KR102153506B1 - Polyimide Film Comprising Clay Particle and Carbon Black and Method for Preparing The Same - Google Patents

Abstract

The present invention is a polyimide resin; Plate-shaped clay particles; And carbon black, wherein the clay particles are dispersed in the film to form a plurality of barrier layers, and at least a portion of the carbon black is provided between the barrier layers.

Description

Polyimide Film Comprising Clay Particle and Carbon Black and Method for Preparing The Same {Polyimide Film Comprising Clay Particle and Carbon Black and Method for Preparing The Same}

The present invention relates to a polyimide film containing clay particles and carbon black, and a method for producing 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 has been in the spotlight 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 constants.

Examples of the field of microelectronics include highly integrated circuits included in portable electronic devices and communication devices. Polyimide is attached or added to a circuit to provide electrical insulation to the circuit, and can be used as a film to protect the circuit against moisture, light sources, impacts, and the like.

There may be various examples as a film protecting the circuit as described above, but in the case of a composite film in which an adhesive layer is formed on one or both sides of the film, it may be referred to as a coverlay in a narrow sense, and the polyimide film It can be preferably used for the coverlay.

In recent years, as the visual security, shielding function and light-shielding function for circuits have been highlighted, a special polyimide film containing carbon black and having a black color tone has been in the spotlight as a material for coverlays.

However, the manufacturing process of the circuit may include a drill process, a plating process, a desmear process, and a washing process, and the polyimide film may be exposed to a basic solution during the above process.

At this time, if the polyimide film is decomposed or denatured even slightly 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 the black tint from the coverlay, and a reduction in weight and thickness as well as the surface due to the loss of carbon black may be accompanied, so that the function as a coverlay may be significantly deteriorated.

Therefore, there is a high need for a technology that can fundamentally solve this problem.

It is an object of the invention to provide a polyimide film and a method for producing the same.

According to an aspect of the present invention, a polyimide film is prepared to contain clay particles and carbon black.

In this aspect, even if the clay particles included in the polyimide film of the present invention are inevitable denaturation or decomposition of the polyimide film by a basic solution or the like, it may be useful to suppress the loss of carbon black.

In another aspect, the clay particles may help delay the penetration of the base component into the polyimide film, or help reduce the amount of penetration of the base component.

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

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

In one embodiment, the present invention is a polyimide resin;

Plate-shaped clay particles; And

Including carbon black,

The clay particles are dispersed in the film to form a plurality of barrier layers,

At least a portion of the carbon black is provided between the barrier layers, a polyimide film.

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

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

Hereinafter, embodiments of the invention will be described in more detail in the order of “polyimide film” and “manufacturing method of polyimide film” according to the present invention.

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

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

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

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

In the present specification "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but nevertheless will react with dianhydride to form polyamic acid, and this 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 a range, a preferred range, or a preferred upper and lower preferred value, any pair of any upper range limits, or It is to be understood that the preferred values and any lower range limits or all ranges that may be formed with preferred values are specifically disclosed. When a range of numerical values is referred to herein, unless stated otherwise, the range is intended to include its endpoints and all integers and fractions within that range. It is intended that the scope of the invention is not limited to the specific values recited when defining the range.

Polyimide film

Polyimide resin;

Plate-shaped clay particles; And

Including carbon black,

The clay particles are dispersed in the film to form a plurality of barrier layers,

It is characterized in that at least some of the carbon black is located between the barrier layers.

Such a polyimide film will be described in detail below, but the clay particles have the effect of minimizing the penetration of the basic solution, suppressing the inevitable denaturation by the basic solution, and also suppressing the loss of carbon black.

As described above, polyimides are generally vulnerable to basic components such as decomposition or denaturation when exposed to a basic environment.

In addition, the polyimide film containing carbon black is difficult to manufacture, and as described above, it can be said that the polyimide film is more vulnerable to the base component due to the elimination of the carbon black.

The removal of the carbon black may also cause a decrease in light transmittance in the polyimide film comprising the same.

Accordingly, there is a need to improve the'basic resistance' of a polyimide film, particularly a polyimide film including carbon black.

Basic resistance refers to a property that does not easily decompose and/or denature even when the polyimide film is exposed to a basic environment, and the thickness of the polyimide film decreases during the decomposition and/or modification. I can judge.

