KR102138704B1 - Polyimide Film Comprising Bismaleimide Resin and Carbon Black and Method for Preparing The Same - Google Patents

Abstract

The present invention provides a polyimide film comprising a polyimide resin, 5 parts by weight or more of bismaleimide-based resin and carbon black based on 100 parts by weight of the polyimide resin.

Description

Polyimide film containing bismaleimide-based resin and carbon black and its manufacturing method {Polyimide Film Comprising Bismaleimide Resin and Carbon Black and Method for Preparing The Same}

The present invention relates to a polyimide film comprising a bismaleimide-based resin and carbon black and a method for manufacturing the same.

Polyimide (PI) is a polymer material with thermal stability based on a rigid aromatic backbone, and has excellent mechanical strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of the imide ring.

In addition, polyimide is highly regarded as a highly functional material that can be used in microelectronics and optical fields based on excellent electrical properties such as insulation properties and low dielectric constant.

Examples of the microelectronic field include highly integrated circuits included in portable electronic devices and communication devices. The polyimide can be used as a film that is attached to or added to a circuit to provide electrical insulation to the circuit, while protecting the circuit against moisture, light sources, and shocks.

Various examples of the film for protecting the circuit may exist, but in the case of a composite film having an adhesive layer formed on one or both sides of the film, it may be referred to as a coverlay in a narrow sense. It can be preferably used for the coverlay.

Recently, as the visual security of the circuit, the shielding function and the light shielding function have been highlighted, a special polyimide film containing carbon black and having a black tint has been spotlighted as a material for the coverlay.

In order to prepare a polyimide film having a black color tone, a process of mixing and evenly dispersing carbon black in a precursor polyamic acid is essential. In this process, if the carbon black is not evenly distributed, problems such as deterioration of the shielding function or surface defects may occur. In essence, carbon black has different physical/chemical properties from polyamic acid or polyimide, making it difficult to mix and/or disperse in polyimide or polyamic acid.

In addition, the manufacturing process of the circuit may include a drill process, a plating process, a desmear process, and a cleaning process, and the polyimide film may be exposed to the basic solution during the above process. At this time, if the polyimide film is slightly decomposed or denatured by the basic solution, the carbon black contained therein may be largely eliminated.

For this reason, the shielding property may be lost along with the removal of black color from the coverlay, and the weight and thickness may be reduced as well as the surface due to the fall off of the carbon black, and thus the function as a coverlay may be significantly reduced.

Therefore, there is a high need for a technology that can fundamentally solve these problems.

An object of the invention is to provide a polyimide film and a method for manufacturing the same.

According to one aspect of the present invention, the polyimide film includes bismaleimide-based resin and carbon black, and is prepared to contain a desirable content of bismaleimide-based resin and a desirable content of carbon black.

In this aspect, the bismaleimide-based resin can improve the miscibility and/or dispersibility of carbon black in polyamic acid, which is a precursor of the polyimide film.

In addition, even if inevitable denaturation or decomposition is caused in the polyimide film by a basic solution or the like, the bismaleimide-based resin may be useful for suppressing the fall of carbon black.

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.

In one embodiment, the present invention provides a polyimide film comprising a polyimide resin, 5 parts by weight or more of bismaleimide-based resin and carbon black based on 100 parts by weight of the polyimide resin.

In one embodiment, the present invention provides a method of making the polyimide film.

In one embodiment, the present invention provides a coverlay comprising the polyimide film and an electronic device including the coverlay.

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

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

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

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

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

“Diamine” as used herein is intended to include precursors or derivatives thereof, which may not technically be diamines, but will nevertheless react with dianhydrides to form polyamic acids, which are polyamic The acid can be converted back to polyimide.

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 that can be formed with preferred values and any lower range limits or desirable 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.

Polyimide film

The polyimide film according to the present invention,

Polyimide resin;

Bismaleimide-based resin of 5 parts by weight or more with respect to 100 parts by weight of the polyimide resin; And

Carbon black.

