TWI785179B - Method of preparing polyamic acid and polyamic acid, polyimide resin, polyimide film and image display element thereby - Google Patents

Abstract

The present invention relates to a process for preparing a polyamic acid, and a polyamic acid, a polyimide resin, a polyimide film and an image display element prepared thereby, and to a development of polyimide compositions with improved linear thermal expansion coefficients of polyimide films which is prepared by a method of adding one kind of diamine dividedly.

Description

Method for preparing polyamide acid and polyamide acid prepared thereby, Polyimide resin, polyimide film and image display element

The present invention relates to a preparation method of polyamic acid, polyamic acid prepared therefrom, polyimide resin and polyimide film.

Generally, polyimide (PI) film is obtained by filming polyimide resin. Polyimide resin refers to a high heat-resistant resin prepared by combining aromatic dianhydride and aromatic diamine Or after preparing polyamic acid derivatives by solution polymerization of aromatic diisocyanate, the above polyamic acid derivatives are ring-closed and dehydrated at high temperature for imidization.

The above-mentioned polyimide film has excellent mechanical properties, heat resistance, and electrical insulation, so it is widely used in semiconductor insulating films, thin film transistors (Thin Film Transistor, TFT)-Liquid Crystal Display (Liquid Crystal Display) , LCD) electrode protection film, flexible printed wiring circuit substrates and other electronic materials.

However, polyimide resin is brown and yellow due to the high aromatic ring density, so the transmittance in the visible light region is low, and the light transmittance becomes low due to the yellowish color, and it has high birefringence rate, so it is difficult to use as an optical member.

In U.S. Patent Nos. 4,595,548, 4,603,061, 4,645,824, 4,895,972, 5,218,083, 5,093,453, 5,218,077, 5,367,046, 5,338,826, 5,986,036, and 6,232,428 Korean Patent Publication In Publication No. 2003-0009437, it is reported that a monomer having a curved structure in which a meta position other than the para position is connected to a linker such as -O-, -SO ₂ -, CH ₂ -, or a monomer having -CF Aromatic dianhydride monomers and aromatic diamine monomers with ₃ substituents prepare polyimides with a novel structure that improves the transmittance and the transparency of the color tone within the limit of not greatly reducing the thermal properties, but the mechanical properties, heat resistance In terms of properties and birefringence, it is not enough to be used as a material for display elements such as organic light emitting diodes (Organic Light Emitting Diode, OLED), TFT-LCD, and flexible displays.

The present invention provides a method for preparing polyamic acid whose linear thermal expansion coefficient is improved by maintaining the same raw materials and usage amount as the existing composition, changing the input method to maintain optical properties, and polyamic acid and polyimide prepared by this method. An amine resin, a polyimide film, and an image display device including the polyimide film.

A preferred embodiment of the present invention provides a method for preparing polyamic acid, which includes: inputting diamine including bistrifluoromethyl benzidine (2,2'-Bis(trifluoromethyl)benzidine, TFDB) and The step of the dianhydride of pyromellitic dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, PMDA); ) of diamines and include selected from 2,2-bis (3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and one or more dianhydrides of biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA).

The preparation method of the above-mentioned polyamide acid is characterized in that: the molar ratio of the above-mentioned PMDA to one or more selected from 6FDA and BPDA is 90-25:10-75.

The above-mentioned preparation method of polyamide acid is characterized in that: the molar ratio of the above-mentioned PMDA to 6FDA is 90-70:10-30.

The preparation method of the above-mentioned polyamide acid is characterized in that: the molar ratio of the above-mentioned PMDA to BPDA is 90 to 25:10 to 75.

The above-mentioned preparation method of polyamic acid is characterized in that: the molar ratio of the above-mentioned PMDA, 6FDA and BPDA is 90 to 50:5 to 30:5 to 20.

The preparation method of above-mentioned polyamic acid is characterized in that: above-mentioned diamine is more input and is selected from bisaminophenyl fluorene (9,9-Bis (4-aminophenyl) fluorene, FDA) and bisfluoroaminophenyl fluorene (9 , 9-Bis (3-fluoro-4-aminophenyl) fluorene, FFDA) at least one.

