JP5555063B2 - Polyimide electrodeposition paint and method for producing the same - Google Patents

Description

  The present invention relates to a suspension-type polyimide electrodeposition coating material and a method for producing the same, and particularly has excellent storage stability that does not cause separation even when stored for a long period of time. The present invention relates to a suspension-type polyimide electrodeposition coating material capable of forming a high electrodeposition coating and a method for producing the same.

  Conventionally, the method of coating by electrodeposition of polyimide is electrodeposition after electrodeposition using a water-dispersed electrodeposition solution in which a poor solvent and water are added to an organic polar solvent in which polyamic acid, which is a polyimide precursor, is dissolved. Is known to be heated to 240-260 ° C. to form a polyimide film (Patent Documents 1 to 3). A polyamic acid electrodeposition aqueous dispersion has poor storage stability because the polyamic acid is easily decomposed, and the electrodeposited coating film needs to be subjected to a high temperature treatment for imidization. Moreover, there exists the method of making electrodeposition possible by introduce | transducing carboxylic acid into the polyimide which made the polyamic acid directly imidated like patent document 4. FIG. However, it is not always satisfactory with respect to the difficulty of peeling and cracking of the electrodeposition film. In addition, an electrodeposition coating composition containing a solvent-soluble polyimide and a hydrophilic polymer in the same particle is described in Patent Document 5, and it is also described that diaminoorganosiloxane is used as a diamine component. The difficulty of peeling and cracking of the electrodeposition film cannot be satisfied. Furthermore, Patent Document 6 describes a polyimide silicone resin composition, but this is not an electrodeposition composition, and also uses polyamic acid. There is a problem that requires. Therefore, an electrodeposition coating that can solve such problems of the prior art, has excellent heat resistance, and can form a highly reliable highly insulating electrodeposition film that does not easily peel or crack on the electrodeposit. As a result, the applicant of the present application has proposed a paint mainly composed of a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule (Patent Document 7). However, since this electrodeposition paint consists of a mixed system of several types of solvents, the electrodeposition properties change greatly due to slight fluctuations in the blending ratio of the solvents, and there are large restrictions in terms of the usage environment such as temperature and steam volume. There is a drawback that the electrodeposition coating lacks stability, and the film properties of the formed electrodeposition coating are difficult to be uniform. A suspension type paint in which copolymerized polyimide is dispersed as solid particles was further developed (Patent Document 8). However, such a suspension-type paint has high electrical conductivity during the film growth process, and can form a highly uniform electrodeposition film even under low-current electrodeposition conditions. There is a problem that the storage stability is not sufficient when mass production is assumed, and the solid particles of the precipitated polyimide have a variation in particle size, and have a sharp particle size distribution. It has been difficult to produce a suspension type paint in which polyimide particles are dispersed.

Japanese Patent Laid-Open No. 49-52252 JP 52-32943 A JP-A-63-1111199 JP-A-9-104839 JP 2000-178481 A JP 2003-213129 A Japanese Patent Laid-Open No. 2005-162954 International Publication No. 2008/139990 Pamphlet WO99 / 19771 pamphlet US Pat. No. 5,502,143

  In view of the above circumstances, the problem to be solved by the present invention is an electrodeposition that has excellent storage stability that is difficult to change even after long-term storage, and has extremely high uniformity of film properties at a high electrodeposition rate during use. An object is to provide a polyimide electrodeposition coating material capable of forming a film and a method for producing the same.

In order to solve the above problems, the present invention adopts the following configuration.
(1) A suspension-type polyimide electrodeposition coating in which particles of a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule are dispersed,
The block copolymer polyimide particles measured by laser Doppler method (dynamic / electrophoretic light scattering method) have an average particle diameter of 0.05 to 5 μm and the average particle diameter is D1 (μm). , (D1−0.3 × D1) μm to (D1 + 0.3 × D1) μm, and the particle size distribution falls within 55% (number basis) of the total particle size. Suspension type polyimide electrodeposition paint.
(2) The suspension type polyimide electrodeposition coating composition according to claim 1, wherein the block copolymerized polyimide contains a diamine having a siloxane bond in the molecular skeleton as one of the diamine components.
(3) A diamine having a siloxane bond in the molecular skeleton is bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane, and The suspension-type polyimide electrodeposition coating material according to the above (1) or (2), which is one or more selected from the group consisting of compounds represented by the following general formula (I).

(In the formula, each of four R's independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxy groups, and l and m each represent Independently represents an integer of 1 to 4, and n represents an integer of 1 to 20.)
(4) The suspension-type polyimide electrodeposition coating material according to any one of (1) to (3), wherein the block copolymerized polyimide contains an aromatic diaminocarboxylic acid as one of the diamine components.
(5) The suspension type polyimide according to any one of the above (1) to (4), wherein the anionic group of the block copolymerized polyimide is a carboxylic acid group or a salt thereof, and / or a sulfonic acid group or a salt thereof. Electrodeposition paint.
(6) In the total diamine component of the block copolymerized polyimide, the proportion of diamine having a siloxane bond in the molecular skeleton is 5 to 90 mol%, and the proportion of the aromatic diaminocarboxylic acid is 10 to 70 mol% (however, both The suspension type polyimide electrodeposition coating material according to any one of the above (3) to (5), wherein the total is 100 mol% or less and may contain a third diamine component.
(7) An insulating member having, as an insulating layer, an electrodeposition film made of the electrodeposition paint according to any one of (1) to (6).
(8) A method for producing a suspension-type polyimide electrodeposition coating in which particles of a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule are dispersed,
In a polyimide solution having a siloxane bond in the molecular skeleton and a block copolymerized polyimide having an anionic group in the molecule dissolved in a water-soluble polar solvent, the concentration of the block copolymerized polyimide is 15 to 25% by weight. After blending a poor solvent and a basic compound for the block copolymerized polyimide and neutralizing the block copolymerized polyimide, the amount of change in electrical conductivity per day of the polyimide solution at room temperature is 0.1 mS / leaving the solution until it is less than or equal to m,
A first dilution step in which an amount of water smaller than the amount of the block copolymerized polyimide that can be deposited in the polyimide solution after being left standing is added under stirring;
After the first dilution step, the second dilution step of adding water with stirring to precipitate the block copolymer polyimide,
A method for producing a suspension-type polyimide electrodeposition paint, comprising using a thin-film swirl stirrer as stirring means in the first and second dilution steps.
(9) The method according to (8) above, wherein in the second dilution step, water is added in at least two times.
(10) The compounding amount of the poor solvent is 50 to 300% by weight with respect to the polyimide in the polyimide solution, the compounding amount of the basic compound is an amount such that the polyimide neutralization rate is 70 to 130%, and water The method according to (8) or (9) above, wherein the total input amount is an amount such that the solid content concentration of the paint is 1 to 12% by weight.
(11) The water-soluble polar solvent is N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), γ-butyrolactone (γBL), The method according to any one of (8) to (10) above, comprising one or more selected from anisole, tetramethylurea, and sulfolane.
(12) The method according to any one of (8) to (11) above, wherein the poor solvent of the block copolymerized polyimide is an alkoxy-substituted aliphatic alcohol.
(13) The method according to any one of (8) to (12) above, wherein the basic compound is a basic nitrogen-containing compound.
(14) The method according to (13) above, wherein the basic nitrogen-containing compound is a nitrogen-containing heterocyclic compound.
(15) The method according to any one of (8) to (14) above, wherein the block copolymerized polyimide contains a diamine having a siloxane bond in the molecular skeleton as one of the diamine components.
(16) A diamine having a siloxane bond in the molecular skeleton is bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane, and The method according to (15) above, which is one or more selected from the group consisting of compounds represented by the following general formula (I).

