KR20200058881A - Polyimide Film Having Low Permittivity and Low Hygroscopicity And Manufacturing Method thereof - Google Patents

Abstract

The present invention provides a method for manufacturing a polyimide film. The method comprises the processes of: (a) preparing a first polyamic acid by polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent; (b) preparing a second polyamic acid by polymerizing a dianhydride monomer and a diamine monomer in a second organic solvent, wherein at least one of the dianhydride monomer and the 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 containing a third polyamic acid; and (e) forming a membrane of the precursor composition on a support and carrying out imidization.

Description

Polyimide film having low dielectric constant and low hygroscopicity and its manufacturing method {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 for manufacturing the same.

In recent years, the introduction of high-level information transmission technology to network these electronic devices along with the high performance and high functionality of computers and communication devices is progressing rapidly, and as part of this, the amount of information transmitted to communication devices constituting such electronic devices or networks. With the increase of signal, the frequency of the signal for speeding up the processing and transmission technology is progressing.

In the past, high-frequency signals of 1 MHz or higher were 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. Development of high-speed transmission electronic devices capable of high-speed communication with high-frequency signals has been actively conducted.

In order to realize such high-frequency high-speed communication, it is required to overcome the problem of signal delay or transmission loss occurring in components (for example, circuit boards for high-speed transmission) of electronic devices mounted in communication equipment. Specifically, the signal delay (RC delay) is expressed as the product of the capacitance (Cacitance, C) and the wiring resistance (resistance, R) between the 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 of, there are problems such as delay of the entire signal transmission due to propagation delay or crosstalk noise. In addition, transmission loss is divided into conductor loss and dielectric loss, which are proportional to the dielectric constant and dielectric loss tangent of the insulator, and tend to increase as the frequency increases.

That is, the high-frequency characteristics of high-speed transmission electronic devices are closely related to the dielectric properties of the insulating layer. Therefore, the use of an insulating material having a very low dielectric constant is essential for high-frequency high-speed communication. Conventionally, a substrate using a fluorine resin (PTFE), which is known as the resin having the highest high-frequency characteristics among polymer materials, was standardized in MIL (Military Specifications and Standards) in 1975 and used for aerospace, space, and military applications. However, since PTFE is a thermoplastic resin having a glass transition temperature near room temperature, it lacks dimensional stability to heat, has poor mechanical strength or thermal conductivity, requires a special plating pretreatment process, and is also moldable (350 ° C). (High temperature above) and processability.

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

In general, a 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 a high temperature by ring dehydration. Since it is based on an imide ring that has excellent chemical stability along with a strong aromatic backbone, it is a polymer material with the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials. In addition to being relatively stable in the region and having an advantage of high breakdown voltage, it has been spotlighted as an insulating material for high-speed communication electronic devices.

However, since the polyimide itself has a high moisture absorption rate due to the nature of the material, despite the excellent physical properties as described above, there is a certain limitation on the expression of a low dielectric constant. Research into low dielectric constant and low dielectric loss tangent as corresponding electrical characteristics has been actively conducted.

For example, in an attempt to lower the dielectric constant of a polyimide resin, 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 in which the fluorine resin powder has a fluorine atom A fluorine resin-containing polyimide composition and a method of manufacturing the polyimide are uniformly dissolved in an organic polar solvent capable of dissolving the aromatic polyimide, but a polyimide containing a fluorine-containing surfactant or the like is proposed. Due to the effect of the fluorine-based resin, the dielectric constant or dielectric loss tangent can be reduced to some extent, but surfactants or dispersants containing fluorine generally increase the dielectric constant and dielectric loss tangent, and it is difficult to sufficiently improve the electrical properties. There are limits.

On the other hand, in order to lower the dielectric constant, a technique has been proposed to include both an aromatic polyimide and an aliphatic polyimide in a polyimide film molecule. However, in the conventional polyimide production method, the characteristics of the aromatic polyimide and the aliphatic polyimide are distinguished. There were limitations in simultaneously realizing 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.

In addition, although the aromatic monomers constituting the aromatic polyimide and the aliphatic monomers constituting the aliphatic polyimide have different reaction characteristics with respect to the solvent, a problem in the process has been caused because they are not conventionally used separately.