The preparation method of above-mentioned polyamic acid is characterized in that: with respect to the total mole of diamine, input with the content of 1 mole% to 20 mole% be selected from above-mentioned bisaminophenyl fluorene (9,9-Bis(4 -aminophenyl)fluorene, FDA) and bisfluoroaminophenyl fluorene (9,9-Bis(3-fluoro-4-aminophenyl)fluorene, FFDA).

Another preferred embodiment of the present invention provides a polyamic acid, which includes: the first block structure, including bistrifluoromethyl benzidine (2,2'-Bis(trifluoromethyl)benzidine, TFDB) The repeating unit derived from pyromellitic dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, PMDA) repeating unit; and the second block structure, including derived from bistrifluoromethylbenzidine (2 ,2'- Bis(trifluoromethyl)benzidine, TFDB) repeating unit derived from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic dianhydride (3,3 ,4,4-Biphenyltetracarboxylic dianhydride, more than one repeating unit in BPDA).

The above polyamide acid is characterized in that the molar ratio of PMDA in the first block structure to one or more selected from 6FDA and BPDA in the second block structure is 90 to 25:10 to 75.

The above polyamide acid is characterized in that the molar ratio of PMDA in the first block structure to 6FDA in the second block structure is 90 to 70:10 to 30.

The above polyamic acid is characterized in that the molar ratio of PMDA in the first block structure to BPDA in the second block structure is 90 to 25:10 to 75.

The above-mentioned polyamic acid is characterized in that: the molar ratio of PMDA in the first block structure, 6FDA in the second block structure, and BPDA in the second block structure is 90 to 50:5 to 30:5 to 20.

The above-mentioned polyamic acid is characterized in that: the second block structure comprising the repeating unit derived from the above-mentioned double TFDB and the repeating unit derived from more than one repeating unit selected from 6FDA and BPDA further comprises a structure derived from the group selected from bisaminophenylfluorene ( More than one repeating unit of 9,9-Bis(4-aminophenyl)fluorene, FDA) and bisfluoroaminophenylfluorene (9,9-Bis(3-fluoro-4-aminophenyl)fluorene, FFDA).

The above-mentioned polyamide acid is characterized in that the content of one or more selected from the above-mentioned FDA and FFDA is 1 mol % to 20 mol % with respect to the total moles of diamines.

Another preferred embodiment of the present invention provides a polyimide resin prepared from the above polyamide acid.

Another preferred embodiment of the present invention provides a kind of polyimide film, and it is made of The above polyimide resin was prepared.

The above-mentioned polyimide film is characterized in that: at 50° C. to 350° C., the coefficient of thermal expansion (Coefficient of Thermal Expansion) is 30 ppm/° C. or less; The degree of yellowness is more than 85%, and the degree of yellowness is less than 10.

Another preferred embodiment of the present invention provides an image display element, which includes a polyimide film.

According to the present invention, it is possible to provide a method for preparing polyamic acid which maintains yellowness and transmittance after forming a thin film or film, and which has an improved coefficient of linear thermal expansion, and polyamic acid and polyimide resin prepared thereby. and polyimide film.

According to an embodiment of the present invention, a method for preparing polyamic acid is provided, which includes: inputting diamine including bis(trifluoromethyl)benzidine (TFDB) and diamine including homo The step of the dianhydride of pyrellitic acid dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, PMDA); Diamines and diamines selected from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA) in one of Step on the dianhydride.

In the present invention, one or more diamines are injected under specific conditions, for example, once and twice, so that the optical properties can be maintained at an excellent level and the linear thermal expansion coefficient can be improved.

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

In the preparation method of the polyamic acid of an embodiment of the present invention, it is preferable to include the following steps to implement: inputting includes bistrifluoromethylbenzidine (2,2'-Bis(trifluoromethyl)benzidine, TFDB) The step of diamine and the dianhydride comprising pyromellitic dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, PMDA); (trifluoromethyl)benzidine, TFDB) and diamines selected from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic dianhydride (3,3, 4,4-Biphenyltetracarboxylic dianhydride, BPDA) in the step of more than one dianhydride.

Preferably, the molar ratio of the aforementioned PMDA to one or more selected from 6FDA and BPDA is 90 to 25:10 to 75, preferably 90 to 30:10 to 70.

When the above-mentioned PMDA and one or more selected from 6FDA and BPDA deviate from the above-mentioned molar ratio range, there will be a problem of having a yellowness of 10 or more or having a thermal expansion coefficient of 30 ppm/° C. or more.

