WO2020054912A1

WO2020054912A1 - Polyimide film having improved surface quality and method for manufacturing same

Info

Publication number: WO2020054912A1
Application number: PCT/KR2018/014615
Authority: WO
Inventors: 김동영; 원동영; 최정열
Original assignee: 에스케이씨코오롱피아이 주식회사
Priority date: 2018-09-12
Filing date: 2018-11-26
Publication date: 2020-03-19
Also published as: CN111295411A; CN111295411B; KR20200030268A; KR102171061B1

Abstract

The present invention provides a polyimide film manufactured by imidization of a polyamic acid in which a first dianhydride, a second dianhydride, a first diamine, and a second diamine are polymerized.

Description

Polyimide film with improved surface quality and method for manufacturing the same

The present invention relates to a polyimide film having improved surface quality and a method for manufacturing the same.

Polyimide (PI) is a polymer having the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials, based on an imide ring with excellent chemical stability along with a rigid aromatic backbone It is material. Accordingly, polyimide has been spotlighted as an insulating material for microelectronic components in which the aforementioned properties are strongly required.

Examples of the microelectronic component include a thin circuit board having high circuit density and being flexible so that it can cope with the reduction in weight and size of electronic products, and the polyimide is widely used as an insulating film for thin circuit boards.

The thin circuit board has a structure in which a circuit including a metal foil is formed on an insulating film, and the thin circuit board is referred to as a flexible metal foil clad laminate in a broad sense and refers to a thin copper plate with a metal foil. When used, it is also referred to as a flexible copper clad laminate (FCCL) in a narrower sense.

As a method of manufacturing a flexible metal foil-clad laminate, for example, (i) casting or imposing a polyamic acid, a precursor of polyimide, on a metal foil, followed by imidization, and (ii) sputtering. Thereby, a metallization method in which a metal layer is directly provided on a polyimide film, and (iii) a lamination method in which a polyimide film and a metal foil are bonded by heat and pressure through a thermoplastic polyimide. For reference, the double metallization method, for example, by sputtering a metal such as copper on a polyimide film having a thickness of 20 to 38 μm, sequentially depositing a tie layer and a seed layer to form a flexible metal thin-layer laminate. It is a method of producing, and has an advantage in forming an ultra-fine circuit having a pitch of a circuit pattern of 35 µm or less, and is widely used to manufacture a flexible metal foil laminate for COF (chip on film).

In recent years, the pitch between the microcircuits and the line width of each of them has been further downward, and as a result, the total area of the metal plate is decreasing, and an increase in adhesion and adhesion between the polyimide film and the metal plate is strongly required.

The adhesion and adhesion with the metal plate can be greatly improved depending on the surface condition of the polyimide film.

For example, surface defects such as nubs, wrinkles, and protrusions formed on the surface of the polyimide film may act as factors that reduce adhesion and adhesion to the metal deposited by sputtering, and conversely, when the surface of the polyimide film is smooth, The degree of adhesion and adhesion with the metal may be excellent at a desired level.

The surface defect is a major reason that gels or bubbles formed in the process of converting polyamic acid, a precursor of polyimide, into polyimide remain in the polyimide film after conversion is completed. You can.

In addition to the causes of surface defects in the film, these gels and bubbles may also act as one factor causing cracks in the polyimide film.

Accordingly, there is a high need for a polyimide film having a smooth surface without surface defects caused by gels or bubbles.

The main object of the present invention is to provide a polyimide film having a smooth surface and suitable for manufacturing a flexible metal foil laminate.

The present invention uses a specific monomer for the implementation of the polyimide film and implements its content range according to a specific embodiment of the present invention, so that there is substantially no generation of gels and bubbles, and no surface defects derived therefrom. It is possible to implement a polyimide film having surface properties.

In addition, the polyimide film may have an appropriate level of glass transition temperature and coefficient of thermal expansion that can be used as an insulating film for a flexible metal foil-clad laminate.

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

In one embodiment, the present invention is prepared by imidizing a polyamic acid prepared by polymerization of a first dianhydride, a second dianhydride, a first diamine and a second diamine, and for the first dianhydride It provides a polyimide film, wherein the molar ratio of the first diamine (= first diamine / first dianhydride) is greater than 1 to less than 2.