(Wherein, four R's independently represent an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxy groups, and l and m are each independently And represents an integer of 1 to 4, and n represents an integer of 1 to 20.)
(17) The method according to any one of (8) to (16) above, wherein the block copolymerized polyimide contains an aromatic diaminocarboxylic acid as one of the diamine components.
(18) The method according to any one of (8) to (17) above, wherein the anionic group of the block copolymerized polyimide is a carboxylic acid group or a salt thereof, and / or a sulfonic acid group or a salt thereof.
(19) In all diamine components of the block copolymerized polyimide, the proportion of diamine having a siloxane bond in the molecular skeleton is 5 to 90 mol%, and the proportion of aromatic diaminocarboxylic acid is 10 to 70 mol% (however, the total of both) Is 100 mol% or less, and may contain a third diamine component). The method according to any one of (8) to (17) above.

According to the present invention, it is possible to form a polyimide electrodeposition film that is excellent in storage stability and, at the time of use, has a high electrodeposition rate, extremely high uniformity in film properties, and excellent adhesion to the surface of an electrodeposit. A suspension type polyimide electrodeposition coating can be obtained.
Therefore, by using the electrodeposition paint of the present invention, it is possible to produce an insulating member (part) having an insulating coating having both high insulating properties (particularly voltage resistance) and heat resistance at a high yield.

Hereinafter, the present invention will be described with reference to preferred embodiments thereof.
The electrodeposition paint of the present invention has a suspension in which particles of a block copolymerized polyimide having a siloxane bond (—Si—O—) in the molecular skeleton (that is, the main chain of the polyimide) and an anionic group in the molecule are dispersed. Type polyimide electrodeposition paint.

  Here, the “block copolymerized polyimide” is a tetracarboxylic dianhydride and a diamine that are heated to form an imide oligomer (first stage reaction), and then the same as the tetracarboxylic dianhydride described above. Alternatively, a different tetracarboxylic dianhydride or / and a diamine different from the above diamine is added to react (second stage reaction) to prevent random copolymerization caused by exchange reaction between amic acids. It means a copolymerized polyimide obtained.

  In the block copolymer polyimide containing a siloxane bond in the main chain of the polyimide and having an anionic group in the molecule, the siloxane bond in the main chain is a siloxane bond derived from a tetracarboxylic dianhydride component. Although it may be a siloxane bond derived from a diamine component, it is preferably a siloxane bond derived from a diamine component, and usually a diamine having a siloxane bond (-Si-O-) in the molecular skeleton in at least a part of the diamine component. A block copolymerized polyimide obtained using a compound (hereinafter sometimes referred to as “siloxane bond-containing diamine”) is used.

  In the present invention, the siloxane bond-containing diamine can be used without particular limitation as long as it can be imidized with a tetracarboxylic dianhydride. For example, bis (4-aminophenoxy) dimethylsilane, 1,3 -Bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane and the general formula (I):

(Wherein, four R's independently represent an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxy groups, and l and m are each independently And an integer of 1 to 4 and n represents an integer of 1 to 20). The compound represented by the general formula (I) includes a single compound in which n is 1 or 2, and polysiloxane diamine.

  In each of the four Rs in formula (I), the alkyl group and the cycloalkyl group preferably have 1 to 6 carbon atoms, more preferably 1 to 2 carbon atoms. In addition, in the phenyl group substituted with 1 to 3 alkyl groups or alkoxy groups, when 1 to 3 alkyl groups or alkoxy groups are 2 or 3, they may be the same or different from each other. Good. Moreover, as for an alkyl group and an alkoxy group, C1-C6 is respectively preferable, and 1-2 are more preferable.

  In the compound represented by the general formula (I), four Rs in the formula are preferably an alkyl group (particularly a methyl group) or a phenyl group, and in the formula, l and m are 2 to 3, and n is 5 Polysiloxane diamines in ˜15 are preferred.

  Preferred examples of the polysiloxane diamine include bis (γ-aminopropyl) polydimethylsiloxane (in the formula (I), l and m are 3, and four R are methyl groups), bis (γ-amino) Propyl) polydiphenylsiloxane (in the formula (I), l and m are 3, and four R are phenyl groups).

  In the present invention, the siloxane bond-containing diamine may be used alone or in combination of two or more. In addition, a commercial item may be used for this siloxane bond containing diamine, and what is sold from Shin-Etsu Chemical Co., Toray Dow Corning, Chisso can be used as it is. Specifically, KF-8010 (bis (γ-aminopropyl) polydimethylsiloxane: amino group equivalent of about 450) and X-22-161A (bis (γ-aminopropyl) polydimethylsiloxane manufactured by Shin-Etsu Chemical Co., Ltd .: Amino group equivalent of about 840) and the like, and these are particularly preferable.

  In the present invention, the anionic group is a group that becomes an anion in the solvent (described later) of the electrodeposition composition, preferably a carboxyl group or a salt thereof, and / or a sulfonic acid group or a salt thereof. The anionic group may be contained in a siloxane-containing diamine or a tetracarboxylic dianhydride component, but it is preferable to use a diamine having an anionic group as one of the diamine components. Such an anionic group-containing diamine is preferably an aromatic diamine in order to improve the heat resistance of the polyimide, the adhesion to the electrodeposit, and the degree of polymerization. That is, aromatic diaminocarboxylic acid and / or aromatic diaminosulfonic acid is preferable. Examples of the aromatic diaminocarboxylic acid include 3,5-diaminobenzoic acid, 2,4-diaminophenylacetic acid, 2,5-diaminoterephthalic acid, 3,3′-dicarboxy-4,4′-diaminodiphenylmethane, 3,5-diaminoparatoluic acid, 3,5-diamino-2-naphthalene carboxylic acid, 1,4-diamino-2-naphthalene carboxylic acid and the like can be mentioned, and aromatic diaminosulfonic acid includes 2,5-diamino Examples thereof include benzenesulfonic acid, 4,4′-diamino-2,2′-stilbene disulfonic acid, o-tolidine disulfonic acid, and the like. Among these, 3,5-diaminobenzoic acid is particularly preferable. Such an anionic group-containing aromatic diamine may be used alone or in combination of two or more. When the siloxane bond-containing diamine has an anionic group, the diamine component may be only the siloxane bond-containing diamine.

