JP2015127424A - Polyamideimide resin, insulating coating material, insulating coating and insulating wire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide primarily a polyamideimide resin excellent in heat resistance and further improved in breakdown voltage so as to contribute to high-voltage driving; and to provide secondly a polyamideimide resin contributing further to downsizing, weight saving and the like.SOLUTION: This polyamideimide resin is obtained by reacting: a polycarboxylic acid compound essentially including trivalent or higher polycarboxylic acid anhydride having an acid anhydride and a carboxyl group; 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane represented by the general formula (1); and another aromatic polyamino compound or an aromatic polyisocyanate compound in a basic polar solvent.

Description

  The present invention relates to a polyamide-imide resin having excellent breakdown voltage characteristics, an electrical insulating material including the same, an insulating paint, and an insulating enameled wire using the same.

In recent years, inverter-controlled electrical equipment has been frequently used for energy saving and variable speed control.
In particular, high efficiency is advancing in hybrid vehicles and industrial motors, and inverters are driven as variable speed devices in control systems, and miniaturization, weight reduction, high heat resistance, and high voltage drive are rapidly progressing. In recent years, elements capable of high-speed switching such as IGBTs (Insulated Gate Bipolar Transistors) have been developed as power devices for inverters, and as a result, surge voltage rises, and cases of early dielectric breakdown increase.
As one of the causes, when a high voltage is applied to the motor coil, partial discharge is likely to occur in the insulating film of the insulated wire. It was determined that the occurrence of the partial discharge was caused by the local deterioration of insulation, which eventually caused dielectric breakdown and shortened the life of the insulated enamel wire and the motor.

  On the other hand, polyamideimide resins are used in various applications as important insulating materials because they are excellent in heat resistance, chemical resistance and hydrolysis resistance. In particular, motors for automobiles (including motors for hybrid cars) are often installed in the presence of transmission oil, and as a required characteristic for windings used for motors, they are not affected by mission oil, It is necessary to suppress hydrolysis due to moisture, and it is also necessary to withstand use at high temperatures. From such a viewpoint, the polyamide-imide resin is indispensable as an insulating paint.

  As a method of prolonging the life of the insulated enameled wire and the motor, a method of making the partial discharge less likely is considered, but as a method of suppressing the partial discharge in the insulating film of the insulated wire using this polyamideimide resin, A method is known in which the dielectric constant of the polyamide-imide resin is lowered, thereby increasing the partial discharge start voltage. As a method for reducing the dielectric constant of a polyamide-imide resin, a method of introducing a specific molecular structure into the polyamide-imide resin is known (see Patent Document 1 and Patent Document 2). Further, as a method for reducing the dielectric constant of a polyamideimide resin, it has been proposed to blend a fluororesin or a polysulfone resin, which is a low dielectric constant resin, with the polyamideimide resin (see Patent Document 3).

JP 2009-161683 A JP 2009-292904 A JP 2010-67521 A

Even if we try to suppress the partial discharge by trying to reduce the electric field by reducing the dielectric constant of the insulating resin, it is difficult to eliminate the partial discharge completely. It is important to increase the dielectric breakdown voltage of the insulating coating.
That is, as a method of extending the life of the insulated wire and the motor, a method of increasing the dielectric breakdown voltage of the insulating film of the insulated wire can be considered.
And suppression of the partial discharge by the low dielectric constant of insulating resin does not necessarily lead to the improvement of a dielectric breakdown voltage.
The present invention solves such a problem. First, it provides a polyamide-imide resin with improved breakdown voltage and excellent heat resistance so as to contribute to higher voltage drive. Second, it further provides a polyamide-imide resin that can contribute to reduction in size and weight, and further provides an insulating coating and an enameled wire using the same.

