CN114423824B

CN114423824B - Polyimide film having excellent chemical resistance and method for preparing the same

Info

Publication number: CN114423824B
Application number: CN202080065906.5A
Authority: CN
Inventors: 李吉男
Original assignee: Polyimide Advanced Materials Co ltd
Current assignee: Polyimide Advanced Materials Co ltd
Priority date: 2019-09-24
Filing date: 2020-07-20
Publication date: 2023-12-12
Anticipated expiration: 2040-07-20
Also published as: KR20210035550A; CN114423824A; KR102336859B1; WO2021060685A3; WO2021060685A2

Abstract

The present application provides a polyimide film having excellent chemical resistance, which contains at least one aliphatic ring structure having 5 or more carbon atoms, and a method for producing the same.

Description

Polyimide film having excellent chemical resistance and method for preparing the same

Technical Field

The present application relates to a polyimide film and a method for producing the same, and more particularly, to a polyimide film having excellent chemical resistance, which contains at least one aliphatic ring structure having 5 or more carbon atoms, and a method for producing the same.

Background

Polyimide (PI) is a polymer material based on an imide ring having excellent chemical stability with a hard aromatic main chain, and has the highest level of heat resistance, electrical insulation, chemical resistance, weather resistance among organic materials.

In particular, excellent insulating properties, that is, excellent electrical properties such as permittivity, have been attracting attention as high-functional polymer materials in the fields of electric power, electronics, optics, and the like.

Recently, polyimide has been widely used as a cover film (coverlay) for portable electronic devices and communication devices.

The cover film is used for protecting electronic components such as flexible printed circuit boards, lead frames of semiconductor integrated circuits, and the like, and needs to be thin-film, safe, portable, visual, and conceal electronic components or mounted components, and also needs to have appropriate optical characteristics.

In the production of a flexible printed circuit board, a dry film is laminated on a metal foil laminate (in particular, a copper foil laminate) having a metal layer formed on one or both surfaces of a polyimide film, and then a circuit pattern is formed by exposure, development and etching in this order, and after the cover film is tack-welded on the outside of the metal foil laminate, a lamination process by hot pressing is performed.

Wherein the cover film is cut to a prescribed size to protect and insulate the exposed surface of the circuit, unnecessary portions are removed by processing, and then laminated by tack welding on the outside of the metal foil laminate.

On the other hand, when the polyimide film is used as a cover film for a flexible printed circuit board, the cover film formed of the polyimide film is exposed to an alkaline solution through processes such as drilling (drill), electroplating, desmear (desmear), and cleaning.

However, polyimide is generally known to be susceptible to alkali exposure, such as decomposition or denaturation.

Therefore, when a polyimide film is used as a cover film, since it is inevitably exposed to alkali, the polyimide is decomposed or denatured, resulting in a change in the thickness (particularly thinning) of the film or a change in physical properties, resulting in a decrease in the function as a cover film, and there is a problem in that the reliability of a product prepared using the same is significantly reduced.

In order to solve this problem, an attempt has been made to improve chemical resistance by using an aromatic monomer having a large molecular weight, but there are problems in that the heat resistance is poor, it is difficult to prepare a uniform film, and the preparation cost is increased.

In addition, a method of mixing varnishes synthesized with some polymer monomers to improve chemical resistance has been attempted, but there is a limit in improving chemical resistance while maintaining heat resistance.

Therefore, there is a need to develop a polyimide film for a cover film having high chemical resistance while maintaining the characteristics of polyimide itself, and an efficient production method thereof.

The matters described in the foregoing background art are for aiding in the understanding of the background of the application and may include matters not yet known to those skilled in the art.

Prior art literature

Patent literature

Patent document 1: korean laid-open patent publication No. 10-2016-0000232

Disclosure of Invention

Technical problem to be solved by the application

The purpose of the present application is to provide a polyimide film having excellent chemical resistance, which contains at least one aliphatic ring structure having 5 or more carbon atoms, and a method for producing the same.

