JP2010106340A - Method for manufacturing insulating member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an insulating member in a high yield, which is insulation-treated with an electrodeposition coating film that has highly uniform film properties, is superior in adhesiveness to a member to be insulation-treated, and further has a high level of voltage resistance and heat resistance. <P>SOLUTION: The method for manufacturing the insulating member includes: an anionic electrodeposition step of immersing the member to be insulation-treated into a suspension-type electrodeposition paint composition which contains a block copolymerization polyimide having a siloxane bond in a molecule skeleton and an anionic group in a molecule, as a resin component, and passing an electric current to the member which has been set as an anode to grow a polyimide coating film on the surface of the member; a step of cleaning the member to be insulation-treated having the polyimide coating film thereon in a cleaning liquid containing a water-soluble polar solvent and water and/or a solvent of an aliphatic alcohol; a step of removing the cleaning liquid by jetting air to the member to be insulation-treated having the polyimide coating film thereon; and a step of drying the polyimide coating film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an insulating member, and more particularly to a method for manufacturing an insulating member that is insulated with an electrodeposition coating made of a specific block copolymerized polyimide.

  Conventionally, as a method for performing an insulation treatment on a member (component) that requires insulation protection, for example, electrodeposition of an electrodeposition paint on the surface of the member to form an insulating layer by an electrodeposition coating is known. As this type of electrodeposition coating, for example, an aqueous dispersion electrodeposition liquid in which a poor solvent and water are added to an organic polar solvent in which a polyamic acid that is a polyimide precursor is dissolved is known. An electrodeposited film is heated to 240 to 260 ° C. and imidized to form an insulating layer (insulating film) (Patent Documents 1 to 3). However, the conventionally proposed electrodeposition coating with an electrodeposition coating cannot always satisfy the difficulty of peeling of the coating or cracking of the coating on the electrodeposition-insulated member. Moreover, it cannot be said that the withstand voltage and heat resistance of the coating are sufficiently high. Therefore, Patent Document 4 discloses a siloxane bond in the main chain as an electrodeposition paint that can improve such a problem of the conventional electrodeposition paint and can form an electrodeposition film that is unlikely to be peeled off or cracked on the electrodeposition. An electrodeposition coating composition containing a specific block copolymerized polyimide having a resin component has been proposed. Compared to conventional polyimide electrodeposition paints, this electrodeposition paint composition is less prone to electrodeposition film peeling and electrodeposition film cracking on electrodeposits (insulation-treated members), and also has heat resistance and voltage resistance. It is possible to form an electrodeposition film having excellent properties.

However, recently, for example, in the fields of electrical / electronic components, automobiles, aerospace, etc., further improvement in heat resistance and voltage resistance of insulating coatings (insulating layers) in insulating members is desired. However, the inventors' research has shown that even the electrodeposition coating composition proposed in Patent Document 4 cannot sufficiently meet such a requirement. That is, since the electrodeposition coating composition proposed in Patent Document 4 consists of a mixed system of several kinds of solvents, the behavior as an electrodeposition coating changes greatly due to a slight change in the blending ratio of the solvent, and the resulting electrodeposition coating is obtained. It was found that the film properties of the film were difficult to be uniform, and as a result, it was impossible to form a highly voltage-resistant or heat-resistant electrodeposition film. In addition, when forming a relatively thin film having a thickness of approximately 15 μm or less, it is found that the withstand voltage varies greatly even if the film has the same film thickness, and an insulating film having a desired characteristic cannot be formed with good reproducibility. It was.
Japanese Patent Laid-Open No. 49-52252 JP 52-32943 A JP-A-63-1111199 Japanese Patent Laid-Open No. 2005-162954 International Publication No. WO99 / 19771 US Pat. No. 5,502,143

  In view of the above circumstances, the problem to be solved by the present invention is that the film property is highly uniform, has excellent adhesion to the member to be insulated, and is insulated by an electrodeposition coating having high voltage resistance and heat resistance. An object of the present invention is to provide a method for producing an insulating member, which can produce a treated insulating member with good reproducibility.

  As a result of intensive studies to solve the above problems, the inventors of the present application have found that a solvent composition used in combination with a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule, and at the time of coating. By devising the temperature conditions, etc., a suspension-type paint in which the block copolymerized polyimide is dispersed as precipitated particles having a relatively large particle size is obtained. Highly uniform electrodeposition coating of uniform thickness can be formed, its voltage resistance and heat resistance are extremely good, and it is possible to form an electrodeposition coating that has been thickened to a level that was difficult in the past, After the electrodeposition film formed after the electrodeposition process is cleaned with a cleaning liquid of a specific composition and the cleaning liquid is removed by spraying air, the film is dried. It was found that further homogenization can be achieved in the film properties, by advancing a further study on the basis of the look 該知, and have completed the present invention.

That is, the present invention is as follows.
(1) A member to be insulated is immersed in a suspension-type electrodeposition coating composition containing a block copolymer polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule as a resin component, An anionic electrodeposition step of growing a polyimide film on the surface of the member through an electric current using the member as an anode;
Cleaning the insulating member having the polyimide coating with a cleaning liquid containing a water-soluble polar solvent and water and / or an aliphatic alcohol solvent;
A step of spraying air on the member to be insulated having the polyimide coating to remove the cleaning liquid;
And a step of drying the polyimide coating.
(2) The method for producing an insulating member according to the above (1), wherein the cleaning liquid contains 50 to 80% by weight of a water-soluble polar solvent and 20 to 50% by weight of water and / or an aliphatic alcohol solvent.
(3) 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 for producing an insulating member according to (2), wherein the insulating member is one or more selected from anisole, tetramethylurea and sulfolane.
(4) The method for producing an insulating member according to any one of (1) to (3), wherein the block copolymerized polyimide is a polyimide containing a diamine having a siloxane bond in the molecular skeleton as one of the diamine components. .
(5) 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 manufacturing method of the insulating member of the said (4) description which is 1 type (s) or 2 or more types chosen from the group which consists of a compound represented with the following general formula (I).

