KR20200022146A - Polyimide Film with Improved Base Resistance and Method for Preparing The Same - Google Patents

Abstract

Provided is a polyimide film which is prepared by imidizing a precursor composition composed of: a first polyamic acid in which a first diamine having two or less of benzene rings and a first dianhydride are polymerized; a second polyamic acid in which a second diamine having three or more benzene rings and a second dianhydride are polymerized; and carbon black. The crystallinity is 65% or higher, the light transmittance is 0.09 or less, a basic resistance index evaluated based on the thickness of the polyimide film before and after exposure to base components is 70% or higher, and the thickness is 8.0 μm or less.

Description

Polyimide Film with Improved Base Resistance and Method for Preparing The Same}

The present invention relates to a polyimide film having improved base resistance and a method of manufacturing 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.

In order to produce a polyimide film having a black tint, a process of mixing and evenly dispersing carbon black in a polyamic acid as a precursor is essential. If the carbon black is not evenly dispersed in this process, problems such as poor shielding or surface defects may occur. In essence, carbon blacks differ in physical / chemical properties from polyamic acids or polyimides and are therefore not easily blended and / or dispersed in polyimides or polyamic acids.

In addition, 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 with the removal of the black tint from the coverlay, and the weight and thickness reduction may be accompanied as well as the surface defects due to the dropping of the carbon black, so that the function as the coverlay may be significantly reduced.

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

According to an aspect of the present invention, a polyimide film prepared using the first polyamic acid, the second polyamic acid, and carbon black having different characteristics from each other, even though it is in the form of an ultra thin film of 8 μm or less, While meeting the mechanical properties, it may have very good shielding properties and resistance to improved base components (hereinafter referred to as 'base resistance').

According to another aspect of the present invention, when preparing a mixed solution containing the second polyamic acid and carbon black and mixed with the first polyamic acid to produce a polyimide film, the dispersion of the carbon black is improved to improve the quality of the polyimide A film can be obtained.

According to these aspects, the prior art problem can be solved, and thus the present invention has a substantial object to provide a specific embodiment thereof.

In one embodiment, the present invention provides a polymer comprising: a first polyamic acid polymerized with a first diamine containing a first dianhydride and up to two benzene rings;

A second polyamic acid polymerized with a second diamine containing a second dianhydride and three or more benzene rings; And it provides a polyimide film prepared by imidating a precursor composition comprising carbon black.

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 film according to the present invention,

A first polyamic acid polymerized with a first diamine containing a first dianhydride and up to two benzene rings;

A second polyamic acid polymerized with a second diamine containing a second dianhydride and three or more benzene rings; And

Prepared by imidizing a precursor composition comprising carbon black,

The crystallinity is 65% or more, the light transmittance is 0.09 or less, the base resistance index evaluated based on the polyimide film thickness before and after the base component exposure is 70% or more, the thickness may be 8.0 ㎛ or less.

In one specific example, the first polyamic acid may form a first polyimide chain through imidization, and the second polyamic acid may form a second polyimide chain through imidization.

In some aspects, at least a portion of the first polyimide chain and the second polyimide chain may be crosslinked with each other through imidization.

The first polyamic acid may be a material having a relatively rigid structure in molecular structure. Thus, the first polyimide chain derived from the first polyamic acid can be of relatively rigid structure.

This first polyimide chain can contribute to inherent the tensile strength and / or modulus inevitably required for the polyimide film, in particular for the polyimide film to have a certain mechanical strength.

The second polyamic acid may be a material having a relatively flexible structure on the molecular structure, a material having a relatively high crystallinity and excellent chemical resistance. Accordingly, the second polyimide chain derived from the second polyamic acid may be relatively high in crystallinity and excellent in chemical resistance.

Note that, as the properties of each of these chains work complementarily, the polyimide film of the present invention not only inherently possesses a level of mechanical properties corresponding to the first polyimide chain, even in a thin form of 8 μm or less. The predetermined degree of crystallinity (65% or more) and chemical resistance, which are difficult to be embedded by only one polyimide chain, may be embedded by the second polyimide chain.

