JP4934624B2 - Insulated wire - Google Patents

Description

  The present invention relates to an insulating paint that provides an insulating coating excellent in workability, which is optimal for constituting a coil of a motor or a generator, and an insulated wire coated and baked with this paint.

  In recent years, there has been an increasing need for miniaturization, weight reduction, and high output of motors and generators, and in order to achieve this, it has become necessary to wrap more insulated wires around the motor core. . For this reason, more insulated wires are packed in a narrow core slot, and the coating of insulated wires is required to withstand severe processing conditions and to maintain insulation performance. ing.

  Insulated wires using a general polyamideimide resin, for example, insulated wires using a polyamideimide resin synthesized by polymerization from diphenylmethane-4,4′-diisocyanate (MDI) and trimellitic anhydride (TMA), If it uses for said use, it will be damaged by the severe force received at the time of a process, and the problem of producing a malfunction in an electrical property has arisen.

  Conventionally, 4,4'-bitolylene diisocyanate (TODI) is added to the raw material for varnish to introduce a biphenyl structure into the molecular structure of polyamideimide (Patent Document 1), and further improve the damage resistance of insulated wires. Therefore, in addition to the strength of the insulating film, the flexibility of the conductor is specified (Patent Document 3), or pyromellitic dianhydride (TMA) in addition to trimellitic anhydride (TMA) as an acid anhydride used in the synthesis ( (PMDA) has been proposed (Patent Document 2) to improve the processing resistance by increasing the elastic modulus of the insulating coating by increasing the proportion of imide groups in the molecular structure.

Japanese Patent No. 2936895 Japanese Patent No. 3777305 WO99 / 41757 republished patent gazette

  In the above known example, although the elastic modulus can be improved by increasing the proportion of 4,4′-bitolylene diisocyanate (TODI) used as a raw material and increasing the proportion of the biphenyl structure in the polyamideimide, There arises a problem that flexibility is deteriorated. It has also been proposed to use diphenylmethane-4,4'-diisocyanate (MDI) to compensate for flexibility, but when used in combination with MDI, it becomes too soft and the design molecular weight is set to a high molecular weight in order to obtain a high elastic modulus. Need to be on the side. Therefore, in order to satisfy the processing resistance, it is necessary to increase the molecular weight of the polyamideimide, and the viscosity of the varnish becomes large. When coating the wire, the viscosity is adjusted by diluting with a solvent. It will be necessary. Therefore, in order to obtain a predetermined insulating film thickness, the number of times of coating has to be increased, resulting in a problem that workability and productivity are deteriorated.

  In addition, 4,4′-bitolylene diisocyanate (TODI) is a material that is much more expensive than diphenylmethane-4,4′-diisocyanate (MDI) and tolylene diisocyanate (TDI). If used, the varnish price and the price of insulated wires using the varnish will rise.

  On the other hand, even when pyromellitic dianhydride (PMDA) is used in combination with trimellitic anhydride (TMA) as an acid anhydride for varnish synthesis, the proportion of PMDA used as a raw material is increased in polyamideimide Although an improvement in the elastic modulus can be expected by increasing the proportion of the imide structure, there has been a problem that the solubility in a solvent is remarkably lowered and the workability at the time of coating and baking onto a conductor is hindered.

  Accordingly, an object of the present invention is an insulating film having excellent film properties with excellent workability, flexibility and elastic modulus, and having good solubility, workability / productivity, and economical efficiency. The object is to provide an insulating paint to be provided, an insulated wire coated and baked with the paint, and a motor using the same.

  By using tolylene diisocyanate (TDI) having a bent structure as the diisocyanate component used in the synthesis of polyamideimide in the present invention, the solubility in a solvent is improved even if the proportion of biphenyl structure and imide group in the polyamideimide molecule is increased. Therefore, the workability at the time of application / baking is good, and the insulated wire after application / baking can maintain the mechanical strength of the coating that can avoid damage even in a severe winding process. Unlike the case where diphenylmethane-4,4′-diisocyanate (MDI) is used as a bending structure imparting component by using TDI as a bending structure imparting component, there is no part that freely rotates, so that it is more rigid than using MDI. This is probably because TDI has a higher elastic modulus than MDI, even if the molecular weight of the resulting polyamideimide is somewhat smaller.