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

In one embodiment, the present invention provides a flexible metal foil laminate comprising the polyimide film and an electronic device including the same.

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

Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor appropriately explains the concept of terms in order to explain his or her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

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

In the present specification, a singular expression includes a plural expression unless the context clearly indicates otherwise. In this specification, the terms "include", "have" or "have" are intended to indicate the presence of implemented features, numbers, steps, elements or combinations thereof, one or more other features or It should be understood that the existence or addition possibilities of numbers, steps, elements, or combinations thereof are not excluded in advance.

As used herein, "dianhydride (dianhydride)" is intended to include its precursors or derivatives, which may not technically be dianhydrides, but will nevertheless react with diamines to form polyamic acids. And this polyamic acid can be converted back to polyimide.

“Diamine” as used herein is intended to include precursors or derivatives thereof, which may not technically be diamines, but will nevertheless react with dianhydrides to form polyamic acids, which are polyamic The acid can be converted back to polyimide.

When an amount, concentration, or other value or parameter herein is given as an enumeration of a range, a preferred range, or a preferred upper and lower limits, any upper limit of any pair of any pair, regardless of whether the ranges are disclosed separately or It should be understood that the specific values and any lower range limits or all ranges that can be formed with the desired values are specifically disclosed. When a range of numerical values is referred to herein, unless stated otherwise, eg, unless there is a limiting term such as greater than, less than, the range is intended to include the endpoint and all integers and fractions within the range. It is intended that the scope of the invention not be limited to the specific values recited when defining a range.

폴리이미드 필름Polyimide film

The polyimide film according to the present invention,

A polyimide film produced by imidizing a polyamic acid produced by polymerization of a first dianhydride, a second dianhydride, a first diamine, and a second diamine,

The first dianhydride is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3', 4'-biphenyltetracarboxylic dianhydride Ride (a-BPDA) is at least one member selected from the group consisting of,

The first diamine is at least one member selected from the group consisting of paraphenylenediamine (PPD) and metaphenylenediamine (MPD),

The second dianhydride includes at least one dianhydride different from the first dianhydride,

The second diamine includes at least one diamine different from the first diamine,

The molar ratio of the first diamine to the first dianhydride (= first diamine / first dianhydride) may be greater than or less than 1.

In the conversion from polyamic acid to polyimide film, there are complex reasons for the creation of gels and bubbles, but one of them may be related to 'imidation'. Here, imidization refers to a phenomenon, process, or method in which the amic acid group is converted to an imide group by inducing a ring-closure and dehydration reaction of an amic acid group forming a polyamic acid through heat and / or a catalyst.

Generally, if the imidization proceeds excessively quickly, some of the bulk of the polyamic acid solution (or gel film) may show a deviation from the level of the imidization progress of the other.

For example, when a polyamic acid solution is applied on a support, imidization proceeds relatively slowly at a core (center) portion of the polyamic acid solution (or gel film) in the applied state and a portion adjacent thereto, and vice versa. The imidization may proceed relatively quickly in a region in contact with or exposed to the outside.

At this time, in the portion where the imidization is progressing slowly, only a part of the amic acid group may form a gel with the polymer chain converted to the imide group remaining moisture or a solvent, and the gel formed as such is normally formed by imidization. It can be isolated by a portion of the polyimide and present inside the polyimide film.

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

In addition, during the imidization process, gas is generated inside the polyamic acid solution (or gel film) due to evaporation of moisture and solvent, and the gas may generate bubbles in the polyamic acid solution (or gel film).

However, the polyamic acid solution gradually solidifies in the form of a polyimide film through a gel film. When the imidization process is performed too slowly, gas is slowly generated and the exhaust rate of the gas is delayed. In this case, it is easy to trap the gas inside the solution and the film gradually solidifying, and the resulting bubbles may not be easily extinguished and may be isolated at the location. As a result, the finally obtained polyimide film may include empty spaces due to the bubbles.

Therefore, it is possible that the imidization process is performed at an appropriate level to suppress the formation of gels and bubbles.

