JP2012036314A - Resin composition for electrodeposition coating, water-based electrodeposition coating, coating method, and coated article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for electrodeposition coating giving thermal conductivity, heat dissipation and insulation property even to a complicated and complex shape, a water-based electrodeposition coating, a coating method and a coated article thereof.SOLUTION: The resin composition comprises ceramic fine particles having thermal conductivity and insulation property and a hydrophilic resin containing an acidic group or a hydrophilic resin containing a basic group. In the resin composition for electrodeposition coating, 5-50 wt.% of the ceramic fine particles having thermal conductivity and insulation property and 50-95 wt.% of the hydrophilic resin containing the acidic group or the hydrophilic resin containing the basic group are formulated relative to the whole weight of the resin composition. In the water-based electrodeposition coating, the resin composition is dispersed in water containing a basic neutralizing agent or an acidic neutralizing agent and coating is possible on a solid having electric conductivity. In the method and the coated article, electrodeposition coating is performed using the coating.

Description

  TECHNICAL FIELD The present invention relates to a resin composition for electrodeposition paints comprising ceramic fine particles having thermal conductivity and insulating properties and a hydrophilic resin containing an acidic group or a basic group, an aqueous electrodeposition paint, a coating method, and a coated product thereof. . More specifically, the present invention relates to a resin composition for electrodeposition paints that imparts heat dissipation and insulation to an object to be coated, an aqueous electrodeposition paint, a coating method, and a coated object thereof.

Conventionally, as a method for imparting heat dissipation to an object to be coated, a method of forming a fin shape with a large surface area by subjecting an aluminum light alloy to alumite treatment (for example, Patent Document 1), SnO ₂ —Sb ₂ O in a vehicle _There is a method of applying a paint in which ₅ type semiconductor particles are dispersed (for example, Patent Document 2).

JP 2004-43612 A JP 2001-230580 A

  However, the former method is limited in the width of material selection and the space occupied by parts. The latter method is expensive because specific semiconductor particles are used, and is not applicable to complicated shapes because it is used for spray coating. Also, since semiconductor particles are blended, there is no electrical insulation and it is difficult to apply to electrical and electronic parts.

  Electrodeposition paints can be co-deposited with various materials as fillers to improve various properties depending on the application, and can be applied to complicated and complicated shapes. Electrodeposition paints that impart insulating properties are not on the market.

  An object of the present invention is to provide a resin composition for an electrodeposition coating, an aqueous electrodeposition coating, a coating method and a coating method capable of imparting thermal conductivity, heat dissipation and insulation even on a complicated and complicatedly painted surface It is to provide a painted product.

  The present invention relates to a resin composition comprising ceramic fine particles having thermal conductivity and insulating properties and a hydrophilic resin containing an acidic group, wherein the thermal conductivity and insulation with respect to the total weight of the resin composition. It is a resin composition for electrodeposition coatings containing 5 to 50% by weight of ceramic fine particles having a property and 50 to 95% by weight of a hydrophilic resin containing the acidic group.

  The present invention is also a resin composition comprising ceramic fine particles having thermal conductivity and insulating properties and a hydrophilic resin containing a basic group, wherein the thermal conductivity is relative to the total weight of the resin composition. And 5 to 50% by weight of ceramic fine particles having insulating properties and 50 to 95% by weight of the hydrophilic resin containing the basic group.

  Further, the present invention is characterized in that the above-mentioned resin composition for electrodeposition paint containing a hydrophilic resin containing an acidic group is dispersed in water containing a basic neutralizing agent. It is a water-based electrodeposition paint that can be applied to a solid.

  Further, the present invention provides an electrical conductivity characterized by dispersing the above resin composition for electrodeposition paint containing a hydrophilic resin containing a basic group in water containing an acidic neutralizing agent. It is a water-based electrodeposition paint that can be applied to a solid.

  The present invention is also a method for electrodeposition coating on an electrically conductive solid using the aqueous electrodeposition coating described above.

  Further, the present invention is a coated product in which a solid having electrical conductivity is electrodeposited by the above-described electrodeposition coating method.

  Furthermore, the present invention is characterized in that the electrically conductive solid to which the above-described electrodeposition coating method is applied is a circuit board or a reflector of an optical component.

  According to the present invention, since the hydrophilic resin contains an acidic group or a basic group, it can be dispersed in water containing a basic neutralizing agent or an acidic neutralizing agent. That is, in the present invention, the hydrophilic resin refers to a resin that can be dispersed or dissolved in water when an acidic group or a basic group is neutralized with a basic neutralizer or an acidic neutralizer. In addition, ceramic fine particles having thermal conductivity and insulating properties can be dispersed in hydrophilic resins containing acidic groups or hydrophilic resins containing basic groups, and these are uniformly impregnated and wetted together. A dispersed aqueous electrodeposition coating can be obtained. Ceramic fine particles having thermal conductivity and insulating properties after coating impart thermal conductivity, heat dissipation and insulating properties to the object to be coated, and also hydrophilic resins containing acidic groups or hydrophilic resins containing basic groups After heat drying, the insulating property can be imparted to the object to be coated. It is possible to impart heat dissipation and electrical insulation to all solids having electrical conductivity, such as metals, semiconductors, and electrically conductive ceramics that do not inherently have thermal conductivity.

