KR102164463B1 - Polyimide Film Having Low Permittivity and Low Hygroscopicity And Manufacturing Method thereof - Google Patents

Abstract

The present invention provides a method of preparing a polyimide film, comprising: (a) polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent to prepare a first polyamic acid; (b) polymerizing a dianhydride monomer and a diamine monomer in a second organic solvent to prepare a second polyamic acid, wherein at least one of the dianhydride monomer and diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine monomer ; (c) preparing a third polyamic acid by copolymerizing the first polyamic acid and the second polyamic acid in a third organic solvent; (d) preparing a precursor composition comprising a third polyamic acid; And (e) after forming a film on the precursor composition on a support, it provides a method for producing a polyimide film comprising the process of imidization.

Description

Polyimide Film Having Low Permittivity and Low Hygroscopicity And Manufacturing Method thereof

The present invention relates to a polyimide film having a low dielectric constant and low hygroscopicity, and a method of manufacturing the same.

In recent years, the introduction of advanced information transmission technology to network these electronic devices along with the high performance and high functionality of computers and communication devices is rapidly progressing, and as part of this, the amount of information transmitted to such electronic devices or communication devices constituting the network In accordance with the increase of the signal, high-frequency signals are in progress for high-speed processing and transmission technology.

Conventionally, high-frequency signals of 1 MHz or higher have been mainly used for limited wireless communication purposes such as aircraft or satellite communication, but recently they are also used in electronic devices such as mobile phones and wireless LANs, and due to the demand for faster operation speed and communication speed, more than 10 GHz High-speed transmission electronic devices capable of high-speed communication with high-frequency signals are being actively developed.

In order to realize such high-frequency, high-speed communication, it is required to overcome the problems of signal delay and transmission loss that occur in components of electronic equipment (eg, high-speed transmission circuit boards) mounted in communication equipment. Specifically, the signal delay (RC delay) is expressed as the product of the capacitance (C) and the wiring resistance (R) between metal wires, which increases in proportion to the square root of the dielectric constant of the insulator. According to the trend of miniaturization and high integration, the entire signal transmission is further delayed due to propagation delay or crosstalk noise. In addition, transmission loss is divided into conductor loss and dielectric loss, which are proportional to dielectric constant and dielectric loss tangent of an insulator, and tend to increase as the frequency increases.

That is, the high-frequency characteristics of the electronic device for high-speed transmission are particularly closely related to the dielectric characteristics of the insulating layer. Therefore, for high-frequency, high-speed communication, it is necessary to use an insulating material having a very low dielectric constant. Conventionally, a substrate made of fluororesin (PTFE), which is known to have the best high-frequency properties among polymer materials, was standardized in MIL (Military Specifications and Standards) in 1975 and used for aviation, space, and military applications. However, since PTFE is a thermoplastic resin having a glass transition temperature near room temperature, it lacks dimensional stability against heat, has poor mechanical strength and thermal conductivity, requires a special plating pretreatment process, and has moldability (350℃). The above high temperature) and workability were also problematic.

Therefore, in recent years, the possibility of utilizing polyimide resins for high-speed transmission electronic devices has been studied.

In general, the polyimide resin refers to a highly heat-resistant resin prepared by solution polymerization of an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to prepare a polyamic acid derivative, followed by ring closure dehydration at a high temperature to imidize it. It is based on a rigid aromatic backbone and an imide ring with excellent chemical stability, so it is a polymer material with the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance and weather resistance among organic materials. It is in the spotlight as an insulating material for electronic devices for high-speed communication because it is relatively stable in the area and has a high dielectric breakdown voltage.

However, since polyimide itself has a high moisture absorption rate due to the characteristics of the material, there are certain limitations to the expression of low dielectric constant despite the excellent physical properties. To overcome this, in recent years, high performance of polyimide, especially high frequency Research on low dielectric constant and low dielectric loss tangent as corresponding electrical characteristics is being actively conducted.

For example, as an attempt to lower the dielectric constant of a polyimide resin, an aromatic obtained from an aromatic tetracarboxylic acid component and an aromatic diamine component mainly composed of biphenyltetracarboxylic acids in the presence of a surfactant compound having a fluorine atom in the fluorine resin powder. A fluororesin-containing polyimide composition characterized in that polyimide is uniformly dissolved in an organic polar solvent capable of dissolving the aromatic polyimide and a method for producing the same have been proposed, but polyimide containing a fluorine-containing surfactant, etc. Due to the effect of the fluorine-based resin, the dielectric constant and the dielectric loss tangent can be reduced to some extent, but surfactants and dispersants containing fluorine generally increase the dielectric constant and dielectric loss tangent, and it is difficult to sufficiently improve the electrical properties. There is a limit.

On the other hand, a technology for including both aromatic polyimide and aliphatic polyimide in the molecule of the polyimide film has been proposed for low dielectric constant, but conventional polyimide manufacturing methods are used to distinguish the characteristics of aromatic polyimide and aliphatic polyimide. Physical properties due to their structural characteristics, such as excellent mechanical and thermal properties based on an aromatic main chain and low hygroscopicity based on an aliphatic main chain, have been limited.

In addition, although the aromatic monomer constituting the aromatic polyimide and the aliphatic monomer constituting the aliphatic polyimide differ from each other in reaction characteristics with respect to a solvent, conventionally, they are not used separately, causing a problem in the process.

Therefore, it is necessary to develop a method for producing a polyimide film capable of exhibiting a low dielectric constant in a high frequency band (e.g., 10 GHz or more) while maintaining the excellent mechanical and thermal properties of polyimide, and a polyimide film manufactured therefrom. to be.

It is an object of the present invention to provide a polyimide film and a method for producing the same, while maintaining excellent mechanical and thermal properties of the polyimide while exhibiting low dielectric constant and low hygroscopicity.

According to an aspect of the present invention, a method for preparing a polyimide film includes a process of polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent to prepare a first polyamic acid, and a dianhydride monomer and a diamine monomer as a second method. A second polyamic acid is prepared by polymerization in an organic solvent, and at least one of the dianhydride monomer and the diamine monomer is prepared by dividing the process of being an aliphatic dianhydride monomer or an aliphatic diamine monomer.

In this aspect, the manufacturing method can be useful for suppressing the dielectric constant and hygroscopicity of the polyimide film, and the polyimide film produced therefrom is a polyimide film capable of simultaneously realizing excellent mechanical and thermal properties and low moisture absorption properties. It can provide a manufacturing method of.

As a result, according to one aspect of the present invention, the prior problems can be solved.

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

The present invention is a method for producing a polyimide film,

(a) polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent to prepare a first polyamic acid;

(b) polymerizing a dianhydride monomer and a diamine monomer in a second organic solvent to prepare a second polyamic acid, wherein at least one of the dianhydride monomer and diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine monomer ;

(c) preparing a third polyamic acid by copolymerizing the first polyamic acid and the second polyamic acid in a third organic solvent;

(d) preparing a precursor composition comprising a third polyamic acid; And

(e) It provides a method for producing a polyimide film, including the process of imidizing after forming the precursor composition on a support.