In general, since the polymer crystals scatter or absorb light, the higher the crystallinity, the lower the light transmittance of the film. In contrast, the polyimide film of the present invention is a conventional polyimide film having a low crystallinity of less than 65%. It can have a relatively low light transmittance in comparison. This can serve as a very important advantage in polyimide films containing carbon black where shielding, shading and the like are required.

Based on the foregoing features, the polyimide film of the present invention may have the following physical properties.

The crystallinity of the polymer in the film state is 70% or more,

Tensile strength is more than 200 kgf / cm ³ ,

Modulus is 3 GPa or more,

Light transmittance is 0.07 or less,

The base resistance index evaluated based on the polyimide film thickness before and after base component exposure may be at least 75%.

In one specific example, the first polyamic acid has a viscosity of 50,000 cP to 300,000 cP measured at 23 ° C. when the solid content is 15% by weight, and the second polyamic acid has 23 ° C. when the solid content is 15% by weight. The viscosity measured at may be 5,000 cP to 30,000 cP.

When the viscosity of the first polyamic acid is less than 50,000 cP, the polyimide film may significantly reduce heat resistance and mechanical properties. When the viscosity of the first polyamic acid is more than 300,000 cP, there may be a problem in terms of the manufacturing process of the film. Specifically, as the precursor composition has high viscosity, there may be a problem in the film forming process of the film, and it may be difficult to produce the film to 8 μm or less.

When the viscosity of the second polyamic acid is less than 5,000 cP, the formation of the second polyimide chain may not be sufficient. This is not preferable in terms of improving the base resistance of the polyimide film. When the viscosity of the second polyamic acid exceeds 30,000 cP, the dispersibility of carbon black in the precursor composition may be lowered, which is not preferable in view of manufacturing processability of the polyimide film.

On the other hand, polyimide is vulnerable to base components such as degradation or denaturation when exposed to a base environment. In the polyimide film containing carbon black, when the decomposition or modification by the base component, the carbon black is largely eliminated and the thickness reduction is more serious.

In recent years, in order to cope with the miniaturization of electronic devices, ultra-thin polyimide films of very thin thickness, for example, 8 µm or less have been required. However, the dropout phenomenon of carbon black in the ultra-thin polyimide film is more severe than that of the polyimide film having a typical thickness of 10 μm or more. This is because even if the same absolute amount of carbon black is dropped in the normal polyimide film and the ultra-thin polyimide film, the ratio of the carbon black dropped to the carbon black of the entire polyimide film is much higher in the ultra-thin type. In addition, since the base component penetrates from the surface, in the case of an ultra-thin polyimide film having a close distance to the surface, relatively more carbon black may be eliminated under the same conditions.

Therefore, ultrathin polyimide films having a thickness of 8 µm or less, particularly including carbon black, need to improve their 'base resistance'.

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 the basic resistance in this regard is a method of exposing a polyimide film to a basic solution and measuring the thickness change of the film before and after exposure, and in the present invention a test method (a) comprising the following steps: Uses:

Corona treating both sides of the polyimide film;

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

The flexible circuit board cut to 4 * 10 ㎝ was exposed to 10% NaOH solution for 3 minutes at 55 ° C, and the desmear solution (10% NaMnO ₄ + 4% NaOH) was exposed to 5 minutes at 55 ° C. Repeating twice and measuring the thickness of the film (second thickness); And

Indicating the degree of change of the second thickness relative to the first thickness as a percentage ((first thickness-second thickness) / first thickness X 100).

In the case of the conventional polyimide film, after the above test method (a), the basic resistance index may be about 50% to 60%.

On the other hand, the polyimide film of the present invention may have a base resistance index according to the test method (a) of at least 70% or more, in particular 75% or more, in particular 80% or more. This is a markedly improved base resistance compared to conventional polyimide films.

