WO2020091147A1 - Conductor-coating polyimide varnish for improving heat resistance of polyimide-coated product, and polyimide-coated product manufactured therefrom - Google Patents

Abstract

The present invention provides a conductor-coating polyimide varnish comprising: a polyamic acid solution to be prepared by the polymerization of one or more types of dianhydride monomers and one or more types of diamine monomers in an organic solvent; a silicone-based additive; an alkoxysilane coupling agent; and a low-temperature curing agent, wherein the softening resistance temperature of a coated product manufactured from the polyimide varnish is 500°C or higher.

Description

Polyimide varnish for conductor coating to improve the heat resistance of polyimide coatings and polyimide coatings prepared therefrom

The present invention relates to a polyimide varnish for conductor coating for improving the heat resistance of a polyimide coating and a polyimide coating prepared therefrom.

The insulating layer (insulating coating) covering the conductor is required to have excellent insulation, adhesion to the conductor, heat resistance, mechanical strength, and the like.

In addition, in an electric device having a high applied voltage, such as a motor used at a high voltage, a high voltage is applied to an insulated wire constituting the electric device, and partial discharge (corona discharge) is likely to occur on the surface of the insulating coating.

The occurrence of corona discharge may cause local temperature rise or generation of ozone or ions. As a result, deterioration in the insulation coating of the insulated wire may cause premature insulation destruction and shorten the lifespan of electrical equipment. .

For the above reasons, an improvement in the corona discharge start voltage is required for an insulated wire used as a high voltage, and for this purpose, it is known that it is effective to lower the dielectric constant of the insulating layer.

Examples of the resin that can be used for the insulating layer include polyimide resin, polyamideimide resin, and polyesterimide resin.

Among them, in particular, polyimide resin is a material having excellent heat resistance and insulation properties, and has excellent properties for use as a material for coating a conductor.

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 produce a polyamic acid derivative, followed by dehydration at high temperature by ring dehydration.

As a method of forming an insulating coating using such a polyimide resin, for example, a polyimide varnish, which is a precursor of a polyimide resin, is coated or coated around an electric wire made of a conductor, and then a curing furnace capable of heat treatment at a predetermined temperature. The method of imidizing the polyimide varnish within can be used.

The method of forming the insulating coating may cause a difference in physical properties, productivity and manufacturing cost of the insulating coating prepared according to conditions such as the temperature of the curing furnace, the number of coating times of the polyimide varnish, and the coating speed. That is, forming an insulating coating at a high temperature may be advantageous for producing an insulating coating having excellent physical properties, and productivity may increase as the number of coatings is small or the coating speed is fast.

However, if the temperature of the curing furnace is too high, a defect may occur on the surface of the insulating coating to be produced or a problem of carbonization of the polyimide resin may occur, and if the number of coatings is too small or the coating speed is too fast, it is produced. A problem that the physical properties of the polyimide coating is lowered may occur.

In addition, since the general polyimide resin has excellent adhesion to a conductor despite excellent physical properties, a problem in appearance defects may occur when forming an insulating coating.

As described above, there are many difficulties in improving the properties required for the polyimide varnish and the polyimide resin prepared therefrom. In particular, when improving one property, it is common for other properties to be lowered, and thus satisfying several properties at the same time. This is a subject that is constantly being researched in the related technical field.

Therefore, there is a high need for a polyimide varnish for coating a conductor having excellent productivity and process efficiency, excellent heat resistance, insulation properties and mechanical properties of the polyimide, and excellent adhesion to the conductor.

An object of the present invention is to provide a polyimide varnish for coating a conductor comprising a surface modifier, a coupling agent and a curing agent and a polyimide coating prepared therefrom.

According to one aspect of the present invention, surface modifiers, coupling agents and curing agents are disclosed as essential factors for the implementation of polyimide coatings having excellent heat resistance, insulation, flexibility and adhesion to a substrate (conductor).

Accordingly, the present invention has a practical purpose to provide a specific embodiment thereof.

The present invention is a polyimide varnish for conductor coating,

A polyamic acid solution prepared by polymerizing one or more dianhydride monomers and one or more diamine monomers in an organic solvent;

Silicone-based additives;

Alkoxy silane coupling agents; And

Contains a low temperature curing agent,

Provided is a polyimide varnish having a softening resistance of 500 ° C or higher of the coating prepared from the polyimide varnish.

When the polyimide coating was prepared using the polyimide varnish, it was found that it has excellent heat resistance and insulation, and the flexibility of the coating and adhesion to the substrate are improved.

Therefore, specific details for its implementation will be described herein.

Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to ordinary or lexical meanings, and the inventor appropriately explains the concept of terms to explain his or her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

Therefore, the configuration of the embodiments described herein is only one of the most preferred embodiments of the present invention and does not represent all of the technical spirit of the present invention, and various equivalents and modifications that can replace them at the time of this application It should be understood that examples may exist.