Controlling the progress of imidization may include, but is not limited to, a number of factors, such as the temperature, time, catalyst added to the imidization, its content and type, etc., and may be determined by such attachment means. The present invention has been found that the type, content and ratio of diamine and dianhydride constituting polyamic acid and further polyimide may also affect at least part of the progress of imidation.

Specifically, PPD and / or MPD, which are the first diamines, may have a property of inducing that the dehydration reaction of the ring by imidization proceeds relatively rapidly, despite the secondary means.

On the other hand, the BPDA-based material, which is the first dianhydride, may have a property that induces the ring-closed dehydration reaction by imidation to proceed relatively slowly. Therefore, when the first diamine and the first dianhydride are combined in a predetermined ratio, imidization may proceed to an appropriate level.

In one specific example of this, the molar ratio of the first diamine to the first dianhydride (= first diamine / first dianhydride) is greater than 1 to less than 2, specifically 1.6 to 1.9, more detailed It may be 1.7 to 1.8, in particular 1.72.

The appropriate level may be, for example, a level in which gels and bubbles are less produced without controlling the secondary means. The level of low generation of gels and / or bubbles can be quantified, for example, by the number of surface defects per area of 10 cm * 10 cm of the polyimide film, and the polyimide film according to the present invention has an area of 10 cm * 10 cm The number of sugar surface defects is 1 or less, specifically 0, and has very smooth surface properties.

However, although the molar ratio is satisfied, when the first dianhydride has an excessively small number of moles based on the total number of moles of the polyamic acid, chemical resistance of the polyimide film may be lowered. Conversely, when the number of moles of the first dianhydride is large, it may cause a decrease in the glass transition temperature of the polyimide film and an excessive increase in the coefficient of thermal expansion.

In addition, when the molar ratio is satisfied, but the first diamine has an excessively large number of moles based on the total number of moles of the polyamic acid, the thermal expansion coefficient of the polyimide film may be significantly lowered. Conversely, when the number of moles of the first diamine is small, the glass transition temperature can be lowered.

Therefore, while satisfying the molar ratio, it may be preferable that the first diamine and the first dianhydride are included in a predetermined content.

In one specific example, the content of the first dianhydride may be 40 to 50 mol% based on the total number of moles of the first dianhydride and the second dianhydride, and the second dianhydride The content of may be 50 to 60 mol%.

In addition, the first diamine may be 80 to 92 mol% based on the total number of moles of the first diamine and the second diamine, and the second diamine may be 8 to 20 mol%.

Meanwhile, the second diamine may include one or more selected from the group consisting of 4,4'-diaminodiphenyl ether (oxydianiline, ODA) and 3,4'-diaminodiphenyl ether.

Such a second diamine can preferably act to improve the transparency of the polyimide film. In addition, since the second diamine has a relatively flexible structure by containing two benzene rings in a molecular structure, it may also be preferable in that it can impart an appropriate linear expansion coefficient to the polyimide film.

The second dianhydride is pyromellitic dianhydride (PMDA), oxydiphthalic dianhydride (ODPA), diphenylsulfone-3,4,3 ', 4'-tetracarboxylic dianhydride ( DSDA), 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride (or BTDA) and 2,2-bis [(3,4-dicarboxy phenoxy) phenyl] propane dianhydride (BPADA) may be one or more selected from the group consisting of, in detail, may be pyromellitic dianhydride (PMDA).

In one specific example, the first dianhydride, the second dianhydride, the first diamine, and the second diamine are 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, and fatigue, respectively. It may be melic dianhydride, paraphenylenediamine and 4,4'-diaminodiphenyl ether.

The polyimide film derived from the combination of the diamine and the dianhydride may have a desirable level of thermal expansion coefficient and glass transition temperature applicable to a flexible metal foil laminate while having smooth surface characteristics as described above.

In one specific example, the polyimide film has a coefficient of thermal expansion of 2 to 7 μm / m * ° C, specifically 2 to 5 μm / m * ° C, and a glass transition temperature of 370 ° C or higher, and specifically 380 ° C or higher. You can.

