WO2020017692A1 - Polyimide film comprising clay particles and carbon black and manufacturing method therefor - Google Patents

Abstract

The present invention provides a polyimide film comprising: a polyimide resin; flat-type clay particles; and carbon black, wherein the clay particles are dispersed in a film to form a plurality of barrier layers and at least a portion of carbon black is disposed between the barriers.

Description

Polyimide film comprising clay particles and carbon black and method for producing same

The present invention relates to a polyimide film comprising clay particles and carbon black and a method for producing the same.

Polyimide (PI) is a polymer material having 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 an imide ring.

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

As an example of a microelectronic field, the high integrated circuit etc. which are contained in a portable electronic device and a communication device are mentioned. The polyimide may be used as a film that is attached to or added to a circuit to provide electrical insulation to the circuit and at the same time protects the circuit against moisture, light sources, impacts, and the like.

As a film protecting the circuit as described above, various examples may exist, but in the case of a composite film having an adhesive layer formed on one or both sides of the film, the film may be referred to as a coverlay in a narrow sense, and the polyimide film may be 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 is spotlighted as a material of a coverlay.

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

At this time, when the polyimide film is slightly decomposed or modified by the basic solution, the carbon black contained therein may be largely dropped.

For this reason, the shielding may be lost along with the removal of the black tint from the coverlay, and the weight and thickness reduction may be accompanied as well as the surface due to the dropping of the carbon black, so that the function as the coverlay may be significantly degraded.

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

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

According to one aspect of the invention, the polyimide film is produced to include clay particles and carbon black.

In this aspect, the clay particles included in the polyimide film of the present invention may act usefully to suppress the dropping of carbon black, even if undesired modification or decomposition of the polyimide film is caused by a basic solution or the like.

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

As a result, the above conventional problem can be solved according to one aspect of the present invention.

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

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

Plate-shaped clay particles; And

Contains carbon black,

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

It provides a polyimide film, wherein at least some carbon black is located between the barrier layers.

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 comprising the coverlay.

Hereinafter, embodiments of the 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, terms or words used in the present specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that it can be defined.

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 idea of the present invention, various equivalents and modifications that can replace them at the time of the present application It should be understood that examples may exist.

As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly indicates otherwise. As used herein, the terms "comprise", "comprise" or "have" are intended to indicate that there is a feature, number, step, component, or combination thereof, that is, one or more other features, It is to be understood that the present invention does not exclude the possibility of adding or presenting numbers, steps, components, or combinations thereof.

As used herein, "dianhydride" is intended to include precursors or derivatives thereof, which technically may not be dianhydride, but nevertheless will react with the diamine to form a polyamic acid. This polyamic acid can be converted back to polyimide.

As used herein, "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but will nevertheless react with dianhydrides to form polyamic acid, which polyamic The acid can be converted back to polyimide.

Where an amount, concentration, or other value or parameter is given herein as an enumeration of ranges, preferred ranges, or preferred upper and preferred lower values, any pair of upper range limits, whether or not the ranges are disclosed separately, or It is to be understood that this disclosure specifically discloses all ranges that may be formed to the desired value and any lower range limit or desired value. When a range of numerical values is mentioned herein, unless stated otherwise, the range is intended to include the endpoint and all integers and fractions within that range. It is intended that the scope of the invention not be limited to the particular values mentioned when defining the range.

Polyimide film

Polyimide resins;

Plate-shaped clay particles; And

Contains carbon black,

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

At least some 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 unavoidable denaturation by the basic solution, and also preventing the drop of carbon black.

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

In addition, the polyimide film containing carbon black is not only difficult to manufacture but also more vulnerable to the base component due to the dropping of carbon black as described above.

Dropping out of carbon black can also cause light transmittance degradation in polyimide films comprising it.

Accordingly, there is a need for improved 'base resistance' of polyimide films, especially polyimide films comprising carbon black.

The basic resistance means that the polyimide film is not easily decomposed and / or denatured even when exposed to the base environment, and the thickness of the polyimide film is reduced during the decomposition and / or denaturation. You can judge.

One example for evaluating base resistance in this regard is a method of exposing a polyimide film to a basic solution and measuring the change in thickness of the film before and after exposure.