Since the resin composition for electrodeposition paints of the present invention can be dispersed in water, it has excellent safety and environmental characteristics by reducing the amount of organic solvent used.
In the present invention, an organic-inorganic hybrid coating film having a heat dissipation characteristic similar to that of anodized can be easily applied onto a metal with low heat conductivity, and the excellent uniform coating property makes it possible to freely form parts. It greatly contributes to improvement of the degree. Moreover, since it is based on an organic coating film, it also has insulating properties.

  According to the present invention, since the hydrophilic resin containing an acidic group is dispersed in water containing a basic neutralizing agent, the resin composition containing ceramic fine particles having thermal conductivity and insulating properties is dispersed in water. It becomes a water-based electrodeposition paint. This water-based electrodeposition paint can be electrodeposited on a solid having electrical conductivity, and can impart thermal conductivity, heat dissipation and electrical insulation to the coated object. In addition, since water-based electrodeposition paint is used, it has excellent characteristics in terms of safety and environment.

  According to the present invention, since the hydrophilic resin containing a basic group is dispersed in water containing an acidic neutralizer, the resin composition containing ceramic fine particles having thermal conductivity and insulating properties is dispersed in water. It becomes a water-based electrodeposition paint. This water-based electrodeposition paint can be electrodeposited on a solid having electrical conductivity, and the coated material has thermal conductivity, heat dissipation and electrical insulation. In addition, since water-based electrodeposition paint is used, it has excellent characteristics in terms of safety and environment.

  According to the present invention, the method of electrodeposition coating on a solid having electrical conductivity is such that the ceramic fine particles having thermal conductivity and insulation are 5 to 50% by weight based on the total weight of the resin composition, Since an aqueous electrodeposition paint in which a resin composition for electrodeposition paint containing 50 to 95% by weight of a hydrophilic resin containing an acidic group or a hydrophilic resin containing a basic group is dispersed in water is used, painting Thermal conductivity, heat dissipation, and electrical insulation can be imparted to the finished product.

  According to the present invention, since the water-based electrodeposition paint contains ceramic fine particles having thermal conductivity and insulation, the electrodeposited coating has thermal conductivity, heat dissipation and electrical insulation.

According to the present invention, since the solid having electrical conductivity is a circuit board or a reflection plate of an optical component, the effect of the electrodeposition paint of the present invention can be suitably exhibited. The heat radiation insulation electrodeposition coating on the circuit board is
The substrate material does not undergo a chemical change, and it is possible to selectively and uniformly dissipate a heat-dissipating insulating coating only on a necessary portion. The reflection plate of the optical component can be given heat dissipation, heat conductivity and insulation without losing luster by selecting a particle size of fine powder having appropriate heat dissipation.

It is a flowchart of the electrodeposition coating method of one Embodiment in this invention.

(Resin composition for paint)
In the present invention, the ceramic fine particles having thermal conductivity and insulating properties are solid solid materials having hard properties, nonflammability and non-corrosive properties as well as thermal conductivity and insulating properties. By blending these in the electrodeposition coating, it is possible to impart thermal conductivity, heat dissipation and insulation to the coating film.

  The thermal conductivity of the ceramic fine particles is usually 1 to 2,000 W / m · K, preferably 5 to 1,000 W / m · K, and particularly preferably 10 to 500 W / m · K. When it is 1 to 2,000 W / m · K, heat conductivity and heat dissipation can be exhibited, and when it is 5 to 1,000 W / m · K, heat conductivity and heat dissipation are further improved, and 10 to 500 W / m When m · K, the thermal conductivity and heat dissipation are particularly good. Specific examples of the ceramic fine particles include silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, beryllium oxide, magnesium oxide, zirconium oxide, boron nitride, and mixtures thereof. However, even if it is material other than these, if it has heat conductivity and insulation, it will not specifically limit. Considering practical applicability in particular, aluminum oxide, magnesium oxide, zirconium oxide and boron nitride are available from a viewpoint of being relatively inexpensively available, high in thermal conductivity, chemically stable and harmless. Is preferred.

  The shape of the ceramic fine particles can be in various forms such as spherical, fibrous, flaky, fibrous, and needle-like, and even if the crystalline form of the substance itself is used, it is a grade that is commercially available after grinding and classification May be used. Among these, the spherical shape is preferable from the viewpoint of dispersibility.