The present invention is also a polyimide film comprising a polyimide copolymer prepared by imidizing a polyamic acid copolymer,

The polyimide copolymer includes a first unit block and a second unit block,

The first unit block is an imidized structure of a first polyamic acid prepared by polymerization of an aromatic dianhydride monomer and an aromatic diamine monomer,

The second unit block is an imidized structure of a second polyamic acid prepared by polymerizing a dianhydride monomer and a diamine monomer, and at least one of the dianhydride monomer and diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine It provides a monomer, a polyimide film.

The present invention can also provide an electronic device for high-speed transmission including the polyimide film.

Hereinafter, detailed contents for implementation thereof will be described in the present specification.

Prior to this, terms or words used in the specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventors appropriately explain the concept of terms in order to explain their own invention in the best way. Based on the principle that it can be defined, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

Therefore, the configuration of the embodiments described in the present specification 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 application It should be understood that examples may exist.

In the present specification, expressions in the singular include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as "comprise", "include" or "have" are intended to designate the presence of implemented features, numbers, steps, components, or a combination thereof, and one or more other features or It is to be understood that the possibility of the presence or addition of numbers, steps, elements, or combinations thereof is not preliminarily excluded.

In the present specification, "dianhydride (dianhydride)" is intended to include its precursor or derivative, which may not be technically dianhydride, but nevertheless react with diamine to form polyamic acid. And this polyamic acid can be converted back to polyimide.

In the present specification, "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but nevertheless will react with dianhydride to form polyamic acid, which polyamic acid is again polyamic acid. Can be converted to mid.

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

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

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

<Production method of polyimide film>

The method for preparing a polyimide film according to the present invention includes: (a) polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent to prepare a first polyamic acid;

(b) polymerizing a dianhydride monomer and a diamine monomer in a second organic solvent to prepare a second polyamic acid, wherein at least one of the dianhydride monomer and diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine monomer ;

(c) preparing a third polyamic acid by copolymerizing the first polyamic acid and the second polyamic acid in a third organic solvent;

(d) preparing a precursor composition comprising a third polyamic acid; And

(e) After forming the precursor composition onto a support, it is characterized in that it comprises a process of imidization.

In one specific example, the aromatic dianhydride monomer is pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA), and benzophenonetetra. It may contain at least any one selected from the group consisting of carboxylic dianhydride (BTDA), and these may be used singly or in combination of two or more as desired.

In addition, the aromatic diamine monomer is 4-phenylenediamine (PPD), 4,4'-oxydianiline (ODA), 3,4'-oxydianiline, 4,4'-methylenedianiline (MDA), And 1,3-bis (4-aminophenoxy) benzene (TPE-R) may include at least any one selected from the group consisting of, these may be used alone or in combination of two or more as desired. .

The polyimide chain formed by imidization of the first polyamic acid prepared by polymerizing the aromatic dianhydride monomer and the aromatic diamine monomer may include a structure derived from the aromatic monomer.

This will be described in more detail later, but due to such an aromatic unit structure, the polyimide film according to the present invention can exhibit excellent mechanical and thermal properties of the polyimide as it is.

In another specific example, the aliphatic dianhydride monomer is 1,2,4,5-cyclohexanetetracarboxylicdianhydride (HPMDA), 2,2-bis[4-(3,4dicarboxyphenoxy) Phenyl]propanedianhydride (BPADA), bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylicdianhydride (BOCA), and cyclobutane-1,2 , 3,4-tetracarboxylic dianhydride (CBDA) may contain at least any one selected from the group consisting of.

In addition, the aliphatic diamine monomer is, for example, cyclohexanediamine (CHD), 1,4-cyclohexanebis (methylamine), 2,2-bis[(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[4-(4-aminophenoxyphenyl)]hexafluoropropane (HFBAPP), 4,4'-methylenebiscyclohexylamine (MCA), 4,4'-methylenebis(2-methyl Cyclohexylamine) (MMCA), 1,3-diaminoadamantane (DAA), 3,3'-diamino-1,1'-diadamantane (DADA), isophorone diamine, 4, 4'-diaminodicyclohexyl methane (4,4'-Diaminodicyclohexyl methane), 3,3'-dimethyl-4,4'-diaminodicyclohexyl methane (3,3'-Dimethyl-4,4' -Diaminodicyclohexyl methane) and 3,3',5,5' tetramethyl -4,4'-diaminodicyclohexyl methane (3,3',5,5'-Tetramethyl-4,4'- Diaminodicyclohexyl methane) It may include at least any one selected from the group consisting of, and in detail, may be cyclohexanediamine (CHDA).

More specifically, the cyclohexanediamine (CHDA) is, for example, 1,2-cyclohexanediamine (1,2-Cyclohexanediamine), 1,3-cyclohexanediamine (1,3-Cyclohexanediamine), 1,4 -Cyclohexanediamine (1,4-Cyclohexanediamine), N,N'-dimethyl-1,2-cyclohexanediamine (N,N'-Dimethyl-1,2-Cyclohexanediamine), 4-methyl-1,3-cyclo Hexanediamine (4-Methyl-1,3-Cyclohexanediamine), (1R,2R)-N,N,N',N'-tetramethyl-1,2-cyclohexanediamine ((1R,2R)-N,N ,N',N'-Tetramethyl-1,2-Cyclohexanediamine) and N,N'-dipropyl cyclohexanediamine (N,N'-Dipropyl Cyclohexanediamine) may be at least one selected from the group consisting of.

The polyimide chain formed by imidization of the second polyamic acid prepared by polymerizing the aliphatic dianhydride monomer or the aliphatic diamine monomer may include a structure derived from the aliphatic monomer.

The structure derived from the aliphatic monomer may be appropriately selected to have non-polarity, and as non-limiting examples of the structure derived from the aliphatic monomer -CH ₃ , -CF ₃ , Chain aliphatic hydrocarbon group and cyclic aliphatic hydrocarbon group And the like.

This will be described in more detail later, but since the structure derived from such an aliphatic monomer exhibits non-polarity, the polyimide film according to the present invention can exhibit a low moisture absorption rate. In another aspect, since the structure derived from the aliphatic monomer is included in the second polyamic acid, the ratio of the amic acid group causing the increase in hygroscopicity can be relatively reduced, so that the moisture absorption rate of the polyimide film prepared therefrom can be lowered positively. Can work.

However, as described above, it may be effective to increase the content of the structure derived from the aliphatic dianhydride monomer or the aliphatic diamine monomer in order to lower the moisture absorption rate, but as the structure derived from the aliphatic monomer increases, the polyimide film prepared therefrom There is a problem in that the mechanical properties of are deteriorated, and it is difficult to achieve a desired level of glass transition temperature.

