 minutes to remove the insulating film, rinsed with water, then the weight of the remaining conductor was measured, and the moisture absorption rate was calculated from the weight difference of the sample insulating film. did.

Example 1
As the synthesis of the first stage, 307.7 g (0.75 mol) of BAPP as diamine component (C), 96.1 g (0.5 mol) of TMA as tricarboxylic acid anhydride (A) and tetracarboxylic dianhydride (B ) ODPA 156.0 g (0.5 mol), 1051 g of NMP as a solvent and 105.1 g of xylene as an azeotropic solvent were added, and synthesis was performed while taking water out of the system at 180 ° C. After cooling to 60 ° C. while maintaining, as the second stage synthesis, 62.6 g (0.25 mol) of MDI was added as the diisocyanate component (D) and synthesis was carried out at 140 ° C. After 1 hour, about 2% benzyl alcohol and 451 g of NMP were added and stirred for 30 minutes to obtain a polyamide-imide resin insulating paint.

(Example 2)
As the synthesis in the first stage, 348.7 g (0.85 mol) of BAPP as the diamine component (C), 57.6 g (0.3 mol) of TMA as the tricarboxylic acid anhydride (A), and tetracarboxylic dianhydride (B ) ODPA 218.4 g (0.7 mol), 1133 g NMP as a solvent and 113.3 g xylene as an azeotropic solvent, and synthesizing while leaving water out at 180 ° C. After cooling to 60 ° C. while maintaining, 37.5 g (0.15 mol) of MDI was added as a diisocyanate component (D) as the second stage synthesis, and synthesis was carried out at 140 ° C. After 1 hour, about 2% benzyl alcohol and 451 g of NMP were added and stirred for 30 minutes to obtain a polyamide-imide resin insulating paint.

(Example 3)
As the synthesis of the first stage, 389.7 g (0.95 mol) of BAPP as the diamine component (C), 19.2 g (0.1 mol) of TMA as the tricarboxylic acid anhydride (A) and tetracarboxylic dianhydride (B ) 280.8 g (0.9 mol) of ODPA and 1214 g of NMP as a solvent and 121.4 g of xylene as an azeotropic solvent, and synthesizing while taking water out of the system at 180 ° C. After cooling to 60 ° C. while maintaining, as the second stage synthesis, 12.5 g (0.05 mol) of MDI was added as the diisocyanate component (D), and synthesis was carried out at 140 ° C. After 1 hour, about 2% benzyl alcohol and 520 g of NMP were added and stirred for 30 minutes to obtain a polyamide-imide resin insulating paint.

Example 4
As the synthesis in the first stage, 150.0 g (0.75 mol) of ODA as the diamine component (C), 96.1 g (0.5 mol) of TMA as the tricarboxylic acid anhydride (A), and tetracarboxylic dianhydride (B ) BTDA 161.1 g (0.5 mol), 761 g of NMP as a solvent and 76.1 g of xylene as an azeotropic solvent were added, and synthesis was carried out while taking water out of the system at 180 ° C. After cooling to 60 ° C. while maintaining, as the second stage synthesis, 62.6 g (0.25 mol) of MDI was added as the diisocyanate component (D) and synthesis was carried out at 140 ° C. One hour later, about 2% benzyl alcohol and 326 g of NMP were added and stirred for 30 minutes to obtain a polyamide-imide resin insulating paint.

(Example 5)
As the synthesis of the first stage, 170.0 g (0.85 mol) of ODA as the diamine component (C), 57.6 g (0.3 mol) of TMA as the tricarboxylic acid anhydride (A) and tetracarboxylic dianhydride (B ) BTDA 225.5 g (0.7 mol), 824 g of NMP as a solvent and 82.4 g of xylene as an azeotropic solvent, and synthesizing while taking water out of the system at 180 ° C. After cooling to 60 ° C. while maintaining, 37.5 g (0.15 mol) of MDI was added as a diisocyanate component (D) as the second stage synthesis, and synthesis was carried out at 140 ° C. After 1 hour, about 2% benzyl alcohol and 353 g of NMP were added and stirred for 30 minutes to obtain a polyamide-imide resin insulating paint.

(Example 6)
As the synthesis of the first stage, 190.0 g (0.95 mol) of ODA as the diamine component (C), 19.2 g (0.1 mol) of TMA as the tricarboxylic acid anhydride (A) and tetracarboxylic dianhydride (B ) 290.0 g (0.9 mol) of BTDA and 871 g of NMP as a solvent and 87.1 g of xylene as an azeotropic solvent were added, and synthesis was performed while taking water out of the system at 180 ° C. After cooling to 60 ° C. while maintaining, as the second stage synthesis, 12.5 g (0.05 mol) of MDI was added as the diisocyanate component (D), and synthesis was carried out at 140 ° C. After 1 hour, about 2% benzyl alcohol of acid component and 373 g of NMP were added and stirred for 30 minutes to obtain a polyamideimide resin insulating coating.

