JP2021046538A - Resin composition and thermally cured product - Google Patents

Abstract

To provide a resin composition and a thermally cured product which make an insulation coating film have lower dielectric constant while suppressing reduction in hardness of an isolation layer by homogeneously dispersing hollow particles, and can improve partial discharge starting voltage.SOLUTION: The present invention is a resin composition and a thermally cured product containing: polyamic acid (A); hollow particles (B) with the number average particle diameter of 0.1 to 30 μm; and compound (C) expressed by the following general formulas (1) or (3), in which the volume ratio (vol%) of the hollow particles (B) is 10 to 40 with respect to the total volume of the polyamic acid (A) and the hollow particles (B).SELECTED DRAWING: None

Description

The present invention relates to resin compositions and thermosetting products.

Partial discharge in electrical equipment occurs when there are minute gaps in or between wires in an insulator such as an electric wire or cable, the electric field concentrates on that part, and a weak discharge occurs. When a partial discharge occurs, a local temperature rise and generation of ions are caused, causing dielectric breakdown of electric wires and cables at an early stage, shortening the life of insulated electric wires and electrical equipment.

In the windings used for coils such as motors and transformers, especially in insulated wires where resin paint is applied on conductors and baked to form an insulating film, partial discharge is mainly caused by internal defects in the insulating material or minute cavities. It is generated by foreign matter, and erosion of the film progresses due to molecular chain breakage of the resin film due to collision of charged particles, heat generation, etc., leading to dielectric breakdown.

Further, in recent years, in a system for driving an inverter motor or the like used for energy saving and variable speed, an inverter surge (steep overvoltage) occurs in many cases, causing dielectric breakdown. It is known that this dielectric breakdown is caused by the overvoltage caused by the inverter surge causing partial discharge.

As a method of improving the life of insulated wires used for coils of motors and transformers, a method of suppressing erosion of the insulating film due to partial discharge and insulation by forming an insulating film using a resin paint filled with an inorganic material. There is a method of suppressing the occurrence of partial discharge by lowering the dielectric constant of the coating film.

Among the inorganic materials, as a method of dispersing silica fine particles in a resin solution, a method of adding and dispersing silica particle powder in a resin solution, a method of mixing a resin paint and an organosilica sol, and the like are known (Patent Documents 1 and 2). ). When silica particles or organosilica sol are used, a paint in which silica is dispersed can be obtained, and an insulated wire having good characteristics such as flexibility, flexibility, wrapability, and extensibility can be obtained. It is necessary to use one with good compatibility.

As a method of reducing the dielectric constant of the insulating film, there is a method of making the insulating film porous, and the coating resin and the thermally decomposable resin which decomposes at a temperature lower than the baking temperature of the coating resin are separated. A method of forming an exfoliated film with an insulating varnish containing the resin is known (Patent Document 3). In this insulated wire, the thermally decomposed resin is thermally decomposed at the time of baking the coating film constituent resin to form pores, thereby obtaining a porous insulating film.

However, when the inorganic materials described in Patent Documents 1 and 2 are used, the dielectric constant of the inorganic material is generally higher than that of the organic material, so that it is difficult to suppress the partial discharge itself, and the thermal decomposition described in Patent Document 3 is used. When a sex resin is used, pores are localized and the size of the pores varies due to aggregation of particles, continuous pores are likely to occur, the strength of the insulating film is reduced, and dielectric breakdown occurs at an early stage. There's a problem.

Japanese Unexamined Patent Publication No. 2001-307557 Japanese Unexamined Patent Publication No. 2004-204187 Japanese Unexamined Patent Publication No. 2012-224714

The purpose of the resin composition and the thermosetting product of the present invention is to reduce the dielectric constant of the insulating coating and improve the partial discharge starting voltage while suppressing the decrease in the strength of the insulating layer by uniformly dispersing the hollow particles. ..

The present invention comprises a polyamic acid (A), hollow particles (B) having a number average particle diameter of 0.1 to 30 μm, and a compound (C) represented by the following general formula (1) or (3). The resin composition contained therein, wherein the volume ratio (vol%) of the hollow particles (B) is 10 to 40 with respect to the total volume of the polyamic acid (A) and the hollow particles (B). ..

［一般式（１）中、Ｒは炭素数１〜２４のアルキル基又はアルケニル基を表す。Ａ_１Ｏは炭素数２〜６のアルキレンオキシ基から選ばれる少なくとも１種である。ｅは１以上１００以下の整数であり、ｅが２以上の場合複数あるＡ１Ｏは同一でも異なっていてもよい。−（Ａ_１Ｏ）_ｅ−Ｈは下記一般式（２）で表される末端基を有する。］

[In the general formula (1), R represents an alkyl group or an alkenyl group having 1 to 24 carbon atoms. A ₁ O is at least one selected from alkyleneoxy groups having 2 to 6 carbon atoms. e is an integer of 1 or more and 100 or less, and when e is 2 or more, a plurality of A1Os may be the same or different. − (A ₁ O) _e −H has a terminal group represented by the following general formula (2). ]

［Ａ_２Ｏは炭素数２〜６のアルキレンオキシ基から選ばれる１種であり、ｇは１以上１００以下の整数である。］

[A ₂ O is one selected from alkyleneoxy groups having 2 to 6 carbon atoms, and g is an integer of 1 or more and 100 or less. ]