  As the diamine component, in addition to the above-described siloxane bond-containing diamine and diaminocarboxylic acid, another diamine may be further contained. As such a diamine, an aromatic diamine is usually used in order to improve the heat resistance of the polyimide, the adhesion to the electrodeposit, and the degree of polymerization. Examples of such aromatic diamines include m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4′-diamino-3,3′-dimethyl-1,1′-biphenyl, 4, 4'-diamino-3,3'-dihydroxy-1,1'-biphenyl, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,4'-diamino Diphenylsulfone, 4,4′-diaminodiphenyl sulfide, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) ) Benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphe Nyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (3-aminophenoxy) Phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,6-diaminopyridine, 2,6-diamino-4-methylpyridine, 4,4 ′-(9-fluorenylidene) dianiline, α, α-bis (4-aminophenyl) -1,3-diisopropylbenzene can be mentioned, among which bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] Sulfone is more preferred.

  In the total diamine component, the proportion of the siloxane bond-containing diamine is preferably 5 to 90 mol%, more preferably 15 to 50 mol%. When the siloxane bond-containing diamine unit is less than 5 mol%, the electrodeposition coating film of polyimide is inferior in elongation, and it becomes difficult to obtain sufficient flexibility, and peeling and cracking are liable to occur. Further, the ratio of the aromatic diaminocarboxylic acid or a salt thereof is preferably 10 to 70 mol% (however, the total of the siloxane bond-containing diamine and the aromatic diaminocarboxylic acid or a salt thereof is 100 mol% or less, Moreover, the 3rd diamine component may be included as above-mentioned.

  On the other hand, as a tetracarboxylic dianhydride component in polyimide, aromatic tetracarboxylic dianhydride is usually used from the viewpoint of heat resistance of polyimide and compatibility of polysiloxane diamine. For example, pyromellitic dianhydride 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride , Bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride Products, 3,3 ′, 4,4′-biphenylsulfonetetracarboxylic dianhydride, and the like. Among these, heat resistance of polyimide, adhesion to an electrodeposit, polysiloxane di From the viewpoints of amine compatibility and polymerization rate, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 3,3 ′, 4, Particularly preferred are 4′-benzophenone tetracarboxylic dianhydride and 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride. These exemplary tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  In the present invention, a block copolymerized polyimide having a siloxane bond (—Si—O—) in the molecular skeleton (that is, the main chain of polyimide) and an anionic group in the molecule is produced by applying a known method. can do. That is, it can be performed according to a known method for producing a block copolymerized polyimide (for example, the methods described in Patent Documents 9 and 10).

  A water-soluble polar solvent is used for the polymerization reaction. Specifically, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP) , Γ-butyrolactone (γBL), anisole, tetramethylurea, and sulfolane, and NMP is preferable. In such a water-soluble polar solvent, tetracarboxylic dianhydride and diamine are added in an approximately equimolar amount (preferably in a molar ratio of 1: 0.95 to 1.05) and heated in the presence of a catalyst to perform a dehydration imidization reaction. To produce a polyimide solution directly. The catalyst is a two-component composite catalyst composed of a lactone and a base or a crotonic acid and a base. The lactone is preferably γ-valerolactone, and the base is preferably pyridine or N-methylmorpholine. The mixing ratio of lactone or crotonic acid and base (lactone or crotonic acid: base) is 1: 1 to 5 (molar equivalent), preferably 1: 1 to 2. In the presence of water, it acts as an acid-base double salt, exhibits catalytic action, completes imidization, and water comes out of the reaction system (preferably, polycondensation reaction is performed in the presence of toluene, and When it is removed from the reaction system together with toluene, the catalytic action is lost. The amount of the catalyst used is usually 0.01 to 0.2 mol, preferably 0.02 to 0.1 mol, per 1 mol of tetracarboxylic dianhydride. As described above, the mixing ratio of tetracarboxylic dianhydride and diamine (tetracarboxylic dianhydride: diamine) used for the imidization reaction is preferably about 1: 1.05 to 0.95 in terms of molar ratio. The concentration of the acid dianhydride in the entire reaction mixture at the start of the reaction is preferably about 4 to 16% by weight, the concentration of lactone or crotonic acid is preferably about 0.2 to 0.6% by weight, and the concentration of the base Is preferably about 0.3 to 0.9% by weight, and the concentration of toluene is preferably about 6 to 15% by weight. The reaction temperature is preferably 150 ° C to 220 ° C. Moreover, reaction time is not specifically limited, Although it changes with the molecular weight etc. of the polyimide which is going to manufacture, it is about 180 to 900 minutes normally. Moreover, it is preferable to perform reaction under stirring.

  In a water-soluble polar solvent, an acid dianhydride and a diamine are heated in the presence of the above two-component acid catalyst to form an imide oligomer, and then an acid dianhydride or / and a diamine are added to the second stage. By reacting, a polyimide can be produced. By this method, random copolymerization due to an exchange reaction occurring between amic acids can be prevented. As a result, a block copolymerized polyimide can be produced. The solid concentration at this time is preferably 10 to 40% by weight, more preferably 20 to 30% by weight.

  The block copolymer polyimide preferably has an inherent logarithmic viscosity (25 ° C.) of 5000 to 50000 mPas, more preferably 5000 to 15000 mPas when 20 wt% NMP solution is used.

  Further, the weight average molecular weight (Mw) is preferably 20,000 to 150,000, particularly preferably 45,000 to 90,000 in terms of polystyrene. When the weight average molecular weight of the polyimide is less than 20,000, the heat resistance of the electrodeposition coating film tends to decrease, the coating film surface becomes rough, and the aesthetics and withstand voltage characteristics tend to decrease. Further, when the weight average molecular weight is larger than 150,000, the polyimide resin tends to have water repellency with respect to water.

  Moreover, about a number average molecular weight (Mn), 10,000-70,000 are preferable in polystyrene conversion, More preferably, it is 20,000-40,000. When the number average molecular weight is less than 10,000, the electrodeposition efficiency may be lowered, and the heat resistance and voltage resistance may be lowered.

  The molecular weight is a molecular weight in terms of polystyrene measured by GPC (gel permeation chromatography), and is a value measured by using HLC-8220 manufactured by Tosoh Corporation as a GPC device and SCkgel Super-H-RC as a column. is there.

