KR101906394B1 - Ultra Thin Black Polyimide Film and Method For Preparing The Same - Google Patents

Abstract

The present invention relates to a method for preparing a polyimide film obtained by mixing two or more different polyamic acids and imidizing the mixture. The method comprises the steps of: (a) polymerizing a first polyamic acid with excellent strength from a first dianhydride and a first diamine; (b) polymerizing a second polyamic acid with excellent chemical resistance from an end-capping agent, a second dianhydride, and a second diamine; (c) producing carbon black with an average particle diameter of 0.1-5 μm by using a milling machine and producing a black solution; (d) mixing the second polyamic acid and the black solution to produce a mixture solution; and (e) mixing and dispersing the mixture solution in the first polyamic acid, and forming a film on a support, and conducting a heat treatment to carry out imidization.

Description

TECHNICAL FIELD [0001] The present invention relates to an ultra thin black polyimide film,

The present invention relates to an ultra-thin black polyimide film and a method for producing the same.

In general, polyimide (PI) resin refers to a high heat-resistant resin prepared by preparing a polyamic acid derivative by combining an aromatic dianhydride, an aromatic diamine or an aromatic diisocyanate in solution, and then dehydrating and cyclizing at a high temperature to imidize it.

The polyimide resin is obtained by reacting an aromatic acid dianhydride such as pyromellitic dianhydride (PMDA) or biphenyltetracarboxylic dianhydride (BPDA) and an anhydride such as oxydianiline (ODA), p-phenylenediamine (p-PDA) is produced by polymerizing an aromatic diamine component such as m-phenylenediamine (m-PDA), methylenedianiline (MDA), and bisaminophenylhexafluoropropane (HFDA).

Polyimide resin is an insoluble and non-fusible ultra-high temperature resistant resin. It has excellent heat resistant oxidizing property, heat resistance property, radiation resistance property, low temperature property, chemical resistance and so on. It is a high heat resistant material such as automobile material, , Insulating films, semiconductors, and electrode protective films for TFT-LCDs.

Recently, it is widely used as a coverlay in portable electronic devices and communication devices.

The coverlay is for protecting electronic parts such as a printed wiring board and a lead frame of a semiconductor integrated circuit, and is required to have properties such as thinning and slimness. In recent years, the coverlay has been used for security, portability, visual effects, Optical properties as well as hiding properties are also required.

On the other hand, when the polyimide film is used as the coverlay of the printed wiring board, the manufacturing process of the printed wiring board includes a drilling process, a plating process, a desmear process, and a cleaning process. The coverlay composed of the polyimide film is inevitably exposed to the alkaline solution.

However, it is generally known that polyimide is very vulnerable to alkali such as decomposed or denatured when exposed to an alkaline environment.

Therefore, when a polyimide film is used as a coverlay, it is inevitably exposed to an alkali, whereby the polyimide is decomposed or denatured, and the thickness of the film is thinned or the physical properties thereof are changed, There is a problem that the reliability of a manufactured product is remarkably lowered.

Therefore, there is a high need for a technique capable of fundamentally solving such problems.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments, and as a result, they have been constructed to include a step of mixing and emulsifying a mixed solution obtained by mixing a second polyamic acid and a black tank liquid into a first polyamic acid , An ultra-thin black polyimide film having a thickness of 8 탆 or less and excellent in optical properties such as gloss and transmittance, mechanical stability, and resistance to alkali can be provided.

Further, by adding the end blocker in the process of polymerizing the second polyamic acid, the storage stability of the mixed solution containing the second polyamic acid and the black tank liquid can be improved.

This makes it possible to improve the reliability of the physical properties of the polyimide film without depending on the raw material storage period.

In order to achieve this object, the present invention provides a process for producing a polyimide film obtained by mixing and imidizing two or more different polyamic acids,

(a) polymerizing a first polyamic acid having excellent rigidity from a first dianhydride and a first diamine;

(b) polymerizing a second polyamic acid having excellent chemical resistance from an end-capping agent, a second dianhydride and a second diamine;

(c) preparing carbon black having an average particle diameter of 0.1 to 5 탆 by using a milling machine and preparing a black tank liquid containing the carbon black;

(d) mixing the second polyamic acid and the black tank liquid to prepare a mixed solution; And

(e) mixing and dispersing the mixture solution in the first polyamic acid, forming a film on the support, and heat treating the mixture to imidize the ultra-thin black polyimide film.

Specifically, the first polyamic acid and the second polyamic acid may form a first polyimide chain and a second polyimide chain through an imidization step, respectively.

In addition, the first polyamic acid and the second polyamic acid may form a structure in which at least a part of the first polyimide chain and the second polyimide chain are crosslinked to each other through the imidization step.

Wherein the film comprises a first polyimide chain having a stiffness of 80 to 93% by weight, a second polyimide chain having an excellent chemical resistance of 2 to 15% by weight, and a polyimide chain having an average of 3 to 10% by weight based on the total weight of the polyimide film A carbon black having a particle diameter of 0.1 to 5 占 퐉, an alkali resistance index evaluated based on the thickness of the polyimide film is 70% or more, and a thickness of the film may be 8.0 占 퐉 or less.

The first dianhydrides and the second dianhydrides may each independently be selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA) , And benzophenone tetracarboxylic dianhydride (BTDA), and the first diamines and the second diamines are each independently selected from the group consisting of 1,4-phenylenediamine (PPD) , 4,4'-oxydianiline (ODA), 3,4'-oxydianiline, 2,2-bis [4 '- (4-aminophenoxy) phenyl] propane (BAPP) Methylene dianiline (MDA), and 1,3-bis (4-aminophenoxy) benzene (TPE-R).