In general, polyimide is vulnerable to base components such as decomposition or denaturation when exposed to a base environment. In addition, it can be said that polyimide films containing carbon black are not only difficult to manufacture, but also more vulnerable to base components due to the dropping of carbon black as described above. Therefore, there is a need to improve the'basic resistance' of polyimide films, especially polyimide films comprising carbon black.

Basic resistance means that the polyimide film is not easily decomposed and/or denatured even when exposed to a base environment, and since the thickness of the polyimide is reduced during decomposition and/or modification, the basic resistance is judged based on the thickness reduction. can do.

In this regard, one example for evaluating basic resistance is a method of exposing a polyimide film to a basic solution and measuring a change in thickness of the film before and after exposure. In the present invention, as a method for evaluating the basicity of a polyimide film, a test method (a) is defined as follows. The test method (a) can include the following steps:

Corona treatment on both sides of the polyimide film;

After laminating a polyimide film, a bonding sheet, and a copper foil in order, using a hot press, bonding under a pressure of 50 kgf at a temperature of 160° C. for 30 minutes, followed by cutting to 4*10 cm to prepare a flexible circuit board sample; And

After measuring the thickness of the flexible circuit board sample, measuring the thickness after exposing the same sample to a 10% NaOH solution at 50°C for 100 minutes.

The thickness reduction rate by the test method (a) can be represented by calculating the thickness change after exposure to the thickness of the flexible circuit board sample measured before exposure to NaOH solution as a percentage. That is, the thickness reduction rate can be seen as a quantitative value for basic resistance.

For a conventional polyimide film comprising carbon black, the thickness reduction rate by test method (a) may be approximately 35% to 45%. For reference, a thickness reduction rate exceeding 30% may be judged to be a degree that commercialization of the polyimide film is substantially difficult.

On the other hand, the polyimide film of the present invention containing a bismaleimide-based resin together with carbon black may have a thickness reduction rate by test method (a) of 30% or less, specifically 28% or less, and more specifically 26% or less. And improved base resistance compared to conventional polyimide films.

This will be demonstrated in more detail through'the specific contents for carrying out the invention', but it is presumed that the bismaleimide resin is present in the polyimide film in at least one state selected from the following.

(A) First state coated on the surface of carbon black;

(B) a second state physically bound to the polymer chain of the polyimide resin; And

(C) A third state chemically bound to the polymer chain of the polyimide resin.

The first state facilitates mixing and/or dispersion of carbon black in polyamic acid, which is a precursor of the polyimide film. This can advantageously act on the manufacturing processability of polyimide containing carbon black.

When the mixing and/or dispersion of carbon black is not easy, there may be the following problems. In terms of manufacturing processability, when the carbon black is not evenly dispersed and is concentrated in a part, there may be a problem that a surface defect of the film is caused by forming a protruding portion in the filming process. In terms of basic resistance, a large drop of carbon black may occur due to decomposition or modification of the polyimide resin when exposed to a base component at a site where carbon black is concentrated. In addition, when the carbon black is concentrated in a part, the content of the carbon black is relatively low in other parts except for the part, and a problem that the shielding performance is deteriorated when viewed as a whole of the polyimide film may occur.

Carbon black tends not to be easily dispersed upon simple mixing with polyamic acid. On the other hand, the bismaleimide-based resin may be relatively miscible with polyamic acid. Therefore, the above-described problem can be solved by the first state in which the carbon black can be considered to be encapsulated by a bismaleimide-based resin.

Bismaleimide-based resins are also known as resins having excellent chemical resistance. The bismaleimide-based resin dispersed in the polyimide film together with the carbon black greatly decomposes and/or denatures the polyimide resin by the base component between the carbon black and the polyimide resin based on the excellent chemical resistance inherent therein. Can be suppressed.

In addition, the bismaleimide-based resin tends to have low hygroscopicity, which may delay the phenomenon that the base component penetrates into the polyimide film or help reduce the penetration amount of the base component. Accordingly, the first state can minimize, for example, the dropout of carbon black due to the base component, which can effectively act to improve the basic resistance of the polyimide film.