  In the present invention, the “suspension type paint” means that the block copolymer polyimide has a particle size when the particle size / size distribution of the dispersed particles in the paint is measured by a laser Doppler method (dynamic / electrophoretic light scattering method). Is forming a suspension observed as precipitated particles (solid particles) of 0.05 μm or more. Therefore, even if the block copolymerized polyimide is included, a paint in which the block copolymerized polyimide is not observed as a precipitated particle (solid particle) having a particle size of 0.05 μm or more is included in the “suspension type paint” in the present invention. I can't. The electrodeposition coating composition previously proposed by the present applicant (Patent Document 7) is a homogeneous solution (solution dispersion) and is not included in the “suspension type coating” referred to in the present invention.

  In the suspension type polyimide electrodeposition paint of the present invention (hereinafter also simply referred to as “suspension type electrodeposition paint”), the average particle size of the precipitated particles of the block copolymerized polyimide is preferably 0.05 to 5 μm, 5 μm is more preferable, and 0.5 to 3 μm is particularly preferable. If the average particle size of the precipitated particles is less than 0.05 μm, the electrodeposition efficiency tends to decrease. If the average particle size exceeds 5 μm, the uniformity of the coating film and pinholes may occur.

  The suspension-type electrodeposition paint of the present invention has a feature that the variation in the particle size of the precipitated particles of the block copolymerized polyimide is extremely small. That is, assuming that the average particle size of the precipitated particles of the block copolymerized polyimide is D1, all particles having a particle size falling within a particle size range of (D1-0.3 × D1) μm to (D1 + 0.3 × D1) μm Has a sharp particle size distribution of 55% (number basis) or more (preferably 60% (number basis) or more, more preferably 70% (number basis) or more, particularly preferably 80% (number basis) or more). .

  The particle size of the precipitated particles of the block copolymerized polyimide in the suspension type electrodeposition paint of the present invention is measured by a laser Doppler method (dynamic / electrophoretic light scattering method), and the particle size is measured as a spherical equivalent diameter. The average particle diameter is the number average diameter. As a particle size measuring device by laser Doppler method (dynamic / electrophoretic light scattering method), ELSZ-2 (Zeta potential / particle size measuring device), etc., can be used.

  The suspension-type polyimide electrodeposition coating of the present invention is a suspension in which deposited particles of block copolymerized polyimide having a fine particle size and a very small particle size dispersion as described above are dispersed. It is possible to form an electrodeposition film having extremely high uniformity of properties and extremely small variations in mechanical properties (strength, etc.) and physical properties (voltage resistance, heat resistance, etc.). For this reason, by using the suspension-type polyimide electrodeposition paint of the present invention, it is possible to produce an insulating member (part) having an insulating coating having both extremely high insulating properties (particularly voltage resistance) and heat resistance at a high yield. it can.

The suspension type polyimide electrodeposition paint of the present invention can be produced by the following method.
First, a solution containing a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule (hereinafter also simply referred to as “polyimide solution”) obtained through the above-described polymerization reaction. Heat. The heating temperature here is usually about 100 to 180 ° C, preferably about 120 to 160 ° C. When the heating temperature is less than 100 ° C, the block copolymerized polyimide does not dissolve, and when it exceeds 180 ° C, the polyimide is hydrolyzed and the molecular weight tends to decrease.

  Next, after adding and diluting a water-soluble polar solvent to a polyimide solution as needed, the poor solvent with respect to a block copolymerization polyimide and a basic compound are mixed, and the block copolymerization polyimide is neutralized. In addition, the block copolymerization polyimide solution before adding a poor solvent and a basic compound has the density | concentration of a block copolymerization polyimide normally about 15 to 25 weight%, and electrical conductivity is about 3-6 mS / m.

  The basic compound is not particularly limited as long as it can neutralize the anionic group of the block copolymer polyimide, but a basic nitrogen-containing compound is preferable, for example, N, N-dimethylaminoethanol, triethylamine, and the like. Primary amines such as triethanolamine, N-dimethylbenzylamine and ammonia; secondary amines; tertiary amines and the like. Also, nitrogen-containing five-membered heterocyclic compounds such as pyrrole, imidazole, oxazole, pyrazole, isoxazole, thiazole, isothiazole, and nitrogen-containing six-membered heterocyclic compounds such as pyridine, pyridazine, pyrimidine, pyrazine, piperidine, piperazine, morpholine, etc. A nitrogen-containing heterocyclic compound is mentioned. In addition, since many aliphatic amines have a strong odor, nitrogen-containing heterocyclic compounds are preferred from the viewpoint of low odor. In consideration of the toxicity of the paint, piperidine and morpholine having low toxicity are preferable among the nitrogen-containing heterocyclic compounds. The basic compound is used in such an amount that the acidic group in the polyimide is stably dissolved or dispersed in the aqueous solution, and is usually such an amount that the theoretical neutralization rate is about 70 to 130%.

  In addition, examples of the poor solvent for the block copolymerized polyimide include alcohols or ketones having a phenyl group, a furfuryl group, or a naphthyl group. Specifically, acetophenone, benzyl alcohol, 4-methylbenzyl alcohol, 4- Examples include methoxybenzyl alcohol, ethylene glycol monophenyl ether, phenoxy-2-ethanol, cinnamyl alcohol, furfuryl alcohol, and naphthyl carbinol. In addition, an aliphatic alcohol solvent can be used, and the aliphatic alcohol solvent is preferable in terms of low toxicity, and an aliphatic alcohol solvent having an ether group is particularly preferable. Examples of the aliphatic alcohol solvent include 1-propanol, isopropyl alcohol, ethylene glycols, and propylene glycols. Specific examples of ethylene glycols and propylene glycols include dipropylene glycol, tripropylene glycol, ethylene glycol monoethyl ether, propylene glycol monomethyl ether (1-methoxy-2-propanol), propylene glycol methyl ether acetate, and the like. . These poor solvents can use 1 type (s) or 2 or more types. The blending amount of the poor solvent is determined from the viewpoint of precipitating polyimide into fine particles in the dilution step described later, and is preferably 50 to 300% by weight, more preferably 100 to 200% by weight, based on the solid content of the polyimide solution. It is.

  The mixing order of the basic compound and the poor solvent is not particularly limited, and the basic compound and the poor solvent may be added simultaneously or in the order of the poor solvent and the basic compound. Therefore, the order of adding the poor solvent after adding the basic compound is preferable. In addition, the basic compound and the poor solvent are usually mixed with stirring, and the stirring at this time can be performed with various general types of stirring devices. For example, turbine-type stirrer, colloid mill, homomixer, homogenizer, disper stirrer, line mixer equipped with a movable stirrer, non-movable line-type mixer (static mixer, trade name, manufactured by Noritake Co., Ltd.), High pressure homogenizers, rotation / revolution mixers, and the like can be given. In addition, in order to form a more uniform mixed (dispersed) state, a thin-film swirl stirrer (a rotating shaft is concentrically provided in a cylindrical stirring tank, and a rotary blade slightly smaller in diameter than the stirring tank is attached to the rotating shaft. In addition, a stirrer of a type in which the liquid to be treated is stirred on the inner surface of the stirring tank while being spread in a thin film cylindrical shape by high-speed rotation of the rotary blades may be used.

