KR20210067644A - Polyamic Acid Composition, Method For Preparing The Same and Polyimide Coating Material Comprising The Same - Google Patents

Abstract

The present invention provides a polyamic acid composition for coating a conductor, as a polyamic acid composition for coating a conductor, which has improved adhesion between the conductor and a material to be coated and improved flexibility of the material to be coated while imparting corona resistance to a cured product.

Description

Polyamic Acid Composition, Method For Preparing The Same and Polyimide Coating Material Comprising The Same

The present invention relates to a polyamic acid composition, a method for preparing the polyamic acid composition, a polyimide comprising the same, and a coating comprising the same.

The insulating layer (coating) which coat|covers a conductor is calculated|required excellent insulation, adhesiveness to a conductor, heat resistance, mechanical strength, etc.

Moreover, in an electric device with a high applied voltage, for example, a motor used at high voltage, a high voltage is applied to the insulated wire which comprises an electric device, and partial discharge (corona discharge) is easy to generate|occur|produce on the covering surface.

The corona discharge may cause a local temperature rise or the generation of ozone or ions, and as a result, deterioration of the insulation of the insulated wire may cause an early insulation breakdown and shorten the life of the electric device.

For insulated wires used at high voltage, an improvement in the corona discharge start voltage is required for the above reasons, and for this purpose, it is known that lowering the dielectric constant of the insulating layer is effective.

Examples of the resin for forming the insulating layer include polyimide resin, polyamideimide resin, polyesterimide resin, and the like.

In general, the polyimide resin refers to a high heat-resistant resin produced by solution polymerization of an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to prepare a polyamic acid derivative, and then imidizing it by ring closure dehydration at a high temperature.

Polyimide resin has excellent heat resistance and a relatively low dielectric constant, and has excellent properties to be used as a material for covering conductors.

However, on the other hand, since the polyimide resin has a rigid structure, it is also true that the elongation at break and flexibility are low, so that it has disadvantageous properties to be used as a conductor coating.

For example, in the coil used for a motor, in order to increase the space factor, after winding an insulated wire and forming a coil, a process which greatly deforms an insulated wire, such as inserting a coil in a slot, may be performed.

At this time, if the flexibility of the insulating layer is low, there is a risk that the coating may be damaged during processing or cracks may occur in the coating.

When a polyimide resin is prepared by reacting diamines and dianhydrides having a flexible structure to improve flexibility, heat resistance is lowered compared to polyimide resins that do not contain diamines or dianhydrides having a flexible structure there is

On the other hand, as described above, when the insulated wire to which a high voltage is applied has insufficient corona resistance characteristics, there is a small gap between the coating and the coating or inside the coating, and partial discharge occurs due to the corona phenomenon in which the electric field is concentrated in that part.

In order to give sufficient corona resistance to an insulated wire, the enameled wire which added inorganic insulation particles, such as silica and titanium dioxide, to a coating resin is known.

In addition to imparting corona resistance to the insulated wire, the inorganic insulating particles may contribute to improvement of thermal conductivity, reduction of thermal expansion and improvement of strength.

However, as the content of the inorganic insulating particles increases, the corona resistance is improved, but the adhesion between the conductor and the coating and the flexibility of the coating may be reduced.

When the flexibility of the coating is lowered, cracks are likely to occur, and when cracks occur, as a result, a problem arises in that the effect of corona resistance, which is the original purpose, cannot be exhibited.

Accordingly, there is a high need for a technology capable of fundamentally solving these problems.

An object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past. The present application can improve the adhesion between the conductor and the coating and the flexibility of the coating while imparting corona resistance.

This application relates to a polyamic acid composition. The polyamic acid composition may be applied for conductor coating. The polyamic acid composition may include a polyamic acid having a molecular weight distribution (Mw/Mn) in the range of 1.6 to 2.5 and inorganic particles treated with at least two different surface treatment agents. The molecular weight distribution may have, for example, a lower limit of 1.63, 1.65, 1.67, 1.7, 1.73, 1.8, 1.83, 1.85, 1.87, 1.90, 1.93 or 1.98 or more, and an upper limit of, for example, 2.4, 2.3, 2.2, 2.1, 2.0, 1.95, 1.90, 1.85 or 1.80 or less. By providing the polyamic acid composition described above, the present application can simultaneously implement adhesiveness, corona resistance, and flexibility of the cured product after curing.

