WO2017110188A1

WO2017110188A1 - Aqueous dispersion type electrodeposition liquid for insulating-film formation

Info

Publication number: WO2017110188A1
Application number: PCT/JP2016/078424
Authority: WO
Inventors: 洵子磯村; 慎太郎飯田; 桜井　英章
Original assignee: 三菱マテリアル株式会社
Priority date: 2015-12-22
Filing date: 2016-09-27
Publication date: 2017-06-29

Abstract

This aqueous dispersion type electrodeposition liquid for insulating-film formation comprises polymer particles, an organic solvent, a basic compound, and water, and is characterized in that the polymer particles are a polyamide-imide and that the basic compound is a nitrogenous compound having an HSP distance of 35 or greater with respect to water .

Description

Electrodeposition solution for water-dispersed insulation film formation

The present invention relates to a water-dispersed insulating film forming electrodeposition liquid used when an insulating film provided in an insulator such as an insulated wire is formed by an electrodeposition method.
This application claims priority based on Japanese Patent Application No. 2015-249739 filed in Japan on December 22, 2015 and Japanese Patent Application No. 2016-166752 filed in Japan on August 29, 2016. The contents are incorporated herein.

Conventionally, an insulator such as an insulated wire whose surface is covered with an insulating film is used for a motor, a reactor, a transformer, and the like. As a method for forming an insulating film on the surface of an electric wire, a dipping method, an electrodeposition method (electrodeposition coating), or the like is known. The dipping method is a method of forming an insulating film having a desired film thickness by, for example, using a rectangular conductive wire or the like as an object to be coated, dipping it in a paint, pulling it up, and repeatedly drying it. . On the other hand, the electrodeposition method deposits charged paint particles on the object to be coated by applying a direct current to the object to be coated immersed in the electrodeposition paint (electrodeposition liquid) and the electrode inserted in the electrodeposition paint. This is a method of forming an insulating film.

The electrodeposition method is attracting attention because it is easier to apply with a uniform film thickness than other methods, and it can form an insulating film with high rust prevention and adhesion after baking. Improvements have been made. For example, as a paint used in the electrodeposition method, particles of a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule, and having a predetermined average particle size and particle size distribution A suspension type polyimide electrodeposition coating material in which is dispersed is disclosed (for example, see Patent Document 1). This electrodeposition paint has excellent storage stability that is difficult to change even after long-term storage, and by using this electrodeposition paint, an electrodeposition film with high uniformity of film properties can be formed at a high electrodeposition rate. It is supposed to be possible.

In addition, as an electrodeposition material used for the electrodeposition method, an electrodeposition material containing a polyamideimide material as a main component and introducing polydimethylsiloxane into the molecular chain of the polyamideimide material is disclosed ( For example, see Patent Document 2.) According to this electrodeposition material, since the polyamideimide-based material having a predetermined molecular structure is used, the heat resistance particularly required for the coating of sliding members and the like can be imparted. It is said that cracking of the film can be suppressed.

In the above-mentioned conventional patent document 1, since the polyimide particles having an anionic group in the molecule are used, the surface potential of the particles is large, and the dispersibility is increased by the electrostatic repulsive force between the particles. Therefore, even if the prepared electrodeposition liquid is stored for several days, the occurrence of particle aggregation or sedimentation is suppressed. However, since it is necessary to use a diamine having a carboxyl group or a sulfonic acid group, or a tetracarboxylic acid anhydride having a carboxyl group or a sulfonic acid group that does not contribute to an imide bond, the types of monomers that can be used are limited. As a result, the manufacturing cost increases. Moreover, in the above-mentioned conventional patent document 2, water-soluble polyamideimide is used for the resin, and a continuous film insoluble in water is formed on the conductor surface during electrodeposition. For this reason, if the formation of the film proceeds to some extent, the subsequent electrodeposition efficiency is deteriorated, and it is difficult to form an insulating film having a desired thickness.