In this specification, diamines including the above-mentioned bis(trifluoromethyl)benzidine (TFDB) and pyromellitic dianhydride (1,2,4,5 -benzene tetracarboxylic dianhydride, PMDA) of the dianhydride step named as 1 input, the input includes two trifluoromethyl benzidine (2,2 '-Bis (trifluoromethyl) benzidine, TFDB) diamine and include selected from 2 ,2-double (3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA) in the step of naming more than one dianhydride It is two inputs, but this situation is only named to distinguish the input steps, not to limit the input sequence.

At this time, when adding one or more to two or more selected from 6FDA and BPDA during the above-mentioned 2-time input, it means that the amount of dianhydride injected during the 2-time input is relative to the PMDA when the 1-time input is mentioned above. Total mole.

In addition, in the case of selecting 6FDA from one or more of 6FDA and BPDA during the above-mentioned 2-time input, it is preferable that the mol ratio of the PMDA when the above-mentioned 1-time input and 2-time input is 6FDA is 90 to 70: 10 to 30, preferably 90 to 75: 10 to 25.

When the PMDA during the above-mentioned 1-time input and the 6FDA during the 2-time input deviate from the above-mentioned molar ratio range, if the ratio of PMDA becomes higher than the above-mentioned range, there will be a linear thermal expansion coefficient that becomes very low, but the yellowness The problem of becoming very high, if the ratio of 6FDA is higher than the above range, there is an advantage that the degree of yellowness becomes very low, but there is a problem that the coefficient of linear thermal expansion increases.

In addition, in the case of selecting BPDA from one or more of 6FDA and BPDA during the above-mentioned 2-time input, it is preferable that the mol ratio of PMDA when the above-mentioned 1-time input and BPDA when 2-time input is 90 to 25: 10 to 75, preferably 85 to 30: 15 to 70.

When the PMDA when the above-mentioned 1-time input and the BPDA when the 2-time input deviate from the above-mentioned molar ratio range, if the ratio of PMDA becomes higher than the above-mentioned range, there will be a linear thermal expansion coefficient that becomes very low, but the yellowness Becomes very high problem, if the ratio of BPDA becomes higher than the above range, it has yellowness lower than PMDA Advantages, but there will be a problem of increased linear thermal expansion coefficient.

In one embodiment of the present invention, when throwing in above-mentioned 2 times when throwing in the situation that is selected from more than one kind in 6FDA and BPDA more than two kinds, PMDA when above-mentioned 1 throwing, 6FDA and 2 when throwing 2 times The molar ratio of BPDA in the second input is more preferably 90 to 50:5 to 30:5 to 20.

When the PMDA at the time of the first injection and the 6FDA and BPDA at the time of the second injection are out of the above-mentioned molar ratio range, there will be a problem of having a yellowness of 10 or more or having a thermal expansion coefficient of 30 ppm/° C. or more.

In the present invention, in terms of improving the coefficient of linear thermal expansion and the yellowness at the same time, the situation of adding more than one dianhydride selected from 6FDA and BPDA after first adding the dianhydride comprising the above-mentioned PMDA is later. The situation is even better with the dianhydride of PMDA.

That is, in one embodiment of the present invention, in terms of the aspect that can further improve the properties of the present invention, it is preferable to firstly input the compound containing bis(trifluoromethyl)benzidine (2,2'-Bis(trifluoromethyl)benzidine, TFDB ) of diamine and dianhydride including pyromellitic dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, PMDA), and then input including bistrifluoromethyl benzidine (2,2'-Bis(trifluoromethyl ) benzidine, TFDB) and diamines selected from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic dianhydride (3,3,4, 4-Biphenyltetracarboxylic dianhydride, BPDA) in more than one dianhydride.

In addition, the diamine in the above-mentioned 2 times input can be further input selected from bisaminophenyl fluorene (9,9-Bis(4-aminophenyl)fluorene, FDA) and bisfluoroaminophenyl fluorene (9,9-Bis (3-fluoro-4-aminophenyl)fluorene, FFDA) more than one. Yu Geng When one or more kinds selected from the above-mentioned FDA and FFDA are added, the effect of improving the glass transition temperature can be obtained.