It is therefore a substantial object of the present application to provide specific embodiments thereof.

Means for solving the technical problems

An embodiment of the present application for achieving the object described above provides a polyimide film comprising: a first polyimide chain prepared by imidizing a first dianhydride component and a first diamine component; and a second polyimide chain produced by imidizing a second dianhydride component and a second diamine component, wherein the first dianhydride component and the second dianhydride component each contain two or more aromatic ring structures, the first diamine component does not contain an aliphatic ring structure in the molecular structure, and the second diamine component contains at least one aliphatic ring structure having 5 or more carbon atoms in the molecular structure.

The first dianhydride component and the second dianhydride component of the polyimide film may each be independently one or more selected from the group consisting of pyromellitic dianhydride (Pyromellitic dianhydride, PMDA), biphenyl tetracarboxylic dianhydride (3, 3', 4' -Biphenyltetracarboxylic dianhydride, BPDA), oxydiphthalic anhydride (4, 4' -Oxydiphthalic anhydride, ODPA), benzophenone tetracarboxylic dianhydride (3, 3', 4' -Benzophenonetetracarboxylic dianhydride, BTDA) and 4,4' -bisphenol a dianhydride (4, 4' -Bisphenol A dianhydride, BPADA), and the first diamine component may be one or more selected from the group consisting of 1,4-Phenylenediamine (PPD), oxydianiline (oxypheniline, ODA), 2-Bis [4- (4-aminophenoxy) phenyl ] propane (2, 2-Bis [4- (4-aminophenoxy) phenyl ] propane, BAPP), 4' -Methylenedianiline (4, 4' -Bisphenol A dianhydride, BPADA), and 1, 4-diaminobenzene (1, 4-phenylene) and 1, 4-Bis (3-phenylene) amide).

The aliphatic ring structure having 5 or more carbon atoms of the polyimide film may be one or more of a substituted or unsubstituted monocyclic (monocylic) structure and a substituted or unsubstituted bicyclic (bicylic) structure.

The weight ratio of the second polyimide chain may be 15 to 30% by weight based on the sum of the weights of the first polyimide chain and the second polyimide chain of the polyimide film.

Still another embodiment of the present application provides a cover film including the polyimide film and an electronic device including the cover film.

Another embodiment of the present application provides a method for preparing a polyimide film, the method comprising: a first step of polymerizing a first polyamic acid from a first dianhydride component and a first diamine component; a second step of polymerizing a second polyamic acid from a second dianhydride component and a second diamine component; and a third step of imidizing the first polyamic acid and the second polyamic acid by mixing them and performing a heat treatment, wherein the first dianhydride component and the second dianhydride component each contain two or more aromatic ring structures, the first diamine component does not contain an aliphatic ring structure in the molecular structure, and the second diamine component contains at least one aliphatic ring structure having 5 or more carbon atoms in the molecular structure.

ADVANTAGEOUS EFFECTS OF INVENTION

As described above, the polyimide film of the present application has excellent chemical resistance as well as excellent thermal, mechanical and electrical properties of the polyimide film itself, and thus can be effectively used in a coverlay film requiring such properties and an electronic device including the coverlay film.

Detailed Description

Hereinafter, embodiments of the present application will be described in further detail in the order of "polyimide film" and "method for producing polyimide film" according to the present application.

Before this, the terms or words used herein and in the scope of the application claimed should not be construed as limited to general or dictionary meanings, but interpreted as meanings and concepts conforming to the technical spirit of the present application on the basis of the principle that the inventor can properly define terms in order to explain his application in the best manner.

Therefore, it should be understood that the structure of the embodiments described herein is only one embodiment among the preferred embodiments of the present application and does not represent all technical spirit of the present application, so various equivalent substitutions and modifications may be made in terms of the present application.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It will be understood that the terms "comprises," "comprising," "includes," "including" or "having," etc., when used herein, are intended to specify the presence of stated features, integers, steps, components, or groups thereof, but do not preclude the presence or addition of one or more other features or integers, steps, components, or groups thereof.