For example, the flexible metal foil-clad plate has a metal foil thereof, typically having a thermal expansion coefficient of 16 μm / m * ° C to 17 μm / m * ° C, and when forming a metal foil by sputtering on a polyimide film, the polyimide film It may be desirable to have a lower coefficient of thermal expansion than the metal foil, specifically, it is preferable that the polyimide film has a coefficient of thermal expansion of 2 to 7 µm / m * ° C, and more specifically 2 to 5 µm / m * ° C. You can. Therefore, since the polyimide film according to the present invention may have a coefficient of thermal expansion within the above-described preferred range, there is an advantage in implementing a flexible metal foil-clad laminate.

When the glass transition temperature is lower than the above temperature, it is not preferable from the viewpoint of heat resistance. However, it is also undesirable that the glass transition temperature is too high.

Specifically, if the polyimide film has an excessively high glass transition temperature, an extremely low thermal expansion coefficient of less than 0.1 μm / m * ° C may be exhibited, or a negative thermal expansion coefficient may be expressed. In this case, when implementing the flexible metal foil-clad laminate, the thermal expansion coefficient between the polyimide film and the metal foil is considerably different, which may lead to a decrease in adhesion between the two and defects such as cracks.

Accordingly, the polyimide film may be more advantageous for the production of a flexible metal foil laminate when the glass transition temperature is 370 ° C to 400 ° C, and specifically 380 ° C to 400 ° C.

폴리이미드 필름의 제조방법Manufacturing method of polyimide film

Method for producing a polyimide film according to the present invention,

(a) polymerizing the polyamic acid; And

(b) imidizing the polyamic acid to obtain a polyimide film.

Step (a) is,

(a-1) mixing and polymerizing the first dianhydride and the first diamine; And

(a-2) The second dianhydride and the second diamine are additionally added, or the first diamine, the second dianhydride and the second diamine are additionally added, from step (a-1). It may include the step of extending the end of at least a portion of the prepared polymer.

After the step (a-2), (a-3) the total number of moles of the first dianhydride and the second dianhydride and the total number of moles of the first diamine and the second diamine are substantially equimolar, in detail The second dianhydride may be further added to polymerize to a molar ratio of 0.997 to 0.999, and more specifically 0.998.

In the step (a-1) and / or the step (a-2), an organic solvent may be mixed with dianhydride and diamine.

The organic solvent is not particularly limited as long as it is a solvent in which polyamic acid can be dissolved, but as an example, the organic solvent may be an aprotic polar solvent.

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

In some cases, the solubility of the polyamic acid may be controlled by using auxiliary solvents such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, and water. In one example, the organic solvent that can be particularly preferably used in the production of the polyamic acid of the present invention may be amide solvents N, N'-dimethylformamide and N, N'-dimethylacetamide.

The polyamic acid prepared as described above may have a weight average molecular weight of 150,000 g / mole or more to 1,000,000 g / mole or less, specifically 260,000 g / mole or more to 700,000 g / mole or less, and more specifically 280,000 g / mole It may be greater than or equal to 500,000 g / mole or less.

Polyamic acid having such a weight average molecular weight may be preferable for the production of a polyimide film having better heat resistance and mechanical properties.

In general, the weight average molecular weight of the polyamic acid may be proportional to the viscosity of the precursor composition containing the polyamic acid and the organic solvent, and the viscosity may be adjusted to control the weight average molecular weight of the polyamic acid to the above range.

This is because the viscosity of the precursor composition is proportional to the content of the polyamic acid solid content, specifically, the total amount of the dianhydride monomer and the diamine monomer used in the polymerization reaction. However, the weight average molecular weight does not represent a linear proportional relationship of one dimension to the viscosity, but is proportional to the form of a logarithmic function.

That is, while increasing the viscosity in order to obtain a higher weight average molecular weight polyamic acid, while the range in which the weight average molecular weight can be increased is limited, if the viscosity is too high, the precursor composition through a die in the film forming process of the polyimide film When discharging, it may cause a processability problem due to an increase in pressure inside the die.

Accordingly, the precursor composition of the present invention may include 15% to 20% by weight of a polyamic acid solid content and 80% to 85% by weight of an organic solvent, and in this case, a viscosity of 90,000 cP or more to 300,000 cP or less, in detail It may be 100,000 cP or more to 250,000 cP. Within this viscosity range, the weight average molecular weight of the polyamic acid may fall within the above range, and the precursor composition may not cause problems in the film forming process described above.

