JP2010031101A - Polyamideimide resin coating and insulated electric wire using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamideimide resin coating satisfying both requirements to a coating in viewpoint of production and to a produced insulation coating for heat resistance; a method for producing it; and an insulated electrical wire using the coating. <P>SOLUTION: The polyamideimide resin coating is produced by reacting a diisocyanate component with a carboxylic acid component containing trimellitic anhydride and 1,2,5-trimellitic acid, wherein the 1,2,5-trimellitic acid comprises 0.03-0.13 equivalent in the acidic component, the equivalence ratio of the diisocyanate component to the carboxylic acid component (diisocyanate/acid) is more than 1 to 1.3, and the content of the 1,2,5-trimellitic acid in the acid component is 0.04 to 0.13 equivalent, preferably 1.03-1.3. It is preferred that the excess isocyanate group is blocked with alcohol. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyamide-imide resin paint suitable for insulation coating such as a magnet wire, a method for producing the same, and an insulated wire coated with insulation using the paint.

Polyamideimide coatings are excellent in heat resistance and wear resistance, and are therefore used as insulating coatings for magnet wires that require mechanical strength and heat resistance.
The polyamide-imide coating is usually synthesized by mixing diisocyanate and trimellitic anhydride so as to be 1 equivalent each and reacting them.

  On the other hand, with the recent reduction in size and weight of motors, the amount of insulated wires wound around the motor core is increasing. For this reason, the insulated wire in the slot of the core is in a state where it tends to generate heat, such as being in contact with a high load applied, and the demand for improved heat resistance is increasing.

  However, as described above, the softening temperature of the insulated wire that is insulation-coated using the polyamide-imide paint synthesized by mixing and reacting the diisocyanate and trimellitic anhydride to 1 equivalent each is as follows: Since the temperature is about 400 ° C., further improvements in heat resistance are required from recent specifications of magnet wires.

Under such circumstances, various proposals have been made for improving the properties of polyamide-imide paints used for insulating films.
For example, in Japanese Patent Application Laid-Open No. 7-21849, by introducing a polyfunctional group into the structure of polyamideimide to improve the crosslink density, heat softening resistance is improved. A component containing at least one of a polyisocyanate compound having three or more isocyanate groups and a polycarboxylic acid compound having three or more carboxylic acid groups, and a polyisocyanate compound based on the total amount of the isocyanate component and the acid component; A polyamide-imide paint having a constant total content of polycarboxylic acid compounds has been proposed. Specifically, two types of acid components, trimellitic anhydride (TMA) and trimellitic acid (ETM), are proposed. , Diphenylmethane-4,4′-diisocyanate (MDI) was added at a ratio of 1: 1 (molar ratio). In the method for preparing the midimide-based paint, the content ratio of ETM with respect to the total amount of the acid component and the isocyanate component was 1.7 mol% (Example 1), 3.45 mol% (Example 2), 6.45 mol%. Example 3 discloses a polyamideimide coating material of 8.7 mol% (Comparative Example 2). And, in the polyamideimide-based paint having such a configuration, the higher the ETM content ratio, the higher the softening point and the heat resistant softening property of the insulating coating is improved, but when the ETM content ratio exceeds 8 mol%, Since the flexibility of the insulating coating is remarkably deteriorated, the content ratio of ETM is set to 8 mol% or less, and further considering the flexibility of the insulating coating, it is 3 mol% or less. (Corresponding to 06 equivalents) (paragraph number 0057).

JP 7-21849 A

  However, depending on the type and ratio of the polycarboxylic acid, there are problems that it takes a long time for the synthesis reaction or gelation due to the reaction being too fast, making it impossible to produce the paint itself. The fact is that no satisfactory polyamide-imide resin coating has been found.

  The present invention has been made in view of such circumstances, and the object thereof is a polyamide-imide resin paint that can satisfy both the manufacturing viewpoint of the paint and the heat resistance requirement of the formed insulating coating, It is another object of the present invention to provide an insulated wire using the paint.