で表される２，２−ビス［４−（４−アミノフェノキシ）フェニル］ヘキサフルオロプロパン〔（Ｂ）成分〕、あるいは上記（Ａ）成分、上記（Ｂ）成分及び芳香族ポリイソシアネート化合物若しくは（Ｂ）成分以外の芳香族ポリアミノ化合物〔（Ｃ）成分〕を塩基性極性溶媒中で反応させて得られることを特徴とするポリアミドイミド樹脂。
２． （Ｂ）成分と（Ｃ）成分との配合割合｛（Ｃ）成分／（Ｂ）成分｝が、当量比で０．９９／０．０１〜０／１である項１記載のポリアミドイミド樹脂。
３． （Ｂ）成分と（Ｃ）成分の合計に対する（Ａ）成分の配合割合｛（Ａ）成分／〔（Ｂ）成分＋（Ｃ）成分〕｝が当量比で０．６〜１．４である項１または２記載のポリアミドイミド樹脂。
４． ポリアミドイミド樹脂が、数平均分子量９，０００〜９０，０００のものである項１〜３いずれかに記載のポリアミドイミド樹脂。
５． 項１〜４記載のポリアミドイミド樹脂を塗膜成分としてなる絶縁塗料。
６． 項５記載の塗料を用いて導体上に塗布し、焼付けてなる絶縁電線。 The present invention relates to the following.
1. A polycarboxylic acid compound [component (A)] comprising a polycarboxylic acid anhydride having a trivalent or higher valence having an acid anhydride group and a carboxyl group and the general formula (1)

2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane [component (B)], or the component (A), the component (B) and the aromatic polyisocyanate compound or ( B) Polyamideimide resin obtained by reacting an aromatic polyamino compound other than component (component (C)) in a basic polar solvent.
2. Item 2. The polyamideimide resin according to Item 1, wherein the blending ratio {(C) component / (B) component} of the component (B) and the component (C) is 0.99 / 0.01 to 0/1 in terms of equivalent ratio.
3. The blending ratio {(A) component / [(B) component + (C) component]} of the component (A) with respect to the sum of the component (B) and the component (C) is 0.6 to 1.4 in an equivalent ratio. Item 3. The polyamideimide resin according to item 1 or 2.
4). Item 4. The polyamideimide resin according to any one of Items 1 to 3, wherein the polyamideimide resin has a number average molecular weight of 9,000 to 90,000.
5. Item 5. An insulating coating comprising the polyamideimide resin according to Items 1 to 4 as a coating film component.
6). An insulated wire which is applied on a conductor using the paint according to Item 5 and baked.

  The polyamideimide resin of the present invention and the coating film using the same have improved breakdown voltage. Therefore, the insulated wire obtained by using the paint is useful for application to a high voltage drive motor, an inverter control electric device, and the like. In the present invention, excellent dielectric breakdown voltage characteristics are exhibited even if the thickness of the coating is reduced.

  The polyamide-imide resin according to the present invention has a fluorine atom in the molecular structure, and is a tricarboxylic acid anhydride compound (sometimes referred to as “acid component”), 2,2-bis [4- (4-aminophenoxy). ) Phenyl] hexafluoropropane and optionally aromatic diisocyanate compound or aromatic diamino compound other than the above compound.

  Examples of the tricarboxylic acid anhydride compound include trivalent carboxylic acid anhydrides having an acid anhydride group represented by the following general formula (I) or (II), but an acid anhydride that reacts with an isocyanate group or an amino group. The trivalent carboxylic acid having a group is not particularly limited, including its derivatives. In view of heat resistance, those having an aromatic group are preferred, and trimellitic anhydride is particularly preferred in view of heat resistance and cost. These may be used alone or in combination depending on the purpose.

（Ｙは−ＣＨ_２−、−ＣＯ−、−ＳＯ_２−又は−Ｏ−を示す。）

(Y represents —CH ₂ —, —CO—, —SO ₂ — or —O—)

  In addition, if necessary, a part of the acid component may be tetracarboxylic dianhydride (pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′. , 4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, 1,4 5,8-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, m-terphenyl-3,3 ' , 4,4'-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis (2,3-or 3,4-dicarboxyphenyl) propane dianhydride, 2,2-bi (2,3- or 3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1 , 1,1,3,3,3-hexafluoro-2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1,3-bis (3 , 4-Dicarboxyphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride, butanetetracarboxylic dianhydride, bicyclo- [2,2,2] -oct-7-ene-2: And tetracarboxylic dianhydrides such as 3: 5: 6-tetracarboxylic dianhydride).