  Diphenylmethane-4,4′-diisocyanate (MDI) can also be used as a component for imparting a bent structure in the polyamideimide molecular chain during varnish synthesis, but the obtained varnish is coated and baked to form a polyamideimide coating. In order to develop wear resistance equivalent to that of a polyamide-imide film created by applying and baking a varnish synthesized using tolylene diisocyanate (TDI), the molecular weight of the polyamide-imide in the varnish should be less than when TDI is used. Since it is necessary to adjust to a high molecular weight, the varnish viscosity increases, and the workability at the time of coating and baking onto a conductor is hindered. Therefore, it is desirable to use TDI rather than MDI as the diisocyanate component that imparts a bent structure. As another means for introducing the bent structure into the polyamideimide molecular chain, isophthalic acid can also be used as an acid component used in the synthesis of polyamideimide.

  Based on the above knowledge, the present inventors select TDI as a diisocyanate component that imparts a bent structure, and in a polyamideimide synthesized using equimolar amounts of a diisocyanate component and an acid component, Participating 4,4'-bitolylene diisocyanate (TODI) and tolylene diisocyanate (TDI) and pyromellitic dianhydride (PMDA) and trimellitic anhydride (TMA) involved as acid components Focusing on the composition, as a result of intensive studies, 4,4'-bitolylene diisocyanate (TODI) 5 to 33 mol% and tolylene diisocyanate (TDI) 95 to 67 mol% in all diisocyanate components, in all acid components , Pyromellitic dianhydride (PMDA) 5-60 mol%, and trimelli By polymerization reaction using a preparative acid anhydride (TMA) 95 to 40 mol%, it found that the object of the present invention are solved, leading to completion of the present invention.

The object of the present invention has been achieved by the following means.
1. In the polyamideimide synthesized using equimolar amounts of diisocyanate component and acid component, in all diisocyanate components, formula (1)

5 to 33 mol% of 4,4'-bitolylene diisocyanate represented by the formula (2)

95-67 mol% of tolylene diisocyanate represented by the formula (3)

5 to 60 mol% of pyromellitic dianhydride represented by the formula (4)

An insulating paint comprising an insulating resin varnish obtained by polymerizing trimellitic anhydride represented by the formula (95) to 40 mol%.

2. The 4,4'-vitrylene diisocyanate represented by the formula (1) is represented by the formula (1a)

4. The insulating paint according to 1 or 3, which is 3,3′-dimethylbiphenyl-4,4′-diisocyanate represented by
3. 3. The insulating paint according to any one of 1 and 2, wherein the tolylene diisocyanate represented by the formula (2) is a mixture of its 2,4-isomer and 2,6-isomer.
4). The insulated wire which the insulating layer which apply | coated and baked the insulating paint in any one of said 1-3 is all or one part of an insulating film.
5. 5. The insulated wire according to 4 above, which has a surface lubricating layer.
6). A motor using the insulated wire according to 4 or 5 above.

  The present invention provides an insulating paint that provides an insulating coating excellent in workability, which is optimal for constituting coils of motors and generators, and an insulated wire coated and baked with this paint. According to the present invention, it can withstand severe processing conditions, is not damaged at the time of processing, can maintain insulation performance, does not cause defects in electrical characteristics, is resistant to trauma, processing resistance, wear resistance, flexibility Insulating coating that provides an insulating coating with excellent elastic modulus and good film properties, good solubility, workability and productivity, and good economic efficiency, and an insulated wire coated and baked with this coating And a motor using the same can be provided.

Insulating paint according to the present invention is a polyamideimide synthesized using equimolar amounts of a diisocyanate component and an acid component.
Of all diisocyanate components, formula (1)

5 to 33 mol% of 4,4'-vitrylene diisocyanate (abbreviated as TODI) represented by formula (2)

95 to 67 mol% of tolylene diisocyanate (abbreviated as TDI) represented by the formula (3)

5 to 60 mol% of pyromellitic dianhydride (abbreviated as PMDA) represented by formula (4)

Is an insulating paint made of an insulating resin varnish obtained by polymerizing 95 to 40 mol% of trimellitic anhydride (abbreviated as TMA).