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, the evaluation method (a) is used as a method for evaluating the basic resistance of the polyimide film.

Evaluation method (a) may include the following steps:

Corona treatment on both sides of the polyimide film;

After sequentially laminating a polyimide film, a bonding sheet, and a copper foil, bonding them under a pressure of 50 kgf at a temperature of 160° C. for 30 minutes using a hot press, and then cutting into 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 according to the evaluation method (a) can be expressed as a base resistance index by calculating the change in thickness after exposure to the thickness of the flexible circuit board sample measured before exposure to NaOH solution.

That is, the base resistance index calculated through the thickness reduction rate can be viewed as a quantitative value for base resistance.

In the case of a conventional polyimide film, the base resistance index may be approximately 60% or less after passing through the above evaluation method (a). In particular, in the case of an ultra-thin polyimide film having a thickness of 8 µm or less, the evaluation method ( Through a), the base resistance index can be approximately 50% or less.

On the other hand, the polyimide film of the present invention including clay particles and carbon black may have a base resistance index of 60% or more, specifically 65% or more, according to the evaluation method (a), and is improved compared to a conventional polyimide film. It has basic resistance.

On the other hand, the clay particles according to the present invention are clay minerals having a layered structure in which oxide layers having negative charges are stacked, the thickness of the clay particles is about 1 to 100 nm, the length of the long axis is 1 to 10 ㎛, and the aspect ratio is It may be natural clay or synthetic clay particles ranging from about 1 to 1000.

In one specific example, the clay particles are negatively charged phyllosilicates composed of a layer of no-sized aluminum silicate or magnesium silicate, or sodium ions (Na ⁺ ) or potassium ions (K ⁺ ) between phyllosilicate layers. It may be filled potassium or sodium phyllosilicate.

In a more specific example, the phyllosilicate is montmorillonite, hectorite, saponite, beidellite, nontronite, vermiculite, volconscoite ( volkonskoite), soconite, fluorohectorite, magadite, kaolinite, and halloysite may be one or more selected from the group consisting of, but limited to this no.

In addition, clay modified with the phyllosilicate, sodium phyllosilicate, and potassium phyllosilicate with quaternary ammonium ions may be used, and such clay particles have hydrophobic properties, thereby preventing the penetration of a base component into the polyimide film. It can delay or reduce the penetration amount of the basic component, and depending on the structure arranged in the polyimide film, even if inevitable denaturation or decomposition of the polyimide film is caused by a basic solution, etc., it can be useful in suppressing the loss of carbon black. have.

The above will be demonstrated in more detail through'specific details for carrying out the invention', but in summary, it is assumed that the clay particles are present in the polyimide film in at least one state selected from below.

Specifically, in an example, the clay particles may form a plurality of barrier layers in at least one state selected from the following, and at least a portion of carbon black may be positioned between the barrier layers.

(a) a first state in which the long axis of the clay particles is arranged to have an angle of 0 to 45° with the machine direction (MD) of the polyimide film; And

(b) a second state in which the long axis of the clay particles is arranged to have an angle of 0 to 45° with the transverse direction (TD) of the polyimide film.

In a more specific example, the first state may be a structure in which the long axis of the clay particles is arranged parallel to the MD direction of the polyimide film to form a plurality of barrier layers, and in the second state, the long axis of the clay particles is polyimide It may have a structure arranged in parallel with the TD direction of the film to form a plurality of barrier layers.

In another specific example, the clay particles may form a plurality of barrier layers in at least one state selected from the following, and at least a portion of carbon black may be positioned between the barrier layers.

(a) a third state in which clay particles are disposed on the surface of the polyimide film;

(b) a fourth state in which the clay particles are disposed adjacent to the surface of the polyimide film; And

(c) A fifth state arranged inside the polyimide film of clay particles.

As described above, if the polyimide film is slightly decomposed or denatured by the basic solution, the carbon black contained therein may be largely eliminated, and in particular, the basic solution continues to permeate the decomposed or denatured portion from the surface. As a result, the carbon black contained in the polyimide film may be continuously decomposed or denatured.

On the other hand, the polyimide film of the present invention can form a barrier layer including the third state in which the clay particles are disposed on the surface of the polyimide film, and the clay particles having hydrophobicity have a basic solution on the surface of the polyimide film. It can suppress penetration.