  As the ceramic fine particles having heat conductivity and insulating properties, it is preferable to use a particulate material from the viewpoint of enhancing the heat transfer efficiency between the coating film and the atmospheric gas. When ceramic fine particles are blended, the smoothness of the surface shape is disturbed to some extent, and the surface area is increased. That is, the heat exchange area is expanded, and at this time, turbulent flow is further generated on the surface of the coating film, so that the heat exchange efficiency can be improved. If the particle size is too small, the dispersibility is high and the surface of the coating film becomes smooth, and the heat exchange efficiency may not be sufficiently improved. For this reason, the particle diameter of the ceramic fine particles is preferably 5 nm or more, more preferably 10 nm or more, and particularly preferably 20 nm or more. On the other hand, if it is too large, the smoothness is disturbed and the gloss is lowered, and the particles may be detached after the coating film is formed. For this reason, the particle diameter of the ceramic fine particles is preferably 20 μm or less, more preferably 10 μm or less, and particularly preferably 8 μm or less. In the present invention, the particle diameter means the average diameter of the ceramic fine particles used, and can be measured by an ultracentrifugal automatic particle size distribution analyzer (for example, CAPA-700 manufactured by Horiba, Ltd.).

  A hydrophilic resin containing an acidic group or a hydrophilic resin containing a basic group is a resin containing an acidic group or a basic group, and is neutralized with a basic neutralizing agent or an acidic neutralizing agent. There is no limitation as long as a coating material can be formed. Examples of the acidic group of the hydrophilic resin containing an acidic group include a carboxyl group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group, and a carboxyl group is preferable for electrodeposition coatings. Examples of the basic group of the hydrophilic resin containing a basic group include an amino group, an amide group, a pyridine group, a pyrrolidone group, an imidazole group, and an imine group, but an amino group is preferable for electrodeposition coatings.

  Examples of hydrophilic resins containing acidic groups or hydrophilic resins containing basic groups include acrylic resins, epoxy resins, styrene resins, olefin resins, vinyl ester resins, polyester resins, polyamide resins, Examples include polyurethane resins, poly (thio) ether resins, polycarbonate resins, polysulfone resins, polyimide resins, resins in which acidic groups or basic groups are introduced into cellulose ester resins, acrylic resins, epoxy resins A resin containing an acidic group or a basic group is easy to use as a preferred electrodeposition paint.

  As such a thing, the acrylic copolymer which has an acidic group or a basic group, and an epoxyamine adduct resin are preferable.

  The acrylic copolymer is obtained by copolymerizing a monomer having an acidic group or a basic group with another polymerizable monomer.

  The acrylic copolymer having an acidic group is obtained, for example, by copolymerizing a carboxyl group-containing monomer (a), a hydroxyl group-containing monomer (b), and another monofunctional monomer (c). It is done.

  As the carboxyl group-containing monomer (a), known monomers can be used, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, etc. Examples include compounds having a bond. Among these, acrylic acid and methacrylic acid are preferable. A carboxyl group-containing monomer can be used individually by 1 type, or can use 2 or more types together.

  A well-known thing can be used as a hydroxyl-group containing monomer (b), For example, (meth) acrylic-acid alkyl group alkyl, for example, (meth) acrylic-acid 2-hydroxyethyl, (meth) acrylic-acid 2-hydroxypropyl, ( And (meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 4-hydroxybutyl, caprolactone-modified (meth) acrylic acid hydroxy ester, and the like. Caprolactone-modified (meth) acrylic acid hydroxy ester is obtained by adding (meth) acrylic acid to caprolactone, and a commercially available product can be used. Examples of commercially available products in which (meth) acrylic acid is added to caprolactone include Plaxel FM1, Plaxel FM2, Plaxel FM3, Plaxel FA1, Plaxel FA2, Plaxel FA3 (registered trademark, manufactured by Daicel Chemical Industries). A hydroxy group containing monomer can be used individually by 1 type, or can use 2 or more types together. Of these, (meth) acrylic acid ester 2-hydroxyethyl is preferred. The hydroxy group-containing monomer is nonionic but can impart hydrophilicity to the copolymer. Here, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester.

  Other monofunctional monomers (c) are not particularly limited. For example, methyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylic acid 2 -(Meth) acrylic acid ester having an alkyl group having 1 to 18 carbon atoms such as ethylhexyl; aralkyl group-containing (meth) acrylic acid ester such as benzyl (meth) acrylate; cyclohexyl (meth) acrylate, isobornyl acrylate, Cyclic alkyl (meth) acrylic acid esters such as 2-acryloyloxyethyl hydrogen phthalate and 2-acryloyloxypropyl hydrogen phthalate; fluorinated alkyl (meth) such as 2- (perfluorooctyl) ethyl methacrylate and trifluoromethyl methacrylate Acrylic acid ester; vinyl acetate Le; N- phenylmaleimide, etc. N- cyclohexyl maleimide. These 1 type (s) or 2 or more types can be used together.

  In addition, the acrylic copolymer having a basic group includes, for example, an amino derivative (d) of (meth) acrylic acid, a hydroxyl group-containing monomer (b), and another monofunctional monomer (c). Obtained by polymerization.

  As the amino derivative (d) of (meth) acrylic acid, amino derivatives such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and ethyltrimethylammonium acrylate chloride can be used.

  As the hydroxyl group-containing monomer (b) and other monofunctional monomers (c), those described above can be used.