Preferably, one or more selected from the aforementioned FDA and FFDA is contained in a content of 1 to 20 mol%, preferably 1 to 10 mol%, relative to the total moles of diamines. When one or more selected from the above-mentioned FDA and FFDA deviates from the above-mentioned range, if it is less than 1 mol%, the content is too small to have almost no effect of improving the glass transition temperature, and if it exceeds 20 mol%, it will be There is a problem that the yellowness and the thermal expansion coefficient are lowered.

According to an embodiment of the present invention, it may include the following steps to implement: after the above-mentioned 2 inputs, 3 inputs including bis(trifluoromethyl)benzidine (2,2'-Bis(trifluoromethyl)benzidine, TFDB) Amines and compounds selected from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA) One or more dianhydrides in

The diamine and dianhydride at the time of the said 3 times of charging can be adjusted suitably within the molar ratio range of the said 1 time of charging and the dianhydride of the 2 times of charging, and can add it.

As a diamine used in an embodiment of the present invention, in addition to TFDB, FDA and FFDA, it may include diamines selected from oxydianiline (4,4'-Oxydianiline, ODA), p-phenylenediamine (para-phenylene diamine, pPDA), meta-phenylene diamine (mPDA), para-Methylene Dianiline (pMDA), meta-Methylene Dianiline (mMDA), diaminobenzene Oxybenzene (1,3-Bis(3-aminophenoxy)benzene, 133APB), bisaminophenoxybenzene (1,3-Bis(4-aminophenoxy)benzene, 134APB), bisaminophenoxyphenyl Hexafluoropropane (2,2'-bis[4(4- aminophenoxy)phenyl]hexafluoropropane, 4BDAF), bisaminophenyl hexafluoropropane (2,2'-Bis(3-aminophenyl)hexafluoropropane, 33-6F), bisaminophenyl hexafluoropropane (2,2'- Bis(4-aminophenyl)hexafluoropropane, 44-6F), Bis(4-aminophenyl)sulfone, 4DDS), Bis(3-aminophenyl)sulfone, 3DDS), ring Hexanediamine (1,3-Cyclohexanediamine, 13CHD), Cyclohexanediamine (1,4-Cyclohexanediamine, 14CHD), Diaminophenoxyphenylpropane (2,2-Bis[4-(4- aminophenoxy)-phenyl]propane, 6HMDA), bisaminohydroxyphenyl hexafluoropropane (2,2-Bis(3-amino-4-hydroxy-phenyl)-hexafluoropropane, 6FAP), bisaminophenoxydiphenyl One or more kinds of bases (4,4'-Bis(3-aminophenoxy)diphenyl sulfone, DBSDA) are not limited to the kinds mentioned here.

On the other hand, in addition to PMDA, 6FDA, and BPDA, the dianhydride used in the present invention may include 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene -1,2-dicarboxylic anhydride (TDA), benzophenone tetracarboxylic dianhydride (3,3,4,4-Benzophenone tetracarboxylic dianhydride, BTDA), oxygen bisphthalic dianhydride (4,4- Oxydiphthalic dianhydride, ODPA), bis(3,4-dicarboxyphenyl) dimethyl-silane dianhydride (SiDA), bis-dicarboxyphenoxydiphenyl sulfide dianhydride (4,4- Bis(3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, BDSDA), Sulfonyldiphthalic anhydride (SO ₂ DPA), cyclobutane tetracarboxylic dianhydride (Cyclobutane-1,2,3, More than one of 4-tetracarboxylic dianhydride, CBDA), isopropylidene diphenoxy diphthalic anhydride (4,4'-(4,4'-Isopropylidenediphenoxy) Bis(phthalic anhydride), 6HBDA), and not Restricted to the species mentioned here.

In one embodiment of the present invention, the above-mentioned diamine and dianhydride components are included to participate in the polymerization reaction.

The conditions for the above reaction are not particularly limited, but the reaction temperature is preferably 0° C. to 80° C., and the reaction time is preferably 2 hours to 48 hours. In addition, when carrying out the reaction, an inert gas atmosphere such as argon or nitrogen is more preferable.