Regarding the problems of such conventional techniques, the present inventors have developed a new electrodeposition liquid having excellent dispersion stability while using polymer particles having no anionic group in the main chain so far. Is engaged in. Polymer particles that do not have an anionic group have no surface property because they do not have an anionic group, and the electrostatic repulsive force between particles becomes small, so the dispersibility in the electrodeposition liquid deteriorates and the particles aggregate. Or, there is a concern that it will easily settle. With respect to such problems, the newly developed electrodeposition liquid ensures good dispersibility of the polymer particles in the electrodeposition liquid by controlling the average particle size and particle size distribution of the polymer particles under predetermined conditions. Thus, even when stored for several days, the occurrence of aggregation or sedimentation of polymer particles is suppressed.

Japanese Patent No. 5555063 JP 2002-20893 A

On the other hand, in developing the above electrodeposition solution, a new problem emerged regarding the storage stability of the electrodeposition solution, which is different from the above-mentioned problem of aggregation or sedimentation of polymer particles. For example, if the electrodeposition liquid stored for several days is used and the coating amount of the electrodeposition liquid is increased to form a relatively thick insulating film, the viscosity of the electrodeposition liquid increases during storage. Thus, it was found that foaming is likely to occur during drying or baking of the coating film. For this reason, there has been a problem that it becomes difficult to form an insulating film having a desired thickness using the electrodeposition liquid after storage. Therefore, there has been a demand for early development of an electrodeposition solution that can overcome such new problems relating to storage stability.

An object of the present invention is a water-dispersed insulating film that is excellent in storage stability, can suppress an increase in the viscosity of an electrodeposition solution even after long-term storage, and can suppress foaming during drying or baking of the coating film It is to provide a forming electrodeposition liquid.

As a result of further earnest studies on the above-mentioned new problems relating to storage stability, the present inventors have found that compounds that are usually contained in the electrodeposition liquid and that have specific properties particularly in other components than the polymer particles As a result, the electrodeposition solution that can solve these problems has been developed.

According to a first aspect of the present invention, in the electrodeposition liquid for forming a water-dispersed insulating film containing polymer particles, an organic solvent, a basic compound and water, the polymer particles are polyamideimide, and the basic compound is water. It is a nitrogen-containing compound having an HSP distance of 35 or more.

The second aspect of the present invention is an invention based on the first aspect, wherein the basic compound is an alkylamine compound.

The electrodeposition liquid for forming a water-dispersed insulating film according to the first aspect of the present invention contains polymer particles, an organic solvent, a basic compound and water, the polymer particles are polyamideimide, and the basic compound is water and Is a nitrogen-containing compound having an HSP distance of 35 or more. Thereby, the storage stability of the electrodeposition liquid is improved, the increase in the viscosity of the electrodeposition liquid is suppressed even when stored for a long time, and foaming can be suppressed from occurring during drying or baking of the coating film.

The electrodeposition liquid for forming a water-dispersed insulating film according to the second aspect of the present invention can further enhance the effect of improving the storage stability of the electrodeposition liquid because the basic compound is an alkylamine compound.

It is the figure which represented typically the electrodeposition coating apparatus of embodiment of this invention.

Next, modes for carrying out the present invention will be described with reference to the drawings. This electrodeposition liquid for forming a water dispersion type insulating film contains polymer particles, an organic solvent, a basic compound and water. A poor solvent may be contained in addition to water.

<Polymer particles>
The polymer particles contained in the electrodeposition liquid are composed of polyamideimide which is a polymer (polymer). The reason why particles made of polyamideimide are used as polymer particles is that heat resistance and flexibility are superior to other polymer particles.