In addition, a barrier layer can be formed including the fourth state in which the clay particles are disposed adjacent to the surface of the polyimide film and the fifth state in which the clay particles are disposed inside the polyimide film. Even if the mid film is decomposed or denatured, the carbon black positioned between the plurality of barrier layers formed by the plate-shaped clay particles can be suppressed from falling out of the polyimide film due to their structure.

Therefore, based on the hydrophobicity and structure of the plate-shaped clay particles, it is possible to delay the penetration of the basic solution into the polyimide film, or solve the problem that the carbon black is largely eliminated even if the basic solution penetrates, and the polyimide film It can act effectively in improving the basic resistance of

As such, the polyimide film of the present invention including clay particles together with carbon black may have improved basic resistance based on the clay particles present in the first to fifth states described above.

However, despite the above advantages, it is not desirable to contain a lot of clay particles unconditionally.

Specifically, when the content of the clay particles is at a certain level, the above advantages may be expressed, but if the content exceeds this, the mechanical properties of the polyimide film may be rapidly deteriorated, and the benefits due to the clay particles are not significantly increased. Because.

In some cases, clay particles that are present in excess outside the scope of the present invention may deteriorate mechanical properties, and aggregate with each other to cause structural defects of the polyimide film, for example, pinholes or cracks, and penetration of a base solution, etc. It may be smooth, and in this case, the base resistance may be rather reduced.

In the present invention, it is important to contain an appropriate amount of clay particles so that the mechanical properties of the polyimide film and the foregoing advantages are compatible.

Accordingly, in the present invention, 85 to 94.5% by weight of the polyimide resin, 2 to 5% by weight of clay particles, and 5 to 10% by weight of carbon black may be included based on the total weight of the polyimide film.

The carbon black may have an average particle diameter of 0.1 to 5 µm, and the content of carbon black may be selected to express the desired shielding property in the polyimide film, but excessively added carbon black may have mechanical properties of the polyimide film. It is not preferable because it can be degraded, and there is a possibility that it aggregates with each other to cause surface defects.

In addition, when the content of carbon black is less than the above range, the light transmittance increases, and the polyimide film cannot have a desired level of shielding properties.

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

The diamine monomer is an aromatic diamine, and is classified as follows and examples thereof are given.

1) 1,4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzo As a diamine having one benzene ring in structure, such as an acid acid (or DABA), a diamine having a relatively rigid structure;

2) Diaminodiphenyl ether, such as 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 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- Diamines 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-amino phenoxy) 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. A diamine having 4 phase benzene rings. These can be used alone or in combination of two or more as desired.

The dianhydride monomer 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 Boxylic dianhydride (or DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3, 3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (Or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimelitic Monoester acid anhydride), p-biphenylenebis (trimelitic 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-dicarboxyphenoxy)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, etc. are mentioned. These can be used alone or in combination of two or more as desired.

Manufacturing method of polyimide film

The manufacturing method of the polyimide film of the present invention,

(a) polymerizing a polyamic acid from at least one dianhydride monomer and at least one diamine monomer;

(b) preparing a first composition comprising clay particles and a first organic solvent;

(c) preparing a second composition comprising carbon black and a second organic solvent;

(d) preparing a polyimide precursor composition by mixing the first composition and the second composition with the polyamic acid; And

(e) The polyimide precursor composition may be formed on a support and subjected to heat treatment to be imidized.

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

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

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

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

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

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

The organic solvent is not particularly limited as long as it is a solvent in which 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 Phenolic solvents such as phenol, N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL), and Diglyme, and these may be used alone or in combination of two or more.

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

In one example, the organic solvent that can be particularly preferably used for preparing the polyimide precursor composition of the present invention may be N,N'-dimethylformamide and N,N'-dimethylacetamide, which are amide solvents.

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

The dianhydride monomer may be appropriately selected from the examples described above, and in detail, pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) may further include one or more selected from the group consisting of.

The diamine monomer may be appropriately selected from the examples described above, and in detail, 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2, At least one selected from the group consisting of 6-diaminotoluene and 3,5-diaminobenzoic acid (DABA) may be preferably used.

The polyamic acid prepared as described above may have a weight average molecular weight of 150,000 g/mole or more and 1,000,000 g/mole or less, in detail, 260,000 g/mole or more and 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.

The polyamic acid having such a weight average molecular weight may be preferable for production of a polyimide film having more excellent heat resistance and mechanical properties.

