KR20210085963A - Polyimide based film - Google Patents

Abstract

The present invention relates to a polyimide-based film, wherein a spread rate of a film stored in a roll form after the production of the film is improved, and in particular, there is an effect of providing an improved spread rate even for the film having a relatively thick film thickness. The present invention includes a copolymer of a diamine compound, a dianhydride compound, and a dicarbonyl compound.

Description

Polyimide based film

The present invention relates to a polyimide-based film and a polyimide-based film body including the same.

Recently, as one of the next-generation displays, flexible electronic devices such as flexible OLED, flexible optoelectronic devices, lightweight displays, flexible encapsulants, Color EPD, Plastic LCD, TSP, OPV, etc. have attracted attention as electronic devices that can be bent or bent as one of the next-generation displays. have. In particular, as devices such as foldable or rollable devices that can be bent or rolled are being developed, a flexible type display can be realized and a new type of flexible substrate that can protect the underlying device is required. Do.

As such a flexible display substrate material, various high-hardness plastic substrates are being considered as candidates, and among them, a transparent polyimide-based film capable of realizing high hardness in a thin thickness is being considered as a particularly important candidate for a cover substrate. However, in the case of thinning the polyimide-based film in consideration of the thin-film mobile application, if the polyimide-based film body provided with a coating layer on the polyimide-based film is rolled up and stored in the form of a roll, air may be included in the drying process or the films may stick together. It was confirmed that shape defects occurred during use.

Japanese Patent Laid-Open No. JP2019-77191

It is an object of the present invention to provide a polyimide-based film having a specific spreading ratio value, which is stored in a roll form after preparation of the polyimide-based film, and suppressed from deformation of the film even after being unfolded for use and having excellent product processability.

Another object of the present invention is to provide a method for manufacturing a polyimide-based film in which deformation is suppressed when stored in a roll form and unfolded for use by controlling curing conditions.

Another object of the present invention is to provide an electronic component including a polyimide-based film, which has a specific spreading rate and provides excellent product processability.

A polyimide-based film according to an embodiment of the present invention,

A polyimide-based film containing a copolymer of a diamine compound, a dianhydride compound, and a dicarbonyl compound, and having a size of 100 mm x 100 mm, is rolled so that the inner diameter from the center to the end is 6 mm in the form of a polyimide-based film roll 3 After storage for one day, the roll shape is unwrapped and then placed as shown in FIG. 1 , and the value of the spread ratio according to Equation 1 below may be 0.1 to 4.0.

[Equation 1]

Spread Ratio = {(H2-H1) x (A2-T2)} / {D x (A1-T1)}

(In Equation 1, H1 and H2 are the average values (unit mm) of the heights measured from the ground to the four vertices after unrolling the roll shape and leaving the first or second standing, respectively, and A1 and A2 are 4 of the film When the vertices are a1, a2, b1, b2, the average value of the hypothetical shortest distance between a1 and a2 and the hypothetical shortest distance between b1 and b2 measured after unrolling the roll shape and leaving the first or second standing, respectively (unit mm), T1 and T2 are the first or second standing time (unit min), respectively, and D is the thickness of the film (unit: um).

The polyimide-based film may have a spreadability value of 0.5 to 3.5.

The polyimide-based film may have a spreadability value of 0.6 to 3.1.

When the thickness of the polyimide-based film is 10 to 150 μm, the average value of the height measured from the ground to four vertices from the ground to 35 or less may be satisfied after unrolling the roll shape and positioning it as shown in FIG. 1 for 1 minute.

When the thickness of the polyimide-based film is 10 to 150 μm, when the four vertices of the film are a1, a2, b1, b2, the virtual between a1 and a2 measured after unrolling the roll shape and leaving it for 1 minute The average value of the shortest distance between b1 and b2 may satisfy 18 or more.

When the thickness of the polyimide-based film is 10 to 150 μm, the average value of the height measured from the ground to the four vertices from the ground to 34 or less may be satisfied after unrolling the roll shape and positioning it as shown in FIG. 1 for 30 minutes.

When the thickness of the polyimide-based film is 10-150 μm, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 30 minutes, and the imaginary shortest distance between a1 and a2 The average value of the distance and the virtual shortest distance between b1 and b2 may satisfy 33 or more.

When the thickness of the polyimide-based film is 20 to 55 μm, the average value of the height measured from the ground to the four vertices from the ground to 32 or less may be satisfied after unrolling the roll shape, placing it as shown in FIG. 1 , and allowing it to stand for 1 minute.

When the thickness of the polyimide-based film is 20 to 55 μm, the average value of the height measured from the ground to four vertices from the ground to 28 or less may be satisfied after unrolling the roll shape, placing it as shown in FIG. 1 and leaving it for 30 minutes.

When the thickness of the polyimide-based film is 20 to 55 μm, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 1 minute, and virtual between a1 and a2 among the vertices The average value of the shortest distance between b1 and b2 may satisfy 55 or more.

When the thickness of the polyimide-based film is 20 to 55 μm, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 30 minutes, and the imaginary shortest distance between a1 and a2 The average value of the distance and the virtual shortest distance between b1 and b2 may satisfy 71 or more.

According to another aspect of the present invention,

preparing a liquid resin composition using a diamine compound, a dianhydride compound, and a dicarbonyl compound; using the liquid resin composition to prepare a film in a gel state; drying the film in the gel state at 50 to 150° C. for 2 to 30 minutes; And After the drying step, stretching the film in the gel state and curing at a temperature of 120 to 320 ° C. at a wind speed of 1.0 to 3.0 m / s for 1 minute to 2 hours; Preparation of a polyimide-based film comprising a provide a way

The liquid resin composition has a viscosity of 1000 to 250,000 cPs.

The preparing of the liquid resin composition includes preparing a polymer solution by reacting the monomer components in the presence of a first solvent, adding a second solvent to the polymer solution, filtering and drying to prepare a polymer solid and dissolving the polymer solid in a third solvent.

It is preferable that the stretching reflects the shrinkage ratio calculated by the following formula (2).

[Equation 2]

Shrinkage: {(length before measurement - length after measurement)/length before measurement} x 100

The shrinkage rate is within the range of 2% or less when TMA measurement is performed from room temperature to 280°C.

Another aspect of the present invention provides a polyimide-based film prepared by the above manufacturing method.