  About the compounding quantity of the monomer in an acrylic copolymer, the combination of said monomer (a), (b), (c) or (d), (b), (c) is performed by arbitrary ratios. be able to. Examples of the monomer content include 5 to 30% by weight of the carboxyl group-containing monomer (a) or (meth) acrylic acid amino derivative (d), and 5% of the hydroxy group-containing monomer (b). Those containing ˜30% by weight and 40 to 90% by weight of the other monofunctional monomer (c) are preferred. As the polymerization conditions, normal acrylic polymerization conditions can be preferably applied. In this case, it may be carried out in a known water-soluble organic solvent. For example, 40 to 80% by weight of the water-soluble organic solvent is used.

  The weight average molecular weight of the acrylic copolymer containing an acidic group or a basic group obtained by polymerization is preferably 1,000 to 40,000, particularly preferably 2,000 to 30,000. When the weight average molecular weight is 1,000 or more, the dispersibility in water is good, and precipitation of the electrodeposition coating itself is difficult to occur. When it is 40,000 or less, a defective appearance of coating such as yuzu skin does not occur and a uniform appearance can be obtained. In addition, the weight average molecular weight Mw of this acrylic copolymer can be measured by a gel permeation (GPC) method, for example, can be measured as follows.

  In a GPC apparatus (trade name: HLC-8220 GPC, manufactured by Tosoh Corporation), measurement is performed by injecting 100 ml of a sample solution using a column set at a temperature of 40 ° C. As a sample solution, a solution obtained by dissolving a 0.25% tetrahydrofuran solution of an acrylic copolymer (dry product) overnight is used. The molecular weight calibration curve is prepared using standard polystyrene (monodisperse polystyrene).

  Further, as the epoxyamine adduct resin, a derivative obtained by modifying the epoxy group of the epoxy resin with primary and secondary amines by 30 to 100% can be preferably used. For the reaction, those dissolved in 40 to 80% by weight of an aqueous organic solvent can be used.

  As epoxy resins, bisphenol A type epoxy resins [trade names: Epicoat 828, Epicoat 834, Epicoat 1001, Epicoat 1004, Epicoat 1007, Epicoat 1009 (above, manufactured by Japan Epoxy Resin Co., Ltd.)], novolak phenol type epoxy resin [trade name : Epicoat 152, Epicoat 154 (manufactured by Japan Epoxy Resin Co., Ltd.)], glycidylamine type epoxy resin [Product Name: Epicoat 604 (Japan Epoxy Resin)], and dimer acid type epoxy resin (Product Name: Epicoat 872 (Japan) Epoxy resin)]] can be used, but is not limited thereto.

Examples of the primary amine include monoalkanolamines having 1 to 4 carbon atoms such as monomethanolamine, monoethanolamine and monoisopropanolamine; monoalkylamines having 1 to 4 carbon atoms such as dimethylaminoethylamine, diethylaminoethylamine and diethylaminopropylamine. Secondary amines include dialkanolamines having 1 to 4 carbon atoms such as dimethanolamine, diethanolamine and diisopropanolamine; monoalkanols having 1 to 4 carbon atoms such as methylethanolamine and methylpropanolamine. Amine: Although a C1-C4 dialkylamine, such as diethylamine and di n-butylamine, can be used, it is not limited to these. The above alkanolamine is preferably used because it improves the hydrophilicity of the adduct.

  Primary and secondary amines can be added in response to epoxy groups. It is preferable to use 0.5 to 1.2 equivalents of primary or secondary amine H to 1 equivalent of epoxy group. The reaction is preferably performed at room temperature to 50 ° C. In this way, an epoxyamine adduct resin with an amino group added is obtained.

  The resin composition for coatings according to the present invention comprises 5 to 50% by weight of ceramic fine particles having thermal conductivity and insulating properties with respect to the total weight of the resin composition, and a hydrophilic resin or basic resin containing the acidic group. A hydrophilic resin containing a group is blended in an amount of 50 to 95% by weight.

  When the composition ratio of the ceramic fine particles is less than 5% by weight with respect to the resin composition for electrodeposition paints, sufficient thermal conductivity, heat dissipation and insulation cannot be obtained for the object to be coated, and exceeds 50% by weight. The resin composition is difficult to disperse or dissolve in water. Preferably it is 5 to 40 weight%, Most preferably, it is 10 to 30 weight%. When the hydrophilic resin containing an acidic group or the hydrophilic resin containing a basic group is less than 50% by weight based on the resin composition for electrodeposition coatings, a resin containing ceramic fine particles is dispersed or dissolved in water. Hard to do. If it exceeds 95% by weight, the eutectoid rate of the ceramic fine particles having thermal conductivity is lowered, sufficient heat dissipation is not obtained, and thermal conductivity and insulation are also poor. Preferably it is 60 to 95 weight%, Most preferably, it is 70 to 90 weight%.

  In addition, in order to express the insulating properties of the resin composition for electrodeposition paints and the general properties of the coating film, melamine resins such as methylated melamine resin, butylated melamine resin, and benzoguanamine resin; tolylene diisocyanate, diphenylmethane Diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and the like may be trimerized and blocked with methyl ethyl ketoxime, ε-caprolactam, phenol, diketone, etc .; a polyimide resin or the like may be mixed with the above resin. These resins can react and crosslink with functional groups such as hydroxyl groups and carboxyl groups of hydrophilic resins containing acidic groups or hydrophilic resins containing basic groups to enhance the performance of the resins.