Specifically, the first dianhydride may not contain a soft dianhydride, or may contain less than 10 mol% of a flexible dianhydride with respect to the dianhydride monomer constituting the first polyamic acid, , And the soft dianhydride and the soft diamine do not contain soft diamines or contain less than 80 mol% of soft diamines relative to the whole diamines monomers constituting the first polyamic acid, Two or more rings may be included.

Also, the second dianhydride may include at least 80 mol% of a dianhydride based on the entire dianhydride monomer constituting the second polyamic acid, and the second diamine may include all of the diamine monomers constituting the second polyamic acid , And the soft dianhydride and the soft diamine may each contain two or more benzene rings in the molecular structure.

In a more specific example, the flexible dianhydride is selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA) It may be at least one selected.

The soft diamines include 4,4'-oxydianiline (ODA), 3,4'-oxydianiline, 2,2-bis [4 '- (4-aminophenoxy) phenyl] propane (BAPP) , 4,4'-methylene dianiline (MDA) and 1,3-bis (4-aminophenoxy) benzene (TPE-R).

Meanwhile, the second polyamic acid may have a polymerization viscosity ranging from 100,000 to 150,000 cp at a solid content of 15%, and the mixture may have a concentration ranging from 2 to 10% by weight and a viscosity ranging from 50 to 1000 cp.

The end blocker may be included in the range of 0.05 to 1% by weight based on the weight of the solid content of the second polyamic acid.

Specifically, the end blocker may be at least one member selected from the group consisting of phthalic anhydride (PA), malein anhydride (MA) and glutaric anhydride (GA).

The present invention can also provide an ultra thin black polyimide film produced by the above production method.

The present invention also provides a polyimide film obtained by mixing and imidizing two or more different polyamic acids,

Based on the total weight of the polyimide film, a first polyimide chain having 80 to 93 wt%

A second polyimide chain having an excellent chemical resistance of 3 to 15% by weight, and

And carbon black having an average particle size of 0.1 to 5 占 퐉 in an amount of 3 to 10% by weight,

An ultra-thin black polyimide film having an alkali resistance index of 70% or more, which is evaluated based on the thickness of the polyimide film.

The film may have a thickness of 3 to 7.5 占 퐉, a light transmittance in a visible light region of 10% or less, and a glossiness of 10 to 50%.

The present invention can also provide a coverlay including the ultra thin black polyimide film, and can provide an electronic device including the coverlay.

As described above, the method of producing an ultra-thin black polyimide film according to the present invention is a method of producing an ultra-thin black polyimide film having a thickness of 8 μm or less, And has low light transmittance in the visible light region.

In addition, the storage stability of the mixed solution containing the second polyamic acid and the black tank solution is improved, so that the reliability of the polyimide film can be improved without depending on the storage period of the raw material.

In addition, the polyimide film according to the present invention has excellent mechanical and chemical resistance as well as excellent resistance to alkali, and can be used for a slimming device, a coverlay, an insulating film, a semiconductor device and the like.

1 is an external view of the FCCL produced using the ultra-thin black polyimide film of Comparative Example 1 after exposure to alkali.
2 is an external view of the FCCL produced using the ultra thin black polyimide film of Example 1 after exposure to alkali.

Hereinafter, the present invention will be described in more detail.

A method for producing an ultra thin black polyimide film according to the present invention is a method for producing a polyimide film obtained by mixing and imidizing two or more different polyamic acids, wherein a first dianhydride and a first diamine, A step of polymerizing a polyamic acid, a step of polymerizing a second polyamic acid having excellent chemical resistance from an end blocker, a second dianhydride and a second diamine, a carbon black having an average particle diameter of 0.1 to 5 탆 is prepared using a milling machine Preparing a mixed liquid by mixing the second polyamic acid and the black tank liquid, mixing the first polyamic acid with the mixed liquid and dispersing the mixture, forming a film on the substrate, .

In addition, the first polyamic acid and the second polyamic acid may form a first polyimide chain and a second polyimide chain, respectively, through an imidation step

Specifically, the first polyamic acid and the second polyamic acid may form a structure in which at least a part of the first polyimide chain and the second polyimide chain are crosslinked to each other through the imidization step.

That is, in the present invention, the step of polymerizing and then imidizing a polyamic acid having excellent rigidity and a second polyamic acid having excellent chemical resistance are respectively included, whereby the first polyimide chain having excellent rigidity and the second polyimide having excellent chemical resistance The polyimide chain is also retained in the polyimide film so that the polyimide film can improve the chemical resistance to a level corresponding to the second polyimide chain while maintaining the mechanical rigidity of the level corresponding to the first polyimide chain have.

Polymerized polyimides with low ductility are excellent in mechanical stiffness but relatively low in chemical resistance. Polymerized polyimides with high ductility have excellent chemical resistance and relatively low mechanical rigidity.

In order to simultaneously secure the mechanical stiffness and chemical resistance of the polyimide film, when a polyimide film is produced by polymerizing a polyamic acid by mixing a monomer having a low ductility and a monomer having a high ductility, a medium mechanical rigidity A polyimide film having chemical resistance can be obtained and a polyimide film having both mechanical rigidity and chemical resistance as in the present invention can not be obtained.