［一般式（３）中、Ａ_３Ｏ、Ａ_４Ｏ及びＡ_５Ｏはそれぞれ炭素数２〜６のアルキレンオキシ基から選ばれる１種であり、互いに隣り合うＡ_３ＯとＡ_４Ｏ、Ａ_４ＯとＡ_５Ｏは互いに異なる炭素数のアルキレンオキシ基であり、ｈ、ｉ及びｊはそれぞれ１以上１５０以下の整数であり、ｈ＋ｉ＋ｊは５０以上２５０以下の整数である。］

[In the general formula (3), A ₃ O, A ₄ O and A ₅ O are one selected from alkyleneoxy groups having 2 to 6 carbon atoms, respectively, and are adjacent to each other, A ₃ O and A ₄ O, A. ₄ O and A ₅ O are alkyleneoxy groups having different carbon atoms, h, i and j are integers of 1 or more and 150 or less, respectively, and h + i + j are integers of 50 or more and 250 or less. ]

In the resin composition and the thermosetting product of the present invention, the hollow particles are uniformly dispersed to suppress a decrease in the strength of the insulating layer, reduce the dielectric constant of the insulating coating, and improve the partial discharge starting voltage.

The resin composition of the present invention comprises a polyamic acid (A), hollow particles (B) having a number average particle diameter of 0.1 to 30 μm, and a compound represented by the above general formula (1) or (3). C) and.

<Polyamic acid (A)>
As the polyamic acid (A), one obtained by polymerizing tetracarboxylic dianhydride and diamine can be used without particular limitation.

Even if the tetracarboxylic dianhydride is an aromatic tetracarboxylic dianhydride, it is an aliphatic tetracarboxylic dianhydride (acyclic aliphatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride). However, from the viewpoint of the heat resistance of the obtained polyimide, it is preferable to use an aromatic tetracarboxylic dianhydride or an alicyclic tetracarboxylic dianhydride. As the tetracarboxylic dianhydride, one type may be used alone, or two or more types may be used in combination.

Suitable aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, and bis (2,3-dicarboxyphenyl). Methan dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 2,3,3', 4'-biphenyltetra Carboxyl dianhydride, 2,2,6,6-biphenyltetracarboxylic hydride, 2,2-bis (3,4-dicarboxyphenyl) propane hydride, 2,2-bis (2,3) -Dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) 2,3-Dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, bis (3,3) 4-Dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, 2,2', 3,3'-benzophenone tetracarboxylic acid dianhydride, 4,4- (p. -Phenylenedioxy) diphthalic acid dianhydride, 4,4- (m-phenylenedioxy) diphthalic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8 -Naphthalenetetracarboxylic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,2,3,4-benzenetetracarboxylic acid dianhydride, 3,4,9,10-perylene Tetracarboxylic acid dianhydride, 2,3,6,7-anthracene tetracarboxylic acid dianhydride, 1,2,7,8-phenanthrene tetracarboxylic acid dianhydride, 9,9-bisfluorene phthalate, 3 , 3', 4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 4,4'-bis (3,4-dicarboxyphenoxy) diphenyl ether dianhydride, 4,4'-bis (2,3-di) Examples thereof include carboxyphenoxy) diphenyl ether acid dianhydride and 4- (2,3-dicarboxyphenoxy) -4'-(3,4-dicarboxyphenoxy) diphenyl ether acid dianhydride.

As the aromatic tetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride are preferable from the viewpoint of heat resistance and film forming property.

Among the aliphatic tetracarboxylic dianhydrides, examples of the acyclic aliphatic tetracarboxylic dianhydride include ethylenetetracarboxylic dianhydride and butanetetracarboxylic dianhydride, and the alicyclic tetracarboxylic dianhydride. Examples of the carboxylic acid dianhydride include cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 1,2,3,4-cyclohexane. Examples thereof include tetracarboxylic dianhydride.

The diamine can be appropriately selected from diamines conventionally used as a synthetic raw material for polyamic acid. As the diamine, aromatic diamines and aliphatic diamines (including acyclic aliphatic diamines and alicyclic diamines) are preferable from the viewpoint of heat resistance of the obtained polyimide, and aromatic diamines and alicyclic diamines are further preferable. preferable. One type of diamine may be used alone, or two or more types may be used in combination.

Examples of the aromatic diamine include a diamino compound having one or 2 to 10 phenyl groups bonded thereto. Specifically, phenylenediamine and its derivatives, diaminobiphenyl compounds and their derivatives, diaminodiphenyl compounds and their derivatives, diaminotriphenyl compounds and their derivatives, diaminonaphthalene and its derivatives, aminophenylaminoindane and its derivatives, diaminotetraphenyl. Compounds and derivatives thereof, diaminohexaphenyl compounds and derivatives thereof, cardo-type fluorangeamine derivatives, diaminodiphenyl ether compounds and derivatives thereof.

The number of carbon atoms of the aliphatic diamine is preferably 2 to 15 from the viewpoint of flexibility and the like. Among these, examples of the acyclic aliphatic diamine include pentamethylenediamine, hexamethylenediamine and heptamethylenediamine.
Examples of the alicyclic diamine include 1,4-cyclohexanediamine, 1,2-cyclohexanediamine, 4,4'-methylenebis (cyclohexylamine), 4- (2-aminoethyl) cyclohexylamine, and 4,4'methylenebis (2). -Methylcyclohexylamine), isophoronediamine, 1,3-bis (aminomethyl) cyclohexane and the like.

The hydrogen atom of these diamines may be a compound substituted with at least one substituent selected from the group such as a halogen atom, a methyl group, a methoxy group, a cyano group and a phenyl group.