Therefore, it is necessary to develop a polyimide film manufacturing method and a polyimide film produced therefrom, which can exhibit a low dielectric constant in a high frequency band (eg, 10 GHz or more) while maintaining excellent natural and thermal properties of the polyimide. to be.

An object of the present invention is to provide a polyimide film and a method of manufacturing the polyimide that exhibits low dielectric constant and low hygroscopicity while maintaining excellent mechanical and thermal properties of the polyimide.

According to an aspect of the present invention, the polyimide film production method comprises the steps of preparing a first polyamic acid by polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent, and a second dianhydride monomer and diamine monomer. The 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 a process that is an aliphatic dianhydride monomer or an aliphatic diamine monomer.

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

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

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

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

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

(b) preparing a second polyamic acid by polymerizing the dianhydride monomer and the diamine monomer in a second organic solvent, wherein at least one of the dianhydride monomer and the 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 on a support, it provides a method for producing a polyimide film, including a process of imidizing.

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 a structure obtained by imidizing a first polyamic acid prepared by polymerization of an aromatic dianhydride monomer and an aromatic diamine monomer,

The second unit block is a structure obtained by imidizing a second polyamic acid prepared by polymerizing a dianhydride monomer and a diamine monomer, and at least one of the dianhydride monomer and the diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine A polyimide film, which is a monomer, is provided.

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

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

Prior to this, the terms or words used in the present specification and claims should not be interpreted as being limited to ordinary or dictionary meanings, and the inventor appropriately explains the concept of terms in order 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 this specification, a singular expression includes a plural expression unless the context clearly indicates otherwise. In this specification, the terms "comprises", "haves" 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.

<Method for manufacturing polyimide film>

The method for producing a polyimide film according to the present invention comprises the steps of (a) polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent to produce a first polyamic acid;

(b) preparing a second polyamic acid by polymerizing the dianhydride monomer and the diamine monomer in a second organic solvent, wherein at least one of the dianhydride monomer and the 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 on a support, characterized in that it comprises a process of imidizing.

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

The polyimide chain formed by imidizing 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 the aromatic unit structure, the polyimide film according to the present invention can express excellent mechanical and thermal properties of the polyimide as it is.

In another specific example, the aliphatic dianhydride monomer is 1,2,4,5-cyclohexanetetracarboxydianhydride (HPMDA), 2,2-bis [4- (3,4dicarboxyphenoxy) Phenyl] propanedianhydride (BPADA), bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic didianhydride (BOCA), and cyclobutane-1,2 , 3,4-tetracarboxylic didianhydride (CBDA).

In addition, the aliphatic diamine monomer is, for example, cyclohexanediamine (CHD), 2,2-bis [(4-aminophenoxy) phenyl] propane (BAPP), 2,2-bis [4- (4-amino Phenoxyphenyl)] hexafluoropropane (HFBAPP), 4,4'-methylenebiscyclohexylamine (MCA), 4,4'-methylenebis (2-methylcyclohexylamine) (MMCA), 1,3- Diaminoadamantane (DAA), 3,3'-diamino-1,1'-diaadamantane (DADA), isophorone diamine, 4,4'-diaminodicyclohexylmethane (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). In detail, it 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, 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).

The polyimide chain formed by imidizing 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 -CH ₃ , -CF ₃ , as a non-limiting example of the structure derived from the aliphatic monomer. Chain aliphatic hydrocarbon group and cyclic aliphatic hydrocarbon group And the like.

This will be described in more detail later, but the structure derived from such an aliphatic monomer exhibits non-polarity, whereby the polyimide film according to the present invention can exhibit low moisture absorption. In another aspect, since the structure derived from the aliphatic monomer is included in the second polyamic acid, it is possible to relatively lower the proportion of the amic acid group causing an increase in hygroscopicity, thereby positively lowering the moisture absorption rate of the polyimide film produced therefrom. Can work.

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

Moreover, as in the conventional polyamic acid production method, for example, when an aromatic dianhydride monomer, an aromatic diamine monomer, an aliphatic dianhydride monomer and an aliphatic diamine monomer are simultaneously added to prepare a polyamic acid, in the polyimide chain produced therefrom A structure derived from an aromatic monomer that exhibits excellent mechanical and thermal properties and a structure derived from an aliphatic monomer that exhibits a low moisture absorption rate are not generated, and thus there may be a problem that a polyimide film in which these properties are simultaneously expressed cannot be produced.