  That is, the polyamide-imide resin paint of the present invention is a polyamide-imide resin paint obtained by reacting a diisocyanate component with a carboxylic acid component containing trimellitic anhydride and 1,2,5-trimellitic acid. 2,5-trimellitic acid is contained in the acid component in an amount of 0.03 equivalent to 0.13 equivalent, and the equivalent ratio of the diisocyanate component to the carboxylic acid component (diisocyanate / acid) is more than 1 to 1.3. Preferably, the content of the 1,2,5-trimellitic acid in the acid component is 0.04 equivalent to 0.13 equivalent, and the equivalent ratio of the diisocyanate component to the carboxylic acid component (diisocyanate / acid) is 1.03-1.3. Moreover, it is preferable that the excess isocyanate group is blocked with alcohol.

  The method for producing a polyamide-imide resin paint of the present invention comprises an acid component containing 0.97 to 0.87 equivalent of trimellitic anhydride and 0.03 equivalent to 0.13 equivalent of 1,2,5-trimellitic acid, and a diisocyanate component Are mixed so that the equivalent ratio of the carboxylic acid component to the diisocyanate component (diisocyanate / acid) is more than 1 to 1.3, and the viscosity of the solution when diluted to a non-volatile content of 27% by mass is 2500 cps. Until it becomes above, after making it react at about 120-150 degreeC, it dilutes by addition of an organic solvent, and it falls. It is preferable to add more alcohol after the temperature has dropped.

  The insulated wire of the present invention is an insulated wire comprising a conductor and an insulating film covering the conductor, and the insulating film is formed by baking after applying the polyamideimide resin paint of the present invention. It has a layer.

  In addition, the equivalent of 1,2,5-trimellitic acid referred to in the present specification is an equivalent calculated by using 1,2,5-trimellitic acid as bifunctional.

  The polyamide-imide paint of the present invention is manufactured under an excess of isocyanate component, so that even if the content of polycarboxylic acid is high, it is possible to avoid an increase in manufacturing time and manufacturing cost, and to be heat resistant. An excellent coating can be provided.

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

  The polyamide-imide resin paint of the present invention is a polyamide-imide resin paint obtained by reacting a diisocyanate component with a carboxylic acid component containing trimellitic anhydride and 1,2,5-trimellitic acid. The content ratio of 5-trimellitic acid and the equivalent ratio of the acid component and the isocyanate component are within a specific range.

  As the diisocyanate component used in the present invention, aromatic diisocyanate is preferably used. For example, as this aromatic diisocyanate, diphenylmethane-4,4′-diisocyanate (MDI), diphenylmethane-3,3′-diisocyanate, diphenylmethane-3,4′-diisocyanate, diphenylether-4,4′-diisocyanate, benzophenone— 4,4′-diisocyanate, diphenylsulfone-4,4′-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, naphthylene-1,5-diisocyanate, m-xylylene diisocyanate, p-xylylene Examples include range isocyanate. These can be used alone or in admixture of two or more. Of these, inexpensive MDI is preferably used.

  Examples of the diisocyanate component include biphenyl-4,4′-diisocyanate, biphenyl-3,3′-diisocyanate, biphenyl-3,4′-diisocyanate, 3,3′-dichlorobiphenyl-4,4 ′ in addition to the above diisocyanate. -Diisocyanate, 2,2'-dichlorobiphenyl-4,4'-diisocyanate, 3,3'-dibromobiphenyl-4,4'-diisocyanate, 2,2'-dibromobiphenyl-4,4'-diisocyanate, 3, 3′-dimethylbiphenyl-4,4′-diisocyanate, 2,2′-dimethylbiphenyl-4,4′-diisocyanate, 2,3′-dimethylbiphenyl-4,4′-diisocyanate, 3,3′-diethylbiphenyl -4,4'-diisocyanate, 2,2'-diethylbiphenyl-4,4'-diisocyanate 3,3′-dimethoxybiphenyl-4,4′-diisocyanate, 2,2′-dimethoxybiphenyl-4,4′-diisocyanate, 2,3′-dimethoxybiphenyl-4,4′-diisocyanate, 3,3 '-Diethoxybiphenyl-4,4'-diisocyanate, 2,2'-diethoxybiphenyl-4,4'-diisocyanate, 2,3'-diethoxybiphenyl-4,4'-diisocyanate and the like can also be used. .