As the diamine, it is preferable to use para-phenylenediamine or 4,4'-bis (3-aminophenoxy) biphenyl from the viewpoint of heat resistance and mechanical strength of the thermosetting product.

The polymerization reaction of the tetracarboxylic dianhydride and the diamine can be carried out by mixing the tetracarboxylic dianhydride and the diamine in a solvent and heating the mixture. The solvent used for the reaction between the tetracarboxylic dianhydride and the diamine is particularly limited as long as it can dissolve the tetracarboxylic dianhydride and the diamine and does not react with the tetracarboxylic dianhydride and the diamine. Not done. One type of solvent may be used alone, or two or more types may be used in combination.

Examples of solvents used in the reaction of tetracarboxylic acid dianhydride with diamine in the production of polyamic acid (A) include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, and the like. Examples thereof include γ-butyrolactone, γ-valerolactone, ε-caprolactone, dimethyl sulfoxide, acetonitrile, diethylene glycol diethyl ether, dioxane, tetrahydrofuran and water. From the viewpoint of solubility of tetracarboxylic dianhydride and diamine in a solvent, N, N-dimethylformamide and N-methyl-2-pyrrolidone are preferable.

The polymerization temperature is −10 to 120 ° C., preferably 5 to 30 ° C. from the viewpoint of production stability. When the reaction is carried out at a temperature exceeding 120 ° C., the molecular weight fluctuates depending on the temperature history at the time of polymerization, and imidization proceeds due to heat, so that the polyimide precursor may not be stably produced. The polymerization time varies depending on the raw material composition used, but is preferably 3 to 24 hours. As the polyamic acid, one type may be used alone, or two or more types may be used in combination.

Preferred polyamic acids used in the present invention include aromatic polyamic acid (polyamic acid made from at least one of aromatic tetracarboxylic acid dianhydride and aromatic diamine) and alicyclic polyamic acid (alicyclic tetra). Examples thereof include polyamic acids (polyamic acids made from at least one of a carboxylic acid dianhydride and an alicyclic diamine). As the polyamic acid, one kind or two or more kinds can be used. Commercially available products include Upia series (made by Ube Industries), Spixeria series (made by Somar), HCI series (made by Hitachi Kasei), HPC series (made by Hitachi Kasei), Uimide (made by Unitika), Aurum (manufactured by Mitsui Kagaku Co., Ltd.), Ultem (manufactured by GE Plastic Co., Ltd.), Neoheat (manufactured by Totoku Toryo Co., Ltd.) and the like can be mentioned.

<Hollow particles (B)>
The hollow particles (B) are hollow particles having a number average particle diameter of 0.1 to 30 μm. The particle size is preferably 0.1 to 10 μm, more preferably 0.3 to 1 μm from the viewpoint of dielectric constant.
The number average particle size is an arithmetic mean particle size in the number-based distribution of the particle size obtained by the laser light scattering method. It is a value obtained by measuring using a laser diffraction / scattering type particle size distribution measuring device (LA-920 (manufactured by HORIBA)). The measurement procedure is as follows. A sample can be prepared by adding 1% by weight of hollow particles (B) and 0.1% by weight of a dispersant based on the weight of N-methyl-2-pyrrolidone (NMP) or water and dispersing the particles by ultrasonic waves for 5 minutes. When silica hollow particles are used as the hollow particles (D), the dispersion medium is NMP, and the dispersant is a block copolymer of ethylene oxide (EO) and propylene oxide (PO) (manufactured by Sanyo Kasei Kogyo Co., Ltd .: New Pole PE-68). Alternatively, when PMMA hollow particles are used as a pluronic type dispersant such as PE-64), the dispersion medium is water, and the dispersant is an oleyl alcohol EO adduct (manufactured by Sanyo Kasei Kogyo Co., Ltd .: Emalmin V-100). It is preferable to use a dispersant containing a long-chain alkyl group such as. When the number average particle size exceeds 30 μm, it is not preferable from the viewpoint of insulating property.

The material of the hollow particles is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include inorganic hollow particles and organic hollow particles, and silica hollow particles, resin hollow particles and the like are preferably used.

The silica hollow particles are hollow particles composed of silica whose main component is silicon oxide and which is amorphous.

The silica hollow particles were kneaded with an epoxy resin and cured, and then the sample was cut. Then, an SEM photograph of the fractured surface is taken using a field emission scanning electron microscope (S-4000 manufactured by Hitachi, Ltd.). Observe the particle size and inner diameter of any 100 or more particles taken in this picture. At this time, the average particle diameter and the average inner diameter can be obtained by measuring the particle diameter and the inner diameter of five or more particles and calculating the average value. Further, the hollow ratio of the hollow particles is obtained from the formula (average inner diameter) ³ / (average particle diameter) ^{3 × 100.}
From the viewpoint of the relative permittivity, the hollow ratio of the silica hollow particles is preferably 40 vol% or more, and more preferably 40 vol% or more and 80 vol% or less.

Examples of commercially available silica hollow particles include Sirinax (manufactured by Nittetsu Mining Co., Ltd.), Godball series (manufactured by Suzuki Yushi Kogyo Co., Ltd.), THRULA (manufactured by JGC Catalysts and Chemicals Co., Ltd.), and the like.

The resin hollow particles are preferably hollow particles made of a resin having a structural unit derived from methyl methacrylate.