2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane is used as the reaction partner of the above tricarboxylic acid anhydride compound.
You may use together an aromatic diisocyanate compound or aromatic diamino compounds other than the said compound.
As an aromatic diisocyanate compound or an aromatic diamino compound other than the above compounds, an aromatic compound having a divalent amino group or an isocyanate group represented by the following general formulas (III), (IV), and (V) can be used.

［これらの式中、Ｒ^２はアルキル基、水酸基又はアルコキシ基であり、Ｒ^３はアミノ基またはイソシアネート基である。Ｒ^２のアルキル基又はアルコキシ基としては炭素数１〜２０のものが好ましい。］

[In these formulas, R ² is an alkyl group, a hydroxyl group or an alkoxy group, and R ³ is an amino group or an isocyanate group. The alkyl group or alkoxy group of R ² preferably has 1 to 20 carbon atoms. ]

  Examples of the aromatic diisocyanate compound or aromatic diamino compound represented by the general formula (III), (IV) or (V) include 4,4′-diisocyanatodiphenylmethane, 4,4′-diisocyanatobiphenyl, 3 , 3'-diisocyanatobiphenyl, 3,4'-diisocyanatobiphenyl, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 4,4'-diisocyanato-2,2'-dimethylbiphenyl, 4, , 4'-diisocyanato-3,3'-diethylbiphenyl, 4,4'-diisocyanato-2,2'-diethylbiphenyl, 4,4'-diisocyanato-3,3'-dimethoxybiphenyl, 4,4'-diisocyanato -2,2'-dimethoxybiphenyl, 1,5-diisocyanatonaphthalene, 2,6-diisocyanatonaphthalene, 4, '-Diaminodiphenylmethane, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 3,4'-diaminobiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino -2,2'-dimethylbiphenyl, 4,4'-diamino-3,3'-diethylbiphenyl, 4,4'-diamino-2,2'-diethylbiphenyl, 4,4'-diamino-3,3 ' -Dimethoxybiphenyl, 4,4'-diamino-2,2'-dimethoxybiphenyl, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, etc., which can be used alone or in combination it can.

  Examples of the aromatic diisocyanate compound or aromatic diamino compound include other aromatic diisocyanate compounds or aromatic diamino compounds such as tolylene diisocyanate, xylylene diisocyanate, 4,4′-diisocyanatodiphenyl ether, 2,2- Bis [4- (4′-isocyanatophenoxy) phenyl] propane, tolylenediamine, xylylenediamine, 4,4′-diaminodiphenyl ether, and the like can be used.

  Examples of the diisocyanate compound or diamino compound include hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, diaminoisophorone, bis (4-aminocyclohexyl) methane, 1,4-diaminotranscyclohexane, hydrogenated m-xylylene. Range amine, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, diisocyanatoisophorone, bis (4-isocyanatocyclohexyl) methane, 1,4-diisocyanatotranscyclohexane, hydrogenated m-xylylene diisocyanate Aliphatic or alicyclic isocyanate compounds such as can be used, but when these are used, the above-mentioned aromatic diisocyanate compound or aromatic diamino compound can be used in combination. Masui. The amount of these used is preferably 50 mol% or less of the total amount of the diisocyanate compound or diamino compound from the viewpoint of the heat resistance of the resulting resin. A tri- or higher functional polyisocyanate compound can also be used in combination.

  As an aromatic diisocyanate compound or an aromatic diamino compound used in combination with 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, the balance of heat resistance, solubility, mechanical properties, cost, etc. is considered. In this case, 4,4′-diphenylmethane diisocyanate or 4,4′-diaminodiphenylmethane is particularly preferable.

  In addition, as the diisocyanate compound, a compound in which an isocyanate group is stabilized with a blocking agent may be used if necessary in order to avoid changes over time. The blocking agent includes alcohol, phenol, oxime, etc., but there is no particular limitation.