  Acid components used for the synthesis of polyamideimide include trimellitic anhydride (TMA) and 1,2,5-trimellitic acid (1,2,5-ETM). Furthermore, biphenyltetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, diphenylsulfone tetracarboxylic dianhydride, oxydiphthalic dianhydride (OPDA), pyromellitic dianhydride (PMDA), 4,4 ′ -Aromatic tetracarboxylic dianhydrides such as (2,2-hexafluoroisopropylidene) diphthalic dianhydride (6FDA) and ethylene glycol bis (anhydrotrimellitate); However, it is preferable that the polycarboxylic acid containing three or more free carboxyl groups is only 1,2,5-ETM. This is because a polycarboxylic acid such as 1,3,5-ETM has a high reactivity with diisocyanate, and the reaction proceeds so quickly that it tends to be difficult to synthesize the paint. In this regard, as in 1,2,5-ETM, during a polymerization reaction with a diisocyanate, if a carboxyl group is bonded at a position that causes steric hindrance, the reaction is slow or under certain conditions, Since a part cannot participate in the reaction, a polyamideimide having a free carboxyl group, that is, a polyamideimide resin suitable as a coating material can be obtained.

  Thus, by using 1,2,5-ETM which is a polycarboxylic acid containing one carboxyl group which becomes a steric hindrance in the reaction with isocyanate, a large number of free carboxyl groups remain. A paint can be obtained. And since this free carboxyl group can become a crosslinking point at the time of baking, it is thought that the film | membrane with high crosslinking density and excellent in softening resistance can be formed. On the other hand, as the content of 1,2,5-ETM increases, the reaction slows down, so the polyamideimide resin production time, that is, the paint production time becomes longer. As will be described later, since the reaction temperature for producing polyamideimide is about 120 to 150 ° C., this is disadvantageous not only in productivity but also in energy, and causes an increase in production cost. Therefore, it is not preferable. Therefore, 1,2,5-ETM is 0.03 equivalents or more per equivalent of acid component, preferably 0.04 equivalents or more, more preferably 0.06 equivalents or more, and even more preferably 0.08 equivalents or more. .13 equivalent or less, preferably 0.12 equivalent or less. A more preferable combination is 0.97 to 0.87 equivalent of trimellitic anhydride and 0.03 equivalent to 0.13 equivalent of 1,2,5-trimellitic acid as the acid component.

  The number of equivalents of 1,2,5-trimellitic acid here is equivalent to that calculated as bifunctional since 1,2,5-trimellitic acid is considered to function as bifunctional in the reaction with isocyanate. Shows the number.

The acid component and the diisocyanate component are blended so that the equivalent ratio (diisocyanate / acid) is greater than 1 to 1.3, preferably 1.03 to 1.3, more preferably 1.05 to 1.3. It is.
By mixing and reacting the isocyanate component in an excess state with respect to the acid component, the reaction proceeds faster, and as a result, the production time of the polyamide-imide paint can be shortened. As described above, this is significant in that it prevents a decrease in productivity and an increase in production cost due to a delay in the reaction rate accompanying an increase in the content of 1,2,5-ETM.

  As described above, the polyamide-imide resin paint of the present invention can be produced by blending an acid component and a diisocyanate component and using the same production method as that of a conventional polyamide-imide paint. That is, it can be obtained by dissolving the isocyanate component and the acid component in a suitable organic solvent and heating to cause a polymerization reaction. Examples of the organic solvent used include N-methyl-2-pyrrolidone. The organic solvent is preferably used after dehydration.