The above will be demonstrated in more detail through 'specifications for carrying out the invention', but in summary, as the second polyimide chain derived from the second polyamic acid has relatively strong resistance to the base component, It is assumed that not only the base component penetration into the mid film is blocked, but also the second polyimide chain can maintain the skeleton of the polyimide film to some extent even if the first polyimide chain is decomposed. Accordingly, of course, the frequency of the carbon black dropout phenomenon can be significantly reduced.

Despite the above advantages, however, it is not preferable that the second polyimide chain is unconditionally contained in the polyimide film unconditionally.

Specifically, the above advantages may be expressed when the content of the second polyimide chain in the polyimide film is at a certain level, but if it exceeds, the benefits for the base resistance are not enhanced or improved, whereas the tensile strength of the polyimide film And / or the modulus may drop dramatically.

This phenomenon may be more prominent in ultra thin films of 8.0 μm or less. That is, it is important that the polyimide film contains an appropriate amount of the first polyimide chain and the second polyimide chain so that the mechanical properties and the base resistance are compatible.

Thus, the polyimide film of the present invention has an average particle diameter of 80 to 92% by weight of the first polyimide chain, 3 to 10% by weight of the second polyimide chain, and 5 to 10% by weight, based on the total weight thereof. 5 μm of carbon black, and the thickness of the film may be 7.5 μm or less.

More specifically, the polyimide film of the present invention may include from 5 to 7 wt% of the second polyimide chain of 83 to 92 wt% of the first polyimide chain, based on its total weight.

In one specific example, the first dianhydride is pyromellitic dianhydride (or PMDA),

The second dianhydride is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (or s-BPDA) and / or 2,3,3', 4'-biphenyltetracarboxylic Ric dianhydride (or a-BPDA).

The first diamine,

1) Diamines with one benzene ring: 1,4-diaminobenzene (or paraphenylenediamine, PDA, PPD), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-dia Minotoluene, 3,5-diaminobenzoic acid (DABA);

2) diamines having two benzene rings: 4,4'-diaminodiphenylether (or oxydianiline, ODA), 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylmethe Phosphorus (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoro) Methyl) -4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane Phosphorus, 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'-dimeth Oxybenzidine, 3,3'-diaminodiphenylether, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 3,3'-diaminodiphenylsulfide, 3,4 '-Diaminodiphenylsulfide, 4,4'-dia Nodiphenylsulfide, 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 and 4,4'-diaminodiphenylsulfoxide It may be at least one selected from the group consisting of side.

The second diamine may be 1,3-bis (4-aminophenoxy) benzene (TPE-R) and / or 1,4-bis (3-aminophenoxy) benzene (TPE-Q).

The first diamine and the first dianhydride have a rigid molecular structure, and the second polyimide chain formed by combining them may realize a predetermined level of heat resistance, tensile strength and modulus required for the polyimide film.

The TPE-based diamine is a monomer containing three benzene rings, a monomer having excellent chemical resistance, and may mainly act to increase the crystallinity of the polymer.

The BPDA-based dianhydride is a relatively soft monomer on the molecular structure including two benzene rings, and excellent in chemical resistance.

Thus, the second polyimide chains formed by combining them can implement excellent chemical resistance.

Manufacturing method of polyimide film

The manufacturing method of the polyimide film of this invention,

Polymerizing a first polyamic acid from the first dianhydride and the first diamine;

Polymerizing a second polyamic acid from a second dianhydride and a second diamine;

Preparing a carbon black liquid having an average particle diameter of 0.1 to 5 μm using a milling machine and preparing a black crude liquid comprising the same;

Preparing a mixed liquid by mixing the second polyamic acid and the black crude liquid;

Preparing a precursor composition by mixing the mixed solution with the first polyamic acid; And

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

In general, carbon blacks tend to agglomerate rather than readily disperse upon simple mixing with polyamic acid. On the other hand, the first polyamic acid and the second polyamic acid, which share similar chemical properties, can be relatively easily mixed.

Thus, in the production method of the present invention, the carbon black in the form of the black crude liquid is mixed with the second polyamic acid having a relatively low viscosity, thereby easily inducing the dispersion of the carbon black primarily.

