JP5259041B2 - Resin composition and aqueous electrodeposition coating - Google Patents

Description

  The present invention relates to a resin composition containing at least polyimide particles and a hydrophilic cationic polymer, and an aqueous electrodeposition coating using the resin composition.

  The electrodeposition coating method is a method of coating the surface of an object to be coated by immersing the object to be coated, such as a metal product, in a current-carrying tank filled with a coating called an electrodeposition paint, and energizing it. However, since it can be applied uniformly, it is frequently used in various fields such as the electronic equipment field.

  Electrodeposition paints are required to have various properties depending on the application, such as excellent insulation, heat resistance, and wear resistance of the coating film. In particular, in the electronic equipment field, excellent heat resistance is required.

  Examples of the electrodeposition paint for the purpose of improving heat resistance include a neutralized salt of polyamic acid obtained by neutralizing polyamic acid with an alkali such as amine, and the neutralized salt is electrodeposited on the anode side. An anionic electrodeposition coating composition, an anionic electrodeposition coating composition that includes a polyimide resin ring-closed by block copolymerization and deposits the polyimide resin on the anode have been proposed (for example, see Patent Document 1). ).

  Since the resin contained in the electrodeposition paint disclosed in Patent Document 1 is an anionic type, there is a problem that the object to be coated needs to be used as an anode, and dissolution of the object to be coated occurs. For this reason, electrodeposition coatings using these resins cannot be used for coatings that require insulation, such as when coating metals such as copper and silver plating used in electronic components. Further, since these resins are difficult to disperse or dissolve in water, N-methylpyrrolidone (abbreviation: NMP), N, N-dimethylformamide (abbreviation: DMF), N, N-dimethylacetamide, which has excellent solubility in these resins (Abbreviation DMAc) and aprotic polar organic solvents such as cresols must be used in a large amount of 50% by weight or more of the total amount of the electrodeposition paint, which is problematic in terms of safety and environment.

  As described above, since there are various problems with electrodeposition paints using anionic resins, electrodeposition paints using cationic resins have been studied. For example, as an electrodeposition coating using a cationic polyimide resin, an organic solvent-soluble polyimide varnish solution and a hydrophilic polymer such as a hydrophilic cationic polymer are mixed and reacted in an organic solvent in a solution state. A polyimide-based aqueous dispersion obtained by mixing the obtained reaction solution with an aqueous medium has been proposed (see Patent Documents 2 and 3).

  Since the polyimide-based aqueous dispersions disclosed in Patent Documents 2 and 3 are obtained through a process of reacting a polyimide varnish and a hydrophilic polymer, it is necessary to control the reaction, and the manufacturing process becomes complicated. There's a problem. In addition, since it is necessary to select a material in consideration of reactivity, there is a problem that the types of usable materials are limited and it is difficult to adjust characteristics.

  As a technique for solving this problem, a polycondensation polyimide resin, a thermally cross-linked polyimide resin, and a hydrophilic cationic polymer are dispersed in water at a predetermined ratio, thereby making the polycondensation polyimide resin a hydrophilic cationic polymer. It has been proposed to disperse in water without reacting (see Patent Document 4).

  In addition to the above heat resistance and insulation properties, the electrodeposition paint used as an insulating paint on the circuit board is also required to have moisture resistance so that the coating film does not change in dimensions due to moisture absorption. When a dimensional change occurs in the insulating coating film covering the wiring of the circuit board, there is a possibility that a short circuit of the wiring or the like occurs.

  In addition, for the purpose of downsizing the circuit board, a wire having a rectangular cross-sectional shape called a flat electric wire is often used, and the electrodeposition paint has an end portion (hereinafter referred to as an edge portion) of the flat electric wire. To be uniformly coated, that is, excellent edge covering properties are also required.

  The technique disclosed in Patent Document 4 does not consider moisture resistance and edge covering properties, and requires the development of an electrodeposition coating material that also considers moisture resistance and edge covering properties.

JP-A-9-124978 JP 11-49951 A JP 2000-34352 A JP 2000-268235 A

  An object of the present invention is to realize an aqueous electrodeposition coating material capable of forming a coating film excellent in all of heat resistance, insulation, safety, moisture resistance and edge covering property, and the aqueous electrodeposition coating material. It is to provide a resin composition.

  In the course of research to solve the above-mentioned problems, the present inventor says that the polar organic solvent contained in the water-based electrodeposition paint causes dimensional change of the coating film due to moisture absorption and deterioration of the edge covering property. Obtained knowledge. As a result of further research based on such knowledge, a novel amount capable of reducing the amount of the polar organic solvent contained in the aqueous electrodeposition paint without lowering the dispersibility of the resin in the aqueous electrodeposition paint. The present invention was completed.

That is, the present invention is a resin composition comprising polyimide particles, either an organic solvent solution of polyimide or an organic solvent solution of polyimide prepolymer, and a hydrophilic cationic polymer , 5 to 80 parts by weight of the polyimide particles and the hydrophilic so that the total amount of the polyimide particles, the hydrophilic cationic polymer, and the polyimide or the polyimide prepolymer is 100 parts by weight in terms of solid content. 15 to 80 parts by weight of the cationic cationic polymer, 5 to 80 parts by weight of the polyimide or the polyimide prepolymer,
A resin composition, wherein the average particle size of the poly Lee bromide particles is 1 to 6 m.

  In the present invention, the average particle diameter of the polyimide particles is 0.02 to 50 μm.

  The present invention is also characterized in that the average particle size of the polyimide particles is 2 to 20 μm.

The present invention is also characterized in that the polyimide particles have a thermally reactive group.
Further, the present invention is characterized in that the thermally reactive group is at least one of an amino group and an epoxy group.

  The present invention also provides an aqueous electrodeposition coating composition comprising the resin composition of the present invention, an acid neutralizing agent, and water.

  Further, the present invention is characterized in that the acid neutralizing agent is at least one of an organic acid and an inorganic acid.

  According to the present invention, there is provided a resin composition containing specific amounts of polyimide particles and hydrophilic cationic polymers.

  In the resin composition of the present invention, the polyimide particles are easily dispersed in water without using a polar organic solvent due to entanglement and compatibility with the hydrophilic cationic polymer and wettability of the hydrophilic cationic polymer to the polyimide particle surface. The Therefore, by using the resin composition of the present invention, the amount of the polar organic solvent in the aqueous electrodeposition coating can be reduced, so that the moisture resistance and edge covering properties are excellent, the safety is excellent, and the environment It is possible to realize a water-based electrodeposition paint with a low load on the water.

  Moreover, since the polyimide particles can suppress the fluidity of the coating film formed with the solution containing the polyimide particles, the solution containing the resin composition of the present invention is excellent in the ability to be applied to an object to be coated. Excellent edge covering. In addition, polyimide particles have excellent heat resistance, insulation and mechanical properties, as well as chemical resistance. can do. Furthermore, since the resin composition of the present invention contains specific amounts of polyimide particles and hydrophilic cationic polymers, respectively, the solution containing the resin composition of the present invention is particularly excellent in heat resistance and insulation after film formation.

  Accordingly, by using the resin composition of the present invention, an aqueous electrodeposition capable of forming a coating film excellent in any of heat resistance, insulation, moisture resistance and edge covering property on the metal surface being coated. A paint can be realized. The resin composition of the present invention is also useful as an impregnating resin material used for preparing a prepreg. For example, an appropriate base material is impregnated with a solution obtained by dissolving the resin composition of the present invention in an appropriate solvent. As a result, a prepreg excellent in heat resistance, insulation and moisture resistance can be obtained. Further, by using the resin composition of the present invention, it is possible to produce a film excellent in heat resistance and insulation by a casting method or a spin coating method, and heat resistance and insulation coating by a dipping method.

Further, the resin composition of the present invention further contains 5 to 80 parts by weight of either polyimide or an organic solvent solution of the prepolymer thereof in terms of solid content . The organic solvent solution of polyimide or the organic solvent solution of polyimide prepolymer is compatible with the polyimide particles and the hydrophilic cationic polymer, and can improve the dispersibility of the polyimide particles in water. In addition, the polyimide in the organic solvent solution and the prepolymer thereof are co-deposited on the electrodeposition coating film formed by the aqueous electrodeposition coating using the resin composition of the present invention containing these organic solvent solutions. Since the crosslinking reaction is caused by heating at the time of drying or baking, the heat resistance, insulation and abrasion resistance of the coating film can be improved. Therefore, by using the resin composition of the present invention containing an organic solvent solution of polyimide or a prepolymer thereof, an aqueous electrodeposition that can form a coating film that is particularly excellent in heat resistance and wear resistance on the surface of the metal to be treated. A paint can be obtained.