A polyimide-based film body according to another aspect of the present invention,

As a polyimide-based film body comprising the above-described polyimide-based film,

On one side or both sides of the polyimide-based film, a primer film, a hardness-reinforced film, a flexible film, a folding film, a flexural strength reinforcement film, a visibility improvement film, a barrier film, an antibacterial film, a water-repellent film, an anti-fingerprint film, a reflection It will include at least one selected from an anti-aging film and a film providing a smooth touch.

A window member according to another aspect of the present invention,

glass cover; and

A window member comprising a polyimide-based film provided on at least one surface of the glass cover,

The polyimide-based film is the above-described polyimide-based film.

A window member according to another aspect of the present invention,

glass cover; and

A window member comprising a polyimide-based film body provided on at least one surface of the glass cover,

The polyimide-based film body is the polyimide-based film body described above.

According to an embodiment of the present invention, a polyimide-based film having a specific spreadability value may be manufactured by controlling curing conditions in the manufacturing process of the polyimide-based film. The polyimide-based film according to an embodiment of the present invention may have a specific spread value and prevent deformation, thereby providing excellent product processability.

The polyimide-based film manufactured according to an embodiment of the present invention, having a specific spread value and excellent product processability, has excellent deformation suppression effect even when the thickness of the film is relatively thick.

1 is a view schematically showing a film form in which a polyimide-based film is stored in a roll form and then unrolled and then spread rate is measured according to an embodiment of the present invention.
2 is a polyimide-based film stored for 3 days in the form of a roll, and then shows the deformation height and the degree of expansion according to the thickness and elapsed time of the film after unpacking, (a) Figure 1 for a film with a thickness of 20 ~ 55um It shows the deformed form when left for minutes (left) and left for 30 minutes (right), and (b) the figure shows deformation when left for 1 minute (left) and left for 30 minutes (right) for films with a thickness greater than 55um and less than or equal to 100um. indicates the formed form.

Before describing the present invention in detail, it is to be understood that the terminology used herein is for the purpose of describing specific embodiments only, and does not limit the scope of the present invention, which is limited only by the appended claims.

All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art, unless otherwise stated.

Throughout this specification and claims, unless otherwise stated, the term comprise, comprises, comprising means including the referenced object or step or set of objects or groups of steps, and any It is not used in the sense of excluding other objects or steps, groups of objects or groups of steps.

On the other hand, various embodiments of the present invention may be combined with any other embodiments unless clearly indicated to the contrary. In particular, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous.

In this specification, the term "film" generally refers to a thin plate-like member, but also includes the concept of a film formed by liquid coating.

In this specification, the term "film body" is intended to include a structure including one or more layers of the above-described film or a laminated structure, and furthermore, a device having such a structure.

In the present specification, the term "polyimide-based" is intended to collectively include polyimide, polyamide, and polyimide-based.

In addition, the concept of “locating on” in the present specification should be understood as being positioned “on” not only directly on it, but also on other members intervening therebetween.

For example, the polyimide-based film according to an embodiment of the present invention includes a copolymer of a diamine compound, a dianhydride compound, and a dicarbonyl compound, and a polyimide-based film having a size of 100 mm x 100 mm is formed from the center to the ends. After being rolled so that the inner diameter of the film becomes 6 mm and stored in the form of a polyimide-based film roll for 3 days, the roll form is unwrapped and placed as shown in FIG. 1, and the value of the expansion ratio according to the following formula 1 is within the range of 0.1 to 4.0. to have stability.

[Equation 1]

Spread Ratio = {(H2-H1) x (A2-T2)} / {D x (A1-T1)}

(In Equation 1, H1 and H2 are the average values (unit mm) of the heights measured from the ground to the four vertices after unrolling the roll shape and leaving the first or second standing, respectively, and A1 and A2 are 4 of the film When the vertices are a1, a2, b1, b2, the average value of the hypothetical shortest distance between a1 and a2 and the hypothetical shortest distance between b1 and b2 measured after unrolling the roll shape and leaving the first or second standing, respectively (unit mm), T1 and T2 are the first or second standing time (unit min), respectively, and D is the thickness of the film (unit: um).

1 is a view schematically showing the shape of a film in which a polyimide-based film is stored in a roll form and then unrolled and then the spreading rate is measured according to an embodiment of the present invention.

Referring to FIG. 1, when the four vertices of the film, which are stored in the roll form and then unpacked and positioned in the form shown in FIG. 1, are a1, a2, b1, b2, a virtual straight line length connecting a1 and a2. And, the virtual straight line length connecting b1 and b2 corresponds to a value that changes as the film gradually unwinds over time, respectively. At this time, the straight line length connecting a1 and b1 and the straight line length connecting a2 and b2 indicates a fixed value (ie, 100 mm for a film of size 100 mm x 100 mm) regardless of the film unwinding.

As a specific example, when the thickness of the polyimide-based film is 10 to 150 μm, the average value of the height measured from the ground to the four vertices from the ground to the four vertices is 35 or less, after unrolling the roll shape, placing it as shown in FIG. can

When the thickness of the polyimide-based film is 10 to 150 μm, when the four vertices of the film are a1, a2, b1, b2, the virtual between a1 and a2 measured after unrolling the roll shape and leaving it for 1 minute The average value of the shortest distance between b1 and b2 may satisfy 18 or more.

When the thickness of the polyimide-based film is 10 to 150 μm, the average value of the height measured from the ground to the four vertices from the ground to 34 or less may be satisfied after unrolling the roll shape and positioning it as shown in FIG. 1 for 30 minutes.

When the thickness of the polyimide-based film is 10-150 μm, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 30 minutes, and the imaginary shortest distance between a1 and a2 The average value of the distance and the virtual shortest distance between b1 and b2 may satisfy 33 or more.

When the thickness of the polyimide-based film is 20 to 55 μm, the average value of the height measured from the ground to the four vertices from the ground to 32 or less may be satisfied after unrolling the roll shape, placing it as shown in FIG. 1 , and allowing it to stand for 1 minute.

When the thickness of the polyimide-based film is 20 to 55 μm, the average value of the height measured from the ground to four vertices from the ground to 28 or less may be satisfied after unrolling the roll shape, placing it as shown in FIG. 1 and leaving it for 30 minutes.

When the thickness of the polyimide-based film is 20 to 55 μm, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 1 minute, and virtual between a1 and a2 among the vertices The average value of the shortest distance between b1 and b2 may satisfy 55 or more.