(In the formula, four R's each independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxyl 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.)
(6) Four R in the general formula (I) are each independently an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, a phenyl group, or 1 to 3 carbon atoms. The manufacturing method of the insulating member of the said (5) description showing the phenyl group substituted by the C1-C6 alkyl group or the C1-C6 alkoxyl group.
(7) The anionic group in the molecule of the block copolymerized polyimide is a carboxylic acid group or a salt thereof, and / or a sulfonic acid group or a salt thereof, according to any one of (1) to (6) above. Manufacturing method of the insulating member.
(8) The method for producing an insulating member according to any one of (1) to (7), wherein the block copolymerized polyimide contains an aromatic diaminocarboxylic acid as one of the diamine components.
(9) 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, both Of the insulating member according to (8) above, which may contain a third diamine component).
(10) The method for manufacturing an insulating member according to any one of (1) to (9), wherein the insulating member is an insulated wire and the member to be insulated is a conductor wire.
(11) The method for manufacturing an insulating member according to any one of (1) to (9), wherein the insulating member is an electronic component with an insulating treatment lead terminal, and the insulated member is an electronic component with a lead terminal.

  According to the present invention, it is possible to produce an insulating member that has excellent film quality uniformity, is less likely to be peeled off or cracked against the member to be insulated, and is insulated with an electrodeposition coating that has unprecedented high voltage resistance and heat resistance. Moreover, since the correlation between the thickness of the electrodeposition coating and the withstand voltage is high, an insulating member having a desired withstand voltage can be manufactured with good reproducibility. Therefore, it is possible to manufacture an insulating member having excellent insulation performance and heat resistance, which has not been conventionally obtained, with a high yield.

Hereinafter, the present invention will be described with reference to preferred embodiments.
The term “insulating member” as used in the present invention means a member obtained by forming an insulating layer with an electrodeposition coating on the surface of a member that requires insulation protection on the surface in various technical fields. Insulated wires with an insulating layer formed by an electrodeposition coating on the outer periphery of a conductor wire, an insulating metal having an insulating layer formed by an electrodeposition coating on the outer periphery of a stamped metal plate used in a coil for a laminated transformer Insulating metal plate, lead with an insulating layer formed by electrodeposition coating on the outer periphery of a three-dimensionally formed metal plate by cutting or laminating used for plates, needle guards for measuring probe guards, motor cores, etc. Examples thereof include an electronic component with an insulating treatment lead terminal in which an insulating layer made of an electrodeposition coating is formed on the surface of the lead terminal of the electronic component having the terminal.

  The electrodeposition coating composition used in the present invention is a resin comprising a block copolymerized polyimide having a siloxane bond (—Si—O—) in the molecular skeleton (namely, the main chain of polyimide) and an anionic group in the molecule. Contains as a component.

  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, by adding a different tetracarboxylic dianhydride or / and a diamine different from the above diamine to react (second stage reaction), random copolymerization caused by exchange reaction occurring between amic acids can be prevented. 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 may be a siloxane bond derived from a tetracarboxylic dianhydride component. A siloxane bond derived from a diamine component may be used, but a siloxane bond derived from a diamine component is preferable. Usually, at least a part of the diamine component has a siloxane bond (—Si—O—) in the molecular skeleton. A block copolymerized polyimide obtained using a diamine compound (hereinafter sometimes referred to as “siloxane bond-containing diamine”) is used.

  The siloxane bond-containing diamine can be used without particular limitation as long as it can be imidized with tetracarboxylic dianhydride. For example, bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4 -Aminophenoxy) -1,1,3,3-tetramethyldisiloxane and the 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 alkoxyl 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 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 alkoxyl groups, 1 to 3 alkyl groups or alkoxyl groups may be the same or different when they are 2 or 3 May be. Moreover, as for an alkyl group and an alkoxyl 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 4 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 electrodeposition coating composition used 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), X-22-161A (bis (γ-aminopropyl) polydimethylsiloxane: Shin-Etsu Chemical Co., Ltd .: Amino group equivalent of about 840) and the like, and these are particularly preferable.

  In the electrodeposition coating composition used in the present invention, the anionic group is a group that becomes an anion in a solvent (described later) of the electrodeposition composition, preferably a carboxyl group or a salt thereof, and / or a sulfonic acid. A 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 an electrodeposit (insulation-treated member), 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-naphthalenecarboxylic acid, 1,4-diamino-2-naphthalenecarboxylic acid and the like can be mentioned. As aromatic diaminosulfonic acid, 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) bif 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 film of polyimide is inferior in elongation and it is difficult to obtain sufficient flexibility, and peeling and cracking are likely 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′-biphenylsulfone tetracarboxylic dianhydride, etc. Among these, heat resistance of polyimide, adhesion to electrodeposits, polysiloxane diamine 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 3,3 ′, 4,4 ′ from the viewpoint of compatibility and polymerization rate -Benzophenone tetracarboxylic dianhydride and 3,3 ', 4,4'-biphenylsulfone tetracarboxylic dianhydride are particularly preferred. These exemplified tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The polyimide used as the resin component of the electrodeposition coating composition used in the present invention is soluble in a water-soluble polar solvent (for example, 5% by weight or more in N-methyl-2-pyrrolidone (NMP), preferably Shows solubility at a concentration of 10% by weight or more.) Block copolymerized polyimide. The block copolymerized polyimide and its production method are already known (for example, described in Patent Documents 5 and 6), and the polyimide used in the present invention is also applied to the known method using the diamine component and tetracarboxylic dianhydride. Can be manufactured. 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 this 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 the 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, a polycondensation reaction is performed in the presence of toluene, and water produced is When it is removed from the reaction system together with toluene, the catalytic action is lost. The amount of the catalyst used is usually 1/100 to 1/5 mol, preferably 1/50 to 1/10 mol, relative to tetracarboxylic dianhydride. The mixing ratio (acid / diamine) of tetracarboxylic dianhydride and diamine to be subjected to the imidization reaction is preferably about 1: 0.95 to 1.05 in molar ratio as described above. 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.