The surface of the inorganic particles may be treated with two or more different surface treating agents, and the two or more kinds of surface treating agents may be different compounds. In one example, the surface treatment agent may include a first surface treatment agent including a functional group capable of bonding with an inorganic material and a second surface treatment agent including a functional group capable of chemical reaction with an organic material. The bonding with the inorganic material may be, for example, a van der Waals bonding. The inorganic material may be a metal. The functional group capable of chemical reaction with the organic material is a general functional group having chemical reactivity. The bond with the inorganic material is reversible, whereas the bond with the organic material is irreversible. The binding force with the inorganic material may be, for example, in the range of 5 to 20KJ/mol, 6 to 18KJ/mol, 7 to 15KJ/mol, 8 to 13KJ/mol, or 10 to 12KJ/mol. The type of the inorganic material is not particularly limited, and may be, for example, a conductor to be described later. The type of the organic material is not particularly limited, and may be, for example, an organic compound, polyamic acid, additive, crosslinking agent, or curing agent included in the polyamic acid composition. The functional group of the second surface treatment agent may be combined with an inorganic material like the functional group of the first surface treatment agent, but in the present specification, if it has a chemically reactive functional group, it may be the second surface treatment agent. Conversely, if there is no chemically reactive functional group in the molecular structure, it may be the first surface treating agent. The functional group of the first surface treatment agent may be, for example, an alkoxy group, and may be an alkoxy group having 1 to 10 or 1 to 5 carbon atoms. In addition, the functional group of the two surface treatment agents may include, for example, a vinyl group, a (meth)acrylic group, a mercapto group, an epoxy group, an amino group, or a thiol group. In this application, by using the two different surface treatment agents, inorganic particles are included to provide corona resistance, improvement of thermal conductivity, reduction of thermal expansion and improvement of strength, while at the same time improving adhesion between conductor and coating and flexibility of coating. can keep

The inorganic particles may have, for example, an average particle diameter in the range of 5 to 80 nm, and in an embodiment, the lower limit may be 8 nm, 10 nm, 15 nm, 18 nm, 20 nm or 25 nm or less, and the upper limit is Yes For example, it may be 70 nm, 60 nm, 55 nm, 48 nm, or 40 nm or less. In the present specification, the average particle size may be measured according to D50 particle size analysis. By controlling the particle size range, the present application improves the compatibility with polyamic acid by implementing the surface treatment degree of the inorganic particles to a desired level, thereby improving corona resistance and maintaining the dielectric breakdown voltage while maintaining adhesion and coating properties. Flexibility can be improved.

The type of the inorganic particles is not particularly limited, but silica, alumina, titanium dioxide, zirconia, yttria, mica, clay, zeolite, chromium oxide, zinc oxide, iron oxide, magnesium oxide, calcium oxide, scandinium oxide or barium oxide may be used. may include In addition, the surface treatment agent may include, for example, a silane coupling agent. The silane coupling agent may be at least two selected from the group consisting of epoxy-based, amino-based and thiol-based compounds, and this may be an example of the second surface treatment agent. Specifically, the epoxy-based compound may include glycidoxypropyl trimethoxysilane (GPTMS), and the amino-based compound is aminopropyltrimethoxysilane ((3-Aminopropyl)trimethoxy-silane: APTMS), and the thiol-based compound may include mercapto-propyl-trimethoxysilane (MPTMS), but is not limited thereto. In addition, the surface treatment agent may include dimethyldimethoxysilane (DMDMS), methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES) or tetraethoxysilane (TEOS), and these surface treatment agents are described above. One first surface treatment agent may be an example. In the present application, the surface of the inorganic particles may be surface-treated using different types of surface treatment agents. In addition, the inorganic particles may be included in the range of 1 to 20 parts by weight based on 100 parts by weight of the polyamic acid. The lower limit of the content may be, for example, 3 parts by weight, 5 parts by weight, 8 parts by weight, 9 parts by weight, or 10 parts by weight or more, and the upper limit is, for example, 18 parts by weight, 15 parts by weight, 13 parts by weight or 8 parts by weight or less. In addition, in the present application, the content ratio of the second surface treatment agent to the first surface treatment agent (ratio of the content of the second surface treatment agent to the content of the first surface treatment agent) is greater than 1, 1.01 or more, 1.02 or more, 1.03 or more, or 1.04 or more. and the upper limit may be 2 or less, 1.5 or less, 1.3 or less, or 1.1 or less. In addition, the first and second surface treatment agents are 0.1 to 50 parts by weight, 1 to 45 parts by weight, 3 to 40 parts by weight, 5 to 30 parts by weight, 10 to 25 parts by weight, or 14 to 50 parts by weight based on 100 parts by weight of the inorganic particles. It may be included in the range of 23 parts by weight. In the present application, by blending the inorganic particles with the polyamic acid composition, dispersibility and miscibility are improved, corona resistance is improved, and at the same time, adhesion and flexibility of the coating can be realized at a desired level.

As described above, the polyamic acid composition of the present application may include a polyamic acid, and the polyamic acid may include a diamine monomer and a dianhydride monomer as polymerized units.

The diamine monomer according to the present invention is, for example, an aromatic diamine, and is classified as follows.