  In the present invention, the use ratio of the (C) component to the (B) component [(C) component / (B) component] is used so that the equivalent ratio is 0.99 / 0.1 to 0/1. Furthermore, 0.8 / 0.2 to 0.3 / 0.7 is preferable, and it is particularly preferable to use 0.7 / 0.3 to 0.5 / 0.5. preferable. If the proportion of component (B) used is too small, the effect of the present invention will be reduced.

  The component (A), the component (B), and the component (C) are the component (B) with respect to the total number (a) of the carboxyl group and acid anhydride group of the component (A) and the reactive hydroxyl group, if present. C) It is preferable that the ratio [(a) / (b)] to the total number (b) of the amino group of the component and optionally the diisocyanate compound isocyanate group is 0.6 to 1.4, 0.7 -1.3 is more preferable, and 0.8-1.2 is particularly preferable. If this ratio is too small, it tends to be difficult to increase the molecular weight of the resin. If this ratio is too large, the foaming reaction becomes intense, the amount of unreacted substances remaining increases, and the stability of the resin. Tend to get worse.

The polyamideimide resin according to the present invention can be obtained, for example, by the following production method.
(1) A method of synthesizing a polyamide-imide resin by using (A) component, (B) component and, if necessary, (C) component at a time and reacting them.
(2) The component (B) and, if necessary, the component (C) are reacted in excess with respect to the component (A) to synthesize an amideimide oligomer having an amino group or an isocyanate group at the terminal, and then the component (A) A method of adding and reacting to synthesize a polyamideimide resin.
(3) After synthesizing an excess of the component (A), the component (B) and the component (C) as necessary to synthesize an amide imide oligomer or imide dicarboxylic acid compound having an acid or acid anhydride group at the terminal , (A) component, (B) component and, if necessary, (C) component is added and reacted to synthesize a polyamideimide resin.
In particular, in order to obtain desired properties, an excess amount of component (A) and component (B) are reacted to synthesize an imide dicarboxylic acid compound having a carboxyl group at both ends, and then component (A), component (B) The method of adding and reacting the component (C) and the component (C) as required is particularly preferred. In this case, when synthesizing an imide dicarboxylic acid compound, the component (A) / component (B) (equal ratio) is used so that it becomes 2/1 or almost 2/1. ) Component and (C) component as needed, [(A) component + imidodicarboxylic acid compound] / [(B) component + (C) component] is 0.9 / It is particularly preferable to add 1 to 1.4 / 1.

  The amount of the synthetic solvent used during the reaction is preferably 100 to 300 parts by weight with respect to 100 parts by weight of the total amount of component (B) and optionally (C) component relative to component (A), More preferably, it is 150 to 250 parts by weight. If the amount of the synthetic solvent used is too small, the foaming reaction tends to occur. If the amount is too large, the synthesis time tends to be long, and the resin concentration is low. It tends to be difficult to form a film. Synthetic solvents include N-methyl-2-pyrrolidone, N, N′-dimethylformamide, γ-butyrolactone, N, N′-dimethylpropyleneurea [1,3-dimethyl-3,4,5,6-tetrahydropyrim. Dimin-2 (1H) -one], polar solvents such as dimethyl sulfoxide, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, sulfolane, aromatic hydrocarbon solvents such as xylene and toluene, and ketones such as methyl ethyl ketone and methyl isobutyl ketone are used. Is done.

The polyamideimide resin thus obtained preferably has a number average molecular weight of 9,000 to 90,000. If the number average molecular weight is too small, the film-forming property when used as a paint tends to be poor, and if the number average molecular weight is too large, the viscosity increases when dissolved in a solvent at an appropriate concentration as a paint, and during coating There is a tendency that workability of is inferior. For this reason, the number average molecular weight of the polyamideimide resin is more preferably 10,000 to 70,000.
The adjustment of the number average molecular weight within the above range can be performed by managing so as to continue the synthesis for a required time.

  In this specification, the number average molecular weight of the resin is a value measured by gel permeation chromatography (GPC) and converted using a standard polystyrene calibration curve.