  An acid dianhydride and a diamine are heated in a water-soluble polar solvent in the presence of the above-mentioned two-component acid catalyst to form an imide oligomer, and then an acid dianhydride or / and a diamine are added to the second diamine oligomer. A polyimide can be produced by a step reaction. 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 polyimide preferably has an inherent logarithmic viscosity (25 ° C.) of 5000 to 50,000 mPas, more preferably 5000 to 15,000 mPas when 20 wt% NMP solution is used.

  Further, the weight average molecular weight (Mw) of the block copolymerized polyimide used as the resin component 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 electrodeposited coating tends to be reduced, and the coating surface is roughened, and the aesthetics and withstand voltage characteristics tend to be reduced. On the other hand, when the weight average molecular weight is larger than 150,000, the polyimide resin has water repellency with respect to water and easily causes gelation in the electrodeposition liquid (paint) manufacturing process.

  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 tends to decrease, and the heat resistance and voltage resistance may decrease. Here, the molecular weight of the polyimide is a molecular weight in terms of polystyrene measured by GPC, using HLC-8220 (manufactured by Tosoh Corp.) as the GPC device and TSKgel SuperH-RC (manufactured by Tosoh Corp.) as the column. The measured value.

  The electrodeposition coating composition used in the present invention is a suspension type electrodeposition coating. Here, the “suspension type electrodeposition paint” means that the electrodeposition paint composition used in the present invention is a particle size analyzer ELS-Z2 (Otsuka Electronics Co., Ltd.) using an electrophoretic light scattering method (laser Doppler method). The particle diameter of the polyimide particles (precipitated particles) whose measurement results were analyzed by the cumulant analysis method is 0.1 to 10 μm and the standard deviation of the particle diameter is 0.1 to 8 μm. It means that a suspension is formed.

  The electrodeposition coating composition (suspension type electrodeposition coating composition) used in the present invention preferably has an intrinsic relative viscosity of 5 to 100 mPas. A composition having such a viscosity range is suitable as a composition for an electrodeposition coating material that can provide a film thickness of 30 μm or more and a uniform film thickness. The inherent logarithmic viscosity was measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

  Moreover, it is preferable that the average particle diameter of the particle | grains which consist of block copolymerization polyimide is 0.1-10 micrometers, and 0.5-5 micrometers is more preferable. When the average particle size is less than 0.1 μm, the Coulomb efficiency is lowered and the withstand voltage performance is lowered due to overvoltage. On the other hand, if it exceeds 10 μm, the coulombic efficiency is controlled and the leakage current is increased due to the increase in particles, thereby causing a decrease in withstand voltage performance. Therefore, the particle size range in which the control of the coulomb efficiency and the maintenance of the withstand voltage performance are balanced is preferably 0.5 to 5 μm.

  The production of the electrodeposition coating composition (suspension type electrodeposition coating composition) used in the present invention is specifically performed as follows. First, a post-polymerization composition containing a block copolymerized polyimide obtained through the above polymerization reaction (that is, containing a block copolymerized polyimide and a water-soluble polar solvent, and the content of the block copolymerized polyimide is 15 to 25 wt. % Composition) is heated and melted. The heating temperature here is usually about 50 to 180 ° C., preferably about 60 to 160 ° C. When the heating temperature is less than 50 ° C., the block copolymerized polyimide does not dissolve and tends to be difficult to disperse with other solvents. When the heating temperature exceeds 180 ° C., hydrolysis occurs and the molecular weight tends to decrease.

  Next, a basic compound is added to the heated and melted composition and stirred to neutralize the block copolymer polyimide, and then the composition is cooled to 40 ° C. or lower, and the block copolymer polyimide poor solvent and water are further cooled. Is added and mixed and stirred to prepare a suspension.

  In the manufacturing process of such a suspension-type coating composition, when the temperature after cooling of the composition after neutralizing the block copolymerized polyimide exceeds 40 ° C., the polyimide tends to be decomposed by the neutralizing agent. The cooling temperature of the composition is more preferably 30 ° C. or lower. If the cooling temperature of the composition is too low, solidification tends to start again, so the lower limit of the cooling temperature is preferably 20 ° C. or higher.

  The basic compound is not particularly limited as long as it can neutralize the anionic group of the block copolymerized 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 and tertiary amines. 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, morpholine and the like having low toxicity are preferable among the nitrogen-containing heterocyclic compounds. The amount of the basic compound used is such that the acidic group in the polyimide is stably dissolved or dispersed in the aqueous solution, and is usually about 30 to 200 mol% of the theoretical neutralization amount.