  The polymerization reaction can be carried out by mixing the raw material components in an organic solvent, gradually increasing the temperature, reaching a certain temperature, and then maintaining the same temperature. The reaction temperature is 120-150 ° C. When the temperature is lower than 120 ° C., the reaction does not proceed. When the temperature exceeds 150 ° C., free carboxyl groups tend to participate in the reaction with isocyanate regardless of the steric hindrance of 1,2,5-ETM.

  Although reaction time is not limited, it is preferable to carry out until the viscosity of the solution becomes 2500 cps or more when the solid content concentration (nonvolatile content concentration) is 27 mass% by dilution. The reaction is preferably stopped by lowering the temperature by adding or diluting a poor solvent such as xylene or DMF.

  Although the temperature drop by the poor solvent may be lowered to room temperature, it is preferable to lower the temperature to about 70 ° C. and then add alcohol to lower the temperature to room temperature. Examples of the alcohol used herein include lower alcohols having about 2 to 6 carbon atoms such as ethanol, propanol, isopropanol and butanol; aromatic alcohols such as benzyl alcohol; phenols such as phenol and cresol. The amount of alcohol added is preferably the amount necessary to block the isocyanate. By adding such an alcohol, it is possible to block an isocyanate group that has become free due to excessive mixing. Thereby, the obstacle at the time of making free isocyanate excessive can be solved. That is, it is possible to eliminate the disadvantages caused by the free excess isocyanate, such as the paint thickening during storage, resulting in a shortened pot life of the paint and reduced storage stability.

  The polyamideimide resin paint of the present invention may further contain various additives such as pigments, dyes, inorganic or organic fillers, and lubricants as necessary. These additives are preferably blended as appropriate after completion of the reaction between the isocyanate and the acid.

  The polyamideimide resin paint of the present invention obtained as described above has a crosslinking density because unreacted carboxyl group derived from 1,2,5-ETM becomes a reaction point at the time of baking and reacts with isocyanate at the polymer terminal. Can form a high film.

The insulated wire of the present invention uses the polyamideimide resin paint of the present invention as an insulating coating.
A metal conductor such as a copper wire or an aluminum wire is used as the conductor.

  The polyamide-imide resin paint of the present invention is applied to the surface of the conductor, and an insulating film is formed by baking. Application | coating and baking can be performed by the method and conditions similar to formation of the insulation film of the conventional insulated wire. The coating and baking process may be repeated twice or more. In addition, the polyamide-imide resin paint of the present invention can be blended with other resin paints as long as the gist of the present invention is not impaired.

  Baking of the polyamide-imide resin coating is preferably performed by passing through a furnace at about 350 to 500 ° C. for 5 to 10 seconds per pass. By baking, an insulating film having excellent heat resistance and wear resistance can be obtained.

  From the viewpoint of protecting the conductor, the thickness of the insulating film is preferably 1 to 100 μm, more preferably 10 to 50 μm. This is because if the insulating coating becomes too thick, the outer diameter of the insulated wire increases, and as a result, the space factor of the coil in which the insulated wire is wound tends to decrease.

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

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

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

[Measurement evaluation method]
First, the evaluation method performed in this example will be described.
(1) Paint production time (hours)
After all the blending components are blended, the temperature is raised from 80 ° C. to 140 ° C. over 4 hours until the viscosity becomes 2500 cps when diluted to 27% by dilution with xylene (polyamideimide resin having a nonvolatile content of 27%) The time until the paint was obtained was measured.

(2) Adhesion According to JIS C3003 “8.1a) Rapid extension”, the produced insulated wire is cut by rapid extension, and the length (mm) and the cut part of the film floating of the uncut portion are cut. The length (mm) of the conductor exposed by peeling off the coating was measured. As the measured value is smaller, the coating layer is not peeled off even on the rapidly extending cut surface, indicating that the adhesiveness is excellent.

