WO2020230966A1 - Polyimide precursor composition, method for preparing same, and polyimide - Google Patents

Abstract

The present application relates to a polyimide precursor composition, a method for preparing same, and polyimide. With respect to a polyimide precursor which needs to be kept or stored for a predetermined time, the present application provides a polyimide precursor composition which can secure storage stability and dimensional stability after curing and a method for preparing same.

Description

Polyimide precursor composition, preparation method thereof, and polyimide

Mutual citation with related applications

This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0055103 filed May 10, 2019, and all contents disclosed in the documents of the Korean patent application are included as part of this specification.

Technical field

The present application relates to a polyimide precursor composition, a method for preparing the same, and a polyimide.

Polyimide (PI) is a polymer material with thermal stability based on a rigid aromatic backbone and has mechanical properties such as excellent strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of the imide ring.

In addition, polyimide is in the spotlight as a high-functional polymer material applicable to a wide range of industries such as electronics, communication, and optics due to its excellent electrical properties such as insulation and low dielectric constant.

Recently, as various electronic devices become thinner, lighter, and smaller, many studies are being conducted to use a thin polyimide film with excellent flexibility as a display substrate that can replace an insulating material for a circuit board or a glass substrate for a display. .

In general, a polyimide film is prepared by applying a polyamic acid prepared by polymerization reaction of dianhydride and diamine onto a support and imidizing it to form a film, and peeling it from the support.

At this time, the polyamic acid contains both an amine group and a carboxylic acid group, and in particular, the hydroxy group in the carboxylic acid group may be hydrolyzed as it reacts with an adjacent amine group, so that the storage stability and viscosity stability of the polyimide precursor composition including the same are poor. Is known. In addition, this phenomenon is known to be more pronounced at room temperature or higher than at low temperature.

When the storage stability and viscosity stability of the polyimide precursor composition are poor, the viscosity may change significantly during the process or during a long time thawing process, and thus, the application and imidization of the polyimide precursor composition may be unstable. In addition, when the viscosity of the polyamic acid changes, it may cause a decrease in mechanical and thermal properties of the polyimide film.

The present application provides a polyimide precursor composition capable of securing storage stability and dimensional stability after curing for a polyimide precursor composition requiring storage or storage for a certain period of time, and a method of manufacturing the same.

The present application relates to a polyimide precursor composition.

The polyimide precursor composition of the present application may include a diamine monomer and a dianhydride monomer as polymerized units, and may include a first bonding unit having a bond dissociation energy of 650 KJ/mol or less. The range of the bond dissociation energy is not particularly limited, but the upper limit may be 650 KJ/mol or less, 630 KJ/mol or less, or 620 KJ/mol or less, and the lower limit is 300 KJ/mol or more or 500 KJ/mol or more. I can. The present application includes the polymer having the above-described binding unit, thereby maintaining the viscosity characteristics of the low-viscosity polyimide precursor composition, so that the precursor composition can semi-permanently secure storage stability.

The polyimide precursor composition of the present application may be a composition having low viscosity characteristics. The polyimide precursor composition of the present application may have a viscosity of 10,000 cP or less and 9,000 cP or less as measured by a Brookfield viscometer on the RV-7 spindle at 23° C. and a rotation speed of 0.5 rpm. The lower limit is not particularly limited, but may be 500 cP or more or 1000 cP or more. The present application provides a precursor composition having excellent processability by adjusting the viscosity range, so that a film or substrate having desired physical properties can be formed when forming a film or substrate.

As such, the polyimide precursor composition has an important low viscosity property, but it is not easy to maintain it. Polyamic acid contains both an amine group and a carboxylic acid group, and in particular, the hydroxy group in the carboxylic acid group may be hydrolyzed as it reacts with an adjacent amine group, and it is known that the storage stability and viscosity stability of the polyimide precursor composition containing the same are poor. . Accordingly, when the polyimide precursor composition is stored or stored for a certain period of time, there is a problem that some side reactions occur. However, the polyimide precursor composition according to the present application may semi-permanently reverse reaction or dissociate some bonding units, and thus, a polyimide precursor composition in a desired state may be provided with respect to the precursor composition at any time.