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

Evaluation method (a) may comprise the following steps:

Corona treating both sides of the polyimide film;

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

Measuring the thickness of the sample of the flexible circuit board, and then exposing the same sample to 10% NaOH solution at 50 ° C. for 100 minutes to measure the thickness.

The thickness reduction rate by the evaluation method (a) can be expressed as a base resistance index by calculating the percentage change in thickness after exposure to the thickness of the flexible circuit board sample measured before exposure to NaOH solution.

In other words, it can be seen as a quantitative value for the base resistance by the base resistance index calculated through the thickness reduction rate.

In the case of a conventional polyimide film, the base resistance index may be about 60% or less after 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 ( After a), the base resistance index may be about 50% or less.

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

Meanwhile, 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 clay particles have a thickness of about 1 to 100 nm, a long axis of 1 to 10 μm, and an aspect ratio. Natural clay or synthetic clay particles in the range of about 1 to 1000.

In one specific example, the clay particles are negatively charged phyllosilicates consisting of knocked aluminum silicate or magnesium silicate layers, or sodium ions (Na ⁺ ) or potassium ions (K ⁺ ) between the phyllosilicate layers. It may be potassium or sodium phyllosilicate filled.

In a more specific example, the phyllosilicate is montmorillonite, hectorite, saponite, beadelite, nontronite, vermiculite, bolconscote ( It may be at least one selected from the group consisting of volkonskoite, sauconite, fluorohectorite, fluorohectorite, magadite, kaolinite, and halloysite, but is not limited thereto. no.

In addition, clays in which the phyllosilicate, sodium phyllosilicate, and potassium phyllosilicate are modified with tetravalent ammonium ions may be used, and the clay particles have hydrophobicity, thereby preventing the base component from penetrating into the polyimide film. It is possible to delay or reduce the amount of penetration of the base component, and depending on the structure disposed in the polyimide film, even if inevitable modification or degradation of the polyimide film is caused by the basic solution or the like, it may be useful to suppress the dropping of carbon black. have.

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

Specifically, in the example, the clay particles may form a plurality of barrier layers in at least one state selected from below, and at least some carbon black may be located between the barrier layers.

(a) a first state in which the long axis of the clay particles is disposed at 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 have a structure in which the long axis of the clay particles is disposed in parallel with 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 The structure may be disposed parallel to 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 below, and at least some carbon black may be located between the barrier layers.

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

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

(c) 5th state arrange | positioned inside the polyimide film of a clay particle.

As described above, when 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 penetrate the decomposed or denatured portion from the surface. As a result, the carbon black contained in the polyimide film may be continuously dropped.

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

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

Therefore, based on the hydrophobicity and the structure of the plate-shaped clay particles, the problem of delaying the penetration of the basic solution into the polyimide film, or eliminating the large drop of carbon black even if the basic solution is penetrated, can be solved. It can act effectively to improve the base resistance of the.

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

Despite the above advantages, however, it is not preferable to contain a large amount of clay particles unconditionally.

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

In some cases, the clay particles present in an excess beyond the scope of the present invention may degrade mechanical properties, and aggregate with each other to cause structural defects of the polyimide film, for example, pinholes or cracks, to penetrate the base solution. In this case, the base resistance may be rather reduced.

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

Thus, in the present invention, the total weight of the polyimide film may include 85 to 94.5 wt% of polyimide resin, 2 to 5 wt% of clay particles, and 5 to 10 wt% of carbon black.

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

In addition, when the content of carbon black is less than the above range, the light transmittance is increased so that the polyimide film may not have a desired level of shielding property.

On the other hand, the polyimide resin of the present invention may be derived from a polyamic acid. The polyamic acid may be a polymerized dianhydride monomer and a diamine monomer.

The said diamine monomer is an aromatic diamine, classified as follows, and an example is given.