When the thickness of the polyimide-based film is 20 to 55 μm, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 30 minutes, and the imaginary shortest distance between a1 and a2 The average value of the distance and the virtual shortest distance between b1 and b2 may satisfy 71 or more.

According to an embodiment of the present invention, the polyimide-based film may have an spreadability value of 5.0 or less, 0.1 to 4.0, 0.5 to 3.5, or 0.6 to 3.1.

The lower the value of the spread ratio of the polyimide-based film, the greater the unfolding change and the less the degree of deformation, the better the workability (also referred to as runability) of the product.

According to an embodiment of the present invention, the spread rate value can be calculated by the unfolding height and the unfolding degree measured after the first standing time after unrolling the roll shape, and the unfolding height and the unfolding degree measured after the second standing time, and , as a specific example, the value of the spread ratio calculated according to Equation 1 described above may be referred to as a value obtained by quantifying the change in deformation after the polyimide-based film is unfolded.

A small value of the spread ratio of the polyimide-based film may be interpreted as a relatively thick polyimide-based film or a long standing time. A relatively thick film thickness or a long standing time may be interpreted as a small amount of deformation after unfolding the film, and a specific example can be found in FIG. 2 .

2 is a polyimide-based film stored for 3 days in the form of a roll, and then shows the deformation height and the degree of expansion according to the thickness and elapsed time of the film after unpacking, (a) Figure 1 for a film with a thickness of 20 ~ 55um It shows the deformed form when left for minutes (left) and left for 30 minutes (right), and (b) the figure shows deformation when left for 1 minute (left) and left for 30 minutes (right) for films with a thickness greater than 55um and less than or equal to 100um. indicates the formed form.

First, referring to FIG. 2(a), which measures a relatively thin film with a thickness of 20 to 55 μm of a polyimide-based film, in the case of unwinding the roll, it is placed as shown in FIG. 1 and left for 1 minute for the first standing time It can be seen that there is a significant difference in both the height and the degree of unfolding in the drawing on the right, where it was left for 30 minutes for the second leaving time, compared to the left drawing measured with

As an example, after releasing the roll shape, it is placed as shown in FIG. 1, left for 1 minute, and the average value of the height measured from the ground to the four vertices satisfies 32 or less, and after releasing the roll shape, it is positioned as shown in FIG. 1 30 The average value of the height measured from the ground to the four vertices after leaving it for a minute can satisfy 28 or less.

For example, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 1 minute, and among the vertices, the imaginary shortest distance between a1 and a2 and the imaginary shortest distance between b1 and b2 may satisfy an average value of 20 or less.

For example, when the four vertices of the film are a1, a2, b1, b2, the average value of the imaginary shortest distance between a1 and a2 and the imaginary shortest distance between b1 and b2 after unrolling the roll shape is left for 30 minutes. This 35 or less can be satisfied.

On the other hand, referring to FIG. 2(b), which measures a relatively thick film with a thickness of more than 55um and 100um or less of the polyimide-based film, the roll shape is unwrapped and then positioned as shown in FIG. 1 and left for 1 minute as the first standing time It can be seen that there is almost no difference in height in the measured right figure after leaving it for 30 minutes as the second leaving time compared to the measured left figure, and the degree of unfolding also does not show a significant difference compared to FIG. 2(a).

As an example, after releasing the roll shape, it is placed as shown in FIG. 1, left for 1 minute, and the average value of the height measured from the ground to the four vertices satisfies 35 or less, and after releasing the roll shape, it is positioned as shown in FIG. 1 30 The average value of the height measured from the ground to the four vertices after leaving it for a minute can satisfy 34 or less.

For example, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 1 minute, and among the vertices, the imaginary shortest distance between a1 and a2 and the imaginary shortest distance between b1 and b2 may satisfy an average value of 18 or more.

For example, when the four vertices of the film are a1, a2, b1, b2, the average value of the imaginary shortest distance between a1 and a2 and the imaginary shortest distance between b1 and b2 after unrolling the roll shape is left for 30 minutes. 33 or more can be satisfied.

Meanwhile, in the present invention, the polyimide-based film includes (i) diamine and dianhydride (ii) diamine, dianhydride and aromatic dicarbonyl compound, (iii) diamine, dianhydride and dianhydride or (iv) diamine , dianhydride, dianhydride, and is formed by copolymerization and imidization with any one combination of a combination of an aromatic dicarbonyl compound, and at this time, the sum of the remaining monomers with respect to the diamine forms an equivalent ratio of 1:1 with the diamine . Among the above combinations, it is preferable to add dianhydride to cap the ends of the polyimide molecular chain, but the present invention is not necessarily limited thereto.

The dianhydride that can be used in the present invention is 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), 4- (2,5-dioxotetrahydrofuran-3- yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride (TDA), pyromellitic acid dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, PMDA), benzophenone tetracarboxylic dianhydride (BTDA), biphenyl tetracarboxylic dianhydride (BPDA), biscarboxyphenyl dimethyl silane dianhydride (SiDA), oxydiphthalic dianhydride Ride (ODPA), bis dicarboxyphenoxy diphenyl sulfide dianhydride (BDSDA), sulfonyl diphthalic dianhydride (SO ₂ DPA), cyclobutane tetracarboxylic dianhydride (CBDA), isopropylidene It may include alone or two or more selected from phenoxy bis phthalic dianhydride (6HDBA). It is not limited thereto.

In addition, the diamine that can be used in the present invention is oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline ( mMDA), bistrifluoromethyl benzidine (TFDB), cyclohexanediamine (13CHD, 14CHD), bisaminohydroxyphenyl hexafluoropropane (DBOH), bisaminophenoxybenzene (133APB, 134APB, 144APB), bisamino Phenyl hexafluoropropane (33-6F, 44-6F), bisaminophenylsulfone (4DDS, 3DDS), bisaminophenoxyphenylhexafluoropropane (4BDAF), bisaminophenoxyphenylpropane (6HMDA), bisamino It may include alone or two or more selected from phenoxy diphenyl sulfone (DBSDA) and the like, but is not limited thereto.