  Examples of the poor solvent for the block copolymer 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. An aliphatic alcohol solvent is preferred because of its low toxicity, and an aliphatic alcohol solvent having an ether group is particularly preferred. 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 preferably 10 to 40% by weight and more preferably 10 to 30% by weight with respect to the total amount of the composition. The amount of water is preferably 10 to 30% by weight, more preferably 15 to 30% by weight, based on the total amount of the composition.

  In addition to the poor solvent and water of the block copolymer polyimide, an appropriate amount of a water-soluble polar solvent or an oil-soluble solvent may be added for the purpose of adjusting the viscosity and electrical conductivity of the composition. 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, and examples of the oil-soluble solvent include γ-butyrolactone. In addition, when adding an oil-soluble solvent, the quantity is 15 weight% or less with respect to the composition whole quantity.

  The solid content concentration of the electrodeposition coating composition (suspension type electrodeposition coating composition) used in the present invention is preferably 1 to 15% by weight, more preferably 5 to 10% by weight. The content of the water-soluble polar solvent is preferably 25 to 60% by weight, more preferably 35 to 55% by weight, based on the total amount of the composition.

  The electrodeposition coating composition (suspension-type electrodeposition coating composition) used in the present invention has high electrical conductivity during the film growth process, and is a member to be insulated (electrodeposited object) even under low current electrodeposition conditions. A highly uniform polyimide electrodeposition film having a film property can be formed on the surface, and as a result, an insulating film having excellent voltage resistance and heat resistance with a desired thickness can be formed with good reproducibility. In addition, since the dispersed particles (deposited particles) of the block copolymerized polyimide are likely to be deposited (attached) on the surface of the member to be insulated (electrodeposit), the electronic component (lead terminal) provided with the lead member as the member to be insulated Even if it is a member with a complicated shape that is not a single wire or flat plate, such as an electronic component), or a member with a mixture of insulating and conductive parts, it coats the conductive region where insulation protection of the member is to be achieved It is possible to form a polyimide film with high uniformity in film properties without producing defective portions with insufficient adhesion. In addition, a film having a thickness exceeding 30 μm can be formed.

  In the method for producing an insulating member according to the present invention, the electrodeposition coating is formed by immersing a member to be insulated (electrodeposit) in an electrodeposition coating composition, and passing the member (electrodeposit) as an anode through an electric current. A polyimide film may be grown on the member (electrodeposit).

  The material of the “insulated member” in the present invention is not particularly limited, and at least a part thereof is copper, copper alloy, copper grat aluminum, aluminum, iron, galvanized iron, silver, gold, nickel, titanium, tungsten, etc. The member comprised by 1 type, or 2 or more types of metals chosen from these is mentioned. Specifically, for example, when the insulating member to be manufactured is an insulated wire, the member to be insulated is a conductor wire such as copper wire, copper alloy, copper clad aluminum, aluminum, or stainless alloy, and the insulating member to be manufactured is insulated. In the case of electronic components with lead terminals, electronic components with lead terminals that are not insulated by copper-coated nickel steel wires (Jumet wires), nickel wires, Kovar wires, iron-nickel wires, Ni alloy wires, Ni-plated wires, etc. (Electronic components with lead terminals) and the like. In addition, the electronic component with a lead terminal here is a thermistor (temperature sensor), transformer, resistor, capacitor, inductor, piezoelectric element, crystal resonator, light emitting element (LED), cold cathode fluorescent lamp ( CCFL) is an electronic component in which a lead terminal is connected to an electrode of an element such as a diode by welding or soldering.

  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 electrodeposition 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 10-50 degreeC normally, Preferably it is 10-40 degreeC, More 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. In addition, if the electrodeposition time is shorter than 10 seconds, the film is difficult to grow even if the electrodeposition voltage is set high, so that pinholes are likely to occur, and the withstand voltage performance of the electrodeposition film tends to decrease, If it exceeds 120 seconds, the thickness of the coating becomes thicker than necessary, and 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 it is higher than 50 ° C., temperature management is required, which increases production costs.

  The block copolymerized polyimide film formed by electrodeposition is heat-dried (baked). In the present invention, the block copolymerized polyimide film formed by electrodeposition is treated with a water-soluble polar solvent and water and / or fat. Cleaning with a cleaning solution containing an aromatic alcohol solvent (preferably a cleaning solution comprising a mixture of a water-soluble polar solvent and water), and separating (removing) unnecessary cleaning solution from the coating by blowing air, and then heating the coating Dry (baked).

  By performing the cleaning process before heat drying (baking) of the film, the film after heat drying (baking) is made more uniform in film properties, and the adhesion to the member to be insulated and the insulating performance of the film are further improved. To do. In addition, when the member to be insulated is a member in which an insulating portion and a conductive portion are mixed due to the separation (removal) operation of the cleaning liquid by spraying air after cleaning, the insulation treatment member is substantially insulated. Can remove unnecessary paint components adhering to the area (insulating part) that does not need to be prevented, so that it is possible to prevent unnecessary foaming of the paint components during the heat drying (baking) of the electrodeposition coating, Further, the high adhesion of the electrodeposition film is maintained near the boundary between the conductive portion and the insulating portion.

  Further, for example, in the case of an electronic component having a lead terminal, as will be described later, the electronic component body (for example, the thermistor element) and the connection portion between the terminal electrode and the lead terminal of the electronic component body are sealed with ceramic or glass. However, when covering the lead terminal protruding from the sealing part with ceramic or glass with the electrodeposition coating from the base of the lead terminal, the vicinity of the base of the lead terminal should be located at the boundary with the ceramic or glass. Therefore, the adhesion of the film tends to decrease. However, by performing the cleaning treatment of the coating with the above cleaning solution and the removal of the cleaning solution with air before the coating is heated and dried (baked), the adhesion of the coating after heating and drying (baking) is increased and the coating is prevented from peeling off. can do.