  Specific examples of 4,4'-vitrylene diisocyanate (TODI) represented by the formula (1) include those represented by the formula (1a)

2,3′-dimethylbiphenyl-4,4′-diisocyanate, 2,2′-dimethylbiphenyl-4,4′-diisocyanate and 2,3′-dimethylbiphenyl-4,4′-diisocyanate Among these, 3,3′-dimethylbiphenyl-4,4′-diisocyanate is preferable.

  Specific examples of tolylene diisocyanate (TDI) represented by the formula (2) include those represented by the formula (2a)

2,4-tolylene diisocyanate represented by the formula (2b)

2,6-tolylene diisocyanate, a mixture of these isomers, 2,3-tolylene diisocyanate, 2,5-tolylene diisocyanate, 3,4-tolylene diisocyanate, 3,5-tolylene diisocyanate Isocyanates and mixtures of these two or more isomers. Among these, specific examples of the mixture of the 2,4-isomer and the 2,6-isomer of tolylene diisocyanate will give a mass ratio of 2,4-isomer and 2,6-isomer of 80. : 20, or 65:35 isomer mixtures.

  The polyamide-imide resin insulating paint (resin composition) used for forming the insulating layer in the present invention is synthesized by an ordinary method, for example, using a diisocyanate component and an acid component in equimolar amounts in a polar solvent. In the diisocyanate component, 4,4′-bitolylene diisocyanate (TODI) 5 to 33 mol%, and tolylene diisocyanate (TDI) 95 to 67 mol%, in all acid components, pyromellitic dianhydride (PMDA) 5 The polymerization reaction can be carried out using ˜60 mol% and trimellitic anhydride (TMA) 95-40 mol%.

The acid component of the present invention is composed of pyromellitic acid dihydrate (PMDA) and trimellitic anhydride (TMA) and does not contain benzophenone tetracarboxylic dianhydride (abbreviated as BTDA).
Benzophenone tetracarboxylic dianhydride (BTDA) has an absorption region at 250 to 380 nm due to its benzophenone skeleton, and acts as a hydrogen abstraction type radical polymerization initiator. Therefore, it is considered that problems occur in varnish stability and stability over time of the film. In addition, the heat resistance of the polymer is superior in the case of using pyromellitic acid dihydrate (PMDA) than in the case of using benzophenone tetracarboxylic dianhydride (BDTA). Benzophenone tetracarboxylic dianhydride (BDTA) is not included in the acid component of the present invention.

  The solvent used in the synthesis may be any solvent as long as the resin prepared can be dissolved, and N, N′-dimethylformamide, N, N′-dimethylacetamide, N-methyl-2-pyrrolidone, etc. may be used. it can. Of these, N-methyl-2-pyrrolidone is preferred.

  The polyamideimide resin paint thus obtained is applied and baked directly on the conductor or through another layer to form an insulating layer on the conductor. The other layer here refers to an insulating resin layer made of a resin that can be generally used as a coating resin for an enamel-coated electric wire such as a heat-resistant polyester resin, a polyesterimide resin, a polyamide-imide resin, or a polyimide resin, and is a process required for the coated electric wire. The resin to be used can be selected according to conditions and heat resistance.

  In addition, various additives (for example, lubricants, inorganic fine powders, metal alkoxylates, and the like) that are conventionally known to be added to an insulating film are added to each insulating layer within a range that does not impair the object of the present invention. Can be added.

  For example, by providing a surface lubricating layer on the outermost layer of the multilayer coated electric wire, the work resistance of the electric wire can be further improved. The surface lubrication layer mentioned here refers to a resin coating layer formed by applying and baking a varnish in which lubricant fine particles are dispersed in a polyamideimide resin solution. Lubricants dispersed in the resin solution can be selected from ester waxes such as carnauba wax and montan wax, and synthetic resin waxes such as polyethylene and polytetrafluoroethylene (PTFE) according to the lubrication performance to be applied to the wire surface. 1 type or multiple types can be used.