1) 1,4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzo Diamines having one benzene nucleus in structure, such as acid acid (or DABA), and the like, having a relatively rigid structure;

2) 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), diaminodiphenyl ether such as 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl) ) -4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane , 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzanilide, 3,3' -dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine), 2,2'-dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxy Benzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4' -diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone , 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4' -Dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(3- aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodi diamines having two benzene nuclei in structure, such as phenyl sulfoxide and 4,4'-diaminodiphenyl sulfoxide;

3) 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-amino) Phenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (or TPE-Q), 1,4-bis(4-aminophenoxy) Benzene (or TPE-Q), 1,3-bis (3-aminophenoxy) -4-trifluoromethylbenzene, 3,3'-diamino-4- (4-phenyl) phenoxybenzophenone, 3 ,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide) Benzene, 1,4-bis(4-aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis( 4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4- Di having three benzene nuclei in structure, such as bis[2-(4-aminophenyl)isopropyl]benzene

amines; 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4, 4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4-aminophenoxy)phenyl]ether, bis[4-(3 -aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3-(3-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy) Phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis

[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4) -aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy) phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane , bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl] propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4 -(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane Pain, 2,2-bis [3- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3-amino) Phenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3, Diamines having 4 benzene nuclei in structure, such as 3,3-hexafluoropropane.

The said diamine monomer can be used individually or in combination of 2 or more types as needed. In this case, the polyamic acid composition may contain 80 mol% or more, 85 mol% or more, or 90 mol% or more of the flexible diamine monomer including two or more benzene rings in the molecular structure with respect to the entire diamine monomer, and the upper limit is 100 mol% % or 95 mol% or less. In the present invention, by including a flexible diamine monomer having a flexible structure in the molecular structure, the flexibility of the polyimide coating prepared using the polyamic acid composition can be improved, and damage to the coating and cracking of the coating can occur during processing. can solve the problem

In the present specification, the flexible diamine monomer, for example, may refer to a compound in which two benzene rings are not directly connected, but connected via carbon or oxygen, and the carbon is, for example, an alkylene group, an alkylidene group, carbonyl and the like can be exemplified. In one example, the flexible monomer has two benzene rings -O-, -CO-, -NHCO-, -S-, -SO ₂ -, -CO-O-, -CH ₂ - or -C(CH ₂ ) may be a compound linked through _{2 -.}

In one specific example, the flexible diamine monomer is composed of 4,4'-oxydianiline (4,4'-oxydianiline; ODA) and 4,4'-methylenedianiline (4,4'-methylenedianiline; MDA). It may be one or more selected from the group, but is not limited thereto.

On the other hand, the dianhydride monomer that can be used in the preparation of the polyamic acid solution may be an aromatic tetracarboxylic dianhydride, and the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (or a-BPDA), Oxydiphthalic dianhydride (or ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (or DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride Ride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2, 2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimellitic monoester acid anhydride), p-biphenylenebis(trimellitic monoester acid anhydride) Ride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1 ,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-di) Carboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride Ride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride and the like can be exemplified.

The present application also relates to a method for preparing a polyamic acid composition. The manufacturing method may be a method of preparing the above-described polyamic acid composition.

The method for preparing the polyamic acid composition may include dividing at least one of a dianhydride monomer and a diamine monomer twice or more and adding inorganic particles treated with at least two different surface treatment agents.

The polyamic acid composition may be prepared by polymerizing a dianhydride monomer and a diamine monomer in an organic solvent.

In the present application, the polyamic acid composition may include an organic solvent.

The organic solvent is not particularly limited as long as it is an organic solvent in which the polyamic acid can be dissolved, but may be an aprotic polar solvent as an example.

The aprotic polar solvent is, for example, N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), dimethylpropane Amide solvents such as amide (DMPA), phenolic solvents such as p-chlorophenol and o-chlorophenol, N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL) and Diglyme, etc. and these may be used alone or in combination of two or more.

In the present application, the solubility of the polyamic acid may be adjusted by using an auxiliary solvent such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, and water in some cases.

In addition, the dianhydride monomer and the diamine monomer may be added in the form of a powder, a lump, and a solution. At the beginning of the reaction, the dianhydride monomer and the diamine monomer may be added in the form of a powder to proceed with the reaction and added in the form of a solution to control the polymerization viscosity. It is preferable to do

For example, while the dianhydride monomer and the diamine monomer are added in powder form to proceed with the reaction, the dianhydride may be added in the form of a solution to react until the viscosity of the polyamic acid composition reaches a certain range.

The polyamic acid composition of the present application may be a composition having a low viscosity characteristic. The polyamic acid composition of the present application may have a viscosity of 10,000 cP or less and 9,000 cP or less, measured ^{at a temperature of 23° C. and a shear rate of 1s −1 .} The lower limit is not particularly limited, but may be 500 cP or more or 1000 cP or more. The viscosity may be measured using, for example, Rheostress 600 manufactured by Haake, and may be measured at a shear rate of 1/s, a temperature of 23° C., and a plate gap of 1 mm. The present application provides a precursor composition having excellent processability by adjusting the viscosity range, thereby forming a coating having desired properties when coating a conductor wire.