On the other hand, in the case of the manufacturing method according to the present invention, in order to effectively express the excellent properties of the respective monomers, the process of preparing the first polyamic acid by polymerizing the aromatic dianhydride monomer and the aromatic diamine monomer in the first organic solvent and Dianhydride monomers and diamine monomers are polymerized in a second organic solvent to produce a second polyamic acid, and at least one of the dianhydride monomers and diamine monomers is an aliphatic dianhydride monomer or an aliphatic diamine monomer. , The polyimide film produced therefrom can simultaneously implement excellent mechanical, thermal 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, specifically 7,000 to 20,000 g / mole, and more specifically 10,000 to 15,000 g / mole, more specifically 12,000 to 15,000 g / mole.

When the weight average molecular weight of the first polyamic acid and the second polyamic acid exceeds the above range, a disadvantage of a structure derived from an aromatic monomer in a polyimide chain prepared therefrom, such as a high dielectric constant and high moisture absorption, may be highlighted. , The disadvantages of structures derived from aliphatic monomers, such as deterioration in mechanical and thermal properties, may be highlighted, which is not preferred.

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 monomers of the polyimide chain prepared therefrom, as in the conventional manufacturing method of preparing the polyamic acid by simultaneously introducing the monomers It is not preferable because the excellent mechanical and thermal properties of the derived structure and the low dielectric constant and low moisture absorption of the structure derived from the aliphatic monomer are not simultaneously expressed.

That is, in the present invention, after the polymerization of the first polyamic acid and the second polyamic acid to have a certain molecular weight, so that the excellent properties of each of the aromatic monomer-derived structure and the aliphatic monomer-derived structure are highlighted, and their disadvantages do not appear. , It is a technical feature of polymerizing the first polyamic acid and the second polyamic acid to prepare a third polyamic acid and imidizing the polyimide film.

At this time, 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 that the viscosity of the precursor composition containing the third polyimide acid increases, which is when the precursor composition is moved through the pipe during the manufacturing process of the polyimide film. Since higher pressure must be applied by friction with the pipe, process cost may be increased and handling may be deteriorated. In addition, the higher the viscosity, the more time and cost may be required for the mixing process.

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

Conversely, when the weight-average molecular weight of the third polyamic acid is less than the above range, the effect of the present invention that highlights the excellent physical properties of the first polyamic acid and the second polyamic acid cannot be exerted.

Meanwhile, the 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 specifically 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 contained in the polyimide chain is relatively very low, so Dielectric and low moisture absorption characteristics can be difficult to develop.

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 excess, the content of the structure derived from the aliphatic monomer contained in the polyimide chain prepared therefrom is too high. , The mechanical and thermal properties of the polyimide film may be deteriorated.

The production of polyamic acid 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 in a ratio of about 95 to 105 mol%, the remaining diamine monomer components are added thereto, followed by 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, after mixing some components of the diamine compound with respect to the reaction component in a ratio of 95 to 105 mol%, 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 diamine monomer components and some dianhydride monomer components are reacted in an excessive amount to form a first composition, and some diamine monomer components and some dianhydride monomer components are formed in another solvent. A method of reacting such that one is excessive to form a second composition, and then mixing the first and second compositions and completing polymerization. In this case, when the diamine monomer component is excessive when forming the first composition, the second In the composition, if the dianhydride monomer component is excessive, and if the dianhydride monomer component is excessive in the first composition, in the second composition, the diamine monomer component is excessive, and the first and second compositions are mixed to perform these reactions. A method in which all diamine monomer components and dianhydride monomer components used are substantially equimolar and polymerized; And the like.

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

The polymerization method is not limited to the above examples, and it is needless to say that any known method can 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 as an example, they may be aprotic polar solvents.

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 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 controlled by using auxiliary solvents such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, and water.