  The polyamide-imide resin of the present invention is further added with an additive such as a colorant, if necessary, and dissolved or diluted with the same solvent as the above-described synthetic solvent as necessary to obtain an appropriate viscosity. It can be adjusted to be a material for electrical insulation or an insulating paint. In the case of an insulating paint, the solid content is generally 10 to 50% by weight. A synthetic solution of polyamideimide resin may be used for the production of such an electrical insulating material or insulating coating.

The material for electrical insulation or the insulating paint of the present invention can be dried and cured by heat treatment at 260 to 520 ° C. for several seconds to several tens of minutes after being applied to the object. When cured at a low temperature, the solvent remains, and the coating properties that protect the substrate may be inferior. Moreover, in the case of curing at less than 260 ° C., the coating film is not sufficiently cured and may be dissolved or swollen in a polar solvent. If the heating time is too short, the residual solvent may remain on the coating film and the properties of the coating film applied to the substrate may be inferior. If the heating time is too long, not only will it be wasted, but if necessary, May cause undesirable side reactions with the added additives.
The electrical insulating material or insulating paint containing the polyamideimide resin according to the present invention can also be used as an insulating material for coil impregnation.

  Examples of the object to be coated include a metal wire such as a copper wire and other materials to which insulation is imparted. When a metal wire is used, an enameled wire with high insulation reliability excellent in chemical resistance, hydrolysis resistance, heat resistance, dielectric breakdown voltage characteristics and the like can be obtained. The cross-sectional shape of the metal wire may be circular, square, rectangular, or flat.

  As a method of applying the electrical insulating material or insulating paint according to the present invention, there are die coating, felt coating, etc. when applying to an electric wire (metal wire), and brush coating, dip coating (dipping) for other applications. ) Etc. In order to harden the coil itself, a method of dripping and impregnating the coil and a method of dipping the coil (dipping) can be mentioned.

Using an insulating material or an insulating coating material containing a polyamide-imide resin according to the present invention, an insulating layer is formed on the conductor, thereby providing excellent dielectric breakdown resistance (dielectric breakdown voltage)), and Can be improved. This is particularly effective for insulating insulated wires. In addition, in a stator or rotor having a coil using this insulated wire, and further in an inverter drive motor and other high voltage drive motors and inverter control electric devices using these stators or rotors, their dielectric breakdown resistance (insulation) (Breakdown voltage) is improved. In addition, the insulating layer formed from the polyamide-imide resin according to the present invention using an electrical insulating material or an insulating paint is excellent in the above characteristics even if it is a thin film, contributing to miniaturization and weight reduction of these devices. You can also
Examples of the inverter drive motor include a motor for a hybrid vehicle, a motor for an electric vehicle, a motor for a hybrid diesel locomotive, a motor for an electric motorcycle, a motor for an elevator, and a motor used for a construction machine.
The electrical insulating material or insulating paint containing the polyamide-imide resin according to the present invention can be used for insulating plates, insulating coating plates and the like that require high voltage resistance.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

155.6 g (0.3 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (hereinafter referred to as “HFBAPP”) as component (B) and trimellitic anhydride as component (A) In a nitrogen stream in which 115.3 g (0.6 mol) of acid and 406.4 g of N-methyl-2-pyrrolidone as a reaction solvent were charged into a flask equipped with a thermometer, a stirrer and a condenser, the mixture was dried. The temperature was gradually raised over about 1 hour, the temperature was raised to 170 ° C., and the temperature was kept at 170 ° C. for 4 hours to obtain an imide dicarboxylic compound (0.3 mol).
Furthermore, in this reaction liquid, 134.5 g (0.7 mol) of trimellitic anhydride as component (A) and 254.0 g (1.015 mol) of diphenylmethane-4,4′-diisocyanate as component (C) and the reaction solvent Was charged with 582.7 g of N-methyl-2-pyrrolidone and gradually raised to 140 ° C. over about 4 hours, paying attention to the sudden foaming of carbon dioxide generated by the reaction, and then reacted for 6 hours. Thus, a solution of polyamideimide resin having a number average molecular weight of 23100 was obtained.
The blending ratio of the component (A), the component (B) and the component (C) used in this reaction is as follows in terms of equivalent ratio.
{(B) component / (C) component} = 0.30 / 1.015 (= 0.23 / 0.77)
{(A) component / [(B) component + (C) component]} = 1.3 / 1.315 (= 0.99 / 1)
The obtained solution was diluted with N-methyl-2-pyrrolidone to obtain an insulating coating having a resin concentration of 31.8% by weight.