The method for synthesizing the resin hollow particles having a structural unit derived from methyl methacrylate is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a vinyl monomer, a surfactant, a polymerization initiator, and an aqueous system are used. A so-called emulsion polymerization method in which a hollow particle emulsion is formed by stirring the dispersion medium while heating it in a nitrogen atmosphere is preferable, and the method described in JP-A-2007-27096 or the like can be used.

Examples of the vinyl monomer include a nonionic monofunctional ethylene unsaturated monomer and a bifunctional vinyl monomer. These may be used alone or in combination of two or more.

Examples of the nonionic monofunctional ethylene unsaturated monomer include styrene, vinyltoluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth) acrylamide, and (meth) acrylic acid ester. These may be used alone or in combination of two or more.

Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and benzyl (meth) acrylate. , Lauryl (meth) acrylate, oleyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate and the like.

Examples of the bifunctional vinyl monomer include divinylbenzene, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1,5-butanediol di (meth) acrylate and diethylene glycol di (meth) acrylate.

As the polymerization initiator, a known compound that is soluble in water can be used, and examples thereof include hydrogen peroxide and potassium persulfate. These may be used alone or in combination of two or more.

The surfactant may be any one that forms molecular aggregates such as micelles in water, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. These may be used alone or in combination of two or more.

Examples of the aqueous dispersion medium include water and water containing a hydrophilic organic solvent.

Examples of the resin used for the resin hollow particles are preferably polystyrene, polymethylmethacrylate, polyurethane and ethylacrylate from the viewpoint of thermal decomposability, more preferably polystyrene and polymethylmethacrylate, and particularly preferably polymethylmethacrylate.

Examples of commercially available resin hollow particles include the Techpolymer series (manufactured by Sekisui Plastics Co., Ltd.).

TEM photographs of the resin hollow particles are taken under the condition of an acceleration voltage of 80 kV using a transmission electron microscope (H-7600 manufactured by Hitachi High-Technologies Corporation). At this time, the particles can be confirmed more clearly by using ruthenium tetroxide staining or the like. Observe the particle size and inner diameter of any 100 or more particles taken in this picture. At this time, the average particle diameter and the average inner diameter are obtained by measuring and averaging the particle diameters and inner diameters of five or more points so as to pass through the center of the particles. Further, the hollow ratio of the hollow particles is obtained from the formula (average inner diameter) ³ / (average particle diameter) ^{3 × 100.} From the viewpoint of thermal decomposition, the hollow ratio of the fine particles is preferably 20 vol% or more, and more preferably 20 vol% or more and 60 vol% or less.

<Compound (C)>
The resin composition of the present invention contains the compound (C) represented by the following general formula (1) or (3).

As the compound represented by the general formula (1), R represents an alkyl group or an alkenyl group having 1 to 24 carbon atoms. Specifically, the alkyl groups having 1 to 24 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group and linear chain. Or a branched pentyl group, a linear or branched hexyl group, a linear or branched heptyl group, a linear or branched octyl group, a linear or branched nonyl group, a linear or branched decyl group, a linear or branched group. Branched undecyl group, linear or branched dodecyl group, linear or branched tridecyl group, linear or branched tetradecyl group, linear or branched pentadecyl group, linear or branched hexadecyl group, linear or branched heptadecyl Group, linear or branched octadecyl group, linear or branched nonadesyl group, linear or branched icosyl group, linear or branched henicosyl group, linear or branched docosyl group, linear or branched tricosyl group and Examples thereof include a linear or branched tetracosyl group. From the viewpoint of dispersibility of the hollow particles, an alkyl group or an alkenyl group having 14 to 24 carbon atoms is preferable. More preferably, it is an alkyl group or an alkenyl group having 16 to 22 carbon atoms.

_{A 1} O in the general formula (1) is at least one group selected from alkyleneoxy groups having 2 to 6 carbon atoms. Examples of the alkyleneoxy group having 2 to 6 carbon atoms include an ethyleneoxy group, a 1,2-propyleneoxy group, a 1,3-propyleneoxy group, a butyleneoxy group and a hexyleneoxy group. From the viewpoint of solubility of the compound (C) in the solvent contained in the polyamic acid (A), an ethylene oxide group is preferable.

E in the general formula (1) is an integer of 1 or more and 100 or less. From the viewpoint of solubility in a solvent, e is preferably an integer of 30 or more and 90 or less. If e is 2 or more, a plurality of A _{1 O} may be the same or different.

-(A ₁ O) _e- H in the general formula (1) has a terminal group represented by the following general formula (2).

A ₂ O is one selected from alkyleneoxy groups having 2 to 6 carbon atoms, and the alkyleneoxy groups having 2 to 6 carbon atoms include ethyleneoxy groups, 1,2-propyleneoxy groups, and 1,3-propylene. Examples thereof include an oxy group, a butyleneoxy group and a hexyleneoxy group. From the viewpoint of solubility in a solvent, an ethylenexi group, a 1,2-propyleneoxy group and a 1,3-propyleneoxy group are preferable, and an ethyleneoxy group is more preferable.

The g contained in the group represented by the general formula (2) is an integer of 1 or more and 100 or less, and g is preferably an integer of 30 or more and 90 or less from the viewpoint of solubility in a solvent.