In one example, the organic solvent that can be particularly preferably used for the first organic solvent and the third organic solvent may be amide 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 a film such as sliding property, thermal conductivity, conductivity, corona resistance, and loop hardness. The filler to be added is not particularly limited, and preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

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

When the particle diameter is less than this range, a modification effect is unlikely to appear, and when it exceeds this range, surface properties may be greatly impaired, or mechanical properties may be significantly deteriorated.

In addition, the addition amount of the filler is not particularly limited, and may be determined by film characteristics to be modified, filler particle diameter, and 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.

When the amount of the filler added is less than this range, the modification effect by the filler is unlikely to appear, and if it exceeds this range, there is a possibility that the mechanical properties of the film are significantly impaired. The method for adding the filler is not particularly limited, and any known method can be used.

As a method for producing a polyimide film by imidizing the precursor composition prepared as described above, a conventionally known method can be used.

Specific examples of the imidization method include a thermal imidization method, a chemical imidization method, or a complex imidization method using a combination of the thermal imidization method and a chemical imidization method. Examples of the imidization method include the following non-limiting examples. This will be explained in more detail.

<Thermal imidization method>

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.

Drying the precursor composition to form a gel film; And

The 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, aluminum foil, endless stainless belt, or stainless drum, and then the precursor composition on the support is 50 ° C to 200 ° C, Specifically, it may be to dry 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 the formed gel film may be peeled from the support to obtain a gel film.

In some cases, a process of stretching the gel film may be performed in order to control the thickness and size of the polyimide film obtained in the subsequent heat treatment process and to improve the orientation, and the stretching is performed in the machine transport direction (MD) and the machine transport direction. It may be performed in at least one of the lateral direction for (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, residual solvent, etc. remaining in the gel film, and remaining By imidizing almost all the amic acid groups, the polyimide film of the present invention can be obtained.

In some cases, the polyimide film obtained as described above may be heated to a temperature of 300 ° C to 600 ° C for 5 seconds to 400 seconds to further harden the polyimide film, and may remain in the obtained polyimide film. This may be done under a given tension to relieve internal stress.

<Chemical imidation method>

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

Here, the term “dehydrating agent” refers to a substance that promotes a cyclization reaction through dehydration of a polyamic acid, and as a non-limiting example, an aliphatic acid anhydride, an aromatic acid anhydride, N, N ' -Dialkyl carbodiimide, lower halogenated aliphatic, lower halogenated patty acid anhydride, aryl phosphonic dihalide, thionyl halide, and the like. Of these, aliphatic acid anhydrides may be preferred from the viewpoint of ease of availability and cost, and non-limiting examples include acetic anhydride (AA), propionic acid anhydride, and lactic acid anhydride. Etc. are mentioned, These can be used individually or in mixture of 2 or more types.

In addition, "imide agent" means a substance having an effect of promoting a ring-closure reaction to a polyamic acid, for example, an imine-based component such as an aliphatic tertiary amine, an aromatic tertiary amine, and a heterocyclic tertiary amine. Can be. Of these, heterocyclic tertiary amines may be preferable from the viewpoint of reactivity as a catalyst. Non-limiting examples of heterocyclic tertiary amines include quinoline, isoquinoline, β-picoline (BP), pyridine and the like, and these may be used alone or in combination of two or more.

It is preferable that the addition amount of a dehydrating agent is in the range of 0.5 to 5 mol with respect to 1 mol of the amic acid group in polyamic acid, and it is particularly preferable to be in the range of 1.0 mol to 4 mol. Further, the addition amount of the imidizing agent is preferably in the range of 0.05 mol to 2 mol with respect to 1 mol of the amic acid group in the polyamic acid, and particularly preferably in the range of 0.2 mol to 1 mol.

When the dehydrating agent and the imidizing agent fall below the above range, chemical imidization is insufficient, cracks may be formed in the polyimide film to be produced, and mechanical strength of the film may also be lowered. In addition, if these addition amounts exceed the above range, imidization may proceed excessively rapidly, and in this case, it may be difficult to cast in the form of a film or the produced polyimide film may exhibit brittle characteristics, which is not preferable. not.

<Composite imidization method>

In conjunction with the chemical imidization method described above, a complex imidization method in which a thermal imidization method is further performed can be used for the production of a polyimide film.

