KR102125686B1 - Polyamic acid composition and method for preparing the same - Google Patents

Abstract

The present invention provides a polyamic acid composition comprising a diamine monomer and a dianhydride monomer in a molar ratio of 1:0.98 to 0.99, and satisfying Equation 1 below:
[Equation 1]
|[(V ₁ -V ₂ )/V ₁ ]×100|≤15(%)
In Equation 1,
V ₁ represents the viscosity immediately after forming the polyamic acid composition on the support,
V ₂ represents the viscosity after 1 hour at 25° C. after forming the polyamic acid composition on the support.

Description

Polyamic acid composition, and manufacturing method thereof {POLYAMIC ACID COMPOSITION AND METHOD FOR PREPARING THE SAME}

The present invention relates to a polyamic acid composition having improved storage stability and viscosity stability and a method for manufacturing the same.

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-performance polymer material applicable to a wide range of industries such as electronics, communications, and optics due to its excellent electrical properties such as insulation properties and low dielectric constant.

Recently, as various electronic devices have become thinner, lighter, and smaller, many studies have been conducted to use a light and flexible thin polyimide film as a display substrate that can replace an insulating material of 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 on 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 can be hydrolyzed as it reacts with an adjacent amine group, resulting in poor storage stability and viscosity stability of the polyamic acid composition containing the same. Is known. It is also known that this phenomenon is more pronounced at room temperature or higher than at a low temperature.

When the storage stability and the viscosity stability of the polyamic acid composition are poor, the viscosity may change greatly during the process or during a long-time thawing process, and accordingly, the application and imidation of the polyamic acid composition may proceed unstable. In addition, when the viscosity of the polyamic acid is changed, deterioration of the mechanical and thermal properties of the polyimide film may be caused.

The deterioration of the thermal properties of the double polyimide film can be particularly negative for the manufacture of display substrates involving high temperature processes.

For example, in the case of an organic light emitting diode (OLED) using a low temperature polysilane (LTPS) process, a process temperature of 400° C. or higher may be formed, and even at high temperatures, even polyimide having excellent heat resistance may be thermally decomposed. The thermal properties of the polyimide film can be said to be a very important factor in realizing a display substrate.

In addition, in the case of the method for producing a polyimide film as described above, a process of applying a polyamic acid on a support, followed by imidization to prepare a film in the form of a film, and a process of peeling it from the support, sequentially perform a number of poly It is common to produce a mid film, and in particular, when the viscosity of the polyamic acid changes in a state left in the process of applying the polyamic acid on a support, a problem in which the thickness of the targeted polyimide film changes may occur.

Accordingly, there is a high need for a polyamic acid excellent in storage stability at room temperature and viscosity stability in the process, and a polyimide film excellent in mechanical and thermal properties.

An object of the present invention is to provide a method for preparing a polyamic acid composition having excellent storage stability at room temperature and viscosity stability during a process of applying polyamic acid on a support, and a polyamic acid composition prepared using the same.

At the same time, the polyimide film prepared from the polyamic acid composition of the present invention has a thermal decomposition temperature (Td) of 1% by weight or more, 560°C or more, a thermal expansion coefficient of 5 ppm/°C or less, an elongation of 15% or more, and tensile strength. Is 350 MPa or more, and may have a thickness of 10 to 20 μm. The polyimide film has an advantage of satisfying mechanical and thermal properties required for a flexible circuit board or a display board.

Accordingly, the present invention has a practical purpose in providing specific examples thereof.

In order to achieve the above object,

The present invention provides a polyamic acid composition comprising a diamine monomer and a dianhydride monomer in a molar ratio of 1:0.98 to 0.99, and satisfying Equation 1 below:

[Equation 1]

|[(V ₁ -V ₂ )/V ₁ ]×100|≤15(%)

In Equation 1,

V ₁ represents the viscosity immediately after forming the polyamic acid composition on the support,

V ₂ represents the viscosity after 1 hour at 25° C. after forming the polyamic acid composition on the support.

The present invention also, an organic solvent; And mixing the diamine monomer and the dianhydride monomer at a molar ratio of 1:0.98 to 0.99 to polymerize the mixture.

The present invention also, the step of forming a polyamic acid composition on a support and dried to produce a gel film; And it provides a method for producing a polyimide film comprising the step of curing the gel film.