The average particle diameter of the polymer particles is not particularly limited from the viewpoint of suppressing foaming during drying or firing, and those having a particle diameter used for general electrodeposition liquid applications can be used. For example, polymer particles having an average particle diameter of preferably 0.05 to 1.0 μm can be used. The average particle diameter of the polymer particles referred to here is a volume-based median diameter (D ₅₀ ) measured by a dynamic light scattering type particle size distribution analyzer (model name: LB-550, manufactured by Horiba, Ltd.). Say.

About the polyamideimide which comprises a polymer particle, the polyamideimide etc. which are used for the general electrodeposition liquid use can be utilized as resin which comprises the said polymer particle. For example, it may be a polyamideimide having an anionic group in the main chain, or a polyamideimide having no anionic group in the main chain. The anionic group, as such -COOH group (carboxyl group) or -SO ₃ H (sulfonic acid group), in a basic solution such as proton is eliminated -COO ^- nature take on negative charge of such group A functional group having If polymer particles composed of polyamideimide having an anionic group in the main chain are used, a large electrostatic repulsive force is obtained between the particles due to the high surface potential of the polymer particles, and the dispersibility in the electrodeposition liquid is improved. And the aggregation or sedimentation of polymer particles is suppressed even when stored for several days.

Therefore, it is desirable that the polyamideimide constituting the polymer particle has an anionic group in the main chain in order to suppress aggregation or sedimentation of the polymer particle. However, from the viewpoint of suppressing foaming, the polyamideimide particularly has an anionic group. It is not limited to things. In addition, polyamideimide having an anionic group in the main chain needs to use a monomer having an anionic group as a monomer used for the synthesis, and the usable monomer is limited, so that the production cost increases. There is. For this reason, in order to reduce the cost, it is desirable to use polymer particles composed of polyamideimide having no anionic group in the main chain.

On the other hand, polymer particles composed of polyamideimide having no anionic group in the main chain exhibit a relatively small surface potential. Therefore, dispersibility due to electrostatic repulsion between particles may not be sufficiently obtained, but dispersibility can be enhanced by controlling the particle size, particle size distribution, and the like. For this reason, in addition to suppressing foaming, it is desirable to more strictly control the particle size and particle size distribution of polymer particles in consideration of dispersibility when further reducing costs and suppressing aggregation or sedimentation. When polymer particles having no anionic group in the main chain are used, the volume-based median diameter (D ₅₀ ) is 0.05 to 0.5 μm, and the particle diameter is ±± of the median diameter (D ₅₀ ). The particles within 30% are preferably 50% (volume basis) or more of all particles. That is, the polymer particles have a median diameter (D ₅₀ ) in the range of 0.05 to 0.5 μm when the volume-based particle size distribution of the powder comprising the particles is measured, Particles of 50% or more of the number of particles are distributed within a range of ± 30% of the median diameter (D ₅₀ ) (within a range of [D ₅₀ -0.3D ₅₀ ] μm to [D ₅₀ + 0.3D ₅₀ ] μm). To do. The volume-based median diameter (D ₅₀ ) and the proportion of particles distributed within a range of ± 30% of the median diameter (D ₅₀ ) (volume basis) are both dynamic light scattering particle size distribution measuring devices ( This is based on the volume-based particle size distribution measured by HORIBA, Ltd. (model name: LB-550). Further, the polyamideimide having no anionic group in the main chain means a polyamideimide having no anionic group at least on carbon atoms other than the end of the main chain. The reason why the volume-based median diameter (D ₅₀ ) of the polymer particles having no anionic group in the main chain is preferably in the above range is that if this volume-based median diameter (D ₅₀ ) is too small, it will be described later. This is because the polymer particles may form a continuous film during electrodeposition when forming the insulating layer, and the electrodeposition efficiency gradually decreases, making it difficult to increase the thickness of the insulating layer. In addition, by controlling the volume-based median diameter (D ₅₀ ), even if the formation of the insulating layer proceeds to some extent by electrodeposition, the subsequent current flow can be easily maintained. The reason is that conductive water contained in the solvent tends to exist between the polymer particles. On the other hand, if the volume-based median diameter (D ₅₀ ) becomes too large, precipitation may occur in the electrodeposition solution stored for several days. The reason why the proportion of particles distributed within a range of ± 30% of the volume-based median diameter (D ₅₀ ) is preferably 50% or more is that even if the proportion of the particles is too small, it is stored for several days. This is because precipitation may occur in the deposited electrodeposition solution. Among these, polymer particles having no anionic group have a volume-based median diameter (D ₅₀ ) of 0.08 to 0.25 μm and are distributed within a range of ± 30% of the median diameter (D ₅₀ ). The proportion of particles is more preferably 75% or more.