_{A 3} O, A ₄ O and A ₅ O in the compound represented by the general formula (3) are one selected from alkyleneoxy groups having 2 to 6 carbon atoms, respectively, and are alkyleneoxy groups having 2 to 6 carbon atoms. Examples thereof include ethyleneoxy group, 1,2-propyleneoxy group, 1,3-propyleneoxy group, butyleneoxy group and hexyleneoxy group. From the viewpoint of particle dispersibility, 1,2-propyleneoxy group, 1,3-propyleneoxy group and butyleneoxy group are preferable, and 1,2-propyleneoxy group and / or 1,3-propyleneoxy group are more preferable. Is the basis. Adjacent to each other, A ₃ O and A ₄ O, A ₄ O and A ₅ O are alkyleneoxy groups having different carbon numbers, and A ₃ O and A ₅ O are alkyleneoxy groups having the same carbon number. Good.

H, i and j in the compound represented by the general formula (3) are integers of 1 or more and 150 or less, respectively, and are integers of 30 or more and 140 or less from the viewpoint of solubility in a solvent and dispersibility of particles. h + i + j is an integer of 3 or more and 250 or less, and is preferably an integer of 50 or more and 230 or less from the viewpoint of solubility in a solvent.

The volume ratio (vol%) of the hollow particles (B) of the present invention to the total volume of the polyamic acid (A) and the hollow particles (B) is 10 to 40, preferably 20 to 35 from the viewpoint of the strength of the insulating coating. is there.

The volume ratio (vol%) can be calculated by the following formula using the volume derived by dividing the weights of the hollow particles (B) and the polyamic acid (A) by their respective specific gravities.
Volume ratio of hollow particles (B) (vol%) = Volume of hollow particles (B) / Total volume of polyamic acid (A) and hollow particles (B) x 100
Similarly, the polyamic acid (A) volume ratio (vol%) can be calculated by the following formula.
Volume ratio of polyamic acid (A) (vol%) =
Volume of polyamic acid (A) / Total volume of polyamic acid (A) and hollow particles (B) x 100
The specific gravity can be measured by, for example, the measurement method using a specific gravity bin among the solid specific gravity measuring methods in JISZ8807.

The weight ratio (wt%) of the polyamic acid (A) of the compound (C) of the present invention to the total weight of the hollow particles (B) and the compound (C) is 0.001 to 1 from the viewpoint of insulating properties. It is preferably 0.01 to 0.1.

The solubility parameter (cal / cm ³ ) ^1/2 (hereinafter abbreviated as SP value) of the compound (C) is set to the polyamic acid (A) when water is used as the solvent for adjusting the polyamic acid (A). From the viewpoint of the solubility of the compound (C) in the contained water and the dispersion stability of the hollow particles (B), it is preferably 9.2 to 12.5, more preferably 9.5 to 12.0, and particularly preferably 9.5 to 12.0. It is preferably 10.0 to 11.5. When NMP is used as the solvent for adjusting the polyamic acid (A), it may be 8.5 to 12.0 from the viewpoint of the solubility of the compound (C) in the NMP contained in the polyamic acid (A). It is preferable, more preferably 8.7 to 11.5, and particularly preferably 8.9 to 11.2.
The SP value in the present invention is described in Polymer Engineering and Science, February, 1974, Vol. 14, No. It is a value calculated by the Fedors method described in 2,147-154, and is calculated by the following equation.
SP value = (ΔH / V) ^1/2
In the formula, ΔH represents the molar heat of vaporization (cal) and V represents the molar volume (cm ³ ).

<Thermosetting resin (D)>
A thermosetting resin (D) such as polyamide-imide and polyimide can be synthesized from the polyamic acid (A) as a raw material. The thermosetting resin (D) is preferably polyimide from the viewpoint of heat resistance.

As a method for producing polyimide, by chemically imidizing or thermally imidizing the same or different polyamic acids, the amide nitrogen in the polyamic acid molecule and the carbonyl carbon of the carboxyl group undergo a nucleophilic reaction, followed by a dehydration reaction. A method such as imidization by occurrence can be used.

Specific examples of the cyclization catalyst (imidization catalyst) used in producing the above-mentioned polyimide include aliphatic tertiary amines such as trimethylamine and triethylenediamine, aromatic tertiary amines such as dimethylaniline, and isoquinolin and pyridine. And heterocyclic tertiary amines such as β-picoline, etc., which can be used alone or in combination of two or more. Among them, it is preferable to use at least one heterocyclic tertiary amine.

The polyamic acid used in the present invention can be used as a raw material for producing polyamide-imide by reacting with diisocyanate or diamine.

Examples of the method for producing polyamideimide include (i) a method of reacting an acid having a carboxyl group and an acid anhydride group in one molecule such as trimellitic anhydride with diisocyanate, and (ii) trimellitic anhydride chloride. In the precursor polymer (polyamellitic acid, which is a polyamideimide precursor) obtained by the reaction of the above-mentioned acid-reactive derivative with diamine, the amide nitrogen in the molecule and the carbonyl carbon of the carboxyl group undergo a nucleophilic reaction, and then dehydration occurs. A known method such as a method of imidizing by causing a condensation reaction can be used.

Examples of the acid or its reactive derivative used in the production of the polyamide-imide include trimellitic anhydride, trimellitic anhydride such as trimellitic anhydride, and trimellitic anhydride ester.