In other words, the manufacturing method according to the present invention maintains the properties of the respective polyimide chains even after the imidization step, as compared with the production method of simply polymerizing the polyamic acid solution by mixing monomers having different properties, It is possible to satisfy not only the mechanical properties but also the chemical properties of the resin.

In the step of polymerizing the first polyamic acid or the second polyamic acid, an aprotic polar solvent may generally be used as the amide-based solvent.

Examples thereof include N, N'-dimethylformamide (DMF), N, N'-dimethylacetamide and N-methyl-pyrrolidone (NMP) Can be used in combination.

In addition, the dianhydride and the diamine may be in the form of powder, lump and solution. In the initial stage of the reaction, they are added in powder form to proceed the reaction. .

For example, dianhydride and diamine may be added in powder form to conduct the reaction, and dianhydride may be added in the form of a solution to allow the viscosity of the first polyamic acid or the second polyamic acid to be maintained within a certain range have.

On the other hand, a catalyst may be further added to the mixture of the first polyamic acid, the second polyamic acid, and the carbon black, and then applied to the support.

At this time, it is possible to use a dehydration catalyst composed of an anhydrous acid such as acetic anhydride and tertiary amines such as isoquinoline, p-picoline and pyridine as a catalyst, and a mixture of anhydrous acid / amines or an anhydride / amine / Can be used.

The amount of anhydrous acid may be calculated in terms of the molar ratio of the o-carboxylic amide functional group in the first polyamic acid solution and the second polyamic acid solution, and may be 1.0 to 5.0 mol, May be calculated in terms of the molar ratio of the o-carboxylic amide group in the polyamic acid solution, and may be specifically 0.2 to 3.0 mols.

Also, the step of heat-treating the polyamic acid solution coated on the support to gelation may have a gelling temperature of 100 to 250 ° C.

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

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

The gelled film is separated from the support and then heat-treated to complete drying and imidization.

The heat treatment temperature may be 100 to 500 占 폚, and the heat treatment time may be 1 to 30 minutes. The gelled film can be heat-treated by being fixed to a supporting base such as a pin type frame or a clip type which can be fixed at the time of heat treatment.

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

Specifically, it is necessary to minimize the shaking at the time when the polyamic acid solution is discharged from the T-die to the endless belt and land in a film form. To this end, in order to form a general polyimide film The air can be supplied at a pressure lower than the pressure used at the time of, for example, 10 to 40 mm H ₂ O.

In this case, 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, Lt; / RTI >

[Mathematical Expression]

Dissolved amount from T-die / time from T-die = specific gravity of film * (T-die cross section) * (speed of endless belt)

At the laboratory level, it is possible to obtain an ultra thin film polyimide film by controlling the casting thickness. However, in the mass production process, it is possible to realize an ultra thin film thickness of 8 μm or less when the above range is satisfied.

In addition, in order to prevent the film from being broken during the heat treatment process in a heat treatment using a device such as a tenter dryer after being fixed to a frame of a pin type, it is preferable that the heat treatment temperature of the yellow polyimide film Lt; 0 > C.

Further, the imidized film may be subjected to a cooling treatment at 20 to 30 占 폚 to form a film.

On the other hand, the film produced by the method of producing the ultra thin black polyimide film has a first polyimide chain excellent in rigidity of 80 to 93% by weight based on the total weight of the polyimide film, a second polyimide chain having 2 to 15% A second polyimide chain, and carbon black having an average particle diameter of 0.1 to 5 占 퐉 of 3 to 10% by weight, wherein the alkali resistance index evaluated on the basis of the thickness of the polyimide film is 70% or more, Or less.

That is, the film produced by the method for producing an ultra thin black polyimide film of the present invention contains a second polyimide chain having a small amount of chemical resistance ranging from 3 to 15% by weight, so that the level corresponding to the first polyimide chain It is possible to improve the chemical resistance at a level corresponding to the second polyimide chain while maintaining the physical properties such as high mechanical strength and insulating property at a desired level and in particular to improve the alkali resistance index.

If the content of the second polyimide chain is less than 2% by weight, it is difficult to achieve the desired chemical resistance. Conversely, when the content of the second polyimide chain exceeds 15% by weight, It is not preferable since the thermal properties may be deteriorated.

As described above, polyimide is generally vulnerable to alkali such as decomposed or denatured when exposed to an alkaline environment.

Resistance to alkali means a property that the polyimide film is not easily decomposed or denatured even when exposed to an alkaline environment.

As an index for evaluating the alkali resistance, a method of measuring the thickness change of the film before and after the exposure after exposing the polyimide film to the NaOH solution and the dispersion liquid can be used.

The evaluation method of the alkali resistance resistance index (evaluation method (a)) is as follows.

The polyimide film is subjected to corona treatment on both sides and then joined with a polyimide film, a bonding sheet (adhesive) and a copper foil structure using a hot press at a pressure of 50 kgf and a temperature of 160 ° C. for 30 minutes to prepare a flexible circuit board (FCCL) sample.

The FCCL cut in 4 * 10 cm was exposed to 10% NaOH solution at 55 ° C for 3 minutes, exposed to distemir (10% NaMnO ₄ + 4% NaOH) at 55 ° C for 5 minutes, , The thickness of the film is measured, and the degree of change in thickness after exposure is expressed as a percentage of the thickness before exposure compared with the thickness before exposure to the NaOH solution and the dismear solution.

Since the ultra-thin black polyimide film produced according to the production method of the present invention can exist at the same time in a structure in which at least a part of the polyimide chain having excellent rigidity and the polyimide chain having excellent chemical resistance are mutually crosslinked, And chemical properties such as resistance can be excellent.