Where an amount, concentration, or other value or parameter is given as either a range, preferred range, or an enumeration of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges which might be formed from any pair of any upper value or preferred value and any lower value or preferred value, regardless of whether ranges are separately disclosed.

When numerical ranges are referred to herein, unless otherwise indicated, the ranges are intended to include the endpoints thereof, and all integers and fractions within the range. The scope of the application is not intended to be limited to the particular values mentioned when defining the scope.

"dianhydride" is herein intended to include precursors or derivatives thereof, which may not be technically dianhydrides, but which also react with diamines to form polyamic acids, which can be reconverted to polyimides.

The polyimide film of the present application comprises a first polyimide chain prepared by imidizing a first dianhydride component and a first diamine component, and a second polyimide chain prepared by imidizing a second dianhydride component and a second diamine component, wherein the first dianhydride component and the second dianhydride component each comprise two or more aromatic ring structures, the first diamine component does not comprise an aliphatic ring structure in the molecular structure, and the second diamine component comprises at least one aliphatic ring structure having 5 or more carbon atoms in the molecular structure.

The first polyimide chain functions to impart rigidity mainly to the polyimide film, and the second polyimide chain functions to impart chemical resistance mainly to the polyimide film.

Since the polyimide film includes the first polyimide chain imparting rigidity and the second polyimide chain imparting chemical resistance, it is possible to simultaneously exhibit excellent thermal properties, mechanical properties, and chemical resistance.

The first dianhydride component and the second dianhydride component may be one or more kinds selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyl tetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA), benzophenone Tetracarboxylic Dianhydride (BTDA) and 4,4' -bisphenol a dianhydride (BPADA), respectively, but are not limited thereto.

In particular, it is preferable that the second dianhydride component is one or more of biphenyl tetracarboxylic dianhydride (BPDA) and 4,4' -bisphenol a dianhydride (BPADA).

The first diamine component may be one or more selected from the group consisting of 1,4-phenylenediamine (PPD), oxodiphenylamine (ODA), 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP), 4' -Methylenediphenylamine (MDA), and 1,3-bis (4-aminophenoxy) benzene (TPE-R), but is not limited thereto.

As the second diamine component, a diamine component having at least one aliphatic ring structure having 5 or more carbon atoms in the molecular structure may be used alone.

The aliphatic ring structure having 5 or more carbon atoms may be one or more of a substituted or unsubstituted aliphatic monocyclic (monocylic) structure and a substituted or unsubstituted bicyclic (bicylic) structure.

Among the aliphatic ring structures having 5 or more carbon atoms, examples of the aliphatic monocyclic structure include cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, and the like, which may be unsubstituted or substituted.

When the aliphatic monocyclic structure is substituted, the substituent may be at least one straight-chain or branched-chain saturated hydrocarbon group having 1 to 4 carbon atoms.

Typical examples of the second diamine component containing at least one of the above-mentioned aliphatic monocyclic structures having 5 or more carbon atoms include Methylenebis (cyclohexylamine) (Methylenebis (cyclohexylamine), PACM, CAS No. 1761-71-3), 4'-Methylenebis (2-methylcyclohexylamine) (4, 4' -methylenbis (2-methylcylohexylamine), MACM, CAS No. 6864-37-5) and the like.

In addition, examples of the aliphatic double ring (bicyclo) structure may include an aliphatic condensed double ring structure (fused bicyclo), an aliphatic bridged double ring structure (bridged bicyclo), an aliphatic spiro double ring structure (spirobicyclic), and the like, which may be unsubstituted or substituted.