In the present specification, a singular expression includes a plural expression unless the context clearly indicates otherwise. In this specification, the terms "include", "have" or "have" are intended to indicate the presence of implemented features, numbers, steps, elements or combinations thereof, one or more other features or It should be understood that the existence or addition possibilities of numbers, steps, elements, or combinations thereof are not excluded in advance.

As used herein, "dianhydride (dianhydride)" is intended to include its precursors or derivatives, which may not technically be dianhydrides, but nevertheless react with diamines to form polyamic acids. And this polyamic acid can be converted back to polyimide.

“Diamine” as used herein is intended to include precursors or derivatives thereof, which may not technically be diamines, but will nevertheless react with dianhydrides to form polyamic acids, which polyamic acids are again polydi Can be converted to mead.

Where an amount, concentration, or other value or parameter herein is given as an enumeration of ranges, preferred ranges, or preferred upper and lower limits, any upper limit of any pair of any pair, regardless of whether the ranges are disclosed separately or It should be understood to specifically disclose all ranges formed of preferred values and any lower range limits or preferred values.

When a range of numerical values is referred to herein, unless stated otherwise, that range is intended to include the endpoints and all integers and fractions within the range.

It is intended that the scope of the invention not be limited to the specific values recited when defining a range.

First aspect: polyimide varnish

The polyimide varnish according to the present invention is a polyimide varnish for conductor coating,

A polyamic acid solution prepared by polymerizing one or more dianhydride monomers and one or more diamine monomers in an organic solvent;

Silicone-based additives;

Alkoxy silane coupling agents; And

Contains a low temperature curing agent,

It characterized in that the coating made from the polyimide varnish has a softening resistance of 500 ° C or higher.

In one specific example, the degree of softening of the coating made from the polyimide varnish may be 500 ° C or more and 900 ° C or less.

Meanwhile, the polyimide varnish may have a solid content of 15 to 38% by weight, specifically 18 to 38% by weight based on the total weight of the polyimide varnish, and a viscosity at 23 ° C of 500 to 8,000 cP, in detail 500 to 5,000 cP.

When the solid content of the polyimide varnish exceeds the above range, the viscosity of the polyimide varnish is inevitably increased, which is not preferable.

Conversely, when the solid content of the polyimide varnish is less than the above range, a problem that an increase in manufacturing cost and process time may occur as a large amount of solvent must be removed during the curing process.

In addition, the polyimide varnish having the viscosity has an advantage of easy handling in terms of fluidity, and may be advantageous in a process of coating on the conductor surface.

Specifically, when the viscosity of the polyimide varnish exceeds the above range, the process cost is required because a higher pressure must be applied by friction with the pipe when the polyimide varnish is moved through the pipe during the polyimide manufacturing process. This increases and handling can be deteriorated.

In addition, it may be difficult to uniformly coat the polyimide coating on the conductor during manufacture.

On the other hand, when the viscosity of the polyimide varnish is less than the above range, a problem that an increase in manufacturing cost and process time may occur as a large amount of solvent must be removed in the curing process.

It may include 0.01 to 0.05 parts by weight of an alkoxy silane coupling agent with respect to 100 parts by weight of the solid content of the polyimide varnish.

When the content of the alkoxy silane coupling agent exceeds the above range, mechanical properties may be deteriorated, and when heat treatment for imidization, the alkoxy silane coupling agent decomposes at a high temperature to decrease the adhesion between the polyimide coating and the conductor rather. It is not desirable because it can be done.

On the other hand, when the content of the alkoxy silane coupling agent is less than the above range, it is not preferable because the effect of improving the adhesion between the polyimide coating and the conductor cannot be sufficiently exhibited.

The alkoxy silane coupling agent is, for example, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl methyl dimethoxysilane, 3-aminopropyl methyl diethoxysilane, 3- (2 -Aminoethyl) aminopropyl trimethoxysilane, 3-phenylaminopropyl trimethoxysilane, 2-aminophenyl trimethoxysilane, and 3-aminophenyl trimethoxysilane. It can, but is not limited to this.

The polyimide varnish may contain 0.01 to 0.05 parts by weight of a silicone-based additive with respect to 100 parts by weight of solids.

When the content of the silicone-based additive exceeds the above range, the mechanical properties of the polyimide coating to be produced may be deteriorated, and when the heat treatment for imidization, the silicone-based additive is decomposed at a high temperature to improve adhesion between the polyimide coating and the conductor. Rather, it is not preferable because it may decrease.

On the other hand, when the content of the silicone-based additive is less than the above range, it is not preferable because the effect of improving the adhesion between the polyimide coating and the conductor to be produced cannot be sufficiently exhibited.

The silicone-based additives include, for example, dimethylpolysiloxane, polyether modified polydimethysiloxane polymethylalkylsiloxane, hydroxyl group (-OH) and double bond structure (C = C). It may include one or more selected from the group consisting of silicone additives, but is not limited thereto.

The polyimide varnish may include 0.1 to 2 parts by weight of a low temperature curing agent relative to 100 parts by weight of the solid content.

The low temperature curing agent may include at least one selected from the group consisting of betapicoline, isoquinoline, triethylenediamine and pyridine.