In other words, the bismaleimide-based resin can act primarily to lower the moisture absorption rate of the polyimide film, and by lowering the moisture absorption rate, delay and/or inhibit the penetration of base components, etc., which can promote the decomposition of the polyimide resin in addition to moisture. It can also help.

Accordingly, the polyimide film of the present invention may have a moisture absorption rate of less than 2%.

In the second state, at least a part of the bismaleimide-based resin may be physically entangled with the polymer chain of the polyimide resin. Also, the bismaleimide-based resin may interfere with the penetration of the base component, and may effectively act to improve the basicity of the polyimide film.

In the second state, the bismaleimide-based resin may also serve to fix the carbon black to the polymer chain of the polyimide resin. Accordingly, the content of the bismaleimide-based resin and thus the expression of the second state is a base component. It can act positively to minimize the fall of carbon black.

In the third state, at least a part of the bismaleimide-based resin is chemically bound to at least a part of the polymer chain of the polyimide resin, and may provide similar advantages to the second state.

As such, the polyimide film of the present invention comprising a bismaleimide-based resin together with carbon black may have improved basic resistance based on the above-described advantages.

However, despite the above advantages, it is not desirable to contain a large amount of bismaleimide resin unconditionally.

Specifically, when the content of the bismaleimide-based resin is at a certain level, the above advantages may be exhibited, but if it exceeds, the mechanical properties of the polyimide film may be rapidly deteriorated. That is, it is important that an appropriate amount of bismaleimide resin is included so that the mechanical properties of the polyimide film are compatible with the above advantages.

Accordingly, in the present invention, the bismaleimide-based resin may be included in 5 parts by weight to 10 parts by weight based on 100 parts by weight of the polyimide resin. This will be clearly demonstrated later, but only when the content of the bismaleimide-based resin is selected within a limited range can the above advantages be expressed and the mechanical properties of the polyimide film reach the desired level. Emphasize again.

The bismaleimide-based resin that can be used in the present invention is not limited to, 4,4'-bismaleimidodiphenylmethane, 2,4-bismaleimidotoluene 4,4-methylene diphenylene, 4,4' -Dicyclohexyl methane and at least one monomer selected from the group consisting of 1,3'-phenylene bismaleimide may be a polymerized resin. However, this is only an example to help the practice of the invention, and it is of course possible to use materials known in the art in consideration of desired properties and effects.

The carbon black may be included in 1 to 10 parts by weight based on 100 parts by weight of the polyimide resin. Within this range, the polyimide film of the present invention containing carbon black may have a light transmittance of 5% or less in a visible light region.

When it is less than the above range, the light transmittance increases, so that the polyimide film cannot have a desired level of shielding property, and when it exceeds the above range, a part of carbon black may aggregate and cause defects on the film surface. In addition, the excessively contained carbon black may negatively affect the mechanical properties of the polyimide film.

The average particle diameter of the carbon black may be 0.1 μm to 5 μm.

When the average particle diameter exceeds or falls below the above range, the same harmful effect as the content of the preceding carbon black may occur.

Meanwhile, the polyimide resin of the present invention may be derived from polyamic acid. The polyamic acid may be a polymer of a dianhydride monomer and a diamine monomer.

Detailed examples of the dianhydride monomers and diamine monomers will be described in detail in the embodiments described later.

The polyimide resin of the present invention may also further include a filler for improving its physical properties or processability. Detailed examples thereof will be described in detail in the embodiments described later.

Manufacturing method of polyimide film

The method for producing the polyimide film of the present invention,

Preparing a first composition by mixing a first organic solvent, carbon black, and bismaleimide-based resin;

Preparing a second composition comprising a polyamic acid by mixing and polymerizing a dianhydride monomer and a diamine monomer in a second organic solvent;

Preparing a precursor composition by mixing the first composition and the second composition; And

It may include the step of imidizing the precursor composition to obtain a polyimide film.

Here, by separately performing the step of preparing the first composition, carbon black and bismaleimide resin in the polyimide film may be induced to exist in at least one state selected from the following:

(A) First state coated on the surface of carbon black;

(B) a second state physically bound to the polymer chain of the polyimide resin; And

(C) A third state chemically bound to the polymer chain of the polyimide resin.