In addition, the dianhydride that can be used in the present invention is a bicyclo heptene dicarboxylic dianhydride (Nadic anhydride), anthracenylethynyl phthalic dianhydride (4-(9-anthracenyl ethynyl)phthalic anhydride), a Damantanecarbonyl chloride (1-Adamantanecarbonyl chloride), adamantanedicarbonyl dichloride (1,3-Adamantanedicarbonyl dichloride), norbornene carbonyl chloride (5-Norbonene-2-carbonyl chloride), norbornene dicarbonyl chloride 5 -Norbonene-2、3-dicarbonyl chloride) and cyclopentane carbonyl chloride (cyclopentane chloride), etc. may be included alone or two or more selected from, but is not limited thereto.

In addition, when the polyimide of the present invention is a polyamide-imide including an amide structure, an aromatic dicarbonyl compound may be added as a monomer. In this case, the usable aromatic dicarbonyl compound is terephthaloyl dichloride. (p-Terephthaloyl chloride), terephthalic acid (Terephthalic acid), iso-phthaloyl dichloride (Iso-phthaloyl dichloirde), 4,4'-biphenyl dicarbonyl chloride (4,4'-biphenyldicarbonyl chloride), etc. alone or There may be two or more types, but is not limited thereto.

The process of manufacturing the polyimide-based film in a roll-to-roll method using the above monomers is not particularly limited, but an example of the method for manufacturing in the present invention will be described as follows.

가 바람직하고, 반응시간은 2~48시간이 바람직하다. 또한 반응시 아르곤이나 질소 등의 불활성 분위기인 것이 보다 바람직하다.A monomer selected from among the above-mentioned monomers is dissolved in the first solvent and then subjected to a polymerization reaction to first prepare a polyamic acid solution (polyimide or a precursor of polyimide-amide). At this time, the reaction conditions are not particularly limited, but the reaction temperature is -20 to 80

is preferred, and the reaction time is preferably 2 to 48 hours. In addition, it is more preferable that the reaction is in an inert atmosphere such as argon or nitrogen.

In the case of adding dianhydride among the monomers, the molecular weight is affected by the amount of dianhydride added during the reaction. In order not to reduce the intrinsic physical properties of the polyimide, 10 mol% or less based on the total mole of dianhydride and dianhydride , Preferably, it may be added in an amount of 5 mol% or less. When a large amount exceeding 10 mol% is used, the optical properties are reduced as the yellowness increases and the transmittance decreases as the molecular weight is lowered. Instead, crosslinking occurs as the dianhydride content increases, so improvement of thermal properties can be expected. However, a large amount of crosslinking disturbs the arrangement of the polymer chains, and thus the surface hardness may be reduced.

In addition, if you want to obtain a polyimide-based film having a polyamide-imide structure, the molecular weight may vary depending on the amount of the aromatic dicarbonyl compound added in the monomer. It is preferable to add 10 mol% or more, 80 mol% or less, preferably 30 mol% or more, 70 mol% or less to the total moles of the aromatic dicarbonyl compound component. When a large amount exceeding 80 mol% is used, the optical properties are reduced such that yellowness is increased and transmittance is lowered, and a gel is generated in the polyamic acid solution, making it difficult to obtain a film during film formation. In addition, when used in an amount of 10 mol% or less, optical properties are increased, but thermal properties such as a decrease in thermal expansion coefficient may also occur.

The solvent for the polymerization reaction of the monomers is not particularly limited as long as it is a solvent that dissolves the polyamic acid. One selected from m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), acetone, and ethyl acetate as a known reaction solvent Use more polar solvents. In addition, a low-boiling-point solution such as tetrahydrofuran (THF), chloroform, or a low-absorption solvent such as γ-butyrolactone may be used.

The content of the solvent is not particularly limited, but in order to obtain an appropriate molecular weight and viscosity of the polyamic acid solution, the content of the first solvent is preferably 50 to 95% by weight of the total polyamic acid solution, more preferably 70 to 90% by weight % is more preferable.

In this way, a polyimide-based film can be prepared by polymerizing the polyamic acid solution, imidizing it at a high temperature and heat-treating it to form a film. In this case, the prepared polyimide-based resin preferably has a glass transition temperature of 200 to 400° C. in consideration of thermal stability.

As a method for producing a polyimide-based film from a polyamic acid solution, there is a thermal imidization method, a chemical imidization method, or a method of using a thermal imidization method and a chemical imidization method in combination.

-피콜린, 피리딘 등의 3급 아민류 등으로 대표되는 이미드화 촉매를 투입하는 방법이다. 열이미드화법 또는 열이미드화법과 화학이미드화법을 병용하는 경우 폴리아믹산 용액의 가열 조건은 폴리아믹산 용액의 종류, 제조되는 폴리이미드계 필름의 두께 등에 의하여 변동될 수 있다.The chemical imidization method is a polyamic acid solution with a dehydrating agent represented by acid anhydride such as acetic anhydride, isoquinoline,

-This is a method of introducing an imidization catalyst represented by tertiary amines such as picoline and pyridine. When the thermal imidization method or the thermal imidization method and the chemical imidization method are used in combination, the heating conditions of the polyamic acid solution may vary depending on the type of the polyamic acid solution and the thickness of the polyimide-based film to be prepared.

More specifically, a production example of a polyimide-based film in the case of using the thermal imidization method and the chemical imidization method in combination, a dehydrating agent and an imidization catalyst are added to a polyamic acid solution, cast on a support, and then cast at 80 to 200 ° C. , preferably by heating at 100 to 180 ° C. to activate a dehydrating agent and imidization catalyst to partially harden and dry the polyamic acid film in a gel state by peeling it from a support, and fixing the gel film to a support and heat-treating it A polyimide-based film can be obtained. The gel film can be fixed using a pin-type frame or a clip-type frame. A glass plate, an aluminum foil, a circulation stainless belt, a stainless drum, etc. may be used as the support body.

Meanwhile, in the present invention, a polyimide-based film may be prepared from the obtained polyamic acid solution as follows. That is, after imidizing the obtained polyamic acid solution, the imidized solution is put into a second solvent, precipitated, filtered, and dried to obtain a polyimide-based resin solid content, and then the obtained polyimide-based resin solid content is reconstituted. It is dissolved in the first solvent, cast on a support, and heated for 1 minute to 8 hours while gradually raising the temperature in the temperature range of 40 to 400° C. as described above to obtain a gel-like polyimide-based film.

The first solvent may be the same solvent as the solvent used for polymerization of the polyamic acid solution, and the second solvent is used with a lower polarity than the first solvent in order to obtain a solid content of the polyimide-based resin, specifically water , alcohols, ethers, and ketones may be at least one selected from the group consisting of ketones.