  Moreover, according to this invention, it is preferable that the average particle diameter of the polyimide particle contained in the resin composition of this invention is 0.02-50 micrometers. By selecting the average particle diameter of the polyimide particles in the range of 0.02 to 50 μm, the dispersibility of the polyimide particles in water can be improved. Therefore, the uniformity and surface smoothness of the coating film formed on the surface of the metal to be treated can be improved by the aqueous electrodeposition coating using the resin composition of the present invention. Moreover, the storage stability of the water-based electrodeposition coating using the resin composition of the present invention can be improved.

  Moreover, according to this invention, it is further more preferable that the average particle diameter of the polyimide particle contained in the resin composition of this invention is 2-20 micrometers. By selecting the average particle size of the polyimide particles in the range of 2 to 20 μm, the fluidity of the aqueous electrodeposition coating using the resin composition of the present invention is further suppressed, and the edge covering property of the coating film is improved. Can do.

  According to the present invention, the polyimide particles contained in the resin composition of the present invention preferably have a heat-reactive group, and have at least one of an amino group and an epoxy group among the heat-reactive groups. It is preferable. Here, the heat-reactive group is a functional group capable of reacting with other polyimide particles coexisting with the polyimide or a prepolymer thereof contained in the organic solvent solution when heated. By using the resin composition of the present invention containing polyimide particles having a heat-reactive group for an aqueous electrodeposition coating, the heat resistance, insulation and abrasion resistance of the coating film can be further improved. This is presumably because the polyimide particles in the coating film undergo a crosslinking reaction by heating such as drying or baking, and a rigid crosslinked structure is formed. Therefore, by using the resin composition of the present invention containing polyimide particles having a heat-reactive group, it is possible to realize an aqueous electrodeposition coating material that is particularly excellent in the heat resistance, insulation and abrasion resistance of the coating film.

  According to the present invention, the aqueous electrodeposition paint of the present invention comprises the resin composition of the present invention, an acid neutralizing agent, preferably at least one of an organic acid and an inorganic acid, and water. This realizes an aqueous electrodeposition coating material that can form a coating film having excellent heat resistance, insulating properties, moisture resistance and edge covering properties on the metal surface that is the object to be coated.

(Resin composition)
The resin composition of the present invention is a resin composition comprising polyimide particles, either an organic solvent solution of polyimide or an organic solvent solution of a polyimide prepolymer, and a hydrophilic cationic polymer, and the polyimide in the resin composition (A) 5 to 80 parts by weight of polyimide particles and (b) hydrophilic so that the total amount of particles, hydrophilic cationic polymer and polyimide or polyimide prepolymer is 100 parts by weight in terms of solid content It contains 15 to 80 parts by weight of a cationic polymer, and further contains 5 to 80 parts by weight of (c) polyimide or a prepolymer thereof.

  In the resin composition of the present invention, the polyimide particles are easily dispersed in water without using a polar organic solvent due to entanglement and compatibility with the hydrophilic cationic polymer and wettability of the hydrophilic cationic polymer to the polyimide particle surface. The Therefore, by using the resin composition of the present invention, it is possible to reduce the amount of polar organic solvent in the water-based electrodeposition paint described later, so that the moisture resistance and edge covering properties are excellent and the safety is excellent. In addition, it is possible to realize a water-based electrodeposition paint with a small environmental load.

  Moreover, since the polyimide particles can suppress the fluidity of the coating film formed with the solution containing the polyimide particles, the solution containing the resin composition of the present invention is excellent in the ability to be applied to an object to be coated. Excellent edge covering. In addition, polyimide particles have excellent heat resistance, insulation and mechanical properties, and are also excellent in chemical resistance and do not change in solvent, so that the coating film formed with a solution containing the polyimide particles has heat resistance, insulation and resistance. Abrasion can be imparted. Furthermore, since the resin composition of the present invention contains specific amounts of polyimide particles and hydrophilic cationic polymers, respectively, the solution containing the resin composition of the present invention is particularly excellent in heat resistance and insulation after film formation.

  Accordingly, by using the resin composition of the present invention, an aqueous electrodeposition capable of forming a coating film excellent in any of heat resistance, insulation, moisture resistance and edge covering property on the metal surface being coated. A paint can be realized. The resin composition of the present invention is also useful as an impregnating resin material used for preparing a prepreg. For example, an appropriate base material is impregnated with a solution obtained by dissolving the resin composition of the present invention in an appropriate solvent. As a result, a prepreg excellent in heat resistance, insulation and moisture resistance can be obtained. The resin composition of the present invention can also be used as a coating resin material used for film production by a casting method, spin coating method, etc., coating by a dipping method, and the like. By using the resin composition of the present invention in these methods, it is possible to produce a film having excellent heat resistance, insulation, etc., coating, and the like.

(A) Polyimide particle In this invention, a polyimide particle is a particle | grain containing a polyimide resin. The polyimide resin constituting the polyimide particles may be an oligomer. Polyimide resins are classified into the following three types according to thermal properties and molecular structure.

(1) Linear Thermoplastic Polyimide Resin The linear thermoplastic polyimide resin has a molecular structure that is linear (linear) and softens when heated and solidifies when cooled.

(2) Linear non-thermoplastic polyimide resin Although linear molecular non-thermoplastic polyimide resin has a linear molecular structure, it hardly softens even when heated, and has a clear glass transition point and melting point. Has the property of not showing.

(3) Thermosetting polyimide resin The thermosetting polyimide resin has a property that the molecular weight is small before curing by heating, and when heated, it has a three-dimensional network structure due to cross-linking to increase the molecular weight and cure.

  It does not specifically limit as polyimide resin which comprises a polyimide particle, The 1 type (s) or 2 or more types of polyimide resin classified into the above (1)-(3) can be used. Among them, the linear thermoplastic polyimide resin (1) and the linear non-thermoplastic polyimide resin (2) are preferably used.

  These polyimide resins are prepared by, for example, synthesizing polyamic acid by equimolar reaction of tetracarboxylic anhydride and a diamine compound in a suitable organic solvent, and imidizing the resulting polyamic acid by dehydrating ring-closing reaction. Can be obtained. In addition, it may replace with tetracarboxylic anhydride and may use dicarboxylic anhydrides, such as maleic anhydride, and may use these mixtures.

  The tetracarboxylic anhydride is not particularly limited, and those generally used for the synthesis of polyimide resins can be used. For example, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-benzosulfone tetracarboxylic dianhydride, 3,3 ′, 4,4′- Such as diphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, pyromellitic anhydride, etc. Aromatic tetracarboxylic dianhydride, aliphatic tetracarboxylic dianhydride such as butane-1,2,3,4-tetracarboxylic dianhydride, cyclobutane-1,2,3,4-tetracarboxylic dianhydride Examples thereof include alicyclic tetracarboxylic dianhydrides such as anhydrides, and heterocyclic tetracarboxylic dianhydrides such as thiophene-2,3,4,5-tetracarboxylic dianhydride. Also aromatic tetracarboxylic dianhydride is suitably used. One tetracarboxylic anhydride may be used alone, or two or more may be used in combination.

  Also as a diamine compound, it does not restrict | limit in particular, What is generally used for the synthesis | combination of a polyimide resin can be used. For example, p-phenylenediamine, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 1,3-bis (4-aminophenoxy) benzene, 2,2 ′-[4- (4-amino Phenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl ] Sulfones, aromatic diamines such as 2,2-bis [4- (4-aminophenoxy) phenyl] propane, aliphatic diamines such as 1,2-diaminomethane, and alicyclic diamines such as 1,4-diaminocyclohexane , Heterocyclic diamines such as 3,4-diaminopyridine, 1,4-diamino-2-butanone, etc. Min is preferably used. A diamine compound may be used individually by 1 type, and 2 or more types may be used together.