  In the present invention, a method for applying these resin varnishes on the conductor may be a conventional method, for example, a method using a varnish application die having a similar shape to the conductor shape, or if the conductor cross-sectional shape is a square, A die called a “universal die” formed in a cross beam shape can be used. The conductor coated with these resin varnishes is baked in a baking furnace by a conventional method. The specific baking conditions depend on the shape of the furnace used, but in the case of a natural convection type vertical furnace of about 5 m, the passage time is set to 400 to 500 ° C. to 30 to 90 seconds. Can be achieved.

  In the insulated wire of the present invention, the conductor is usually made of copper or an alloy thereof. Further, the total film thickness of the insulating coating is not particularly limited. The total film thickness is preferably 3 to 5% of the conductor diameter (diameter). For example, in the case of a conductor having a diameter of 1.0 mm, the total thickness of the insulating coating is preferably 30 to 50 μm.

  As an embodiment of the rotating electric machine using the above-described insulated wire, it is applied to the armature 2 of the motor 1 as shown in FIG. 1, and in particular, the insulated wire 5 is inserted into the slot 4 of the laminated core 3 shown as a partial view in FIG. The example which wound is shown. Of course, the motor is not limited to this structure. A plus-less motor that constitutes an armature in which a magnet roller is arranged in the center and an insulated wire is wound around a slot of a laminated core around the magnet roller. It can be applied to all types of rotating electrical machines such as machines.

  Hereinafter, the present invention will be further described with reference to examples. However, the present invention is not limited by these examples.

[Synthesis method of varnish]
A synthesis device equipped with a heating / cooling device, a nitrogen introducing device, and a stirrer was prepared in a three-liter flask having a volume of 3 liters. Among them, TMA 96.1 g (0.5 mol), PMDA 109.1 g (0.5 mol), TDI 139.3 g (0.8 mol), TODI 52.9 g (0.2 mol), and N- Methyl-2-pyrrolidone (NMP) 1096.6g was added, and it heated up from normal temperature to 140 degreeC over 2 hours, stirring in nitrogen stream. Stirring was continued at 140 ° C. for 2 hours until the generation of carbon dioxide gas was observed from inside the flask and the solution in the flask became viscous. Thereafter, the mixture was cooled to room temperature to obtain 1406 g of a polyamideimide varnish composition 1 (resin concentration: 22% by mass).

By the method similar to the said synthesis method, each component of the quantity shown in Table 1 was added, and the polyamideimide varnish compositions 2-13 were obtained. In compositions 9 and 13, varnish was turbid. Varnishes prepared with the respective compositions were applied to a glass plate to a thickness of about 30 μm, heated at 150 ° C. for 10 minutes, and then baked at 250 ° C. for 10 minutes to prepare a polyamideimide film. In the varnishes of compositions 9, 11, and 13, fine cracks occurred after baking, and a film could not be prepared. Table 1 shows the varnish properties of compositions 1 to 13, the varnish viscosity, and the elastic modulus of the films prepared with compositions 1 to 8, 10, and 12. The varnish properties, the varnish viscosity measurement method, the coating properties, the elastic modulus test method and the evaluation criteria are as follows.
(A) Varnish properties Visual confirmation after synthesis. A solution that became a uniform viscous solution was defined as “good”, and a solution that did not become a uniform solution and became cloudy was defined as “turbidity”.
(B) Varnish viscosity measuring method It measured at 30 +/- 0.5 degreeC using the B-type viscosity meter based on the varnish for enameled wire of JISC2351.
(C) Covering property test method (evaluation method) A coating film that was peeled off from a heated glass plate was evaluated as “good”, and a film that cracked during heating or wearing and could not be peeled into a film It was evaluated as “cracked” and recorded in Table 1.
(D) Elastic modulus test method (evaluation method) The S-S curve obtained by cutting the film after heating and baking into a width of 10 mm and a length of 100 mm and measuring the distance between marked lines with a tensile tester at 50 mm and a tensile speed of 5 mm / min. More elastic modulus was obtained.