Preferably, the bismaleimide-based resin in the polyimide film may be induced to exist in the first state coated on the surface of the carbon black by separately performing the step of preparing the first composition.

Meanwhile, the step of preparing the first composition may be performed by a milling process. For the milling, the use of a bead milling method can be considered without limitation. Bead milling has the advantage of being able to stir effectively even when the flow rate of the mixture is low, thereby dispersing carbon black. However, it should be understood that this is only an example to help the invention.

A non-limiting example of a first organic solvent that can be used in the step of preparing the first composition is a solvent capable of dispersing carbon black, but a solvent capable of dissolving polyamic acid when mixed with the second composition, in particular, non-positive It may be a magnetic polar solvent (aprotic polar solvent).

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.

The step of preparing the second composition will be described in detail.

The polyamic acid may be prepared by polymerization of one or more diamine monomers and one or more dianhydride monomers in an organic solvent.

The diamine monomer that can be used for the polymerization of the polyamic acid is an aromatic diamine, and can be exemplified by classifying as follows.

1) 1,4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzo Diamines having one benzene ring in the structure, such as diacid (or DABA), etc., which have a relatively rigid structure in diamine;

2) Diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or oxidianiline, ODA) and 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (Methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl )-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane , 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzanilide, 3,3' -Dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine), 2,2'-dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxy Benzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenylsulfide, 3,4' -Diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone , 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4' -Dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(3- Aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodi Diamines having two benzene rings in structure, such as phenyl sulfoxide and 4,4'-diaminodiphenyl sulfoxide;

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

4) 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4-aminophenoxy)phenyl]ether, bis[4- (3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3-(3-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy Si)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[3-(3-aminophenoxy)phenyl]sulfide , Bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3- (3-aminophenoxy)phenyl]sulfone, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy Si)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl Methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4 -Aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane( BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(4- Aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3 ,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, etc., structure Diamine with four phase benzene rings. These can be used alone or in combination of two or more as desired.

The dianhydride monomer that can be used for the polymerization of the polyamic acid may be an aromatic tetracarboxylic dianhydride.

The aromatic tetracarboxylic dianhydride is pyromellitic dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (or s-BPDA), 2,3 ,3',4'-biphenyltetracarboxylic dianhydride (or a-BPDA), oxydiphthalic dianhydride (or ODPA), diphenylsulfone-3,4,3',4'-tetracar Bixyl dianhydride (or DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3, 3-hexafluoropropane dianhydride, 2,3,3',4'- benzophenone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (Or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimelitic Monoester acid anhydride), p-biphenylenebis (trimeric monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p -Terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3, 4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyl phenoxy)phenyl Propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-(2, 2-hexafluoroisopropylidene)diphthalic acid dianhydride and the like. These can be used alone or in combination of two or more as desired.

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

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 second organic solvent that can be particularly preferably used for preparing the second composition of the present invention may be amide solvents N,N'-dimethylformamide and N,N'-dimethylacetamide.

The method for polymerizing the polyamic acid is, for example,

(1) a method in which the total amount of the diamine monomer is placed in an organic 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 an organic 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 an organic solvent, after mixing some components of the dianhydride monomer with respect to the reaction component in a ratio of about 95 mol% to 105 mol%, the remaining diamine monomer components are added thereto. A method in which the remaining dianhydride monomer components are added successively to make the diamine monomer and the dianhydride monomer substantially equimolar;

(4) After placing the dianhydride monomer in an organic solvent, after mixing some components of the diamine compound with respect to the reaction component in a ratio of 95 mol% to 105 mol, other dianhydride monomer components are added and successively the remaining diamine A method of polymerization by adding a monomer component such that the diamine monomer and the dianhydride monomer become substantially equimolar; And

(5) Some diamine monomer components and some dianhydride monomer components are reacted in an excess amount in an organic solvent to form a first polymer, and some diamine monomer components and some dianhydride monomer components are formed in another organic solvent. As a method for reacting such that one is in excess to form a second polymer, mixing the first and second polymers and completing the polymerization, wherein the diamine monomer component is excessive when forming the first polymer. , In the case of the second polymerized product, an excess of the dianhydride monomer component, and in the case of the excess of the dianhydride monomer component in the first polymerized product, in the second polymerized product, the diamine monomer component is added in excess, and the first and second polymerized products are mixed. And a method in which all diamine monomer components and dianhydride monomer components used in these reactions are substantially equimolar and polymerized.