Specifically, the low temperature curing agent may include at least one selected from the group consisting of beta-picoline, isoquinoline and pyridine, and triethylenediamine.

In particular, the triethylenediamine serves to enable low temperature curing of the polyimide varnish and to improve the heat resistance of the prepared polyimide coating.

When the content of the low-temperature curing agent exceeds the above range, there is a high possibility of appearance defects due to an increase in the curing rate, and physical properties such as heat resistance, insulation, and flexibility of the polyimide coating are lowered due to differences in local curing rates. Can be. Conversely, when the content of the low-temperature curing agent is less than the above range, it is not preferable because the effect of the present invention for improving the heat resistance of the polyimide coating cannot be sufficiently exhibited.

On the other hand, in general, polyimide resins undergo chemical changes, ie oxidation reactions, in the presence of oxygen by light, heat, pressure, shear force, and the like. This oxidation reaction causes a problem of deteriorating the heat resistance and mechanical properties of the polyimide resin produced by generating a change in physical properties by cutting, crosslinking, etc. of the molecular chain in the polyimide resin.

In the present invention, the polyimide varnish may further solve the problem by further including an antioxidant. Specifically, the antioxidant may have a 5% by weight decomposition temperature of 380 ° C or higher, and specifically, a 5% by weight decomposition temperature of 400 ° C or higher.

The antioxidant may include a compound represented by Formula 1 below.

(One)

In Chemical Formula 1, R ₁ to R ₆ may each independently be selected from the group consisting of C1-C3 alkyl groups, aryl groups, carboxylic acid groups, hydroxy groups, fluoroalkyl groups, and sulfonic acid groups,

n is an integer from 1 to 4,

When R ₁ to R ₆ are plural, they may be the same or different from each other,

m1 to m6 are each independently an integer of 0 to 3.

In Formula 1, when the substituent of the benzene ring is not specifically designated, it means hydrogen.

In one specific example, n in Formula 1 may be 1, m1 to m6 may be 0, and more specifically, the antioxidant may be a compound of Formula 1-1.

(1-1)

Since these antioxidants have low volatility and excellent thermal stability, they do not decompose or volatilize during the manufacturing process of the polyimide coating, and thus can exert an effect of preventing oxidation of the amide group in the polyimide varnish or the imide group of the polyimide coating. have.

Conversely, in the case of an antioxidant having a 5 wt% decomposition temperature of 380 ° C. or less, the polyimide coating is decomposed by high temperature during the manufacturing process, and thus, an effect of introducing the above antioxidant cannot be exhibited.

The antioxidant may be included in the range of 0.1 to 2 parts by weight based on 100 parts by weight of the solid content of the polyimide varnish.

When the content of the antioxidant exceeds the above range, deposition or blooming occurs in the polyimide coating, which may degrade mechanical properties, and may cause defects in the appearance of the coating, which is not preferable.

Conversely, when the content of the antioxidant is less than the above range, it is not preferable because the antioxidant effect cannot be sufficiently exhibited.

Meanwhile, as described above, the polyamic acid solution may be produced by polymerization of one or more dianhydride monomers and one or more diamine monomers.

The dianhydride monomer that can be used in the production of the polyamic acid of the present invention may be an aromatic tetracarboxylic dianhydride.

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, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3- Hexafluoropropane dianhydride, 2,3,3 ', 4'-benzophenonetetracarboxylic 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 (trimeric monoester) No acid Idride), p-biphenylenebis (trimeric monoester acid anhydride), 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-dicarboxy Phenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) biphenyl dianhydride, 2,2-bis [(3,4-dicarboxy phenoxy) phenyl] propane dian Hydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4 '-(2,2-hexafluor And roisopropylidene) diphthalic acid dianhydride. These can be used alone or in combination of two or more as desired.

These may be used alone or in combination of two or more kinds as desired, but the dianhydride monomers that can be particularly preferably used in the present invention include pyromellitic dianhydride (PMDA) and 3,3 ', It may be one or more selected from the group consisting of 4,4'-biphenyltetracarboxylic dianhydrid (BPDA).

The diamine monomers that can be used in the production of the polyamic acid solution of the present invention are aromatic diamines, and are 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 the structure, such as diacid (or DABA), etc., which have a relatively rigid structure in diamine;

2) Diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or oxidianiline, ODA) and 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (Or methylenedianiline, MDA), 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'-diamino Diphenylmethane, 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 '-Dimethoxybenzidine, 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'-diaminodiphenylsulfoxide, 4,4'-dia Diamine having two benzene nuclei in structure, such as minodiphenyl 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- Bis [2- (4-aminophenyl) isopropyl] benzene, which has three benzene nuclei in structure Amine;

4) 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 Si) 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-ami) Phenoxy) 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, 2,2-bis [3- (4 -Aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1, 3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, etc., Diamine having four benzene nuclei in structure.

These can be used alone or in combination of two or more kinds as desired, but the diamine monomers that can be particularly preferably used in the present invention include 4,4'-diaminodiphenyl ether (or oxydianiline, ODA) and 4 , 4'-methylenedianiline (MDA).