  A film having a more preferable property can be formed by a cleaning operation with a cleaning liquid performed before heat drying (baking) of the electrodeposited film. The cleaning liquid contains a water-soluble polar solvent and water and / or an aliphatic alcohol solvent as the cleaning liquid. (Preferably a mixture of a water-soluble polar solvent and water). When the cleaning liquid is a water-soluble polar solvent, not only the separation (removal) of the paint remaining in the film after electrodeposition but also the coating If the cleaning solution is water and / or an aliphatic alcohol solvent, dissolution of the good solvent in the coating causes a decrease in the adhesion of the coating, and the coating film after heat drying (baking) The properties cannot be improved. The reason why the film properties of the coating after heat drying (baking) is improved by using a cleaning solution containing a water-soluble polar solvent and water and / or an aliphatic alcohol solvent is not clear. When the cleaning liquid in which the water-soluble polar solvent as the solvent and the poor solvent for the block copolymerized polyimide and / or the aliphatic alcohol solvent are in contact with the coating, the particles of the block copolymerized polyimide in the coating It is considered that this is because, as the binding force increases, the paint (liquid component) remaining in the coating is appropriately reduced, and the densification of the coating by heat drying (baking) is further increased.

  Examples of the water-soluble polar solvent include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), γ-butyrolactone (γBL), Anisole, tetramethylurea, sulfolane and the like can be mentioned, and any one or more of these can be used. Among these, N-methylpyrrolidone (NMP) is particularly preferable. Moreover, 1-propanol, isopropyl alcohol, ethylene glycol, propylene glycol etc. are mentioned as an aliphatic alcohol solvent, Any 1 type (s) or 2 or more types can be used.

  The mixing ratio of the water-soluble polar medium to water and / or the aliphatic alcohol solvent in the cleaning liquid is preferably 50 to 80% by weight of the water-soluble polar medium and 20 to 50% by weight of water and / or the aliphatic alcohol solvent, more preferably. Is 60 to 80% by weight of water-soluble polar medium and 20 to 40% by weight of water and / or aliphatic alcohol solvent, and particularly preferably 60 to 75% by weight of water soluble polar medium and water and / or aliphatic alcohol solvent. 25 to 40% by weight. When the water-soluble polar medium exceeds 80% by weight, the film formed by electrodeposition is dissolved, and the thickness of the film is significantly reduced. When the water and / or aliphatic alcohol solvent exceeds 50% by weight, the appearance of the film (shine ) Or roughness of the film, and in some cases, cracks may occur.

  In addition, when water and an aliphatic alcohol solvent are used as a poor solvent for the block copolymerized polyimide, the mixing ratio (water: aliphatic alcohol solvent) of both is about 1: 0.1 to 5 by weight ratio. Is preferred.

  The cleaning treatment with the cleaning liquid can be performed by immersing the member to be insulated having a film formed by electrodeposition on the surface in the cleaning liquid or by spraying the cleaning liquid on the coating. For example, in the case of immersion in a cleaning solution, the cleaning treatment time is generally about 1 to 30 seconds. If it is longer than 30 seconds, the film thickness may decrease or the coating may become non-uniform due to re-dissolution of the precipitated resin. If it is shorter than 1 second, the film thickness tends to become non-uniform due to insufficient cleaning. Become.

  On the other hand, the separation (removal) process of the cleaning liquid by spraying air can be performed by, for example, an air gun or the like, and generally depends on the spray pressure of the air gun, but generally the spraying time is preferably about 1 to 30 seconds. . If the spraying time exceeds 30 seconds and becomes too long, the coating appearance (gloss) will deteriorate and the coating will become rough, and in some cases it will tend to crack, and if it is shorter than 1 second, the cleaning liquid will be removed. It becomes insufficient and tends to cause appearance defects such as foaming.

  Heat drying (baking) is performed at a temperature of 160 to 180 ° C. for 10 to 60 minutes after performing a first stage baking process at 70 to 110 ° C. for 10 to 60 minutes from the viewpoint of adhesion of the film to the member to be insulated. It is preferable to perform a second stage baking process for 30 minutes, and further perform a third stage baking process at 200 to 220 ° C. for 30 to 60 minutes.

  The polyimide film obtained by heating and drying (baking) the electrodeposition film (coating) in this way is excellent in flexibility with which it is firmly adhered to the member to be insulated and is not easily cracked. For example, the AC withstand voltage according to the B method metal foil method in accordance with JIS-C-3003 is 1 kV or more when the layer thickness is 10 μm, 2 kV or more when the layer thickness is 20 μm, and 3 kV when the layer thickness is 30 μm. It becomes an insulating layer having a high electric resistance as shown above, and, for example, a temperature index according to a temperature index evaluation method based on JIS-C-3003 is 200 ° C. or higher (that is, the heat resistance category is C class or higher). It becomes an insulating layer having a high heat resistance as shown. Further, the elongation measured according to JIS-C-2151 is 5% or higher, preferably 8% or higher.