In general, the weight average molecular weight of the polyamic acid may be proportional to the viscosity of the precursor composition containing the polyamic acid and an organic solvent, and the weight average molecular weight of the polyamic acid may be controlled within the above range by adjusting the viscosity.

This is because the viscosity of the precursor composition is proportional to the content of the polyamic acid solid content, in particular, the total amount of the dianhydride monomer and the diamine monomer used in the polymerization reaction.

However, the weight average molecular weight does not show a linear proportional relationship in one dimension to viscosity, and is proportional in the form of a log function.

In other words, even if the viscosity is increased to obtain a polyamic acid having a higher weight average molecular weight, 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 the die in the film forming process of the polyimide film. In this case, it may cause a problem of fairness due to an increase in pressure inside the die.

Accordingly, the polyamic acid of the present invention may include a polyamic acid solid content of 15% by weight to 20% by weight and an organic solvent of 80% to 85% by weight, and in this case, the viscosity is 90,000 cP or more to 300,000 cP or less, in detail It 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 may not cause problems in the film forming process described above.

On the other hand, in the preparation of polyamic acid, a filler may be added for the purpose of improving various properties of the film such as sliding properties, thermal conductivity, conductivity, corona resistance, and loop hardness of the polyimide film derived from the polyamic acid.

The filler to be added is not particularly limited, but preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, dicalcium phosphate, barium sulfate, and calcium carbonate.

The average particle diameter of the filler is not particularly limited, and can be determined according to the characteristics of the polyimide film to be modified and the type of filler to be added.

In one example, the average particle diameter of the filler may be 0.05 µm to 100 µm, specifically 0.1 µm to 75 µm, more preferably 0.1 µm to 50 µm, and particularly 0.1 µm to 25 µm.

If the average particle diameter is less than this range, the modification effect is insignificant, and if it exceeds this range, the filler may greatly impair the surface property of the polyimide film or cause a decrease in the mechanical properties of the film.

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 particle diameter of the filler, or the like.

In one example, the amount of the filler added is 0.01 parts by weight to 100 parts by weight, preferably 0.01 parts by weight to 90 parts by weight, more preferably 0.02 parts by weight to 80 parts by weight, based on 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 difficult to appear, and if it exceeds this range, the mechanical properties of the polyimide film may be greatly reduced. The method of adding the filler is not particularly limited, and it goes without saying that any known method may be used.

The step of preparing the first composition or the second composition may be performed by a milling process.

For the milling, use of a bead milling method may be considered without limitation. Bead milling has an advantage in dispersing clay particles or carbon black because it can be effectively stirred even when the flow rate of the mixture is low.

However, it should be understood that this is only an example to aid in the implementation of the invention.

A non-limiting example of the first organic solvent or the second organic solvent that can be used in the step of preparing the first composition or the second composition is that the clay particles or carbon black can be dispersed, but when mixed, the polyamic acid can be dissolved. It may be a solvent, in detail, the aprotic polar solvent described above.

In some cases, in the step of preparing the first composition or the second composition, a dispersant may be further added, and the dispersant may be 0.5 parts by weight or more and 2 parts by weight or less based on 100 parts by weight of the clay particles or carbon black. It may be added, and the kind thereof is not particularly limited as long as it is soluble in the first organic solvent or the second organic solvent, but a surfactant, a synthetic polymer, or a natural polymer may be used.

In addition, BYK's DISPERBYK ^ㄾ -2155, which can be obtained commercially, may be used.

When the amount of the dispersant is excessive outside the above range, mechanical properties such as corona resistance and heat resistance of the polyimide film may be deteriorated. When it is less than the above range, it is difficult to contribute to the dispersion of carbon black.

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

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

<Thermal imidization method>

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

Drying the precursor composition to form a gel film; And

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

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

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

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

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

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

In some cases, the polyimide film obtained as described above may be further cured by heating and finishing at a temperature of 400° C. to 650° C. for 5 to 400 seconds to further cure the polyimide film. It is also possible to do this under a certain tension to relieve the stress.

<Chemical imidization method>

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

Here, the "dehydrating agent" means a substance that promotes a ring closure reaction through a dehydration action on polyamic acid, and non-limiting examples thereof include an aliphatic acid anhydride, an aromatic acid anhydride, N,N' -Dialkylcarbodiimide, halogenated lower aliphatic, halogenated lower patty acid anhydride, aryl phosphonic dihalides, and thionyl halides.