In a specific example of the present application, at least one of the diamine monomer and the dianhydride monomer may include a monomer including two or more aromatic rings connected by the first bonding unit. In addition, in one example, the polyimide precursor composition may further include a diamine monomer from which the first bonding unit is dissociated or a dianhydride monomer from which the first bonding unit is dissociated.

In addition, in the specific example of the present application, in the polyimide precursor composition, a diamine monomer is polymerized at the terminal, or a dianhydride monomer from which the first binding unit is dissociated is bonded to the diamine monomer polymerized at the terminal, or at the terminal. The diamine monomer from which the first bonding unit is dissociated may be bonded. In the case where the diamine monomer is polymerized at the terminal as the first example, the amine group of the diamine monomer at the terminal may be dissociated from some bonding units before the amide bond is formed.

In one embodiment, when a diamine monomer is polymerized at the end of the polyimide precursor composition, the viscosity may increase as the remaining dianhydride proceeds with some side reactions with the diamine monomer at the end. In this case, as a means of returning the viscosity again, the present application may dissociate the first binding unit of the dianhydride subjected to a side reaction. Accordingly, a monomer from which the first binding unit of the dianhydride is dissociated may be present in the polymerization unit. Alternatively, the present application may dissociate the first binding unit of the diamine monomer at the terminal in which the side reaction has been performed. In another example, the present application may dissociate some bonding units during the process of forming an amide bond in the amine group of the diamine monomer polymerized at the terminal. In this case, the polyimide precursor composition may be present in a state in which some of the bonding units are dissociated, and the present application may maintain the viscosity again at a low viscosity through this. The method for dissociating the bonding unit is not particularly limited, and a known method can be used.

In one example, as described above, the polyimide precursor composition of the present application may include a monomer including two or more aromatic rings in which the diamine monomer is connected by a first bonding unit. Even when the diamine monomer includes the first bonding unit, as described above, the first bonding unit may be dissociated, and the amine group of the terminal diamine monomer may be dissociated from some bonding units prior to formation of the amide bond. . In this case, the diamine monomer polymerized at the terminal may be in a state in which the first bonding unit is dissociated. Alternatively, the present application may dissociate some bonding units during the process of forming an amide bond in the amine group of the diamine monomer polymerized at the terminal.

In the case of a polyimide precursor composition, a low molecular weight substance and an unreacted substance may occur due to some side reactions occurring at room temperature or high temperature.The polyimide precursor composition of the present application suppresses the above side reactions, so the distribution of molecular weight is narrow. I can. In one embodiment, after the polyimide precursor composition is cured, its polydispersity may be 2.2 or less, 2.0 or less, 1.9 or less, or 1.8 or less. The lower limit of the polydispersity is not particularly limited, and may be 1.2 or more, 1.3 or more, or 1.5 or more. The present application may improve the storage stability of the precursor composition at room temperature and high temperature by adjusting the polydispersity.

In one example, the polyimide precursor composition may have a thermal decomposition temperature of 560°C or higher, 562°C or higher, 570°C or higher, 573°C or higher, 576°C or higher, and 577°C or higher after curing. The upper limit value is not particularly limited, but may be 1000° C. or less, or 800° C. or less. The polyimide precursor composition of the present application can minimize unreacted monomers by controlling the thermal decomposition temperature, and thereby provide a polyimide having a desired physical property.

In one embodiment, the polyimide precursor composition of the present application may have a weight average molecular weight of 10,000 to 100,000, 15,000 to 80,000, 18,000 to 70,000, 20,000 to 60,000, 25,000 to 55,000, or 30,000 to 50,000 after curing. In the present application, the term weight average molecular weight means a value converted to standard polystyrene measured by GPC (Gel permeation Chromatograph). By controlling the polydispersity of the polyimide having the weight average molecular weight of the present application, it is possible to minimize the unreacted monomer.

In addition, in one example, the polyimide precursor composition of the present application may have an elongation of 15% or more, 20% or more, or 30% or more after curing. The upper limit value is not particularly limited, but may be 50% or less or 45% or less.

In one example, the polyimide precursor composition of the present application may include a polyamic acid solution in which a diamine monomer and a dianhydride monomer are polymerized. In the present specification, the polyimide precursor composition may have the same meaning as the polyamic acid solution.