Further, through such a structure, even if the first polyimide chain having a relatively low chemical resistance is decomposed by exposure to an alkali, the second polyimide having excellent chemical resistance supports the entire film, and an external change such as a thickness of the polyimide film Can be remarkably reduced.

On the other hand, the first dianhydride and the second dianhydride are each independently selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA) , And benzophenone tetracarboxylic dianhydride (BTDA).

The first diamines and the second diamines are each independently selected from the group consisting of 1,4-phenylenediamine (PPD), 4,4'-oxydianiline (ODA), 3,4'-oxydianiline, (4-aminophenoxy) phenyl] propane (BAPP), 4,4'-methylene dianiline (MDA) and 1,3- R) may be used.

Specifically, the first dianhydride may not contain a soft dianhydride, or may contain less than 10 mol% of a flexible dianhydride with respect to the dianhydride monomer constituting the first polyamic acid, , And the soft dianhydride and the soft diamine do not contain soft diamines or contain less than 80 mol% of soft diamines relative to the whole diamines monomers constituting the first polyamic acid, Two or more rings may be included.

Specifically, the first dianhydride may not contain a soft dianhydride, or may contain less than 5 mol% of a flexible dianhydride with respect to the total dianhydride monomer constituting the first polyamic acid, and the first diamine May contain no soft diamines or may contain less than 75 mol% of soft diamines relative to the total of the diamines monomers constituting the first polyamic acid.

More specifically, the first dianhydride does not contain a soft dianhydride, or contains less than 3 mol% of a flexible dianhydride with respect to the dianhydride monomer constituting the first polyamic acid, and the first diamine May not contain soft diamines or may contain less than 70 mol% of soft diamines relative to the total diamines of the diamines constituting the first polyamic acid.

At this time, if the first dianhydride constituting the first polyamic acid comprises a soft dian above the range over the entire dianhydride monomer, or the first diamine constituting the first polyamic acid comprises the dianemic monomer When a soft diamine having the above range is included, mechanical rigidity may be lowered, which is undesirable.

On the other hand, the second dianhydride may contain at least 80 mol% of the dianhydrides relative to the total of the dianhydride monomers constituting the second polyamic acid, and the second diamines may include all of the diamine monomers constituting the second polyamic acid , And the soft dianhydride and the soft diamine may each contain two or more benzene rings in the molecular structure.

Specifically, the second dianhydride may include at least 90 mol% of a dianhydride relative to the total dihydroxyl monomer constituting the second polyamic acid, and the second diamine may include a diamine monomer constituting the second polyamic acid It may contain at least 90 mol% of soft diamines relative to the whole.

More specifically, the second dianhydride may include at least 95 mol% of a flexible dianhydride with respect to the total of the dianhydrides constituting the second polyamic acid, and the second diamine may include diamines constituting the second polyamic acid And 95% by mole or more of soft diamines relative to the entire monomers.

At this time, if the second dianhydride constituting the second polyamic acid contains a soft dianhydride below the range over the entire dianhydride monomer, or the second diamine constituting the second polyamic acid is contained in the entire diamine monomer Is less than the above range, it is not preferable because the chemical resistance can not be achieved to a desired extent.

In one specific example, the flexible dianhydride is not particularly limited as long as it has a structure containing two or more benzene rings in the molecular structure. For example, the flexible dianhydride may be biphenyl tetracarboxylic dianhydride (BPDA ), Oxydiptalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA), and more particularly, the soft dianhydride may be BPDA It is not limited thereto.

In yet another specific example, the soft diamines are not particularly limited as long as they have a structure containing two or more benzene rings in the molecular structure. For example, the soft diamines include 4,4'-oxydianiline (ODA) , 3,4'-oxydianiline, 2,2-bis [4 '- (4-aminophenoxy) phenyl] propane (BAPP), 4,4'- methylenedianiline (4-aminophenoxy) benzene (TPE-R). More specifically, the soft diamine may be ODA but is not limited thereto.

On the other hand, in the general case, the second polyamic acid contains an amine group at the terminal so that the amine group may collide with or hydrolyze the linking sites of other compounds, thereby decreasing the molecular weight of the polymer chain and ultimately causing the second polyamic acid The viscosity of the solution may vary greatly.

Similarly, in the process of mixing the first polyamic acid and the mixed solution before the imidization step, the terminal of the first polyamic acid and the terminal of the second polyamic acid may be overlapped with each other, so that the chain length may become excessively long.

As a result, the molecular weight of the polyamic acid may increase and the viscosity of the polyamic acid solution may excessively increase, which may cause a problem of lowering the reliability of the imidization process designed based on a constant viscosity range.

On the other hand, the production process according to the present invention includes a step of introducing the end blocker in the polymerization process of the second polyamic acid, so that the amine end is blocked, so that the viscosity change as described above can be minimized, And the viscosity change is minimized even at room temperature, so that the process safety is excellent.

Specifically, the second polyamic acid may have a viscosity retention ratio of 80% or more at room temperature for 30 days.

At this time, the end blocker may be included in the range of 0.05 to 1% by weight based on the weight of the second polyamic acid, and the end blocker may include phthalic anhydride (PA), maleic anhydride (MA) And rutaric anhydride (GA), and may be at least one selected from the group consisting of PA.