Meanwhile, a filler may be added during the production of the polyamic acid for the purpose of improving various properties of the film such as sliding property, thermal conductivity, conductivity, corona resistance, and loop hardness of the polyimide film. The filler to be added is not particularly limited, and preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

The average particle diameter of the filler is not particularly limited, and can be determined according to the characteristics of the polyimide film to be modified and the type of filler to be added. In one example, the average particle diameter of the filler may be 0.05 μm to 100 μm, specifically 0.1 μm to 75 μm, more preferably 0.1 μm to 50 μm, and particularly specifically 0.1 μm to 25 μm.

If the average particle diameter is less than this range, the modification effect is unlikely to appear, and if it exceeds this range, the filler may significantly impair the surface properties of the polyimide film or cause mechanical properties of the film to deteriorate.

Moreover, the addition amount of the filler is not particularly limited, and can be determined by the characteristics of the polyimide film to be modified, the particle size of the filler, and the like.

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

If the amount of the filler added is less than this range, the modification effect by the filler is unlikely to appear, and if it exceeds this range, the mechanical properties of the polyimide film may be greatly deteriorated. The method for adding the filler is not particularly limited, and any known method can be used.

Meanwhile, the step (b),

(b-1) preparing a film-forming composition by mixing the polyamic acid, a dehydrating agent, and an imidizing agent;

(b-2) preparing a gel film by first heat-treating the film-forming composition at 50 to 150 ° C; And

(b-3) a second heat treatment of the gel film at 200 to 600 ° C,

The dehydrating agent is added with respect to 1 mole of the amic acid group in the polyamic acid, from 3.5 mole to 6.0 mole, specifically from 4.0 mole to 5.5 mole, and the imidizing agent is added from 0.7 mole to 1.2 mole, specifically 0.8 mole to 1.0 mole Can be.

Here, the term “dehydrating agent” refers to a substance that promotes a cyclization reaction through dehydration of a polyamic acid, and includes, without limitation, aliphatic acid anhydrides, aromatic acid anhydrides, N, N'- Dialkyl carbodiimide, halogenated lower aliphatic, halogenated lower patty acid anhydride, aryl phosphonic dihalide, thionyl halide, and the like. Of these, aliphatic acid anhydrides may be preferred from the viewpoint of ease of availability and cost, and non-limiting examples thereof include acetic anhydride (AA), propion acid anhydride, and lactic acid anhydride. Etc. are mentioned, These can be used individually or in mixture of 2 or more types.

In addition, "imide agent" means a substance having an effect of promoting a ring-closure reaction to a polyamic acid, for example, an imine-based component such as an aliphatic tertiary amine, an aromatic tertiary amine, and a heterocyclic tertiary amine. You can. Of these, heterocyclic tertiary amines may be preferable from the viewpoint of reactivity as a catalyst. Non-limiting examples of heterocyclic tertiary amines include quinoline, isoquinoline, β-picoline (BP), pyridine and the like, and these can be used alone or in combination of two or more.

When the dehydrating agent and the imidizing agent fall below the above range, chemical imidization is insufficient, cracks may be formed in the polyimide film to be produced, and mechanical strength of the film may also be lowered. In addition, if these addition amounts exceed the above range, imidization may proceed excessively rapidly, and in this case, it may be difficult to cast in the form of a film or the produced polyimide film may exhibit brittle characteristics, which is not preferable. not.

In the step of preparing the gel film, a film-forming composition containing a dehydrating agent and / or an imidizing agent is cast in a film form on a support such as a glass plate, aluminum foil, endless stainless belt, or stainless drum, and then on the support. The film-forming composition is first heat-treated at a variable temperature in the range of 50 ° C to 200 ° C, specifically 50 ° C to 150 ° C. In this process, a dehydrating agent and / or an imidizing agent acts as a catalyst so that the amic acid group can be quickly converted to an imide group.