The organic solvent used for the solution polymerization reaction of the above-mentioned monomers is not particularly limited as long as it dissolves polyamic acid. As a known reaction solvent, a solvent selected from m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl Azolein (DMSO), acetone, ethyl acetate, diethylformamide (DEF), diethylacetamide (DEA), propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether ethyl Propylene glycol monomethyl ether Acetate (PGMEA), ethyl lactate (Ethyl Lactate), 3-methoxy-N,N-dimethylpropionamide (3-Methoxy-N,N-Dimethylpropionamide), 3- One or more polar solvents in 3-Butoxy-N,N-methylpropionamide. Besides, low-boiling point solutions such as tetrahydrofuran (THF), chloroform, or low-absorption solvents such as γ-butyrolactone may also be used. Such solvents may be used alone or in two or more kinds according to purposes, and are not limited to the kinds mentioned here.

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

According to another embodiment of the present invention, a polyamic acid is provided, which includes: the first block structure, including bistrifluoromethyl benzidine (2,2'-Bis(trifluoromethyl)benzidine, TFDB) repeat unit derived from pyromene Formic acid dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, PMDA) repeating unit; and the second block structure, including bis trifluoromethyl benzidine , TFDB) with repeating units derived from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic dianhydride (3,3,4,4- Biphenyltetracarboxylic dianhydride, more than one repeating unit in BPDA).

The above-mentioned polyamic acid is preferably prepared by the above-mentioned preparation method.

The polyamic acid prepared by the above preparation method is fed into a diamine in batches to include a first block structure and a second block structure including a diamine in a specific content, thereby obtaining the following effects: yellowness and transmittance The degree is not lower than that of the polyamic acid prepared by a one-time input method as in the existing method, and the linear thermal expansion coefficient is improved.

Preferably, the molar ratio of PMDA in the first block structure to one or more selected from 6FDA and BPDA in the second block structure is 90 to 25:10 to 75, preferably 90 to 30:10 to 70.

When PMDA in the above-mentioned first block structure and one or more selected from 6FDA and BPDA in the second block structure deviate from the above-mentioned molar ratio range, there will be a yellowness of 10 or more or 30ppm/°C The above coefficient of thermal expansion problem.

In addition, the molar ratio of PMDA in the first block structure to 6FDA in the second block structure is preferably 90 to 70:10 to 30, preferably 90 to 75:10 to 25.

When the PMDA in the above-mentioned first block structure and the 6FDA in the second block structure deviate from the above-mentioned molar ratio range, if the ratio of PMDA becomes higher than the above-mentioned range, there will be a linear thermal expansion coefficient that becomes very low , but the yellowness becomes non- If the ratio of 6FDA is higher than the above-mentioned range, there is an advantage that the yellowness becomes very low, but there is a problem that the coefficient of linear thermal expansion increases.

In addition, the molar ratio of PMDA in the first block structure to BPDA in the second block structure is preferably 90 to 25:10 to 75, preferably 85 to 30:15 to 70.

When the PMDA in the above-mentioned 1st block structure and the BPDA in the 2nd block structure deviate from the above-mentioned molar ratio range, if the ratio of PMDA becomes higher than the above-mentioned range, there will be a linear thermal expansion coefficient that becomes very low , but the yellowness becomes very high. If the ratio of BPDA becomes higher than the above range, there is an advantage that the yellowness is lower than PMDA, but there is a problem that the linear thermal expansion coefficient increases.

In one embodiment of the present invention, it is more preferable that the molar ratio of PMDA in the first block structure, 6FDA in the second block structure and BPDA in the second block structure is 90 to 50:5 to 30:5 to 20, preferably 90 to 55:5 to 30:5 to 15.

When PMDA in the above-mentioned first block structure, 6FDA and BPDA in the second block structure deviate from the above-mentioned molar ratio range, there will be a problem of having a yellowness of 10 or more or having a thermal expansion coefficient of 30 ppm/°C or more .

In addition, the second block structure including repeating units derived from the above-mentioned bisTFDB and repeating units derived from one or more types of repeating units selected from 6FDA and BPDA may further include More than one repeating unit of 4-aminophenyl)fluorene, FDA) and 9,9-Bis(3-fluoro-4-aminophenyl)fluorene, FFDA). When one or more selected from the above-mentioned FDA and FFDA is further included, the effect of improving the glass transition temperature can be obtained.

Preferably, one or more selected from the aforementioned FDA and FFDA is contained in a content of 1 to 20 mol%, preferably 1 to 10 mol%, relative to the total moles of diamines. When one or more selected from the above-mentioned FDA and FFDA deviates from the above-mentioned range, if it is less than 1 mol%, the content is too small to have almost no effect of improving the glass transition temperature, and if it exceeds 20 mol%, it will be There is a problem that the yellowness and the thermal expansion coefficient are lowered.