In one specific example, the molecular weight of the polyamic acid may be in the range of 10,000 to 50,000 g/mol or 15,000 to 30,000 g/mol. The weight average molecular weight means a value converted to standard polystyrene measured by gel permeation chromatograph (GPC). In addition, as described above, the polyamic acid of the present application may have a molecular weight distribution (Mw/Mn) in the range of 1.6 to 2.5.

As the molecular weight distribution of the polyamic acid increases, the tensile modulus and heat resistance may decrease, and reliability may be reduced due to an increase in the deviation of the physical properties of the coating. On the other hand, as the molecular weight distribution decreases, the deviation of the physical properties decreases and the coating process for the conductor is stably There are advantages to progress. The present application provides corona resistance, thermal conductivity improvement, thermal expansion reduction and strength improvement by using the polyamic acid having the molecular weight distribution and the above-mentioned surface treatment agent together, while at the same time providing adhesion between the conductor and the coating and flexibility of the coating. can keep

Meanwhile, the present invention is a method for preparing the polyamic acid composition, wherein at least one of a dianhydride monomer and a diamine monomer is added and dissolved in the organic solvent, and at least one of a dianhydride monomer and a diamine monomer is added to the organic solvent. Provided is a method for preparing a polyamic acid composition in which one is divided into two or more times to polymerize polyamic acid, and inorganic particles surface-treated with at least two or more surface treatment agents are added to the organic solvent and stirred.

The equivalent ratio of the dianhydride monomer and the diamine monomer to the dianhydride monomer can be adjusted through the divided input process.

Specifically, at least one of the dianhydride monomer and the diamine monomer may be divided into at least two or more to five or less times.

The present application also relates to a polyimide, which is a cured product of the polyamic acid composition. The polyimide may be a polyimide coating. In one example, the polyimide may be a cured product of the aforementioned polyamic acid composition or a precursor composition prepared by the method for preparing the same.

The present application also relates to coatings. The coating may include polyimide, which is a cured product of the above-described polyamic acid composition. The coating may, for example, be coated and cured on the surface of the conductor. In one example, the coating may include coating a polyamic acid composition on the surface of the conductor; and imidizing the polyamic acid composition coated on the conductor surface. The conductor may be a copper wire made of copper or a copper alloy, but a conductor made of another metal material such as silver wire or various metal-plated wires such as aluminum or tin-plated lead wire may be included as the conductor. The thickness of the conductor and the coating may be in accordance with KS C 3107 standard. The diameter of the conductor may be in the range of 0.3 to 3.2 mm, and the standard film thickness (average value of the maximum film thickness and the minimum film thickness) of the coating is 21 to 194 μm for type 0, 14 to 169 μm for type 1, and 10 to 31 for type 2 μm. The cross-sectional shape of the conductor may be a round wire, a flat wire, a hexagonal wire, or the like, but is not limited thereto.

In an embodiment of the present application, the polyimide may have a breakdown voltage in the range of 9 to 14 kV. The lower limit of the breakdown voltage may be 10 kV, 10.5 kV, 11 kV, 12 kV, 12.5 kV, 13 kV, 13.3 kV, 13.6 kV or more, and the upper limit may be 13 kV, 12 kV, or 11 kV or less. The dielectric breakdown voltage BDV may be measured by a method known in the art. In one example, the breakdown voltage may be measured as follows. A wire coated with the polyamic acid composition is prepared as a specimen, and the specimen is pretreated in an oven at 150° C. for 4 hours, then placed in a pressure vessel, the pressure vessel is filled with 1400 g of refrigerant, and the pressure vessel is heated for 72 hours. After cooling the pressure vessel, the specimens are transferred to an oven at 150° C., held for 10 minutes, and cooled to room temperature. BDV can be measured by connecting both ends of the wire and increasing the AC voltage of the test voltage (60 Hz) nominal frequency between the wire conductors at a constant rate from zero. In one example, the breakdown voltage is, for example, by applying a load and twist according to the IEC 60851 standard to prepare a twisted sample in two lines, and then apply a test voltage between the conductors to measure the voltage at which the insulation film of the sample breaks. it could be

In one example, the polyimide may have a tanδ in the range of 270 to 340°C. The lower limit of the range may be, for example, at least 280 °C, 290 °C, 300 °C, 310 °C, 315 °C, 323 °C or 328 °C, and the upper limit is, for example, 335 °C, 333 °C, 325 °C, 318 °C. , 310 °C, 308 °C, 303 °C, 295 °C, or 288 °C or less. The tanδ may be measured using a TD300 Tan Delta Tester manufactured by DSE to measure the tanδ value of the polyimide coating, which is a cured product of the polyamic acid composition. Specifically, the specimen is connected to the bridge with a conductor as one electrode and a graphite coating as the other, and the temperature of the assembly is increased at a constant rate at ambient temperature to a temperature that gives a clearly defined curve. The temperature is taken through a detector in contact with the sample and the result is plotted as a graph of a linear axis versus temperature and a log or linear axis versus tanδ, from which the tanδ value of the polyimide coating can be calculated.