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 structure, such as Ik acid (or DABA) and the like, include diamines having a relatively rigid structure;

2) diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 3,4'-diaminodiphenyl ether, and 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'-diaminodiphenylether, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 3,3'-diaminodiphenylsulfide, 3,4 ' -Diaminodiphenylsulfide, 4,4'-diami Diphenylsulfide, 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'-diaminodi Phenylmethane, 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'-diaminodiphenylsulfoxide, 4,4'-diaminodiphenylsulfoxide Diamines having two benzene rings in structure, such as Said and the like;

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- Having three benzene rings in structure, such as bis [2- (4-aminophenyl) isopropyl] benzene Diamine;

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 Phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-amino phenoxy) phenyl] ketone, bis [3- (3-amino phenoxy) 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-ami) Phenoxy) 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, Like 3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, and the like, Diamines having four benzene rings in structure. These can be used individually or in combination of 2 or more types 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 Cyclic 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 An Idride), 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-dicarboxy Phenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) biphenyl dianhydride, 2,2-bis [(3,4-dicarboxy phenoxy) phenyl] propane dian Hydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4 '-(2,2-hexafluoro And low isopropylidene) diphthalic acid dianhydride. These can be used individually or in combination of 2 or more types as desired.

Manufacturing method of polyimide film

The manufacturing method of the polyimide film of this 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) mixing the first composition and the second composition with the polyamic acid to prepare a polyimide precursor composition; And

(e) forming a polyimide precursor composition on a support and performing heat treatment to imidize the polyimide precursor composition.

The preparation of the polyamic acid solution in the invention is, for example,

(1) a method in which the entire amount of the diamine monomer is placed in a solvent, and then the dianhydride monomer is added to be substantially equimolar with the diamine monomer and polymerized;

(2) a method in which the entire amount of the dianhydride monomer is placed in a solvent, and then the diamine monomer is added to be substantially equimolar with the dianhydride monomer and polymerized;

(3) After putting some components of the diamine monomer in the solvent, and mixing some components of the dianhydride monomer in the ratio of about 95 to 105 mol% with respect to the reaction component, the remaining diamine monomer component is added and the rest Adding a dianhydride monomer component so that the diamine monomer and the dianhydride monomer are substantially equimolar and polymerized;

(4) After putting the dianhydride monomer in a solvent, after mixing some components of a diamine compound in the ratio of 95-105 mol% with respect to a reaction component, another dianhydride monomer component is added and it continues, and the remaining diamine monomer component is carried out. Adding a diamine monomer and a dianhydride monomer to substantially equimolar polymerization;

(5) Some of the diamine monomer component and some of the dianhydride monomer component are reacted to an excess in one solvent to form a first composition, and some of the diamine monomer component and some dianhydride monomer component in another solvent are either Reacting with excess to form a second composition, and then mixing the first and second compositions and completing the polymerization, wherein the second composition is excessive when the diamine monomer component is excessive when the first composition is formed. In the case where the dianhydride monomer component is in excess and the dianhydride monomer component in the first composition is in excess, in the second composition, the diamine monomer component is in excess, and the first and second compositions are mixed and used for these reactions. The total diamine monomer component and the dianhydride monomer component to be substantially equimolar It can be joined to the methods.

The organic solvent is not particularly limited as long as the solvent can dissolve the polyamic acid, but as an example, the organic solvent may be an aprotic polar solvent.

Non-limiting examples of the aprotic polar solvent include amide solvents such as N, N'-dimethylformamide (DMF) and N, N'-dimethylacetamide (DMAc), p-chlorophenol, o-chloro Phenol solvents such as phenol, N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL), diglyme, and the like, and the like, and these may be used alone or in combination of two or more thereof.

In some cases, the solubility of the polyamic acid may be adjusted by using auxiliary solvents such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol and water.

In one example, the organic solvents that may 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.

The polymerization method is not limited only to the above examples, and any known method may be used.

The dianhydride monomer may be appropriately selected from the examples described above, and specifically, 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, 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) can 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. Or more and 500,000 g / mole or less.

The polyamic acid having such a weight average molecular weight may be preferable for the 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 including the polyamic acid and the organic solvent, so that the weight average molecular weight of the polyamic acid may be controlled in 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 solids, specifically the total amount of dianhydride monomers and diamine monomers used in the polymerization reaction.

However, the weight average molecular weight does not represent a linear proportional relationship with respect to the viscosity, but is proportional in the form of a logarithmic function.

That is, even if the viscosity is increased to obtain a higher weight average molecular weight polyamic acid, the range in which the weight average molecular weight can be increased is limited, but when the viscosity is too high, the precursor composition is discharged through the die in the film forming process of the polyimide film. At the same time, it may cause a problem of fairness due to pressure rise inside the die.