Second aspect: a method for producing a polyimide varnish

Method for producing a polyimide varnish according to the present invention,

(a) polymerizing one or more dianhydride monomers and one or more diamine monomers in an organic solvent to prepare a polyamic acid solution; And

(b) a process of mixing a silicone-based additive, an alkoxy silane coupling agent, and a low temperature curing agent in the polyamic acid solution.

Preparation of a polyamic acid solution in the present invention, for example,

(1) A method in which the total amount of the diamine monomer is placed in a solvent, and then the dianhydride monomer is added to be substantially equimolar with the diamine monomer, followed by polymerization;

(2) a method in which the total amount of the dianhydride monomer is placed in a solvent, and then the diamine monomer is added to be substantially equimolar with the dianhydride monomer to polymerize;

(3) After adding some components of the diamine monomer in a solvent, after mixing some components of the dianhydride monomer with respect to the reaction component at a ratio of about 80 to 120 mol%, the remaining diamine monomer components are added and subsequently the rest A method of adding a dianhydride monomer component to polymerize the diamine monomer and the dianhydride monomer to be substantially equimolar;

(4) After placing the dianhydride monomer in a solvent, some components of the diamine compound with respect to the reaction component are mixed at a ratio of 90 to 110 mol%, and then another dianhydride monomer component is added and the rest of the diamine monomer component is continued. And a method in which the diamine monomer and the dianhydride monomer are substantially equimolar and polymerized;

(5) Some of the diamine monomer component and some of the dianhydride monomer component are reacted in an excess amount to form a first composition, and some of the diamine monomer component and some of the dianhydride monomer component are formed in another solvent. After the reaction is carried out so that the excess is formed to form a second composition, the first and second compositions are mixed and polymerization is completed. At this time, if the diamine monomer component is excessive when forming the first composition, the second composition In the dianhydride monomer component in excess, in the first composition when the dianhydride monomer component is excessive, in the second composition, the diamine monomer component in excess, the first and second compositions are mixed and used in these reactions So that the total diamine monomer component and the dianhydride monomer component become substantially equimolar It can be joined to the methods.

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

Non-limiting examples of the aprotic polar solvent include amide solvents such as N, N'-dimethylformamide (DMF) and N, N'-dimethylacetamide (DMAc), p-chlorophenol, and o-chloro And phenol-based solvents such as phenol, N-methyl-pyrrolidone (NMP), gamma brotirolactone (GBL) and digrime, and these may be used alone or in combination of two or more.

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

In one example, organic solvents that can be particularly preferably used in the preparation of the polyimide varnish of the present invention may be amide-based solvents N, N'-dimethylformamide and N, N'-dimethylacetamide.

The polymerization method is not limited to the above examples, and it is needless to say that any known method can be used.

The dianhydride monomer may be appropriately selected from the examples described above, and in detail, pyromellitic dianhydride (PMDA) and 3,3 ', 4,4'-biphenyltetracarboxylic One or more selected from the group consisting of dianhydrides (BPDA, biphenyl-tetracarboxylic dianhydrid) can be preferably used.

The diamine monomer may be appropriately selected from the examples described above, and specifically, composed of 4,4'-diaminodiphenyl ether (or oxydianiline, ODA) and 4,4'-methylenedianiline (MDA). One or more selected from the group can be preferably used.

The process (a) is performed at 30 to 80 ° C, and the polyamic acid solution may have a viscosity at 23 ° C in the range of 500 to 9,000 cP.

In addition, the process (b) may further be performed by mixing an antioxidant in a polyamic acid solution and at 40 to 90 ° C.

The silicone-based additive and the alkoxy silane coupling agent included in the polyimide varnish can improve the adhesion between the polyimide coating and the conductor prepared therefrom, and the antioxidant included in the polyimide varnish is the polyimide coating prepared therefrom Changes in physical properties can be minimized.

In addition, the low-temperature curing agent included in the polyimide varnish can improve physical properties such as heat resistance, insulation, and flexibility of the polyimide coating prepared therefrom.

However, the physical properties of the polyimide coating may be changed even with a specific combination of the silicone-based additive, alkoxy silane coupling agent, antioxidant, and low temperature curing agent and slight content difference included in the polyimide varnish, and it is not easy to predict the change. .

Third aspect: Method for producing polyimide coating and polyimide coating

Method for producing a polyimide coating according to the present invention,

(1) the process of coating the polyimide varnish on the surface of the conductor; And

(2) imidizing the polyimide varnish coated on the conductor surface,

The above processes (1) and (2) are continuously repeated 4 to 20 times,

It characterized in that the polyimide coating has a softening resistance of 500 ° C or higher.

The thickness of the polyimide varnish coated per repetition of the above steps (1) and (2) is 2 to 6 μm,

The process (2) can be carried out at 300 to 750 ℃.

In addition, the coating speed of the conductor may be 2 to 30 m / min.

The conductor may be a copper wire made of copper or a copper alloy, but a conductor made of another metal material such as a silver wire or various metal plating wires such as aluminum and tin-plated wire may also be included as conductors.