In addition, in the present application, the polyimide may have a corona resistance index of 8.5 hours or more, 9 hours or more, 9.5 hours or 10 hours or more. The upper limit is not particularly limited, and may be 30 hours or less. The corona resistance index was measured by applying a voltage of 1,000 V (10 kHz sine wave) to the cured polyimide, and measuring the time until a leakage current of 50 mA or more was detected.

On the other hand, in order to indirectly measure the properties of the coating, a polyimide film having a thickness of any one of 15 to 40 μm or about 25 μm can be prepared and evaluated using a polyamic acid having the same composition as the coating, and also The elongation may be 20 to 120%, and these mechanical properties may be similarly exhibited in the coating coated on the electric wire as described above.

The present application may also provide a coated electric wire including a polyimide coating prepared by coating and imidizing the polyamic acid composition on the surface of the electric wire. In one embodiment, the sheathed electric wire is an electric wire; And the polyamic acid composition described above may include a coating imidized on the surface of the electric wire.

In addition, the present application may provide an electronic device including the covered wire.

As described above, the present application can improve the adhesion between the conductor and the coating and the flexibility of the coating while imparting corona resistance to the coating prepared by imidizing the polyamic acid composition.

In addition, the present invention has excellent heat resistance and corona resistance, and can provide a highly reliable insulated wire.

Hereinafter, the present invention will be described in more detail through Examples according to the present invention and Comparative Examples not according to the present invention, but the scope of the present invention is not limited by the Examples presented below.

<Example 1>

726 g of N-methyl-pyrrolidone as a solvent was added to a 1L reactor under a nitrogen atmosphere.

After setting the temperature to 25 ℃, 130.2 g of 4,4'-ODA as a diamine monomer was added and dissolved, and 137.9 g of PMDA as a dianhydride monomer was added in equal amounts three times at 30 minute intervals to obtain polyamic acid. polymerized.

A polyamic acid composition having a weight average molecular weight of 16,000 g/mole and a molecular weight distribution (Mw/Mn) of 1.73 as measured by GPC (Tosoh Corporation, HLC-8220GPC) was prepared.

As a silane coupling agent in the prepared polyamic acid composition, a spherical shape having an average particle diameter of 20 nm was surface-treated with 6.1 g of dimethyl methoxysilane (DMDMS) as a methoxy compound, 3.2 g of GPTMS as an epoxy compound, and 3.2 g of APTMS as an amino compound as a silane coupling agent. A mixed composition was prepared by mixing silica particles in an amount of 5 parts by weight based on 100 parts by weight of the polyamic acid.

<Example 2>

As a diamine monomer, 98.1 g of 4,4'-ODA and 32.4 g of 4,4'-MDA were added, with respect to the total diamine monomer, 75 mol% of 4,4'-ODA and 25 mol% of 4,4'-MDA The same mixed composition as in Example 1 was prepared, except that the weight average molecular weight measured by GPC (Tosoh Corporation, HLC-8220GPC) was 16,500 g/mole and the molecular weight distribution (Mw/Mn) was 1.89.

<Example 3>

As a diamine monomer, 65.4 g of 4,4'-ODA and 64.8 g of 4,4'-MDA were added, and 50 mol% of 4,4'-ODA and 50 mol% of 4,4'-MDA with respect to the entire diamine monomer. The same mixed composition as in Example 1 was prepared, except that the weight average molecular weight measured by GPC (Tosoh Corporation, HLC-8220GPC) was 17,000 g/mole and the molecular weight distribution (Mw/Mn) was 1.81.

<Example 4>

As a diamine monomer, 129.9 g of 4,4'-MDA was added to contain 100 mol% of 4,4'-MDA, and the weight average molecular weight measured by GPC (Tosoh Corporation, HLC-8220GPC) was 17,300 g/mole, molecular weight The same mixed composition as in Example 1 was prepared except that the distribution (Mw/Mn) was 1.92.

<Example 5>

The same mixed composition as in Example 1 was prepared except that the weight average molecular weight measured by GPC (Tosoh Corporation, HLC-8220GPC) was 15,300 g/mole and the molecular weight distribution (Mw/Mn) was 2.01.

<Example 6>

The same mixed composition as in Example 1 was prepared except that the surface-treated average particle diameter 50 nm spherical silica particles were mixed.