At this time, the content of the second solvent is not particularly limited, but is preferably 5 to 20 parts by weight based on the weight of the polyamic acid solution.

The conditions for drying after filtering the obtained polyimide-based resin solid content are preferably 50 to 150° C. and 2 to 30 minutes for the time, in consideration of the boiling point of the second solvent.

In addition, when the polyimide-based film is manufactured, a filler may be added during the preparation of the polyamic acid solution for the purpose of improving various properties such as slidability, thermal conductivity, conductivity, and corna resistance of the film. The filler is not particularly limited, but preferred embodiments include silica, titanium oxide, layered silica, carbon nabotube, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and undo.

The particle diameter of the filler may vary depending on the characteristics of the film to be modified and the type of filler to be added, and is not particularly limited, but in general, the average particle diameter is preferably 0.001 to 50 μm, and 0.005 to 25 μm. More preferably, it is good that it is 0.01-10 micrometers more preferably. In this case, the effect of modifying the polyimide-based film is easily exhibited, and good surface properties, conductivity and mechanical properties can be obtained in the polyimide-based film.

In addition, the amount of the filler added may vary depending on the characteristics of the film to be modified and the type of filler to be added, and is not particularly limited. In general, the content of the filler is preferably 0.001 to 20 parts by weight, more preferably 0.01 to 10 parts by weight, based on 100 parts by weight of the polyamic acid solution, in order to exhibit the properties to be modified without interfering with the bonding structure of the polymer resin. It's good to be Mrs.

preparing a liquid resin composition using a diamine compound, a dianhydride compound, and a dicarbonyl compound; using the liquid resin composition to prepare a film in a gel state; drying the film in the gel state at 50 to 150° C. for 2 to 30 minutes; And After the drying step, stretching the film in the gel state and curing at a temperature of 120 to 320 ° C. at a wind speed of 1.0 to 3.0 m / s for 1 minute to 2 hours; Preparation of a polyimide-based film comprising a provide a way

According to an embodiment of the present invention, drying is performed to remove the solvent contained in the film in a gel state, for example, it is dried at 50 to 150 ℃ for 2 to 30 minutes.

In general, since a solvent having a high boiling point is used in the manufacturing process of the liquid resin composition, it can be considered that a strong wind speed must be applied to the cast gel film in order to efficiently remove the solvent.

In general, the drying efficiency increases as the temperature increases. On the other hand, when the drying temperature increases and the drying temperature approaches the boiling point of the solvent, air bubbles may be generated on the surface of the polyimide-based film due to sudden volatilization of the solvent, and bending may occur. the surface uniformity of

Therefore, in the drying step, drying is carried out at a temperature of 50° C. in order to secure drying efficiency, and drying is performed at a temperature of 150° C. or less to prevent sudden volatilization of the solvent. In order to improve drying efficiency, drying may be performed in a temperature range of 70 to 150°C.

According to an embodiment of the present invention, after drying, the residual solvent content ratio of the uncured polyimide film may be adjusted to 50% by weight or less. More specifically, after drying, the residual solvent content ratio of the uncured polyimide film may be adjusted to 40 wt% or less.

According to an embodiment of the present invention, after the drying step, the step of stretching the gel state film may be carried out. Then, the step of curing the film in the gel state at 120 to 320 ℃ at a wind speed of 1.0 to 3.0 m/s for 1 minute to 2 hours may be carried out. When the wind speed of curing is less than 1.0 m/s, or when the temperature is less than 120° C., the speed of curing may be excessively reduced. When the curing rate is excessively reduced, the efficiency of the process is reduced, and physical properties of the polyimide-based film may be changed due to an increase in drying time.

The wind speed in the curing step may be adjusted, for example, in the range of 1.5 to 3.0 m/s, and more specifically, the wind speed in the curing step may be adjusted in the range of 1.6 to 3.0 m/s.

According to an embodiment of the present invention, the film spread rate (also referred to as strain rate) may be affected depending on the temperature applied in the curing step. The shrinkage and expansion behavior of the gel film according to the curing temperature was measured through TMA.

TMA was measured in a nitrogen atmosphere while raising the temperature from room temperature to 350 °C at 10 °C/min using a TMAQ400 of TA Instrument. At this time, the shrinkage of the film was calculated from Equation 2 below.

[Equation 2]

Shrinkage: {(length before measurement - length after measurement)/length before measurement} x 100

For reference, the shrinkage value calculated according to Equation 2 was calculated to be within 2% at 280°C, which is the highest curing temperature condition.

According to an embodiment of the present invention, when the shrinkage result and curing conditions according to Equation 2 are reflected, a film having an excellent spreading rate (strain rate) can be obtained.

Even if you do not adjust the width of the tenter during curing, there is an effect of stretching as much as the shrinkage, but if you use a length-adjustable tenter and stretch it within 2%, for example, up to 2% in consideration of the shrinkage, the expansion rate (strain) will increase without breaking the tenter. It is preferable to obtain an excellent film.

On the other hand, if the width is reduced by that much in consideration of the shrinkage rate according to Equation 2, the film spreading rate (strain rate) is poor. As a result, it is possible to obtain a film with excellent spreading rate (strain rate) by optimal stretching in consideration of the shrinkage force of the film.

Accordingly, the film length in tenter curing can be adjusted in the range of 2% or less, preferably greater than 0% and 2% or less.

In the curing step, for example, the film in the gel state may be heat-treated at a temperature of 120 to 320 ℃ at a wind speed of 1.0 to 3.0 m / s for 10 minutes to 2 hours.

The curing step may be performed on a support or a separate heat treatment support. For example, a pin-type frame or a clip-type frame may be used to support the film in a gel state.

According to an embodiment of the present invention, the content of the volatile component remaining in the polyimide-based film after curing may be adjusted to be 5% by weight or less.

According to an embodiment of the present invention, heat treatment may be performed in a state in which a constant tension is applied to the cured polyimide-based film. Residual stress inside the polyimide-based film may be removed by heat treatment.

When curing is performed, the coefficient of thermal expansion of the polyimide-based film may be reduced. For example, a residual stress to shrink in the polyimide-based film may be generated by curing, and thermal expansion may be reduced, and a hysteresis of the thermal expansion coefficient may be reduced in the polyimide-based film.

The liquid resin composition has a viscosity of 1000 to 250,000 cPs.