Thus, the polyamic acid of the present invention may include 15% to 20% by weight of polyamic acid solids and 80% to 85% by weight of an organic solvent, in which case the viscosity is 90,000 cP or more and 300,000 cP or less, in detail. May be at least 100,000 cP 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, a filler may be added in the production of the polyamic acid for the purpose of improving various properties of the film such as the slidability, thermal conductivity, conductivity, corona resistance, and loop hardness of the polyimide film derived from the polyamic acid.

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

The average particle diameter of a filler is not specifically limited, It can determine according to the polyimide film characteristic to modify and the kind of filler to add.

In one example, the average particle diameter of the filler may be from 0.05 μm to 100 μm, in particular from 0.1 μm to 75 μm, more preferably from 0.1 μm to 50 μm, in particular from 0.1 μm to 25 μm.

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

In addition, it is not specifically limited also about the addition amount of a filler, It can determine by the polyimide film characteristic to be modified, filler particle diameter, etc ..

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

If the amount of filler added is less than this range, the effect of modification by the filler is less likely to appear, and if it exceeds this range, the mechanical properties of the polyimide film may be greatly reduced. The addition method of a filler is not specifically limited, Of course, any well-known method can be used.

Preparing the first composition or the second composition may be performed by a milling process.

The milling can be considered using, but not limited to, bead milling methods. Bead milling can be effectively stirred even when the flow rate of the mixture is low, which is advantageous in the dispersion of clay particles or carbon black.

It should be understood that this is only an example to assist in the practice of the invention.

Non-limiting examples of the first organic solvent or the second organic solvent that can be used in the preparation of the first composition or the second composition, are capable of dissolving the polyamic acid when capable of dispersing the clay particles or carbon black while being mixed. Solvent, specifically the aprotic polar solvent described above.

In some cases, a dispersant may be further added in the preparation of the first composition or the second composition, 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. Although it can add, the kind is not specifically limited as long as it is soluble in a 1st organic solvent or a 2nd organic solvent, Surfactant, a synthetic polymer, or a natural polymer can be used.

It is also possible to use commercially available ^BYPER 's DISPERBYK®- ²¹⁵⁵ .

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

Meanwhile, the imidization of the step of obtaining the polyimide film may include casting the precursor composition on a support and drying to prepare a gel film, and then imidating the gel film to form a polyimide film. have.

As a specific method of such imidation, the thermal imidation method, the chemical imidation method, or the composite imidation method which uses the said thermal imidation method and the chemical imidation method together is mentioned as an example, About these the following non-limiting examples It will be described in more detail through.

<Thermal imidization method>

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

Drying the precursor composition to form a gel film; And

The gel film may be heat-treated to obtain a polyimide film.

Here, a gel film can be understood as a film intermediate which has self-support at an intermediate stage with respect to the conversion from polyamic acid to polyimide.

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

This may result in the formation of a gel film by partial curing and / or drying of the precursor composition. It can then peel off from the support to obtain a gel film.

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 orientation, and the stretching may be performed in the machine transport direction (MD) and the machine transport direction. It may be performed in at least one direction of the transverse direction (TD) with respect to.

The gel film thus obtained is fixed in 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 solvents, and the like remaining in the gel film. Nearly all amic acid groups can be imidated to obtain the polyimide film of the present invention.

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 cure the polyimide film, and may remain in the obtained polyimide film. This may be done under a predetermined tension to relieve 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.

As used herein, the term "dehydrating agent" refers to a substance that promotes a ring-closure reaction through dehydration to polyamic acid, and includes, but is not limited to, aliphatic acid anhydrides, aromatic acid anhydrides, and N, N '. -Dialkylcarbodiimide, halogenated lower aliphatic, halogenated lower patty acid anhydride, aryl phosphonic dihalide, thionyl halide and the like.

Of these, aliphatic acid anhydrides may be preferred in view of ease of availability and cost, and non-limiting examples thereof include acetic anhydride (AA), propion acid anhydride, and lactic acid anhydride. These etc. are mentioned, These can be used individually or in mixture of 2 or more types.

In addition, "imidizing agent" means a substance having an effect of promoting a ring closure reaction to polyamic acid, and may be an imine-based component such as aliphatic tertiary amine, aromatic tertiary amine, and heterocyclic tertiary amine. Can be.

Of these, heterocyclic tertiary amines may be preferable in view of reactivity as a catalyst. Non-limiting examples of heterocyclic tertiary amines include quinoline, isoquinoline, β-picolin (BP), pyridine, and the like, and these may be used alone or in combination of two or more thereof.