The dianhydride monomer that can be used in the preparation of the polyamic acid solution may be an aromatic tetracarboxylic dianhydride, and the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride (or PMDA), 3,3 ',4,4'-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (or a-BPDA), oxydiphthalic Dianhydride (or ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (or DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2 ,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxyl Rick dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, p-phenylenebis (trimelitic monoester acid anhydride), p-biphenylenebis (trimelitic monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3- Bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy) ) Biphenyl dianhydride, 2,2-bis [(3,4-dicarboxyphenoxy)phenyl] propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1 ,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride, etc. are mentioned.

The dianhydride monomer may be used alone or in combination of two or more as necessary, but the present application considers the aforementioned bond dissociation energy, for example, pyromellitic dianhydride (PMDA), 3, 3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) or 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA). I can.

In addition, the diamine monomer that can be used for preparing the polyamic acid solution is an aromatic diamine, and is classified as follows and examples thereof are given.

1) 1,4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzo As a diamine having one benzene nucleus in structure, such as an acid acid (or DABA), a diamine having a relatively rigid structure;

2) Diaminodiphenyl ether, such as 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (Methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl )-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane , 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzanilide, 3,3' -Dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine), 2,2'-dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxy Benzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenylsulfide, 3,4' -Diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone , 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4' -Dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(3- Aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodi Diamines having two benzene nuclei in structure, such as phenyl sulfoxide and 4,4'-diaminodiphenyl sulfoxide;

3) 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-amino Phenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (or TPE-Q), 1,4-bis(4-aminophenoxy) Benzene (or TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-diamino-4-(4-phenyl)phenoxybenzophenone, 3 ,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide) Benzene, 1,4-bis(4-aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis( 4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4- Diamines having three benzene nuclei in structure, such as bis[2-(4-aminophenyl)isopropyl]benzene;

4) 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis [3-(3-aminophenoxy)phenyl] ether, bis [3-(4-aminophenoxy)phenyl] ether, bis [4- (3-aminophenoxy)phenyl] ether, bis (4- (4-aminophenoxy) phenyl) ether, bis (3- (3-aminophenoxy) phenyl) ketone, bis (3- (4-aminophenoxy) Si) phenyl] ketone, bis (4-(3-aminophenoxy) phenyl) ketone, bis (4- (4-amino phenoxy) phenyl) ketone, bis (3- (3-aminophenoxy) phenyl) sulfide , Bis [3-(4-aminophenoxy)phenyl] sulfide, bis [4-(3-aminophenoxy) phenyl] sulfide, bis [4-(4-aminophenoxy) phenyl] sulfide, bis [3- (3-aminophenoxy)phenyl] sulfone, bis (3-(4-aminophenoxy) phenyl) sulfone, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) Si) phenyl] sulfone, bis (3-(3-aminophenoxy) phenyl) methane, bis (3- (4-aminophenoxy) phenyl) methane, bis (4- (3-aminophenoxy) phenyl ] Methane, bis [4-(4-aminophenoxy) phenyl] methane, 2,2-bis [3-(3-aminophenoxy) phenyl] propane, 2,2-bis [3-(4 -Aminophenoxy)phenyl] propane, 2,2-bis (4- (3-aminophenoxy) phenyl) propane, 2,2-bis (4- (4-aminophenoxy) phenyl) propane ( BAPP), 2,2-bis [3-(3-aminophenoxy) phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3-(4- Aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3 ,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, etc. Diamine with four phase benzene nuclei.

The diamine monomer may be used alone or in combination of two or more, as needed, and the present application considers the aforementioned bond dissociation energy, for example, 1,4-diaminobenzene (PPD), 1,3 -Diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene or 4,4'-methylenediamine (MDA).

In the present application, the polyimide precursor composition may include an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent in which polyamic acid can be dissolved, but may be an aprotic polar solvent as an example.

The aprotic polar solvent is, for example, an amide solvent such as N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), p-chlorophenol, o-chlorophenol, etc. Phenolic solvents, N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL), and Diglyme, and these may be used alone or in combination of two or more.

According to the present application, the solubility of polyamic acid may be adjusted by using an auxiliary solvent such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, and water in some cases.

In one example, the organic solvent may be, for example, N-methyl-pyrrolidone (NMP).