  As the polyimide resin, a solvent-soluble imide resin in which the following (e) and (f) are reacted in an equimolar amount in an appropriate organic solvent and then subjected to dehydration ring-closing reaction to complete imidization can be used.

(E) Aromatic tetracarboxylic dianhydride 3,4,3 ′, 4′-benzosulfone tetracarboxylic dianhydride, 3,4,3 ′, 4′-diphenyltetracarboxylic dianhydride, bis -(3,4-dicarboxyphenyl) ether dianhydride, 2,2-bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, etc.

(F) Aromatic diamine 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 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-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl Sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, and the like.

  Moreover, N, N'-m-xylene bismaleimide, N, N'-4,4'-diphenylmethane bismaleimide, N, N'-m-phenylene bismaleimide, N, N'-4,4'-diphenyl ether bis Thermally crosslinkable imide compounds such as maleimide, N, N′-m-xylenebisnadiimide, and N, N′-4,4′-diphenylmethanebisallylnadiimide can also be used.

  These cross-linked resins can be applied to both acrylic copolymers and epoxyamine adduct resins, but acrylic copolymers can exhibit the characteristics of resins when used with melamine resins and epoxyamine adduct resins with polyimide resins. preferable. The blending amount of these melamine resins and polyimide resins is preferably 15 to 60% by weight, more preferably 20 to 50% by weight, based on the total amount of the resin.

(Water-based electrodeposition paint)
The aqueous electrodeposition coating material of the present invention contains the resin composition for electrodeposition coating materials of the present invention, an acidic or basic neutralizing agent (hereinafter sometimes simply referred to as neutralizing agent) and water. The aqueous electrodeposition coating composition of the present invention may be produced by adding a neutralizing agent to the resin composition for electrodeposition coating composition of the present invention and mixing it, then throwing it into water and dispersing it. After being dissolved, the resin composition for electrodeposition paints of the present invention may be added and dispersed for production. The former is preferred. The content of the resin composition for electrodeposition paints in the aqueous electrodeposition paint is preferably 5 to 20% by weight, more preferably 8 to 15% by weight, based on the total amount of the aqueous electrodeposition paint, as a solid content (coating film forming component). is there. When the content is 5% by weight or more and 20% by weight or less, the dispersion state of each component in the paint becomes stable, no aggregation / precipitation occurs, and a uniform coating film appearance is obtained.

  A hydrophilic resin containing an acidic group or a hydrophilic resin containing a basic group is obtained by dispersing ceramic fine particles having thermal conductivity and insulating properties in water and then applying thermal conductivity and insulating properties to an object by electrodeposition coating. To deposit ceramic fine particles.

  Examples of acidic neutralizing agents for dispersing hydrophilic resins containing basic groups in water include organic acids such as lactic acid, acetic acid, formic acid, succinic acid, butyric acid, and methanesulfonic acid, and inorganic acids such as hydrochloric acid and nitric acid. Can be used. Preference is given to organic acids.

  Basic neutralizing agents for dispersing hydrophilic resins containing acidic groups in water include amine neutralizing agents such as dimethylamine, trimethylamine, diethylamine, triethylamine, morpholine, pyridine; sodium carbonate, potassium carbonate, An inorganic neutralizing agent such as sodium hydroxide or potassium hydroxide can be used. Preference is given to amine-based neutralizing agents.

  The amount of these acidic neutralizers and basic neutralizers can be arbitrarily changed according to the content of acidic groups or basic groups of the hydrophilic resin, the solubility of the resin in water, and the like. However, it is preferably 0.2 to 8 g, more preferably 0.5 to 7 g, and particularly preferably 1 to 6 g based on 1 liter of the finished electrodeposition paint. When the content is 0.2% by weight or more, each hydrophilic resin is sufficiently water-soluble, and each hydrophilic resin is uniformly dispersed in water. If it is 5% by weight or less, the neutralizing agent hardly remains as an impurity, and there is no possibility of adversely affecting the cured coating film by heating after electrodeposition coating.

  The water-based electrodeposition paint mixed as described above can be dispersed in water with impregnation and wettability between the hydrophilic resin and the ceramic fine particles having thermal conductivity and insulation, and can be electrodeposited. Further, due to the characteristics of the composition, the use amount of the organic solvent is reduced, so that it has excellent characteristics in terms of safety and environment.

(Electrodeposition coating)
Electrodeposition coating using the aqueous electrodeposition paint of the present invention can be carried out in the same manner as conventional electrodeposition coating. For example, after subjecting the target base material to be coated to a degreasing treatment and pickling treatment as necessary, the target base material is immersed in the aqueous electrodeposition coating material of the present invention and energized. An uncured electrodeposition coating is formed on the surface of the material. By heating the object to be coated on which the uncured electrodeposition coating film is formed, a cured electrodeposition coating film is formed on the surface of the object to be coated.
The flowchart of the electrodeposition coating method of one embodiment in the present invention is shown in FIG.