(B) 259.3 g (0.5 mol) of HFBAPP as component, 192.1 g (1.0 mol) of trimellitic anhydride as component (A) and 677.1 g of N-methyl-2-pyrrolidone as a reaction solvent at temperature The flask was equipped with a meter, a stirrer, and a cooling tube, and the mixture was gradually heated up to 170 ° C. over about 1 hour in a dried nitrogen stream, and kept at 170 ° C. for 5 hours. , Imidodicarboxylic acid (0.5 mol) was obtained.
Further, 96.1 g (0.5 mol) of trimellitic anhydride as component (A) and 254.0 g (1.015 mol) of diphenylmethane-4,4′-diisocyanate as component (C) and reaction solvent were added to this reaction solution. N-methyl-2-pyrrolidone (525.2 g) was added, and the temperature was raised gradually to 140 ° C. over about 4 hours, paying attention to the sudden foaming of carbon dioxide generated by the reaction, and then reacted for 6 hours. Thus, a solution of a polyamideimide resin having a number average molecular weight of 24,700 was obtained.
The blending ratios of component (A), component (B), and component (C) used in this reaction are as follows in terms of equivalent ratio.
{(B) component / (C) component} = 0.50 / 1.015 (= 0.33 / 0.67)
{(A) component / [(B) component + (C) component]} = 1.5 / 1.515 (= 0.99 / 1)
The obtained solution was diluted with N-methyl-2-pyrrolidone to obtain an insulating coating having a resin concentration of 31.4% by weight.

As component (B), 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (HFBAPP) 362.9 g (0.7 mol) and as component (A) 269.0 g of trimellitic anhydride (1.4 mol) and 947.9 g of N-methyl-2-pyrrolidone as a reaction solvent were charged into a flask equipped with a thermometer, a stirrer and a condenser, and the mixture was dried in a nitrogen stream for about 1 hour. The temperature was gradually raised to 170 ° C. and kept at 170 ° C. for 5 hours to obtain imidodicarboxylic acid (0.7 mol).
Further, 57.6 g (0.3 mol) of trimellitic anhydride as component (A) and 254.0 g (1.015 mol) of diphenylmethane-4,4′-diisocyanate as component (C) and reaction solvent were added to this reaction solution. N-methyl-2-pyrrolidone (467.4 g) was added, and the temperature was raised gradually to 140 ° C. over about 4 hours, paying attention to the sudden foaming of carbon dioxide gas generated by the reaction, and then reacted for 5 hours. Thus, a solution of a resin composition for electrical insulation of polyamideimide having a number average molecular weight of 27,300 was obtained.
The blending ratios of component (A), component (B), and component (C) used in this reaction are as follows in terms of equivalent ratio.
{(B) component / (C) component} = 0.70 / 1.015 (= 0.41 / 0.59)
{(A) component / [(B) component + (C) component]} = 1.7 / 1.715 (= 0.99 / 1)
The obtained solution was diluted with N-methyl-2-pyrrolidone to obtain an insulating coating having a resin concentration of 30.9% by weight.

Comparative Example 1
192.1 g (1.0 mol) of trimellitic anhydride, 262.8 g (1.05 mol) of 4,4′-diphenylmethane diisocyanate, and 682.4 g of N-methyl-2-pyrrolidone were thermometer, stirrer and condenser. The mixture was placed in a flask equipped with this, and the mixture was gradually heated to 140 ° C. over about 3 hours in a dry nitrogen stream while paying attention to the sudden bubbling of carbon dioxide generated by the reaction. Was kept at 140 ° C. for 5 hours to obtain a polyamideimide resin solution having a number average molecular weight of 22400. This solution was diluted with N-methyl-2-pyrrolidone to obtain an insulating coating having a resin concentration of 31.9%.