  The electrodeposition coating composition proposed in Patent Document 4 includes the present invention in that it contains a block copolymer polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule as a resin component. This is the same as the above suspension type electrodeposition coating composition used in the above, but it is a liquid phase dispersion or solution type composition in which block copolymerized polyimide does not exist as precipitated particles (solid particles), and a mixed system of several kinds of solvents Therefore, the behavior as an electrodeposition coating is greatly changed by a slight change in the mixing ratio of the solvent, and the film properties of the obtained electrodeposition coating are difficult to be uniform. For this reason, the heat resistance classification based on the temperature index evaluation method based on JIS-C-3003 is the highest, and only F-type electrodeposition coatings (insulating layers) can be formed, and the B-method metal foil conforming to JIS-C-3003 The AC withstand voltage when the layer thickness by the method is 10 μm shows at most only about 0.3 kV. Even if the electrodeposition conditions are variously changed, it is difficult to form an electrodeposition film (insulating layer) having a thickness exceeding 30 μm. In particular, when a relatively thin film having a thickness of about 5 to 15 μm is formed, variation in the insulation performance of the film with respect to the film thickness is large, and a film having a desired voltage resistance cannot be formed with good reproducibility.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by the following Example.

Example 1
[Preparation of electrodeposition coating composition]
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., 3 , 5-Diaminobenzoic acid 30.43 g (200 mmol), NMP 531 g and toluene 50 g were added and reacted for 8 hours while stirring at 180 ° C. and 180 rpm. By removing the refluxed product out of the system, a 20 wt% polyimide solution (20% polyimide varnish) was obtained. The number average molecular weight and weight average molecular weight of the obtained polyimide were 24,000 and 68,000, respectively.

  The obtained polyimide varnish was applied on a glass plate with a wet film thickness of 50 μm using a bar coater. Then, after drying at 90 ° C./30 minutes, 180 ° C./30 minutes, 220 ° C./30 minutes with a hot air drier, peel from the glass plate, and measure the mechanical elongation according to JIS C 2151. 21.8% of polyimide film was obtained. The thermal decomposition temperature was 420 ° C.

  100 g of the 20% polyimide varnish obtained above was stirred at 160 ° C. for 1 hour in a nitrogen atmosphere, and then rapidly cooled to 30 ° C., 59.4 g of N-methylpyrrolidone and 2.2 g of piperidine (neutralization rate 200 mol%) And stirred vigorously. Thereafter, the mixture was stirred while adding 129 g of propylene glycol monomethyl ether, and 67 g of water was added dropwise to prepare an electrodeposition solution. Using a particle size analyzer ELS-Z2 (manufactured by Otsuka Electronics Co., Ltd.), when the particle size and standard deviation of the dispersed particles in the electrodeposition solution were measured, precipitated particles having a particle size of 0.7 μm and a standard deviation of 0.5 μm A suspension having (solid particles) was formed. In addition, it was a black turbid liquid with a solid content concentration of 6.0%, pH of 8.7, and electric conductivity of 7.3 mS / m. The intrinsic log viscosity was 50 mPas.

[Production of insulated wires]
Using the above electrodeposition liquid composition, the distance between the electrode and the adherend is 25 mm, the electrodeposition voltage is 30 to 50 V, the electrodeposition current is 0.01 to 200 mA, and the electrodeposition time is 10 to 60 seconds. The electrode was electrodeposited on the outer periphery of a circular copper wire having a diameter of 1.0 mm and a length of 20 cm, and the electrodeposited copper wire was taken out from the electrodeposition bath. Next, the circular copper wire on which the film was formed by the above electrodeposition was dipped in a cleaning solution consisting of 70% by weight of N-methylpyrrolidone (NMP) and 30% by weight of water for 3 seconds, and air was sprayed by an air gun. The cleaning solution was removed. After that, 90 ° C. × 30 minutes, 170 ° C. × 30 minutes, and 220 ° C. × 30 minutes, the coating is baked to form a circular insulated copper wire having polyimide coatings (insulating layers) of various thicknesses (number of samples per condition) = 10) was obtained.

  And about the obtained circular insulated copper wire, the electrodeposition property (the state of the coating) of the electrodeposition liquid, the thickness of the coating, the AC withstand voltage and the heat resistant life of the coating were evaluated by the following test methods. The results are shown in Table 1 below.

1. State of coating The presence or absence of pinholes was investigated in accordance with JIS-C-3003.

2. The thickness of the coating was measured using a micrometer (minimum scale: 0.1 mm). The thicknesses of five locations separated by an interval of 2 cm per sample were measured, and the average value was taken as the measurement result of the sample.

3. AC breakdown voltage of coating The AC breakdown voltage was measured by the B method metal foil method in accordance with JIS-C-3003. That is, 1 cm of tin foil was wound around an insulated wire and measured between the conductor and tin foil. Then, an AC voltage generator was connected to each plate, the voltage was increased at a rate of 100 V per second, and the short-circuited voltage (leakage current value of 10 mA or more) was taken as the breakdown voltage. Table 1 shows the average value, maximum value, and minimum value of 10 samples.

4). Heat resistant life of coating For a sample (test No. 3) having a film thickness of 21 μm of insulated wire, the heat resistance of the insulated wire (heat resistant life of the electrodeposited coating) in accordance with the temperature index evaluation method described in JIS-C-3003 ) Was evaluated. That is, two test pieces were obtained by twisting two using two wire samples. This test piece was heat-treated in an oven set at a temperature of 290 to 320 ° C. at intervals of 10 ° C. (290 ° C., 300 ° C., 310 ° C., 320 ° C.), and each was destroyed by applying a voltage of 500 V × 1 second. The time to reach was measured. The temperature index was calculated from a heat resistant life graph in which the measurement results at temperatures of 290 ° C., 300 ° C., 310 ° C., and 320 ° C. were Arrhenius plotted. The heat-resistant temperature corresponding to a life of 20,000 hours, that is, the temperature index is 240 ° C., and the heat-resistant classification corresponds to Class C having a temperature of 200 ° C. or higher.