  Among these, for example, by using 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride as tetracarboxylic anhydride and 4,4′-diaminodiphenyl ether as diamine compound, the above-mentioned (1 ) Linear thermoplastic polyimide resin can be obtained.

  The linear non-thermoplastic polyimide resin (2) can be produced, for example, by using pyromellitic anhydride as the tetracarboxylic anhydride and p-phenylenediamine as the diamine compound.

  In addition, the thermosetting polyimide resin (3) uses, for example, 3,3′-4,4′-benzophenonetetracarboxylic dianhydride as tetracarboxylic anhydride, and maleic anhydride as dicarboxylic anhydride, It can be produced by using 4,4′-diaminodiphenyl ether as the diamine compound.

  As a method for producing the polyimide particles, Journal of the Japan Adhesion Society (2002, 38, 269), Japanese Patent No. 3478977, Japanese Patent Laid-Open No. 10-322140, Japanese Patent Laid-Open No. 2000-248063, Osaka Prefectural Sangyo Technical sheet NO. 98053, Polymer Journals (2000, Vol. 57, No. 5, page 271), etc., for example, a chemical method for phase separation of particles from a reaction system during polymerization of polyimide, A polyamic acid varnish solution, which is a precursor of polyimide, is phase-separated by mixing with a poor solvent to prepare polyamic acid particles, and the prepared polyamic acid particles are imidized to prepare polyimide particles. Typical examples thereof include a method, a method in which a soluble polyimide varnish solution is phase-separated by mixing with a poor solvent to precipitate polyimide particles.

  Among these, Japanese Patent No. 3478977, Japanese Patent Laid-Open No. 10-322140, Japanese Patent Laid-Open No. 2000-248063, Technical Sheet No. issued by Osaka Prefectural Industrial Technology Research Institute. Since the manufacturing method described in 98053, the collection of polymer papers (2000, Vol. 57, No. 5, page 271) can obtain polyimide particles having a uniform particle diameter from nanometer size to micrometer size, This is particularly effective in the present invention.

  According to the method for producing polyimide particles described in these documents, for example, after the polyimide particles are granulated in the state of polyamic acid which is a polyimide prepolymer, the polyimide particles are heated and imidized while maintaining the form. Manufactured by. Specifically, first, a predetermined amount of each of the raw material diamine compound and tetracarboxylic anhydride is separately dissolved in a reaction solvent, and both are mixed and reacted while irradiating ultrasonic waves to prepare polyamic acid particles. The produced polyamic acid particles are separated by centrifugal separation, and purified by repeatedly washing with a reaction solvent. As the reaction solvent for dissolving the diamine compound and the reaction solvent for dissolving the tetracarboxylic anhydride, it is necessary to use a solvent that dissolves the raw material diamine compound or tetracarboxylic anhydride but does not dissolve the product polyamic acid. . Examples of such a solvent include alcohols such as methanol and ketones such as acetone.

  Next, after the obtained polyamic acid particles are dispersed in a suitable solvent, they are refluxed for 3 to 5 hours, preferably 4 hours to imidize to obtain polyimide particles. As the solvent for the imidization reaction, it is preferable to use a solvent that does not affect the polyamic acid and polyimide chemically and physically, has a boiling point that is equal to or higher than the imidization temperature of the polyamic acid, and azeotropes with water. Examples of such a solvent include aromatic hydrocarbons such as xylene and alcohols such as dodecane. In addition, the imidation temperature of a polyamic acid is 135 degreeC or more with the polyamic acid generally used for manufacture of a polyimide resin.

  Further, as another method, for example, a method of heating and imidizing a varnish solution of an aprotic polar solvent of polyamic acid, which is a polyimide prepolymer, to precipitate the polyimide as particles may be mentioned. In this method, first, a predetermined amount of each of a diamine compound and a tetracarboxylic anhydride is polymerized in an aprotic polar solvent, for example, at room temperature (about 20 to 30 ° C.) to prepare a polyamic acid varnish. Examples of the aprotic polar solvent used in the polyamic acid synthesis reaction include N, N-dimethylformamide (abbreviation DMF), N, N-dimethylacetamide (abbreviation DMAc), and N-methylpyrrolidone (abbreviation NMP). .

  Next, a predetermined amount of an azeotropic solvent such as toluene is added to the obtained polyamic acid varnish, and the mixture is refluxed with stirring at a constant rate to perform imidization, thereby obtaining polyimide particles. Here, the azeotropic solvent is a solvent that can be azeotroped with water. The end of the imidation reaction can be determined by the presence or absence of water generation. For example, the precipitation of the imidized particles starts from about 30 minutes to 1 hour from the start of reflux, the production of water is completed in about 3 hours from the start of reflux, and the reaction is almost finished in about 4 hours. After completion of the reaction, the precipitated polyimide particles are separated by filtration or centrifugation, and purified by washing with a reaction solvent, methanol, acetone or the like. Adding an azeotropic solvent such as toluene to the polyamic acid varnish distills off the water produced during the imidization reaction to the outside of the reaction system by azeotropic distillation, and hydrolyzes the unreacted polyamic acid moiety. It is effective to reduce.

  The polyimide particles obtained as described above can impart heat resistance and insulating properties to a water-based electrodeposition coating described later produced using the resin composition of the present invention.

  When the aqueous electrodeposition coating composition of the present invention to be described later is prepared using the resin composition of the present invention, the solution containing the resin composition is not heated or the heating temperature is not as high as about 50 ° C., for example. The polyimide particles are not melted and the particle shape is maintained in the aqueous electrodeposition coating.

  It is preferable that the average particle diameter of a polyimide particle is 0.02-50 micrometers (0.02 micrometer or more and 50 micrometers or less), More preferably, it is 2-20 micrometers (2 micrometers or more, 20 micrometers or less). Polyimide particles having an average particle diameter within the above range are excellent in dispersibility in water. Therefore, by using such polyimide particles, the storage stability of the aqueous electrodeposition coating composition of the present invention described later, and the coating film Uniformity and surface smoothness can be improved. In particular, polyimide particles having an average particle diameter in the range of 2 to 20 μm are excellent in the effect of suppressing the fluidity of the aqueous electrodeposition paint, and can improve the edge covering property of the coating film. It is done.

  The coefficient of variation of the polyimide particles is preferably 1 to 50% (1% or more and 50% or less), more preferably 1 to 20% (1% or more and 20% or less). The coefficient of variation indicates that the smaller the value, the smaller the variation in particle diameter. By using polyimide particles having a coefficient of variation within the above range, the dispersibility of the polyimide particles in the aqueous electrodeposition coating described later is improved, and the storage stability, coating uniformity and surface smoothness are further improved. Can do.

  The polyimide particles may have a functional group such as a thermally reactive group. In particular, the polyimide particles having at least one of a heat-reactive group, preferably an amino group and an epoxy group, are used in the aqueous electrodeposition coating described later using the resin composition of the present invention. Since abrasion resistance can be improved, it is used suitably. This is because the thermally reactive groups of the polyimide particles contained in the coating film cause a crosslinking reaction by heating such as drying or baking of the coating film, and a rigid crosslinked structure is formed in the coating film. Inferred.

  The polyimide particles may be used in a solid state or may be used as a dispersion liquid dispersed in an organic solvent.

  In order to exert the effect of the present invention, the blending amount of the polyimide particles in the resin composition of the present invention is 5 to 80 parts by weight (5 to 80 parts by weight) in terms of solid content. is necessary. When the blending amount of the polyimide particles is less than 5 parts by weight, sufficient heat resistance and insulation cannot be imparted to the coating film formed by the aqueous electrodeposition coating. Moreover, when the compounding quantity of a polyimide particle exceeds 80 weight part, it will become difficult to disperse | distribute or melt | dissolve the resin composition of this invention in water.

  The compounding amount of the polyimide particles is more preferably 5 to 70 parts by weight (5 parts by weight or more and 70 parts by weight or less), more preferably 10 to 60 parts by weight (10 parts by weight or more and 60 parts by weight) in terms of solid content. Part or less).