First, weak alkali degreasing is performed in step S1. For example, it is performed by supplying an alkaline aqueous solution to the surface of the target substrate. The supply of the alkaline aqueous solution is performed, for example, by spraying the alkaline aqueous solution on the target base material or immersing the target base material 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 alkali concentration in the aqueous alkali solution is appropriately determined according to, for example, the type of metal to be treated and the degree of contamination. Furthermore, the alkaline aqueous solution may contain an appropriate amount of a surfactant such as an anionic surfactant and a nonionic surfactant. Degreasing is performed at a temperature of about 20 to 50 ° C. (liquid temperature of the alkaline aqueous solution) and is completed in about 1 to 5 minutes. In addition, degreasing to be immersed in an acidic bath, bubbling immersion degreasing, electrolytic degreasing, and the like can be appropriately combined.
In step S2, the target substrate is washed with water.

  In step S3, neutralization (pickling treatment) is performed with nitric acid having a concentration of 1%. The pickling treatment is performed, for example, by supplying an acid aqueous solution to the surface of the target substrate. The supply of the acid aqueous solution is performed by spraying the acid aqueous solution onto the target substrate, immersing in the acid aqueous solution, or the like, similarly to the supply of the alkaline aqueous solution in the degreasing treatment. As the acid, those commonly used for metal pickling can be used, and examples thereof include sulfuric acid, nitric acid, and phosphoric acid. The acid concentration in the acid aqueous solution is appropriately determined according to, for example, the type of metal to be treated. The pickling treatment is performed at a temperature of about 20 to 30 ° C. (liquid temperature of the acid aqueous solution) and is completed in about 15 to 60 seconds. In addition to the degreasing treatment and pickling treatment, scale removal treatment, ground treatment, rust prevention treatment, and the like may be performed.

In step S4, the target substrate is washed with water.
In step S5, ion-exchange water washing is further performed.

  In step S6, electrodeposition coating is performed. The electrodeposition coating is carried out in accordance with a known method, for example, by immersing the target substrate completely or partially in an energization tank filled with the aqueous electrodeposition paint of the present invention to form an anode and energizing. There are no particular restrictions on the electrodeposition coating conditions, and there are various conditions such as the type of solid that has electrical conductivity as the target substrate, the type of electrodeposition paint, the size and shape of the current-carrying tank, and the use of the object to be coated. The temperature can be selected appropriately from a wide range, but usually the bath temperature (electrodeposition paint temperature) is about 10 to 50 ° C., the applied voltage is about 10 to 450 V, the voltage application time is about 1 to 10 minutes, and the liquid temperature of the aqueous electrodeposition paint What is necessary is just to be 10-45 degreeC.

  Wash with water in step S7 and dry in step S8. The object to be coated with the electrodeposition coating is taken out from the energizing tank, washed with water and dried.

Baking is performed in step S9.
Baking includes pre-drying and curing heating. Curing heating is performed after preliminary drying. The preliminary drying is performed under heating at about 60 to 140 ° C. and is completed in about 3 to 30 minutes. Curing heating is performed under heating at about 150 to 220 ° C. and is completed in about 10 to 60 minutes. Thus, the electrodeposition coating film by the aqueous electrodeposition coating material of this invention is obtained.

  The target substrate in the present invention is applicable not only to metals but also to all solids having electrical conductivity such as semiconductors such as silicon and indium titanate, and electrically conductive ceramics. In other words, the target substrate is not limited as long as it can be electrodeposition-coated, but it can also be applied to stainless steel (SUS304), aluminum or anodized aluminum material, plating material or plated article, die casting, and the like.

  Any material commonly used in this field can be used as the plating material, such as pure iron, carbon steel, high tensile strength steel (low alloy steel, maraging steel), magnetic steel, nonmagnetic steel, high manganese steel, Stainless steel (martensitic stainless steel, ferritic stainless steel, austenitic stainless steel, austenitic / ferritic stainless steel, precipitation hardened stainless steel, etc.), iron-based metals such as superalloy steel, copper and copper alloys (oxygen-free copper, phosphor bronze, Tough pitch copper, aluminum bronze, beryllium copper, high-strength brass, red brass, western white, brass, free-cutting brass, Nevlar brass, etc.), iron / nickel alloy, nickel / chromium alloy, nickel, chromium, aluminum and aluminum alloy, magnesium And magnesium alloys, titanium, zirconium, hafnium and their alloys, Buden, tungsten and alloys thereof, niobium, tantalum and alloys thereof, ceramics such (alumina, etc. Jirukoa) and the like. The type of plating applied to the surface of the plating material is not particularly limited, and any plating commonly used in this field can be adopted. For example, copper / nickel / chrome plating, nickel / boron / tungsten plating, nickel / boron plating, brass plating, bronze plating, and other alloy plating, gold plating, silver plating, copper plating, tin plating, rhodium plating, palladium plating, Examples include platinum plating, cadmium plating, nickel plating, chromium plating, black chrome plating, zinc plating, black nickel plating, black rhodium plating, zinc plating, and industrial (hard) chromium plating. Examples of the die casting include zinc die casting, aluminum die casting, magnesium die casting, and sintered alloy die casting.