The present invention also provides a polyimide film comprising a cured product of the polyamic acid composition.

The present invention also provides an electronic device comprising the polyimide film.

As described above, the method for preparing the polyamic acid composition according to the present invention comprises the steps of preparing a polyamic acid composition by polymerizing a diamine monomer and a dianhydride monomer in an organic solvent at a molar ratio of 1:0.98 to 0.99. The effect of improving the viscosity stability during the process of coating on the support of the mixed acid composition can be exhibited.

At the same time, the manufacturing method according to the present invention includes the step of aging by heating the polyamic acid composition to 55 to 85° C. and stirring for 1 to 4 hours, thereby ensuring storage stability at the normal temperature of the polyamic acid composition itself. It can exert an effect of improving.

In addition, the polyimide film manufactured as described above has excellent mechanical and thermal properties, and can be preferably applied to a flexible circuit board or a display substrate.

The present invention can be variously changed and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In the present invention, terms such as "comprises" or "have" are intended to indicate that there are features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

In the present invention, "dianhydride (dianhydride)" is intended to include its precursor or derivative, which may not technically be dianhydride, but nevertheless reacts with diamine to form a polyamic acid. And this polyamic acid can be converted back to polyimide.

In the present invention, “diamine” 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 polyamic acids again Can be converted to polyimide.

In the present invention, when an amount, concentration, or other value or parameter is given as an enumeration of a range, a preferred range, or a preferred upper and lower limit, any upper limit of any pair of any pair, regardless of whether the ranges are disclosed separately. Or it should be understood to specifically disclose all ranges formed of preferred values and any lower range limits or preferred values.

When a range of numerical values is referred to herein, unless stated otherwise, that range is intended to include the endpoints 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.

Hereinafter, the present invention will be described in detail.

The polyamic acid composition according to the present invention includes a diamine monomer and a dianhydride monomer in a molar ratio of 1:0.98 to 0.99, and satisfies Equation 1 below:

[Equation 1]

|[(V ₁ -V ₂ )/V ₁ ]×100|≤15(%)

In Equation 1,

V ₁ represents the viscosity immediately after forming the polyamic acid composition on the support,

V ₂ represents the viscosity after 1 hour at 25° C. after forming the polyamic acid composition on the support.

As one specific example, the polyamic acid composition may include a diamine monomer and a dianhydride monomer in a molar ratio of 1:0.98 or 1:0.99.

Equation 1 shows the rate of change of viscosity after 1 hour at 25° C. after film formation immediately after film formation of the polyamic acid composition on a support, of |[(V ₁ -V ₂ )/V ₁ ]×100| The value represents the rate of change in viscosity (%), and the rate of change in viscosity may be 0 to 15%, 1 to 15%, 1 to 10%, 1 to 5%, 5 to 15%, or 10 to 15%.

In the case of a conventional polyamic acid composition, the viscosity immediately after film formation on the support and the rate of change according to the viscosity after 1 hour at 25° C. after film formation exceed ±15%, thereby causing the polyamic acid composition to remain in the process. Variation in viscosity of the target may cause a problem that the target thickness of the polyimide film is not realized.

On the other hand, the polyamic acid composition of the present invention, the viscosity change according to the above formula is not as large as the above range, it can be seen that the film forming viscosity stability during the process is very excellent.

The polyamic acid composition according to the present invention is characterized by satisfying the following Equation 2:

[Equation 2]

|V ₃ -V ₄ |≤200(cP)

In Equation 2,

V ₃ represents the viscosity at any point in time at 25° C. of the polyamic acid composition,

V ₄ represents the viscosity after 7 days have elapsed from the above arbitrary time point at 25°C of the polyamic acid composition.

Equation 2 shows the viscosity change after 7 days from any time point and any time point at 25° C. of the polyamic acid composition, and |V ₃ -V ₄ | shows the viscosity change of the polyamic acid composition, and the viscosity The change can be 0 to 200 cP, 1 to 200 cP, 1 to 150 cP, 1 to 100 cP, 1 to 50 cP, 50 to 200 cP, 100 to 200 cP, or 150 to 200 cP.