Wherein the aliphatic fused bicyclic structure is a structure called bicyclo [ x, y,0] alkane (bicyclo [ x, y,0] alkine, wherein x, y are natural numbers), the aliphatic bridged bicyclic structure is a structure called bicyclo [ x, y, z ] alkane (bicyclo [ x, y, z ] alkine, wherein x, y, z are natural numbers), and the aliphatic spirobicyclo structure (spiro) is a structure called spirobicyclo [ x, y ] alkane (spiro [ x, y ] alkine, wherein x, y are natural numbers).

When the aliphatic double ring (bicyclic) structure is substituted, the substituent may be at least one straight or branched saturated hydrocarbon group having 1 to 4 carbon atoms.

As examples of the aliphatic double-ring structure, it may include bicyclo [3, 0] octane (bicyclo [3, 3] octane), decalin (decaline), norbornane (norbornane), bicyclo [2, 2] octane (bicyclo [2.2.2] octane), bicyclo [3.3.1] nonane (bicyclo [3, 1] non), bicyclo [3.3.3] undecane (bicyclo [3, 3] undecane), spiro [5,5] undecane (spiro [5,5] undecane), and the like.

Typical examples of the second diamine component containing at least one of the aliphatic double ring structures having 5 or more carbon atoms include bis (aminomethyl) norbornane (Bis (aminomethyl) norbonane, CAS No. 56602-77-8) and the like.

These substituted or unsubstituted aliphatic ring structures having 5 or more carbon atoms contribute to improvement of chemical resistance while improving low hygroscopicity of the polyimide film.

The polyimide film having a weight ratio of the second polyimide chain of 15 to 30 wt% has an alkali resistance index of 80% or more based on the total weight of the polyimide chains of the polyimide film (when the sum of the weights of the first polyimide chain and the second polyimide chain is taken as 100 wt%), has excellent chemical resistance, and is thus suitable for use as a coverlay film.

When the weight ratio of the second polyimide chain is less than 15% by weight based on the total weight of the polyimide chain, the alkali resistance index is less than 80%, chemical resistance sufficient for use as a coverlay is not exhibited, and when more than 30% by weight based on the total weight of the polyimide chain, the heat resistance and mechanical physical properties of the polyimide film are reduced, and thus are unsuitable for use as a coverlay film.

Alkali resistance means a property that a polyimide film is not easily decomposed or denatured even if exposed to an alkaline environment, and for the evaluation, a method of measuring the thickness change of the film before and after exposure of the polyimide film to NaOH solution and a detergent solution can be used.

The preparation method of the polyimide film comprises the following steps: a first step of polymerizing a first polyamic acid from a first dianhydride component and a first diamine component; a second step of polymerizing a second polyamic acid from a second dianhydride component and a second diamine component; and a third step of imidizing the first polyamic acid and the second polyamic acid by mixing them and performing a heat treatment, wherein the first dianhydride component and the second dianhydride component each contain 2 or more aromatic ring structures, the first diamine component does not contain an aliphatic ring structure in the molecular structure, and the second diamine component contains at least one aliphatic ring structure having 5 or more carbon atoms in the molecular structure.

In addition, when the second polyamic acid contains 10 wt% of the solid component, the viscosity may range from 1000cP to 5000cP.

When the viscosity of the second polyamic acid is less than or greater than the range, much time is required in the mixing process, so that the processability is lowered, and various defects may occur in the product.

The solvent used for polymerizing the first polyamic acid solution and the second polyamic acid solution is not particularly limited, and any solvent may be used as long as it can dissolve the polyamic acid, and the specific solvent may be an organic polar solvent, specifically, an aprotic polar solvent (aprotic polar solvent), preferably, an amide solvent.

For example, one or more selected from the group consisting of N, N '-Dimethylformamide (DMF), N' -dimethylacetamide, N-methyl-pyrrolidone (NMP), γ -butyrolactone (GBL), diglyme (Diglyme) may be used, but not limited thereto, and two or more may be used singly or in combination as required.

In one example, preferably, as the solvent, N-dimethylformamide and N, N-dimethylacetamide can be used.