The method for preparing the polyimide resin by imidizing the above-mentioned polyamide acid is not particularly limited, and a conventionally known method can be used. As a method for imidizing the above-mentioned polyamide acid, thermal imidization method, chemical imidization method, or a combination of thermal imidization method and chemical imidization method can be applied, and it is more preferable to use Thermal imidization method. More preferably, the solution subjected to the chemical imidization method is purified, dried, and then dissolved in a solvent again for use after precipitation. The solvent is the same as the solvent mentioned above. The chemical imidization method is to apply a dehydrating agent represented by acid anhydrides such as acetic anhydride and an imidized catalyst represented by tertiary amines such as isoquinoline, β-picoline, and pyridine to polyamide Amino acid solution method. The thermal imidization method can be used in combination with the chemical imidization method, and the heating conditions can be changed according to the type of polyamic acid solution, film thickness, etc.

According to another embodiment of the present invention, a polyimide film prepared from the above polyimide resin is provided.

It is also possible to, after imidizing the obtained polyamic acid solution, put the imidized solution into a second solvent for precipitation, filtration and drying to obtain the solid content of the polyimide resin. The obtained polyimide resin solid content is dissolved in the polyimide solution obtained by the 1st solvent, and the above-mentioned polyimide film is obtained by a film-forming process.

That is, when the above-mentioned polyamic acid is prepared by chemical imidization Afterwards, the amine resin is precipitated, dried, dissolved in a solvent, solubilized, and applied to a support, and the applied solution is formed into a film on the support by drying air and heat treatment.

The above-mentioned first solvent can use the same solvent as the solvent used when polymerizing the polyamic acid solution, and the above-mentioned second solvent can use a polarity lower than that of the first solvent in order to obtain the solid content of the polyamic acid resin. Specifically, It may be one or more selected from water, alcohols, ethers, and ketones. At this time, the content of the second solvent is not particularly limited, but is preferably 5 times by weight to 20 times by weight relative to the weight of the polyamic acid solution.

The filming temperature of the above-mentioned solution to be applied is preferably 250°C to 500°C, and glass plates, aluminum foils, circulating stainless steel belts, stainless steel drums, etc. can be used as supports.

The processing time required for film formation varies depending on the temperature, the type of support, the amount of polyamic acid solution to be applied, and the mixing conditions of the catalyst, and is not limited to a fixed time. It is preferably performed within the range of 5 minutes to 30 minutes.

The heat treatment is performed at a temperature between 100° C. and 500° C., and the treatment time is between 1 minute and 30 minutes. After performing heat treatment to complete drying and imidization, it is peeled off from the support.

The thickness of the obtained polyimide film is not particularly limited, but is preferably in the range of 10 μm to 250 μm, more preferably 10 μm to 100 μm.

In addition, the term "polyimide" in the present invention may include polyimide-based polymers such as polyimide-amide.

The polyimide film prepared in the present invention preferably has a coefficient of thermal expansion (Coefficient of Thermal Expansion) at 50° C. to 350° C. of 30 ppm/° C. or less.

The polyimide film prepared in the present invention is preferably based on the thickness of 10 μm to 100 μm and when the transmittance is measured with a UV spectrometer, the transmittance at 550 nm It is more than 85%, preferably more than 90%.

In addition, the polyimide film preferably has a yellowness of 10 or less, preferably 5 or less, based on a film thickness of 10 μm to 100 μm.

Hereinafter, the present invention will be described in more detail with reference to examples, but the scope of the present invention is not limited to the following examples.