On the other hand, the polyimide precursor composition of the present application may include a filler for the purpose of improving various properties of the film such as sliding property, thermal conductivity, conductivity, corona resistance, and loop hardness. The filler to be added is not particularly limited, and examples thereof include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

The particle diameter of the filler is not particularly limited, and may be determined according to the characteristics of the film to be modified and the type of filler to be added. The average particle diameter may be 0.05 to 20 µm, 0.1 to 10 µm, 0.1 to 5 µm, or 0.1 to 3 µm. In the present specification, the average particle diameter may be an average particle diameter measured according to D50 particle size analysis unless otherwise specified.

In the present application, by adjusting the particle diameter range, the modification effect may be sufficiently maintained, and the surface properties may not be impaired and the mechanical properties may not be deteriorated.

In addition, the present application is not particularly limited to the amount of the filler added, and may be determined by film properties to be modified or the particle diameter of the filler. In the present application, the amount of the filler added may be 0.01 to 10 parts by weight, 0.01 to 5 parts by weight, or 0.02 to 1 part by weight based on 100 parts by weight of the polyimide resin. According to the present application, by adjusting the content, the mechanical properties of the film may not be damaged while sufficiently maintaining the modifying effect of the filler.

The method of adding the filler is not particularly limited, and a method known in the same industry may be used.

In one specific example, the polyimide precursor composition may contain 10 to 15% by weight of solids based on the total weight.

In the present application, by controlling the solid content of the polyimide precursor composition, it is possible to prevent an increase in manufacturing cost and process time required to remove a large amount of solvent during the curing process while controlling viscosity increase.

On the other hand, in the preparation of a polyamic acid solution, for example, a method of polymerizing by adding the total amount of the diamine monomer into a solvent, and then adding the dianhydride monomer to be substantially equimolar or excess with the diamine monomer, or the total amount of the dianhydride monomer into a solvent. Into, and then, a diamine monomer is added so as to be substantially equimolar or excessive with the dianhydride monomer to perform polymerization.

As described above, the polyamic acid solution polymerized so that the diamine monomer or the dianhydride monomer is substantially equimolar or excessive is left standing during the process of applying the polyamic acid on the support or thawed and left at room temperature for a long time before use. If the viscosity of the polyamic acid changes during the process, a problem in which the thickness of the target polyimide film changes may occur. However, the polyimide precursor composition according to the present application may exhibit excellent dimensional stability and storage stability even after the above application.

In one example, the polyimide precursor composition has a viscosity change rate defined by Formula 1 below -10 to +10%, -9 to 9%, -8 to 8% -7 to 7%, -5 to 5%,- 3 to 3% or -1.5 to 1.5%.

[Equation 1]

Viscosity change rate = (2nd viscosity-1st viscosity) / 1st viscosity × 100

The first viscosity is a viscosity measured by a Brookfield viscometer on the RV-7 spindle under conditions of 23° C. and a rotation speed of 0.5 rpm at an arbitrary point in time after the polyimide precursor composition is prepared, and the second viscosity is After heating the polyimide precursor composition at any one temperature of 62 to 100° C. for any one hour of 30 minutes to 5 hours at any one point after 7 days from the first viscosity measurement point, a temperature of 23° C. and 0.5 This is the viscosity measured with a Brookfield viscometer on the RV-7 spindle under the condition of the rotational speed of rpm.

Since the change in the viscosity of the polyimide precursor composition means that the polyimide precursor composition is denatured, it can be understood as an index indicating the degree of modification of the polyimide precursor composition.

Conventional polyimic acid shows a change in viscosity exceeding ±300 cP when stored at room temperature for about 7 days, which means that a considerable degree of denaturation has occurred in the polyamic acid. It can be difficult to implement a mid film.

The present application also relates to a method of preparing a polyimide precursor composition. The manufacturing method may be a method of manufacturing the above-described polyimide precursor composition.

The method for preparing a polyimide precursor composition of the present application may include a step of polymerizing a diamine monomer and a dianhydride monomer to prepare a polyamic acid, followed by heating. As described above, the polyimide precursor composition may undergo a side reaction after a certain time. However, the polyimide precursor composition having a specific bond dissociation energy binding unit according to the present application may semi-permanently provide a desired polyimide precursor composition through a step of heating after a predetermined time. The heating step may be different from the imidization curing step.