Polyamideimide constituting polymer particles is a reaction product (resin) obtained by polymerizing a diisocyanate component containing an aromatic diisocyanate component and an acid component containing trimellitic anhydride, etc., as monomers. It is.

Examples of the diisocyanate component include diphenylmethane-4,4′-diisocyanate (MDI), diphenylmethane-3,3′-diisocyanate, diphenylmethane-3,4′-diisocyanate, diphenylether-4,4′-diisocyanate, and benzophenone-4,4 ′. And aromatic diisocyanates such as diisocyanate and diphenylsulfone-4,4′-diisocyanate.

The acid component includes trimellitic anhydride (TMA), 1,2,5-trimellitic acid (1,2,5-ETM), biphenyltetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride , Diphenylsulfonetetracarboxylic dianhydride, oxydiphthalic dianhydride (OPDA), pyromellitic dianhydride (PMDA), 4,4 '-(2,2'-hexafluoroisopropylidene) diphthalic dianhydride An aromatic acid anhydride such as

The polyamide-imide resin varnish can be obtained by mixing the diisocyanate component and the acid component in equal amounts and heating in an organic solvent to cause a polymerization reaction. In addition, the said isocyanate component and an acid component may each be used individually, and may be used combining several types.

Moreover, it is preferable that the polyamideimide constituting the polymer particles does not have a siloxane bond. This is because if the siloxane bond is present, the siloxane bond is likely to be thermally decomposed, so that the heat resistance of the insulating film may be deteriorated. Since the presence or absence of a siloxane bond results from the use of a monomer containing a siloxane bond, a polymer having no siloxane bond can be obtained by using a monomer that does not contain a siloxane bond.

<Organic solvent, water, poor solvent>
Organic solvents include 1,3-dimethyl-2-imidazolidinone (DMI), N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, tetramethylurea, hexa Polar solvents such as ethyl phosphoric acid triamide and γ-butyrolactam can be used. Examples of water include pure water, ultrapure water, and ion exchange water. When a poor solvent is contained in addition to water, examples of the poor solvent include aliphatic alcohols such as 1-propanol and isopropyl alcohol, ethylene glycols such as 2-methoxyethanol, 1-methoxy-2-propanol, and the like. Propylene glycols or the like can be used.

<Basic compound (dispersing agent or neutralizing agent)>
The basic compound is a component added to the electrodeposition liquid as a neutralizing agent or a dispersing agent, and a nitrogen-containing compound having an HSP distance of 35 or more with water is used as the basic compound. Here, HSP (Hansen Solubility Parameter) is a value used as a solubility index indicating how much a certain substance is dissolved in a certain substance. This HSP value is composed of three parameters of a dispersion term (dD), a polarity term (dP), and a hydrogen bond term (dH), and shows a unique value for each substance. Since these three parameters can be regarded as coordinates in a three-dimensional space (Hansen space), the HSP value is represented as a vector having 0 in the space as the start point and the coordinate given by the HSP value as the end point. The HSP distance (Ra) is a distance between the coordinates or a vector distance given by the HSP values of two substances, and is generally calculated by the following equation (1).