Among these, aliphatic acid anhydride may be preferred from the viewpoint of availability and cost, and non-limiting examples thereof include acetic anhydride (AA), propion acid anhydride, and lactic acid anhydride. And the like, and these may be used alone or in combination of two or more.

In addition, the term "imidating agent" refers to a substance having an effect of promoting a ring closure reaction with respect to polyamic acid, and is an imine component such as an aliphatic tertiary amine, an aromatic tertiary amine, and a heterocyclic tertiary amine. I can.

Among these, a heterocyclic tertiary amine may be preferable from the viewpoint of reactivity as a catalyst. Non-limiting examples of the heterocyclic tertiary amine include quinoline, isoquinoline, β-picoline (BP), pyridine, and the like, and these may be used alone or in combination of two or more.

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

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

<Complex imidization method>

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

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

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

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

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

The gel film thus obtained is fixed to a tenter and then heat-treated at a variable temperature 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 remaining amic acid groups, the polyimide film of the present invention can be obtained.

Even in such a heat treatment process, a dehydrating agent and/or an imidizing agent may act as a catalyst to rapidly convert an amic acid group into an imide group, thereby enabling a high imidation rate.

In some cases, the polyimide film obtained as described above may be further cured by heating and finishing at a temperature of 400° C. to 650° C. for 5 to 400 seconds to further cure the polyimide film. It is also possible to do this under a certain tension to relieve the stress.

Meanwhile, in the present invention, when applying (discharging) polyamic acid to a support in order to implement an ultra-thin film of 8 μm or less, process conditions such as discharge amount, speed, and pressure must be controlled.

Specifically, it is necessary to minimize the shaking at the point when the polyamic acid solution is discharged from the T-Die to an endless belt and lands in the form of a film.To this end, a general polyimide film is manufactured when the discharge film is formed. Air can be supplied at a pressure lower than the pressure used at the time, for example, 10 to 40 mmH ₂ O.

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

[Equation]

Amount discharged from T-die/Time discharged from T-die = Specific gravity of film*(T-die cross-sectional area)*(Speed of endless belt)

At the laboratory level, an ultra-thin polyimide film can be obtained by controlling the casting thickness, but in a mass production process, when the above range is satisfied, an ultra-thin film of 8 μm or less can be realized.

Specifically, the polyimide film according to the present invention may have a thickness of 7.5 μm or less, specifically, 3 to 7.5 μm, and more specifically, 5 to 7.5 μm.

In addition, in order to prevent breakage in the film during the heat treatment using a device such as a tenter dryer after fixing it to a pin-type frame, the maximum heat treatment temperature standard for manufacturing a yellow polyimide film of the same thickness is 50 to 150. The heat treatment can be performed at a lower temperature.

In addition, the imidization-completed film can be cooled down at 20 to 30°C to form a film.

It has been sufficiently explained above that the polyimide film according to the present invention contains clay particles and carbon black, so that basic resistance can be improved.

In summary, since the polyimide film including clay particles has excellent chemical resistance, it is possible to suppress decomposition and/or modification of the polyimide resin by a base component between carbon black and the polyimide resin based on this.

In addition, the clay particles may delay the penetration of the base component into the polyimide film or reduce the penetration amount of the base component based on its hygroscopicity.

The manufacturing method according to the present invention has a substantial advantage in enabling the implementation of the polyimide film described above.

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

<Example 1>

Preparation Example 1: Polyamic acid polymerization

As a polyamic acid solution polymerization process, 425 g of dimethylformamide (DMF) was added as a solvent in a nitrogen atmosphere to a 500 mL reactor.

After setting the temperature to 25° C., 35.90 g of ODA was added as a diamine monomer, and after confirming that the monomer was dissolved by stirring for about 30 minutes, 39.10 g of PMDA was added as a dianhydride monomer, and finally 280,000 cP at a viscosity of 250,000 cP. The final input amount was adjusted so that it was added.

Upon completion of the addition, the mixture was stirred for 1 hour while maintaining the temperature to polymerize a polyamic acid solution having a final viscosity of 280,000 cP.

Preparation Example 2: Preparation of the first composition

The first composition by mixing 10 g of Chloe site (Cloisite) 30B ^® as clay particles in DMF for 100 g as the first organic solvent was prepared.