<Example 1>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 273.882g of N-methyl-2-pyrrolidone (NMP ) after, dissolve the TFDB of 28.821g, then stir for 3 hours after dropping into the PMDA of 19.631g. Thereafter, after 3.202 g of TFDB was further dissolved, 4.443 g of 6FDA was added and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 370° C., it was subjected to isothermal treatment for 30 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Example 2>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 284.922g of N-methyl-2-pyrrolidone (NMP ) after, dissolve the TFDB of 25.618g, then stir for 3 hours after dropping into the PMDA of 17.450g. Thereafter, after dissolving 6.405 g of TFDB more, 8.885 g of 6FDA was added and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80°C for 20 minutes. After reaching 370°C, it was subjected to isothermal treatment for 30 minutes. hardening. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Example 3>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 295.963g of N-methyl-2-pyrrolidone (NMP ) after, dissolve the TFDB of 22.416g, then stir for 3 hours after dropping into the PMDA of 15.268g. Thereafter, after dissolving 9.607 g of TFDB more, 13.328 g of 6FDA was added and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 370° C., it was subjected to isothermal treatment for 30 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Example 4>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 295.963g of N-methyl-2-pyrrolidone (NMP ), after dissolving 9.607g of TFDB, and then stirring for 3 hours after dropping into 13.328g of 6FDA. Thereafter, after dissolving 22.416 g of TFDB more, PMDA 15.268 g was added and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 370° C., it was subjected to isothermal treatment for 30 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Example 5>

For passing nitrogen gas through a reactor attached with a stirrer, nitrogen injection device 500ml reactor with a dropping funnel, a temperature regulator and a cooler, and after filling 281.419g of N-methyl-2-pyrrolidone (NMP), dissolve 16.012g of TFDB, and then drop into 10.906g of Stir after PMDA for 3 hours. Thereafter, after dissolving 16.012 g of TFDB more, 14.711 g of BPDA was added and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 350° C., it was subjected to isothermal treatment for 10 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Example 6>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 283.076g of N,N-dimethylacetamide (DMAc ) after, dissolve the TFDB of 13.450g, then stir 3 hours after dropping into the PMDA of 9.161g. Thereafter, after dissolving 23.825 g of TFDB and 1.384 g of FFDA, 22.949 g of BPDA was added and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 20% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 350° C., it was subjected to isothermal treatment for 10 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Example 7>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 288.638g of N-methyl-2-pyrrolidone (NMP ), dissolve 22.416g of TFDB, after that, stirred for 3 hours after throwing in 15.268 g of PMDA. Thereafter, after dissolving 9.607 g of TFDB more, 8.885 g of 6FDA was added and reacted for 3 hours. Finally, 2.942 g of BPDA was added and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 370° C., it was subjected to isothermal treatment for 30 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Embodiment 8>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 288.638g of N-methyl-2-pyrrolidone (NMP ) after, dissolve the TFDB of 22.416g, then stir for 3 hours after dropping into the PMDA of 15.268g. Thereafter, after dissolving 6.405 g of TFDB more, 8.885 g of 6FDA was added and reacted for 3 hours. Finally, after dissolving 3.202 g of TFDB, 2.942 g of BPDA was added and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 370° C., it was subjected to isothermal treatment for 30 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative example 1>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 268.362g of N-methyl-2-pyrrolidone (NMP ) after, dissolve the TFDB of 32.023g, then stir for 3 hours after dropping into the PMDA of 20.721g. Thereafter, put 2.221g of 6FDA was reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 370° C., it was subjected to isothermal treatment for 30 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative example 2>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 295.963g of N-methyl-2-pyrrolidone (NMP ) after, dissolve the TFDB of 32.023g, then stir for 3 hours after dropping into the PMDA of 15.268g. Thereafter, 13.328 g of 6FDA was added and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 370° C., it was subjected to isothermal treatment for 30 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative example 3>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and 295.963g of N-methyl-2-pyrrolidone (NMP ), after dissolving 32.023g of TFDB, and then stirring for 3 hours after dropping into 13.328g of 6FDA. Thereafter, 15.268 g of PMDA was put and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 370° C., it was subjected to isothermal treatment for 30 minutes to harden. Thereafter, cool down slowly A polyimide film was obtained by separating from a glass plate.

<Comparative example 4>

Nitrogen was passed through a 500ml reactor attached with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator and a cooler as a reactor, and filled with 301.483g of N-methyl-2-pyrrolidone (NMP ) After, dissolve the TFDB of 32.023g, then stir 3 hours after dropping into the PMDA of 14.178g. Thereafter, 15.549 g of 6FDA was put and reacted for 15 hours. As a result, a polyamic acid solution having a solid content concentration of 17% by weight was obtained. After the reaction was completed, the obtained solution was applied to a glass plate, and then treated with hot air at 80° C. for 20 minutes. After reaching 370° C., it was subjected to isothermal treatment for 30 minutes to harden. Thereafter, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

The properties of the polyimide films prepared in the above-mentioned Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Table 1 below.