Comparative Example 1
After 100 g of a semisolid composition containing 20% by weight of the block copolymerized polyimide (resin component) obtained in Example 1 was heated and melted at 160 ° C., 70 g of NMP was added, 55 g of anisole, 45 g of cyclohexanone and N-methyl were added. 2.6 g of morpholine (neutralization rate: 200 mol%) was added, and 30 g of water was added dropwise with stirring to obtain an electrodeposition liquid composition having a solid content concentration of 6.6% and a pH of 7.8. Using a particle size analyzer ELS-Z2 (manufactured by Otsuka Electronics Co., Ltd.), the particle size and standard deviation of the dispersed particles in the electrodeposition liquid were measured, but no precipitated particles having a particle size of 0.1 μm or more were observed. . And using this electrodeposition liquid composition, the distance between electrodes is 25 mm, the electrodeposition voltage is 160 V, the electrodeposition current is in the range of 0.01 to 200 mA, and the electrodeposition time is in the range of 10 to 60 seconds. Then, electrodeposition was performed on the same copper wire as the circular copper wire used in Example 1, the copper wire after electrodeposition was taken out from the electrodeposition bath, and the coating was washed and coated under the same conditions as in Example 1. Then, a circular insulated copper wire (number of samples per condition = 10) having polyimide coatings (insulating layers) with various thicknesses was obtained. And by the above-mentioned test method, the electrodeposition property (the state of the coating) of the electrodeposition liquid, the thickness of the coating, the AC withstand voltage, and the heat resistant life of the coating were evaluated. The results are shown in Table 2 below. The heat resistant life of the film was measured on a sample having a polyimide film thickness of 18 μm. The temperature index was 180 ° C. and the heat resistance category was H.

  FIG. 1 shows the relationship between the coating thickness of the circular insulated copper wire (sample) produced in Example 1 and Comparative Example 1 and the AC withstand voltage. In addition, in Reference Example 1 in FIG. 1, the relationship between the film thickness and the AC withstand voltage in a circular insulated copper wire (sample) produced in the same manner as in Example 1 except that the electrodeposition film was washed before baking with water. It is.

  As shown in FIG. 1, by using a suspension type electrodeposition coating composition, it is possible to form an insulating film having a high voltage resistance compared to the case of using a conventional liquid phase dispersion or solution type electrodeposition coating composition. I understand. Further, from the comparison of Table 1 and Table 2, the use of the suspension type electrodeposition coating composition allows the electrodeposition coating to be compared with the case where a conventional liquid phase dispersion or solution type electrodeposition coating composition is used. It can be seen that the variation in withstand voltage with respect to the film thickness is small (that is, the difference between the maximum value and the minimum value of the AC withstand voltage of the film having substantially the same thickness obtained under the same conditions is small). In the method of the present invention (Example 1) in which the coating is washed with a cleaning liquid composed of a mixed solution of N-methylpyrrolidone (NMP) and water before baking the electrodeposition coating with the suspension type electrodeposition coating composition, the suspension type The voltage resistance of the film is further improved as compared with the case where the film is washed with water before baking the electrodeposition film with the electrodeposition coating composition (Reference Example 1), and the correlation between the film thickness and the AC voltage resistance is increased. It turns out that it improves further. Therefore, according to the method of the present invention, it can be seen that an insulating member having an intended thickness and having an insulation treatment with an insulating film having high voltage resistance and heat resistance can be manufactured with high yield.

Example 2
[Production of thermistor with insulated lead terminals]
A conductive paste containing Au powder is used for the terminal electrode of the thermistor element (negative thermistor element formed by opposing the terminal electrodes made of Au on both sides) 1 shown in FIG. One end of a lead terminal 2 made of a copper-coated nickel steel wire (Jumet wire) with a diameter of 0.4 mm and a length of 80 mm is connected to the thermistor element 1 and the terminal electrode of the thermistor element 1 and the connection portion of the lead terminal 2 with a low melting point glass. A thermistor with lead terminals by mounting a glass tube (outer diameter 1.35 mm, inner diameter 1.05 mm, length 3.0 mm) made of (softening point 570 ° C.), followed by heating at 750 ° C. for 3 minutes and glass sealing. 5 was prepared. This thermistor 5 with lead terminals is left in the electrodeposition coating composition produced in Example 1 filled with an electrodeposition bath, with a length of 50 mm at the tip of the lead terminal 2 from the component body (thermistor 1) side. Immersion was performed, the voltage was 30 V, the energization amount was 0.05 to 0.2 C, and an electrodeposition film was formed. The electrodeposition current value at that time was changed within the range of 0.01 to 200 mA, and the electrodeposition time was changed within the range of 0.5 to 30 seconds. Next, the thermistor with a lead terminal formed by coating the lead terminal by the above electrodeposition in a cleaning solution composed of 75% by weight of N-methylpyrrolidone (NMP) and 25% by weight of water is dipped for 3 seconds and pulled up with an air gun. Was sprayed to remove the cleaning solution. Then, by baking the film at 90 ° C. × 30 minutes, further at 170 ° C. × 30 minutes, and further at 220 ° C. × 30 minutes, leaving the 50 mm length portion on the tip side of the lead terminal 2 shown in FIG. A thermistor with an insulated lead terminal 10 in which the lead terminal 2 was coated with a polyimide coating (insulating coating) 4 was obtained (number of samples per condition = 10).