The cross-sectional shape of the conductor may be a circular line, a flat angle line, a hexagonal line, etc., but is not limited thereto.

In the production method of the present invention, the polyimide coating may be prepared through thermal imidization.

The thermal imidization method is a method of excluding chemical catalysts and inducing an imidization reaction with a heat source such as hot air or an infrared dryer.

The thermal imidization method may heat the polyimide varnish at a variable temperature in the range of 100 to 750 ° C to imidize the amic acid group present in the polyimide varnish, specifically 300 to 750 ° C, and more specifically Can be imidized by heat treatment at 500 to 700 ° C to amic acid groups present in the polyimide varnish.

The polyimide coating of the present invention manufactured according to the above-described manufacturing method has a thickness in the range of 16 to 50 μm, a softening resistance of 500 ° C. or higher, a tanδ of 270 ° C. or higher, and an insulation breakdown voltage (BDV) of 8 kV / mm. It may be abnormal.

The present invention can also provide an electric wire including a polyimide coating prepared by coating and imidizing the polyimide varnish on the surface of the electric wire, and providing an electronic device including the electric wire.

Hereinafter, the operation and effects of the invention will be described in more detail through specific examples of the invention. However, these examples are only presented as examples of the invention, and the scope of the invention is not thereby determined.

The abbreviated compound names used in Examples and Comparative Examples are as follows.

-Pyromelitic dianhydride: PMDA

-Biphenyltetracarboxylic dianhydride: BPDA

-Oxydianiline: ODA

-Methylenedianiline: MDA

-N-methyl pyrrolidone: NMP

<Example 1>

While nitrogen was injected into a 500 ml reactor equipped with a stirrer and a nitrogen injection / discharge tube, NMP was introduced, and the temperature of the reactor was set to 30 ° C, and then ODA and PMDA were introduced to confirm complete dissolution.

After heating the mixture to a temperature of 50 ° C. under a nitrogen atmosphere and stirring was continued for 120 minutes, a polyamic acid solution having a viscosity at 23 ° C. of 10,000 cP was prepared.

After setting the temperature of the reactor to 50 ° C, OFS-6011 as an alkoxy silane coupling agent in the polyamic acid solution, 5% by weight as an antioxidant, a compound of Formula 1-1 having a decomposition temperature of about 402 ° C, BYK- as a silicone-based additive 378, triethylenediamine as a low temperature curing agent was added at a weight ratio of 1: 50: 1: 1 and slowly stirred for 30 minutes to add NMP such that the total solid content was about 25% by weight and the viscosity was about 3,000 cP. The polyanyl having a molar ratio of dianhydride monomer of 100: 100, 0.01 parts by weight of an alkoxy silane coupling agent, 0.5 parts by weight of an antioxidant, 0.01 parts by weight of a silicone-based additive, and 0.5 parts by weight of a low temperature curing agent based on 100 parts by weight of solid content Mid varnish was prepared.

(1-1)

In the coating curing furnace, the polyimide varnish was adjusted to a copper wire having a conductor diameter of 1 mm between 2 to 6 µm per coating thickness, the maximum temperature of the coating curing furnace was adjusted to 500 ° C, and the coating speed of the copper wire was 12 m. In the state adjusted to / min, a process of coating, drying, and curing a total of 7 times was repeated to prepare an electric wire including a polyimide coating having a coating thickness of 35 μm.

<Examples 2 to 13 and Comparative Examples 1 to 16>

In Example 1, the electric wires were prepared in the same manner as in Example 1, except that the viscosity of the monomer, additive, and polyimide varnish was changed as shown in Table 1 below.

<Comparative Example 9>

In Example 1, an electric wire was prepared in the same manner as in Example 1, except that instead of the compound of Formula 1-1 as an antioxidant, a compound of Formula A having a 5 wt% decomposition temperature of about 377 ° C was added.

(A)

<Comparative Example 10>

In Example 1, a wire was prepared in the same manner as in Example 1, except that instead of the compound of Formula 1-1 as an antioxidant, a compound of Formula B having a 5 wt% decomposition temperature of about 338 ° C. was added.

(B)