(B) Hydrophilic cationic polymer In the present invention, the hydrophilic cationic polymer is a polymer having a cationic hydrophilic group, and the cationic hydrophilic group is a hydrophilic group that forms a cationic group in water. . Examples of the cationic hydrophilic group include substituted or unsubstituted amino groups such as amino groups, primary amino groups, and secondary amino groups, quaternized salts thereof, hydroxyl groups, and the like.

  The hydrophilic cationic polymer is not particularly limited as long as it is a resin having the above-described cationic hydrophilic group, and a known one can be used. For example, an acrylic copolymer having a cationic hydrophilic group (hereinafter referred to as hydrophilic) And an epoxyamine adduct resin).

  The hydrophilic acrylic copolymer is obtained by copolymerizing two or more kinds of acrylic monomers having a cationic hydrophilic group (hereinafter referred to as hydrophilic acrylic monomers) or one kind of hydrophilic acrylic monomers. It is obtained by copolymerizing the above and one or more vinyl monomers copolymerizable therewith. Here, the acrylic monomer includes not only acrylic acid and its derivatives but also methacrylic acid and its derivatives.

  Examples of hydrophilic acrylic monomers include amino derivatives of acrylic monomers, hydroxy derivatives of acrylic monomers, and the like.

  Examples of amino derivatives of acrylic monomers include acrylic acid or acrylic acid ester amino derivatives such as dimethylaminoethyl acrylate and diethylaminoethyl acrylate, methacrylic acid or methacrylic acid esters such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate. And salts obtained by quaternizing the amino group in these monomers such as ethyltrimethylammonium acrylate.

  Examples of hydroxy derivatives of acrylic monomers include acrylic acid or acrylic acid esters such as 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, and the like. Examples thereof include hydroxy derivatives, hydroxy derivatives of methacrylic acid or methacrylic acid esters such as 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate and 4-hydroxybutyl methacrylate.

  Examples of vinyl monomers copolymerizable with hydrophilic acrylic monomers include methyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, isobutyl acrylate, benzyl acrylate, cyclohexyl acrylate, and isobonyl acrylate. Cationic hydrophilic, such as acrylic acid or ester of acrylic acid having no cationic hydrophilic group, methyl methacrylate, 2-ethylhexyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, etc. Methacrylic acid or methacrylic acid ester having no group, 2-acryloyloxyethyl hydrogen phthalate, 2-acryloyloxypropyl hydrogen phthalate, 2- (perfluorooctyl) ethyl methacrylate, meta Acrylic acid trifluoromethyl, styrene, N- phenylmaleimide, etc. N- cyclohexyl maleimide.

  The hydrophilic acrylic copolymer comprises 5 to 30% by weight of an amino derivative of acrylic acid or methacrylic acid, 5 to 30% by weight of a hydroxy derivative of acrylic acid or methacrylic acid, and one or more vinyl monomers 40. It is preferable that it is a copolymer containing -90weight%.

  As the epoxyamine adduct resin, those obtained by modifying the epoxy group of the epoxy resin with a primary or secondary amine can be used. The epoxy amine adduct resin is preferably one in which the epoxy group of the epoxy resin is modified with a primary or secondary amine by 30 to 100%.

  Examples of the epoxy resin include bisphenol A type epoxy resin, novolac phenol type epoxy resin, glycidylamine type epoxy resin, dimer acid type epoxy resin and the like. These epoxy resins are available as commercial products. For example, as bisphenol A type epoxy resins, Epicoat 828, Epicoat 834, Epicoat 1001, Epicoat 1004, Epicoat 1007, Epicoat 1009 (all are trade names, oils As the novolak phenol type epoxy resin, Epicoat 152, Epicoat 154 (all of which are trade names, manufactured by Yuka Shell Co., Ltd.) and the like are mentioned. As the glycidylamine type epoxy resin, Epicoat 604 (trade name, manufactured by Yuka Shell Co., Ltd.) and the like are exemplified, and examples of the dimer acid type epoxy resin include Epicoat 872 (trade name, manufactured by Yuka Shell Co., Ltd.).

  The primary amine used for modification of these epoxy resins is not particularly limited, and known ones can be used, for example, monoalkanolamines such as monomethanolamine, monoethanolamine, monoisopropanolamine, dimethylaminoethylamine, Examples thereof include dialkylaminoalkylamines such as diethylaminoethylamine and diethylaminopropylamine. Further, the secondary amine is not particularly limited, and known ones can be used. For example, dialkanolamines such as dimethanolamine, diethanolamine and diisopropanolamine, alkylalkanolamines such as methylethanolamine and methylpropanolamine, And dialkylamines such as (n-butyl) amine.

  By adding a hydrophilic cationic polymer, in the later-described aqueous electrodeposition coating prepared using the resin composition of the present invention, polyimide particles and polyimide added in a solution state and / or a prepolymer thereof as necessary Can be dispersed in acidic water and deposited on the surface of the metal to be coated by an electrodeposition coating method.

  The hydrophilic cationic polymer preferably has at least one of a hydroxyl group and a carboxyl group. By introducing these functional groups into the hydrophilic cationic polymer, the polyimide coated with the thermally reactive groups or the polyimide added as an organic solvent solution or its prepolymer by heating the coating film when used as an aqueous electrodeposition coating. It can cause a crosslinking reaction with the polymer and improve the heat resistance and wear resistance of the coating film.

  The hydrophilic cationic polymer may be used in a solid state, or may be used as a solution dissolved in an organic solvent or a dispersed dispersion (hereinafter collectively referred to as a solution). When the hydrophilic cationic polymer is used as a solution, the hydrophilic cationic polymer is preferably used in the resin composition as a water-soluble organic solvent solution having a solid content concentration of 40 to 80% by weight.

The blending amount of the hydrophilic cationic polymer in the resin composition of the present invention is 15 to 80 parts by weight (15 parts by weight or more and 80 parts by weight or less) in terms of solid content in order to exert the effects of the present invention. There is a need. When the blending amount of the hydrophilic cationic polymer is less than 15 parts by weight, the resin composition of the present invention is hardly dispersed or dissolved in water. Also the amount of the hydrophilic cationic polymer is more than 80 parts by weight, polyimide earthen other later to be added in the form of polyimide particles and organic solvent solution is reduced co析率of the prepolymer, the heat of the coating And insulation cannot be obtained.

  The blending amount of the hydrophilic cationic polymer is more preferably 15 to 75 parts by weight (15 parts by weight or more and 75 parts by weight or less), more preferably 20 to 70 parts by weight (20 parts by weight or more, 70 parts by weight or less).

(C) Organic solvent solution of polyimide or a prepolymer thereof An organic solvent solution of polyimide (hereinafter also simply referred to as polyimide solution) or an organic solvent solution of polyimide prepolymer (hereinafter also simply referred to as polyimide prepolymer solution) includes polyimide particles and It can be compatible with the hydrophilic cationic polymer, whereby the dispersibility of the polyimide particles in water can be improved. Further, when the polyimide Toori others do electrodeposition coating in the electrodeposition coating using the resin composition of the present invention comprising an organic solvent solution of the prepolymer, polyimide or prepolymer of the organic solvent solution, polyimide particles It co-deposits on the electrodeposition coating film together with the hydrophilic cationic polymer and is heated when the coating film is dried or baked. This heating, between the polyimide resin to be added in the form of organic solvent solutions, between the polyimide prepolymer and between the polyimide resin and polyimide prepolymer functional groups such as some have polyimide or a prepolymer thereof and thermally reactive groups A cross-linking reaction occurs between the polyimide particles having the cross-linking and a cross-linking structure is formed in the coating film. Since this crosslinked structure also interacts with the hydrophilic cationic polymer co-deposited on the coating film, the heat resistance, insulation and wear resistance of the coating film are improved.

Therefore, polyimide earthen other in the resin composition of the present invention is adding an organic solvent solution of the prepolymer, which by using an aqueous electrodeposition paint, particularly in heat resistance and abrasion resistance to the treated metal surface An aqueous electrodeposition coating material capable of forming an excellent coating film can be obtained.

  As the polyimide resin added in the form of an organic solvent solution, an organic solvent-soluble polyimide resin is used. As such an organic solvent-soluble polyimide resin, for example, an aromatic tetracarboxylic dianhydride and an aromatic diamine exemplified below are reacted in an equimolar amount in an appropriate organic solvent, and then the imidation ratio is 30 to 30%. Examples thereof include polycondensation polyimide resins obtained by imidization by dehydration ring-closing reaction to 80%.