  Next, the solution of the block copolymerized polyimide thus neutralized is allowed to stand at room temperature until the amount of change in electrical conductivity per day of the solution becomes 0.1 mS / m or less. That is, if the neutralized block copolymer polyimide solution is allowed to stand at room temperature, the compatibility between the blending components is improved and the electrical conductivity of the solution is lowered, but the uniformity of the solution is increased. If the amount of decrease in electrical conductivity per day is reduced and the amount of change in electrical conductivity per day is reduced to 0.1 mS / m or less, the block copolymerized polyimide is finely divided in the dilution step by water injection described later. Thus, the coating can be deposited as solid particles having a small variation in particle size, and an electrodeposition coating with high uniformity in thickness can be obtained. If the diluting step by adding water, which will be described later, is performed before the amount of decrease in the electric conductivity per day of the neutralized block copolymer polyimide solution becomes 0.1 mS / m or less, the block copolymer polyimide is used. Is difficult to precipitate as solid particles having the aforementioned average particle diameter and having a sharp particle size distribution. For this reason, even if it has the above-mentioned average particle diameter, since the dispersion | variation in a particle diameter is large, the obtained electrodeposition film will become a thing with a large dispersion in thickness. Here, standing at room temperature refers to placing a neutralized block copolymerized polyimide solution in an environment where the temperature is 20 to 25 ° C. and the humidity is 30 to 80% RH. The electric conductivity of the solution of the block copolymerized polyimide that is allowed to stand until the amount of decrease in the degree becomes 0.1 mS / m or less is about 1.7 to 2.7 mS / m. In addition, the measuring method of the electrical conductivity of a solution is not specifically limited, For example, it can carry out with the general measuring apparatus using the alternating current 2 electrode method.

  Next, to the block copolymerized polyimide solution that was allowed to stand until the amount of decrease in the electrical conductivity per day becomes 0.1 mS / m or less, water was added with stirring to block the block copolymerized polyimide. A suspension type paint is prepared by precipitation. In this case, the total amount of water is such that the final solid content concentration of the paint is 1 to 12% by weight.

  The introduction of water is a first dilution step in which an amount of water smaller than the amount capable of depositing the block copolymerized polyimide is added under stirring, and after the first dilution step, water is further added under stirring, This is performed separately from the second dilution step in which the block copolymerized polyimide is precipitated. The amount of water on which the block copolymerized polyimide can precipitate can be known by conducting preliminary experiments several times in advance.

  The reason why the first diluting step and the second diluting step are divided is to cause precipitation of the block copolymerized polyimide after the solution just before the block copolymerized polyimide is made to be in a more uniform dispersed state. The block copolymer polyimide is precipitated as solid particles having a sufficiently small particle size by making the solution just before the block copolymer polyimide precipitates into a more uniform dispersed state and then causing the precipitation of the block copolymer polyimide. In addition, the dispersion stability of the dispersion containing the solid particles of the block copolymerized polyimide thus precipitated is improved. When the amount of water corresponding to the final solid content concentration of the paint is added all at once, the block copolymerized polyimide does not precipitate or the particle size of the deposited block copolymerized polyimide particles increases, and the particle size also varies. It gets bigger. Moreover, the storage stability of the electrodeposition paint finally obtained will also fall. In addition, the block copolymerized polyimide particles are deposited because the polyimide cannot be precipitated while maintaining a highly uniform dispersion state even when water in an amount corresponding to the final solid content concentration of the paint is continuously added. As a result, the particle size of the particles increases and the variation in particle size also increases.

  Further, in the second dilution step, it is preferable to add water in at least two times or more. This is because the polyimide can be precipitated while maintaining a uniform dispersion of water by adding water in small portions in several batches, and as a result, the block copolymerized polyimide can be precipitated into finer particles. It is because it can do. Thus, by adding water at least twice, the block copolymer polyimide has the above average particle size of 0.05 to 5 μm (preferably 0.1 to 5 μm, more preferably 0.5). ˜3 μm) and the average particle size is D1 (μm), and the particle size falls within the range of (D1−0.3 × D1) μm to (D1 + 0.3 × D1) μm. Suspensions precipitated as particles with a sharp particle size distribution satisfying the relationship of 55% (number basis) or more (preferably 70% (number basis) or more, more preferably 80% (number basis) or more). Can be definitely obtained.

  Although it depends on the amount of water introduced once and the stirring ability of the stirrer, the water introduction period (that is, the interval between the introduction of water and the introduction of the next water) is approximately 0.25 hours. It is preferable to leave more than 0.5 hours, preferably 0.5 hours or more. A more uniform dispersion state can be formed by sufficiently freeing the water injection period. It should be noted that, if the water input period is made longer than necessary, the effect of improving the dispersion state reaches its peak, and the decrease in efficiency becomes remarkable. Therefore, the water input period is preferably 2 hours or less. In addition, since the dispersion capacity by the stirrer can be controlled uniformly, it is preferable that the amount of water input at each input to be added in multiple times is not greatly changed, and the maximum input amount between the multiple inputs is the minimum input amount. The amount is preferably 5 times or less, and it is more preferable that the amount of each input between a plurality of inputs is substantially the same.

  Even in the first dilution step, in order to form a more uniformly dispersed state of water, it is preferable to add water in small portions in multiple times. It is preferable that the amount of water used at the time is approximately equal.

  Stirring in the first and second dilution steps is preferably performed with a stirrer capable of sufficiently dispersing a small amount of water in a short time, and a thin-film swirl stirrer (with a rotating shaft concentrically in a cylindrical stirring tank). A stirrer of a type in which a rotating blade having a diameter slightly smaller than that of a stirring tank is attached to the rotating shaft, and the liquid to be treated is stirred on the inner surface of the stirring tank while being spread in a thin-film cylindrical shape by the rotation of the rotating blade). The

  Here, the thin-film swirl type stirrer has a turbine of the same shape as the container in an in-line container, and a centrifugal force in the container direction is generated when the turbine rotates at high speed, so that the solution in the container is fixed to the inner wall of the container. Further, the liquid phase and the solid phase are dispersed between the container and the turbine by centrifugal force and shear stress due to high-speed rotation. In the dispersion of water in the block copolymerized polyimide solution (polyimide varnish) in the present invention, the polyimide is deposited by the polyimide varnish coming into contact with water. At that time, if the shear shear stress is not sufficient, the polyimide particles and water tend to separate and precipitate. If the centrifugal force is not sufficient, the solution accumulates in the lower part of the container, and the polyimide solidifies in a lump by contact between water and the polyimide. Therefore, in the production of the suspension type polyimide electrodeposition paint of the present invention using a thin film swirl type stirrer, the centrifugal force and the inner diameter of the container which can fix the block copolymerized polyimide solution (polyimide varnish) to the inner wall of the container are calculated. And stirring is performed. Further, in order to prevent the polyimide from being decomposed by heat generated due to centrifugal force and shear stress, the rotational speed of the turbine is determined so that the temperature in the container is equal to or lower than the decomposition temperature.