(3) Flexibility The insulated wire was stretched by 20% with respect to the initial length, and after stretching, it was tested according to JIS C3003 7.1.1 flexibility test. Specifically, after winding the electric wire 30 times so that the electric wire and the electric wire are in contact with each other along a round bar having a self-diameter (1d) of the insulated electric wire, the presence or absence of cracks was observed and the number of cracks was counted. .
The number of cracks after winding was also counted in the same manner for the diameter of the round bar to be wound twice (2d), 3 times (3d) and 4 times (4d) of the self-diameter of the insulated wire.

(4) Impact resistance The insulated wire was stretched by 20% with respect to the initial length, and after stretching, it was tested according to the impact resistance test of JIS C3003-20. Specifically, after heating at 240 ° C. for 1 hour, after winding the wire 30 times so that the wire and the wire are in contact with each other along a round bar having the self-diameter (1d) of the insulated wire, there is no crack The number of cracks was counted.
The number of cracks after winding was also counted in the same manner for the diameter of the round bar to be wound twice (2d), 3 times (3d) and 4 times (4d) of the self-diameter of the insulated wire.

(5) Abrasion resistance The unidirectional wear value (g) was measured according to the abrasion resistance test described in JIS C3003-1999.

(6) Dielectric breakdown voltage Create a stranded wire using the two insulated wires produced, measure the dielectric breakdown voltage (V) according to JIS C2002 10, and average the measured values of 10 samples. The average breakdown voltage was determined.

(7) Softening temperature The softening temperature (° C) was measured according to JIS C3003 "Test method for enameled copper wire and enameled aluminum wire". For each of the load (700 g) and double load (1400 g) specified in JIS, the temperature (softening temperature) when the electric wire was conducted was measured. It shows that it is excellent in heat resistance, so that softening temperature is high.

[Manufacture of polyamide-imide resin paint and insulated wires]
No. 1:
A separable flask (three necks) and a condenser tube are set in a mantle heater with a temperature rise control function, and 144 g (1 equivalent) of TMA (trimellitic anhydride, manufactured by Mitsubishi Gas Chemical Co., Ltd.) is added, and MDI (diphenylmethane- 4,4′-diisocyanate) and NM2P (N-methyl-2-pyrrolidone solvent, Mitsubishi Chemical) as a solvent so that the concentration of the reaction components (acid component and isocyanate component) is 35% by mass. 948 g of dehydrated and distilled under nitrogen) was completely dissolved at 80 ° C., and then the temperature of the system was gradually raised to 140 ° C. over about 4 hours. Thereafter, the reaction was continued at 140 ° C. until the viscosity was 2500 cps when diluted with xylene to a non-volatile content of 27% by mass. The reaction time (production time) is as shown in Table 1. The reaction is stopped by adding xylene and lowering the temperature by dilution, and the final solid content concentration of the polyamideimide paint is 27% by mass.

The obtained polyamide-imide resin paint was applied to a copper wire having a diameter of 1 mm and then baked by passing through a 350 to 500 ° C. furnace to produce an insulated wire with a film thickness of 0.033 mm.
The adhesion, flexibility, thermal shock resistance, wear resistance, dielectric breakdown voltage, and softening temperature of the prepared insulated wire were measured and evaluated according to the above evaluation methods. The results are shown in Table 1.

No. 2-9:
As an acid component, 5 g (0.03 equivalent), 8 g (0.05 equivalent), 11 g (0.07 equivalent) of polycarboxylic acid (1,2,5-ETM or 1,3,5-ETM), or By adding 17 g (0.11 equivalent) and adjusting the content of TMA and the content of MDI, the acid: isocyanate (equivalent ratio) was changed as shown in Table 1, and the blending amount of NM2P as a solvent was changed to Table 1. Thus, a reaction system having a concentration of 35% by mass was prepared and reacted in the same manner as in No. 1. In addition, after making it react until the viscosity when it is 27 mass% of solid content (nonvolatile content) will be 2500 cps, xylene is added and it cools to 70 degreeC, Furthermore, methanol is added and it was set as the polyamide imide resin coating material. . The solid content concentration of the finally obtained polyamide-imide paint is 27% by mass.