  Examples of the aromatic tetracarboxylic dianhydride used as the monomer of the organic solvent-soluble polycondensation polyimide resin include 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, etc. Is mentioned. One of these aromatic tetracarboxylic dianhydrides may be used alone, or two or more thereof may be used in combination.

  The aromatic diamine used as the monomer of the organic solvent-soluble polycondensation polyimide resin includes 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, and 1,3-bis (4-aminophenoxy) benzene. 2,2 ′-[4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoro Examples thereof include propane, bis [4- (3-aminophenoxy) phenyl] sulfone, and 2,2-bis [4- (4-aminophenoxy) phenyl] propane. One of these aromatic diamines may be used alone, or two or more thereof may be used in combination.

  In addition, the monomer of the organic solvent-soluble polycondensation polyimide resin is not limited to these, and may be one or two general polyimide resin monomers other than those described above as long as the preferable effects of the present invention are not impaired. More than one species may be used.

  Examples of the organic solvent used in the polyimide solution include polar organic solvents such as N-methylpyrrolidone (abbreviation NMP), N, N-dimethylformamide (abbreviation DMF), and N, N-dimethylacetamide (abbreviation DMAc). Can be mentioned.

  The solid content concentration of the polyimide solution is not particularly limited and can be appropriately selected according to the type of polyimide resin used, but is preferably 5 to 30% by weight in consideration of workability.

  In addition, examples of the polyimide prepolymer added in the form of an organic solvent solution include a prepolymer of a thermally cross-linked polyimide resin. Examples of the prepolymer of the thermally crosslinked polyimide resin include N, N′-m-xylene bismaleimide, N, N′-4,4′-diphenylmethane bismaleimide, N, N′-m-phenylene bismaleimide, N, Examples thereof include bismaleimide compounds such as N′-4,4′-diphenyl ether bismaleimide, and bisnadiimide compounds such as N, N′-m-xylene bisnadiimide and N, N′-4,4′-diphenylmethanebisallyldiimide. It is done. These prepolymers may be used alone or in combination of two or more.

  Examples of the organic solvent used in the polyimide prepolymer solution include polar organic solvents such as N-methylpyrrolidone (abbreviation NMP), N, N-dimethylformamide (abbreviation DMF), and N, N-dimethylacetamide (abbreviation DMAc). Etc.

Change The solid content concentration of the polyimide prepolymer solution is not particularly limited and can be appropriately selected according to the type of prepolymer used. However, considering workability, it is preferably 5 to 80% by weight .

[Water-based electrodeposition paint]
The aqueous electrodeposition coating material of the present invention contains the resin composition of the present invention described above, an acid neutralizing agent, and water.

  Since the resin composition of the present invention contains polyimide particles and a hydrophilic cationic polymer, entanglement, compatibility and wetting between resins such as between polyimide particles, between hydrophilic cationic polymers, and between polyimide particles and hydrophilic cationic polymers. Depending on the nature, it can be dispersed in water and can be made into an electrodeposition paint.

  The use amount of the resin composition of the present invention is preferably 20 to 250 g (20 g or more and 250 g or less), more preferably 50 to 200 g (50 g or more and 200 g or less) with respect to 1 liter of the aqueous electrodeposition coating material. It is.

  In this invention, an acid neutralizing agent is an acidic substance which can neutralize the basic group which components, such as a polyimide particle and a hydrophilic cationic polymer, contained in the resin composition of this invention have. The acid neutralizer is added for the purpose of improving the dispersibility of the resin composition of the present invention in the aqueous electrodeposition coating.

  Examples of the acid neutralizer include organic acids such as lactic acid, acetic acid, formic acid, succinic acid and butyric acid, and inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid. One type of acid neutralizer may be used alone, or two or more types may be used in combination.

  The amount of the acid neutralizer used is preferably 0.2 to 8 g (0.2 g or more and 8 g or less), more preferably 0.5 to 7 g, and further 1 to 6 g based on 1 liter of the aqueous electrodeposition paint. preferable.

Aqueous electrodeposition paint of the present invention, for example, the appropriate amount, as well as polyimide earth floor other as needed by mixing an appropriate amount of an organic solvent solution of the prepolymer resin composition of the polyimide particles or hydrophilic cationic polymers described above Is prepared, and then neutralized by adding an appropriate amount of an acid neutralizing agent to an appropriate amount of the resin composition, and adding or dissolving or dispersing water so that the total amount becomes a desired aqueous electrodeposition coating volume, for example, 1 liter. Can be manufactured by.

  Since the aqueous electrodeposition coating composition of the present invention obtained as described above contains polyimide particles, a coating film having excellent film strength, heat resistance, insulation and edge covering properties is formed on the surface of the metal to be coated. be able to. Moreover, since the resin composition of the present invention contains specific amounts of polyimide particles and hydrophilic cationic polymers, respectively, it is particularly excellent in the heat resistance and insulation of the coating film.

  In addition, since the polyimide particles can be easily dispersed in water without using a polar organic solvent, the amount of the polar organic solvent in the aqueous electrodeposition paint is reduced, or an aqueous electrodeposition paint containing no polar organic solvent is used. Can be realized. Therefore, the water-based electrodeposition paint of the present invention can form a coating film excellent in moisture resistance and edge covering properties, and has excellent characteristics in terms of safety and environment.

Further, as the resin composition to be added to the aqueous electrodeposition paint of the present invention, by using those containing one or organic solvent solution Neu deviation of an organic solvent solution or polyimide prepolymer polyimide resin, the heat resistance of the coating film, Insulation and wear resistance can be improved. Furthermore, heat resistance, insulation, and abrasion resistance can be further improved by introducing thermally reactive groups such as amino groups and epoxy groups into the polyimide particles. Various functions and properties can be imparted to the coating film by adjusting the particle size of the polyimide particles.

  The aqueous electrodeposition paint of the present invention is suitably used for electrodeposition coating on various metal surfaces such as copper, copper alloys, nickel, and the like.

  Electrodeposition coating of a metal surface using the aqueous electrodeposition paint of the present invention can be carried out as follows in the same manner as in the conventional method except that the aqueous electrodeposition paint of the present invention is used.

  First, a degreasing treatment is performed on an object to be coated which is made of at least one or two or more kinds of metals. The degreasing treatment is performed according to a known method, for example, by supplying an alkaline aqueous solution to the surface of the object to be coated. The supply of the alkaline aqueous solution is performed, for example, by spraying the alkaline aqueous solution on the surface of the object to be coated or immersing the object to be coated in the alkaline aqueous solution. As the alkali, those commonly used for metal degreasing can be used, and examples include alkali metal phosphates such as sodium phosphate and potassium phosphate. The pH of the alkaline aqueous solution is appropriately selected according to the type of metal to be treated and the degree of contamination of the object to be coated, but is preferably about pH 8 to 10. The alkali concentration in the aqueous alkali solution is appropriately determined according to the type of alkali used and the desired pH value. For example, when the object to be coated is immersed in an alkaline aqueous solution, the degreasing treatment is performed under the condition that the temperature of the alkaline aqueous solution is about 20 to 50 ° C. and is completed in about 1 to 5 minutes. The object to be coated that has been subjected to the degreasing treatment is washed with water and subjected to the next neutralization step.

  The neutralization treatment in the neutralization step is performed according to a known method, for example, by supplying an acid aqueous solution to the surface of the object to be coated. The acid aqueous solution is supplied by spraying the acid aqueous solution onto the surface of the object to be coated, immersing the object to be coated in the acid solution, and the like in the same manner as supplying the aqueous alkali solution in the degreasing treatment. As the acid, those commonly used for neutralization of alkali can be used, and examples thereof include sulfuric acid, nitric acid, and phosphoric acid. The acid concentration in the acid aqueous solution is appropriately selected according to the alkali concentration in the alkaline aqueous solution used for the degreasing treatment, the type of metal to be treated, and the like. For example, when the object to be coated is immersed in an acid aqueous solution, the neutralization treatment is performed under the condition that the temperature of the acid aqueous solution is about 20 to 30 ° C., and is completed in about 15 to 60 seconds (1 minute). To do. The object to be coated that has been subjected to the neutralization treatment is washed with water and subjected to the next electrodeposition coating process.