The diisocyanate used in the production of the above polyamide diis is not particularly limited, and examples thereof include diisocyanide compounds corresponding to any diamine. Specific examples thereof include metaphenylene diisocyanate, p-phenylenediocyanis, o-trizine diisocyanate, and p. -Phenylene diisocyanate, m-phenylenedi isocyanate, 4,4'-oxybis (phenylisocyanide), 4,4'-diisocyanide diphenylmethane, bis [4- (4-isocyanene phenoxy) phenyl] sulfone, 2,2'-bis [4 -(4-Isylene phenoxy) phenyl] propane, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, Examples thereof include 3,3'-diethyldiphenyl-4,4'-diisocyanis, isophorone diisocyanis, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate and naphthalenedi isocyanate.

In addition to the polyamic acid (A), the hollow particles (B), and the compound (C), the resin composition of the present invention contains a solvent, a defoaming agent, a leveling agent, a flame retardant, an antioxidant, an ultraviolet inhibitor, and light. Stabilizers, plasticizers and the like can be included.
The solvent is not particularly limited, and may include, for example, a polyamide-imide precursor used in the present invention or a solvent derived from a solvent used in the production of the polyimide precursor. Examples of the solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, γ-butyrolactone, γ-valerolactone, ε-caprolactone, dimethyl sulfoxide, acetonitrile, diethylene glycol diethyl ether, and dioxane. , Tetrahydrofuran, water and the like. One or more selected from other solvents in which polyimide or polyamic acid is soluble can be used.

<Thermosetting product>
The thermosetting product of the present invention is a thermosetting product of a resin composition.
As a method for molding a thermosetting product, for example, a resin composition is coated on a coated base material by a known method such as spin coating, slit coating, slot die coating and blade coating, and then baked to form a resin composition. Examples thereof include a method of curing the resin composition by a step of condensing the polyamic acid (A) contained in the substance. As the coating base material, a metal conductor such as copper, a copper alloy wire, or an aluminum wire is used. The diameter of the base material and its cross-sectional shape are not particularly limited, but those having a base material diameter of 0.4 mm to 3.0 mm and the like can be preferably used.

It is preferable that the resin composition of the present invention is applied to the surface of the metal conductor and baked to form a thermosetting product which is an insulating film. The coating and baking can be carried out by the same method and conditions as those for forming the insulating film of the known insulated electric wire. The coating and baking treatment may be repeated twice or more. Further, the resin composition of the present invention can be used by blending with other resin paints as long as the gist of the present invention is not impaired.

In the baking of the resin composition of the present invention, the temperature condition and the heating condition can be appropriately determined according to the type of the polyamic acid (A) contained in the resin composition. Trimellitic acid anhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and 2,3,3', 4'-biphenyltetracarboxylic dianhydride were used as the polyamic acid (A). When producing polyamide-imide or polyimide, the transit time is set to 2 to 4 minutes at 300 to 500 ° C. for a natural convection vertical furnace of about 5 m, although it depends on the shape of the furnace. It is preferable to carry out this.

The thickness of the thermosetting product, which is the insulating film, is preferably 1 to 200 μm, more preferably 10 to 100 μm, from the viewpoint of protecting the base material. This is because if the insulating film becomes too thick, the outer diameter of the insulated wire tends to increase, and the space factor of the coil wound with the insulated wire tends to decrease.

Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the Examples as long as the gist of the present invention is not deviated. Unless otherwise specified, parts mean parts by weight and% means% by weight.

[Manufacturing Example 1]
Prepare a flask equipped with a stirrer, nitrogen inflow tube, thermometer, and cooling tube, and as the first-stage synthetic reaction, add 526 parts of trimellitic acid anhydride (TMA) and 9 parts of methanol to N-methyl-2-pyrrolidone. It was dissolved in 1167 parts (NMP, SP value 11.2) and reacted at 60 ° C. for 2 hours. Then, 699 parts of 4,4'-diphenylmethane diisocyanate (MDI) was added and reacted at 140 ° C. for 2 hours, 150 ° C. for 1 hour, and 160 ° C. for 1 hour. After completion of the reaction, the reaction solution was cooled, and 30 parts of benzyl alcohol and 292 parts of N, N-dimethylformamide (DMF) were added to obtain a polyamide-imide precursor (A-1) as a polyamic acid.

[Manufacturing Example 2]
A flask equipped with a stirrer, a nitrogen inflow tube, a thermometer, and a cooling tube was prepared, and 30 parts of trans-1,4-diaminocyclohexane was dissolved in 524 parts of NMP under a nitrogen atmosphere. Next, 62 parts of 3,3', 4,4'-biphenyltetracarboxylic dianhydride and 16 parts of 2,3,3', 4'-biphenyltetracarboxylic dianhydride were added and dissolved at 40 ° C. Stirred until Then, the mixture was stirred for 8 hours to obtain a polyimide precursor (A-2) as a polyamic acid.

[Example 1]
Hollow silica (Godball B6-C number average particle size 3 μm manufactured by Suzuki Yushi Kogyo Co., Ltd., hollow ratio 80 vol%) (B-1) 8 with respect to 100 parts of the polyamide-imide precursor (A-1) obtained in Production Example 1. .9 parts and 0.5 parts of New Pole PE-68 (EO-PO-EO triblock copolymer manufactured by Sanyo Kasei Kogyo Co., Ltd.) (SP value 9.9) (C-1) were added as compound (C). A resin composition (S-1) containing a hollow particle-dispersed polyamide-imide precursor is obtained by stirring for 5 minutes with a stirring defoamer (Sinky Co., Ltd., Awatori Rentaro AR-360M, rotation 600 rpm, revolution 2000 rpm). It was.