As described above, the method of producing an ultra thin black polyimide film according to the present invention comprises mixing carbon black to maintain the black color of the film and to keep the gloss low, and the carbon black is 0.1 to 5 By having an average particle diameter of 占 퐉, it is possible to realize an ultra-thin black polyimide film having a film thickness of 8 占 퐉 or less.

At this time, the carbon black may be mixed with the second polyamic acid in the form of a solution in the form of a solution in the form of a solution dispersed in a solvent, and the polar solvent may include N, N'-dimethylformamide, N, N'-dimethylacetate Amide, and N-methyl-pyrrolidone.

Generally, in the process for producing a polyimide film, carbon black is mixed with a polyamic acid after a milling process together with a dispersing agent for improving dispersibility. When the dispersibility of carbon black is low, And the carbon particles may be unevenly dropped in an environment exposed to an alkali.

On the other hand, in the present invention, the carbon black in the form of black tank liquid is first mixed with the second polyamic acid to prepare a mixed solution, the dispersibility of the carbon black in the mixed liquid is firstly improved, 1 polyamic acid, and the dispersibility of the carbon black can be further improved as described above.

Specifically, the second polyamic acid may have a polymerization viscosity ranging from 100,000 to 150,000 cp at a solid content of 15%, and the mixed liquid in which the black tank liquid and the second polyamic acid are mixed may have a concentration ranging from 2 to 10% The viscosity may range from 50 to 1000 cp.

If the polymerization viscosity of the second polyamic acid or the viscosity of the mixed solution exceeds the above range, it takes a lot of time to perform the mixing process and thus the processability is deteriorated. If the viscosity is less than the above range, the dispersibility of the carbon black may be deteriorated.

When the dispersibility of carbon black is improved, there is an advantage that the deterioration of the mechanical properties of the film can be prevented while improving the hiding performance of the polyimide film.

The present invention can also provide an ultra thin black polyimide film produced by the above production method.

As described above, the ultra thin black polyimide film according to one embodiment of the present invention may have a thickness of 7.5 탆 or less, specifically 3 to 7.5 탆, more specifically 5 to 7.5 탆.

In addition, the film may have a light transmittance in the visible light range of 10% or less, or 9.7% or less, to provide a light shielding function, and a gloss of 10 to 50%, or 15 to 50% The lower the better, the better.

When the film is applied to a coverlay, an insulating film, a semiconductor or the like, the product can be made slimmer, the aesthetic characteristic can be improved, and the internal shape and the charging parts can be blocked, which is useful for security.

Also, the film may have a coefficient of thermal expansion (CTE) in the MD and TD directions of 10 to 20 ppm / ° C.

Wherein the film comprises a first polyimide chain having 80 to 93% by weight of stiffness and 2 to 15% by weight of a second polyimide chain having excellent chemical resistance, a polyimide film having an average particle diameter of 3 to 10% May be 0.1 to 5 占 퐉.

Hereinafter, the present invention will be described in more detail by way of specific examples and comparative examples. The following examples are intended to further illustrate the present invention and are not intended to limit the scope of the present invention.

≪ Example 1 >

Production Example 1-1: Polymerization of the first polyamic acid

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

After the temperature was set to 25 占 폚, 35.1 g of ODA and 6.3 g of PPD were added as diamine monomers and stirred for about 30 minutes to confirm that the monomer was dissolved. Then, 51.0 g of PMDA was added thereto in portions and the final viscosity was 250,000 cp The final dosage was adjusted to 300,000 cp.

After the addition, the mixture was stirred for 1 hour while maintaining the temperature, to polymerize the first polyamic acid solution containing less than 10% of the flexible dianhydride having a final viscosity of 260,000 cp and less than 80% by mole of the soft diamine.

Production Example 1-2: Polymerization of the Second Polyamic acid

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

After the temperature was set to 25 ° C, 30.4 g of ODA was added as a diamine monomer, stirring was continued for about 30 minutes to confirm that the monomer was dissolved, and then 44.6 g of BPDA was added thereto, and the final viscosity was changed from 100,000 cp to 150,000 cp And 0.135 g of PA was added thereto as an end blocker.

After the completion of the addition, the mixture was stirred for 1 hour while maintaining the temperature, and a second polyamic acid solution containing 80% by mole or more of each of the soft dianhydrides and soft diamines having a final viscosity of 120,000 cp and containing 0.18% .

Production Example 2-1: Preparation of a mixed solution obtained by mixing a black crude liquid and a second polyamic acid

10 g of carbon black was mixed with 89.1 g of DMF and 0.1 g of dispersant BYK-1162, and then a black tea liquid having an average particle diameter of 1.2 탆 was prepared using a milling machine.

20 g of the second polyamic acid solution prepared in Preparation Example 1-2 and 46 g of the black tank liquid were mixed with 34 g of DMF to prepare a mixed solution containing 3% of a second polyamic acid and 4.6% of carbon black.

Production Example 3-1: Preparation of ultra-thin black polyimide film

20 g of the mixed solution prepared in Preparation Example 2-1 was mixed with 100 g of the first polyamic acid solution prepared in Preparation Example 1-1, and 4.76 g of isoquinoline (IQ), 26.36 g of anhydrous acetic acid (AA) And 18.87 g of DMF were added thereto. The resulting mixture was homogeneously mixed and cast on a SUS plate (100SA, Sandvik) using a doctor blade to a thickness of 70 μm and dried at a temperature of 100 ° C. to 200 ° C.

Then, the film was peeled off from the SUS plate, fixed to the pin frame, and transferred to the hot tenter.