  In the electrodeposition coating process, the object to be coated is electrodeposited with the aqueous electrodeposition coating of the present invention. The electrodeposition coating is carried out according to a known method, for example, by immersing the object to be coated completely or partially in an energization tank filled with the aqueous electrodeposition paint of the present invention and energizing in this state. The electrodeposition coating conditions are not particularly limited, depending on various conditions such as the composition of the aqueous electrodeposition coating of the present invention, the type of metal to be coated, the size and shape of the current-carrying tank, and the use of the resulting coating. The electrode temperature is preferably about 10 to 50 ° C., the applied voltage is about 10 to 250 V, and the voltage application time is about 1 to 10 minutes. The object to be coated is taken out from the energization tank, washed with water, and subjected to the next drying process.

  In the drying step, the object to be coated after washing with water is heated and dried. The drying conditions are not particularly limited and can be appropriately selected from a wide range, but are preferably about 10 to 30 minutes at a temperature of about 50 to 130 ° C. Next, the coating film formed on the surface of the object to be coated is baked and fixed on the surface of the object to be coated. The baking conditions are appropriately selected according to the type of metal to be treated, the composition of the aqueous electrodeposition paint of the present invention used in the electrodeposition coating, and preferably at a temperature of about 120 to 260 ° C., It is about 10 minutes to 1 hour. As described above, an article having a coating film formed on the metal surface is obtained.

Examples of the use of the aqueous electrodeposition coating composition of the present invention include the following.
(1) Heat-resistant insulation coating for magnet wires Insulating coatings for coils that change electrical energy into magnetic energy such as motors and transformers are required to have excellent heat resistance and adhesion. For this reason, when forming an insulating film for a coil, it is necessary to perform multilayer coating by applying about 10 layers of polyimide varnish, polyamideimide varnish, and the like. On the other hand, the water-based electrodeposition paint of the present invention can form an insulating film having excellent heat resistance by a single coating process. In addition, since the film formation method is based on electrophoresis, the formed insulating coating is excellent in adhesion to the coil material. Therefore, simplification of the manufacturing process and mass production are possible by using the water-based electrodeposition paint of the present invention.

(2) Insulating paint for circuit boards In the field of electronic equipment, along with improvements in operating speed and integration of integrated circuit (abbreviated IC) chips, hard disk (abbreviated HD) drives, miniaturization and complexity of circuit patterns, etc. Therefore, there is a demand for a heat-resistant insulating coating technique that can form an insulating film having necessary heat resistance and insulation at a required portion. In addition, the insulating film formed on the circuit board is required to have no dimensional change due to humidity as the durability of the substrate material.

  Since the coating film formed by the aqueous electrodeposition coating of the present invention has excellent heat resistance and insulation, it is possible to reduce the size of the insulating film necessary to achieve the desired heat resistance and insulation, It is possible to form an insulating film only at a desired portion corresponding to the circuit pattern. In addition, the aqueous electrodeposition coating composition of the present invention can have a composition containing almost no polar organic solvent such as DMF or NMP, which is a major factor of dimensional change due to humidity, so that the substrate insulation is hardly affected by humidity. Film formation is possible. Therefore, by using the aqueous electrodeposition paint of the present invention, a new construction method such as batch processing of large area parts with a fine pattern can be realized.

(3) Heat-resistant and abrasion-resistant paint for sliding parts Heat-resistant and abrasion-resistant coatings are used for sliding parts used as moving parts in motors and home appliances in order to improve heat resistance and wear resistance. Is given. As this heat-resistant and wear-resistant coating, conventional heat-resistant and wear-resistant coating (coating) has been carried out by spraying methods such as fluorine resin and polyimide varnish, but conventional coatings have become smaller and thinner and thinner. Technology is no longer able to handle it. In addition, conventional heat-resistant and wear-resistant coatings require a surface roughening process such as sandblasting as a pretreatment for coating in order to improve the adhesion between the parts and the coating film. Is difficult.

  Since the aqueous electrodeposition coating material of the present invention is a coating technique based on electrophoresis, it is possible to uniformly coat articles having complicated shapes. The aqueous electrodeposition coating composition of the present invention can form a coating film having excellent wear resistance, and can further improve the wear resistance by adding fluororesin particles. Furthermore, since the process of roughening the surface of the parts before painting is not required, mass production of the miniaturized parts becomes possible.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
In addition, each physical property value in a present Example was each measured as follows.

(1) Glass transition point and melting point The glass transition point and melting point were determined by a differential scanning calorimeter (trade name: DSC220CV, manufactured by Seiko Instruments Inc.). The measurement was performed under the conditions of a temperature rising rate of 20 ° C./min and a nitrogen inflow of 50 mL / min in a nitrogen atmosphere. The temperature at the top of the endothermic peak of the obtained DSC curve was taken as the melting point. In addition, the endothermic peak corresponding to the glass transition of the DSC curve was drawn at a point where the gradient is maximum with respect to the straight line extending from the high temperature side base line to the low temperature side and the curve from the peak rising portion to the apex. The temperature at the intersection with the tangent was taken as the glass transition point.

(2) Thermal decomposition temperature The thermal decomposition temperature was calculated | required with the thermogravimetric analyzer (brand name: TG / DTA320V, Seiko Instruments Inc. make). The measurement was performed under a nitrogen atmosphere under a temperature rising rate of 10 ° C./min and a nitrogen inflow rate of 200 mL / min. In the obtained TGA curve, the temperature at the intersection of a straight line parallel to the horizontal axis passing through the mass before the start of heating and a tangent drawn at a point where the gradient between the bending points is maximized was defined as the thermal decomposition temperature.

(3) Average particle diameter and coefficient of variation The average particle diameter and coefficient of variation of the polyimide particles were determined as follows.

First, polyimide particles are observed with a scanning electron microscope (SEM), 100 arbitrary particles are selected from the SEM photograph, and the average of these particle diameters is determined according to the following formula (1). It was.
Average particle diameter X = (1 / n) ΣXi (1)
(In formula (1), n represents the number of measurement data, and Xi represents the measurement data value.)

Next, based on the obtained average particle diameter X, the standard deviation S was determined according to the following mathematical formulas (2) and (3), and the variation coefficient C was further determined according to the following mathematical formula (4).
Variance S ² = [1 / (n−1)] (ΣXi ² −X · ΣXi) (2)
Standard deviation S = (S ² ) ^1/2 (3)
Coefficient of variation C = (S / X) × 100 (4)

(4) Logarithmic Viscosity and Viscosity Logarithmic viscosity and viscosity were measured at a temperature of 25 ° C. using a viscosity measuring device (trade name: B8H type viscometer, manufactured by Tokimec Co., Ltd.).

  In Examples and Comparative Examples, polyimide particles A-1 and A-2, polyimide prepolymer solution B-1, polyimide solution B-2, and hydrophilic cationic polymers C-1 and C-2 shown below were used. The structure of each resin shown below was confirmed by FT-IR.

(Production Example 1) Production of polyimide particles A-1 Polyimide particles A-1 were produced as follows.

  A solution in which 7.5 g (0.06 mol) of 2,4,6-triaminopyrimidine was dissolved in 150 mL of methanol and a solution in which 48 g (0.24 mol) of 4,4′-diaminophenyl ether was dissolved in 800 mL of acetone were obtained. After the addition, this mixed solution was added to a solution prepared by dissolving 96.67 g (0.3 mol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride in 750 mL of acetone, and irradiated with ultrasonic waves. The reaction was continued for 30 minutes. SC-650N (trade name, output 600 W, transmission frequency 28 kHz ± 10%) manufactured by SMT Co., Ltd. was used as the ultrasonic generator. After completion of the reaction, the polyamic acid particles produced as a precipitate were isolated with a centrifuge and washed repeatedly with xylene.

  100 g of the obtained polyamic acid particles were dispersed in 500 mL of n-dodecane, and then refluxed for 4 hours while stirring with a magnetic stirrer. At this time, the reaction proceeded while condensate water by-produced with imidization was distilled out of the reaction system by azeotropy with n-dodecane. After completion of the reaction, the produced polyimide particles were isolated by centrifugation and purified by washing with a reaction solvent and acetone.