Then, when the mixed solution is mixed with the first polyamic acid, as the second polyamic acid is easily mixed with the first polyamic acid, the carbon black that has already been dispersed rapidly mixes with the second polyamic acid and the first polyamic acid in the first half. Or may be dispersed. The above may be a major advantage of the manufacturing method according to the present invention.

In one specific example, an organic solvent may be used in preparing the first polyamic acid, the second polyamic acid, and the black crude liquid.

Non-limiting examples of organic solvents that can be used in these steps may be aprotic polar solvents.

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.

For example, the method of polymerizing the first polyamic acid and the second polyamic acid,

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

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

(3) After putting some components of the diamine monomer in the organic solvent, and mixed some components of the dianhydride monomer in the ratio of about 95 mol% to 105 mol% with respect to the reaction component, the remaining diamine monomer component is added thereto Successively adding the remaining dianhydride monomer component to polymerize the diamine monomer and the dianhydride monomer so as to be substantially equimolar;

(4) After the dianhydride monomer is put in the organic solvent, some components of the diamine compound are mixed at a ratio of 95 mol% to 105 mol% with respect to the reaction component, and then another dianhydride monomer component is added and the remaining Adding a diamine monomer component so that the diamine monomer and the dianhydride monomer are substantially equimolar and polymerized; And

(5) Some diamine monomer components and some dianhydride monomer components are reacted in excess in an organic solvent to form a first polymer, and some diamine monomer components and some dianhydride monomer components in another organic solvent. After reacting to make an excess of any one to form a second polymer, and then mixing the first and second polymers, and complete the polymerization, when the diamine monomer component is excessive when forming the first polymer When the dianhydride monomer component is excessive in the second polymer and the dianhydride monomer component is excessive in the first polymer, the diamine monomer component is excessive in the second polymer, and the first and second polymers are mixed. The total diamine monomer component and dianhydride monomer component used in these reactions are substantially equimolar. The method of superposing | polymerizing so that it may be mentioned, etc. will be mentioned.

However, the above method is only an example to assist in the practice of the present invention, and the scope of the present invention is not limited thereto, and any known method may be used.

On the other hand, the first polyamic acid, the second polyamic acid and / or black for the purpose of improving various properties of the film, such as the sliding, thermal conductivity, conductivity, corona resistance, loop hardness of the polyimide film derived from the precursor composition In the preparation of the crude liquid, a filler may be added. 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 the 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 polyamic acid solids of the precursor composition. to be.

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.

Meanwhile, the obtaining of the polyimide film may include forming a polyimide film by imidating the gel film after preparing the gel film by forming the precursor composition on a support and drying the film.

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.

The process of 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 to a tenter and then heat treated at a variable temperature ranging from 50 ° C. to 500 ° C., specifically 150 ° C. to 500 ° C. to remove water, residual solvent, 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 imidation method includes a chemical imidization process 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 carrying out the chemical imidization process, the type and amount of the dehydrating agent and the imidating 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 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 onto the support. The precursor composition is dried at a variable temperature in the range of 50 ° C. to 200 ° C., specifically 80 ° C. to 200 ° 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 600 ° C., specifically 150 ° C. to 600 ° 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.

The polyimide film according to the invention comprises a first polyimide chain, a second polyimide chain and carbon black. Such a polyimide film may be inherent to desired levels of mechanical properties and basic resistance which are difficult to be compatible with each other as the properties of each polyimide chain complementarily act, and have high crystallinity and low light transmittance. Has an advantage.

In particular, the polyimide film of the present invention is excellent in base resistance despite having a thin thickness of 8 μm or less, and thus carbon black dropout can be significantly suppressed even when the base component is exposed.

An advantage of the production process according to the invention is that it includes a method which can facilitate the dispersion of carbon black.

Specifically, in the production method of the present invention, by mixing carbon black in the form of a black crude liquid with a relatively low viscosity second polyamic acid, dispersion of the carbon black can be easily induced primarily, and then the mixed solution is first polyamic acid. When mixed in, the carbon black that has already been dispersed can quickly blend and / or disperse with the second polyamic acid throughout the first polyamic acid as the second polyamic acid is easily mixed with the first polyamic acid.