Since the change in viscosity of the polyamic acid composition means that denaturation has occurred in the polyamic acid composition, it can be understood as an index indicating the degree of modification of the polyamic acid composition.

Conventional polyimic acid exhibits a viscosity change in excess of ±300 cP when stored for about 7 days at room temperature, which means that a significant degree of degeneration has occurred in the polyamic acid, and the storage stability is poor, resulting in excellent physical properties of polyimide. Films can be difficult to implement.

On the other hand, it can be seen that the polyamic acid composition according to the present invention has a very excellent storage stability at room temperature with a viscosity change of ±200 cP or less.

It can be understood that the polyamic acid in the polyamic acid composition is a result of adjusting the ratio of the weight average molecular weight to the number average molecular weight (poly dispersity index) to 1,3 to 2,2, 1.5 to 2.0, or 1.5 to 1.8. have.

Specifically, the ratio of the weight-average molecular weight to the number-average molecular weight of the polyamic acid is adjusted as described above, which means that the distribution of molecular weight is formed narrowly, which produces relatively low oligomers of low molecular weight present in the polyamic acid composition. It can be understood as. That is, since it means that the number of low molecular weight oligomers capable of causing a viscosity change through an additional polymerization reaction at room temperature is small, the polyamic acid composition according to the present invention can exhibit an effect of improving storage stability at room temperature.

The V ₃ may be 3,000 to 8,000 cP, 3,000 to 6,000 cP, 3,000 to 4,000 cP, or 5,000 to 8,000 cP, and in one specific example, when V ₃ is 3,000 to 8,000 cP, V ₄ is 3,200 to 8,200 cP. By having V ₃ in the above range, the polyamic acid composition has an advantage of easy handling in terms of fluidity, and may be advantageous in film formation.

For example, when the viscosity of V ₃ is greater than 8,000 cP, the process cost is increased because a higher pressure must be applied by friction with the pipe when the polyamic acid composition is moved through the pipe during the polyimide manufacturing process. Handling may be deteriorated. In addition, the higher the viscosity, the more time and cost may be required for the mixing process. On the other hand, when the viscosity of the V ₃ is less than 3,000 cP, a problem that an increase in manufacturing cost and process time may occur as a large amount of solvent must be removed during the curing process.

The polyamic acid composition may contain 10 to 15% by weight of solids based on the total weight. As one specific example, the polyamic acid composition may include 10 to 13% by weight, 10 to 11% by weight, or 13 to 15% by weight of solids based on the total weight.

When the solid content of the polyamic acid composition is more than 15% by weight, the viscosity of the polyamic acid composition is increased to reduce storage stability, and when the solid content of the polyamic acid composition is less than 10% by weight, a large amount in the curing process As it is necessary to remove the solvent, the manufacturing cost and process time may increase.

The dianhydride monomer may be an aromatic tetracarboxylic dianhydride, and the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride (or PMDA), 3,3',4,4'-bi Phenyltetracarboxylic 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'-benzophenonetetracarboxylic 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 (trimeric monoester acid anhydride), p-biphenylenebis (trimeric monoester acid anhydride), m-terphenyl-3,4 ,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxy Phenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2 ,2-bis[(3,4-dicarboxy phenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalene Tetracarboxylic dianhydride, or 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride. Specifically, the dianhydride monomers are pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3' ,4'-Biphenyltetracarboxylic dianhydride (a-BPDA).

In addition, the diamine monomer is an aromatic diamine, and may be exemplified by classifying as follows, and may include one or more selected from the group consisting of the following materials.

1) 1,4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzo Diamine having one benzene nucleus in the structure, such as diacid (or DABA), etc., which has a relatively rigid structure in diamine;

2) Diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or oxidianiline, ODA), 3,4'-diaminodiphenyl ether, and 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 -Aminophenyl sulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-bis [2-(4-aminophenyl)isopropyl] diamine having three benzene nuclei in structure, such as 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-aminophenoxy)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., structure Diamine with four phase benzene nuclei.

Specifically, the diamine monomers are 4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene and 3,5-diaminobenzo. It may include one or more selected from the group consisting of Ixid (DABA).

In addition, the present invention provides a method for preparing the polyamic acid composition. Specifically, the method for preparing the polyamic acid composition according to the present invention includes an organic solvent; And mixing the diamine monomer and the dianhydride monomer at a molar ratio of 1:0.98 to 0.99 to polymerize the mixture.