(Painted material)
A coated product obtained by electrodeposition-coating the above-mentioned aqueous electrodeposition coating is coated with a coating containing ceramic fine particles having thermal conductivity and insulating properties, so that a solid having electrical conductivity has both heat insulation and heat dissipation properties. Improvement of thermal conductivity can be realized.

Accordingly, the aqueous electrodeposition coating composition of the present invention is particularly suitably used for the following applications.
(1) Heat-dissipating and insulating coating on a circuit board Among LED boards and various device boards, a board-integrated type, a complicated structure, and a cooling pipe have been developed. Conventional alumite treatment makes it difficult to form a uniform heat dissipation film, and is difficult to apply as a heat dissipation treatment for such a substrate. For such parts, the aqueous electrodeposition coating of the present invention does not cause a chemical change of the substrate material, and can selectively and uniformly dissipate heat with a thin film having a thickness of a few tens of μm selectively only in necessary portions. The coating method of the present invention gives a great degree of freedom to the development and design of the substrate, and can also contribute to the cost by making use of the characteristics of the electrodeposition paint with good coating efficiency.

(2) Reflective plate of optical component Since the gloss of the target base material is lost in the conventional alumite treatment, it cannot be used for a reflective plate of an LED or a plasma luminous body. In the aqueous electrodeposition coating of the present invention, it is possible to impart heat dissipation and thermal conductivity without losing luster by selecting a particle size of ceramic fine powder having appropriate heat dissipation.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
Two types of aluminum oxide (A-1) and boron nitride (A-2) are used as ceramic fine particles having thermal conductivity and insulating properties, and two types of B-1 and B-2 are used as hydrophilic resins. It was. For comparison, tin oxide (A-3) was used.

[Synthesis of hydrophilic resin (B-1)]
A 4-necked flask equipped with a Dimroth reflux tube was charged with 43 g of diethylene glycol monoisopropyl ether and heated to reflux. Next, 5 g of acrylic acid, 20 g of methyl methacrylate, 30 g of 2-hydroxyethyl acrylate, 20 g of n-butyl acrylate, 25 g of styrene and 1 g of benzoin peroxide as a polymerization initiator were added and mixed uniformly. Moved to. A dropping funnel is attached to the four-necked flask, and the mixture is stirred with a motor to divide the monomer mixture into 8 portions and dropped at intervals of 10 minutes. The reaction was carried out at a reaction temperature of 70 to 80 ° C. for 5 to 6 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 was 70%, the viscosity was 20,000 mPa · s (25 ° C.), and the acid value was 35. A clear resin solution was obtained.

  Moreover, what mixed 100 weight part of said resin solutions and 30 weight part of benzoguanamine was made into hydrophilic resin B-1.

[Synthesis of hydrophilic resin (B-2)]
In a four-necked flask equipped with a Dimroth reflux tube, 500 g of Epicoat 1001 (epoxy resin, manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent: 474) and 300 g of propylene glycol monomethyl ether were mixed and dissolved. The liquid temperature was raised to 90 ° C. and maintained, and 180 g of diethanolamine was transferred to the dropping funnel. A dropping funnel was attached to the four-necked flask and stirred with a motor, and the amine was added dropwise in 60 minutes. After completion of the dropwise addition, the mixture was heated at 120 ° C. for 90 minutes to obtain a yellow transparent epoxy amine adduct resin solution having a solid content concentration of 70%, a viscosity of 13,000 mPa · s (25 ° C.), and a EQ of 180.

  In addition to the above, in a four-necked flask equipped with a Dimroth reflux tube, 0.5 mol of 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride and bis (4- (3-aminophenoxy) phenyl) sulfone 0.5 mol was diluted with N-methylpyrrolidone to a nonvolatile content of 20% and stirred at 25 ° C. for 24 hours. To the obtained polyamic acid, 30 g of toluene was added and refluxed at 140 ° C. for 4 hours to perform a dehydration ring-closing reaction, water generated by the dehydration reaction with toluene was removed from the reaction system, and the solid content concentration: 20%, A brown transparent polyimide resin solution having a logarithmic viscosity of 0.6 was obtained.

  Next, a mixture of 70 parts by weight of the epoxyamine adduct resin, 100 parts by weight of the polyimide resin solution, and 20 parts by weight of a phenol block of tolylene diisocyanate trimer was mixed with the hydrophilic resin B-2. It was.

(Examples 1-4 and Comparative Example 1)
(1) Preparation of paints For Examples 1 to 4, the hydrophilic resin obtained above and ceramic fine particles having thermal conductivity and insulating properties were mixed in an appropriate amount and dispersed in water with a neutralizing agent. Table 1 shows the resin amount, neutralizing agent amount, and stirring conditions for each example. Table 1 also shows the pH of the water-based electrodeposition paint prepared and the electrical conductivity of the paint.

  In Comparative Example 1, a paint was prepared using only the hydrophilic resin B-2. In addition, the numerical value in Table 1 is the gram number contained in 1 liter of water-based electrodeposition coating materials.