<Example 7>

As a silane coupling agent, 6.1 g of dimethyl methoxysilane (DMDMS) as a methoxy compound, 3.2 g of GPTMS as an epoxy compound, and 3.2 g of MPTMS as a thiol compound were mixed with silica particles surface-treated in Example 1 The same mixed composition as described above was prepared.

<Example 8>

As a silane coupling agent, 6.1 g of dimethyl methoxysilane (DMDMS) as a methoxy compound, 2.1 g of GPTMS as an epoxy compound, 2.1 g of APTMS as an amino compound, and 2.1 g of MPTMS as a thiol compound are mixed with silica particles surface-treated. Except for one thing, the same mixed composition as in Example 1 was prepared.

<Example 9>

As a silane coupling agent, spherical silica particles with an average particle diameter of 150 nm surface-treated with 6.1 g of DMDMS as a methoxy compound, 3.2 g of GPTMS as an epoxy compound and 3.2 g of APTMS as an amino compound are mixed in an amount of 10 parts by weight based on 100 parts by weight of polyamic acid. Except that, the same mixed composition as in Example 1 was prepared.

<Example 10>

As a silane coupling agent, spherical silica particles with an average particle diameter of 20 nm surface-treated with 6.1 g of DMDMS as a methoxy compound, 3.2 g of GPTMS as an epoxy compound and 3.2 g of APTMS as an amino compound as a silane coupling agent were mixed in an amount of 21 parts by weight based on 100 parts by weight of polyamic acid. Except, the same mixed composition as in Example 1 was prepared.

<Comparative Example 1>

As a diamine monomer, 134.7 g of 4,4'-ODA was added to contain 100 mol% of 4,4'-ODA, and 139.5 g of PMDA was added as a dianhydride monomer, and the equivalent ratio of the diamine monomer to the dianhydride monomer was 0.95. The same mixture composition as in Example 1 was prepared except that the weight average molecular weight measured by GPC (Tosoh Co., Ltd., HLC-8220GPC) was 9,600 g/mole and the molecular weight distribution (Mw/Mn) was 1.56. did.

<Comparative Example 2>

The dianhydride monomer was added once without dividing, and the weight average molecular weight measured by GPC (Tosoh Co., Ltd., HLC-8220GPC) was 18,000 g/mole, and the molecular weight distribution (Mw/Mn) was 2.54 except that, The same mixed composition as in Example 1 was prepared.

<Comparative Example 3>

A mixed composition was prepared in the same manner as in Example 1, except that silica particles having an average particle diameter of 20 nm, which were not surface-treated with a silane coupling agent, were used.

<Comparative Example 4>

As a silane coupling agent, the same mixed composition as in Example 1 was prepared, except that 5 parts by weight of silica particles having an average particle diameter of 20 nm surface-treated with DMDMS as a methoxy compound alone were mixed in an amount of 5 parts by weight based on 100 parts by weight of polyamic acid.

<Comparative Example 5>

As a silane coupling agent, the same mixed composition as in Example 1 was prepared, except that 3.2 g of GPTMS, an epoxy compound, surface-treated with an average particle diameter of 20 nm spherical silica particles was mixed in an amount of 5 parts by weight based on 100 parts by weight of polyamic acid.

Diamine monomer (mol%) molecular weight distribution silica particle size
(nm) surface treatment agent silica
input
(parts by weight) 4,4'-ODA 4,4'-MDA Example 1 100 0 1.73 20 M/E/A 5 Example 2 75 25 1.89 20 M/E/A 5 Example 3 50 50 1.81 20 M/E/A 5 Example 4 0 100 1.92 20 M/E/A 5 Example 5 100 0 2.01 20 M/E/A 5 Example 6 100 0 1.73 50 M/E/A 5 Example 7 100 0 1.73 20 M/E/T 5 Example 8 100 0 1.73 20 M/E/A/T 5 Example 9 100 0 1.73 150 M/E/A 10 Example 10 100 0 1.73 20 M/E/A 21 Comparative Example 1 100 0 1.56 20 M/E/A 5 Comparative Example 2 100 0 2.54 20 M/E/A 5 Comparative Example 3 100 0 1.73 20 - 5 Comparative Example 4 100 0 1.73 20 M 5 Comparative Example 5 100 0 1.73 20 E 5

* In the surface treatment agent of Table 1, M is DMDMS, E is GPTMS, A is APTMS, and T is MPTMS.

Experimental Example 1: Viscosity evaluation

For the mixed compositions prepared in Examples and Comparative Examples, each had a solid content of 25%, and the viscosity was measured using a Brookfield viscometer at a shear rate of 1/s, a temperature of 23° C., and a plate gap of 1 mm. and the results are shown in Table 2 below.

Experimental Example 2: Storage stability evaluation

After polymerization, the viscosity change was measured at room temperature (23°C) after 7 days.