In one specific example, the polymerization reaction may be performed in a temperature range of 10 to 50 °C, 10 to 40 °C, 10 to 30 °C, 20 to 50 °C, 30 to 50 °C, or 20 to 40 °C.

In one specific example, after the polymerization reaction may include the step of aging (aging) the polyamic acid composition at 55 to 85 ℃, the aging may be performed for 1 to 4 hours. The aging may exert an effect of improving storage stability at room temperature of the polyamic acid composition, as described below.

In one specific example, the aging is a solution after polymerization at 55 to 85 ℃, 55 to 75 ℃, 55 to 65 ℃, 65 to 85 ℃, or 60 to 80 ℃, 1 to 4 hours, 1 to 3 hours, It may include a step of stirring for 1 to 2 hours, or 2 to 3 hours, specifically, may include the step of aging by stirring the solution for 2 to 3 hours at 60 to 80 ℃ after the polymerization. When the temperature and the stirring time for the aging are out of the above range, the storage stability of the polyamic acid composition to be prepared may be lowered, and in particular, when the temperature of the temperature is too high, the solid content may be changed due to evaporation of the solvent. It may cause deterioration of the mechanical and thermal properties of the polyimide film produced.

In one specific example, the method for preparing a polyamic acid composition according to the present invention is after the aging step, the aged polyamic acid composition is 10 to 30°C, 10 to 25°C, 10 to 20°C, 15 to 25°C, or It may further include a step of cooling to 20 to 30 ℃, the cooling method is not particularly limited, and may include natural cooling as an example.

The organic solvent used in the present invention is not particularly limited as long as it is an organic solvent in which the polyamic acid can be dissolved, and as an example, may include an aprotic polar solvent. As an example, the aprotic polar solvent is an amide solvent such as N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), p-chlorophenol, o-chlorophenol It may include one or more selected from the group consisting of phenol-based solvents, such as N-methyl-pyrrolidone (NMP), gamma-tyrolactone (GBL), and digrime.

The aprotic polar solvent may adjust the solubility of polyamic acid by using auxiliary solvents such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, and water.

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

On the other hand, the manufacturing method of the polyamic acid composition according to the present invention may further include a filler added 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 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 film properties to be modified and the type of the filler to be added. As one specific example, the average particle diameter of the filler may be 0.05 to 20 μm, 0.1 to 10 μm, 0.1 to 5 μm, or 0.1 to 3 μm. For example, if the average particle diameter of the filler is less than 0.05 μm, a modification effect is unlikely to appear, and if the average particle diameter exceeds 20 μm, surface properties may be significantly impaired or mechanical properties may be significantly deteriorated.

In addition, the amount of the filler to be added is not particularly limited, and may be determined by film properties to be modified, particle size of the filler, and the like. As one specific example, the addition amount of the filler 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. For example, if the amount of the filler added is less than 0.01 part by weight, the modification effect by the filler is difficult to appear, and if the amount of the filler added exceeds 20 parts by weight, the mechanical properties of the film may be significantly impaired. The method for adding the filler is not particularly limited, and any known method can be used.

The polyamic acid composition according to the present invention improves the storage stability at room temperature of the polyamic acid composition itself through the manufacturing method including the aging step, and the viscosity change according to the above formula is ±200 cP, and the storage stability at room temperature is very excellent. You can see that

The ratio of the weight average molecular weight to the number average molecular weight of the polyamic acid contained in the polyamic acid composition is adjusted to 1,3 to 2,2, and specifically 1.5 to 2.0 by aging in the specific temperature range. It can be understood as the result.

On the other hand, in the preparation of a conventional polyamic acid composition, for example, the total amount of diamine monomers is added to the solvent, and then the dianhydride monomer is added to the diamine monomer to be substantially equimolar or in excess, and polymerization is performed. Is added in a solvent, and then a diamine monomer is added so as to be substantially equimolar or in excess with the dianhydride monomer, followed by polymerization.

As described above, the polyamic acid composition polymerized such that the diamine monomer or the dianhydride monomer is substantially equimolar or excessive is left in the state of being left in the process of applying the polyamic acid described above on the support or thawed at room temperature for a long time before use. When the viscosity of the polyamic acid changes in the process, a problem may occur in which the thickness of the targeted polyimide film is changed.