Moreover, as in the conventional polyamic acid production method, for example, when producing a polyamic acid by simultaneously adding an aromatic dianhydride monomer, an aromatic diamine monomer, an aliphatic dianhydride monomer, and an aliphatic diamine monomer, in the polyimide chain produced therefrom Since a structure derived from an aromatic monomer capable of exhibiting excellent mechanical and thermal properties and a structure derived from an aliphatic monomer capable of exhibiting a low moisture absorption rate are not generated, there may be a problem in that a polyimide film in which these physical properties are simultaneously expressed cannot be produced.

On the other hand, in the case of the production method according to the present invention, in order to effectively express the excellent properties of each monomer, the process of polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent to prepare a first polyamic acid and By polymerizing a dianhydride monomer and a diamine monomer in a second organic solvent to prepare a second polyamic acid, and at least one of the dianhydride monomer and diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine monomer. , The polyimide film prepared therefrom can simultaneously implement excellent mechanical and thermal properties and low moisture absorption properties.

In one specific example, the weight average molecular weight of the first polyamic acid and the second polyamic acid may be 6,000 to 60,000 g/mole, in detail 7,000 to 20,000 g/mole, more specifically 10,000 to 15,000 g/ mole, more specifically 12,000 to 15,000 g/mole.

If the weight average molecular weight of the first polyamic acid and the second polyamic acid exceeds the above range, the disadvantages of the structure derived from the aromatic monomer in the polyimide chain prepared therefrom, such as high dielectric constant and moisture absorption rate, may be highlighted. , Since the disadvantages of the structure derived from the aliphatic monomer, for example, the mechanical properties and the thermal properties are deteriorated may be emphasized, it is not preferable.

Conversely, if the weight average molecular weight of the first polyamic acid and the second polyamic acid is less than the above range, the aromatic monomer of the polyimide chain prepared therefrom is similar to the conventional method of preparing a polyamic acid by simultaneously adding the monomers. The excellent mechanical and thermal properties of the derived structure and the low dielectric constant and low moisture absorption rate of the aliphatic monomer-derived structure are not simultaneously expressed, which is not preferable.

That is, in the present invention, the excellent characteristics of each of the structure derived from the aromatic monomer and the structure derived from the aliphatic monomer are highlighted, and so that their disadvantages do not appear, the first polyamic acid and the second polyamic acid are polymerized to have a constant molecular weight. , It is characterized in that the first polyamic acid and the second polyamic acid are polymerized again to prepare a third polyamic acid and imidized to prepare a polyimide film.

In this case, the weight average molecular weight of the third polyamic acid may be 100,000 g/mole or more. More specifically, the weight average molecular weight of the third polyamic acid may be 100,000 to 200,000 g/mole.

When the weight average molecular weight of the third polyamic acid exceeds the above range, it is inevitable to increase the viscosity of the precursor composition containing the third polyimide film. This is when the precursor composition is moved through a pipe during the manufacturing process of the polyimide film. Since a higher pressure must be applied due to friction with the pipe, the process cost may increase and the handling may decrease. In addition, the higher the viscosity, the more time and cost may be required for the mixing process.

Moreover, the film forming process itself may be impossible due to an excessively high viscosity, and even if the film forming process is possible, the physical properties of the polyimide film produced therefrom may be deteriorated, which is not preferable.

On the contrary, if the weight average molecular weight of the third polyamic acid is less than the above range, the effect of the present invention to highlight the excellent physical properties of each of the first polyamic acid and the second polyamic acid cannot be exhibited.

Meanwhile, a third polyamic acid may be prepared by copolymerizing the first polyamic acid and the second polyamic acid in a molar ratio of 8:2 to 6:4, and in detail, 7:3 to 6:4.

At this time, when the molar ratio of the first polyamic acid and the second polyamic acid exceeds the above range and the first polyamic acid is included in an excessive amount, the content of the structure derived from the aliphatic monomer included in the polyimide chain is relatively very small, It may be difficult to express the dielectric constant and low moisture absorption characteristics.

Conversely, when the molar ratio of the first polyamic acid and the second polyamic acid is less than the above range and the second polyamic acid is included in an excessive amount, the content of the structure derived from the aliphatic monomer contained in the polyimide chain prepared therefrom is too high. , Mechanical properties and thermal properties of the polyimide film may be deteriorated.

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

(1) a method of polymerizing by putting the entire amount of the diamine monomer into a solvent, and then adding the dianhydride monomer so that it becomes substantially equimolar with the diamine monomer;

(2) a method of polymerizing by putting the entire amount of the dianhydride monomer into a solvent, and then adding the diamine monomer so as to be substantially equimolar with the dianhydride monomer;

(3) After adding some components of the diamine monomer in the solvent, mixing some components of the dianhydride monomer with respect to the reaction component in a ratio of about 95 to 105 mol%, the remaining diamine monomer components are added, followed by the remaining A method of polymerization by adding a dianhydride monomer component to make the diamine monomer and the dianhydride monomer substantially equimolar;

(4) After putting the dianhydride monomer in the solvent, some components of the diamine compound are mixed in a ratio of 95 to 105 mol% with respect to the reaction component, and then another dianhydride monomer component is added, followed by the remaining diamine monomer component. A method of polymerization by adding to make the diamine monomer and the dianhydride monomer substantially equimolar;

(5) In a solvent, some diamine monomer components and some dianhydride monomer components are reacted so that any one is in excess to form a first composition, and some diamine monomer components and some dianhydride monomer components are selected in another solvent. A method of mixing the first and second compositions and completing polymerization after forming a second composition by reacting so that one is in excess. In this case, when the diamine monomer component is excessive when forming the first composition, the second When the dianhydride monomer component is excessive in the composition, and the dianhydride monomer component is excessive in the first composition, the diamine monomer component is excessive in the second composition, and the first and second compositions are mixed to prevent these reactions. A method of polymerization by making all the diamine monomer components used and the dianhydride monomer components substantially equimolar; And the like.

The polymerization method may be applied to polymerization of a first polyamic acid, polymerization of a second polyamic acid, and polymerization of a third polyamic acid, respectively.

It goes without saying that the polymerization method is not limited to the above examples, and any known method may be used.

Meanwhile, the first to third solvents used in the present invention are not particularly limited as long as they are organic solvents in which polyamic acid can be dissolved, but may be an aprotic polar solvent as an example.

As a non-limiting example of the aprotic polar solvent, amide solvents such as N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), p-chlorophenol, o-chloro Phenolic solvents such as phenol, N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL), and Diglyme, and these may be used alone or in combination of two or more.

In some cases, an auxiliary solvent such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, or water may be used to adjust the solubility of the polyamic acid.

In one example, the organic solvent that can be particularly preferably used for the first and third organic solvents may be amide-based solvents, N,N'-dimethylformamide and N,N'-dimethylacetamide.

In another example, the organic solvent that can be particularly preferably used for the second organic solvent may be N-methyl-pyrrolidone (NMP).