	ODA (mol%)	MDA (mol%)	PMDA (mol%)	BPDA (mol%)	Antioxidant		Coupling agent (parts by weight)	Silicone additives (parts by weight)	Low temperature curing agent (parts by weight)	Viscosity (cP)
					Kinds	Content (parts by weight)
Example 1	100	-	100	-	Formula 1-1	0.5	0.01	0.01	0.5	3,100
Example 2	100	-	100	-	Formula 1-1	0.5	0.01	0.01	2	3,100
Example 3	100	-	100	-	Formula 1-1	0.5	0.05	0.01	0.5	3,100
Example 4	100	-	100	-	Formula 1-1	0.5	0.01	0.05	0.5	3,100
Example 5	100	-	100	-	Formula 1-1	2	0.01	0.01	0.5	3,100
Example 6	100	-	100	-	Formula 1-1	0.1	0.01	0.01	0.5	3,100
Example 7	100	-	100	-	Formula 1-1	0.5	0.01	0.01	0.1	3,100
Example 8	50	50	100	-	Formula 1-1	0.5	0.01	0.01	0.5	5,500
Example 9	50	50	100	-	Formula 1-1	0.5	0.05	0.05	0.5	5,500
Example 10	100	-	-	100	Formula 1-1	0.5	0.01	0.01	0.5	3,780
Example 11	100	-	-	100	Formula 1-1	0.5	0.05	0.05	0.5	3,780
Example 12	50	50	-	100	Formula 1-1	0.5	0.01	0.01	0.5	4,200
Example 13	50	50	-	100	Formula 1-1	0.5	0.05	0.05	0.5	4,200
Comparative Example 1	100	-	100	-	Formula 1-1	0.5	-	-	-	3,100
Comparative Example 2	100	-	100	-	Formula 1-1	0.5	0.01	0.01	-	3,100
Comparative Example 3	100	-	100	-	Formula 1-1	0.5	-	0.01	0.5	3,100
Comparative Example 4	100	-	100	-	Formula 1-1	0.5	0.01	-	0.5	3,100
Comparative Example 5	100	-	100	-	Formula 1-1	0.5	0.01	0.01	2.5	3,100
Comparative Example 6	100	-	100	-	Formula 1-1	0.5	0.06	0.01	0.5	3,100
Comparative Example 7	100	-	100	-	Formula 1-1	0.5	0.01	0.06	0.5	3,100
Comparative Example 8	100	-	100	-	Formula 1-1	0.5	0.06	0.06	0.5	3,100
Comparative Example 9	100	-	100	-	Formula A	0.5	0.01	0.01	0.5	3,100
Comparative Example 10	100	-	100	-	Formula B	0.5	0.01	0.01	0.5	3,100
Comparative Example 11	50	50	100	-	Formula 1-1	0.5	-	0.01	0.5	5,500
Comparative Example 12	50	50	100	-	Formula 1-1	0.5	0.01	-	0.5	5,500
Comparative Example 13	50	50	100	-	Formula 1-1	0.5	0.01	0.01	-	5,500
Comparative Example 14	100	-	-	100	Formula 1-1	0.5	0.06	0.01	0.5	3,780
Comparative Example 15	100	-	-	100	Formula 1-1	0.5	0.01	0.06	0.5	3,780
Comparative Example 16	100	-	-	100	Formula 1-1	0.5	0.01	0.01	2.5	3,780

<Experimental Example 1: Evaluation of appearance defects>

The appearances of the polyimide coatings of the wires prepared in Examples 1 to 13 and Comparative Examples 1 to 16 were visually observed to determine whether they were defective and the results are shown in Table 2 below.

For example, when it is a coating of a good product, it is represented by 'O', and when an appearance defect such as pinhole or polyimide resin is carbonized, it is represented by 'X'.

<Experimental Example 2: Heat-resistant shock evaluation>

Heat resistance shock was evaluated for the polyimide coatings of the electric wires produced in Examples 1 to 13 and Comparative Examples 1 to 16. Heat shock is an indicator of whether a wire can withstand temperature exposure in an extended state or in a state where it is wound or bent around the mandrel.

Specifically, in order to evaluate the heat shock, the polyimide coatings of the wires prepared in Examples 1 to 13 and Comparative Examples 1 to 16 were heated at a temperature of 200 ° C. for 30 minutes, and then taken out of the oven, the specimen was cooled to room temperature, and then 20 % The number of cracks in the polyimide coating upon elongation was determined and the results are shown in Table 2 below.

	Appearance evaluation	Number of cracks at 20% elongation (ea)
Example 1	O	0
Example 2	O	0
Example 3	O	0
Example 4	O	0
Example 5	O	0
Example 6	O	0
Example 7	O	0
Example 8	O	0
Example 9	O	0
Example 10	O	0
Example 11	O	0
Example 12	O	0
Example 13	O	0
Comparative Example 1	X	15
Comparative Example 2	X	2
Comparative Example 3	X	3
Comparative Example 4	X	3
Comparative Example 5	O	0
Comparative Example 6	X	8
Comparative Example 7	X	7
Comparative Example 8	X	12
Comparative Example 9	O	0
Comparative Example 10	O	0
Comparative Example 11	O	One
Comparative Example 12	X	4
Comparative Example 13	X	2
Comparative Example 14	O	0
Comparative Example 15	X	6
Comparative Example 16	O	0

From the results of Table 2, in the case of the comparative example using a silicone-based additive, an alkoxy silane coupling agent, or a low temperature curing agent so as to fall outside the scope of the present invention, the coating of the polyimide coating may not be uniform, or partially carbonized, and heat shock Vulnerable to.

<Experimental Example 3: Property evaluation>

The physical properties of the polyimide coating of the wires prepared in Examples 1 to 13 and Comparative Examples 1 to 16 were measured using the following method, and the results are shown in Table 3 below.