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 1-1 Polymerization of First Polyamic Acid

As a 1st polyamic-acid solution polymerization process, 407.5g of DMF was added as a solvent to the 1 L reactor in nitrogen atmosphere.

After the temperature was set at 25 ° C., 13.26 g of ODA and 21.48 g of PPD were added as a diamine monomer, and stirred for about 30 minutes to confirm that the monomer was dissolved. Then, 57.76 g of PMDA was divided and finally added at a viscosity of 250,000 cP The final dose was adjusted to be cP.

After the addition, the mixture was stirred for 1 hour while maintaining the temperature to obtain a first polyamic acid solution having a final viscosity of 260,000 cP.

Preparation Example 1-2 Polymerization of Second Polyamic Acid

As a polymerization process of the second polyamic acid solution, 425 g of DMF was added as a solvent to a 1 L reactor under a nitrogen atmosphere.

After the temperature was set at 25 ° C., 37.38 g of TPE-R was added as a diamine monomer, and stirred for about 30 minutes to confirm that the monomer was dissolved. Then, 37.62 g of s-BPDA was added and the final viscosity was 30,000 cP at 5,000 cP. Small amount was added so as to be.

After the addition, the mixture was stirred for 2 hours while maintaining the temperature to obtain a second polyamic acid solution having a final viscosity of 5,500 cP.

Preparation Example 1-3: Preparation of Mixed Liquid of Black Mixture and Second Polyamic Acid

30 g of carbon black was mixed with 70 g of DMF and 0.1 g of a dispersant BYK-1162, and then a black crude liquid having an average particle diameter of 0.5 μm was prepared using a milling machine.

24.5 g of the second polyamic acid solution prepared in Preparation Example 1-2 and 32 g of the black crude liquid were mixed with 43.5 g of DMF to prepare a mixed solution.

Preparation Example 1-4: Preparation of Ultra-thin Black Polyimide Film

13.3 g of the mixed solution prepared in Preparation Example 1-3 was mixed with 40.5 g of the first polyamic acid solution prepared in Preparation Example 1-1, 3.47 g of isoquinoline (IQ) and 16.47 g of acetic anhydride (AA) as a catalyst. And, after adding 5.89 g of DMF, the mixture was uniformly mixed, cast to 70 ㎛ using a doctor blade on a SUS plate (100SA, Sandvik) and dried at a temperature range of 100 ℃ to 200 ℃.

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 pin frame to remove about 86% by weight of the first polyimide chain and 5% by weight of the second polyimide relative to the total weight of the polyimide film. A 7.5 μm thick polyimide film was prepared comprising the mid chain and 9 wt% carbon black.

<Example 2>

The amounts of the first polyamic acid solution and the second polyamic acid solution were adjusted so that the polyimide film contained about 88% by weight of the first polyimide chain and 3% by weight of the second polyimide chain relative to the total weight thereof. Except that, a polyimide film having a thickness of 7.5 ㎛ was prepared in the same manner as in Example 1.

<Example 3>

The amounts of the first polyamic acid solution and the second polyamic acid solution were adjusted so that the polyimide film contained about 84% by weight of the first polyimide chain and 7% by weight of the second polyimide chain relative to the total weight thereof. Except that, a polyimide film having a thickness of 7.5 ㎛ was prepared in the same manner as in Example 1.

<Example 4>

The first polyamic acid solution, the second polyamic acid, such that the polyimide film comprises about 92% by weight of the first polyimide chain, 3% by weight of the second polyimide chain and 5% by weight of carbon black relative to its total weight A 7.5 μm-thick polyimide film was prepared in the same manner as in Example 1, except that the amount of the solution and the carbon black was adjusted.

Comparative Example 1

Preparation Example 1-2 was omitted, and Preparation of the mixed solution was omitted in Preparation Example 1-3, and the dosage amount in Preparation Example 1-4 to include about 91 wt% of the first polyimide chain and 9 wt% of carbon black. A polyimide film having a thickness of 7.5 μm was prepared in the same manner as in Example 1 except that the black crude liquid was directly mixed with the first polyamic acid.