Preparation Example 3: Preparation of the second composition

After mixing 10 g of carbon black and 0.1 g of dispersant BYK-430 in 100 g of DMF as a second organic solvent, a second composition including carbon black having an average particle diameter of 0.4 µm was prepared using a milling machine.

Preparation Example 4: Preparation of polyimide film

To 50 g of the polyamic acid solution prepared in Preparation Example 1, 6.55 g of the first composition prepared in Preparation Example 2 and 2.81 g of the second composition prepared in Preparation Example 3 were mixed, and isoquinoline (IQ) 4.76 g as a catalyst, After adding 26.36 g of acetic anhydride (AA) and 18.87 g of DMF, they were uniformly mixed, cast to 70 μm using a doctor blade on a SUS plate (100SA, Sandvik), and dried at a temperature of 100°C to 200°C. .

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

7.5 µm containing 7% by weight of carbon black and 3% by weight of clay particles based on the total weight of the polyimide film after heating the film from 200°C to 600°C in a high-temperature tenter, cooling it at 25°C, and separating it from a pin frame A thick polyimide film was prepared.

<Example 2> to <Example 4>

A polyimide film having a thickness of about 7.5 μm was prepared in the same manner as in Example 1, except that the contents of carbon black and clay particles were changed as shown in Table 1 below.

<Comparative Example 1>

A polyimide film having a thickness of about 7.5 μm was prepared in the same manner as in Example 1, except that clay particles were not added.

<Comparative Example 2> to <Comparative Example 9>

A polyimide film having a thickness of about 7.5 μm was prepared in the same manner as in Example 1, except that the contents of carbon black and clay particles were changed as shown in Table 1 below.

Carbon black
(weight%) Clay particles
(weight%) Example 1 7 3 Example 2 7 5 Example 3 9 3 Example 4 9 5 Comparative Example 1 9 0 Comparative Example 2 9 10 Comparative Example 3 9 One Comparative Example 4 0.5 0.1 Comparative Example 5 One 7 Comparative Example 6 3 9 Comparative Example 7 12 10 Comparative Example 8 15 15 Comparative Example 9 20 20

Experimental Example 1: Base resistance index evaluation

The polyimide films prepared in Examples 1 to 4 and Comparative Examples 1 to 9 were measured for thickness change according to the evaluation method (a) described above, and the results are shown in Table 2 below.

Experimental Example 2: Evaluation of transmittance

For the polyimide films each prepared in Examples 1 to 4 and Comparative Examples 1 to 9, transmittance was measured by ASTM D1003 method in the visible light region using a transmittance measuring device (model name: ColorQuesetXE, manufacturer: HunterLab). And the results are shown in Table 2 below.

<Experimental Example 3: Evaluation of tensile strength>

For the polyimide films each prepared in Examples 1 to 4 and Comparative Examples 1 to 9, tensile strength was measured by the method presented in KS6518, and the results are shown in Table 2 below.

Base resistance index
(%) Transmittance
(%) The tensile strength
(MPa) Example 1 62 0.14 225 Example 2 67 0.11 235 Example 3 63 0.07 230 Example 4 67 0.05 235 Comparative Example 1 54 0.12 210 Comparative Example 2 67 0.01 150 Comparative Example 3 56 0.09 215 Comparative Example 4 59 65.0 220 Comparative Example 5 63 20.0 200 Comparative Example 6 62 7.0 195 Comparative Example 7 56 0.0 160 Comparative Example 8 49 0.0 145 Comparative Example 9 40 0.0 125

Referring to Table 2, it can be seen that the examples including clay particles and carbon black within the scope of the present invention have a base resistance index of 60% or more, and thus the dropout of carbon black by the base solution is relatively small.

That is, it can be seen that the polyimide film of Examples has high basic resistance.

In addition, it can be seen that the transmittance is 0.5% or less and the tensile strength is 225 MPa or more, which satisfies the level of physical properties usable as a polyimide film requiring shielding properties.

On the other hand, in the case of Comparative Example 1 not including the clay particles and Comparative Example 3 including the clay particles less than the scope of the present invention, the base resistance index is not excellent, and in the case of Comparative Example 2 including the clay particles in excess , It can be seen that the tensile strength was measured lower than that of the Example.