  As can be seen from Table 1 below, the solvent concentration in the paints of Examples 1 to 8 is as low as 1.5%, has high safety, and has little influence on the environment.

(2) Electrodeposition coating experiment Next, electrodeposition coating was performed on the test piece.

  The aqueous electrodeposition paints of Examples 1 to 4 and Comparative Examples 1 and 2 are placed in a 1 liter tank, and the liquid temperature is maintained at 25 ° C. Electrodeposition coating was performed using a carbon plate for the anode and a SUS304 plate (50 × 50 mm) as a test piece for the cathode. Specific conditions are shown according to FIG.

  First, in step S1, the SUS304 plate was subjected to weak alkali degreasing at 50 ° C. for 5 minutes, and washed in step S2. In step S3, neutralization was performed at room temperature for 1 minute using nitric acid having a concentration of 1%, and the mixture was washed with water in step S4. In step S5, ion-exchange water washing was performed, and in step S6, electrodeposition coating was performed at a voltage of 100 V for 1 minute. After washing with water at step S7 and drying at step S8 (15 minutes at 100 ° C.), finally, baking at 180 ° C. for 30 minutes was performed at step S9.

  General evaluation items of the coating film were film thickness (JIS K5600), appearance (visual observation), pencil hardness (JIS K5600), cross-cut peel test (JIS K5600), volume resistance value, and dielectric breakdown voltage.

About the film thickness, it was 9-14 micrometers about the coating materials of Examples 1-4 and Comparative Examples 1 and 2, and all the coated articles showed the smooth external appearance.
The pencil hardness test was 4H for the paints of Examples 1 to 4 and Comparative Examples 1 and 2.

  The cross-cut peel test was 100/100 for the paints of Examples 1 to 4 and Comparative Examples 1 and 2.

  Regarding the glass transition temperature, Examples 2 and 4 and Comparative Examples 1 and 2 showed high temperatures reflecting the properties of the hydrophilic resin.

  In the dielectric breakdown voltage, Examples 1 to 4 and Comparative Example 2 showed good numerical values. In particular, Examples 2 and 4 exhibited higher dielectric breakdown voltages reflecting the properties of the hydrophilic resin.

The heat dissipation characteristics were measured for the following with a film thickness of 10 μm. For comparison, an alumite-treated aluminum plate and SUS304 plate were also used at the same time. The results are shown in Table 2.
(I) Infrared average emissivity at a sample temperature of 100 ° C. and a wave number of 4000 cm ^{−1 to} 400 cm ⁻¹ (ii) The difference between the heat source temperature and the sample temperature (using a thermograph)

In the infrared average emissivity at wave numbers of 4000 cm ^{−1 to} 400 cm ⁻¹ , the paints of Examples 1 to 4 and Comparative Example 1 showed emissivities equivalent to those of the anodized plate, whereas Comparative Example 2 greatly decreased. is doing.

  Regarding the difference between the heat source temperature and the sample temperature, in Examples 1 to 4, the thermal conductivity equivalent to that of the alumite plate was shown.

  Regarding the heat dissipation characteristics, Examples 1 to 4 are coated on a SUS plate, which indicates that insulating and thermal conductivity functions that cannot be achieved with a SUS plate can be imparted to the surface.

  As described above, the water-based electrodeposition paint of the present invention can impart heat dissipation to metals, semiconductors, and electrically conductive ceramics that are not inherently thermally conductive, and can provide insulation. It also has excellent characteristics in terms of safety and environment.

  The resin composition for electrodeposition coating and the aqueous electrodeposition coating of the present invention can be suitably used for solid electrodeposition coating having electrical conductivity.

Claims (7)

  A resin composition comprising ceramic fine particles having thermal conductivity and insulating properties and a hydrophilic resin containing an acidic group, the ceramic having thermal conductivity and insulating properties relative to the total weight of the resin composition A resin composition for electrodeposition coatings comprising 5 to 50% by weight of fine particles and 50 to 95% by weight of a hydrophilic resin containing the acidic group.   A resin composition comprising ceramic fine particles having thermal conductivity and insulating properties and a hydrophilic resin containing a basic group, wherein the thermal conductivity and insulating properties are relative to the total weight of the resin composition. A resin composition for an electrodeposition coating comprising 5 to 50% by weight of ceramic fine particles and 50 to 95% by weight of a hydrophilic resin containing the basic group.   An aqueous electrodeposition paint capable of being applied to a solid having electrical conductivity, wherein the resin composition for electrodeposition paint according to claim 1 is dispersed in water containing a basic neutralizing agent.   An aqueous electrodeposition paint capable of being applied to a solid having electrical conductivity, wherein the resin composition for electrodeposition paint according to claim 2 is dispersed in water containing an acidic neutralizing agent.   A method for electrodeposition coating a solid having electrical conductivity using the aqueous electrodeposition paint according to claim 3 or 4.   A coated product obtained by electrodeposition-coating a solid having electrical conductivity by the electrodeposition coating method according to claim 5.   7. The coated object according to claim 6, wherein the electrically conductive solid is a circuit board or a reflector of an optical component.

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