In some cases, in order to control the thickness and size of the polyimide film obtained in the second heat treatment process and improve the orientation, between the steps (b-2) and (b-3), the gel film is stretched. The process may be performed, and stretching may be performed in at least one of a machine transport direction (MD) and a transverse direction (TD) with respect to the machine transport direction.

The gel film thus obtained is fixed to a tenter and then subjected to a second heat treatment at a variable temperature in the range of 50 ° C to 650 ° C, specifically 200 ° C to 600 ° C to remove water, catalyst, residual solvent, and the like remaining in the gel film. Then, almost all the remaining amic acid groups are imidized to obtain the polyimide film of the present invention. In such a heat treatment process, a dehydrating agent and / or an imidizing agent acts as a catalyst, so that the amic acid group can be rapidly converted to an imide group, thereby realizing a high imidization rate.

In some cases, the polyimide film obtained as described above may be heated to a temperature of 400 ° C. to 650 ° C. for 5 seconds to 400 seconds to further harden the polyimide film, and may remain inside the obtained polyimide film. It can also be done under a given tension to relieve stress.

1 is a photograph of the surface of the polyimide film according to Example 1.

2 is a photograph of the surface of the polyimide film according to Comparative Example 1.

3 is a photograph of the surface of the polyimide film according to Comparative Example 2.

4 is a photograph of the surface of the polyimide film according to Comparative Example 3.

5 is a photograph of the surface of the polyimide film according to Comparative Example 4.

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

While maintaining the inside of the reaction system at 10 ° C, s-BPDA as the first dianhydride and PPD as the first diamine were added to the DMF in the molar ratio shown in Table 1 below, and polymerization was performed while stirring for 1 hour.

Thereafter, first PMDA as the second dianhydride and ODA as the second diamine were added at a molar ratio shown in Table 1 and stirred for 1 hour to perform polymerization.

Subsequently, as the second dianhydride, the second PMDA was added in the molar ratio shown in Table 1, so that the total number of moles of the first dianhydride, the second dianhydride, and the first diamine and the second diamine was substantially equimolar. And stirred for 1 hour, the polymerization was terminated when the viscosity reached 1100 to 1300 poise (poise) to prepare a final polyamic acid.

To the final polyamic acid thus obtained, 5.5 mole ratio of acetic anhydride and 1.1 mole ratio of isoquinoline with respect to 1 mole of amic acid group were added together with DMF, and the obtained mixture was applied to a stainless steel plate and cast using a doctor blade using a 400 μm gap. Then, the first heat treatment was performed at 50 to 150 ° C for 4 minutes to prepare a gel film.

The gel film thus prepared was removed from the stainless steel plate, fixed with a frame pin, and then heat-treated at 400 ° C. for 7 minutes for a frame on which the gel film was fixed to remove the film to obtain a polyimide film having an average thickness of 15 μm.

A polyimide film having a thickness of 15 μm was obtained in the same manner as in Example 1, except that the molar ratios of the first diamine and the second diamine were changed as shown in Table 1.

A polyimide film having a thickness of 15 μm was obtained in the same manner as in Example 1, except that the molar ratios of the first dianhydride, the second dianhydride, the first diamine, and the second diamine were changed as shown in Table 1.

	디안하이드라이드 (몰%)Diane hydride (mol%)			디아민 단량체 (몰%)Diamine monomer (mol%)		제1 디아민/제1 디안하이드라이드의 몰비Molar ratio of first diamine / first dianhydride
	제1 디안하이드라이드(s-BPDA)First dianhydride (s-BPDA)	제2 디안하이드라이드The second dianhydride		제1 디아민(PPD)First diamine (PPD)	제2 디아민(ODA)Second Diamine (ODA)
	제1 디안하이드라이드(s-BPDA)First dianhydride (s-BPDA)	제1 PMDA1st PMDA	제2 PMDA2nd PMDA	제1 디아민(PPD)First diamine (PPD)	제2 디아민(ODA)Second Diamine (ODA)
실시예 1Example 1	5050	4949	1One	8787	1313	1.741.74
실시예 2Example 2	5050	4949	1One	9292	88	1.841.84
실시예 3Example 3	5050	4949	1One	8080	2020	1.61.6
비교예 1Comparative Example 1	7070	2929	1One	6060	4040	0.850.85
비교예 2Comparative Example 2	3030	6969	1One	6060	4040	22
비교예 3Comparative Example 3	3030	6969	1One	9090	1010	33
비교예 4Comparative Example 4	5050	4949	1One	5050	5050	1One
비교예 5Comparative Example 5	5050	4949	1One	7575	2525	1.41.4
비교예 6Comparative Example 6	5050	4949	1One	96.296.2	3.83.8	1.91.9