In the polymerization step of the polyamic acid, all monomers may be added at once or each monomer may be added in sequence according to the kind of monomers and the physical properties of the polyimide film required, in which case partial polymerization may occur between the monomers.

The dianhydride component and the diamine component may be added in the form of powder (powder), block (lamp) or solution, and preferably, the dianhydride component and the diamine component are added in the form of powder and reacted at the initial stage of the reaction, and the polymerization viscosity is adjusted by adding the dianhydride component and the diamine component in the form of solution.

For example, the dianhydride component is added in a powder form to react with the diamine component, and then the dianhydride is added in a solution form to react until the viscosity of the first polyamic acid or the second polyamic acid is within a predetermined range.

Alternatively, the imidization catalyst may be further added to the first polyamic acid and the second polyamic acid and then applied to the support.

In this case, as the imidization catalyst, a dehydration catalyst composed of an acid anhydride such as acetic anhydride and the like, a tertiary amine such as isoquinoline, β -picoline, pyridine and the like, and the like can be used, and can be used in the form of a mixture of acid anhydride/amine or an acid anhydride/amine/solvent mixture.

The amount of the acid anhydride to be added may be calculated from the molar ratio of the ortho-carboxyamide functional groups (o-carboxylic amide functional group) in the first polyamic acid solution and the second polyamic acid solution, and may be 1.0 mol to 5.0 mol, and the amount of the tertiary amine to be added may be calculated from the molar ratio of the ortho-carboxyamide functional groups in the polyamic acid solution, and may be specifically added to be 0.2 mol to 3.0 mol.

In addition, in the step of heat-treating the polyamic acid solution coated on the support and performing gelation, the gelation temperature condition may be 100 ℃ to 250 ℃.

As the carrier, a glass plate, an aluminum foil, a circulating stainless steel belt, a stainless steel tub, or the like can be used.

The treatment time required for gelation may be 5 minutes to 30 minutes, but is not limited thereto, and may vary depending on the gelation temperature, the type of support, the amount of polyamic acid solution applied, and the mixing conditions of the catalyst.

After the gelled film is separated from the support, heat treatment is performed to complete drying and imidization.

The polyimide film of the present application may be mainly applied to a chemical imidization method or a composite imidization method, but is not limited thereto.

As an example of the chemical imidization method, the dehydrating agent and the imidization catalyst are activated by heat treatment at a temperature ranging from 40 ℃ to 300 ℃, preferably from 80 ℃ to 200 ℃, more preferably from 100 ℃ to 180 ℃, thereby being partially cured and/or dried to form a gel as an intermediate having self-supporting property. Thereafter, it is preferable to include a step of peeling the gel from the support and a step of further heating the gel to imidize and dry the remaining amic acid (amic acid) (hereinafter, also referred to as "firing process").

As an example of the composite imidization method, after a polyamic acid solution is added with a dehydrating agent and an imidization catalyst, it is heated at 80 to 200 ℃, preferably at 100 to 180 ℃, and after being partially cured and dried, it is heated at 200 to 400 ℃ for 5 to 400 seconds, whereby a polyimide resin can be obtained.

The heat treatment temperature may be 10 ℃ to 500 ℃ and the heat treatment time may be 1 minute to 30 minutes. The gelled film may be fixed on a fixable support such as a pin-type frame or clip-type or the like to perform heat treatment when heat-treated.

On the other hand, in the present application, when the polyamic acid is applied (discharged) to the carrier in order to realize the polyimide film, it is necessary to control the process conditions such as the discharge amount, the speed, the pressure, and the like.

Specifically, when it is desired to minimize vibration when the polyamic acid solution is discharged from a T-Die to an Endless Belt (Endless Belt) and landed in a film form, for this purpose, when a discharged film is formed, it is possible to apply a pressure lower than that used in the production of a conventional polyimide film, for example, at 10mmH ₂ O to 40mmH ₂ Air (air) is supplied under pressure of O.