The film was heated in a hot tenter from 200 ° C to 600 ° C, cooled at 25 ° C and separated from the pin frame to obtain 81.6% by weight of the first polyimide chain, 3% by weight of the second polyimide Chain and black polyimide film having a thickness of 7.5 mu m including 5 wt% carbon black was prepared.

≪ Example 2 >

100 g of the first polyamic acid solution prepared in Preparation Example 1-1, 20 g of a mixed solution obtained by mixing 33.3 g of the second polyamic acid solution prepared in Preparation Example 1-2, 47 g of 10% black crude liquid and 19.3 g of DMF Was prepared in the same manner as in Example 1 except that 90 wt% of the first polyimide chain, 5 wt% of the second polyimide chain, and 5 wt% of the carbon black were contained in the polyimide film, To prepare an ultra thin black polyimide film having a thickness of 7.5 mu m.

≪ Example 3 >

100 g of the first polyamic acid solution prepared in Preparation Example 1-1 was mixed with 35.6 g of the second polyamic acid solution prepared in Preparation Example 1-2, 24.5 g of 10% black liquid and 39.8 g of DMF Was the same as that of Example 1 except that the first polyimide chain was composed of 85 wt% of the first polyimide chain, 10 wt% of the second polyimide chain, and 5 wt% of the carbon black with respect to the total weight of the polyimide film To prepare an ultra thin black polyimide film having a thickness of 7.5 탆.

<Example 4>

100 g of the first polyamic acid solution prepared in Preparation Example 1-1, 40 g of a mixed solution obtained by mixing 56.7 g of the second polyamic acid solution prepared in Preparation Example 1-2, 26 g of 10% black tank liquid and 17.3 g of DMF Was prepared in the same manner as in Example 1 except that 80 wt% of the first polyimide chain, 15 wt% of the second polyimide chain, and 5 wt% of the carbon black were contained relative to the total weight of the polyimide film To prepare an ultra thin black polyimide film having a thickness of 7.5 mu m.

&Lt; Example 5 >

As in Preparation Example 1-2, a second polyamic acid solution containing 0.18 wt% of the solid content of the end blocker was prepared in the second polyamic acid solution.

&Lt; Comparative Example 1 &

100 g of the first polyamic acid solution prepared in Preparation Example 1-1 was used, and 95% by weight of the first polyimide chain and 5% by weight of carbon, based on the total weight of the polyimide film, Black ultra-thin black polyimide film having a thickness of 7.5 탆 was prepared in the same manner as in Example 1 except that the black was included.

&Lt; Comparative Example 2 &

100 g of the first polyamic acid solution prepared in Preparation Example 1-1 was mixed with 64.3 g of the second polyamic acid solution prepared in Preparation Example 1-2, 22.5 g of 10% black liquid and 13.2 g of DMF Was the same as that of Example 1 except that it contained 75 wt% of the first polyimide chain, 20 wt% of the second polyimide chain, and 5 wt% of the carbon black with respect to the total weight of the polyimide film To prepare an ultra thin black polyimide film having a thickness of 7.5 탆.

&Lt; Comparative Example 3 &

100 g of the first polyamic acid solution prepared in Preparation Example 1-1 was mixed with 64.3 g of the second polyamic acid solution prepared in Preparation Example 1-2, 22.5 g of 10% black crude liquid and DMF Except that the first polyimide chain of 65 wt%, the second polyimide chain of 30 wt% and the carbon black of 5 wt% were included in the total weight of the polyimide film by using 84 g of the black tank liquid , And an ultra-thin black polyimide film having a thickness of 7.5 탆 was prepared in the same manner as in Example 1.

&Lt; Comparative Example 4 &

In Preparation Example 1-1, 27.2 g of ODA and 2.6 g of PPD were added as diamine monomers, and 5.2 g of PMDA and 27.2 g of BPDA as dianhydride monomers were added to the first polyamic acid solution to remove the soft dianhydride and the soft diamine in 80 Mol% of the polyimide film of Example 1 was prepared in the same manner as in Example 1,

&Lt; Comparative Example 5 &

In Preparation Example 1-2, 21.1 g of ODA and 7.6 g of PPD were added as diamine monomers, and 31.0 g of BPDA and 15.3 g of PMDA as dianhydride monomers were added to the second polyamic acid solution to remove the soft dianhydride and soft diamine in 80 Mol% of the black polyimide film of Example 1 was prepared.

&Lt; Comparative Example 6 >

A second polyamic acid solution was prepared in the same manner as in Example 5 except that the end blocker was not used in Preparation Example 2-1.

&Lt; Comparative Example 7 &

In the same manner as in Example 5 except that 0.05 g of PA was added to the second polyamic acid solution as the end blocker in Preparation Example 1-2, the endblocking agent was contained in an amount of 0.07% by weight of the solid content, and the second polyamic acid solution was prepared Respectively.

Experimental Example 1: Evaluation of gloss

The ultra-thin black polyimide film produced in each of Examples 1 to 4 and Comparative Examples 1 to 3 was measured for gloss by using a glossiness measuring device (Model: E406L, manufacturer: Elcometer) at 60 Deg.], And the results are shown in Table 1 below.

Experimental Example 2: Evaluation of transmittance

The ultra-thin black polyimide films prepared in each of Examples 1 to 4 and Comparative Examples 1 to 4 were measured for transmittance using a transmittance measuring instrument (Model: ColorQuesetXE, manufactured by Hunter Lab) The transmittance was measured by the ASTM D1003 method in the visible light region, and the results are shown in Table 1 below.