The obtained polyamide-imide resin coating was applied to a copper wire having a diameter of 1 mm (No. 4, 5, 8, 9 is a copper wire having a diameter of 0.998 mm), and then the film thickness was 0.033 mm (only No. 7 was 0. 032 mm) of insulated wire.
The adhesion, flexibility, thermal shock resistance, wear resistance, dielectric breakdown voltage, and softening temperature of the prepared insulated wire were measured and evaluated according to the above evaluation methods. The results are shown in Table 1.

No. 2 is a case where 1,3,5-ETM was used as the polycarboxylic acid component, and the reactivity was too high, resulting in gelation, making it difficult to produce the coating itself.
No. No. 1 is a polyamide-imide resin paint synthesized without containing 1,2,5-ETM. 3-9 are polyamideimide resin paints synthesized by containing 1,2,5-ETM. The softening temperature of the insulating coating formed is No. No. 1 is about 400 ° C. 3 to 9 were all 450 ° C. or higher under JIS load.
No. Comparing 3,4,6,8, it can be seen that the higher the content ratio of 1,2,5-ETM, the higher the softening resistance. The higher the content ratio of 1,2,5-ETM, the longer the production time. From 5, 7, and 9, the production time could be shortened by increasing the ratio of isocyanate to acid component in the reaction components.
In addition, when the 1,2,5-ETM content is low, when the production time is shortened (when the acid / isocyanate equivalent ratio is more than 1), the adhesion represented by unidirectional wear tends to be slightly inferior. (Nos. 5 and 7), when 1,2,5-ETM content is 0.11 equivalent, both unidirectional wear and softening temperature are acid: isocyanate (equivalent ratio), that is, acid / isocyanate is It was confirmed that the characteristics were equal to or higher than those of 1.

  The polyamide-imide resin coating material of the present invention is a polyamide-imide resin coating material that shortens the manufacturing time and has better softening resistance than before, and can reduce production, energy saving, and cost reduction, and can also be used in recent years for insulated wires. It is possible to provide an insulated wire that can meet the stricter demand for softening resistance.

Claims (6)

In a polyamide-imide resin paint obtained by reacting a diisocyanate component with a carboxylic acid component containing trimellitic anhydride and 1,2,5-trimellitic acid,
The 1,2,5-trimellitic acid contains 0.03 equivalents to 0.13 equivalents in the acid component,
The polyamide-imide resin coating material having an equivalent ratio of the diisocyanate component to the carboxylic acid component (diisocyanate / acid) of more than 1 to 1.3. The content of the 1,2,5-trimellitic acid in the acid component is 0.04 equivalents to 0.13 equivalents, and the equivalent ratio of the diisocyanate component to the carboxylic acid component (diisocyanate / acid) is 1. The polyamide-imide resin paint according to claim 1, which is 03 to 1.3. The polyamideimide resin according to claim 1 or 2, wherein excess isocyanate groups are blocked with alcohol. An acid component containing 0.97 to 0.87 equivalents of trimellitic anhydride and 0.03 equivalents to 0.13 equivalents of 1,2,5-trimellitic acid;
A diisocyanate component,
The equivalent ratio of the carboxylic acid component and the diisocyanate component (diisocyanate / acid) is blended so that it is more than 1 to 1.3,
The polyamide according to claim 1, wherein the reaction is performed at about 120 to 150 ° C until the viscosity of the solution having a non-volatile content concentration of 27 mass% by dilution is 2500 cps or more, and then diluted by addition of an organic solvent to lower the temperature. Manufacturing method of imide resin paint. The manufacturing method of Claim 4 including the process of adding alcohol after temperature-fall. An insulated wire comprising a conductor and an insulating coating covering the conductor,
The insulated wire which has an insulating layer formed by baking after the said insulating coating coats the polyamide-imide resin coating material in any one of Claims 1-3.