(1) tanδ value

The tanδ value of the polyimide coating was measured using a TSE300 Tan Delta Tester from DSE.

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

(2) degree of softening

The degree of softening represents the decomposition temperature of an insulator, and is determined by measuring the temperature at which a short circuit occurs between two wires that cross each other at right angles when a specified load is applied to the intersection.

Specifically, the wires are stacked so as to cross at right angles, placed on a flat plate, and in the state where 1000 g of load is applied to the overlapped portions, an AC voltage of 100 V is applied and the temperature is shorted by raising the temperature at a rate of about 2 ° C / min. Was measured.

(3) Dielectric breakdown voltage (BDV)

The specimens 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 and the pressure vessel is heated for 72 hours, then the pressure vessel is cooled, the specimen is transferred to a 150 ° C. oven and held for 10 minutes and cooled to room temperature. BDV was measured by connecting both ends of the wire and increasing the AC voltage at the nominal frequency of the test voltage (60 Hz) between the wire conductors from 0 to a constant speed.

(4) Pinhole test

A pinhole test was performed to confirm whether there was a 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 a sodium chloride electrolyte containing phenolphthalein alcohol while connected to an electric circuit having a direct current test voltage, and then taken out to check the number of pinholes visually.

<Experimental Example 4: Pull test>

For the polyimide coatings of the wires prepared in Examples 1 to 14 and Comparative Examples 1 to 14, a pull test was conducted to confirm the adhesion between the conductor and the coating, and the results are shown in Table 3 below.

Specifically, a straight wire specimen having a free measuring length of 200-250 mm is quickly stretched to the breaking point or the elongation (20%) given in the standard. After stretching, inspect the specimen for the loss of adhesion or cracking at the specified magnification (1 to 6 times). The 2 mm length of the broken wire end should be neglected.

Three specimens are tested. Record any cracks and / or loss of adhesion on the wires.

	tanδ (℃)	Softening resistance (℃)	BDV (kV)	Pinhole count (ea)	Number of pull hook racks (ea)
Example 1	320	543	10.3	0	0
Example 2	315	563	10.1	0	0
Example 3	325	555	10.2	0	0
Example 4	335	557	10.5	0	0
Example 5	315	550	9.8	0	0
Example 6	310	535	9.7	0	0
Example 7	300	530	9.8	0	0
Example 8	305	522	9.5	One	0
Example 9	310	530	9.6	One	0
Example 10	295	520	9.3	0	0
Example 11	300	528	9.5	2	0
Example 12	285	505	8.8	0	0
Example 13	290	515	8.9	One	0
Comparative Example 1	250	474	6.3	12	15
Comparative Example 2	260	490	7.5	4	3
Comparative Example 3	265	495	7.8	10	8
Comparative Example 4	265	480	7.9	11	7
Comparative Example 5	260	475	7.5	2	2
Comparative Example 6	285	483	7.4	5	11
Comparative Example 7	285	490	7.5	8	4
Comparative Example 8	250	474	6.5	9	10
Comparative Example 9	290	495	9.2	0	0
Comparative Example 10	280	485	8.8	0	0
Comparative Example 11	255	480	7.8	5	0
Comparative Example 12	250	498	7.7	5	0
Comparative Example 13	245	475	7.0	4	4
Comparative Example 14	265	465	7.9	6	3
Comparative Example 15	265	470	7.8	5	0
Comparative Example 16	265	495	7.5	0	2

Referring to Table 3, the polyimide coatings of Examples 1 to 13 prepared from a polyimide varnish comprising a silicone-based additive and an alkoxy silane coupling agent, a low-temperature curing agent, and an antioxidant according to the present invention have tanδ of 270 ° C. or higher and internal combustion It can be seen that the degree of chemical conversion is excellent at heat resistance of 500 ° C or higher, the insulation breakdown voltage is 8 kV / mm or higher, and the adhesion is excellent between the conductor and the coating through a pull test.

On the other hand, in the case of Comparative Examples 1 to 16, which differ from the examples at the highest temperature of the silicone-based additive, alkoxy silane coupling agent, low temperature curing agent, antioxidant and solids content, viscosity, and curing temperature, tanδ compared to the example, It can be seen that at least one of the softening resistance and the breakdown voltage was decreased, and the number of pinholes according to the pinhole test, that is, a relatively large number of defects in the insulator was present. In addition, in some comparative examples, cracks were observed on the outer surface of the polyimide coating in the pulling test, and it can be confirmed that the adhesion between the conductor and the coating was lowered.

Although described above with reference to the embodiments of the present invention, those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above.

In the polyimide varnish according to the present invention, the alkoxy silane coupling agent and the silicone-based additive can improve the production yield by improving the adhesion between the polyimide coating and the conductor.

In addition, the low temperature curing agent included in the polyimide varnish achieves a high imidation rate even at a relatively low curing temperature and a small number of coatings or a low coating speed in the production process of the polyimide coating, such as heat resistance, insulation, flexibility, etc. At the same time as improving physical properties, it is possible to increase productivity and process efficiency.