  As described above, polyimide particles A-1 having an amino group on the particle surface were produced. The obtained polyimide particles A-1 had an average particle size of 1094 nm (1.094 μm), a coefficient of variation of 5.8%, a glass transition point of 320 ° C., and a thermal decomposition temperature of 542 ° C.

(Production Example 2) Production of polyimide particles A-2 Polyimide particles A-2 were produced as follows.

  3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA) 0.24 mol, 1,4-bis (4-aminophenoxy) benzene (TPE-Q) 0.12 mol, bis 0.14 mol of (4- (3-aminophenoxy) phenyl) sulfone (MAPS-M) was stirred in 1200 mL of N, N-dimethylformamide (DMF) at room temperature under a nitrogen gas atmosphere for 24 hours. By reacting, a polyamic acid which is a polyimide prepolymer was obtained in a solution state.

  240 mL of toluene was added to 1200 mL of the obtained polyamic acid solution, and the mixture was refluxed for reaction. A 2000 mL separable flask was used as the reaction vessel, a test tube was attached between the reflux condenser and the separable flask, and the vertical stirring rod was rotated at a speed of 360 rpm (360 rpm) for reaction while stirring. I let you. At this time, water produced as a by-product with the imidization reaction was trapped in a water detection tube outside the reaction system by azeotropy with toluene, and the reaction was performed while returning toluene into the flask by overflow. The completion of the reaction was judged by the presence or absence of water as a by-product. In this production example, the production of water was completed in about 3 hours from the start of reflux. Refluxing was continued for about 1 hour after the generation of water was completed, and the total refluxing was performed for about 4 hours. After completion of the reaction, the precipitated polyimide particles were separated by a centrifugal separator and purified by washing with toluene, methanol and acetone as reaction solvents.

  As described above, polyimide particles A-2 were produced. The obtained polyimide particles A-2 had an average particle size of 5880 nm (5.880 μm), a coefficient of variation of 17.3%, a melting point of 372 ° C., a glass transition point of 246 ° C., and a thermal decomposition temperature of 541 ° C. .

Production Example 3 Production of Polyimide Prepolymer Solution B-1 N, N′-4,4′-diphenylmethane bismaleimide was dissolved in N-methylpyrrolidone, and a prepolymer of a thermally crosslinked polyimide resin having a solid content concentration of 75% by weight. A solution was prepared, and this was designated as polyimide prepolymer solution B-1.

(Manufacture example 4) Manufacture of polyimide solution B-2 As polyimide solution B-2, the organic solvent solution of polycondensation polyimide resin was manufactured as follows.

  To a four-necked flask equipped with a Dimroth reflux tube, add 0.5 mol of 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride and 0.5 mol of 4,4′-diaminodiphenyl ether. , Diluted with N-methylpyrrolidone to a non-volatile content of 20% by weight and reacted at 25 ° C. with stirring for 24 hours to synthesize polyamic acid. To the resulting solution containing polyamic acid, 30 g of toluene was added, refluxed at 140 ° C. for 4 hours, and water generated by the dehydration reaction was removed from the reaction system by azeotropy with toluene, and a dehydration cyclization reaction was performed. A brown transparent polyimide solution B-2 having a solid content concentration of 20% by weight and a logarithmic viscosity of 0.6 was obtained.

(Production Example 5) Production of hydrophilic cationic polymer C-1 The hydrophilic cationic polymer C-1 was produced as follows.

  First, 25 g of N-phenylmaleimide, 20 g of methyl methacrylate, 30 g of 2-hydroxyethyl acrylate, 15 g of n-butyl acrylate, 25 g of dimethylaminoethyl methacrylate, 25 g of styrene and 1 g of benzoin peroxide as a polymerization initiator were mixed. A monomer mixture was prepared. Next, 60 g of diethylene glycol monoisopropyl ether was placed in a four-necked flask equipped with a Dimroth reflux tube and heated under reflux. Then, a dropping funnel was attached to the four-necked flask, and the above-mentioned monomer mixture was stirred with a motor. The divided ones were dropped from a dropping funnel at 10 minute intervals and reacted at a temperature of 75 ° C. for 5 hours. Thereafter, 0.1 g of benzoin peroxide was added, and the mixture was refluxed for about 1 hour until the monomer odor disappeared. The solid content concentration was 70% by weight, the viscosity was 20 Pa · s (20,000 cps) at 25 ° C. Hydrophilic cationic polymer C-1 was obtained as a resin solution. Here, MEQ is an abbreviation for mg equivalent, and is the mg equivalent of the neutralizing agent (acid) per 100 g of the solid content of the solution.

(Production Example 6) Production of hydrophilic cationic polymer C-2 The hydrophilic cationic polymer C-2 was produced as follows.

  In a four-necked flask equipped with a Dimroth reflux tube, 500 g of an epoxy resin (trade name: Epicoat 1001, manufactured by Yuka Shell) and 300 g of propylene glycol monomethyl ether were dissolved. A dropping funnel was attached to the aforementioned four-necked flask, and the liquid temperature was kept at 90 ° C., and 180 g of diethanolamine was dropped from the dropping funnel over 60 minutes while stirring with a motor. After completion of the dropwise addition, the mixture was heated at a liquid temperature of 120 ° C. for 90 minutes, the solid content concentration was 70% by weight, the viscosity was 13 Pa · s (13,000 cps) at 25 ° C., and the hydrophilic cationic polymer C- 2 was obtained.

[Example]
(1) Preparation of water-based electrodeposition paint (Examples 1-8)
In Examples 1 to 8, water-based electrodeposition paints were produced as follows.

  As the component A, a polyimide prepolymer solution shown in Table 1 or a polyimide solution and a hydrophilic cationic polymer were used at a ratio shown in Table 1, and the mixture was mixed at a liquid temperature of 50 ° C. for 2 hours. Next, the polyimide particles shown in Table 1 as component B were added at the rate shown in Table 1, glass beads were added to this solution at the rate shown in Table 1, and the number of revolutions of the disk was set at 3000 rpm, and 1 in a bead mill. The resin composition of this invention was obtained by mixing for a time.

  Next, lactic acid was added as an acid neutralizer in the ratio shown in Table 1, and the mixture was neutralized by mixing at room temperature for 30 minutes. To this solution, pure water was added over 2 hours so that the total amount was 1 liter, and the resin composition was dispersed in water. As described above, the aqueous electrodeposition paints of Examples 1 to 8 satisfying all the requirements of the present invention were produced.

(Comparative Example 1)
As the resin composition, a polyimide prepolymer solution of component A shown in Table 1 and a hydrophilic cationic polymer mixed at a ratio shown in Table 1 at a liquid temperature of 50 ° C. for 2 hours, except that component B is not used Produced the water-based electrodeposition paint of Comparative Example 1 in the same manner as in Examples 1-8. That is, Comparative Example 1 does not use polyimide particles.

(Comparative Example 2)
As the resin composition, except that the polyimide solution of component A shown in Table 1 and the hydrophilic cationic polymer were mixed at a liquid temperature of 50 ° C. for 2 hours at the ratio shown in Table 1, and component B was not used, The aqueous electrodeposition coating material of Comparative Example 2 was produced in the same manner as in Examples 1-8. That is, Comparative Example 2 does not use polyimide particles.

  Table 1 shows the amount of each component, mixing conditions, and water conversion conditions in each example and comparative example. Table 1 shows the polar organic solvent concentration, pH of the aqueous electrodeposition coating material, electrical conductivity (measurement temperature 25 ° C.), and appearance, which are contained in the prepared water electrodeposition coating material. In addition, the compounding quantity of each component shown in Table 1 is the gram number (solid content weight) contained in 1 liter of aqueous electrodeposition coating materials. Moreover, about the component which is not used, it describes as "-".

  From Table 1, it can be seen that the concentration of the polar organic solvent in the aqueous electrodeposition coatings of the present invention of Examples 1 to 8 is as low as 1.50%, which is high in safety and has little influence on the environment. .

(2) Electrodeposition coating experiment In order to evaluate the properties of the coating film, electrodeposition coating was performed on the test piece as follows.