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

When the dehydrating agent and the imidating agent are less than the above range, chemical imidization is insufficient, cracks may be formed in the polyimide film to be produced, and the mechanical strength of the film may be lowered. In addition, if the amount of these additions exceeds the above range, the 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.

<Complex imidation method>

In connection with the above-mentioned chemical imidation method, the composite imidation method which further performs the thermal imidation method can be used for manufacture of a polyimide film.

Specifically, the complex imidization method includes a chemical imidization method of adding a dehydrating agent and / or an imidizing agent to the 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.

In performing the chemical imidization process, the type and amount of the dehydrating agent and the imidizing agent may be appropriately selected according to the above-described chemical imidization method.

In the process of forming the gel film, the precursor composition containing the dehydrating agent and / or the 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 onto the support. The precursor composition is dried at a variable temperature in the range of 50 ° C. to 180 ° C., specifically 80 ° C. to 180 ° C. In this process, chemical converting agents and / or imidating agents can act as catalysts so that amic acid groups can be rapidly converted 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 orientation, and the stretching may be performed in the machine transport direction (MD) and the machine transport direction. It may be performed in at least one direction of the transverse direction (TD) with respect to.

The gel film thus obtained is fixed in 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, Nearly all remaining amic acid groups can be imidated to obtain the polyimide film of the present invention.

In such a heat treatment process, the dehydrating agent and / or the imidating agent may act as a catalyst so that the amic acid group may be rapidly converted into the imide group, thereby enabling 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 cure the polyimide film, and may remain in the obtained polyimide film. This may be done under a predetermined tension to relieve stress.

Meanwhile, in the present invention, when the polyamic acid is applied (discharged) to the support to realize an ultra-thin film of 8 μm or less, process conditions such as discharge amount, speed, and pressure should be controlled.

Specifically, the shake at the point of time when the polyamic acid solution is discharged from the T-die to the endless belt and landed in the form of a film should be minimized. It is possible to supply air at a pressure lower than the pressure used at the time, for example, a pressure of 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, the speed of the endless belt It may be from 15 mpm to 25 mpm.

[Equation]

Quantity 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, the casting thickness may be adjusted to obtain an ultra-thin polyimide film. However, in the mass production process, when the above range is satisfied, an ultra-thin film of 8 μm or less may 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, more specifically 5 to 7.5 μm.

In addition, in order to prevent breakage in the film during the heat treatment process when the heat treatment using a device such as a tenter dryer after fixing to the pin-type frame, 50 to 150 of the heat treatment maximum temperature standard in the manufacture of the same thickness yellow polyimide film Heat treatment can be carried out at low temperatures.

In addition, the film in which imidation is completed can be cooled and film-formed at 20-30 degreeC.

Hereinafter, the operation and effects of the invention will be described in more detail with reference to specific examples of the invention. However, these embodiments are only presented as an example of the invention, whereby the scope of the invention is not determined.

<Example 1>

Preparation Example 1 Polyamic Acid Polymerization

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

After the temperature was set at 25 ° C., 35.90 g of ODA was added as a diamine monomer and stirred for about 30 minutes to confirm that the monomer was dissolved. Then, 39.10 g of PMDA was added as a dianhydride monomer and finally 280,000 cP at a viscosity of 250,000 cP The last dose was adjusted to be added.

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

Preparation Example 2 Preparation of First Composition

A first composition was prepared by mixing 100 g of DMF as a first organic solvent and 10 g of Cloisite 30B ^® as clay particles.

Preparation Example 3 Preparation of Second Composition

As a second organic solvent, 10 g of carbon black and 0.1 g of dispersant BYK-430 were mixed with 100 g of DMF, and 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

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

The film was heated from 200 ° C. to 600 ° C. in a high temperature tenter and then cooled at 25 ° C. and separated from the fin frame to 7.5 μm containing 7 wt% carbon black and 3 wt% clay particles relative to the total weight of the polyimide film. A polyimide film of thickness 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 content of the carbon black and the clay particles was changed as in Table 1 below.

Comparative Example 1

A polyimide film about 7.5 μm thick was prepared in the same manner as in Example 1, except that no clay particles were 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 content of the carbon black and the clay particles was changed as in Table 1 below.