At this time, the amount discharged from the T-die and the velocity of the endless belt may satisfy the following equation, for example, the amount discharged from the T-die may be 150 kg/hour to 300 kg/hour, and the velocity of the endless belt may be 15mpm to 25mpm.

1 (1)

The amount of ejection from the T-die/time of ejection from the T-die = specific gravity of the film (T-die cross-sectional area) (velocity of the endless belt).

At the laboratory level, an ultra-thin thickness of polyimide film can be obtained by adjusting the casting thickness, however, a desired thickness can be achieved when the range is satisfied in a mass production process.

Also, when the heat treatment is performed using a dryer or the like after being fixed to the pin frame, in order to prevent the film from being broken in the heat treatment process, the heat treatment may be performed at a temperature of 50 to 150 ℃ lower than the maximum heat treatment temperature standard when the yellow polyimide film of the same thickness is prepared.

In addition, the imidized film may be thinned by cooling treatment at a temperature of 20 ℃ to 30 ℃.

In addition, in order to improve various properties of the film, such as contact property, thermal conductivity, electric conductivity, corona resistance, loop hardness, etc., when preparing the polyamic acid solution, a filler may be added.

The filler to be added is not particularly limited, but preferable examples thereof include silica, titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, and the like.

The particle diameter of the filler is not particularly limited and may be determined according to the properties of the film to be modified and the kind of filler added.

In general, the average particle diameter may be from 0.05 μm to 100. Mu.m, preferably from 0.1 μm to 75. Mu.m, more preferably from 0.1 μm to 50. Mu.m, particularly preferably from 0.1 μm to 25. Mu.m.

If the particle diameter is smaller than this range, the modifying effect is hardly exhibited, and if the particle diameter is larger than this range, the surface properties may be greatly impaired, and the mechanical properties may be greatly reduced.

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

In general, the filler may be added in an amount of 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, more preferably 0.02 to 80 parts by weight, relative to 100 parts by weight of polyimide.

If the filler addition amount is less than this range, the modification effect due to the filler is hardly exhibited, and if the filler is more than 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.

Hereinafter, the present application will be described in more detail using preparation examples, examples and comparative examples. The following preparation examples, examples and comparative examples are illustrative of the present application, and the scope of the present application is not limited thereto.

< preparation example >

Preparation example 1-1: polymerization of first Polyamic acid

As a first polyamic acid solution polymerization step, 407.5g of dimethylformamide was added as a solvent to a 1L reactor under a nitrogen atmosphere.

After setting the temperature to 25 ℃, 35.1g of Oxydiphenylamine (ODA) and 6.3g of 1,4-phenylenediamine (PPD) were added as diamine monomers, stirred for about 30 minutes, and after confirming the dissolution of the monomers, 51.0g of pyromellitic dianhydride (PMDA) was added in portions, and finally the final addition amount was adjusted and added so that the viscosity became 300000cP from 250000 cP.

After the addition was completed, the mixture was stirred for 1 hour while maintaining the temperature to polymerize the first polyamic acid solution having a final viscosity of 260000 cP.

Preparation examples 1-2: polymerization of the second polyamic acid

As a polymerization step of the second polyamic acid, 450g of dimethylformamide was added as a solvent to a 1L reactor under a nitrogen atmosphere.

After the temperature was set to 25 ℃, 22.45g of 4,4' -methylenebis (2-methylcyclohexylamine) (MACM) was added as a diamine monomer, and stirring was further performed for about 30 minutes, after confirming that the monomer was dissolved, 27.55g of biphenyl tetracarboxylic dianhydride (BPDA) was added, and the mixture was stirred at the maintained temperature for 1 hour, thereby polymerizing a second polyamic acid solution having a viscosity of 4000 cP.