The preparing of the liquid resin composition includes preparing a polymer solution by reacting the monomer components in the presence of a first solvent, adding a second solvent to the polymer solution, filtering and drying to prepare a polymer solid and dissolving the polymer solid in a third solvent.

The film body according to an embodiment of the present invention is on one side or both sides of the polyimide-based film, a primer film, a hardness-reinforced film, a flexible film, a fold-back film, a flexural strength-reinforced film, a visibility improvement film, a barrier film, an antibacterial film It may include at least one selected from a film, a water-repellent film, an anti-fingerprint film, an anti-reflection film, and a film providing a smooth touch.

A window member according to another embodiment of the present invention includes a glass cover; and a polyimide-based film provided on at least one surface of the glass cover, wherein the polyimide-based film is the aforementioned polyimide-based film.

A window member according to another embodiment of the present invention includes a glass cover; and a polyimide-based film body provided on at least one surface of the glass cover, wherein the polyimide-based film body is the above-described polyimide-based film body window member.

Example

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention in more detail, and the present invention is not limited thereto. The amount of TPC used as a dicarbonyl compound presented as an example may be changed within an error range depending on the viscosity value.

In the following description, "%" and "part" indicating amounts are by weight unless otherwise specified. In addition, the operation described below was performed under the conditions of normal temperature and normal pressure, unless otherwise stated. A "specimen" means what cut out the film which concerns on the Example and the comparative example mentioned below to predetermined size.

<Preparation Example 1. Preparation of polyimide-based resin>

As a reactor, 832 g of N,N-dimethylacetamide (DMAc) was filled in a 1L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler while passing nitrogen, and then the temperature of the reactor was adjusted to 25℃. 64.046 g of bis trifluoromethyl benzidine (TFDB) was dissolved and the solution was maintained at 25°C. Here, 31.09 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 8.83 g of biphenyl tetracarboxylic dianhydride (BPDA) were added and stirred for a certain period of time. was dissolved and reacted. At this time, the temperature of the solution was maintained at 25 °C. Then, 20.302 g of terephthaloyl chloride (TPC) was added to obtain a polyamic acid solution having a solid concentration of 13% by weight.

25.6 g of pyridine and 33.1 g of acetic anhydride were added to the polyamic acid solution, stirred for 30 minutes, stirred at 70° C. for 1 hour, cooled to room temperature, precipitated with 20 L of methanol, and the precipitated solid was filtered and pulverized Then, it was dried at 100° C. under vacuum for 6 hours to obtain 111 g of solid powder polyimide-amide.

<Production Example 2>

100 g of natural amorphous silica particles (SEAHOSTAR, NIPPON SHOKUBAI) were heat treated at 800 ° C. for 2 hours, cooled to room temperature, and 400 g of hydrochloric acid and the heat treatment in a 0.5 L reactor equipped with a Teflon stirrer, nitrogen injection device, temperature controller and condenser attached to the reactor After filling 60 g of the amorphous silica particles, the temperature of the reactor was adjusted to 105° C., and the mixture was stirred under reflux for 1 hour. Thereafter, the amorphous silica particles were filtered, washed with distilled water, and dried in a vacuum oven at 80° C. for 12 hours to obtain 54 g of amorphous silica particles. 50 g of the dried amorphous silica particles and 150 ml of sodium hydroxide aqueous solution (10 wt %) were put into a reactor, maintained and stirred at 100 ° C. for 3 hours, refluxed, cooled at room temperature, washed with distilled water, and then in a vacuum oven at 80 ° C. for 12 hours During drying, 44 g of amorphous silica particles (average particle size: 0.1 μm) having OH groups bonded to the surface were prepared.

Example 1

100 g of polyamide-imide of the solid powder obtained in Preparation Example 1 was dissolved in 670 g of N,N-dimethylacetamide (DMAc) to obtain a 13wt% solution. The solution thus obtained was applied to a glass plate, cast to 200 μm, and dried with hot air at 120° C. for 20 minutes to obtain a gel film having a DMAc content of 14%.

To evaluate the product shrinkage, the shrinkage and expansion behavior of the gel film according to the curing temperature was measured under nitrogen at 10°C/min from room temperature to 350°C using TA Instrument's TMAQ400. At this time, the shrinkage rate of the gel film was obtained according to Equation 2 below, and the measured shrinkage value was calculated as 2% by raising the temperature from room temperature to 280°C (maximum curing temperature).

[Equation 2]

Shrinkage: {(length before measurement - length after measurement)/length before measurement} x 100

Then, the gel film was peeled off the glass plate and fixed on a tenter with adjustable length. At this time, the length of the tenter was 150mm x 150mm, and it was stretched to 153mm x 153mm by increasing the length by 2% of the aforementioned shrinkage.

After that, it was cured at a rate of 2.7 °C/min from 120 °C to 280 °C for 60 minutes to obtain a film having a thickness of 50 µm. The film was cut to a size of 100 mm x 100 mm and the strain was measured.

Example 2

100 g of polyamide-imide of the solid powder obtained in Preparation Example 1 was dissolved in 670 g of N,N-dimethylacetamide (DMAc) to obtain a 13wt% solution. The solution thus obtained was applied to a glass plate, cast to 300 μm, and dried with hot air at 120° C. for 20 minutes to obtain a gel film having a DMAc content of 14%.

The obtained gel film was peeled off from the glass plate and fixed on a tenter with adjustable length. At this time, the length of the tenter was 150mm x 150mm, and it was stretched to 153x153mm by increasing the length by 2% as described above.

Thereafter, it was cured from 120°C to 280°C at a rate of 2.7°C/min for 60 minutes to obtain a film having a thickness of 80 µm. The film was cut to a size of 100 mm x 100 mm and the strain was measured.

Example 3

A polyimide film was prepared in the same manner as in Example 1, but 0.05 g of amorphous silica particles having an OH group bonded to the surface prepared in Preparation Example 2 were added to 50 g of N,N-dimethylacetamide (DMAc), and the An amorphous silica particle dispersion (dispersion concentration: 0.1% by weight) was obtained by ultrasonication until N,N-dimethylacetamide (DMAc) became transparent.

Then, the amorphous silica particle dispersion obtained above and 100 g of the polyimide solid content of Preparation Example 1 were mixed with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler filled with 639 g of N,N-dimethylacetamide (DMAc) 1L A polyimide film was prepared in the same manner as in Example 2 (thickness 80 μm) by dissolving the mixture (solids concentration of 13wt%) while passing nitrogen through the reactor and stirring.