(Comparative Example 1)
TMA 192.1 g (1.0 mol) as the tricarboxylic acid anhydride (A), MDI 250.0 g (1.0 mol) as the diisocyanate component (D) and 1300 g NMP as the solvent were added and synthesized at 140 ° C. It was. After 1 hour, about 2% benzyl alcohol of acid component and 373 g of NMP were added and stirred for 30 minutes to obtain a polyamideimide resin insulating coating.

(Comparative Example 2)
As the synthesis of the first stage, 215.4 g (0.53 mol) of BAPP as the diamine component (C), 182.5 g (0.95 mol) of TMA as the tricarboxylic acid anhydride (A) and tetracarboxylic dianhydride (B ) 15.6 g (0.05 mol) of ODPA and 853 g of NMP as a solvent, and synthesis was carried out while discharging water outside the system at 180 ° C., and after cooling to 60 ° C. while maintaining a nitrogen atmosphere, As the second stage synthesis, 118.9 g (0.48 mol) of MDI was added as the diisocyanate component (D), and synthesis was performed at 140 ° C. After 1 hour, about 2% benzyl alcohol and 366 g of NMP were added and stirred for 30 minutes to obtain a polyamide-imide resin insulating paint.

(Comparative Example 3)
As the synthesis of the first stage, 291.1 g (0.71 mol) of BAPP as the diamine component (C), 111.4 g (0.58 mol) of TMA as the tricarboxylic acid anhydride (A) and tetracarboxylic dianhydride (B ) DSDA 150.4 g (0.42 mol) and 1200 g NMP as a solvent were added, and synthesis was performed while discharging water outside the system at 180 ° C., and after cooling to 60 ° C. while maintaining a nitrogen atmosphere, As the second-stage synthesis, 72.5 g (0.29 mol) of MDI was added as the diisocyanate component (D) and synthesized at 140 ° C. After 1 hour, about 2% benzyl alcohol of acid component and 600 g of NMP were added and stirred for 30 minutes to obtain a polyamideimide resin insulating coating.

(Comparative Example 4)
As the synthesis of the first stage, 409.2 g (0.9975 mol) of BAPP as the diamine component (C), 1.0 g (0.005 mol) of TMA as the tricarboxylic acid anhydride (A), and tetracarboxylic dianhydride (B ) ODPA 310.4 g (0.995 mol) and 1237 g NMP as a solvent were added, and synthesis was performed while discharging water outside the system at 180 ° C., and after cooling to 60 ° C. while maintaining a nitrogen atmosphere, The paint was not obtained.

  Comparative Example 1 shows a polyamide-imide enameled wire that is used for general purposes, but has good flexibility and adhesion, but has a high relative dielectric constant and a low partial discharge starting voltage. The moisture absorption after 24 hours at 40 ° C. and 95% RH is as high as 4.8%.

  On the other hand, the partial discharge starting voltage is greatly improved in the polyamideimide enamel wires of Examples 1 to 6. Moreover, in Examples 1-3, the moisture absorption rate after 24 hours in 40 degreeC and 95% RH is especially low.

  Comparative Example 3 is an example having a blending molar ratio 58/42 of the tricarboxylic acid anhydride (A) and the tetracarboxylic acid dianhydride (B). The relative dielectric constant is high and the partial discharge start voltage is low. Moreover, the moisture absorption after 24 hours in 40 degreeC and 95% RH is as high as 3.5%.

  Comparative Example 4 is an example having a mixing molar ratio of 0.5 / 99.5 of tricarboxylic acid anhydride (A) and tetracarboxylic acid dianhydride (B) using the same raw materials as in Examples 1 to 3. After the completion of the first stage synthesis, a solid was deposited upon cooling, and a polyamideimide paint could not be obtained. This is because the imide group concentration per repeating unit is large and the solubility is significantly reduced.

Claims (6)

  An isocyanate component (D) is added to a prepolymer obtained by reacting an acid component composed of an aromatic tricarboxylic acid anhydride (A) and an aromatic tetracarboxylic dianhydride (B) with a diamine component (C). The mixture ratio of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) is a molar ratio of (A) / (B) = 50/50 to 10 / 90. Polyamideimide resin insulating paint, characterized by being 90.   The mixing ratio of the diamine component (C) and the acid component comprising the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) is (C) / (( The polyamideimide resin insulating paint according to claim 1, wherein A) + (B)) = 75/100 to 95/100.   The polyamide-imide resin insulating paint according to claim 1 or 2, wherein the aromatic tetracarboxylic dianhydride (B) has a weight average molecular weight of 350 or less.   The polyamide-imide resin insulating paint according to any one of claims 1 to 3, wherein the diamine component (C) has a weight average molecular weight of 350 or more.   In the presence of an azeotropic solvent, a prepolymer obtained by reacting the acid component composed of the aromatic tricarboxylic acid anhydride (A) and the aromatic tetracarboxylic dianhydride (B) with the diamine component (C). The polyamide-imide resin insulating paint according to any one of claims 1 to 4, which is synthesized.   An insulated wire comprising an insulating film formed by applying and baking the polyamideimide resin insulating paint according to any one of claims 1 to 4 on a conductor or another film.