However, the above method is an example for helping the implementation of the present invention, and the scope of the present invention is not limited to them, and any known method can be used.

The polyamic acid prepared as described above may have a weight average molecular weight of 150,000 g/mole or more to 1,000,000 g/mole or less, and more specifically 260,000 g/mole or more to 700,000 g/mole or less, and more specifically 280,000 g/mole It may be greater than or equal to 500,000 g/mole or less.

Polyamic acid having such a weight average molecular weight may be preferable for the production of a polyimide film having better heat resistance and mechanical properties.

In general, the weight average molecular weight of the polyamic acid can be proportional to the viscosity of the precursor composition containing the polyamic acid and the organic solvent, and the viscosity can be adjusted to control the weight average molecular weight of the polyamic acid to the above range.

This is because the viscosity of the precursor composition is proportional to the content of the polyamic acid solid content, specifically, the total amount of the dianhydride monomer and the diamine monomer used in the polymerization reaction. However, the weight average molecular weight does not represent a linear linear relationship with respect to viscosity, but is proportional to the logarithmic function.

In other words, while increasing the viscosity to obtain a higher weight average molecular weight polyamic acid, the range in which the weight average molecular weight can be increased is limited, whereas when the viscosity is too high, the precursor composition is discharged through a die in the film forming process of the polyimide film. At this time, it may cause a processability problem due to an increase in pressure inside the die.

Accordingly, the second composition of the present invention may include 15% to 20% by weight of a polyamic acid solid content and 80% to 85% by weight of an organic solvent, and in this case, a viscosity of 90,000 cP or more to 300,000 cP or less, in detail May be 100,000 cP or more to 250,000 cP. Within this viscosity range, the weight average molecular weight of the polyamic acid may fall within the above range, and the second composition may not cause problems in the film forming process described above.

Meanwhile, a filler may be added during the production of the polyamic acid for the purpose of improving various properties of the film such as sliding property, thermal conductivity, conductivity, corona resistance, and loop hardness of the polyimide film derived from the second composition. . The filler added is not particularly limited, and preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, dibasic calcium phosphate, barium sulfate, and calcium carbonate.

The average particle diameter of the filler is not particularly limited, and can be determined depending on the characteristics of the polyimide film to be modified and the type of filler to be added. In one example, the filler may have an average particle diameter of 0.05 μm to 100 μm, specifically 0.1 μm to 75 μm, more preferably 0.1 μm to 50 μm, and particularly specifically 0.1 μm to 25 μm.

If the average particle diameter is less than this range, the modification effect is negligible, and if it exceeds this range, the filler may significantly impair the surface properties of the polyimide film or cause mechanical properties of the film to deteriorate.

In addition, the addition amount of the filler is not particularly limited, and can be determined by the characteristics of the polyimide film to be modified, the filler particle size, and the like.

In one example, the amount of filler added is from 0.01 to 100 parts by weight, preferably from 0.01 to 90 parts by weight, and more preferably from 0.02 to 80 parts by weight relative to 100 parts by weight of the precursor composition.

If 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, mechanical properties of the polyimide film may be greatly deteriorated. The method for adding the filler is not particularly limited, and any known method can be used.

On the other hand, imidization of the step of obtaining the polyimide film may include casting the precursor composition on a support and drying it to prepare a gel film, followed by imidizing the gel film to form a polyimide film. have.

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, and examples thereof include the following non-limiting examples. This will be described 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

It may include a process of obtaining a polyimide film by heat-treating the gel film.

Here, the gel film can be understood as a film intermediate having self-supporting properties in an intermediate step for the 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. Then, a gel film can be obtained by peeling from the support.