Example 1]

To 100g of the first polyamic acid solution prepared in preparation example 1-1, 35g of the mixture prepared in preparation example 2-1 was mixed, 4.76g of Isoquinoline (IQ), 26.36g of anhydrous Acetic Acid (AA), and 18.87g of DMF as catalysts were added, and after uniform mixing, casting was performed on SUS plate (100 sa, sandvik) to 150 μm using a doctor blade, and drying was performed at a temperature ranging from 100 ℃ to 200 ℃.

Then, the film was peeled off from the SUS plate and fixed on a pin frame, and then transferred to a high temperature tenter.

After heating the film from 200℃to 450℃on a high temperature tenter, cooling at 25℃and separating from the pin frame, a polyimide film having a thickness of 15 μm, which contains 84% by weight of the first polyimide chain and 16% by weight of the second polyimide chain, relative to the total weight of the polyimide film, was produced.

Example 2]

A polyimide film having a thickness of 15 μm, which contained 82% by weight of the first polyimide chain and 18% by weight of the second polyimide chain, relative to the total weight of the polyimide film, was produced in the same manner as in example 1, using 100g of the first polyamic acid solution produced in the production example 1-1 and 40g of the second polyamic acid solution produced in the production example 1-2.

Example 3]

In the same manner as in example 1, a polyimide film having a thickness of 15 μm, which contains 78 wt% of the first polyimide chain and 22 wt% of the second polyimide chain with respect to the total weight of the polyimide film, was prepared using 100g of the first polyamic acid solution prepared in the preparation example 1-1 and 50g of the second polyamic acid solution prepared in the preparation example 1-2.

Example 4 ]

In the same manner as in example 1, a polyimide film having a thickness of 15 μm, which contains 75% by weight of the first polyimide chain and 25% by weight of the second polyimide chain with respect to the total weight of the polyimide film, was prepared using 100g of the first polyamic acid solution prepared in the preparation example 1-1 and 60g of the second polyamic acid solution prepared in the preparation example 1-2.

Comparative example 1]

A polyimide film was prepared using only 100g of the first polyamic acid solution prepared in preparation example 1-1.

Comparative example 2]

In the same manner as in example 1, a polyimide film having a thickness of 15 μm, which contains 68% by weight of the first polyimide chain and 32% by weight of the second polyimide chain with respect to the total weight of the polyimide film, was prepared using 100g of the first polyamic acid solution prepared in the preparation example 1-1 and 85g of the second polyamic acid solution prepared in the preparation example 1-2.

Comparative example 3]

In the same manner as in example 1, a polyimide film having a thickness of 15 μm, which contains 90% by weight of the first polyimide chain and 10% by weight of the second polyimide chain with respect to the total weight of the polyimide film, was prepared using 100g of the first polyamic acid solution prepared in the preparation example 1-1 and 20g of the second polyamic acid solution prepared in the preparation example 1-2.

Experimental example 1: evaluation of tensile Property

For the polyimide films prepared in < examples 1> to < example 4> and < comparative examples 1> to < comparative example 3>, respectively, tensile properties were measured according to ASTM D882 specifications. That is, the tensile strength, elongation and elastic modulus were measured, and the results are shown in table 1 below.

TABLE 1

As shown in table 1, there was a tendency that the elongation increased with a decrease in tensile strength and elastic modulus in tensile properties as the content of the second polyimide chain increased from 16 wt% to 25 wt% in examples 1 to 4.

This trend was also confirmed in comparative example 2 in which the content of the second polyimide chain was higher than the range of examples 1 to 4 and comparative example 3 in which the content of the second polyimide chain was lower than the range of examples 1 to 4.

In examples 1 to 4, a phenomenon of a decrease in tensile strength and elastic modulus and an increase in elongation occurs as compared with comparative example 1, which does not contain the second polyimide chain at all, so that it can be seen that the content of the second polyimide chain imparting chemical resistance also affects the overall tensile strength characteristics of the polyimide film.