[Example 2]
Hollow silica (Polyethylene-110P8 number average particle size 12 μm, hollow ratio 50 vol%) (B-2) 3.81 with respect to 100 parts of the polyimide precursor (A-2) obtained in Production Example 2. Add 0.2 parts of New Pole PE-68 (EO-PO-EO triblock copolymer manufactured by Sanyo Kasei Kogyo Co., Ltd.) (SP value 9.9) (C-1) as part and compound (C), and stir off. A resin composition (S-2) containing a hollow particle-dispersed polyimide precursor was obtained by stirring with a foaming machine (manufactured by Shinky Co., Ltd., Awatori Rentaro AR-360M, rotation 600 rpm, revolution 2000 rpm) for 5 minutes.

[Example 3]
PMMA cross-linked hollow particles (manufactured by Matsumoto Yushi Kogyo Co., Ltd., Matsumoto Microsphere MHB-R, number average particle size 12 μm, hollow ratio 60 vol%) with respect to 100 parts of the polyamide-imide precursor (A-1) obtained in Production Example 1 ( B-4) 5.25 parts and 0.3 part of Emulmin V-100 (manufactured by Sanyo Kasei Kogyo Co., Ltd., oleyl alcohol EO adduct) (C-2) as compound (C) were added, and a stirring defoamer (Shinky Co., Ltd.) Awatori Rentaro AR-360M (manufactured by Awatori Rentaro AR-360M, rotation 600 rpm, revolution 2000 rpm) was stirred for 5 minutes to obtain a resin composition (S-3) containing a hollow particle-dispersed polyamide-imide precursor.

[Example 4]
PMMA crosslinked hollow particles (Techpolymer MBX-3 manufactured by Sekisui Chemical Co., Ltd., number average particle size 3 μm, hollow ratio 40 vol%) (B-5) with respect to 100 parts of the polyimide precursor (A-2) obtained in Production Example 2. ) 2.68 parts and 0.2 parts of Emulmin V-100 (manufactured by Sanyo Kasei Kogyo Co., Ltd., oleyl alcohol EO adduct) (C-2) as compound (C) were added, and a stirring defoamer (manufactured by Shinky Co., Ltd., Awa) A resin composition (S-4) containing a hollow particle-dispersed polyimide precursor was obtained by stirring with Tori Rentaro AR-360M (rotation 600 rpm, revolution 2000 rpm) for 5 minutes.

[Example 5]
PMMA crosslinked hollow particles (three-water hollow polymer particles, number average particle size 0.9 μm, hollow ratio 60 vol%) with respect to 100 parts of the polyimide precursor (A-2) obtained in Production Example 2 (B-6). 2.69 parts and 0.2 parts of Emulmin V-100 (manufactured by Sanyo Kasei Kogyo Co., Ltd., oleyl alcohol EO adduct) (C-2) were added as compound (C), and a stirring defoamer (manufactured by Shinky Co., Ltd., Awatori) was added. A resin composition (S-5) containing a hollow particle-dispersed polyimide precursor was obtained by stirring with Rentaro AR-360M (rotation 600 rpm, revolution 2000 rpm) for 5 minutes.

[Example 6]
9.96 parts of hollow silica (BS-0340 average particle size 3 μm, hollow ratio 40 vol%) (B-3) with respect to 100 parts of the polyamide-imide precursor (A-1) obtained in Production Example 1. And 0.5 part of New Pole PE-68 (EO-PO-EO triblock copolymer manufactured by Sanyo Kasei Kogyo Co., Ltd.) (SP value 9.9) (C-1) was added as compound (C), and the mixture was stirred and defoamed. A resin composition (S-6) containing a hollow particle-dispersed polyamide-imide precursor was obtained by stirring with a machine (manufactured by Shinky Co., Ltd., Awatori Rentaro AR-360M, rotation 600 rpm, revolution 2000 rpm) for 5 minutes.

[Example 7]
Hollow silica (BS-0340 average particle size 3 μm, hollow ratio 40 vol%) (B-3) 3.82 parts with respect to 100 parts of the polyimide precursor (A-2) obtained in Production Example 2. 0.2 part of New Pole PE-68 (EO-PO-EO triblock copolymer manufactured by Sanyo Kasei Kogyo Co., Ltd.) (SP value 9.9) (C-1) was added as compound (C), and a stirring defoamer A resin composition (S-7) containing a hollow particle-dispersed polyamide-imide precursor was obtained by stirring for 5 minutes at (Awatori Rentaro AR-360M, manufactured by Shinky Co., Ltd., rotation 600 rpm, revolution 2000 rpm).

[Comparative Example 1]
In Production Example 1, 9.96 parts of hollow silica (BS-0340 average particle size 3 μm, hollow ratio 40 vol%) (B-3) manufactured by Denki Kagaku Kogyo Co., Ltd. was added to 100 parts of the polyamide-imide precursor (A-1). A resin composition (S'-1) containing a hollow particle-dispersed polyamide-imide precursor was stirred for 5 minutes with a stirring defoamer (Sinky Co., Ltd., Awatori Rentaro AR-360M, rotation 600 rpm, revolution 2000 rpm). Obtained.

<Evaluation of dispersibility in resin composition>
The dispersibility of the hollow particles in the resin compositions (S-1) to (S-7) was evaluated and shown in Table 1. The dispersibility was evaluated by using a laser diffraction / scattering particle size distribution measuring device (LA-920 (manufactured by HORIBA)) to set the refractive index of NMP to 1.47 and the refractive index of silica to 1.44. The number average particle size of the agglomerated particles (secondary particles) was measured and analyzed. The agglomerated particles having a size of 10 times or more the particle size of the hollow particles are all hollow particles in the resin composition. If it is contained in an amount of 10% or more with respect to the number of secondary particles), it is judged that the dispersibility is not preferable. ..