In some cases, a process of stretching the gel film may be performed to adjust the thickness and size of the polyimide film obtained in the subsequent heat treatment process and to improve the orientation, and the stretching may be performed in a machine conveying direction (MD) and a machine conveying 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, and the like remaining in the gel film. 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 400° C. to 650° 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.

<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 polyamic acid, and examples of non-limiting examples include aliphatic acid anhydride, aromatic acid anhydride, and N,N'. -Dialkyl carbodiimide, halogenated lower aliphatic, halogenated lower 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 thereof 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. 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.

The addition amount of the dehydrating agent is preferably in the range of 0.5 to 5 mol with respect to 1 mol of the amic acid group in the polyamic acid, and particularly preferably in the range of 1.0 mol to 4 mol. Further, the amount of the imidizing agent added 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 is 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 previous chemical imidization method.

In the process of forming the gel film, a precursor composition containing a dehydrating agent and/or an imidizing agent is cast in a film form on a support such as a glass plate, 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 to adjust the thickness and size of the polyimide film obtained in the subsequent heat treatment process and to improve the orientation, and the stretching may be performed in a machine conveying direction (MD) and a machine conveying 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 300°C, to remove water, catalyst, residual solvent, etc. remaining in the gel film, By imidizing almost all 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 650° 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.

The polyimide film according to the present invention has been sufficiently described above that the basic resistance can be improved by including a bismaleimide-based resin together with carbon black.

In summary, the bismaleimide-based resin may be relatively miscible with polyamic acid, and when coated on carbon black, it may facilitate mixing and/or dispersion of carbon black in polyamic acid.

The bismaleimide-based resin is also excellent in chemical resistance, on the basis of which it is possible to suppress decomposition and/or denaturation of the polyimide resin by the base component between the carbon black and the polyimide resin.

In addition, the bismaleimide-based resin may delay the phenomenon that the base component penetrates into the polyimide film or reduce the amount of penetration of the base component based on its hygroscopicity.

The manufacturing method according to the present invention has practical advantages to enable the implementation of the above-described polyimide film.

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.

<Example 1>

Preparation Example 1-1: Preparation of the first composition

As a bismaleimide-based resin, 0.21 g of Evonik's'Compimide 200' and 71.45 g of carbon black were mixed with 213.42 g of DMF, and then introduced into a bead milling machine to prepare a first composition.

At this time, the average particle diameter of carbon black was 0.4 µm.

For convenience, the addition amounts of bismaleimide and carbon black are summarized in parts by weight relative to 100 parts by weight of the polyimide resin, and are shown in Table 1 below.

Preparation Example 1-2: Preparation of the second composition

In a 1L reactor, 652.00 g of DMF was added under a nitrogen atmosphere.

After setting the temperature to 25° C., 70.84 g of ODA was added as a diamine monomer, and after stirring for about 30 minutes to confirm that the monomer was dissolved, 77DA. The amount of input was adjusted and added.

After the addition, the mixture was stirred for 1 hour while maintaining the temperature to prepare a second composition containing polyamic acid polymerized to a final viscosity of 250,000 cP.

Preparation Example 1-3: Preparation of polyimide film

25.73 g of the second composition prepared in Preparation Example 1-2 was mixed with 1.22 g of the first composition prepared in Preparation Example 1-1, and 1.31 g of isoquinoline (IQ) as a catalyst (dehydrating agent and imidizing agent), After adding 6.20 g of acetic anhydride (AA) and 4.44 g of DMF, uniformly mixing, casting to 70 μm using a doctor blade on a SUS plate (1000SA, Sandvik), and a temperature range of 100° C. to 200° C. It was dried in.

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

The film was heated from 200°C to 600°C in a high-temperature tenter, cooled at 25°C, and then separated from a pin frame to prepare a polyimide film having a thickness of about 13 μm.

<Example 2> to <Example 4>

A polyimide film having a thickness of about 13 μm was prepared in the same manner as in Example 1, except that the addition amount of the carbon black and bismaleimide-based resin was changed as shown in Table 1 below to prepare the first composition according to Production Example 1-1. Did.