The first PI chain
(weight%) The second PI chain
(weight%) Carbon black
(weight%) Polish
(60 DEG) Transmittance
(%) Example 1 92 3 5 40 6.2 Example 2 90 5 5 39 6.0 Example 3 85 10 5 39 5.7 Example 4 80 15 5 38 5.5 Comparative Example 1 95 0 5 43 6.4 Comparative Example 2 75 20 5 36 5.4 Comparative Example 3 65 30 5 35 5.3 Comparative Example 4 92 3 5 44 6.4

Experimental Example 3: Evaluation of tensile properties

The ultra-thin black polyimide films prepared in each of Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated for tensile properties, i.e., tensile strength, elongation And the modulus of elasticity were measured. The results are shown in Table 2 below.

The first PI chain
(weight%) The second PI chain
(weight%) Carbon black
(weight%) Tensile Properties Tensile Strength (MPa) Shinto (%) Modulus of Elasticity (GPa) Example 1 92 3 5 200 33 3.7 Example 2 90 5 5 195 35 3.7 Example 3 85 10 5 190 37 3.6 Example 4 80 15 5 188 40 3.5 Comparative Example 1 95 0 5 200 30 3.8 Comparative Example 2 75 20 5 170 40 3.3 Comparative Example 3 65 30 5 160 45 3.2 Comparative Example 4 92 3 5 200 25 3.9

As shown in Tables 1 and 2, in the case of the ultra thin black polyimide films of Examples 1 to 4, the second polyimide chain imidized from soft dianhydride and soft diamine is contained in the range of 3 to 15 wt% It can be seen that the physical properties such as gloss, transmittance and tensile properties were not lowered as compared with Comparative Example 1 which did not contain the second polyimide chain, and that the content of the second polyimide chain in the content In the case of Comparative Examples 2 to 3 which are out of the range, it can be confirmed that the physical properties as described above are lowered than in Example 1. [

In addition, in Comparative Example 4 in which the first polyamic acid solution contained at least 80 mol% of soft dianhydride and soft diamine, it was confirmed that physical properties such as gloss, transmittance and tensile properties were lower than those of Example 1.

EXPERIMENTAL EXAMPLE 4 Evaluation of Resistance to Alkali

The ultra thin black polyimide film prepared in each of Examples 1 to 4, Comparative Examples 1 to 3 and Comparative Example 5 was subjected to a double-side corona treatment, and then a black polyimide film, Using a sheet (adhesive) and copper foil structure, a hot press is applied at a pressure of 50 kgf and a temperature of 160 ° C for 30 minutes to form an FCCL sample.

The FCCL cut in 4 * 10 cm was exposed to 10% NaOH solution at 55 ° C for 3 minutes, exposed to distemir (10% NaMnO ₄ + 4% NaOH) at 55 ° C for 5 minutes, The thickness of the film was measured, and the degree of change in thickness after exposure compared to the thickness before exposure to NaOH solution and dismear solution was expressed as a percentage, and the results are shown in Table 3 below.

The first PI chain
(weight%) The second PI chain
(weight%) Carbon black
(weight%) Alkali resistance index (%) Example 1 92 3 5  73 Example 2 90 5 5  75 Example 3 85 10 5  80 Example 4 80 15 5  85 Comparative Example 1 95 0 5 60 Comparative Example 2 75 20 5  88 Comparative Example 3 65 30 5  92 Comparative Example 5 92 3 5  65

As shown in Table 3, in the case of the ultra thin black polyimide films of Examples 1 to 4, the alkali resistance index was 70% or more, and the content of the second small amount of 3 to 15% It can be confirmed that when manufactured to contain a polyimide chain, the chemical resistance is remarkably superior to that of Comparative Example 1 which does not include the second polyimide chain.

In the case of Comparative Examples 2 and 3 in which the content of the second polyimide chain was outside the content range according to the present invention, it was confirmed that the alkali resistance index was 85% or more and the chemical resistance was excellent. In Tables 1 and 2 It can be confirmed that the properties of the ultra-thin black polyimide films of Comparative Examples 2 and 3 were lowered as compared with those of Example 1.

In addition, it was confirmed that the second polyamic acid solution of Comparative Example 5 containing less than 80 mol% of soft dianhydride and soft diamine was not excellent in chemical resistance as compared with Example 1.

FIG. 1 shows an external view of the FCCL produced by using the ultra-thin black polyimide film of Comparative Example 1 after exposure to alkali. FIG. 2 is a cross-sectional view of the ultra-thin black polyimide film of Example 1 Lt; RTI ID = 0.0 &gt; FCCL &lt; / RTI &gt;

Referring to FIGS. 1 and 2, it can be confirmed that the surface of the FCCL according to Comparative Example 1 is more damaged than the surface of the FCCL prepared from Example 1 having improved chemical resistance.

Experimental Example 5: Evaluation of storage stability

With respect to the second polyamic acid solution prepared in Example 5 and the second polyamic acid solution prepared in Comparative Example 6 and Comparative Example 7, a change with time in viscosity over 30 days at room temperature was measured with a Brookfield The viscosity of the second polyamic acid solution was measured using a viscometer. The viscosity of the second polyamic acid solution after storage for 30 days was compared with that of the second polyamic acid solution. The results are shown in Table 4 below.