On the other hand, the present invention will be demonstrated in detail below, but a polyamic acid composition is prepared by polymerizing a diamine monomer and a dianhydride monomer in an organic solvent at a molar ratio of 1:0.98 to 0.99, and polymerized at a specific molar ratio as described above. Unlike the case where the polyamic acid composition of the present invention is polymerized in a molar ratio outside the scope of the present invention, it is left in the process of applying the polyamic acid composition on a support, or even after being thawed at room temperature for a long time before use, and its viscosity It can exhibit the effect of suppressing change.

Furthermore, the present invention comprises the steps of forming a polyamic acid composition on a support and drying the gel film; And it may provide a method for producing a polyimide film comprising the step of curing the gel film.

Specifically, for the method for producing a polyimide film by imidizing the polyamic acid composition described above, a conventionally known method can be used.

Specific examples of the imidization method include a thermal imidization method, a chemical imidization method, or a complex imidization method using a combination of the thermal imidization method and a chemical imidization method, and the following non-limiting examples This will be described in more detail.

<Thermal imidization method>

The thermal imidization method is a method of excluding chemical catalysts and inducing an imidization reaction with a heat source such as hot air or an infrared dryer.

Drying the polyamic acid composition to form a gel film; And heat-treating the gel film to obtain a polyimide film.

Here, 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 the process of forming the gel film, the polyamic acid composition is cast in a film form on a support such as a glass plate, aluminum foil, endless stainless belt, or stainless drum, and then the polyamic acid composition on the support is 50 to 200°C. , Specifically, may be dried at a variable temperature in the range of 80 to 150°C.

Accordingly, a gel film may be formed by partial curing and/or drying of the polyamic acid composition, and the formed gel film may be peeled off from the support to obtain a gel film.

In some cases, a process of stretching the gel film may be performed in order to control the thickness and size of the polyimide film obtained in the subsequent heat treatment process and to improve the orientation, and the stretching is performed in the machine transport direction (MD) and the machine transport direction. It may be performed in at least one of the lateral direction for (TD).

The gel film thus obtained may be fixed to a tenter and then subjected to a step of curing in a temperature range of 30 to 500°C. Specifically, the curing is first heat-treated at 30 to 50°C for 5 to 10 minutes. step; Performing a second heat treatment at 180 to 220° C. for 25 to 35 minutes; And a third heat treatment at 440 to 480°C for 35 to 45 minutes to sequentially heat at a variable temperature to remove water, residual solvent, and the like remaining in the gel film, and imidize almost all remaining amic acid groups. Thus, the polyimide film of the present invention can be obtained.

At this time, the first heat treatment to the third heat treatment may be heated at any one or more heating rates selected from the range of 1 to 10 ℃ / min. For example, the heating rate may be 1 to 8°C/min, 1 to 5°C/min, 3 to 10°C/min, or 5 to 10°C/min.

In some cases, the polyimide film obtained as described above may be heat-finished at a temperature of 300 to 600° C. for 5 to 400 seconds to further harden the polyimide film, and internal stress that may remain in the obtained polyimide film It can also be done under a given tension in order to mitigate this.

<Chemical imidation method>

The chemical imidization method is a method of promoting imidization of an amic acid group by adding a dehydrating agent and/or an imidizing agent to the polyamic acid composition.

Here, the term “dehydrating agent” refers to a substance that promotes a cyclization reaction through dehydration of a polyamic acid, and as a non-limiting example, an aliphatic acid anhydride, an aromatic acid anhydride, N,N' -Dialkyl carbodiimide, lower halogenated aliphatic, lower halogenated 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 include acetic anhydride (AA), propionic 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 polyamic acid, and for example, imine-based components such as aliphatic tertiary amine, aromatic tertiary amine, and heterocyclic tertiary amine Can be Specifically, a heterocyclic tertiary amine may be included from the viewpoint of reactivity as a catalyst. Non-limiting examples of heterocyclic tertiary amines may include one or more selected from the group consisting of quinoline, isoquinoline, β-picoline (BP), and pyridine.