Example 4

As a transparent material layer, 25 parts by weight of nonyl acrylate, 10 parts by weight of 2-hydroxylethyl acrylate, 15 parts by weight of isobornyl acrylate, 15 parts by weight of hexanediol diacrylate and phosphine-based photoinitiator in 100 parts by weight of urethane acrylate 3 parts by weight was added and stirred at room temperature for 1 hour. Then, filtered and filtered to prepare a transparent material layer solution.

In addition, as a transparent adhesive layer, 5 parts by weight of nonyl acrylate, 5 parts by weight of 2-hydroxylethyl acrylate, 5 parts by weight of isobornyl acrylate, 3 parts by weight of hexanediol diacrylate for 100 parts by weight of 2-ethylhexyl acrylate , and 1 part by weight of a phosphine-based photoinitiator and stirred at room temperature for 1 hour. Then, it was filtered to prepare a transparent adhesive layer solution.

The transparent material layer solution and the transparent adhesive layer solution were applied to a thickness of 10 μm and 20 μm, respectively, on the polyimide-based film obtained in Example 1 using a co-extrusion T die (total thickness of 80 μm).

The applied multilayer liquid film was UV-cured to form a coating layer.

In this case, the size of the polyimide-based film was 150 mm x 150 mm, and the thickness was 80 μm. The film was cut to a size of 100 mm x 100 mm and the strain was measured.

Comparative Example 1

A Gel Film was prepared in the same manner as in Example 1 to obtain a Gel film having a DMAc content of 14%.

The obtained gel film was peeled from the glass plate and fixed on a tenter with adjustable length. At this time, the length of the tenter was 150 x 150 mm, reflecting the above-mentioned shrinkage, but the length was reduced by 2% to 147 mm x 147 mm. After that, it was cured at a rate of 2.7 °C/min from 120 °C to 280 °C for 60 minutes to obtain a film having a thickness of 50 µm. The film was cut to a size of 100 mm x 100 mm and the strain was measured.

Comparative Example 2

A gel film having a DMAc content of 14% was obtained by preparing a gel film in the same manner as in Example 2.

The obtained gel film was peeled off from the glass plate and fixed on a tenter with adjustable length. At this time, the length of the tenter was 150mm x 150mm, and the length was reduced by 2% to 147mm x 147mm. Thereafter, it was cured from 120°C to 280°C at a rate of 2.7°C/min for 60 minutes to obtain a film having a thickness of 80 µm. The film was cut to a size of 100 mm x 100 mm and the strain was measured.

For the polyimide-based films prepared in Examples and Comparative Examples The physical properties of Table 1 were measured, and the results are shown in Table 1.

(1) Measuring the thickness of the film

Using an Anritsu Electronic Micrometer, the thickness of the polyimide-based film was measured.

(2) optical transmittance

For the polyimide-based films prepared in Examples and Comparative Examples, average optical transmittance was measured in a wavelength range of 380 to 780 nm using a UV spectrometer (Cotica Minolta CM-3700d). The thickness of the polyimide-based film is shown in Table 1.

(3) Yellowness (Yellow Index, Y.I.)

The yellowness of the polyimide-based film was measured using a UV spectrometer (Cotica Minolta CM-3700d) according to ASTM E313 standard.

(4) Haze

It was measured three times using a hazemeter (Murakami Color Research Laboratory, HM-150) and the average value was measured.

thickness (um) permeability yellowness haze Example 1 50.0±2.0 89.0 2.8 0.3 Example 2 80.0±2.0 88.7 4.4 0.3 Example 3 80.0±2.0 89.1 4.1 0.4 Comparative Example 1 50.0±2.0 89.0 2.8 0.3 Comparative Example 2 80.0±2.0 88.7 4.4 0.3

In addition, the spreading ratio was calculated according to the following formula 1 and shown in Table 2.

[Equation 1]

Spread Ratio = {(H2-H1) x (A2-T2)} / {D x (A1-T1)}

(In Equation 1, H1 and H2 are the average values (unit mm) of the heights measured from the ground to the four vertices after unrolling the roll shape and leaving the first or second standing, respectively, and A1 and A2 are 4 of the film When the vertices are a1, a2, b1, b2, the average value of the hypothetical shortest distance between a1 and a2 and the hypothetical shortest distance between b1 and b2 measured after unrolling the roll shape and leaving the first or second standing, respectively (unit mm), T1 and T2 are the first or second standing time (unit min), respectively, and D is the thickness of the film (unit: um).

Here, the first leaving time was 1 minute and the second leaving time was 30 minutes, and H1 and H2, A1 and A2 were measured in the following manner.

That is, a polyimide-based film having a size of 100 mm x 100 mm is rolled so that the inner diameter from the center to the end becomes 6 mm and stored in the form of a polyimide-based film roll for 3 days, then unrolled and positioned as shown in FIG. The first standing time was left for 1 minute, and the average value (unit mm) of the height measured from the ground to the four vertices was recorded as H1 in Table 2 below.

The same method was repeated, but the average value of the height measured from the ground to the four vertices after leaving it for 30 minutes as the second leaving time was recorded as H2 in Table 2 below.

In addition, when four vertices of a polyimide-based film having a size of 100 mm x 100 mm are referred to as a1, a2, b1, b2, after unrolling the roll shape, it is allowed to stand for 1 minute as the first standing time, and between a1 and a2 among the vertices The average value (unit mm) of the hypothetical shortest distance and the hypothetical shortest distance between b1 and b2 was recorded as A1 in Table 2 below.

The same method was repeated, but after leaving for 30 minutes as the second leaving time, the average value of the imaginary shortest distance between a1 and a2 and the imaginary shortest distance between b1 and b2 among the vertices was recorded as A2 in Table 2 below.

H1(mm) A1 (mm) H2(mm) A2 (mm) Calculated value of Equation 1 Example 1 32 55 28 71 3.098 Example 2 35 18 34 33 0.6875 Example 3 34 20 33 35 0.6562 Comparative Example 1 32 51 64 29 incalculable Comparative Example 2 35 16 34 29 4.0781

Referring to Table 2, in the polyimide-based films or film bodies of Examples 1 to 3 according to the present invention, the transmittance, haze, and yellowness measured in the film according to the curing conditions used to prepare the film were specific. Even within the range, it can be seen that the film deformation is suppressed only when the spread ratio calculated by Equation 1 is 0.1 to 4.0.