Specifically, the complex imidization method includes a chemical imidization method in which a dehydrating agent and / or an imidizing agent is added to the precursor composition at a low temperature; And drying the precursor composition to form a gel film and heat-treating the gel film.

When performing the chemical imidization process, the type and amount of dehydrating agent and imidizing agent may be appropriately selected as described in the chemical imidation 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, aluminum foil, endless stainless belt, or stainless drum, and then on the support. The precursor composition is dried at variable temperatures ranging from 50 ° C to 180 ° C, specifically 80 ° C to 180 ° C. In this process, chemical converting agents and / or imidizing agents can act as catalysts to rapidly convert the amic acid groups to imide groups.

In some cases, a process of stretching the gel film may be performed in order to control the thickness and size of the polyimide film obtained in the subsequent heat treatment process and to improve the orientation, and the stretching is performed in the machine transport direction (MD) and the machine transport direction. It may be performed in at least one of the lateral direction for (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 700 ° C, specifically 150 ° C to 600 ° C, to remove water, catalyst, residual solvent, and the like remaining in the gel film, By imidizing most of the remaining amic acid groups, the polyimide film of the present invention can be obtained. In such a heat treatment process, a dehydrating agent and / or an imidizing agent acts as a catalyst, so that the amic acid group can be rapidly converted to an imide group, thereby realizing a high imidization rate.

In some cases, the polyimide film obtained as described above may be heated to a temperature of 400 ° C. to 500 ° C. for 5 seconds to 400 seconds to further harden the polyimide film, and may remain inside the obtained polyimide film. It can also be done under a given tension to relieve 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 a structure obtained by imidizing a first polyamic acid prepared by polymerization of an aromatic dianhydride monomer and an aromatic diamine monomer,

The second unit block is a structure obtained by imidizing a second polyamic acid prepared by polymerizing a dianhydride monomer and a diamine monomer, and at least one of the dianhydride monomer and the 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, specifically 7,000 to 20,000 g / mole, and more specifically 10,000 to 15,000 g / mole, more specifically 12,000 to 15,000 g / mole.

In general, the weight average molecular weights of the first unit block and the second unit block in the polyimide resin state are substantially similar to the weight average molecular weights of the first polyamic acid and the second polyamic acid described above. Depending on the range of the weight average molecular weight, the problems described above 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 : It may be 3 to 6: 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 ratios of the first unit block and the second unit block are also of the first polyamic acid and the second polyamic acid. As the molar ratio may have a value that is substantially very similar, the problems described above may occur depending on their weight average molecular weight or range of molar ratios.

In one specific example, the first unit block and the second unit block may be represented by the following Formula 1 and Formula 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, excellent mechanical and thermal properties of the polyimide film are difficult to express, and below this range, a desired level of dielectric constant and moisture absorption It is difficult to achieve and is not desirable.

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

In this regard, in the case of the polyimide film according to the present invention that satisfies both the conditions of the above (a) permittivity and (b) moisture absorption rate, it can be utilized as an insulating film used in electronic equipment for high-speed transmission, and is 10 GHz or more Even when used as an electrical signal transmission circuit that transmits signals at high frequencies, 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 the above (c) tensile strength and (d) glass transition temperature, it may exhibit excellent mechanical and thermal properties.

Hereinafter, the four conditions will be described in detail.

<Dielectric constant>

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

In the insulator (for example, a polyimide film), + and-moment components, which are normally scattered in random directions, are aligned to alternating changes in the electromagnetic field applied from the outside. That is, by changing the moment components according to the direction of change of the electromagnetic field, it is possible to enable the propagation of electromagnetic waves in the interior as well as the non-conductor.

In response to this change in the external electromagnetic field, the degree to which the moment inside the material reacts sensitively and can be expressed as a dielectric constant, and a high dielectric constant means that electrical energy is well transmitted, so an insulator such as a polyimide film has a dielectric constant. The lower it is, the better.

That is, while the conventional polyimide film has a dielectric constant higher than a level sufficient to maintain sufficient insulation for high-frequency communication, the polyimide film according to the present invention may have a dielectric constant of 3.2 or less at 10 GHz as an example. May be, preferably 3.0 or less, the lower limit may be at least 2.2. It can be seen that this shows 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, there is always a capacitive coupling by an electric field therebetween, so even if the layers and layers of the multi-layer substrate are also electrically separated from each other, this is an open circuit for DC. In fact, it can be seen that a capacitor of some value is connected between them.