Meanwhile, a filler may be added to the "precursor composition manufacturing process" for the purpose of improving various properties of the film such as sliding property, thermal conductivity, conductivity, corona resistance, and loop hardness. The filler to be added is not particularly limited, but preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, and the like.

The particle diameter of the filler is not particularly limited, and can be determined according to the film properties to be modified and the type of filler to be added. In general, the average particle diameter is 0.05 to 20 µm, preferably 0.1 to 10 µm, more preferably 0.1 to 5 µm, and particularly preferably 0.1 to 3 µm.

If the particle diameter is less than this range, the modification effect is difficult to appear, and if it exceeds this range, the surface properties may be greatly impaired or the mechanical properties may be greatly reduced.

Further, the amount of the filler to be added is not particularly limited, and may be determined by the film properties to be modified, the filler particle size, or the like. In general, the amount of the filler added is 0.01 to 10 parts by weight, preferably 0.01 to 5 parts by weight, and more preferably 0.02 to 1 part by weight based on 100 parts by weight of the polyimide resin.

If the amount of the filler added is less than this range, the effect of modifying by the filler is difficult to appear, and if it exceeds this range, the mechanical properties of the film may be greatly impaired. The method of adding the filler is not particularly limited, and any known method may be used.

For a method of imidizing the precursor composition prepared as described above to prepare a polyimide film, a conventionally known method can be used.

Specific methods of such imidization include thermal imidation, chemical imidation, or a complex imidization method in which the thermal imidation and chemical imidation are used in combination, and the following non-limiting examples are given. It will be described in more detail through.

<Thermal imidization method>

The thermal imidation method is a method of inducing an imidation reaction with a heat source such as hot air or an infrared dryer, excluding a chemical catalyst,

Drying the precursor composition to form a gel film; And

Heat treatment of the gel film may include a process of obtaining a polyimide film.

Here, the gel film can be understood as a film intermediate having self-supporting properties in an intermediate step for conversion from polyamic acid to polyimide.

In the process of forming the gel film, the precursor composition is cast in a film form on a support such as a glass plate, an aluminum foil, an endless stainless belt, or a stainless drum, and then the precursor composition on the support is 50°C to 200°C, Specifically, it may be drying at a variable temperature in the range of 80 ℃ to 150 ℃.

Accordingly, a gel film may be formed by partial curing and/or drying of the precursor composition, and a gel film may be obtained by peeling the formed gel film from the support.

In some cases, a process of stretching the gel film may be performed in order to adjust the thickness and size of the polyimide film obtained in the subsequent heat treatment process and improve orientation, and the stretching may be performed in the machine transfer direction (MD) and the machine transfer direction. It may be performed in at least one of the transverse directions TD.

The gel film thus obtained is fixed to a tenter and then heat-treated at a variable temperature in the range of 50°C to 500°C, specifically 150°C to 500°C to remove water and residual solvent remaining in the gel film, and Almost all of the amic acid groups can be imidized to obtain the polyimide film of the present invention.

In some cases, the polyimide film obtained as described above may be further cured by heating and finishing at a temperature of 300° C. to 600° C. for 5 to 400 seconds to further cure the polyimide film, which may remain in the obtained polyimide film. It is also possible to do this under a predetermined tension in order to relieve the internal stress.

<Chemical imidization method>

The chemical imidization method is a method of promoting imidization of an amic acid group by adding a dehydrating agent and/or an imidizing agent to the precursor composition.

Here, the "dehydrating agent" means a substance that promotes a ring closure reaction through a dehydration action on polyamic acid, and non-limiting examples thereof include an aliphatic acid anhydride, an aromatic acid anhydride, N,N' -Dialkylcarbodiimide, halogenated lower aliphatic, halogenated lower patty acid anhydride, aryl phosphonic dihalides, and thionyl halides. Among these, aliphatic acid anhydride may be preferable from the viewpoint of availability and cost, and non-limiting examples thereof include acetic anhydride (AA), propion acid anhydride, and lactic acid anhydride. And the like, and these may be used alone or in combination of two or more.

In addition, the term "imidating agent" refers to a substance having an effect of promoting a ring closure reaction with respect to polyamic acid, and is an imine component such as an aliphatic tertiary amine, an aromatic tertiary amine, and a heterocyclic tertiary amine. I can. Among these, a heterocyclic tertiary amine may be preferable from the viewpoint of reactivity as a catalyst. Non-limiting examples of the heterocyclic tertiary amine include quinoline, isoquinoline, β-picoline (BP), pyridine, and the like, and these may be used alone or in combination of two or more.

The amount of the dehydrating agent added is preferably in the range of 0.5 to 5 moles, and particularly preferably in the range of 1.0 to 4 moles per 1 mole of the amic acid group in the polyamic acid. In addition, the amount of the imidizing agent added is preferably within the range of 0.05 to 2 moles, and particularly preferably within the range of 0.2 to 1 mole, per 1 mole of the amic acid group in the polyamic acid.

If the dehydrating agent and the imidizing agent are less than the above ranges, chemical imidization is insufficient, cracks may be formed in the polyimide film to be produced, and the mechanical strength of the film may be reduced. In addition, if the amount of these additions exceeds the above range, imidization may proceed excessively quickly, and in this case, it is difficult to cast into a film or the manufactured polyimide film may exhibit brittle characteristics, which is not preferable. not.

<Complex imidization method>

In connection with the above chemical imidization method, a composite imidization method in which a thermal imidization method is additionally performed can be used for the production of a polyimide film.

Specifically, the composite imidization method includes a chemical imidization process of adding a dehydrating agent and/or an imidizing agent to a precursor composition at a low temperature; And a thermal imidization process of drying the precursor composition to form a gel film and heat-treating the gel film.

When performing the chemical imidization process, the types and amounts of the dehydrating agent and the imidizing agent may be appropriately selected as described in the above chemical imidization method.

In the process of forming the gel film, a precursor composition containing a dehydrating agent and/or an imidizing agent is cast in a film form on a support such as a glass plate, an aluminum foil, an endless stainless belt, or a stainless drum, and then on the support. The precursor composition is dried at varying temperatures ranging from 50°C to 180°C, specifically 80°C to 180°C. In this process, a chemical converting agent and/or an imidizing agent may act as a catalyst to rapidly convert an amic acid group into an imide group.

In some cases, a process of stretching the gel film may be performed in order to adjust the thickness and size of the polyimide film obtained in the subsequent heat treatment process and improve orientation, and the stretching may be performed in the machine transfer direction (MD) and the machine transfer direction. It may be performed in at least one of the transverse directions TD.

The gel film thus obtained is fixed to a tenter and then heat-treated at a variable temperature ranging from 50°C to 700°C, specifically 150°C to 600°C to remove water, catalyst, residual solvent, etc. remaining in the gel film, By imidizing most of the remaining amic acid groups, the polyimide film of the present invention can be obtained. Even in such a heat treatment process, a dehydrating agent and/or an imidizing agent may act as a catalyst to rapidly convert an amic acid group into an imide group, thereby enabling a high imidation rate.