  Stirring conditions in the thin-film swirl stirrer are not particularly limited, but the rotational speed of the rotating shaft of the turbine is preferably 8000 to 12000 rpm, and the peripheral speed is preferably 30 to 50 m / s. Moreover, the temperature of the solution at the time of stirring is preferably 80 ° C. or less, and more preferably 60 ° C. or less, from the viewpoint of preventing changes in solvent composition and resin deterioration. In addition, 45 degreeC or more is preferable from a viewpoint of controlling precipitation of resin gently, and a viewpoint of lowering | hanging solution viscosity and raising stirring efficiency.

  After the second dilution step, an appropriate amount of a water-soluble polar solvent may be added for the purpose of adjusting the viscosity and electrical conductivity of the final paint. Here, specific examples of the water-soluble polar solvent include the same water-soluble polar solvents used for the polymerization reaction of the block copolymerized polyimide.

  The solid content concentration of the suspension-type polyimide electrodeposition coating composition of the present invention is preferably 1 to 12% by weight, more preferably 2 to 9% by weight.

  The suspension-type polyimide electrodeposition coating of the present invention produced in this way maintains a good dispersion state without causing aggregation, solid-liquid separation, etc. of the solid particles of the block copolymerized polyimide even after long-term storage. Therefore, it can cope with mass production of insulating members (components). Further, the film has high electrical conductivity during the growth process, and a polyimide film having high uniformity in film properties can be formed on the outer peripheral surface of the member (electrodeposit) even under low current electrodeposition conditions.

  The electrodeposition coating method of the electrodeposition paint according to the present invention comprises immersing a member (electrodeposit) in the electrodeposition paint, and using the member (electrodeposit) as an anode, a polyimide coating on the member (electrodeposit) through an electric current. Can be grown.

  Electrodeposition can be performed by the constant current method or the constant voltage method. For example, in the case of the constant current method, the conditions of current value: 1.0 to 200 mA, DC voltage: 5 to 200 V (preferably 30 to 120 V) are used. Can be mentioned. The electrodeposition time varies depending on the electrodeposition conditions, the thickness of the film to be formed, etc., but is generally selected from the range of 10 to 120 seconds, preferably 30 to 60 seconds. Moreover, the composition temperature at the time of electrodeposition is 10-40 degreeC normally, Preferably it is 20-30 degreeC. If the electrodeposition voltage is lower than 5V, it tends to be difficult to form a film by electrodeposition. If the electrodeposition voltage is higher than 200V, the generation of oxygen from the object to be coated becomes intense and a uniform film cannot be formed. If the electrodeposition time is too short, the film does not grow sufficiently even if the electrodeposition voltage is set high, so pinholes are likely to occur, and the withstand voltage performance of the electrodeposition film tends to decrease, exceeding 120 seconds. If the thickness of the coating becomes thicker than necessary, it is not economical. Further, when the composition temperature is lower than 10 ° C., it is difficult to form a film by electrodeposition, and when the temperature is higher than 40 ° C., temperature management is required, which increases the production cost.

  The film formed by electrodeposition is preferably heat-dried (baked). Baking is performed at 70 to 110 ° C. for 10 to 60 minutes in the first stage, then at 160 to 180 ° C. for 10 to 60 minutes in the second stage and further at 200 to 220 ° C. for 30 to 30 minutes. It is preferable to perform a third stage baking process for 60 minutes. By performing such a three-stage baking process, it is possible to form a sufficiently dried polyimide film that adheres to the electrodeposit with high adhesion.

  The polyimide coating obtained by heating and drying (baking) the electrodeposition coating with the electrodeposition coating of the present invention has extremely high coating thickness uniformity and high heat resistance (temperature index evaluation method based on JIS C 3003). At a temperature index of 180 ° C. (heat resistance category: H), preferably 200 ° C. or higher (heat resistance category: C)), and an elongation measured in accordance with JIS C 2151 is 5% or more. It preferably has a high elongation of 8% or more.

  The material of the member (electrodeposit) on which the composition for electrodeposition coating of the present invention is electrodeposited is not particularly limited, but from the viewpoint of conductivity, copper, copper alloy, copper grat aluminum, aluminum, zinc Examples thereof include plated iron, silver, gold, nickel, titanium, tungsten, etc. Among them, silver or copper is preferable. Moreover, even if it is an insulating product, the electrodeposition film | membrane by the composition for electrodeposition coating materials of this invention can be formed if what carried out the electroconductive process like plating on the surface.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
[Synthesis of varnish containing block copolymerized polyimide]
A 2-liter separable three-necked flask equipped with a stainless steel vertical stirrer was equipped with a ball condenser equipped with a water separation trap. The flask was charged with 58.84 g (200 mmol) of 3,3′4,4′-biphenyltetracarboxylic dianhydride, 43.25 g (100 mmol) of bis- [4- (4-aminophenoxy) phenyl] sulfone, γ -After charging 4.0 g (40 mmol) of valerolactone, 6.3 g (80 mmol) of pyridine, 531 g of N-methyl-2-pyrrolidone (NMP) and 50 g of toluene, the mixture was stirred for 10 minutes at 180 rpm in a nitrogen atmosphere at room temperature. The mixture was heated to 180 ° C. and stirred for 2 hours. During the reaction, toluene-water azeotrope was removed. Next, the mixture was cooled to room temperature, 64.45 g (200 mmol) of 3,3′4,4′-benzophenonetetracarboxylic dianhydride, 83.00 g (100 mmol) of KF-8010 manufactured by Shin-Etsu Chemical Co., Ltd., 30.43 g (200 mmol) of 5-diaminobenzoic acid, 531 g of NMP and 50 g of toluene were added and reacted for 8 hours while stirring at 180 ° C. and 180 rpm. By removing the reflux from the system, a polyimide solution having a polyimide content of 20% by weight was obtained. The number average molecular weight and weight average molecular weight of the obtained polyimide were 24,000 and 68,000, respectively.