The amount of the dehydrating agent may be 0.5 to 5.0 moles, 0.5 to 3 moles, 0.5 to 1.0 moles, 1.0 to 4.0 moles, or 2.0 to 4.0 moles per 1 mole of the amic acid group in the polyamic acid. The amount of the imidizing agent added may be 0.05 to 2 mol, 0.05 to 1 mol, 0.2 mol to 1 mol, or 0.5 to 1 mol with respect to 1 mol of the amic acid group in the polyamic acid.

When the dehydrating agent and the imidizing agent are less than 0.5 mol and 0.05 mol, respectively, with respect to 1 mol of the amic acid group in the polyamic acid, chemical imidization is insufficient, cracks may be formed in the polyimide film to be produced, and the mechanical strength of the film is also reduced Can be. In addition, if these addition amounts are more than 5.0 mol and 2 mol, respectively, with respect to 1 mol of the amic acid group in the polyamic acid, imidization may proceed excessively rapidly, in which case, it is difficult to cast in the form of a film or the prepared polyimide film is brittle. There is a problem of exhibiting (brittle) characteristics.

<Composite imidization method>

In conjunction with the chemical imidization method described above, a complex imidization method in which a thermal imidization method is further performed can be used for the production of a polyimide film.

Specifically, the complex imidization method includes a chemical imidization method in which a dehydrating agent and/or an imidizing agent is added to the polyamic acid composition at a low temperature; And drying the polyamic acid composition to form a gel film, and a heat imidization process of heat-treating the gel film.

When performing the chemical imidization process, the type and amount of the dehydrating agent and the imidizing agent may be appropriately selected as described in the previous chemical imidization method.

In the process of forming the gel film, a polyamic acid 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 thereafter the support. The polyamic acid composition on top is dried at variable temperatures ranging from 50 to 180°C or 80 to 180°C. In this process, chemical converting agents and/or imidizing agents can act as catalysts to rapidly convert the amic acid groups to imide groups.

In some cases, a process of stretching the gel film may be performed in order to control the thickness and size of the polyimide film obtained in the subsequent heat treatment process and to improve the orientation, and the stretching is performed in the machine transport direction (MD) and the machine transport direction. It may be performed in at least one of the lateral direction for (TD).

The gel film thus obtained is fixed to a tenter and then heat-treated at a variable temperature described above to remove water, catalyst, residual solvent, and the like remaining in the gel film, and imidize most of the remaining amic acid groups. The polyimide film of the present invention can be obtained. 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 heat-finished at a temperature of 400 to 500° C. for 5 to 400 seconds to further harden the polyimide film, and may generate internal stress that may remain in the obtained polyimide film. It can also be done under certain tension to relieve.

The present invention can also provide a polyimide film produced by the method for producing the polyimide film.

The polyimide film of the present invention manufactured according to the above manufacturing method has a thermal decomposition temperature (Td) of 1% by weight or more, 560°C or more, a thermal expansion coefficient of 5 ppm/°C or less, an elongation of 15% or more, and tensile strength. Is 350 MPa or more, and the thickness may be 10 to 20 μm.

The present invention can also provide an electronic device including the polyimide film. The electronic device may include a flexible circuit board or a display board.

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

<Example 1>

After injecting nitrogen into a 500 mL reactor equipped with a stirrer and a nitrogen injection/discharge tube, NMP was introduced and the temperature of the reactor was set to 30°C, followed by PPD as a diamine monomer, BPDA and PMDA as a dianhydride monomer, and completely dissolved. To confirm that. After heating at 40° C. under a nitrogen atmosphere and stirring was continued for 120 minutes, a polyamic acid composition having a viscosity at 23° C. of 7,000 cP was prepared.

Icer, the temperature was raised to 80° C. under a nitrogen atmosphere, and stirring was continued for 2 hours while heating, and then cooled to 23° C. to show a viscosity (V ₃ ) of 4,500 cP. A polyamic acid composition comprising 1 was prepared.

<Examples 2 to 7 and Comparative Examples 1 to 5>

In Example 1, a polyamic acid composition was prepared in the same manner as in Example 1, except that the monomer and its content, whether aging, the aging temperature, and the aging time were changed as shown in Table 1 below.