In one example, the heating step may be performed 3 days after polymerization of the diamine monomer and the dianhydride monomer. In the above, after polymerization of the diamine monomer and the dianhydride monomer, when a certain side reaction proceeds, that is, after a certain time, heating may proceed, and the time is not particularly limited, but after 3 days, 3 to 30 days, 4 It may be 1 to 13 days, 5 to 12 days, or 6 to 10 days. The polyimide precursor composition subjected to constant heating may be provided as a polyimide having excellent dimensional stability as unreacted materials are minimized when imidization is performed thereafter.

The heating step is not necessarily limited to the time. In the heating step, after polymerization of the diamine monomer and the dianhydride monomer, heating may be performed when the viscosity of the polyimide precursor composition changes by 5% or more. The viscosity change may be a change in viscosity at an arbitrary point in time, and for example, heating may be performed when the viscosity changes by 1% or more from an arbitrary point in time (right after polymerization). The rate of change is not particularly limited, and may be any one of 1% or more and 30% or less, and the present application may proceed with heating at the time point.

In one example, the heating may be performed within a range of 62 to 100°C. The temperature range is not particularly limited, but its lower limit may be 63°C, 64°C, 65°C, 66°C, 68°C, 73°C or 75°C. Further, the upper limit may be, for example, 95°C, 90°C, 88°C, 83°C or 75°C. The present application may secure storage stability within the above temperature range, particularly for a precursor composition having a binding unit of the aforementioned bond dissociation energy.

In addition, in one example, the heating step may be performed for 30 minutes to 5 hours. The heating time is not particularly limited, but its lower limit may be 40 minutes, 45 minutes, 50 minutes, 55 minutes or 90 minutes. In addition, the upper limit may be, for example, 4 hours, 3 hours, 150 minutes or 100 minutes. The present application can minimize unreacted substances and secure storage stability of the precursor composition within the heating time range.

The present application also relates to a polyimide that is a cured product of the polyimide precursor composition. In one example, the polyimide may be a cured product of the precursor composition prepared by the method for preparing the polyimide precursor composition described above. The polyimide may be a polyimide film or sheet in the form of a film or sheet.

The polyimide may have a coefficient of thermal expansion (CTE) of 15 ppm/℃ or less, 13 ppm/℃ or less, 10 ppm/℃ or less, or 5 ppm/℃ or less. The lower limit is not particularly limited, but may be 0 ppm/°C or 2 ppm/°C. The CTE may be measured at elevated or lower temperature from 100°C to 350°C, for example. In the present application, by controlling the physical properties of the polyimide, it is possible to implement excellent adhesion while maintaining mechanical properties such as excellent strength, chemical resistance, weather resistance, and heat resistance of the existing polyimide.

In addition, the polyimide may have a light transmittance of 55% or more, 60% or more, 61% or more, 62.5% or more, 64% or more, 65% or more, or 67.5% or more at 550 nm. The upper limit of the light transmittance is not particularly limited, but may be 100% or less, 90% or less, or 80% or less.

In one example, the present application relates to a method of manufacturing a polyimide film. The present application comprises the steps of preparing a gel film by forming a film of the polyimide precursor composition on a support and drying it; And it may provide a method for producing a polyimide film comprising the step of curing the gel film.

Specifically, for a method of imidizing the above polyimide precursor composition to prepare a polyimide film, a conventionally known method may be used.

Specific methods of such imidization include thermal imidation, chemical imidation, or a complex imidization method in which the thermal imidation and chemical imidation are used in combination, and the following non-limiting examples are given. It will be described in more detail through.

The present application provides a polyimide precursor composition capable of securing storage stability and dimensional stability after curing for a polyimide precursor composition requiring storage or storage for a certain period of time, and a method of manufacturing the same.

Hereinafter, the present invention will be described in more detail through examples according to the present invention and comparative examples not according to the present invention, but the scope of the present invention is not limited by the examples presented below.

Example 1

N-methyl-pyrrolidone (NMP) was introduced into a 500 ml reactor equipped with a stirrer and a nitrogen injection and discharge pipe, and the temperature of the reactor was set to 30°C. As a diamine monomer, 1,4-diaminobenzene ( PPD), biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) were added as dianhydride monomers to confirm that they were completely dissolved. After the temperature was raised to 40° C. in a nitrogen atmosphere and stirring was continued for 120 minutes while heating, a polyamic acid solution having a viscosity of 7,000 cP at 23° C. was prepared.