Experimental example 2: alkali resistance index evaluation

After the polyimide films prepared in < examples 1> to < 4> and < comparative examples 1> to < 3> respectively were subjected to double-sided corona treatment, a Flexible Copper Clad Laminate (FCCL) sample was prepared by pressing with a Hot Press (Hot Press) at 160 ℃ for 30 minutes at a pressure of 50kgf in a polyimide film+adhesive sheet (adhesive) +copper foil structure and fusing.

FCCL cut into 4 x 10cm was exposed to 10% NaOH solution at 55 ℃ for 3 min and to decontamination solution (10% namno ₄ +4% NaOH) for 5 minutes, the washing process was repeated twice, and the thickness of the film was measured, and the degree of change in the thickness after exposure compared to the thickness before exposure to NaOH solution and detergent solution was shown in the following table 2 as a percentage.

TABLE 2

As shown in table 2, for the polyimide films of examples 1 to 4, when the second polyimide chain having an alkali resistance index of 80% or more and containing 16 to 25% by weight in the content range of the present application was prepared, it was confirmed that the polyimide film had remarkably excellent chemical resistance as compared with comparative example 1 not containing the second polyimide chain.

In addition, the alkali resistance index was 95% for comparative example 2 in which the content of the second polyimide chain was higher than that of examples 1 to 4, and thus it was confirmed that the second polyimide chain had excellent chemical resistance, but the tensile properties were lowered as described in table 1.

In addition, in comparative example 3 in which the content of the second polyimide chain was lower than that of examples 1 to 4, the alkali resistance index was only 72%, and it was confirmed that the chemical resistance was lowered as compared with examples 1 to 4.

Although the embodiments of the present application have been described in detail through the detailed description thereof, those skilled in the art to which the present application pertains can make various applications and modifications within the scope of the present application based on the above description.

Industrial applicability

The polyimide film of the present application has excellent chemical resistance as well as excellent thermal, mechanical and electrical properties of the polyimide film itself, and thus can be effectively used in a coverlay film requiring such properties and an electronic device including the coverlay film.

Claims

1. A polyimide film, wherein,

comprising:

a first polyimide chain prepared by imidizing a first dianhydride component and a first diamine component; and

a second polyimide chain prepared by imidizing a second dianhydride component and a second diamine component,

the first dianhydride component and the second dianhydride component respectively comprise more than two aromatic ring structures,

the first diamine component does not contain an aliphatic ring structure in a molecular structure, the second diamine component is 4,4' -methylenebis (2-methylcyclohexylamine),

wherein the weight ratio of the second polyimide chain is 15 to 30% by weight based on the sum of the weights of the first polyimide chain and the second polyimide chain.

2. The polyimide film according to claim 1, wherein,

the first dianhydride component and the second dianhydride component are each independently at least one selected from the group consisting of pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride, oxydiphthalic anhydride, benzophenone tetracarboxylic dianhydride and 4,4' -bisphenol A dianhydride,

the first diamine component is at least one selected from the group consisting of 1,4-phenylenediamine, oxo-diphenylamine, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 4' -methylenediphenylamine and 1,3-bis (4-aminophenoxy) benzene.

3. The polyimide film according to claim 2, wherein the second dianhydride component is one or more of biphenyl tetracarboxylic dianhydride and 4,4' -bisphenol A dianhydride.

4. The polyimide film according to claim 1, wherein the polyimide film has an alkali resistance index of 80% or more.

5. A coverlay film comprising the polyimide film according to any one of claims 1 to 4.

6. An electronic device comprising the cover film according to claim 5.

7. The preparation method of the polyimide film is characterized by comprising the following steps:

a first step of polymerizing a first polyamic acid from a first dianhydride component and a first diamine component;

a second step of polymerizing a second polyamic acid from a second dianhydride component and a second diamine component; and

a third step of imidizing by mixing the first polyamic acid and the second polyamic acid and performing heat treatment,

8. The method for producing a polyimide film according to claim 7, characterized in that,

9. The method for producing a polyimide film according to claim 7, wherein the polyimide film has an alkali resistance index of 80% or more.