HSP distance = [4 × (dD ₁ −dD ₂ ) ² + (dP ₁ −dP ₂ ) ² + (dH ₁ −dH ₂ ) ² ] ^1/2 (1)

In the above formula (1), dD ₁ , dP ₁ and dH ₁ are HSP values of one of the two substances, and dD ₂ , dP ₂ and dH ₂ are HSP values of the other substance. It shows that the compatibility between the two substances is higher as the substances having a smaller HSP distance calculated by the equation (1). The nitrogen-containing compound having an HSP distance of 35 or more with water means that the HSP value of water (dD = 15.5, dP = 16, dH = 42.3) and the HSP value of the nitrogen-containing compound are expressed in the above formula (1). A nitrogen-containing compound having a value (HSP distance) calculated by substitution of 35 or more.

The storage stability of the electrodeposition liquid can be improved by using, as the basic compound contained in the electrodeposition liquid, a nitrogen-containing compound having an HSP distance with water of a predetermined value or more. Thereby, even if the electrodeposition liquid after preparation is preserve | saved for a long period, the viscosity raise of an electrodeposition liquid etc. are suppressed, and it can suppress that foaming arises at the time of drying or baking of a coating film, and a film thickness falls. The technical reason that the storage stability of the electrodeposition solution is improved by using a nitrogen-containing compound having such physical property values has not been elucidated at present, but the following technical reasons are the main technical reasons. Inferred as The basic compound functions to enhance the dispersibility of the electrodeposition liquid by binding in the polymer structure. If the basic compound is hydrophilic, such as 2-aminoethanol, the water in the electrodeposition solution tends to approach the polymer particles, so that the polyamideimide is easily hydrolyzed. When the polyamideimide is hydrolyzed, polar groups such as carboxyl groups and amino groups are generated, so the viscosity of the liquid rises by attracting polar solvents such as DMI and water, and the polymer takes in the solvent and partially gels. Can be considered. On the other hand, when using a basic compound having a large HSP distance with water and low affinity with water, that is, having a high hydrophobicity, it is difficult to bring water close to the polymer particles. It is thought that change can be suppressed. The upper limit is not particularly limited as long as the HSP distance to water reaches at least 35, but the HSP distance to water is 35 to 45 from the relationship with the HSP value of the nitrogen-containing compound that can be confirmed at present. Are preferred.

Specific examples of nitrogen-containing compounds which exhibit such physical property values and are suitable as basic compounds contained in the electrodeposition liquid include alkylamine compounds. Furthermore, examples of the alkylamine compound include primary alkylamines such as propylamine, butylamine, amylamine, hexylamine, octylamine and decylamine, and second alkylamines such as dipropylamine, dibutylamine, diamylamine, dihexylamine and dioctylamine. Tertiary alkylamines such as tertiary alkylamine, tripropylamine, tributylamine, triamylamine, and trihexylamine are listed. Of these, tripropylamine, tributylamine, triamylamine, trihexylamine, and the like are particularly preferable because of their large HSP distance with water and high hydrophobicity.

<Preparation of electrodeposition solution>
The electrodeposition liquid can be obtained, for example, by the following method. First, a polyamideimide resin varnish is synthesized using a diisocyanate component, an acid component, and an organic solvent as described above. Specifically, the diisocyanate component and the acid component as monomers are respectively prepared, and together with these, an organic solvent such as DMI is introduced into the flask at a predetermined ratio. The flask is preferably a four-necked flask equipped with a stirrer, a cooling pipe, a nitrogen introduction pipe, a thermometer, and the like. The mixing ratio of the diisocyanate component and the acid component is preferably set to a ratio of 1: 1 as a molar ratio. The proportion of the organic solvent is preferably a proportion corresponding to 1 to 3 times the mass of the resin obtained after synthesis. After putting them into the flask, the temperature is preferably raised to a temperature of 80 to 180 ° C., and the reaction is preferably carried out for 2 to 8 hours.