In Table 1, TMA, PMDA, TDI, and TODI indicate the following.
TMA: trimellitic anhydride PMDA: pyromellitic dianhydride TDI: tolylene diisocyanate (mass ratio of 2,4-isomer and 2,6-isomer is
80:20 isomer mixture)
TODI: 3,3′-dimethylbiphenyl-4,4′-diisocyanate

[Electric wire manufacturing]
Table 2 summarizes the results of coating and baking onto a conductor (1.2 mm diameter) using each composition in Table 1.
Compositions 1 to 7 are shown as Examples 1 to 7, respectively. Compositions 8 to 13 are shown as Comparative Examples 1 to 6, respectively.
Since varnishes of compositions 9, 11, and 13 had difficulty in producing wires in a state where the solid content was 22% by mass, they were diluted with NMP to a solid content of 13, 15, and 13% by mass, respectively, and used for wire production.
Each wire was subjected to a unidirectional wear test (JIS-C3003) as a workability evaluation and a self-diameter winding test as a flexibility evaluation. The test method and evaluation criteria of the self-diameter winding test are as follows.

(E) Self-diameter winding test method In accordance with the flexibility test method of JIS-C3003, when the wire is wound tightly 10 times so that the wire comes into contact with the periphery of the coated wire itself, a crack is visible in which the conductor is visible on the coating. The occurrence of the occurrence was examined using a magnifier of about 15 times.
Evaluation criteria ○: No cracks in magnifying glass observations Kiretsu: Cracks in which conductors can be seen by magnifying glass observations

  According to the results of Tables 1 and 2, in Comparative Examples 1, 3, and 5, the value of the unidirectional wear characteristic is inferior to that of Examples 1-7. Further, in Comparative Examples 2, 4, and 6, cracks are observed by self-diameter winding, and it is understood that the flexibility is inferior. On the other hand, TODI20,33,30 mol% and TDI80,67,70 mol% in all diisocyanate components, PMDA50,50,25 mol%, and TMA50,50,75 mol% in all acid components are used. In the compositions 1, 2, and 4 subjected to the polymerization reaction, the film properties are good, the elastic modulus and the flexibility (self-diameter winding) are not only good, but the film is particularly difficult to peel (unidirectional wear characteristics). It turns out that it is excellent. Moreover, using TODI as the total diisocyanate component without using TODI, in the total acid component, PMDA 20, 33 mol% and TMA 80, 67 mol% were used for the polymerization reaction 3, 5 and in the total diisocyanate component, In Compositions 6 and 7 polymerized using TODI 60 mol% and TDI 40 mol%, PMDA 20,33 mol%, and TMA 80,67 mol% in the total acid components, the film properties are good and elastic. It can be seen that not only the rate and flexibility (self-diameter winding) are good, but also the film is harder to peel (unidirectional wear characteristics) or is superior in flexibility than Comparative Examples 1-6.

It is a schematic cross section of a motor.

Explanation of symbols

1 Motor 2 Armature 3 Laminated Core 4 Slot 5 Insulated Wire

Claims (6)

In the polyamideimide synthesized using equimolar amounts of diisocyanate component and acid component, in all diisocyanate components, formula (1)

5 to 33 mol% of 4,4′-vitrylene diisocyanate represented by the formula (2)

95-67 mol% of tolylene diisocyanate represented by the formula (3)

5 to 60 mol% of pyromellitic dianhydride represented by the formula (4)

An insulating paint comprising an insulating resin varnish obtained by polymerizing trimellitic anhydride represented by the formula (95) to 40 mol%. The 4,4′-vitrylene diisocyanate represented by the formula (1) is represented by the formula (1a)

The insulating paint according to claim 1, which is 3,3′-dimethylbiphenyl-4,4′-diisocyanate represented by the formula:   The insulating paint according to claim 1 or 2, wherein the tolylene diisocyanate represented by the formula (2) is a mixture of the 2,4-isomer and the 2,6-isomer.   The insulated wire in which the insulating layer which apply | coated and baked the insulating coating material of any one of Claims 1-3 is all or one part of an insulating film.   The insulated wire according to claim 4 having a surface lubricating layer.   A motor using the insulated wire according to claim 4.

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