Comparative Example 2

The amounts of the first polyamic acid solution and the second polyamic acid solution were adjusted so that the polyimide film contained about 90% by weight of the first polyimide chain and 1% by weight of the second polyimide chain relative to the total weight thereof. Except that, a polyimide film having a thickness of 7.5 ㎛ was prepared in the same manner as in Example 1.

Comparative Example 3

The amounts of the first polyamic acid solution and the second polyamic acid solution were adjusted so that the polyimide film contained about 80% by weight of the first polyimide chain and 11% by weight of the second polyimide chain relative to the total weight thereof. Except that, a polyimide film having a thickness of 7.5 ㎛ was prepared in the same manner as in Example 1.

<Comparative Example 4>

Omitting Preparation Examples 1-3, the first polyamic acid solution and the second, such that the polyimide film comprises about 95% by weight of the first polyimide chain, 5% by weight of the second polyimide chain, relative to its total weight A polyimide film having a thickness of 7.5 μm was prepared in the same manner as in Example 1, except that the amount of the polyamic acid solution was adjusted and mixed.

Comparative Example 5

The first polyamic acid solution, the second polyamic acid, such that the polyimide film comprises about 92% by weight of the first polyimide chain, 5% by weight of the second polyimide chain, and 3% by weight of carbon black, relative to its total weight A 7.5 μm-thick polyimide film was prepared in the same manner as in Example 1, except that the amount of the solution and the carbon black was adjusted.

Comparative Example 6

The first polyamic acid solution, the second polyamic acid, such that the polyimide film comprises about 80% by weight of the first polyimide chain, 5% by weight of the second polyimide chain, and 15% by weight of carbon black, relative to its total weight A 7.5 μm-thick polyimide film was prepared in the same manner as in Example 1, except that the amount of the solution and the carbon black was adjusted.

Comparative Example 7

About 86 wt% of the first polyimide chain, 5 wt%, based on the total weight of the polyimide film in the same manner as in Example 1, except that Preparation Example 1-2 was changed to the following to prepare a second polyamic acid. A 7.5 μm thick polyimide film was prepared comprising a second polyimide chain of 9 wt% carbon black.

-As a polymerization process of the second polyamic acid solution, 425 g of DMF was added to a 1 L reactor under a nitrogen atmosphere as a solvent. After the temperature was set at 25 ° C., 30.51 g of ODA was added as a diamine monomer, and stirred for about 30 minutes to confirm that the monomer was dissolved. Then, 43.49 g of s-BPDA was separately added and the final viscosity was adjusted to 5,000 cP to 30,000 cP. A small amount was added. After the addition, the mixture was stirred for 1 hour while maintaining the temperature to obtain a second polyamic acid solution having a final viscosity of 5,500 cP.

<Comparative Example 8>

The second polyamic acid solution described in Comparative Example 7 was used, such that the polyimide film comprises about 88% by weight of the first polyimide chain and 3% by weight of the second polyimide chain relative to its total weight. A 7.5 μm-thick polyimide film was prepared in the same manner as in Example 1, except that the amounts of the mixed acid solution and the second polyamic acid solution were adjusted.

Comparative Example 9

The second polyamic acid solution described in Comparative Example 7 was used, so that the polyimide film comprises about 84% by weight of the first polyimide chain, 7% by weight of the second polyimide chain, relative to its total weight; A 7.5 μm-thick polyimide film was prepared in the same manner as in Example 1, except that the amounts of the mixed acid solution and the second polyamic acid solution were adjusted.

Experimental Example: Evaluation of Physical Properties of Polyimide Film

The polyimide films prepared in Examples 1 to 4 and Comparative Examples 1 to 9, respectively, were measured in the following manner to measure base resistance, light transmittance, tensile strength, modulus, and crystallinity, and the results are shown in the following table. We summarized in 1.

1) Base resistance test

The base resistance index was measured using test method (a).