Storage stability (%) Example 5 85 Comparative Example 6 60 Comparative Example 7 65

As can be seen in Table 5, in the case of the second polyamic acid of Example 5 in which the end blocker was added during the polymerization, Comparative Example 6, in which the end blocker was not used during the polymerization, and the end blocker, It was confirmed that the storage stability was superior to that of the second polyamic acid of Comparative Example 7.

Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

Claims (20)

A process for producing a polyimide film obtained by mixing and imidizing two or more different polyamic acids,
(a) polymerizing a first polyamic acid having excellent rigidity from a first dianhydride and a first diamine;
(b) polymerizing a second polyamic acid having excellent chemical resistance from an end-capping agent, a second dianhydride and a second diamine;
(c) preparing carbon black having an average particle diameter of 0.1 to 5 탆 by using a milling machine and preparing a black tank liquid containing the carbon black;
(d) mixing the second polyamic acid and the black tank liquid to prepare a mixed solution; And
(e) mixing and dispersing the mixed solution in the first polyamic acid, forming a film on the support, and heat treating the film by imidization,
A method for producing an ultra-thin black polyimide film having an alkali resistance index of 70% or more evaluated on the basis of the thickness of a polyimide film. The method according to claim 1,
Wherein the first polyamic acid and the second polyamic acid form a first polyimide chain and a second polyimide chain through an imidization step, respectively. 3. The method of claim 2,
Wherein the first polyamic acid and the second polyamic acid form a structure in which at least a part of the first polyimide chain and the second polyimide chain are cross-linked to each other through an imidation step. The method according to claim 1,
With respect to the total weight of the polyimide film,
80 to 93% by weight of a first polyimide chain excellent in rigidity,
A second polyimide chain having an excellent chemical resistance of 2 to 15% by weight, and
And carbon black having an average particle size of 0.1 to 5 占 퐉 in an amount of 3 to 10% by weight,
Wherein the thickness of the film is 8.0 占 퐉 or less. The method according to claim 1,
Wherein the first dianhydride and the second dianhydride are each independently selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA), and Benzophenone tetracarboxylic dianhydride (BTDA), and at least one selected from the group consisting of benzophenone tetracarboxylic dianhydride (BTDA)
The first diamines and the second diamines are independently selected from the group consisting of 1,4-phenylenediamine (PPD), 4,4'-oxydianiline (ODA), 3,4'-oxydianiline, (4-aminophenoxy) phenyl] propane (BAPP), 4,4'-methylene dianiline (MDA), and 1,3-bis (4-aminophenoxy) benzene TPE-R). &Lt; / RTI &gt; The method according to claim 1,
Wherein the first dianhydride does not contain a soft dianhydride or contains less than 10 mol% of a dianhydride based on the total dianhydride monomer constituting the first polyamic acid,
Wherein the first diamines do not contain soft diamines or contain less than 80 mol% of soft diamines relative to the total of the diamines monomers constituting the first polyamic acid,
Wherein the soft dianhydride and the soft diamine each comprise two or more benzene rings in the molecular structure. The method according to claim 1,
Wherein the second dianhydride includes at least 80 mol% of a dianhydride based on the entire dianhydride monomer constituting the second polyamic acid,
Wherein the second diamines include at least 80 mol% of a soft diamine based on the entire diamines monomers constituting the second polyamic acid,
Wherein the soft dianhydride and the soft diamine each comprise two or more benzene rings in the molecular structure. 8. The method according to claim 6 or 7,
Wherein the flexible dianhydride is at least one selected from the group consisting of biphenyl tetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA) A method for producing a black polyimide film. 8. The method according to claim 6 or 7,
The soft diamines include 4,4'-oxydianiline (ODA), (4-aminophenoxy) phenyl] propane (BAPP), 4,4'-methylene dianiline (MDA) and 1,3-bis 4-aminophenoxy) benzene (TPE-R). &Lt; / RTI &gt; The method according to claim 1,
Wherein the second polyamic acid has a polymerization viscosity ranging from 100,000 to 150,000 cp at a solid content of 15%. The method according to claim 1,
Wherein the second polyamic acid has a viscosity retention ratio of 80% or more at room temperature for 30 days. The method according to claim 1,
Wherein the mixed liquid has a viscosity ranging from 50 to 1000 cp. The method according to claim 1,
Wherein the end blocker is contained in an amount ranging from 0.05 to 1% by weight based on the weight of the solid content of the second polyamic acid. The method according to claim 1,
Wherein the end blocker is at least one selected from the group consisting of phthalic anhydride (PA), maleic anhydride (MA), and glutaric anhydride (GA). An ultra-thin black polyimide film produced by the process according to claim 1. A polyimide film obtained by mixing and imidizing two or more different polyamic acids,
Based on the total weight of the polyimide film, a first polyimide chain having 80 to 93 wt%
A second polyimide chain having an excellent chemical resistance of 3 to 15% by weight, and
And carbon black having an average particle size of 0.1 to 5 占 퐉 in an amount of 3 to 10% by weight,
Wherein the second polyimide chain is derived from a second polyamic acid having an amine end blocked by an end blocker and having excellent chemical resistance,
An ultra-thin black polyimide film having an alkali resistance index of 70% or more, which is evaluated based on the thickness of the polyimide film. 17. The method of claim 16,
Wherein the film has a thickness of 3 to 7.5 占 퐉. 17. The method of claim 16,
Wherein the film has a light transmittance of 10% or less in a visible light region and a gloss of 10 to 50%. A coverlay comprising the ultra thin black polyimide film according to claim 16. An electronic device comprising a coverlay according to claim 19.

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