[Preparation of suspension type paint]
100 g of the above-mentioned polyimide varnish (solid content concentration 20% by weight) was heated at 160 ° C. for 1 hour to melt the polyimide. Next, 35 g of N-methylpyrrolidone and 1.3 g of piperidine were added to the polyimide varnish and stirred, and then 30 g of propylene glycol monomethyl ether was added and stirred until uniform (neutralization rate: 100%). Next, the varnish was transferred to a container, sealed, and stored at room temperature, and allowed to stand until the change in electrical conductivity of the solution per day was 0.1 mS / m or less. The number of days of standing was 4 days. In addition, the electrical conductivity was measured with the measuring apparatus (Horiba Seisakusho make electric conductivity meter DS-12) using the alternating current 2 electrode method. Next, a preliminary experiment was performed, and it was confirmed that the minimum input amount of water from which the polyimide was deposited was 12 g. Next, 55 g of water was added in three portions (10 g, 15 g, 30 g) while stirring at a rotation speed of 10,000 rpm in the stirring section using a thin-film swirl type stirrer. The interval between the first charging and the second charging is 0.5 hours, the interval between the second charging and the third charging is 1 hour, and the mixture is stirred for 1.5 hours after the third charging. An electrodeposition solution was prepared. The electric conductivity of the electrodeposition liquid was 3.9 mS / m, the pH was 7.11, and the average particle diameter (D1) of the dispersed particles in the electrodeposition liquid was 1.1 μm. In addition, particles in a particle size range of ± 30% of the average particle size (that is, a particle size range of (D1−0.3 × D1) μm to (D1 + 0.3 × D1) μm) are 75% (number of particles). Standard).

(Comparative Example 1)
In the preparation of the suspension-type paint, the varnish after the neutralization treatment was not stored, and the varnish after the neutralization treatment (electric conductivity 4.5 mS / m) was immediately subjected to the water addition treatment as in Example 1. An electrodeposition solution was prepared in the same manner. The electrodeposition solution had an electric conductivity of 5.8 mS / m and a pH of 7.5. No precipitated particles (dispersed particles) were observed in the electrodeposition solution.

(Comparative Example 2)
In the preparation of the suspension-type paint, an electrodeposition solution was prepared in the same manner as in Example 1 except that the storage time of the varnish after the neutralization treatment was set to 2 days. The change in the electric conductivity per day on the second day of the solution was 0.8 mS / m, the electric conductivity of the final electrodeposition solution was 5.0 mS / m, and the pH was 7.2. The average particle diameter (D1) of the dispersed particles in the obtained electrodeposition liquid is 0.3 μm, and a particle diameter range of ± 30% of the average particle diameter (D1) (that is, (D1−0.3 × D1) μm). (D1 + 0.3 × D1) μm particle size range) was 45% (number basis) of the total.

(Comparative Example 3)
An electrodeposition solution was prepared in the same manner as in Example 1 except that 55 g of water was added at a time and stirred for 2 hours in the preparation of the suspension type paint. The electrodeposition solution had an electric conductivity of 4.5 mS / m and a pH of 7.1. The average particle diameter (D1) of the dispersed particles in the obtained electrodeposition liquid is 5.5 μm, and a particle diameter range of ± 30% of the average particle diameter (D1) (that is, (D1-0.3 × D1) μm Particles in the range of (D1 + 0.3 × D1) μm in particle size range) accounted for 20% of the total (number basis).

(Comparative Example 4)
An electrodeposition solution was prepared in the same manner as in Example 1 except that TK homomixer MARKII (stirring condition: rotation speed: 10,000 rpm) was used as a stirring device in the water charging process (dilution process). The electrodeposition solution had an electric conductivity of 3.9 mS / m and a pH of 7.2. The average particle diameter (D1) of the dispersed particles in the obtained electrodeposition liquid is 1.2 μm, and a particle diameter range of ± 30% of the average particle diameter (D1) (that is, (D1-0.3 × D1) μm The particle size in the range of (D1 + 0.3 × D1) μm particle size range) was 40% of the total (based on the number).

(Comparative Example 5)
The polyimide varnish having a solid content concentration of 20.0% by weight obtained in Example 1 was stirred at 160 ° C. for 1 hour in a nitrogen atmosphere, and then rapidly cooled to 30 ° C., 41.9 g of N-methylpyrrolidone and piperidine 2. 2 g (neutralization rate 200%) was added and stirred vigorously. Thereafter, the mixture was stirred while adding 124 g of propylene glycol monomethyl ether, and 49 g of water was added dropwise to prepare an electrodeposition solution. The electrodeposition liquid was a cloudy liquid having a solid content concentration of 6.0%, pH 8.2, and electric conductivity of 7.1 mS / m. Further, the average particle diameter (D1) of the dispersed particles in the electrodeposition liquid is 0.7 μm, and a particle diameter range of ± 30% of the average particle diameter (that is, (D1−0.3 × D1) μm to (D1 + 0.3). × D1) Particles in the μm particle size range) were 50% of the total (based on the number).

(Example 2)
An electrodeposition solution was prepared in the same manner as in Example 1 except that the amount of piperidine added was 1.7 g (neutralization rate 130%). The electrodeposition solution had an electric conductivity of 4.1 mS / m and a pH of 7.3. The average particle diameter (D1) of the dispersed particles in the obtained electrodeposition liquid is 0.6 μm, and a particle diameter range of ± 30% of the average particle diameter (D1) (that is, (D1-0.3 × D1) μm Particles in the range of (D1 + 0.3 × D1) μm in particle size range) accounted for 80% of the total (number basis).

(Example 3)
An electrodeposition solution was prepared in the same manner as in Example 1 except that the amount of piperidine added was 1.1 g (neutralization rate 80%). The electrodeposition solution had an electrical conductivity of 3.6 mS / m and a pH of 7.1. The average particle diameter (D1) of the dispersed particles in the obtained electrodeposition liquid is 1.7 μm, and a particle diameter range of ± 30% of the average particle diameter (D1) (that is, (D1-0.3 × D1) μm The particle size in the range of ~ (D1 + 0.3 × D1) μm) was 60% of the total (number basis).

(Example 4)
55 g of water was added in 4 batches (10 g, 15 g, 15 g, 15 g) (the interval between the first and second injections was 0.5 hours, the interval between the second and third injections, and A cloudy and light brown electrodeposition solution was prepared in the same manner as in Example 1 except that the interval between the third injection and the fourth injection was 1 hour, and the mixture was stirred for 1 hour after the fourth injection. The electric conductivity of the electrodeposition liquid was 3.9 mS / m, the pH was 7.2, and the average particle diameter (D1) of the dispersed particles in the electrodeposition liquid was 0.8 μm. Further, the particles in the particle size range of ± 30% of the average particle size (that is, the particle size range of (D1−0.3 × D1) μm to (D1 + 0.3 × D1) μm) is 70% of the total number (number Standard).

(Example 5)
In the preparation of the suspension-type paint, an electrodeposition solution was prepared in the same manner as in Example 1 except that the storage time of the varnish after the neutralization treatment was set to 10 days. The change of the electric conductivity per day on the 10th day of the solution was 0.05 mS / m, the electric conductivity of the final electrodeposition solution was 3.7 mS / m, and the pH was 7.2. The average particle diameter (D1) of the dispersed particles in the obtained electrodeposition liquid is 1.4 μm, and the particle diameter range of ± 30% of the average particle diameter (D1) (ie, D1-0.3 × D1) μm to Particles in (D1 + 0.3 × D1) μm particle size range) accounted for 75% of the total (based on the number).