	Carbon black (% by weight)	Clay particles (% by 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: Evaluation of Base Resistance Index

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

Experimental Example 2: Evaluation of Permeability

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

Experimental Example 3 Evaluation of Tensile Strength

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

	Base Resistance Index (%)	Permeability (%)	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, the examples including the clay particles and carbon black as the scope of the present invention can be seen that the base resistance index of 60% or more, the removal of carbon black by the base solution is relatively low.

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

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

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

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

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

Although described above with reference to embodiments of the present invention, those of ordinary skill in the art, it will be possible to perform various applications and modifications within the scope of the present invention based on the above contents.

The polyimide film according to the present invention has been fully described above by including clay particles and carbon black, whereby the base resistance can be improved.

In summary, since the polyimide film containing clay particles is excellent in chemical resistance, 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 based on this.

In addition, the clay particles may delay the phenomenon of the base component penetrating 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 a substantial advantage in enabling the implementation of the polyimide film described above.

Claims (17)

1. Polyimide resins;

   Plate-shaped clay particles; And

   Contains carbon black,

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

   At least some carbon black is located between the barrier layers.
2. The method of claim 1,

   Wherein said clay particles form a plurality of barrier layers in at least one state selected from below, wherein at least some carbon black is located between the barrier layers:

   (a) a first state in which the long axis of the clay particles is disposed at 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.
3. The method of claim 2,

   Said 1st state is a state in which the long axis of a clay particle is arrange | positioned in parallel with MD direction of a polyimide film, and forms a some barrier layer.
4. The method of claim 2,

   Said 2nd state is a state in which the long axis of a clay particle is arrange | positioned in parallel with the TD direction of a polyimide film, and forms a some barrier layer.
5. The method of claim 1,

   Wherein said clay particles form a plurality of barrier layers in at least one state selected from below, wherein at least some carbon black is located between the barrier layers:

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

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

   (c) 5th state in which clay particle is arrange | positioned inside a polyimide film.
6. The method of claim 1,

   85 to 94.5 weight percent of polyimide resin, relative to the total weight of polyimide film,

   2 to 5 weight percent clay particles, and

   5 to 10 weight percent carbon black.
7. The method of claim 1,

   The clay particles are one or more selected from the group consisting of phyllosilicates, sodium phyllosilicates, potassium phyllosilicates and clays treated with tetravalent ammonium ions.
8. The method of claim 7, wherein

   The phyllosilicate may be montmorillonite, hectorite, saponite, beadelite, nontronite, vermiculite, volkonskoite, soconite A polyimide film, which is at least one selected from the group consisting of sauconite, fluorohectorite, magadite, kaolinite, and halloysite.
9. The method of claim 1,

   The polyimide resin is derived from a polyamic acid,

   The polyamic acid is a polyimide film, wherein at least one dianhydride monomer and at least one diamine monomer are polymerized.
10. 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 (trimelitic monoester acid) Anhydride), p- Diphenylenebis (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 Lide, 1,4-bis (3,4-dicarboxyphenoxy) biphenyl dianhydride, 2,2-bis [(3,4-dicarboxy phenoxy) phenyl] propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride and 4,4 '-(2,2-hexafluoroisopropylidene) di Polyimide film, which is at least one member selected from the group consisting of phthalic acid dianhydride.
11. 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 1 selected from the group consisting of anilide, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine) and 2,2'-dimethylbenzidine (or m-tolidine) Polyimide film which is a species or more.
12. The method of claim 1,

    The carbon black has an average particle diameter of 0.1 to 5 ㎛ polyimide film.
13. The method of claim 1,

    The polyimide film has a thickness of 2 to 8 ㎛ polyimide film.
14. The method of claim 1,

    Polyimide film which satisfy | fills all the following conditions:

    (a) the base resistance index, based on thickness, is at least 60%,

    (b) the light transmittance in the visible range is 0.5% or less;

    (c) The tensile strength is at least 225 MPa.
15. As a method of manufacturing 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) mixing the first composition and the second composition with the polyamic acid to prepare a polyimide precursor composition; And

    (e) forming a polyimide precursor composition on a support and performing heat treatment to imidize the polyimide precursor composition.
16. A coverlay comprising the polyimide film of claim 1.
17. An electronic device comprising the coverlay of claim 16.