Viscosity change = first viscosity - second viscosity (One)

Here, the first viscosity is the viscosity of the compositions of Examples and Comparative Examples at 23°C, and the second viscosity is the viscosity after 7 days at 23°C.

viscosity (poise) storage stability
(±%) Example 1 30 +3 Example 2 30 +5 Example 3 35 +8 Example 4 40 +9 Example 5 60 +8 Example 6 60 +8 Example 7 60 +8 Example 8 60 +8 Example 9 40 +5 Example 10 40 +5 Comparative Example 1 20 -12 Comparative Example 2 160 +20 Comparative Example 3 40 +5 Comparative Example 4 40 +5 Comparative Example 5 40 +5

Preparation of polyimide coatings

In the coating curing furnace, the polyamic acid solution was applied to a copper wire having a conductor diameter of 1 mm with a coating thickness of 2 to 6 μm per one time, and the minimum and maximum temperatures of the coating curing furnace were adjusted to 350 to 550 ° C. An electric wire (coated electric wire) including a polyimide coating having a coating thickness of 33 to 35 μm was prepared in a state where the coating speed was adjusted to 12 to 32 m/min.

<Experimental Example 1: Pinhole Test>

A pinhole test was performed to check whether there was any defect in the insulation of the polyimide coating of the electric wire. Specifically, a wire specimen having a length of about 1.5 m was taken and placed in an air circulation oven (125° C.) for 10 minutes, and then cooled at room temperature without any bending or stretching. The cooled wire specimen was immersed in sodium chloride electrolyte solution to which phenolphthalein alcohol was added while it was connected to an electric circuit having a DC test voltage, and then the number of pinholes was visually checked.

<Experimental Example 2: Evaluation of Thermal Shock Resistance>

Thermal shock resistance was evaluated for the polyimide coating of the electric wire manufactured in Examples and Comparative Examples. Thermal shock resistance is an indicator of whether a wire can withstand temperature exposure in an extended state or wound or bent around a mandrel.

Specifically, in order to evaluate the thermal shock resistance, the polyimide coating of the wires prepared in Examples and Comparative Examples was heated at 200° C. for 30 minutes, removed from the oven, the specimen was cooled to room temperature, and then polyimide at 20% elongation. The number of cracks in the coating was determined and the results are shown in Table 3 below.

<Experimental Example 3: Pull test>

With respect to the polyimide coating of the electric wire prepared in Examples and Comparative Examples, a pulling test was performed to confirm the adhesion between the conductor and the coating, and the results are shown in Table 3 below.

Specifically, a straight wire specimen with a free measuring length of 200 to 250 mm is rapidly stretched to the point of break or elongation (20%) given in the applicable standard. After stretching, inspect the specimen for any loss of adhesion or cracks at the specified magnification (1 to 6 times). The 2 mm length of the broken wire end shall be neglected.

Three specimens are tested. Record the number of cracks and/or loss of adhesion in the wire.

<Experimental Example 4: tan δ value>

For each of the wires manufactured in Examples and Comparative Examples, tan δ values were measured using DSE's TD900 Tan Delta Tester.

Specifically, the specimen is connected to the bridge with a conductor as one electrode and a graphite coating as the other, and the temperature of the assembly is increased at a constant rate at ambient temperature to a temperature that gives a clearly defined curve. The temperature is taken through a detector in contact with the sample and the result is plotted as a graph of a linear axis versus temperature and a logarithmic or linear axis versus tan δ, from which the tan δ value of the polyimide coating is calculated and the result is Table 3 shows.

<Experimental Example 5: BDV evaluation>

The specimens prepared in Examples and Comparative Examples were pretreated in an oven at 150° C. for 4 hours, and then placed in a pressure vessel. The pressure vessel is filled with 1400 g of refrigerant, the pressure vessel is heated for 72 hours, then the pressure vessel is cooled, the specimen is transferred to an oven at 150° C., held for 10 minutes, and cooled to room temperature. BDV was measured by connecting both ends of the wire and increasing the AC voltage of the nominal frequency of the test voltage (60 Hz) between the wire conductors at a constant rate from zero.

<Experimental Example 6: Evaluation of partial discharge initiation voltage (PDIV)>

The voltage at which partial discharge starts was measured by applying a voltage having a 60 Hz sine wave at room temperature to the flat wire wound specimen according to each of Examples and Comparative Examples. Here, if the voltage at which the amount of charge of 100 pC or more is detected is less than 1,000 V when the applied voltage is increased, the specification fails.

<Experimental Example 7: Evaluation of Corona Resistance>

For the coating of the wires prepared in Examples and Comparative Examples, 1,000 V voltage (10 kHz sine wave) was applied to the specimen according to each of Examples and Comparative Examples, and the time until leakage current of 50 mA or more was detected measured.