In some cases, the polyimide film obtained as described above may be heated and finished at a temperature of 400°C to 500°C for 5 to 400 seconds to further cure the polyimide film, and the inside which may remain in the obtained polyimide film It is also possible to do this under a certain tension to relieve the stress.

<Polyimide Film>

The polyimide film according to the present invention is a polyimide film comprising a polyimide copolymer prepared by imidizing a polyamic acid copolymer,

The polyimide copolymer includes a first unit block and a second unit block,

The first unit block is an imidized structure of a first polyamic acid prepared by polymerization of an aromatic dianhydride monomer and an aromatic diamine monomer,

The second unit block is an imidized structure of a second polyamic acid prepared by polymerizing a dianhydride monomer and a diamine monomer, and at least one of the dianhydride monomer and diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine It is characterized by being a monomer.

In one specific example, the weight average molecular weight of the first unit block and the second unit block may be 6,000 to 60,000 g/mole, in detail 7,000 to 20,000 g/mole, more specifically 10,000 to 15,000 g/mole. mole, more specifically 12,000 to 15,000 g/mole.

In general, the weight average molecular weight of the first unit block and the second unit block in a polyimide resin state has a value substantially very similar to the weight average molecular weight of the first polyamic acid and the second polyamic acid described above. Depending on the range of the weight average molecular weight, the above-described problem may occur.

In addition, the weight average molecular weight of the polyimide copolymer may be 100,000 g/mole or more, and the molar ratio of the first unit block and the second unit block may be 8:2 to 6:4, and more specifically, 7 : 3 to 6: may be 4.

The weight average molecular weight of the polyimide copolymer may have a value similar to the weight average molecular weight of the third polyamic acid described above, and the molar ratio of the first unit block and the second unit block is also the ratio of the first polyamic acid and the second polyamic acid. Since the molar ratio may have a value substantially very similar to the molar ratio, the above-described problem may occur depending on the range of their weight average molecular weight or molar ratio.

In one specific example, the first unit block and the second unit block may be represented by the following Chemical Formulas 1 and 2, respectively.

[Formula 1]

Here, n is an integer of 20 or more and 150 or less.

[Formula 2]

Here, m is an integer of 20 or more and 150 or less.

Meanwhile, the structure derived from the aliphatic dianhydride monomer or the aliphatic diamine monomer included in the second unit block may be 10 to 30% by weight based on the total weight of the polyimide copolymer.

When the content of the structure derived from the aliphatic dianhydride monomer or the aliphatic diamine monomer exceeds the above range, it is difficult to express excellent mechanical and thermal properties of the polyimide film, and if it is less than the above range, the desired dielectric constant and moisture absorption rate It is difficult to achieve, which is not desirable.

On the other hand, the polyimide film according to the present invention at 10 GHz (a) has a dielectric constant of 3.2 or less, (b) a moisture absorption of 1.5 wt% or less, and (c) a tensile strength of 4.2 GPa Above, (d) the glass transition temperature (Tg) may be 310 ℃ or higher.

In this regard, in the case of the polyimide film according to the present invention that satisfies both the conditions of (a) permittivity and (b) moisture absorption, it can be used as an insulating film used in electronic devices for high-speed transmission, and at least 10 GHz Even if it is used as an electrical signal transmission circuit that transmits signals at high frequency, signal delay and transmission loss can be minimized based on excellent insulation stability.

In addition, in the case of the polyimide film according to the present invention that satisfies the conditions of (c) tensile strength and (d) glass transition temperature above, it may exhibit excellent mechanical properties and thermal properties.

Hereinafter, the four conditions will be described in detail.

<Dielectric constant>

Permittivity is an important characteristic value representing the electrical characteristics of a dielectric (or insulator), that is, a non-conductor. Permittivity does not represent the electrical characteristics of DC current, but is directly related to the characteristics of AC current, especially AC electromagnetic waves. It is known.

In an insulator (for example, a polyimide film), the + and-moment components, which are usually scattered in random directions, are aligned according to the alternating current of the electromagnetic field applied from the outside. That is, the moment components change according to the change direction of the electromagnetic field, so that it is possible to propagate the electromagnetic wave inside while being a non-conductor.

The degree to which the moment inside the material reacts sensitively to such changes in the external electromagnetic field can be expressed as the dielectric constant, and the high dielectric constant means that the electric energy is well transferred, so an insulator such as a polyimide film has a dielectric constant. The lower the more preferable.

That is, while a typical polyimide film has a dielectric constant higher than a level that can maintain sufficient insulation for high frequency communication, the polyimide film according to the present invention, as an example, may have a dielectric constant of 3.2 or less at 10 GHz. And, preferably, it may be 3.0 or less, and its lower limit may be at least 2.2. It can be seen that the polyimide film exhibits an ideal dielectric constant as an insulator, considering that the engineering properties of the polyimide film are at the highest level.

On the other hand, even if all conductors are separated from each other, capacitive coupling by an electric field always exists between them, so even if the layers of the multilayer substrate are electrically separated from each other, it is an open circuit for direct current. In reality, it can be seen that a capacitor of a certain value is connected between them.

In this case, the capacitor has a property of lowering the impedance as the frequency of the current or voltage at both ends thereof increases, and the value can be expressed as follows.

-Impedance = 1/(2*π*f*C); Where f is the frequency and C=capacitance.

-C = e*S/d; Where e is the dielectric constant, S is the area of the conductor, and d is the distance.

In general, at a scale that can be seen and handled with bare hands, it is difficult for the capacitance value (farad) between the two conductors to deviate from the pico unit no matter how close they are, and the C between layers is similar to the general PCB. Because it is so small, insulation between layers can be maintained even if the circuit operates at a certain high frequency, but in the case of a high-speed transmission electronic device operating at a high frequency of 10 GHz or higher, for example, a GIGA unit frequency, as in the above equation. Insulation may be difficult to maintain because impedance is very low due to high frequency values. When selecting an insulator, use a material with a low dielectric constant, that is, a material with a low dielectric constant, to minimize electrostatic coupling and capacitance (i.e., impedance). shall.

Accordingly, the polyimide film according to the present invention exhibits a relatively low dielectric constant as described above by containing a structure derived from an aliphatic monomer in the polyimide chain derived from the second polyamic acid. Specifically, since the structure derived from the aliphatic monomer has a lower probability of forming a specific gravity, molecular density, polarity, and charge transfer complex compared to the structure derived from an aromatic monomer, the dielectric constant can be reduced.

Accordingly, the polyimide film of the present invention has the advantage of being easy to maintain insulation even in electronic devices for high-speed transmission that operate at a frequency of a giga (GIGA) unit, for example, a high frequency of 10 GHz or more.