At this time, the capacitor has a property that the higher the frequency of the current or voltage at both ends, the lower the impedance, and the value can be expressed by the following equation.

-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 level that is visible and can be handled with bare hands, no matter how close the two conductors are, the capacitance value (farad) between them is difficult to escape from the pico unit, and in general PCBs, the C between layers is similar. It is so small that the insulation between layers can be maintained even if the circuit operates at a certain high frequency, but in the case of electronic devices for high-speed transmission operating at a frequency of GIGA, for example, a high frequency of 10 GHz or more, as in the above formula. Since insulation can be difficult to maintain because the impedance is very low due to the high frequency value, when selecting an insulator, materials with a low dielectric constant, that is, materials with a low dielectric constant, are used 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 a polyimide chain derived from the second polyamic acid. Specifically, the structure derived from the aliphatic monomer has a lower specific gravity, molecular density, polarity, and probability of forming a charge transfer complex than the structure derived from the aromatic monomer, and thus the dielectric constant can be reduced.

Therefore, the polyimide film of the present invention has an advantage of easy insulation retention even in high-speed transmission electronic devices operating at a frequency of GIGA, for example, high frequency of 10 GHz or higher.

<Water absorption rate>

The moisture absorption rate is a ratio indicating the amount of moisture the material is absorbing. It is generally known that the dielectric constant increases when the moisture absorption rate is high, water has a dielectric constant of 100 or more in the solid state, about 80 in the liquid state, and 1.0059 in the gaseous water vapor.

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

Therefore, it can be seen that the low moisture absorption rate is a property that is essential for the polyimide film to be utilized as an insulating film.

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

<Tensile strength>

In the present invention, the tensile strength refers to the resistance until the film reaches fracture when applied to the film. The strength includes bending strength, torsional strength, tensile strength, etc., depending on the method of loading, and these strengths have a certain relationship with tensile strength, and thus can be used as a standard for film strength with tensile strength.

Tensile strength is expressed as GPa, and is the maximum load that has been withstood, 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 elastic modulus and the loss elastic modulus measured by a dynamic viscoelasticity measuring device (DMA). Specifically, the calculated loss elastic modulus divided by the storage elastic modulus is the top peak of tan δ. Can be calculated as the glass transition temperature.

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 temperature and low dielectric constant, because the strong heat resistance of the polyimide film is due to the chemical stability of the imide group, but since the imide group exhibits polarity, it is relative to moisture absorption. It is predicted that it is due to the 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, the polyimide film according to the present invention satisfies all of the above four conditions, and 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, particularly at a high frequency of at least 5 GHz, and more specifically, at 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 method for producing a polyimide film according to the present invention is a process and a process for 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 excellent properties of each monomer. By polymerizing the hydride monomer and the diamine monomer in a second organic solvent to prepare a second polyamic acid, by dividing the process wherein 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 low mechanical and thermal properties while simultaneously achieving low hygroscopic 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 described above, the glass transition temperature (Tg) is 310 ° C or higher, and the high-speed transmission electronic device including the polyimide film can realize high-speed communication at a high frequency of 10 GHz.

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.

<Production Example 1> Preparation of first polyamic acid solution

After introducing nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection / discharge tube, 415 g of DMF was added and the temperature of the reactor was set to 30 ° C., followed by 60.63 g of BPDA and aromatic diamine monomers as aromatic dianhydride monomers 22.84 It was confirmed that it was completely dissolved by adding g of PPD. After heating the mixture to a temperature of 40 ° C. under a nitrogen atmosphere and stirring was continued for 120 minutes, a first polyamic acid solution having a solid content of 17 wt% and a viscosity at 23 ° C. of 2,000 cP 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 second polyamic acid solution

After injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection / discharge tube, 415 g of NMP was added and the temperature of the reactor was set to 30 ° C, followed by 54.56 g of HPMDA as an aliphatic dianhydride monomer and 28.69 as an aliphatic diamine monomer. It was confirmed that gDA was completely dissolved by adding CHDA. After heating the temperature to 40 ° C. under a nitrogen atmosphere and stirring was continued for 120 minutes, a second polyamic acid solution having a solid content of 17 wt% and a viscosity at 23 ° C. of 2,000 cP 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 third polyamic acid solution