<Experimental Example 8: Evaluation of film flaws>

In accordance with the standard JIS C 3003, section 7.1.2, film flaw evaluation was performed on the flat wire wound specimens according to Examples and Comparative Examples, respectively. Specifically, cracks occurred among three specimens bent with a mandrel having a diameter (3W) that was three times the conductor width (W) and three specimens bent with a mandrel having a diameter (3T) that was three times the conductor height (T). Otherwise, it is a failure.

pinhole
(Count) 20% tension
crack
(Count) after pulling
crack
(Count) tanδ
(℃) BDV
(kV) Partial discharge start voltage corona
tolerance index
(hour) film flaw Example 1 0 0 0 330 14 pass ≥10 pass Example 2 0 0 0 315 12 pass ≥10 pass Example 3 0 0 0 320 11 pass ≥10 pass Example 4 0 One One 275 9 pass ≥10 pass Example 5 0 0 0 315 12 pass ≥10 pass Example 6 0 0 One 295 12 pass ≥10 pass Example 7 0 0 0 300 12 pass ≥10 pass Example 8 0 0 0 300 13 pass ≥10 pass Example 9 7 12 8 250 7 fail 3 fail Example 10 3 10 12 265 8 pass ≥10 fail Comparative Example 1 2 3 3 260 8 fail 8 pass Comparative Example 2 13 7 15 260 6 fail 3 fail Comparative Example 3 8 5 4 255 7 fail One fail Comparative Example 4 7 5 3 260 7 fail 5 fail Comparative Example 5 5 2 One 265 8 fail 2 fail

Claims (19)

A molecular weight distribution (Mw / Mn) comprising a polyamic acid in the range of 1.6 to 2.5 and inorganic particles treated with at least two different surface treatment agents,
The polyamic acid composition for coating a conductor, wherein the surface treatment agent includes a first surface treatment agent including a functional group capable of bonding with an inorganic material and a second surface treatment agent including a functional group capable of chemical reaction with an organic material. The polyamic acid composition for coating a conductor according to claim 1, wherein the inorganic particles have an average particle diameter in the range of 5 to 80 nm. The polyamic acid composition for coating a conductor according to claim 1, wherein the inorganic particles are included in an amount of 1 to 20 parts by weight based on 100 parts by weight of the polyamic acid. According to claim 1, wherein the inorganic particles include silica, alumina, titanium dioxide, zirconia, yttria, mica, clay, zeolite, chromium oxide, zinc oxide, iron oxide, magnesium oxide, calcium oxide, scandinium oxide or barium oxide A polyamic acid composition for conductor coating. The polyamic acid composition for coating a conductor according to claim 1, wherein the first surface treatment agent contains an alkoxy group. The polyamic acid composition for coating a conductor according to claim 1, wherein the second surface treatment agent includes a vinyl group, a (meth)acrylic group, a mercapto group, an epoxy group, an amino group, or a thiol group. The polyamic acid composition for coating a conductor according to claim 1, wherein the content ratio of the second surface treatment agent to the first surface treatment agent is greater than 1. The polyamic acid composition for coating a conductor according to claim 1, wherein the polyamic acid comprises a diamine monomer and a dianhydride monomer as polymerized units. The polyamic acid composition for coating a conductor according to claim 8, comprising 80 mol% or more of a flexible diamine monomer having two or more benzene rings in its molecular structure with respect to the entire diamine monomer. 10. The method of claim 9, wherein the soft diamine monomer is selected from 4,4'-oxydianiline (4,4'-oxydianiline; ODA) and 4,4'-methylenedianiline (4,4'-Methylenedianiline; MDA) A polyamic acid composition for coating a conductor comprising at least one monomer used as The method of claim 1, wherein the dianhydride monomer is pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), benzophenonetetracarboxylic dianhydride A polyamic acid composition for coating a conductor comprising at least one monomer selected from the group consisting of (benzophenonetetracarboxylic dianhydride; BTDA) and oxydiphthalic anhydride (ODPA). A method for producing a polyamic acid composition for coating a conductor, comprising the steps of dividing at least one of a dianhydride monomer and a diamine monomer two or more times and adding inorganic particles treated with at least two different surface treatment agents. [13] The method of claim 12, wherein at least one of the dianhydride monomer and the diamine monomer is divided into two or more to ten or less times. A polyimide coating comprising a cured product of the polyamic acid composition according to claim 1 . 15. The polyimide coating according to claim 14, wherein the breakdown voltage (BDV) is 9 to 14 kV. 15. The polyimide coating according to claim 14, wherein the polyimide coating has a corona resistance index of at least 8.5 hours. 15. Polyimide coating according to claim 14, wherein the tan δ is in the range of 270 to 340°C. An electric wire comprising the polyimide coating according to claim 14 . An electronic device comprising a wire according to claim 18 .