<Moisture absorption rate>

The moisture absorption rate is a ratio showing the amount of moisture absorbed by the material. In general, it is known that the dielectric constant increases when the moisture absorption rate is high, and water has a dielectric constant of 100 or more when it is in a solid state, about 80 when it is in a liquid state, and 1.0059 when it is in a gaseous state.

Accordingly, water in the vapor state of the polyimide film does not substantially affect the dielectric constant of the polyimide film, but when water is absorbed in the polyimide film in a liquid state, the dielectric constant may increase dramatically. That is, even with only a small amount of moisture absorption, there is a concern that the dielectric constant of the polyimide film is rapidly changed and the dielectric constant is remarkably increased.

Therefore, it can be seen that the low moisture absorption rate is a physical property that is necessarily required for the polyimide film to be used as an insulating film.

The polyimide film according to the present invention exhibits non-polarity in the molecular structure -CH ₃ , -CF ₃ , It is predicted to be due to containing a polyimide chain including at least one of a chain aliphatic hydrocarbon group or a cyclic aliphatic hydrocarbon group.

<Tensile strength>

In the present invention, when the tensile strength is applied to the film, the resistance until the film breaks is referred to as the strength. The strength includes bending strength, torsional strength, tensile strength, etc., depending on the method of applying the load, and since these strengths have a certain relationship with tensile strength, they can be taken as a standard of film strength with tensile strength.

Tensile strength is expressed in units of GPa, and is the maximum load that has been endured in, and can be used as an index indicating the mechanical properties of the polyimide film.

<Glass transition temperature>

In the present invention, the glass transition temperature can be obtained from the storage modulus and loss modulus measured by a dynamic viscoelasticity measuring device (DMA), and in detail, the top peak of tan δ is a value obtained by dividing the calculated loss modulus by the storage modulus. Can be calculated as a glass transition degree.

The glass transition temperature is preferably high because it means the heat resistance of the polyimide film. However, in the polyimide film, it is difficult to achieve the highest level of glass transition ion and low dielectric constant. The reason for this is that the strong heat resistance of the polyimide film is due to the chemical stability of the imide group, but since the imide group is polar, it is relative to moisture absorption. It is predicted to be due to its weakness.

Specifically, the glass transition temperature of the polyimide film according to the present invention may be 220° C. or higher, specifically 230° C. or higher, and more specifically 310° C. or higher.

As described above, as the polyimide film according to the present invention satisfies all the above four conditions, it exhibits excellent mechanical and thermal properties and at the same time ensures insulation stability even at high frequencies, signal delay and transmission loss. Can be minimized.

The present invention also provides an electronic device for high-speed transmission comprising the polyimide film.

The electronic device for high-speed transmission may be an electronic device that transmits a signal at a high frequency of at least 2 GHz, specifically, a high frequency of at least 5 GHz, and more particularly, a high frequency of at least 10 GHz.

The electronic device may be, for example, a communication circuit for a portable terminal, a communication circuit for a computer, or a communication circuit for aerospace, but is not limited thereto.

The manufacturing method of the polyimide film according to the present invention is a process of preparing a first polyamic acid by polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent in order to effectively express the excellent properties of each monomer. By polymerizing a hydride monomer and a diamine monomer in a second organic solvent to prepare a second polyamic acid, at least one of the dianhydride monomer and the diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine monomer, The polyimide film produced therefrom can maintain excellent mechanical and thermal properties and at the same time realize low moisture absorption properties.

In addition, the polyimide film according to the present invention has a dielectric constant of 3.2 or less at 10 GHz, a moisture absorption of 1.5 wt% or less, and a tensile strength of 4.2 GPa. As above, the glass transition temperature (Tg) is 310° C. or higher, and the electronic device for high-speed transmission including the polyimide film can implement high-speed communication at a high frequency of 10 GHz.

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

<Production Example 1> Preparation of the first polyamic acid solution

While injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection/discharging pipe, 415 g of DMF was added and the temperature of the reactor was set to 30°C. After that, 60.63 g of BPDA as an aromatic dianhydride monomer and 22.84 as an aromatic diamine monomer. It was confirmed that it was completely dissolved by adding g of PPD. After the stirring was continued for 120 minutes while heating by raising the temperature to 40°C in a nitrogen atmosphere, a first polyamic acid solution having a solid content of 17% by weight and a viscosity of 2,000 cP at 23°C was prepared.

At this time, the weight average molecular weight of the first polyamic acid measured by GPC (manufactured by Tosoh, HLC-8220GPC) was 15,000 g/mole.

<Production Example 2> Preparation of the second polyamic acid solution

While injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection/discharging pipe, 415 g of NMP was added and the temperature of the reactor was set to 30°C. It was confirmed that it was completely dissolved by adding g of CHDA. After the stirring was continued for 120 minutes while heating by raising the temperature to 40°C in a nitrogen atmosphere, a second polyamic acid solution having a solid content of 17% by weight and a viscosity of 2,000 cP at 23°C was prepared.

At this time, the weight average molecular weight of the second polyamic acid measured by GPC (manufactured by Tosoh, HLC-8220GPC) was 15,000 g/mole.

<Production Example 3> Preparation of a third polyamic acid solution

While injecting nitrogen into a 1000 ml reactor equipped with a stirrer and a nitrogen injection/discharging pipe, the temperature of the reactor was set to 30°C, and then 349.03 g of the first polyamic acid solution of Preparation Example 1 and the second polyamic acid solution of Preparation Example 2 149.51 g, and PMDA 1.27g was heated to 40° C. in a nitrogen atmosphere and stirred for 120 minutes, followed by heating, to prepare a third polyamic acid solution having a solid content of 17% by weight and a viscosity of 200,000 cP at 23°C. I did.

At this time, the weight average molecular weight of the third polyamic acid measured by GPC (manufactured by Tosoh, HLC-8220GPC) was 100,000 g/mole, and the molar ratio of the first polyamic acid and the second polyamic acid was 7:3.

<Comparative Preparation Example 1> Preparation of polyamic acid solution

While injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection/discharging pipe, 415 g of NMP was added and the temperature of the reactor was set to 30°C. After that, 44.87 g of BPDA as an aromatic dianhydride monomer and 18.02 as an aromatic diamine monomer. g of PPD was added, and 14.51 g of HPMDA as an aliphatic dianhydride monomer and 7.46 g of CHDA as an aliphatic diamine monomer were added to confirm that it was completely dissolved. After the stirring was continued for 120 minutes while heating by raising the temperature to 40° C. in a nitrogen atmosphere, a polyamic acid solution having a solid content of 17% by weight and a viscosity of 200,000 cP at 23°C was prepared.

At this time, the weight average molecular weight of the polyamic acid measured by GPC (manufactured by Tosoh, HLC-8220GPC) was 100,000 g/mole.