<Evaluation of dispersibility in thermosetting products>
The dispersibility of hollow particles in the thermosetting product was evaluated. A sample obtained by cutting out an ultrathin section having a thickness of 300 nm from a thermocured film (thickness 50 to 200 μm) using an ultramicrotome UC7 (JEOL Ltd.), which is a scanning electron microscope, is placed on a sample table and a vapor deposition apparatus. Pt was vapor-deposited on the sample and observed. Place the stained sample in a scanning electron microscope and magnify it at 10 μA, 15 kV, 5,000 times to observe inorganic hollow particles (including secondary particles) or pores created by melting resin hollow particles. Are observed, 100 of the particles or the pores are arbitrarily selected, the major axis of each is measured, and the number average value is calculated to obtain the number average particle size. The number average particle diameter of the major axis may be calculated by an image analyzer attached to the image of the electron microscope, or 100 major axes of the particles can be measured directly from the image and the number average value can be obtained. Dispersibility is achieved when agglomerated particles having a size 10 times or more the particle size of the hollow particles are contained in an amount of 10% or more based on the total number of hollow particles (including secondary particles) in the thermosetting product. It is judged to be unfavorable. If the dispersibility is poor, the strength of the thermosetting product is reduced and the withstand voltage life is shortened.

<Curing conditions>
The obtained resin composition containing the polyamide-imide precursor {(S-1), (S-3), (S-6), (S'-1)} was applied to a glass substrate, and the temperature was 180 ° C. for 30 minutes. , 300 ° C. for 30 minutes to obtain thermosetting products containing polyimide {(T-1), (T-3), (T-6), (T'-1)}.
Further, the obtained resin composition containing the polyimide precursor {(S-2), (S-4), (S-5), (S-7)} was applied to a glass substrate, and the temperature was 120 ° C. for 1 hour. , 150 ° C. for 30 minutes, 200 ° C. for 30 minutes, 300 ° C. for 20 minutes, thermosetting products containing polyimide {(T-2), (T-4), (T-5), (T) -7)} was obtained.

<Relative permittivity>
A 2 mm × 100 mm test strip, which is a thermosetting product obtained by molding a polyamide-imide precursor or a resin composition containing a polyimide precursor produced in Examples and Comparative Examples into a film, is subjected to a cavity resonator perturbation method. (C8720ES; manufactured by Azilent) was used to measure the dielectric constant at a frequency of 10 GHz. The results are summarized in Table 1.

<Partial discharge voltage>
The polyamide-imide precursor or the resin composition containing the polyimide precursor produced in Examples and Comparative Examples is sandwiched between brass parallel plate electrodes (diameter 30 mm), which is a thermosetting product obtained by molding to a thickness of 100 μm, and alternating current. The voltage was boosted at 0.5 kV / min to charge electricity, and the voltage value at the time when the discharge current was first detected was measured. The results are summarized in Table 1.

<Withstand voltage life>
The thermosetting products produced in Examples and Comparative Examples were molded into a film, sandwiched between brass parallel plate electrodes (diameter 30 mm), boosted from an initial charge of 1 kV to 3 kV at 0.5 kV / min, charged, and short-circuited. The time to complete was measured. The results are summarized in Table 1.

The heat-cured product of the present invention can reduce the dielectric constant by an insulating film, and is an insulated wire, a household appliance, an electric and electronic material, a building material, a printed circuit board, which is a conventional insulated wire and is used for equipment having a high applicable voltage. It can be suitably used in the copper wiring process.

Claims (4)

A resin composition containing a polyamic acid (A), hollow particles (B) having a number average particle diameter of 0.1 to 30 μm, and a compound (C) represented by the following general formula (1) or (3). A resin composition, wherein the volume ratio (vol%) of the hollow particles (B) is 10 to 40 with respect to the total volume of the polyamic acid (A) and the hollow particles (B).

[In the general formula (1), R represents an alkyl group or an alkenyl group having 1 to 24 carbon atoms. A ₁ O is at least one selected from alkyleneoxy groups having 2 to 6 carbon atoms. e is an integer of 1 or more and 100 or less, and when e is 2 or more, a plurality of A ₁ O may be the same or different. − (A ₁ O) _e −H has a terminal group represented by the following general formula (2). ]

[A ₂ O is one selected from alkyleneoxy groups having 2 to 6 carbon atoms, and g is an integer of 1 or more and 100 or less. ]

[In the general formula (3), A ₃ O, A ₄ O and A ₅ O are one selected from alkyleneoxy groups having 2 to 6 carbon atoms, respectively, and are adjacent to each other, A ₃ O and A ₄ O, A. ₄ O and A ₅ O are alkyleneoxy groups having different carbon atoms, and A ₃ O and A ₅ O may be alkylene oxy groups having the same carbon number. h, i and j are integers of 1 or more and 150 or less, respectively, and h + i + j is an integer of 50 or more and 250 or less. The resin composition according to claim 1, wherein the hollow particles (B) are silica particles and / or acrylic resin particles. The thermosetting product of the resin composition according to claim 1 or 2. The method for producing a thermosetting product according to claim 3, which comprises a step of dehydrating and condensing the polyamic acid (A) contained in the resin composition according to claim 1 or 2.