2) Light transmittance test

The light transmittance was measured in the visible region using an optical transmittance measuring device (Model: ColorQuesetXE, manufacturer: HunterLab).

3) tensile strength

Tensile strength was measured by the method given in KS6518.

4) modulus

Modulus was measured by the method set forth in ASTM D882, using the Instron 5564 model.

5) Crystallinity

Crystallinity was measured by X-ray diffraction (XRD) analysis. In general, in the case of the amorphous polymer, a peak occupying a wide area comes out. However, when the polymer chain includes a crystalline part, a partly sharp diffraction peak and a wide area appear simultaneously. Here, the degree of crystallinity can be measured by comparing the intensity and relative area of the two peaks.

Ratio ^* Second PAA ^** Monomer Basic resistance
(%) Light transmittance
(%) The tensile strength
(kgf / cm ³⁾ Modulus
(GPa) Crystallinity
(%) Example 1 86: 5: 9 TPE-R; BPDA 75 0.04 210 3.1 70 Example 2 88: 3: 9 TPE-R; BPDA 73 0.07 200 3.0 65 Example 3 84: 7: 9 TPE-R; BPDA 81 0.03 215 3.2 76 Example 4 92: 3: 5 TPE-R; BPDA 70 0.09 210 3.15 65 Comparative Example 1 91: 0: 9 none 54 0.13 190 2.9 0 Comparative Example 2 90: 1: 9 TPE-R; BPDA 56 0.20 190 2.9 30 Comparative Example 3 80: 11: 9 TPE-R; BPDA 85 0.01 165 2.4 89 Comparative Example 4 95: 5: 0 TPE-R; BPDA 78 65 210 3.2 70 Comparative Example 5 92: 5: 3 TPE-R; BPDA 72 13 215 3.1 70 Comparative Example 6 80: 5: 15 TPE-R; BPDA 68 0.00 140 2.0 70 Comparative Example 7 86: 5: 9 ODA; BPDA 70 0.13 185 2.9 53 Comparative Example 8 88: 3: 9 ODA; BPDA 68 0.13 180 2.85 49 Comparative Example 9 84: 7: 9 ODA; BPDA 72 0.13 190 2.95 58

_{* Weight ratio of 1st polyamic acid: 2nd polyamic acid: carbon black}

_{** second PAA = second polyamic acid}

As shown in Table 1, Examples 1 to 4 exhibited a relatively high crystallinity, light transmittance of 0.09 or less, very good shielding and light shielding functions, and also excellent base resistance. In addition, Examples 1 to 4 exhibited a level of compliance with tensile strength and modulus, which are mechanical properties.

On the other hand, Comparative Example 1, which contains no second polyimide chain at all, shows very poor base resistance, and the crystallinity is about 0, which is extremely low. The characteristics did not show superiority. From this, it can be seen that the inclusion of the second polyimide chain according to the present invention plays a major role in improving the base resistance, shielding, and light shielding properties.

Comparative Example 2 exhibited low base resistance as it contained a small amount of second polyimide chain outside the scope of the present invention.

Comparative Example 3 contains an excess of the second polyimide chain outside the scope of the present invention, but it can be seen that the tensile strength and modulus are significantly reduced. From these results it can be understood that it is important that the first polyimide chain and the second polyimide chain are contained within the scope of the present invention.

Comparative Examples 4 to 6 show that the inclusion of carbon black in the scope of the present invention is preferable in terms of achieving a low light transmittance, and in particular, Comparative Example 6 is due to the excessive amount of carbon black even though the second polyimide chain is contained. Due to the low base resistance.

Comparative Examples 7 to 9 implement the second polyimide chain using monomers different from the monomers disclosed in the present invention. Comparing these comparative examples with Examples 1 to 3, it can be seen that the results of the examples are better when the second polyimide chain is contained in the same content. In addition, Comparative Examples 7 to 9 have a low crystallinity, and it can be seen that there is no effect of improving shielding and light shielding properties as compared with the Examples.

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.