<Comparative Preparation Example 2> Preparation of mixed polyamic acid solution

While injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection/discharging pipe, 415 g of NMP was added and the temperature of the reactor was set to 30°C. After that, 60.50 g of BPDA as an aromatic dianhydride monomer and 24.37 as an aromatic diamine monomer. It was confirmed that it was completely dissolved by adding g of PPD. The first polyamic acid solution having a solid content of 17% by weight and a viscosity of 200,000 cP at 23° C. was prepared after the stirring was continued for 120 minutes while heating by raising the temperature to 40° C. in a nitrogen atmosphere.

At this time, the weight average molecular weight of the first polyamic acid measured by GPC (manufactured by Tosoh, HLC-8220GPC) was 100,000 g/mole.

Subsequently, 415 g of DMF was added while injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection/discharging pipe, and the temperature of the reactor was set to 30°C. As an aliphatic dianhydride monomer, 56.15 g of HPMDA and aliphatic diamine monomer As, 28.69 g of CHDA was added to confirm that it was completely dissolved. After the stirring was continued for 120 minutes while heating by raising the temperature to 40° C. in a nitrogen atmosphere, a second polyamic acid solution having a solid content of 17% by weight and a viscosity of 200,000 cP at 23°C was prepared.

At this time, the weight average molecular weight of the first polyamic acid measured by GPC (manufactured by Tosoh, HLC-8220GPC) was 100,000 g/mole.

Next, a mixed polyamic acid solution was prepared by mixing the first polyamic acid solution and the second polyamic acid solution prepared above.

<Example 1> Preparation of polyimide film

40 g of the third polyamic acid solution prepared in Preparation Example 3 was used as a precursor composition, and air bubbles were removed by rotating the precursor composition at a high speed of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. Thereafter, a gel film was prepared by drying in a nitrogen atmosphere and at a temperature of 120° C. for 30 minutes, and the gel film was heated to 450° C. at a rate of 2° C./min, heat-treated at 450° C. for 60 minutes, and then until 30° C. Cooling at a rate of 2°C/min to obtain a polyimide film. Thereafter, the polyimide film was peeled off from the glass substrate by dipping in distilled water.

The prepared polyimide film had a molar ratio of 7: 3 and a thickness of 15 µm between the first unit block including the first polyimide resin and the second unit block including the second polyimide resin. The thickness of the prepared polyimide film was measured using an Anritsu's Electric Film thickness tester.

<Example 2>

In Preparation Examples 1 and 2, a polyimide film was prepared in the same manner as in Example 1, except that the weight average molecular weights of the first polyamic acid and the second polyamic acid were respectively changed as shown in Table 1 below.

<Example 3>

In Preparation Examples 1 and 2, a polyimide film was prepared in the same manner as in Example 1, except that the weight average molecular weights of the first polyamic acid and the second polyamic acid were respectively changed as shown in Table 1 below.

<Example 4>

A polyimide film was prepared in the same manner as in Example 1, except that the weight average molecular weight of the third polyamic acid in Preparation Example 3 was changed as shown in Table 1 below.

<Example 5>

In Preparation Example 3, a polyimide film in the same manner as in Example 1, except that the amounts of the first polyamic acid and the second polyamic acid were adjusted so that the molar ratio of the first unit block and the second unit block is as shown in Table 1 below. Was prepared.

<Example 6>

In Preparation Examples 1 and 2, a polyimide film was prepared in the same manner as in Example 1, except that the weight average molecular weights of the first polyamic acid and the second polyamic acid were respectively changed as shown in Table 1 below.

<Example 7>

In Preparation Examples 1 and 2, a polyimide film was prepared in the same manner as in Example 1, except that the weight average molecular weights of the first polyamic acid and the second polyamic acid were respectively changed as shown in Table 1 below.

<Comparative Example 1>

In Preparation Example 3, a polyimide film in the same manner as in Example 1, except that the amounts of the first polyamic acid and the second polyamic acid were adjusted so that the molar ratio of the first unit block and the second unit block is as shown in Table 1 below. Was prepared.

<Comparative Example 2>

In Preparation Example 3, a polyimide film in the same manner as in Example 1, except that the amounts of the first polyamic acid and the second polyamic acid were adjusted so that the molar ratio of the first unit block and the second unit block is as shown in Table 1 below. Was prepared.

<Comparative Example 3>

In Preparation Example 3, a polyimide film in the same manner as in Example 1, except that the amounts of the first polyamic acid and the second polyamic acid were adjusted so that the molar ratio of the first unit block and the second unit block is as shown in Table 1 below. Was prepared.

<Comparative Example 4>

40 g of the polyamic acid solution prepared in Comparative Preparation Example 1 was used as a precursor composition, and air bubbles were removed by rotating the precursor composition at a high speed of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. Thereafter, a gel film was prepared by drying in a nitrogen atmosphere and at a temperature of 120° C. for 30 minutes, and the gel film was heated to 450° C. at a rate of 2° C./min, heat-treated at 450° C. for 60 minutes, and then until 30° C. Cooling at a rate of 2°C/min to obtain a polyimide film. Thereafter, the polyimide film was peeled off from the glass substrate by dipping in distilled water.

The prepared polyimide film had a molar ratio of 7: 3 and a thickness of 15 µm between the first unit block including the first polyimide resin and the second unit block including the second polyimide resin.

<Comparative Example 5>

40 g of the mixed polyamic acid solution prepared in Comparative Preparation Example 2 was used as a precursor composition, and air bubbles were removed by rotating the precursor composition at a high speed of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. Thereafter, a gel film was prepared by drying in a nitrogen atmosphere and at a temperature of 120° C. for 30 minutes, and the gel film was heated to 450° C. at a rate of 2° C./min, heat-treated at 450° C. for 60 minutes, and then until 30° C. Cooling at a rate of 2°C/min to obtain a polyimide film. Thereafter, the polyimide film was peeled off from the glass substrate by dipping in distilled water.

The prepared polyimide film had a molar ratio of 7: 3 and a thickness of 15 µm between the first unit block including the first polyimide resin and the second unit block including the second polyimide resin.

Molar ratio of the first unit block and the second unit block Weight average molecular weight of the first polyamic acid
(g/mol) Weight average molecular weight of the second polyamic acid
(g/mol) Weight average molecular weight of the third polyamic acid
(g/mol) Example 1 7: 3 12,000 12,000 100,000 Example 2 7: 3 15,000 15,000 100,000 Example 3 7: 3 10,000 10,000 100,000 Example 4 7: 3 12,000 12,000 150,000 Example 5 8: 2 12,000 12,000 100,000 Example 6 7: 3 7,000 7,000 100,000 Example 7 7: 3 20,000 20,000 100,000 Comparative Example 1 5: 5 12,000 12,000 100,000 Comparative Example 2 9.5: 0.5 12,000 12,000 100,000 Comparative Example 3 9: 1 12,000 12,000 100,000 Comparative Example 4 - - - 100,000 Comparative Example 5 7: 3 100,000 100,000 -

<Experimental Example 1> Evaluation of moisture absorption and dielectric constant

For the polyimide films each prepared in Examples 1 to 7, Comparative Examples 1 to 5, the moisture absorption and dielectric constant were measured in the following manner, and the results are shown in Table 2 below.