The surfaces of the polyimide films obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were visually observed to confirm the number of surface defects per area of 10 * 10 cm, and classified according to grades, and the results are shown in Table 2 below. .

	표면 결함 등급Surface defect class
실시예 1Example 1	SS
실시예 2Example 2	SS
실시예 3Example 3	SS
비교예 1Comparative Example 1	CC
비교예 2Comparative Example 2	CC
비교예 3Comparative Example 3	BB
비교예 4Comparative Example 4	BB

** Grade S: 0 surface defects; Grade A: surface defects: 5 or less; No more than 10 grade B surface defects; > 10 grade C surface defects

Referring to Table 2, the molar ratio of the first dianhydride and the first diamine and the number of moles of the first and second dianhydride and the mole number of the first and second diamine are examples in which the surface defects are within the scope of the present invention. No, it can be seen that it has a smooth surface property.

In this regard, FIG. 1 shows a photograph of the surface of the polyimide film prepared in Example 1, and referring to this, it can be seen that the polyimide film has no protrusions on the surface and the surface is smooth.

In contrast, in Comparative Examples 1 to 4, wherein the molar ratio and the number of moles were outside the scope of the present invention, a number of surface defects were formed on the surface of the polyimide film.

Thus, FIG. 2 shows a photograph of the surface of the polyimide film prepared in Comparative Example 1 and FIG. 3 shows a photograph of the surface of the polyimide film prepared in Comparative Example 2.

These comparative examples are examples in which the molar ratio of the first dianhydride and the first diamine is outside the scope of the present invention, and the first dianhydride is included in a relatively excessive or small amount to produce a polyimide film. Bubbles were formed, and as a result, as can be seen in FIGS. 2 and 3, a number of protrusions derived from bubbles were induced on the polyimide surface on which production was completed.

Meanwhile, FIGS. 4 and 5 show photographs of the surfaces of the polyimide films prepared in Comparative Examples 3 and 4, respectively.

Comparative Examples 3 and 4 are examples in which the polyimide film was prepared using a relatively large or small amount of the first diamine because the molar ratio of the first dianhydride and the first diamine is outside the scope of the present invention. The gel was formed, and as a result, a number of protrusions derived from the gel were induced on the surface of the polyimide, which was completed as shown in FIGS. 4 and 5.

For each of the polyimide films prepared in Examples 1 to 3 and Comparative Examples 1 to 6, the glass transition temperature (T _g ) was measured using DMA, and the thermal expansion coefficient of each polyimide film was measured using TMA. Measurement was made, and the results are shown in Table 3.

	유리전이온도 (℃)Glass transition temperature (℃)	열팽창계수(㎛/m℃)Coefficient of thermal expansion (㎛ / m ℃)
실시예 1Example 1	385385	4.24.2
실시예 2Example 2	395395	2.22.2
실시예 3Example 3	370370	6.76.7
비교예 1Comparative Example 1	341341	12.312.3
비교예 2Comparative Example 2	410410	9.69.6
비교예 3Comparative Example 3	432432	1.11.1
비교예 4Comparative Example 4	355355	11.111.1
비교예 5Comparative Example 5	363363	7.97.9
비교예 6Comparative Example 6	422422	0.80.8

Referring to Table 3, comparative examples in which the molar ratio of the first dianhydride and the first diamine and the number of moles of the first and second dianhydride and the mole number of the first and second diamine are outside the scope of the present invention are glass transition temperatures. It can be seen that at least one of the and thermal expansion coefficient is excessive, from which it can be expected that it will be disadvantageous for the implementation of the flexible circuit board. On the contrary, it can be seen that the embodiment has an advantage in implementing a flexible circuit board, as it has an appropriate level of glass transition temperature and a desirable coefficient of thermal expansion.