In addition, in the case of Comparative Examples 4 to 5 containing less clay particles or carbon black than the range of the present invention, the transmittance was very high, and thus the level was unusable as a polyimide film requiring shielding properties.

On the contrary, in the case of Comparative Examples 6 to 9 containing clay particles or carbon black in excess than the scope of the present invention, it can be seen that the physical properties of any one or more of the base resistance index, transmittance, and tensile strength were significantly reduced.

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

Claims (17)

Based on the total weight of the polyimide film,
85 to 90% by weight of a polyimide resin;
2 to 5% by weight of plate-shaped clay particles; And
5 to 10% by weight of carbon black,
The clay particles are dispersed in the film to form a plurality of barrier layers,
At least some of the carbon black is located between the barrier layers,
A polyimide film having a base resistance index of 60% or more, and a tensile strength of 225 MPa or more, evaluated based on thickness. The method of claim 1,
The clay particles form a plurality of barrier layers in at least one state selected from the following, and at least some of the carbon black is located between the barrier layers, a polyimide film:
(a) a first state in which the long axis of the clay particles is arranged to have an angle of 0 to 45° with the machine direction (MD) of the polyimide film; And
(b) a second state in which the long axis of the clay particles is arranged to have an angle of 0 to 45° with the transverse direction (TD) of the polyimide film. The method of claim 2,
The first state is a state in which the long axis of the clay particles is arranged parallel to the MD direction of the polyimide film to form a plurality of barrier layers, a polyimide film. The method of claim 2,
The second state is a state in which the long axis of the clay particles is arranged in parallel with the TD direction of the polyimide film to form a plurality of barrier layers. The method of claim 1,
The clay particles form a plurality of barrier layers in at least one state selected from the following, and at least some of the carbon black is located between the barrier layers, a polyimide film:
(a) a third state in which clay particles are disposed on the surface of the polyimide film;
(b) a fourth state in which the clay particles are disposed adjacent to the surface of the polyimide film; And
(c) A fifth state in which clay particles are disposed inside the polyimide film. delete The method of claim 1,
The clay particles are at least one selected from the group consisting of phyllosilicates, sodium phyllosilicates, potassium phyllosilicates, and clays treated with quaternary ammonium ions, polyimide film. The method of claim 7,
The phyllosilicate is montmorillonite, hectorite, saponite, beidellite, nontronite, vermiculite, volkonskoite, soconite sauconite), hectorite fluoride (fluorohectorite), magadite (magadite), kaolinite (kaolinite) and one or more selected from the group consisting of haloysite (halloysite), a polyimide film. The method of claim 1,
The polyimide resin is derived from polyamic acid,
The polyamic acid is a polyimide film in which at least one dianhydride monomer and at least one diamine monomer are polymerized. The method of claim 9,
The dianhydride monomer 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'-tetracarboxylic dian Hydride (or DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexa Fluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (or BTDA ), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimellitic monoester acid Anhydride), p-biphenylenebis (trimelitic 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-di Carboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane Dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride and 4,4'-(2,2-hexa) Fluoroisopropylidene) diphthalic acid dianhydride, at least one selected from the group consisting of, polyimide film. The method of claim 9,
The diamine monomer is 1,4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-dia Diaminodiphenyl ethers, such as minobenzoic acid (or DABA), 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 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'-diaminobenz Anilide, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine) and at least one selected from the group consisting of 2,2'-dimethylbenzidine (or m-tolidine), Polyimide film. The method of claim 1,
The carbon black has an average particle diameter of 0.1 to 5 μm, a polyimide film. The method of claim 1,
The polyimide film is a polyimide film having a thickness of 2 to 8 μm. The method of claim 1,
A polyimide film having a light transmittance of 0.5% or less in a visible light region. As a method for producing the polyimide film according to claim 1,
(a) polymerizing a polyamic acid from at least one dianhydride monomer and at least one diamine monomer;
(b) preparing a first composition comprising clay particles and a first organic solvent;
(c) preparing a second composition comprising carbon black and a second organic solvent;
(d) preparing a polyimide precursor composition by mixing the first composition and the second composition with the polyamic acid; And
(e) forming a film of the polyimide precursor composition on a support and imidizing by heat treatment. A coverlay comprising the polyimide film according to claim 1. An electronic device comprising the coverlay according to claim 16.