The polyimide coating has the advantage of satisfying the heat resistance, insulation and flexibility required for the electronic device, and has an advantage of excellent adhesion between the polyimide coating and the conductor.

Claims (22)

1. As a polyimide varnish for conductor coating,

   A polyamic acid solution prepared by polymerizing one or more dianhydride monomers and one or more diamine monomers in an organic solvent;

   Silicone-based additives;

   Alkoxy silane coupling agents; And

   Contains a low temperature curing agent,

   The polyimide varnish having a softening resistance of 500 ° C or higher of the coating made from the polyimide varnish.
2. According to claim 1,

   A polyimide varnish comprising 0.01 to 0.05 parts by weight of a silicone-based additive with respect to 100 parts by weight of the solid content of the polyimide varnish.
3. According to claim 1,

   The silicone-based additives include dimethylpolysiloxane, polyether modified polydimethysiloxane polymethylalkylsiloxane, and hydroxyl group (-OH) and carbon-carbon double bond structure (C = C). A polyimide varnish comprising at least one member selected from the group consisting of silicon-based compounds.
4. According to claim 1,

   A polyimide varnish comprising 0.01 to 0.05 parts by weight of an alkoxy silane coupling agent with respect to 100 parts by weight of the solid content of the polyimide varnish.
5. According to claim 1,

   The alkoxy silane coupling agent is 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl methyl dimethoxysilane, 3-aminopropyl methyl diethoxysilane, 3- (2-aminoethyl) A polyimide varnish comprising at least one member selected from the group consisting of aminopropyl trimethoxysilane, 3-phenylaminopropyl trimethoxysilane, 2-aminophenyl trimethoxysilane, and 3-aminophenyl trimethoxysilane. .
6. According to claim 1,

   A polyimide varnish comprising 0.1 to 2 parts by weight of a low temperature curing agent relative to 100 parts by weight of the solid content of the polyimide varnish.
7. According to claim 1,

   The low temperature curing agent comprises at least one selected from the group consisting of betapicoline, isoquinoline, triethylenediamine and pyridine, polyimide varnish.
8. The method of claim 7,

   The low temperature curing agent comprises at least one selected from the group consisting of betapicoline, isoquinoline and pyridine, and triethylenediamine, polyimide varnish.
9. According to claim 1,

   The dianhydride monomer is pyromellitic dianhydride (PMDA) and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA, biphenyl-tetracarboxylic dianhydrid) from the group consisting of A polyimide varnish comprising one or more selected dianhydride monomers.
10. According to claim 1,

    The diamine monomer is a polyimide comprising at least one diamine monomer selected from the group consisting of 4,4'-diaminodiphenyl ether (or oxidianiline, ODA) and 4,4'-methylenedianiline (MDA). Varnish.
11. According to claim 1,

    The polyimide varnish, the polyimide varnish further comprises an antioxidant.
12. The method of claim 11,

    The antioxidant is 5% by weight decomposition temperature of 380 ℃ or more, polyimide varnish.
13. The method of claim 11,

    A polyimide varnish comprising 0.1 to 2 parts by weight of an antioxidant with respect to 100 parts by weight of the solid content of the polyimide varnish.
14. A method for producing the polyimide varnish according to claim 1,

    (a) polymerizing one or more dianhydride monomers and one or more diamine monomers in an organic solvent to prepare a polyamic acid solution; And

    (b) a method of preparing a polyimide varnish comprising a process of mixing a silicone-based additive, an alkoxy silane coupling agent, and a low temperature curing agent in the polyamic acid solution.
15. The method of claim 14,

    The process (a) is carried out at 30 to 80 ℃,

    The polyamic acid solution has a viscosity at 23 ° C in the range of 500 to 9,000 cP,

    The process (b) is carried out at 40 to 90 ℃, polyimide varnish production method.
16. (1) The process of coating the polyimide varnish according to claim 1 on the conductor surface; And

    (2) imidizing the polyimide varnish coated on the conductor surface to produce a polyimide coating,

    The above processes (1) and (2) are continuously repeated 4 to 20 times,

    The polyimide coating has a softening resistance of 500 ° C or higher, and a method for producing the polyimide coating.
17. The method of claim 16,

    The thickness of the polyimide varnish coated per repetition of the above steps (1) and (2) is 2 to 6 μm,

    The process (2) is carried out at 300 to 750 ℃,

    The conductor has a coating speed of 2 to 30 m / min, a method for producing a polyimide coating.
18. The method of claim 16,

    The conductor is a wire having a diameter of 0.1 to 5 mm, a method for producing a polyimide coating.
19. A polyimide coating prepared by the method according to claim 16.
20. The method of claim 19,

    The thickness of the polyimide coating ranges from 16 to 50 μm,

    tanδ is 270 ° C or higher,

    A polyimide coating having an insulation breakdown voltage (BDV) of 8 kV / mm or more.
21. A wire comprising a polyimide coating prepared by coating and imidizing the polyimide varnish of claim 1 on the surface of the wire.
22. An electronic device comprising the electric wire according to claim 21.