  The film thickness of the thermistor with insulated lead terminals thus prepared was measured, and the AC withstand voltage of the coating film was evaluated.

  The thickness of the coating was measured using a micrometer (minimum scale: 0.1 mm). The thickness of three places spaced at intervals of 5 mm per sample was measured, and the average value was taken as the measurement result of the sample. The AC withstand voltage of the coating was measured by the following underwater method.

[AC withstand voltage measurement method (underwater method)]
As shown in FIG. 4, the water 67 was previously filled with the water tank 66 in which the electrode 68 was installed. There, the thermistor 10 with lead terminals was arranged so that the covered portion of the lead terminal 2 with the insulating coating 4 was immersed in water 67 and the boundary between the covered portion and the uncovered portion was located near the water surface. In addition, the vicinity of the boundary where the lead terminal (Jumet wire) was exposed from the insulating coating 4 was masked with the insulating tape 64 in advance, and the boundary portion between the sealing glass 3 and the lead terminal 2 was masked with the insulating tape 65. The masking with the tape is to prevent measurement errors caused by the contact of the lead terminals (jumet wires) directly with the water 67 in the vicinity thereof. In this configuration, the length of the insulating coating 4 in contact with the water 67 was 28 mm. In this state, an AC voltage was applied between the electrode 68 and the lead terminal 2 from the AC power source 69, and a voltage value causing dielectric breakdown was determined.

  Table 3 below shows the measurement results, and the film thickness and AC withstand voltage are average values of 10 samples under each test condition.

Reference example 2
A thermistor with an insulated lead terminal was prepared in the same manner as in Example 2 except that the cleaning liquid was changed to water, the film thickness was measured, and the AC withstand voltage of the coating was evaluated. The results are shown in Table 4 below. The film thickness and AC withstand voltage in the table are average values of 10 samples under each test condition.

FIG. 3 is a graph showing the relationship between the film thickness and the AC withstand voltage from the results of Tables 3 and 4.
From FIG. 3, in the Example using the mixed liquid of N-methylpyrrolidone and water as the cleaning liquid, the film after baking shows higher withstand voltage with respect to Reference Example 2 using water as the cleaning liquid. Thus, according to the method of the present invention, it can be seen that an electronic component with an insulated lead terminal in which the lead terminal is insulated with an insulating coating having an extremely excellent electrical insulation property can be manufactured.

FIG. 1 is a graph showing the relationship between the thickness of the electrodeposition coating and the AC withstand voltage in Example 1, Comparative Example 1, and Reference Example 1. 2A and 2B are schematic views for explaining a method for manufacturing a thermistor with insulated lead terminals. FIG. 3 is a graph showing the relationship between the thickness of the electrodeposition coating and the AC withstand voltage in Example 2 and Reference Example 2. It is explanatory drawing of AC withstand voltage measuring method (underwater method).

Explanation of symbols

1 Thermistor element 2 Lead terminal 3 Glass (sealing glass)
4 Polyimide coating 5 Thermistor with lead terminal 10 Thermistor with insulated lead terminal

Claims (11)

A member to be insulated is immersed in a suspension-type electrodeposition coating composition containing a block copolymer polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule as a resin component. An anionic electrodeposition step of growing a polyimide film on the surface of the member through an electric current as an anode;
Cleaning the insulating member having the polyimide coating with a cleaning liquid containing a water-soluble polar solvent and water and / or an aliphatic alcohol solvent;
A step of spraying air on the member to be insulated having the polyimide coating to remove the cleaning liquid;
And a step of drying the polyimide coating.   The method for producing an insulating member according to claim 1, wherein the cleaning liquid contains 50 to 80% by weight of a water-soluble polar solvent and 20 to 50% by weight of water and / or an aliphatic alcohol solvent.   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 manufacturing method of the insulating member of Claim 2 which is 1 type, or 2 or more types chosen from methylurea and sulfolane.   The manufacturing method of the insulating member of any one of Claims 1-3 whose block copolymerization polyimide is a polyimide containing the diamine which has a siloxane bond in molecular skeleton as one of the diamine components. Diamines having a siloxane bond in the molecular skeleton include bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane, and The manufacturing method of the insulating member of Claim 4 which is 1 type, or 2 or more types chosen from the group which consists of a compound represented by Formula (I).

(In the formula, four R's each independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxyl 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.)   Four R in the general formula (I) are each independently an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, a phenyl group, or 1 to 3 carbon atoms having 1 to 3 carbon atoms. The method for producing an insulating member according to claim 5, which represents a phenyl group substituted with an alkyl group having 6 or an alkoxyl group having 1 to 6 carbon atoms.   The insulating member according to any one of claims 1 to 6, wherein the anionic group in the molecule of the block copolymerized polyimide is a carboxylic acid group or a salt thereof, and / or a sulfonic acid group or a salt thereof. Production method.   The manufacturing method of the insulating member of any one of Claims 1-7 whose block copolymer polyimide contains aromatic diaminocarboxylic acid as one of the diamine components.   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 sum of both is The method for producing an insulating member according to claim 8, which is 100 mol% or less and may contain a third diamine component.   The method for manufacturing an insulating member according to any one of claims 1 to 9, wherein the insulating member is an insulated wire and the member to be insulated is a conductor wire.   The method for manufacturing an insulating member according to any one of claims 1 to 9, wherein the insulating member is an electronic component with an insulated treatment lead terminal, and the insulated member is an electronic component with a lead terminal.

Images