<Comparative Example 1>

Except for the addition of the bismaleimide-based resin, the addition amount of carbon black was changed as shown in Table 1, and the thickness of about 13 µm was the same as in Example 1, except that the first composition was prepared according to Preparation Example 1-1. A polyimide film was prepared.

<Comparative Example 2> to <Comparative Example 7>

Each of the polyimide films having a thickness of about 13 μm was prepared in the same manner as in Example 1, except that the amount of the carbon black and the bismaleimide-based resin was changed as shown in Table 1 below to prepare the first composition according to Preparation Example 1-1. It was prepared.

Carbon black
(Parts by weight) Bismaleimide resin
(Parts by weight) Example 1 One 5 Example 2 3 7 Example 3 5 9 Example 4 7 10 Comparative Example 1 3 0 Comparative Example 2 One One Comparative Example 3 7 3 Comparative Example 4 0.3 One Comparative Example 5 0.5 0.5 Comparative Example 6 12 3 Comparative Example 7 7 15

<Experimental Example 1: Basic resistance test>

The polyimide films prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were tested for basic resistance according to the test method (a) described above, and the thickness reduction rate of each polyimide film was calculated. It is shown in Table 2 below (the first thickness is the thickness before being supported in the NaOH solution, and the second thickness is the thickness after being supported in the NaOH solution).

1st thickness
(㎛) 2nd thickness
(㎛) Thickness reduction rate
(%) Example 1 13 9.1 30 Example 2 12.5 9 28 Example 3 13.2 9.76 26 Example 4 12.3 9.35 24 Comparative Example 1 13 7.8 40 Comparative Example 2 13 7.93 39 Comparative Example 3 13 8.19 37 Comparative Example 4 12.5 8 36 Comparative Example 5 13 8.19 37 Comparative Example 6 13 8.58 34

As shown in Table 2, examples in which the bismaleimide-based resin was included in the scope of the present invention showed relatively excellent basic resistance.

On the other hand, Comparative Example 1, which does not contain a bismaleimide-based resin, showed the lowest basic resistance, which proves that the inclusion of a bismaleimide-based resin plays a major role in improving basic resistance.

In addition, it can be seen that the comparative examples containing too little amount of the bismaleimide resin outside the scope of the present invention have poor basic resistance compared to the examples.

<Experimental Example 2: moisture absorption rate test>

Polyimide films of Examples 1 to 4 and Comparative Examples 1 to 6 were cut into squares of size 5 cm * 5 cm according to ASTMD 570 method to prepare specimens, and the cut specimens were ovend at 50°C. After drying for 24 hours or more, the weight was measured, and after immersing the weighed specimen in water at 23° C. for 24 hours, the weight was measured again, and the difference in weight obtained was expressed in% to measure the moisture absorption rate. The results are shown in Table 3 below.

Moisture absorption rate
(%) Example 1 1.7 Example 2 1.3 Example 3 1.5 Example 4 1.4 Comparative Example 1 3.0 Comparative Example 2 2.5 Comparative Example 3 2.3 Comparative Example 4 2.6 Comparative Example 5 2.7 Comparative Example 6 2.2

As a result of Example 2, examples in which carbon black and a bismaleimide-based resin were included in the scope of the present invention exhibited relatively excellent moisture absorption.

On the other hand, Comparative Example 1, which did not contain a bismaleimide resin, showed the lowest moisture absorption.

On the other hand, it can be seen that at least one of the carbon black and bismaleimide-based resins has a poor hygroscopicity in comparative examples included in excessive or small amounts outside the scope of the present invention.

<Experimental Example 3: Light transmittance test>

The light transmittance of the polyimide film was measured by the method set forth in ASTM D1003 in the visible light region using the HunterLab's ColorQuesetXE model, and the results are shown in Table 4.

However, polyimide films of Examples 1 to 4 and Comparative Examples 4 to 6, which can causally discriminate the change in light transmittance according to the carbon black content, were performed.