Then, stirring was continued for 2 hours while heating by raising the temperature to 80° C. in a nitrogen atmosphere, and then cooled to 23° C. to show a viscosity of 5,100 cP, and a diamine monomer and a dianhydride monomer were included as shown in Table 1 below. The following polyimide precursor composition was prepared.

After 7 days of preparing the polyimide precursor composition, a post-treatment was performed at 80°C for 1 hour.

Examples 2 to 6 and Comparative Example 1

In Example 1, a polyimide precursor composition was prepared in the same manner as in Example 1, except that the monomer and its content, and post-treatment conditions were changed as shown in Table 1 below, respectively.

	Diamine (mol%)	Dianhydride (mol%)		Post-treatment conditions
	PPD (mol%)	BPDA (mol%)	PMDA (mol%)	Temperature(℃)	time
Example 1	100	50	50	80	1 hours
Example 2	100	50	50	80	2 hours
Example 3	100	100	-	70	1 hours
Example 4	100	100	-	70	2 hours
Example 5	100	50	50	60	1 hours
Example 6	100	50	50	60	2 hours
Comparative Example 1	100	0	100	80	1 hours
Comparative Example 2	100	0	100	-	-
Comparative Example 3	ODA(4,4'-OxyDiAniline) 100%	0	100	80	1 hours

Air bubbles were removed from the polyimide precursor compositions prepared in Examples and Comparative Examples through high-speed rotation of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. Thereafter, a gel film was prepared by drying in a nitrogen atmosphere and at a temperature of 120° C. for 30 minutes, and the gel film was heated to 450° C. at a rate of 2° C./min, heat-treated at 450° C. for 60 minutes, and then until 30° C. The polyimide film was obtained by cooling at a rate of 2° C./min. Thereafter, the polyimide film was removed from the glass substrate by dipping in distilled water. The physical properties of the prepared polyimide film were measured using the following method, and the results are shown in Table 2 below.

Experimental Example 1-Thickness

The thickness of the prepared polyimide film was measured.

Experimental Example 2-Viscosity Measurement

For the polyimide precursor compositions prepared in Examples and Comparative Examples, a Brookfield viscometer (RVDV-II+P) was measured twice at 50 rpm using a 7 scandal at 25°C, and the average value was calculated to measure the first viscosity. I did.

After the viscosity measurement, it was left at room temperature for 7 days. Thereafter, the second viscosity was measured in the same manner after the post-treatment process.

The rate of change of the first viscosity and the second viscosity was calculated. If the rate of change is 5% or less, it may be classified as excellent, if it is 10% or less, it may be classified as normal, and if it is more than 10%, it may be classified as defective.

Experimental Example 3-Pyrolysis temperature (Td)

TA's thermogravimetric analysis Q50 model was used, and the polyimide film was heated to 150°C at a rate of 10 min/°C in a nitrogen atmosphere, and then maintained isothermal for 30 minutes to remove moisture. Thereafter, the temperature was increased to 600° C. at a rate of 10 min/° C., and the temperature at which a weight loss of 1% occurred was measured.

Experimental Example 4-CTE

TA's thermomechanical analyzer Q400 model was used, and a polyimide film was cut into 2 mm in width and 10 mm in length, and then 500 N at room temperature at a rate of 10 °C/min while applying a tension of 0.05 N in a nitrogen atmosphere. After raising the temperature to °C, while cooling at a rate of 10 °C/min again, the slope of the section from 100 °C to 350 °C was measured.

Experimental Example 5-Transmittance

For the polyimide film prepared above, light transmittance at 550 nm was measured using a UV-Vis Spectrometer.

Experimental Example 6-PD (polydispersity)

Polydispersity was measured using Agilent Technologies' HPLC 1260 Infinity II model. Specifically, the polyimide precursor composition was dissolved in a mobile phase NMP solution at a concentration of 1% by weight, and then filtered through a 0.45 μm filter, and then measured. Using PLgel 5 mm Mixed-D as a column, the PD value of the polyimide precursor composition was measured at a flow rate of 0.9 ml/min under the measurement temperature condition of 50°C. Before the measurement, using polystyrene as a molecular weight standard sample, the PD value was calculated by a calibration curve carried out in the same manner as the above measurement conditions.