After injecting nitrogen into a 1000 ml reactor equipped with a stirrer and a nitrogen injection and discharge 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 149.51 of the second polyamic acid solution of Preparation Example 2 g, and PMDA 1.27 g, heated to 40 ° C. under a nitrogen atmosphere, continued stirring for 120 minutes, and then a third polyamic acid solution having a solid content of 17 wt% and a viscosity at 23 ° C. of 200,000 cP was prepared. 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 between the first polyamic acid and the second polyamic acid was 7: 3.

<Comparative Preparation Example 1> Preparation of polyamic acid solution

After injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection / discharge tube, 415 g of NMP was added, and the temperature of the reactor was set to 30 ° C., followed by 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 complete dissolution. After heating at 40 ° C. under a nitrogen atmosphere and stirring was continued for 120 minutes, a polyamic acid solution having a solid content of 17% by weight and a viscosity at 23 ° C. of 200,000 cP was prepared.

At this time, the weight average molecular weight of 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

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

Subsequently, while introducing nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection / discharge tube, 415 g of DMF was added and the temperature of the reactor was set to 30 ° C., and then 56.15 g of HPMDA and an aliphatic diamine monomer as an aliphatic dianhydride monomer. As 28.69 g of CHDA was added, it was confirmed that it was completely dissolved. After heating the temperature to 40 ° C under a nitrogen atmosphere and stirring was continued for 120 minutes, a second polyamic acid solution having a solid content of 17% by weight and a viscosity at 23 ° C of 200,000 cP 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 from the precursor composition through high-speed rotation of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to a glass substrate using a spin coater. Then, under a nitrogen atmosphere and dried at a temperature of 120 ° C. for 30 minutes, a gel film was prepared, the gel film was heated to a rate of 2 ° C./min to 450 ° C., heat-treated at 450 ° C. for 60 minutes, and up to 30 ° C. Cooling at a rate of 2 ° C / min yielded a polyimide film. Thereafter, the polyimide film was peeled from the glass substrate by dipping in distilled water.

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

<Example 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 in Preparation Examples 1 and 2 were changed as shown in Table 1 below.

<Example 3>

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 in Preparation Examples 1 and 2 were changed as shown in Table 1 below.

<Example 4>

A polyimide film was manufactured 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>

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

<Example 6>

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 in Preparation Examples 1 and 2 were changed as shown in Table 1 below.

<Example 7>

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 in Preparation Examples 1 and 2 were changed as shown in Table 1 below.

<Comparative Example 1>

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

<Comparative Example 2>

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

<Comparative Example 3>

Polyimide film in the same manner as in Example 1, except that the input amounts of the first polyamic acid and the second polyamic acid were adjusted so that the molar ratio between the first unit block and the second unit block in Preparation Example 3 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 through the precursor composition through high-speed rotation of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to a glass substrate using a spin coater. Then, under a nitrogen atmosphere and dried at a temperature of 120 ° C. for 30 minutes, a gel film was prepared, the gel film was heated to a rate of 2 ° C./min to 450 ° C., heat-treated at 450 ° C. for 60 minutes, and up to 30 ° C. Cooling at a rate of 2 ° C / min yielded a polyimide film. Thereafter, the polyimide film was peeled from the glass substrate by dipping in distilled water.

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

<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 through the precursor composition at a high speed of 1,500 rpm or higher. Thereafter, the defoamed polyimide precursor composition was applied to a glass substrate using a spin coater. Then, under a nitrogen atmosphere and dried at a temperature of 120 ° C. for 30 minutes, a gel film was prepared, the gel film was heated to a rate of 2 ° C./min to 450 ° C., heat-treated at 450 ° C. for 60 minutes, and up to 30 ° C. Cooling at a rate of 2 ° C / min yielded a polyimide film. Thereafter, the polyimide film was peeled from the glass substrate by dipping in distilled water.