<Experimental Example 1: Storage stability evaluation>

The polyamic acid compositions prepared in Examples 1 to 7 and Comparative Examples 1 to 5 were left at room temperature (25° C.) for 7 days. Thereafter, the viscosity (V ₄ ) was measured, and the viscosity change was calculated according to Equation 2 below, and the results are shown in Table 2 below.

[Equation 2]

|V ₃ -V ₄ |≤200(cP)

In Equation 2,

V ₃ represents the viscosity at any point in time at 25° C. of the polyamic acid composition,

V ₄ represents the viscosity after 7 days have elapsed from the above arbitrary time point at 25°C of the polyamic acid composition.

For the viscosity measurement, the average value was measured by measuring the Brookfield viscometer (RVDV-II+P) twice at 50 rpm using scandal 7 times at 25°C.

<Experimental Example 2: Evaluation of viscosity stability>

In the polyamic acid compositions prepared in Examples 1 to 7 and Comparative Examples 1 to 5, air bubbles were removed through high-speed rotation of 1,500 rpm or more. Thereafter, the defoamed polyamic acid composition was applied to the glass substrate using a spin coater.

Immediately after application, the viscosity (V ₁ ) of the polyamic acid composition was measured. Thereafter, the viscosity (V ₂ ) of the polyamic acid composition was measured at a temperature of 25° C. for 1 hour, and the rate of change of viscosity was calculated according to Equation 1 below, and the results are shown in Table 3 below.

[Equation 1]

|[(V ₁ -V ₂ )/V ₁ ]×100|≤15(%)

In Equation 1,

V ₁ represents the viscosity immediately after forming the polyamic acid composition on the support,

V ₂ represents the viscosity after 1 hour at 25° C. after forming the polyamic acid composition on the support.

Referring to Tables 2 and 3, in the case of the examples prepared by the production method of the present invention, it can be confirmed that both storage stability at room temperature and viscosity stability during the process are excellent. On the other hand, it was confirmed that the comparative examples did not satisfy at least one of storage stability or viscosity stability.

<Experimental Example 3: Property evaluation>

In the polyamic acid compositions prepared in Examples 1 to 7 and Comparative Examples 1 to 5, air bubbles were removed through high-speed rotation of 1,500 rpm or more. Thereafter, the defoamed polyamic acid composition was applied to the glass substrate using a spin coater. Then, under a nitrogen atmosphere and dried at a temperature of 120° C. for 30 minutes, a gel film was prepared, and the gel film was heated to a rate of 2° C./min to 450° C., heat-treated at 450° C. for 60 minutes, to 30° C. Cooling at a rate of 2°C/min yielded a polyimide film.

Thereafter, the polyimide film was peeled from the glass substrate by dipping in distilled water. The thickness of the prepared polyimide film was 10 μm. The physical properties of the prepared polyimide film were measured using the following method, and the results are shown in Table 4 below.

(1) Coefficient of thermal expansion ( CTE )

A TA thermomechanical analyzer Q400 model was used, and the polyimide film was cut to a width of 2 mm and a length of 10 mm, and then subjected to a tension of 0.05 N under a nitrogen atmosphere, at a rate of 10°C/min, 500 at room temperature. After heating up to ℃ ℃, while cooling at a rate of 10 ℃ / min was measured the slope of the section from 100 ℃ to 350 ℃.

(2) Elongation

After the polyimide film was cut to a width of 10 mm and a length of 40 mm, elongation was measured by an ASTM D-882 method using Instron5564 UTM equipment manufactured by Instron.

(3) 1 Wt% Pyrolysis temperature( TD )

A TA company thermogravimetric analysis Q50 model was used, and the polyimide film was heated to 150° C. at a rate of 10 min/° C. under a nitrogen atmosphere to maintain isotherm for 30 minutes to remove moisture. Thereafter, the temperature was raised to 600°C at a rate of 10 min/°C, and the temperature at which 1% weight loss occurred was measured.

(4) Tensile strength

After the polyimide film was cut to a width of 10 mm and a length of 40 mm, tensile strength was measured by ASTM D-882 method using Instron5564 UTM equipment of Instron. The cross head speed at this time was measured under the condition of 5 mm/min.

Referring to Table 4, it can be seen that in the case of the examples produced by the manufacturing method of the present invention, both mechanical and thermal properties are excellent. On the other hand, it can be confirmed that the comparative examples do not satisfy at least one of mechanical or thermal properties.