	Thickness(㎛)	1st viscosity (cP)	Pyrolysis temperature (℃)	CTE(ppm/℃)	PD	Transmittance (%)	Viscosity change rate (%)
Example 1	15.3	5100	575	3.5	1.8	62	+1
Example 2	15.3	5100	570	3.7	1.9	63	+2
Example 3	15	6000	578	4.3	2.0	67	+4
Example 4	15	6000	576	4.5	2.0	68	+4
Example 5	15.3	5100	555	8.4	2.2	57	+8
Example 6	15.3	5100	556	8.4	2.2	58	+8
Comparative Example 1	15.1	4800	550	-2.5	2.3	45	+13
Comparative Example 2	15.1	4800	560	2.0	2.3	50	+15
Comparative Example 3	15	5000	535	32	2.3	66	-15

Claims (19)

1. A polyimide precursor composition comprising a diamine monomer and a dianhydride monomer as a polymerization unit, and a first bonding unit having a bond dissociation energy of 650 KJ/mol or less.
2. The polyimide precursor composition according to claim 1, wherein at least one of a diamine monomer and a dianhydride monomer comprises a monomer including two or more aromatic rings connected by the first bonding unit.
3. The polyimide precursor composition according to claim 2, wherein the first bonding unit further comprises a dissociated diamine monomer or a dianhydride monomer.
4. The diamine according to claim 2, wherein a diamine monomer is polymerized at the terminal, or a dianhydride monomer from which the first binding unit is dissociated is bonded to the diamine monomer polymerized at the terminal, or the first bonding unit is dissociated at the terminal. Polyimide precursor composition to which a monomer is bound.
5. The polyimide precursor composition according to claim 4, wherein, when the diamine monomer is polymerized at the terminal, the amine group of the diamine monomer at the terminal is dissociated from some bonding units prior to formation of an amide bond.
6. The polyimide precursor composition according to claim 1, wherein the polyimide precursor composition has a polydispersity of 2.2 or less after curing.
7. The polyimide precursor composition according to claim 1, wherein the thermal decomposition temperature after curing is 560°C or higher.
8. The polyimide precursor composition according to claim 1, wherein the weight average molecular weight after curing is in the range of 10,000 to 100,000.
9. The polyimide precursor composition according to claim 1, wherein the elongation after curing is 15% or more.
10. The polyimide precursor composition according to claim 1, wherein the viscosity measured with a Brookfield viscometer on the RV-7 spindle at 23° C. and a rotation speed of 0.5 rpm is 10,000 cP or less.
11. The method of claim 1, wherein the diamine monomer is 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene or 4,4 '- A polyimide precursor composition comprising methylenediamine (MDA).
12. The method of claim 1, wherein the dianhydride monomer is pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) or 2,3, A polyimide precursor composition comprising 3',4'-biphenyltetracarboxylic dianhydride (a-BPDA).
13. The polyimide precursor composition according to claim 1, wherein the viscosity change rate defined by the following Equation 1 is -10 to +10%:

    [Equation 1]

    Viscosity change rate = (2nd viscosity-1st viscosity) / 1st viscosity X 100

    The first viscosity is a viscosity measured by a Brookfield viscometer on the RV-7 spindle under conditions of 23° C. and a rotation speed of 0.5 rpm at an arbitrary point in time after the polyimide precursor composition is prepared, and the second viscosity is After heating the polyimide precursor composition at any one temperature of 62 to 100° C. for any one hour of 30 minutes to 5 hours at any one point after 7 days from the first viscosity measurement point, a temperature of 23° C. and 0.5 This is the viscosity measured with a Brookfield viscometer on the RV-7 spindle under the condition of the rotational speed of rpm.
14. A method for preparing a polyimide precursor composition according to claim 1, comprising polymerizing a diamine monomer and a dianhydride monomer to prepare a polyamic acid, followed by heating.
15. The method of claim 14, wherein the heating step is performed 3 days after polymerization of the diamine monomer and the dianhydride monomer.
16. 15. The method of claim 14, wherein the heating is performed when the diamine monomer and the dianhydride monomer are polymerized and the viscosity of the polyimide precursor composition is changed by 5% or more.
17. The method of claim 14, wherein the heating step is heated to within the range of 62 to 100°C.
18. The method of claim 14, wherein the heating step is performed for 30 minutes to 5 hours.
19. A polyimide which is a cured product of the polyimide precursor composition of claim 1.