Comparative Example 2
192.1 g (1.0 mol) of trimellitic anhydride, 262.8 g (1.05 mol) of 4,4′-diphenylmethane diisocyanate, and 682.4 g of N-methyl-2-pyrrolidone were thermometer, stirrer and condenser. The mixture was placed in a flask equipped with this, and the mixture was gradually heated to 140 ° C. over about 3 hours in a dry nitrogen stream while paying attention to the sudden bubbling of carbon dioxide generated by the reaction. Was kept at 140 ° C. for 7 hours to obtain a polyamideimide resin solution having a number average molecular weight of 27,500. This solution was diluted with N-methyl-2-pyrrolidone to obtain an insulating coating having a resin concentration of 31.1%.

Test Examples The insulating paints obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were applied to a copper wire having a diameter of 1.0 mm according to the following baking conditions, and baked at a wire speed of 16 m / min to produce an insulated wire. .
[Coating / baking conditions]
Baking furnace: Hot air type furnace (furnace length 5.5m)
Furnace temperature: Inlet / Outlet = 320 ° C / 430 ° C
Coating method: The procedure of passing through the baking furnace by squeezing the insulated wire through which the resin composition is passed with a die is performed 8 times. The diameters of the dies from the first to the eighth time were changed to 1.05 mm, 1.06 mm, 1.07 mm, 1.08 mm, 1.09 mm, 1.10 mm, 1.11 mm, and 1.12 mm.
Moreover, the characteristics (flexibility, unidirectional wear, dielectric breakdown voltage, softening resistance) of the obtained insulated wires were measured according to JIS C3003. 1 ml of enamel wire is immersed in glycerin pressure resistance: glycerin / saturated saline weight ratio = 85/15, and JIS C 3003.10. The same voltage as (1) was increased at a specified speed, and the breakdown voltage was measured (detection current 5 mA). The results are shown in Table 1.

  From the results shown in Table 1, the insulated wires produced using the insulating paints obtained in Examples 1 to 3 are superior in resistance to dielectric breakdown and softening resistant as compared with those obtained in Comparative Examples. It can also be seen that the unidirectional wear is almost equally good.

Claims (9)

A polycarboxylic acid compound (component (A)) essentially comprising a tricarboxylic or higher polycarboxylic acid anhydride having an acid anhydride group and a carboxyl group;
General formula (1)

2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane [(B) component], and aromatic polyisocyanate compound or aromatic polyamino compound other than component (B) [(C )component〕
Polyamideimide resin obtained by reacting in a basic polar solvent.   The polyamideimide resin according to claim 1, wherein the component (C) is an aromatic polyisocyanate compound. The polyamideimide resin according to claim 1, wherein the component (C) is an aromatic compound having a divalent amino group or an isocyanate group represented by the following general formulas (III), (IV), and (V).

[In these formulas, R ² is an alkyl group, a hydroxyl group or an alkoxy group, and R ³ is an amino group or an isocyanate group. ]   The blending ratio {(C) component / (B) component} of the component (B) and the component (C) is 0.99 / 0.01 to 0/1 in an equivalent ratio. The polyamide-imide resin described.   The blending ratio {(A) component / [(B) component + (C) component]} of the component (A) with respect to the sum of the component (B) and the component (C) is 0.6 to 1.4 in an equivalent ratio. The polyamideimide resin according to claim 1.   The polyamideimide resin according to any one of claims 1 to 5, wherein the polyamideimide resin has a number average molecular weight of 9,000 to 90,000.   The material for electrical insulation containing the polyamide-imide resin of Claims 1-6.   An insulating paint comprising the polyamideimide resin according to claim 1 as a coating film component.   An insulated wire formed by applying and baking on a conductor using the paint according to claim 8.