On the other hand, in Comparative Example 3 prepared from a polyamic acid composition obtained by polymerizing a diamine monomer and a dianhydride monomer in a 1:1 molar ratio, physical properties may be confirmed to be excellent, but as described above, the viscosity stability of the polyamic acid composition is It can be confirmed that it is not excellent.

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

Claims (18)

Diamine monomer, dianhydride monomer and organic solvent,
The diamine monomer and the dianhydride monomer are contained in a molar ratio of 1:0.98 to 0.99,
As a polyamic acid composition satisfying the following equation (1),
The polyamic acid composition in the polyamic acid composition has a polyamic acid composition in which the ratio of the weight average molecular weight to the number average molecular weight (poly dispersity index) is 1.5 to 2.0:
[Equation 1]
|[(V ₁ -V ₂ )/V ₁ ]×100|≤15(%)
In Equation 1,
V ₁ represents the viscosity immediately after forming the polyamic acid composition on the support,
V ₂ represents the viscosity after 1 hour at 25° C. after forming the polyamic acid composition on the support.
According to claim 1,
The polyamic acid composition is a polyamic acid composition satisfying the following Equation 2:
[Equation 2]
|V ₃ -V ₄ |≤200(cP)
In Equation 2,
V ₃ represents the viscosity at any point in time at 25° C. of the polyamic acid composition,
V ₄ represents the viscosity after 7 days have elapsed from the above arbitrary time point at 25°C of the polyamic acid composition.
According to claim 2,
V ₃ of Equation 2 is a polyamic acid composition of 3,000 to 8,000 cP.
According to claim 1,
The polyamic acid composition is a polyamic acid composition comprising 10 to 15% by weight of solids based on the total weight.
delete According to claim 1,
Diamine monomers are 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene and 3,5-diaminobenzoic acid (DABA) contains at least one selected from the group consisting of,
Dianhydride monomers are pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'- A polyamic acid composition comprising at least one member selected from the group consisting of biphenyltetracarboxylic dianhydride (a-BPDA).
Organic solvents; And mixing the diamine monomer and the dianhydride monomer at a molar ratio of 1:0.98 to 0.99 to polymerize the mixture; And
After the polymerization reaction, the step of aging the polyamic acid composition at 55 to 85 ℃ (aging),
A method for preparing the polyamic acid composition according to claim 1, wherein the ratio of the weight average molecular weight to the number average molecular weight of the polyamic acid contained in the polyamic acid composition is adjusted to 1.5 to 2.0 by the aging step. .
delete The method of claim 7,
Aging is a method for producing a polyamic acid composition performed for 1 to 4 hours.
The method of claim 7,
After the aging step, the method of manufacturing a polyamic acid composition further comprising the step of cooling the polyamic acid composition to 10 to 30 ℃.
The method of claim 7,
The polymerization reaction is a method for producing a polyamic acid composition performed in a temperature range of 20 to 40°C.
A method of producing a gel film by forming a polyamic acid composition according to any one of claims 1 to 4 and 6 on a support and drying it; And
Method of manufacturing a polyimide film comprising the step of curing the gel film.
The method of claim 12,
The curing is sequentially
The first heat treatment for 5 to 10 minutes at 30 to 50 ℃;
Performing a second heat treatment at 180 to 220° C. for 25 to 35 minutes; And
Method for producing a polyimide film comprising the step of a third heat treatment for 35 to 45 minutes at 440 to 480 ℃.
The method of claim 13,
The first heat treatment to the third heat treatment is a method of manufacturing a polyimide film heated at any one or more heating rates selected from the range of 1 to 10 ℃ / min.
A polyimide film comprising a cured product of the polyamic acid composition of claim 1.
The method of claim 15,
The thermal decomposition temperature (Td) of 1% by weight is 560°C or higher,
The coefficient of thermal expansion is 5 ppm/℃ or less,
Elongation is more than 15%,
Tensile strength is more than 350 MPa,
A polyimide film having a thickness of 10 to 20 μm.
An electronic device comprising the polyimide film according to claim 15 or 16.
The method of claim 17,
The electronic device is an electronic device including a flexible circuit board or a display substrate.