(1) moisture absorption rate measurement

According to the ASTMD 570 method, a polyimide film was cut into a square having a size of 5 cm ㅧ 5 cm to prepare a specimen, and the cut specimen was dried in an oven at 50° C. for at least 24 hours, and then the weight was measured, and the weight was measured. After immersing in water at 23° C. for 24 hours, the weight was measured again, and the difference in weight obtained here was expressed in% to measure the moisture absorption.

(2) dielectric constant measurement

The permittivity at 10 GHz was measured using Keysight's SPDR meter.

Moisture absorption
(weight%) permittivity
(Dk) Example 1 One 3.1 Example 2 0.9 3.0 Example 3 1.2 3.2 Example 4 1.0 3.1 Example 5 1.5 3.2 Example 6 1.3 3.2 Example 7 0.8 3.0 Comparative Example 1 0.8 2.8 Comparative Example 2 2.7 3.5 Comparative Example 3 2.3 3.5 Comparative Example 4 2.0 3.3 Comparative Example 5 2.3 3.4

<Experimental Example 2> Evaluation of tensile strength and glass transition temperature

For the polyimide films each prepared in Examples 1 to 7, Comparative Examples 1 to 5, tensile strength and glass transition temperature were measured in the following manner, and the results are shown in Table 3 below.

(1) Tensile strength measurement

Tensile strength was measured by the method presented in KS6518.

(2) Glass transition temperature measurement

As for the glass transition temperature (T _g ), the loss modulus and storage modulus of each film were calculated using DMA, and the inflection point was measured as a glass transition degree in the tangent graph.

The tensile strength
(GPa) Tg
(℃) Example 1 4.8 311 Example 2 5 315 Example 3 4.6 310 Example 4 4.8 313 Example 5 5.5 322 Example 6 4.2 310 Example 7 5.2 317 Comparative Example 1 3.8 283 Comparative Example 2 7.1 338 Comparative Example 3 6.8 331 Comparative Example 4 3.2 294 Comparative Example 5 7 281

Referring to Tables 2 and 3, it can be seen that in the case of embodiments satisfying the scope of the present invention, moisture absorption and dielectric constant are low, and both heat resistance and mechanical properties are excellent. On the other hand, it can be seen that the comparative examples outside the scope of the present invention do not satisfy at least one of moisture absorption, dielectric constant, heat resistance, and mechanical properties.

Although the above description has been made with reference to the embodiments of the present invention, a person of ordinary skill in the field to which the present invention belongs will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (15)

As a method of producing a polyimide film,
(a) polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent to prepare a first polyamic acid;
(b) polymerizing a dianhydride monomer and a diamine monomer in a second organic solvent to prepare a second polyamic acid, wherein at least one of the dianhydride monomer and diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine monomer ;
(c) preparing a third polyamic acid by copolymerizing the first polyamic acid and the second polyamic acid in a third organic solvent;
(d) preparing a precursor composition comprising a third polyamic acid; And
(e) including the process of imidizing the precursor composition after forming a film on a support,
A method for producing a polyimide film, wherein the first polyamic acid and the second polyamic acid are copolymerized in a molar ratio of 8:2 to 6:4 to prepare a third polyamic acid. The method of claim 1,
The weight average molecular weight of the first polyamic acid and the second polyamic acid is 6,000 to 60,000 g/mole, a method for producing a polyimide film. The method of claim 1,
The method for producing a polyimide film, wherein the third polyamic acid has a weight average molecular weight of 100,000 g/mole or more. delete The method of claim 1,
The aromatic dianhydride monomers include pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride. Including at least any one selected from the group consisting of (BTDA),
The aliphatic dianhydride monomer is 1,2,4,5-cyclohexanetetracarboxylicdianhydride (HPMDA), 2,2-bis[4-(3,4dicarboxyphenoxy)phenyl]propanedianhydride (BPADA), bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylicdianhydride (BOCA), and cyclobutane-1,2,3,4-tetra Carboxylic dianhydride (CBDA) comprising at least any one selected from the group consisting of, a method for producing a polyimide film. The method of claim 1,
The aromatic diamine monomer is 1,4-phenylenediamine (PPD), 4,4'-oxydianiline (ODA), 3,4'-oxydianiline, 4,4'-methylenedianiline (MDA), and Including at least any one selected from the group consisting of 1,3-bis (4-aminophenoxy) benzene (TPE-R),
The aliphatic diamine monomers include cyclohexanediamine (CHDA), 1,4-cyclohexanebis (methylamine), 2,2-bis[(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[ 4-(4-aminophenoxyphenyl)]hexafluoropropane (HFBAPP), 4,4'-methylenebiscyclohexylamine (MCA), 4,4'-methylenebis(2-methylcyclohexylamine) (MMCA ), 1,3-diaminoadamantane (DAA), and 3,3'-diamino-1,1'-diadamantane (DADA) comprising at least any one selected from the group consisting of, polyimide film Method of manufacturing. The method of claim 1,
The first to third organic solvents are N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL ) And Diglyme (Diglyme) comprising at least any one selected from the group consisting of, a method for producing a polyimide film. As a polyimide film comprising a polyimide copolymer prepared by imidizing a polyamic acid copolymer,
The polyimide copolymer includes a first unit block and a second unit block,
The first unit block is an imidized structure of a first polyamic acid prepared by polymerization of an aromatic dianhydride monomer and an aromatic diamine monomer,
The second unit block is an imidized structure of a second polyamic acid prepared by polymerizing a dianhydride monomer and a diamine monomer, and at least one of the dianhydride monomer and diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine Is a monomer,
A polyimide film in which the molar ratio of the first unit block and the second unit block is 8:2 to 6:4. The method of claim 8,
The weight average molecular weight of the first unit block and the second unit block is 6,000 to 60,000 g/mole, a polyimide film. The method of claim 8,
A polyimide film having a weight average molecular weight of 100,000 g/mole or more of the polyimide copolymer. The method of claim 8,
The first unit block and the second unit block are respectively represented by the following Formula 1 and Formula 2, a polyimide film:
[Formula 1]

Here, n is an integer of 20 or more and 150 or less.
[Formula 2]

Here, m is an integer of 20 or more and 150 or less. delete The method of claim 8,
The structure derived from the aliphatic dianhydride monomer or the aliphatic diamine monomer contained in the second unit block is 10 to 30% by weight based on the total weight of the polyimide copolymer, a polyimide film. The method of claim 8,
The polyimide film has a dielectric constant of 3.2 or less, a moisture absorption of 1.5 wt% or less, a tensile strength of 4.2 Gpa or more, and a glass transition temperature of 310° C. or more. An electronic device for high-speed transmission comprising the polyimide film according to claim 8.