Thereafter, if necessary, by diluting with the above-mentioned organic solvent, a polyamideimide resin varnish containing a polyamideimide resin synthesized as a non-volatile content, preferably in a proportion of 20 to 50% by mass, is obtained.

In order to prepare a water-dispersed insulating film-forming electrodeposition solution from the polyamideimide resin varnish synthesized as described above, the prepared polyamideimide resin varnish is further diluted with the organic solvent as necessary, The above-mentioned basic compound is added as a dispersant or neutralizer. At this time, a poor solvent may be added as necessary. Then, while stirring at a rotational speed of preferably 8000 to 12000 rpm, water is added and dispersed sufficiently at room temperature. When a poor solvent is added, the preferred proportion of each component in the electrodeposition solution is polyamideimide resin / organic solvent / poor solvent / water / basic compound = 1 to 10% by mass / 60 to 79% by mass / balance. / 10 to 20% by mass / 0.05 to 0.3% by mass.

Through the above steps, the above-mentioned electrodeposition liquid for forming a water-dispersed insulating film is obtained.

<Manufacture of insulators>
Subsequently, an example of a method for manufacturing an insulated wire in which an insulating film is formed on the surface of an electric wire is described as an example of a method for manufacturing an insulator in which an insulating film is formed on a metal surface using the water-dispersed insulating film forming electrodeposition liquid. Will be described with reference to the drawings. As shown in FIG. 1, the electrodeposition coating apparatus 10 is used to electrodeposit the electrodeposition liquid 11 on the surface of the electric wire 12 by an electrodeposition coating method to form an insulating layer 21a. Specifically, a cylindrical electric wire 13 having a circular cross section that is wound in a cylindrical shape is electrically connected in advance to the positive electrode of the DC power source 14 via the anode 16. And this cylindrical electric wire 13 is pulled up in the direction of the solid line arrow of FIG. 1, and passes through each next process.

First, as a first step, a cylindrical electric wire 13 is rolled flat by a pair of rolling

rollers

17 and 17 to form a rectangular electric wire 12 having a rectangular cross section. Examples of the electric wire include a copper wire, an aluminum wire, a steel wire, a copper alloy wire, and an aluminum alloy wire. Next, as a second step, the electrodeposition liquid 11 is stored in the electrodeposition tank 18 and is preferably maintained at a temperature of 5 to 60 ° C. so that the electrodeposition liquid 11 in the electrodeposition tank 18 has a rectangular shape. The electric wire 12 is passed. Here, a cathode 19 that is electrically connected to the negative electrode of the DC power supply 14 is inserted into the electrodeposition liquid 11 in the electrodeposition tank 18 with a space from the flat rectangular wire 12 passing therethrough. When the rectangular electric wire 12 passes through the electrodeposition liquid 11 in the electrodeposition tank 18, a DC voltage is applied between the rectangular electric wire 12 and the cathode 19 by the DC power source 14. At this time, the DC voltage of the DC power supply 14 is preferably 1 to 300 V, and the DC current application time is preferably 0.01 to 30 seconds. As a result, in the electrodeposition liquid 11, negatively charged polymer particles (not shown) are electrodeposited on the surface of the flat wire 12 to form the insulating layer 21 a.

Next, an insulating film 21b is formed on the surface of the electric wire 12 by subjecting the flat electric wire 12 having the insulating layer 21a electrodeposited on the surface thereof to a baking treatment. In this embodiment, the electric wire 12 having the insulating layer 21a formed on the surface thereof is baked by passing through the baking furnace 22. The baking treatment is preferably performed by a near infrared heating furnace, a hot air heating furnace, an induction heating furnace, a far infrared heating furnace, or the like. The temperature of the baking treatment is preferably in the range of 250 to 500 ° C., and the time of the baking treatment is preferably in the range of 1 to 10 minutes. Note that the temperature of the baking treatment is the temperature of the central portion in the baking furnace. By passing through the baking furnace 22, an insulated wire 23 in which the surface of the wire 12 is covered with an insulating film 21b is manufactured.

Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
In a 2 liter four-necked flask equipped with a stirrer, a condenser, a nitrogen inlet tube and a thermometer, 30.97 g of 1,3-dimethyl-2-imidazolidinone (DMI), diphenylmethane-4,4′-diisocyanate 508 g (30 mmol) and trimellitic anhydride 5.764 g (30 mmol) were charged, and the temperature was raised to 160 ° C. By reacting for about 6 hours, a polymer (polyamideimide resin) having a number average molecular weight of 40,000 was synthesized, and a polyamideimide varnish (polyamideimide resin / DMI = 30 mass) having a polyamideimide resin (nonvolatile content) concentration of 30 mass%. % / 70 mass%).

Next, 1.7 g of the polyamideimide varnish obtained above was further diluted with 4.8 g of DMI. After adding 1.7 g of 1-methoxypropanol as a poor solvent and 0.02 g of tripropylamine as a basic compound, While stirring at a high speed of 10,000 rpm, 1.8 g of water was added at room temperature (25 ° C.). Thereby, the electrodeposition liquid in which the polyamideimide fine particles are dispersed (polyamideimide resin / DMI / poor solvent / water / basic compound = 5 mass% / 60 mass% / 17 mass% / 18 mass% / 0.2 mass%) Got.

<Examples 2 to 7 and Comparative Example 1>
As shown in Table 1 below, the electrodeposition solution was prepared in the same manner as in Example 1 except that the average particle diameter of the polymer particles, the type of the basic compound, and the ratio of each component in the electrodeposition solution were changed. Obtained. The average particle diameter of the polymer particles is a numerical value obtained by changing the ratio of other liquid components, and is a volume-based median diameter (D ₅₀ ) described later.

<Comparison test and evaluation>
The following (i) to (iii) were evaluated for the electrodeposition solutions obtained in Examples 1 to 7 and Comparative Example 1. These results are shown in Table 1 or Table 2 below.

(i) HSP distance from flooded water: By substituting the HSP value of water and the HSP value of the nitrogen-containing compound used as the basic compound in each Example or Comparative Example, into the following formula (1), The HSP distance of the contained compound and water was calculated respectively. As the HSP value of the nitrogen-containing compound, an HSP value obtained by software capable of calculating the HSP value from the structural formula of the substance (software name: Hansen Solubility Parameter in Practice (HSPIP)) was used.

(ii) Volume-based median diameter (D ₅₀ ): measured with a dynamic light scattering particle size distribution analyzer (model name: LB-550, manufactured by Horiba, Ltd.) for the polymer particles synthesized in each Example or Comparative Example The volume-based median diameter (D ₅₀ ) was measured.

(iii) Proportion of particles distributed within a range of ± 30% of median diameter (D ₅₀ ): From a volume-based particle size distribution measured by the above apparatus, within a range of ± 30% of median diameter (D ₅₀ ) [[ D ₅₀ -0.3D ₅₀ ] μm to [D ₅₀ + 0.3D ₅₀ ] μm) was calculated as the ratio of the particles distributed to the total number of particles.

(iii) Storage stability: An insulating film was formed on the surface of the copper plate using the electrodeposition liquid immediately after preparation obtained in each of the examples and comparative examples and the electrodeposition liquid stored for one month after adjustment. An insulating material was prepared, and the storage stability of the electrodeposition liquid was evaluated by visually observing the presence or absence of bubbles in the insulating film. In Table 2, “None” indicates that no bubbles were observed in the insulating film. “Present” indicates that one or more bubbles were confirmed in the insulating film.