Although described above with reference to the embodiments of the present invention, those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above.

As described above, the present invention provides a polyimide film having smooth surface properties, without defects due to gels and / or bubbles, due to the combination of specific dianhydride monomers and diamine monomers and their specific blending ratio. can do.

Claims

A polyimide film produced by imidizing a polyamic acid produced by polymerization of a first dianhydride, a second dianhydride, a first diamine, and a second diamine,

The first dianhydride is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3', 4'-biphenyltetracarboxylic dianhydride Ride (a-BPDA) is at least one member selected from the group consisting of,

The first diamine is at least one member selected from the group consisting of paraphenylenediamine (PPD) and metaphenylenediamine (MPD),

The second dianhydride includes at least one dianhydride different from the first dianhydride,

The second diamine includes at least one diamine different from the first diamine,

The polyimide film, wherein the molar ratio of the first diamine to the first dianhydride (= first diamine / first dianhydride) is more than 1 to less than 2.
According to claim 1,

The polyimide film is a polyimide film, the number of surface defects per area of 10 cm * 10 cm is 1 or less.
According to claim 1,

The polyimide film, wherein the molar ratio of the first diamine to the first dianhydride is 1.6 to 1.9.
According to claim 1,

The second dianhydride is pyromellitic dianhydride (PMDA), oxydiphthalic dianhydride (ODPA), diphenylsulfone-3,4,3 ', 4'-tetracarboxylic dianhydride (DSDA ), 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride (or BTDA) and 2,2-bis [(3,4-dicarboxy phenoxy) phenyl] propane dianhydride ( BPADA), polyimide film comprising at least one selected from the group consisting of.
According to claim 1,

The second diamine is a polyimide film comprising at least one member selected from the group consisting of 4,4'-diaminodiphenyl ether (oxydianiline, ODA) and 3,4'-diaminodiphenyl ether.
According to claim 1,

The first dianhydride, the second dianhydride, the first diamine and the second diamine are 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, respectively. A polyimide film, which is paraphenylenediamine and 4,4'-diaminodiphenyl ether.
According to claim 1,

Based on the total number of moles of the first dianhydride and the second dianhydride, the content of the first dianhydride is 40 to 50 mol%, and the content of the second dianhydride is 50 to 60 mol%, Polyimide film.
According to claim 1,

The polyimide film, wherein the content of the first diamine is 80 to 92 mol% and the content of the second diamine is 8 to 20 mol% based on the total number of moles of the first diamine and the second diamine.
According to claim 1,

The polyimide film has a thermal expansion coefficient of 2 to 7 μm / m * ° C, and a glass transition temperature of 370 ° C or higher.
A method for manufacturing the polyimide film according to claim 1,

(a) polymerizing the polyamic acid; And

(b) imidizing the polyamic acid to obtain a polyimide film.
The method of claim 10,

Step (a) is,

(a-1) mixing and polymerizing the first dianhydride and the first diamine; And

(a-2) The second dianhydride and the second diamine are additionally added, or the first diamine, the second dianhydride and the second diamine are additionally added, from step (a-1). The method comprising the step of extending the end of at least a portion of the prepared polymer.
The method of claim 11,

After step (a-2),

(a-3) Polymerization by additionally introducing a second dianhydride so that the total number of moles of the first dianhydride and the second dianhydride and the total number of moles of the first and second diamines are substantially equimolar Method comprising the step.
The method of claim 10,

Step (b) is,

(b-1) preparing a film-forming composition by mixing the polyamic acid, a dehydrating agent, and an imidizing agent;

(b-2) preparing a gel film by first heat-treating the film-forming composition at 50 to 150 ° C; And

(b-3) a second heat treatment of the gel film at 200 to 600 ° C,

The method for preparing the dehydrating agent is added in an amount of 3.5 mol to 6.0 mol, and the imidizing agent is added in an amount of 0.7 mol to 1.2 mol based on 1 mol of the amic acid group in the polyamic acid.
A flexible metal foil laminate comprising the polyimide film according to claim 1.
An electronic device comprising the flexible metal foil laminate according to claim 14.