Claims (15)

A first polyamic acid polymerized with a first diamine containing a first dianhydride and up to two benzene rings;
A second polyamic acid polymerized with a second diamine containing a second dianhydride and three or more benzene rings; And
Carbon black;
Is prepared by imidizing the precursor composition comprising a,
A polyimide film having a crystallinity of 65% or more, a light transmittance of 0.09 or less, a base resistance index of 70% or more, and a thickness of 8.0 μm or less, evaluated based on the thickness of the polyimide film before and after base component exposure. The method of claim 1,
The first polyamic acid forms a first polyimide chain through imidization,
The second polyamic acid is a polyimide film to form a second polyimide chain through imidization. The method of claim 2,
At least a portion of the first polyimide chain and the second polyimide chain are crosslinked with each other through imidization. The method of claim 1,
The first polyamic acid has a viscosity of 50,000 cP to 300,000 cP measured at 23 ° C. when the solid content is 15% by weight.
The second polyamic acid has a viscosity of 5,000 cP to 30,000 cP measured at 23 ° C. when the solid content is 15% by weight. The method of claim 1,
Regarding the total weight of the polyimide film,
80 to 92% by weight of the first polyimide chain,
3 to 10 weight percent of a second polyimide chain, and
5 to 10% by weight of carbon black containing an average particle diameter of 0.1 to 5 ㎛,
The polyimide film whose thickness of a film is 7.5 micrometers or less. The method of claim 5,
Regarding the total weight of the polyimide film,
83 to 92 weight percent of the first polyimide chain,
Polyimide film comprising 5 to 7% by weight of the second polyimide chain. The method of claim 1,
The first dianhydride is pyromellitic dianhydride (or PMDA),
The second dianhydride is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (or s-BPDA) and / or 2,3,3', 4'-biphenyltetracarboxylic A polyimide film that is rick dianhydride (or a-BPDA). The method of claim 1,
The first diamine,
1) Diamines with one benzene ring: 1,4-diaminobenzene (or paraphenylenediamine, PDA, PPD), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-dia Minotoluene, 3,5-diaminobenzoic acid (DABA);
2) diamines having two benzene rings: 4,4'-diaminodiphenylether (or oxydianiline, ODA), 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylmethe Phosphorus (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoro) Methyl) -4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane Phosphorus, 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'-dimeth Oxybenzidine, 3,3'-diaminodiphenylether, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 3,3'-diaminodiphenylsulfide, 3,4 '-Diaminodiphenylsulfide, 4,4'-dia Nodiphenylsulfide, 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 and 4,4'-diaminodiphenylsulfoxide Polyimide film which is at least 1 sort (s) chosen from the group which consists of a side. The method of claim 1,
The second diamine is 1,3-bis (4-aminophenoxy) benzene (TPE-R) and / or 1,4-bis (3-aminophenoxy) benzene (TPE-Q). The method of claim 1,
A polyimide film having a light transmittance of 0.07 or less and a base resistance index of 75% or more, evaluated based on the thickness of the polyimide film before and after base component exposure. The method of claim 1,
The crystallinity of the polymer in the film state is 70% or more,
Tensile strength is more than 200 kgf / cm ³ ,
Polyimide film having a modulus of 3 GPa or more. As a method of manufacturing the polyimide film according to claim 1,
Polymerizing a first polyamic acid from the first dianhydride and the first diamine;
Polymerizing a second polyamic acid from a second dianhydride and a second diamine;
Preparing a black crude liquid including a carbon black having an average particle diameter of 0.1 to 5 μm using a milling machine;
Preparing a mixed liquid by mixing the second polyamic acid and the black crude liquid;
Preparing a precursor composition by mixing the mixed solution with the first polyamic acid; And
Imidating the precursor composition to obtain a polyimide film. The method of claim 12,
The obtaining of the polyimide film may include forming a polyimide film by forming the precursor composition on a support and drying the gel film to form a polyimide film, and then imidating the gel film. A coverlay comprising the polyimide film of claim 1. An electronic device comprising the coverlay according to claim 14.