Light transmittance
(%) Example 1 5 Example 2 3 Example 3 One Example 4 0.5 Comparative Example 4 50 Comparative Example 5 30 Comparative Example 6 20

As a result of Example 3, Examples incorporating carbon black into the scope of the present invention exhibited a very good moisture absorption rate.

On the other hand, Comparative Examples 4 to 6 in which carbon black was included too little outside the scope of the present invention showed remarkably high light transmittance.

<Experimental Example 4: Tensile strength test>

Tensile strength tests were performed on the polyimide films of Examples 1 to 4 and Comparative Example 7. Tensile strength was measured by the method presented in KS6518. The results are shown in Table 5 below.

The tensile strength
(kgf/cm ² ) Example 1 230 Example 2 230 Example 3 225 Example 4 225 Comparative Example 7 170

From the results of Experimental Example 4, it can be seen that the comparative example 7 in which the bismaleimide-based resin was excessively included outside the scope of the present invention had very poor tensile strength. On the other hand, although Examples 1 to 4 include bismaleimide-based resins, they exhibited good tensile strength.

From the above results, it can be seen that the polyimide film of the present invention is compatible with mechanical properties, advanced basic resistance, hygroscopicity, and light transmittance at desired levels.

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

Claims (16)

Polyimide resin;
5 parts by weight to 10 parts by weight of bismaleimide-based resin relative to 100 parts by weight of the polyimide resin; And
A polyimide film comprising carbon black,
The bismaleimide resin is present in at least one state selected from:
(A) First state coated on the surface of carbon black;
(B) a second state physically bound to the polymer chain of the polyimide resin; And
(C) a third state chemically bound to the polymer chain of the polyimide resin,
A polyimide film having a thickness reduction rate of 30% or less by the test method (a) and a moisture absorption rate of less than 2% measured by the ASTMD 570 method:
Here, the test method (a)
Corona treatment on both sides of the polyimide film;
After laminating the polyimide film, the bonding sheet, and the copper foil in order, using a hot press, bonding under a pressure of 50 kgf at a temperature of 160° C. for 30 minutes, followed by cutting to 4*10 cm to prepare a flexible circuit board sample; And
And measuring the thickness of the flexible circuit board sample, and then measuring the thickness after exposing the same sample to a 10% NaOH solution at 50°C for 100 minutes. delete According to claim 1,
The polyimide film containing the carbon black in 1 part by weight to 10 parts by weight based on 100 parts by weight of the polyimide resin. According to claim 1,
Polyimide film having an average particle diameter of the carbon black is 0.1 ㎛ to 5 ㎛. delete According to claim 1,
The bismaleimide-based resin is 4,4'-bismaleimidodiphenylmethane, 2,4-bismaleimidotoluene 4,4-methylene diphenylene, 4,4'-dicyclohexylmethane and 1, A polyimide film which is a resin in which at least one monomer selected from the group consisting of 3'-phenylene bismaleimide is polymerized. According to claim 1,
The polyimide resin is derived from polyamic acid,
The polyamic acid is a polyimide film in which a dianhydride monomer and a diamine monomer are polymerized. According to claim 1,
A polyimide film having a light transmittance of 5% or less in the visible light region. delete delete As a method for manufacturing the polyimide film according to claim 1,
Preparing a first composition by mixing a first organic solvent, carbon black, and bismaleimide-based resin;
Preparing a second composition comprising a polyamic acid by mixing and polymerizing a dianhydride monomer and a diamine monomer in a second organic solvent;
Preparing a precursor composition by mixing the first composition and the second composition; And
The method comprising the step of obtaining a polyimide film by imidizing the precursor composition. The method of claim 11,
The manufacturing method of the first composition is performed by a milling process. The method of claim 11,
The second composition further includes at least one filler selected from the group consisting of silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, calcium phosphate, barium sulfate, and calcium carbonate. Manufacturing method. The method of claim 11,
The imidization is a method of manufacturing comprising casting the precursor composition onto a support and drying it to produce a gel film, followed by imidizing the gel film to form a polyimide film. A coverlay comprising the polyimide film according to claim 1. An electronic device comprising the coverlay according to claim 15.