  1 liter of the aqueous electrodeposition paint obtained in Examples 1 to 8 and Comparative Examples 1 and 2 was placed in a current-carrying tank, the liquid temperature was kept at 25 ° C., and electrodeposition coating was performed. A carbon plate was used as the anode, and a copper plate (dimension 50 × 50 mm) as a test piece was used as the cathode. A specific process is shown in FIG.

  First, the copper plate which is a test piece in the step (a) was degreased for 5 minutes using a weak alkaline aqueous solution (pH 8) having a liquid temperature of 50 ° C., and washed with water in the step (b). Next, in step (c), neutralization was performed for 1 minute at room temperature using nitric acid having a concentration of 1%, and the mixture was washed with water in step (d).

  Next, in step (e), the substrate was washed with ion-exchanged water. In step (f), a voltage of 100 V was applied between the electrodes for 1 minute to perform electrodeposition coating. Subsequently, it was washed with water in the step (g), dried at a temperature of 100 ° C. for 15 minutes in the step (h), and finally baked at a temperature of 180 ° C. for 30 minutes in the step (i).

About the test piece coated as described above (hereinafter referred to as a coated sample plate), film thickness (JIS K5400 3.5), appearance (visual observation), pencil hardness (JIS K5400 8.4.2), grid pattern Peel test (JIS K5400 8.5.1), glass transition point (DSC (
Differential Scanning Calorimetry (measurement)), volume resistivity, heat loss (TG-DTA (thermogravimetric differential thermal analysis) measurement in nitrogen atmosphere) and heat resistance test (insulation breakdown voltage measurement before and after heating at 220 ° C. for 100 hours) were evaluated. In addition, DSC measurement and TG-DTA measurement were respectively performed using the above-mentioned differential scanning calorimetry analyzer and thermogravimetric analyzer.

  Moreover, the moisture absorption rate was calculated | required as follows about the coating test board. First, a moisture absorption test was performed in which the painted test plate was left in a sealed container at a temperature of 85 ° C. and a relative humidity of 85% (85RH%) for 1000 hours. A value (W2-W1) obtained by subtracting the weight W1 of the coating test plate before the moisture absorption test from the weight W2 of the coating test plate after the moisture absorption test is obtained as the moisture absorption amount ΔW, and the weight W1 of the coating test plate before the moisture absorption test of this value The weight percentage (ΔW / W1 × 100) with respect to was determined as the moisture absorption rate (%).

Moreover, it carried out similarly to the coating test board, the electrodeposition coating was performed with respect to the copper flat wire (width 1.5mm x thickness 0.1mm, length 300mm), and it used for the edge covering test. In addition, the electrodeposition coating to the flat electric wire was performed by setting the applied voltage at the time of electrodeposition coating so that the film thickness D1 of the flat portion 11 shown in FIG. The cross section of the coated flat electric wire 10 was observed, and the film thickness D2 of the edge portion 12 shown in FIG. 2 was measured.
The above evaluation results are shown in Table 2.

  From Table 2, about the film thickness, all of the paints of Examples 1 to 8 and Comparative Examples 1 and 2 were in the range of 8 to 15 μm. Moreover, the smooth external appearance was obtained in any of Examples 1-8 and Comparative Examples 1 and 2. In the pencil hardness test, all of the paints of Examples 1 to 8 and Comparative Examples 1 and 2 were 4H. In the cross-cut peel test, the paints of Examples 1 to 8 and Comparative Examples 1 and 2 were all 100/100.

  The glass transition points were 275-284 ° C. for Examples 1-4 and 240-255 ° C. for Examples 5-8. The glass transition point of the paint of Comparative Example 1 was 240 ° C., and the glass transition point of the paint of Comparative Example 2 was 210 ° C. It was included in the paint of Examples 1-4 that the coating film formed with the coating material of Examples 1-4 showed the glass transition point higher than the coating film formed with the coating material of Examples 5-8. This is presumably because a more rigid cross-linked structure was formed as a result of the amino group in the polyimide particles being subjected to a cross-linking reaction during the heat treatment. Moreover, about Examples 5-8, although the glass transition point was a little inferior compared with Examples 1-4, it became a high glass transition point compared with the comparative example 2. This is presumed that the paints of Examples 5 to 8 contained a large amount of polyimide particles, so that a glass transition point higher than that of the paint of Comparative Example 2 could be obtained.

The volume resistance value of each of the paints of Examples 1 to 8 and Comparative Examples 1 and 2 exceeded 1 × 10 ¹⁶ Ω · cm.

  About heat loss, it becomes 2% or less in Examples 1-4, 2.25-2.5% in Examples 5-8, 3.50% in Comparative Example 1 and 5.30% in Comparative Example 2 Excellent value was shown. This is presumed to be due to the influence of the resin composition and the crosslinked structure formed by the coating film in the aqueous electrodeposition paint of the present invention.

  In the heat resistance test, none of the paints of Examples 1 to 8 and Comparative Examples 1 and 2 showed any change before and after heating at 220 ° C., and showed a sufficient insulating property of 1.1 to 1.5 kV.

  Moreover, about the moisture absorption rate, it became a very low result in Examples 1-8. This is considered to be due to the low concentration of the polar organic solvent in the paints of Examples 1 to 8.

  On the other hand, in the edge covering test, in the coating materials of Examples 1 to 8, the difference between the film thickness D1 of the flat portion and the film thickness D2 of the edge portion is smaller than that of Comparative Examples 1 and 2, and the edge covering property is excellent. As a result. On the other hand, it was found that the edge covering properties were considerably inferior in Examples 1 and 2 compared with Examples 1-8. This is presumably because Comparative Example 1 and 2 did not contain polyimide particles, and the amount of polar organic solvent contained was large, and therefore the coating film flowed vigorously due to the solvent contained in the coating film. Especially in Comparative Example 2, since the temperature at which the thermal crosslinking reaction occurs in the coating film is higher than in Examples 1 to 8, the coating film flows before the coating film is cured by the thermal crosslinking reaction, and the edge portion is It is considered exposed.

  Moreover, it turned out that the film thickness D2 of an edge part is maintained to the same extent as the film thickness D1 of a flat part especially in Examples 5-8 among Examples 1-8. This is considered to be because the average particle diameter of the polyimide particles contained in the paints of Examples 5 to 8 is larger than the polyimide particles contained in the paints of Examples 1 to 4 and the fluidity of the coating film is suppressed. . On the other hand, in Examples 1 to 4, the film thickness D1 of the flat portion was 10 μm, whereas the film thickness D2 of the edge portion was slightly small as 6 to 7 μm. This is presumably because the average particle diameter of the polyimide particles is slightly smaller than the paints of Examples 5 to 8, and the contribution to the fluidity of the coating film is slightly smaller.

  As described above, the aqueous electrodeposition coating composition of the present invention using the resin composition of the present invention is a coating excellent in all of heat resistance, insulation, moisture resistance and edge covering properties on the metal surface to be coated. It can be seen that the film can be formed and has excellent characteristics in terms of safety and environment.

It is a process figure of the electrodeposition coating in an electrodeposition coating test. It is sectional drawing which shows the structure of the coated flat electric wire 10 with which it uses for an edge covering test.

Explanation of symbols

10 flat wire 11 flat part 12 edge part 13 coating film

Claims (5)

A resin composition comprising polyimide particles, a polyimide organic solvent solution or a polyimide prepolymer organic solvent solution, and a hydrophilic cationic polymer , wherein the polyimide particles in the resin composition and the hydrophilic 5 to 80 parts by weight of the polyimide particles and 15 to 15 parts of the hydrophilic cationic polymer so that the total amount of the cationic cationic polymer and the polyimide or the prepolymer of the polyimide is 100 parts by weight in terms of solid content. 80 parts by weight, 5 to 80 parts by weight of the polyimide or the polyimide prepolymer,
Resin composition, wherein the average particle size of the poly Lee bromide particles is 1 to 6 m.   The resin composition according to claim 1, wherein the polyimide particles have a thermally reactive group.   The resin composition according to claim 2, wherein the heat-reactive group is at least one of an amino group and an epoxy group.   An aqueous electrodeposition paint comprising the resin composition according to any one of claims 1 to 3, an acid neutralizer, and water.   The aqueous electrodeposition coating composition according to claim 4, wherein the acid neutralizing agent is at least one of an organic acid and an inorganic acid.

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