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

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 -

<Experiment 1> moisture absorption and dielectric constant evaluation

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

(1) Measurement of moisture absorption rate

A specimen was prepared by cutting a polyimide film into squares of 5 cm ㅧ 5 cm in size according to the ASTMD 570 method. 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 moisture absorption.

(2) Dielectric constant measurement

The dielectric constant at 10 GHz was measured using a Keysight SPDR meter.

Moisture absorption rate
(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

<Experiment 2> Tensile strength and glass transition temperature evaluation

For each of the polyimide films prepared in Examples 1 to 7, and 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) Measurement of glass transition temperature

The glass transition temperature (T _g ) was obtained by using the DMA to determine the loss modulus and storage modulus of each film, and the inflection point of these films was measured as the glass transition temperature.

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, in the case of embodiments satisfying the scope of the present invention, it can be confirmed that the moisture absorption and dielectric constant are low, and both heat resistance and mechanical properties are excellent. On the other hand, it can be confirmed 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 described above with reference to embodiments of the present invention, those of ordinary skill in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above.

Claims (15)

As a method for producing a polyimide film,
(a) preparing a first polyamic acid by polymerizing an aromatic dianhydride monomer and an aromatic diamine monomer in a first organic solvent;
(b) preparing a second polyamic acid by polymerizing the dianhydride monomer and the diamine monomer in a second organic solvent, wherein at least one of the dianhydride monomer and the 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 on a support, imidization, a method for producing a polyimide film. According to claim 1,
A method for producing a polyimide film, wherein the first polyamic acid and the second polyamic acid have a weight average molecular weight of 6,000 to 60,000 g / mole. According to claim 1,
A method for producing a polyimide film, wherein the weight average molecular weight of the third polyamic acid is 100,000 g / mole or more. According to claim 1,
A method for producing a polyimide film, wherein a third polyamic acid is prepared by copolymerizing the first polyamic acid and the second polyamic acid in a molar ratio of 8: 2 to 6: 4. According to claim 1,
The aromatic dianhydride monomers include pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), oxydiphthalan hydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA) at least one selected from the group consisting of,
The aliphatic dianhydride monomer is 1,2,4,5-cyclohexanetetracarboxydianhydride (HPMDA), 2,2-bis [4- (3,4dicarboxyphenoxy) phenyl] propanedianhydride (BPADA), bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic didianhydride (BOCA), and cyclobutane-1,2,3,4-tetra A method for producing a polyimide film, comprising at least one selected from the group consisting of carboxylic didianhydride (CBDA). According to claim 1,
The aromatic diamine monomer is 1,4-phenylenediamine (PPD), 4,4'-oxydianiline (ODA), 3,4'-oxydianiline, 4,4'-methylenedianiline (MDA), and 1,3-bis (4-aminophenoxy) benzene (TPE-R) at least one selected from the group consisting of, and
The aliphatic diamine monomer is 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'-diaadamantane (DADA). Method of manufacturing. According to claim 1,
The first to third organic solvents are N, N'-dimethylformamide (DMF), N, N'-dimethylacetamide (DMAc), N-methyl-pyrrolidone (NMP), gamma brothyl lactone (GBL) ) And Diglyme (Diglyme) at least one selected from the group consisting of, polyimide film production method. 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 a structure obtained by imidizing a first polyamic acid prepared by polymerization of an aromatic dianhydride monomer and an aromatic diamine monomer,
The second unit block is a structure obtained by imidizing a second polyamic acid prepared by polymerizing a dianhydride monomer and a diamine monomer, and at least one of the dianhydride monomer and the diamine monomer is an aliphatic dianhydride monomer or an aliphatic diamine A polyimide film that is a monomer. The method of claim 8,
A polyimide film having a weight average molecular weight of 6,000 to 60,000 g / mole of the first unit block and the second unit block. The method of claim 8,
The polyimide film, wherein the polyimide copolymer has a weight average molecular weight of 100,000 g / mole or more. The method of claim 8,
The first unit block and the second unit block are represented by the following Formula 1 and Formula 2, respectively, 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. The method of claim 8,
The polyimide film, wherein 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 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, polyimide film. The method of claim 8,
The polyimide film is a polyimide film having 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. Electronic device for high-speed transmission comprising a polyimide film according to claim 8.