The insulator was manufactured according to the procedure described later. In each example and comparative example, for each electrodeposition solution, three insulators having an insulating film thickness of 10 μm, 20 μm, and 30 μm, respectively, were prepared. The electrodeposition liquid immediately after the preparation refers to an electrodeposition liquid before 24 hours have passed after the preparation, and the electrodeposition liquid stored for one month after the adjustment means that the adjusted electrodeposition liquid is sealed in a glass bottle. The electrodeposition liquid stored in the atmosphere at a temperature of 25 ° C. for 1 month. The film thickness is a value measured using a micrometer (Mitutoyo Co., Ltd. model name: MDH-25M) after forming an insulating film on the surface of the copper plate.

Each insulator was produced by the following procedure. First, the electrodeposition liquid was stored in the electrodeposition tank, and the temperature of the electrodeposition liquid in the electrodeposition tank was adjusted to 25 ° C. Next, an 18 mm square (thickness: 0.3 mm) copper plate and stainless steel plate were prepared as an anode and a cathode, respectively, and these were placed facing each other in the electrodeposition solution. And the DC voltage 100V was applied between the copper plate and the stainless steel plate, and electrodeposition was performed. At that time, the amount of electricity flowing by the coulomb meter was confirmed, and the application of voltage was stopped when the amount of electricity reached a predetermined amount. When an insulating film having a film thickness of 10 μm is formed, the application of voltage is stopped when the amount of electricity reaches 0.05 C, and when an insulating film having a film thickness of 20 μm is formed, the amount of electricity is 0.1. When the voltage reached 10 C, the application of voltage was stopped. When an insulating film having a film thickness of 30 μm was formed, the voltage application was stopped when the amount of electricity reached 0.15 C. Thereby, an insulating layer was formed on the surface of the copper plate.

Next, the copper plate having an insulating layer formed on the surface was baked. Specifically, the copper plate on which the insulating layer was formed was held for 3 minutes in a baking furnace maintained at a temperature of 250 ° C. Thereby, an insulator having an insulating film formed on the surface of the copper plate was obtained. In addition, the temperature in a baking furnace is the temperature of the center part in a furnace measured with the thermocouple.

As is apparent from Tables 1 and 2, when the electrodeposition liquid immediately after preparation was used, any insulating film of Examples 1 to 7 and Comparative Example 1 was caused by foaming during drying or firing. There were no bubbles.

On the other hand, when comparing the insulating film formed with the electrodeposition liquid stored for one month after the preparation, in Comparative Example 1 using a nitrogen-containing compound whose HSP distance with water is less than a predetermined value as a basic compound, In the insulating film of all film thickness, bubbles were generated due to foaming during drying or firing.

On the other hand, in Examples 1 to 7 using a nitrogen-containing compound whose HSP distance with water is a predetermined value or more as a basic compound, bubbles are formed in the insulating film having a thickness of 30 μm in Examples 2 and 4 to 6. No air bubbles due to foaming at the time of drying or baking were observed in any of the insulating films except that a slight amount of was observed. From this, it was confirmed that the electrodeposition liquids of Examples 1 to 7 using a nitrogen-containing compound having an HSP distance with water as a basic compound of a predetermined value or more are very excellent in storage stability. In particular, in Examples 1 and 7, the HSP distance with water as a basic compound is as large as 43.0 and 42.5, respectively. Therefore, even when the film thickness is 30 μm, bubbles due to foaming during drying or baking are observed. There wasn't.

The present invention can be used for the production of insulated wires used in transformers, reactors, motors, etc. for in-vehicle inverters, as well as power inductors for power supplies of personal computers, smartphones, etc., and other insulators.

11 Electrodeposition solution

Claims

In the electrodeposition liquid for forming a water dispersion type insulating film containing polymer particles, an organic solvent, a basic compound and water,
The polymer particles are polyamideimide;
The electrodeposition solution for forming a water-dispersed insulating film, wherein the basic compound is a nitrogen-containing compound having an HSP distance of 35 or more with water.
The electrodeposition liquid for forming a water-dispersed insulating film according to claim 1, wherein the basic compound is an alkylamine compound.