Therefore, it can be seen that the spread rate of the polyimide-based film is significantly affected by curing conditions, specifically, curing temperature, during the manufacturing process of the polyimide-based film.

As a result, the polyimide-based film according to the embodiment of the present invention can provide a polyimide-based film that satisfies the spreadability value specified in the present invention and significantly suppresses deformation, and at the same time has high optical properties, It is suitably used as a base film used for manufacture of flexible display apparatuses, etc. which require strict dimensional precision.

Features, structures, effects, etc. illustrated in each of the above-described embodiments may be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

a1, a2, b1, b2: the four vertices of the polyimide-based film
h1, h2, h3, h4: height measured from the ground to the 4 vertices of the film after unrolling
a: the shortest distance virtually connecting the vertices a1 and a2
b: the shortest distance virtually connecting the vertices b1 and b2

Claims (16)

A polyimide-based film containing a copolymer of a diamine compound, a dianhydride compound, and a dicarbonyl compound, and having a size of 100 mm x 100 mm, is rolled so that the inner diameter from the center to the end is 6 mm in the form of a polyimide-based film roll 3 After storage for one day, the roll shape is unwrapped and then placed as shown in FIG. 1, and the polyimide-based film having an expandability value of 0.1 to 4.0 according to Equation 1 below.
[Equation 1]
Spread Ratio = {(H2-H1) x (A2-T2)} / {D x (A1-T1)}
(In Equation 1, H1 and H2 are the average values (unit mm) of the heights measured from the ground to the four vertices after unrolling the roll shape and leaving the first or second standing, respectively, and A1 and A2 are 4 of the film When the vertices are a1, a2, b1, b2, the average value of the imaginary shortest distance between a1 and a2 and the imaginary shortest distance between b1 and b2 measured after unrolling the roll shape and leaving the first or second standing, respectively (unit mm), T1 and T2 are the primary or secondary exposure time (unit min), respectively, and D is the film thickness (unit: um). According to claim 1,
The polyimide-based film is a polyimide-based film having a value of the spread ratio according to Equation 1 in the range of 0.5 to 4.0. According to claim 1,
The polyimide-based film is a polyimide-based film having an expandability value in the range of 0.6 to 3.5 according to Equation 1. According to claim 1,
When the thickness of the polyimide-based film is 10 to 150 μm, the polyimide having the average value of the height measured from the ground to the four vertices of 35 or less after unrolling the roll shape, placing it as shown in FIG. 1 and leaving it for 1 minute based film. According to claim 1,
When the thickness of the polyimide-based film is 10 to 150 μm, when the four vertices of the film are a1, a2, b1, b2, the virtual between a1 and a2 measured after unrolling the roll shape and leaving it for 1 minute The average value of the shortest distance between b1 and b2 and the average value of the shortest distance between b1 and b2 satisfies 18 or more. According to claim 1,
When the thickness of the polyimide-based film is 10 to 150 μm, the polyimide having the average value of the height measured from the ground to the four vertices of 34 or less after unrolling the roll shape, placing it as shown in FIG. 1 and leaving it for 30 minutes based film. According to claim 1,
When the thickness of the polyimide-based film is 10 to 150 μm, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 30 minutes, and the imaginary shortest distance between a1 and a2 A polyimide-based film in which the average value of the distance and the virtual shortest distance between b1 and b2 satisfies 33 or more. According to claim 1,
When the thickness of the polyimide-based film is 20 to 55 μm, the polyimide having the average height measured from the ground to the four vertices of 32 or less after unrolling the roll shape, positioning it as shown in FIG. 1 and leaving it for 1 minute based film. According to claim 1,
When the thickness of the polyimide-based film is 20 to 55 μm, after unrolling the roll shape, it is placed as shown in FIG. 1, left for 30 minutes, and the average value of the height measured from the ground to the four vertices is 28 or less. based film. According to claim 1,
When the thickness of the polyimide-based film is 20 to 55 μm, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 1 minute, and virtual between a1 and a2 among the vertices The average value of the shortest distance between b1 and b2 and the average value of the shortest distance between b1 and b2 satisfies 55 or more. According to claim 1,
When the thickness of the polyimide-based film is 20 to 55 μm, when the four vertices of the film are a1, a2, b1, b2, the roll shape is unwrapped and left for 30 minutes, and the imaginary shortest distance between a1 and a2 A polyimide-based film in which the average value of the distance and the shortest virtual distance between b1 and b2 satisfies 71 or more. preparing a liquid resin composition using a diamine compound, a dianhydride compound, and a dicarbonyl compound;
using the liquid resin composition to prepare a film in a gel state;
drying the film in the gel state at 50 to 150° C. for 2 to 30 minutes; And After the drying step, stretching the film in the gel state and curing the film at 120 to 320 ℃ at a wind speed of 1.0 to 3.0 m / s for 1 minute to 2 hours; Method of producing a polyimide-based film comprising a. 13. The method of claim 12,
The step of preparing the liquid resin composition,
reacting the monomer components in the presence of a first solvent to prepare a polymer solution;
preparing a polymer solid by adding a second solvent to the polymer solution, filtration and drying; and
A method for producing a polyimide-based film comprising the step of dissolving the polymer solid in a third solvent. 13. The method of claim 12,
The stretching is performed by reflecting the shrinkage value according to Equation 2 below,
The shrinkage rate is within the range of 2% or less when TMA measurement is carried out in a nitrogen atmosphere while the temperature is raised from room temperature to 350°C by 10°C/min using TA Instrument's TMAQ400 from room temperature to 280°C. Method of producing a polyimide-based film.
[Equation 2]
Shrinkage: {(length before measurement - length after measurement)/length before measurement} x 100 A polyimide-based film body comprising the polyimide-based film of claim 1,
On one side or both sides of the polyimide-based film, a primer film, a hardness-reinforced film, a flexible film, a folding film, a flexural strength reinforcement film, a visibility improvement film, a barrier film, an antibacterial film, a water-repellent film, an anti-fingerprint film, a reflection A polyimide-based film body comprising at least one selected from an anti-aging film and a film providing a smooth touch. glass cover; and
A window member comprising a polyimide-based film provided on at least one surface of the glass cover,
The polyimide-based film is a window member that is the polyimide-based film according to any one of claims 1 to 14.

Images