  The performance (electrodeposition rate, uniformity of electrodeposition coating thickness) and storage stability of the electrodeposition solutions obtained in the above Examples and Comparative Examples were evaluated.

[Electrodeposition speed]
Using a coulomb meter on a copper wire 20 cm in diameter of 1 mm, the amount of coulomb was adjusted so that the film thickness was 20 μm, the time when electrodeposition was performed at 30 V (maximum current value 200 mA) was measured and evaluated according to the following criteria.
Within 5 seconds: Good (○)
Over 5 seconds and within 10 seconds: Allowable (△)
Over 10 seconds: Impossible (×)

[Uniformity of electrodeposition film thickness]
Insulation coating obtained by drying the electrodeposition coating of the sample after the electrodeposition rate measurement test (drying at 90 ° C./30 minutes, 180 ° C./30 minutes, 220 ° C./30 minutes with a hot air dryer) Measure the outer diameter of the copper wire, measure (outside diameter-conductor diameter) ÷ 2 as the film thickness, measure 8 locations of the sample (8 locations separated at equal intervals of 2 cm in the axial direction of the copper wire), Variation was judged from the minimum film thickness. Evaluation was made according to the following criteria based on the difference between the maximum film thickness and the minimum film thickness.
3 μm or less: Good (◯)
Over 3μm and below 5μm: Permissible (△)
Over 5 μm: Impossible (×)

[Storage stability of paint]
The solid content concentration of the supernatant of the electrodeposition solution after standing at room temperature for 3 months was measured, and the amount of decrease from the solid content concentration before standing was evaluated as the amount of precipitation.
When the sediment was not observed or was slight, it was judged as good (◯), and when there was much sediment or gelation was found, it was judged as poor (×). Note that “there is a lot of sediment” means that the reduction rate of the solid content in the supernatant is 35% by weight or more.

Claims (19)

A suspension-type polyimide electrodeposition coating material in which particles of a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule are dispersed,
The block copolymer polyimide particles measured by laser Doppler method (dynamic / electrophoretic light scattering method) have an average particle diameter of 0.05 to 5 μm and the average particle diameter is D1 (μm). , (D1−0.3 × D1) μm to (D1 + 0.3 × D1) μm, and the particle size distribution falls within 55% (number basis) of the total particle size. Suspension type polyimide electrodeposition paint.   The suspension-type polyimide electrodeposition coating composition according to claim 1, wherein the block copolymerized polyimide contains a diamine having a siloxane bond in the molecular skeleton as one of the diamine components. Diamines having a siloxane bond in the molecular skeleton are bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane, and the following general The suspension type polyimide electrodeposition paint according to claim 1 or 2, which is one or more selected from the group consisting of compounds represented by formula (I).

(In the formula, each of four R's independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxy groups, and l and m each represent Independently represents an integer of 1 to 4, and n represents an integer of 1 to 20.)   The suspension-type polyimide electrodeposition paint according to any one of claims 1 to 3, wherein the block copolymerized polyimide contains an aromatic diaminocarboxylic acid as one of the diamine components.   The suspension type polyimide electrodeposition coating composition according to any one of claims 1 to 4, wherein the anionic group of the block copolymerized polyimide is a carboxylic acid group or a salt thereof, and / or a sulfonic acid group or a salt thereof.   In the total diamine component of the block copolymerized polyimide, the proportion of the diamine having a siloxane bond in the molecular skeleton is 5 to 90 mol%, and the proportion of the aromatic diaminocarboxylic acid is 10 to 70 mol% (however, the total of both is 100 The suspension type polyimide electrodeposition coating composition according to any one of claims 3 to 5, which is not more than mol% and may contain a third diamine component.   The insulating member which has an electrodeposition film by the electrodeposition coating material of any one of Claims 1-6 as an insulating layer. A method for producing a suspension-type polyimide electrodeposition coating material in which particles of a block copolymerized polyimide having a siloxane bond in a molecular skeleton and an anionic group in a molecule are dispersed,
In a polyimide solution having a siloxane bond in the molecular skeleton and a block copolymerized polyimide having an anionic group in the molecule dissolved in a water-soluble polar solvent, the concentration of the block copolymerized polyimide is 15 to 25% by weight. After blending a poor solvent and a basic compound for the block copolymerized polyimide and neutralizing the block copolymerized polyimide, the amount of change in electrical conductivity per day of the polyimide solution at room temperature is 0.1 mS / leaving the solution until it is less than or equal to m,
A first dilution step in which an amount of water smaller than the amount of the block copolymerized polyimide that can be deposited in the polyimide solution after being left standing is added under stirring;
After the first dilution step, the second dilution step of adding water with stirring to precipitate the block copolymer polyimide,
A method for producing a suspension-type polyimide electrodeposition paint, comprising using a thin-film swirl stirrer as stirring means in the first and second dilution steps.   9. The method according to claim 8, wherein in the second dilution step, water is added in at least two times.   The compounding amount of the poor solvent is 50 to 300% by weight with respect to the polyimide in the polyimide solution, the compounding amount of the basic compound is an amount such that the polyimide neutralization rate is 70 to 130%, and the total amount of water input The method according to claim 8 or 9, wherein the solid content concentration of the coating is 1 to 12% by weight.   Water-soluble polar solvents include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), γ-butyrolactone (γBL), anisole, tetra The method according to any one of claims 8 to 10, comprising one or more selected from methylurea and sulfolane.   The method according to any one of claims 8 to 11, wherein the poor solvent of the block copolymerized polyimide is an alkoxy-substituted aliphatic alcohol.   The method according to any one of claims 8 to 12, wherein the basic compound is a basic nitrogen-containing compound.   The method according to claim 13, wherein the basic nitrogen-containing compound is a nitrogen-containing heterocyclic compound.   The method according to any one of claims 8 to 14, wherein the block copolymerized polyimide contains a diamine having a siloxane bond in the molecular skeleton as one of the diamine components. Diamines having a siloxane bond in the molecular skeleton are bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane, and the following general The method of Claim 15 which is 1 type (s) or 2 or more types chosen from the group which consists of a compound represented by Formula (I).

(Wherein, four R's independently represent an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxy groups, and l and m are each independently And represents an integer of 1 to 4, and n represents an integer of 1 to 20.)   The method according to any one of claims 8 to 16, wherein the block copolymerized polyimide contains an aromatic diaminocarboxylic acid as one of the diamine components.   The method according to any one of claims 8 to 17, wherein the anionic group of the block copolymerized polyimide is a carboxylic acid group or a salt thereof, and / or a sulfonic acid group or a salt thereof.   In the total diamine component of the block copolymerized polyimide, the proportion of diamine having a siloxane bond in the molecular skeleton is 5 to 90 mol%, and the proportion of aromatic diaminocarboxylic acid is 10 to 70 mol% (however, the total of both is 100 mol) The method according to any one of claims 8 to 17, which is not more than% and may contain a third diamine component.