(1) Transmittance (TT) measurement

The transmittance at 550 nm was measured three times with a UV spectrometer (Konita Minolta, CM-3700d), and the average value is described in Table 1.

(2) Determination of yellowness (Y.I.)

The degree of yellowness was measured using a UV spectrometer (Konita Minolta, CM-3700d) according to the American Society for Testing Materials (ASTM) E313 standard.

(3) Measurement of coefficient of thermal expansion (CTE)

Using a thermomechanical analyzer (Thermomechanical Analyzer, TMA) (TA Instrument Company, Q400) according to the thermomechanical analysis (Thermomechanical Analysis, TMA) - method (Method) for linear thermal expansion at 50 ℃ to 350 ℃ The expansion coefficient was measured twice. The size of the test piece was set to 4mm×24mm, the load was set to 0.02N, and the heating rate was set to 10°C/min. During film formation, residual stress will remain in the film due to heat treatment. Therefore, after the residual stress is completely removed by the first operation (Run), the second value is expressed as the actual measured value.

As shown in the above table 1, the examples and the comparative examples are compared respectively, and the yellowness, transmittance and linear thermal expansion coefficient of the examples 1 to 8 that are put into TFDB in batches are all excellent levels, but the comparative example 1 The transmittance decreased significantly, and Comparative Examples 2 to 4 exhibited a property in which the coefficient of linear thermal expansion decreased significantly.

From this, it can be known that the trade-off relationship between the yellowness and the linear thermal expansion coefficient can be overcome by injecting TFDB in batches in Examples 1 to 8.

In addition, when PMDA is used as the primary dianhydride and 6FDA is used as the secondary dianhydride In the case of anhydride, the content of PMDA is preferably more than 65 mol% in order to have a linear thermal expansion coefficient of 30ppm/°C or less, and the content of PMDA is preferably not more than 90 mol% in order to prevent the yellowness from decreasing. In addition, even if BPDA is used as the secondary dianhydride, the same effect can be obtained. Even if FFDA is used more, the linear thermal expansion coefficient can be improved by adding TFDB in batches. Observing Example 3 and Example 4, it can be seen that the improvement effect when the primary dianhydride is PMDA is greater than that of 6FDA. Furthermore, observing Example 7 and Example 8, it can be confirmed that when tertiary dianhydride is applied, the more TFDB is charged in batches, the more the coefficient of linear thermal expansion is improved.

Claims (18)

A preparation method of polyamic acid, which comprises: the step of inputting diamine comprising bistrifluoromethylbenzidine and dianhydride comprising pyromellitic dianhydride; and inputting diamine comprising bistrifluoromethylbenzidine; A step of amine and one or more dianhydrides selected from the group consisting of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and biphenyltetracarboxylic dianhydride. The preparation method of polyamic acid as described in item 1 of the patent scope of the application, wherein the pyromellitic dianhydride and the selected from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride The molar ratio of one or more of biphenyltetracarboxylic dianhydrides is 90 to 25:10 to 75. The preparation method of polyamic acid as described in item 1 of the scope of patent application, wherein the molybdenum of pyromellitic dianhydride and 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride The ear ratio is 90 to 70:10 to 30. The preparation method of polyamic acid as described in item 1 of the scope of the patent application, wherein the molar ratio of pyromellitic dianhydride to biphenyltetracarboxylic dianhydride is 90 to 25:10 to 75. The preparation method of polyamic acid as described in item 1 of the patent scope of the application, wherein the pyromellitic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and bis- The molar ratio of benzene tetracarboxylic dianhydride is 90 to 50:5 to 30:5 to 20. The preparation method of polyamic acid as described in item 1 of the scope of the patent application, wherein the diamine is further added with one or more selected from bisaminophenylfluorene and bisfluoroaminophenylfluorene. The preparation method of polyamic acid as described in item 6 of the patent scope of the application, wherein relative to the total mole of diamine, the content of 1 mole% to 20 mole% is added to the selected One or more of the above-mentioned bisaminophenylfluorene and bisfluoroaminophenylfluorene. A polyamic acid, which is prepared by the preparation method of polyamic acid described in any one of the first to seventh items of the scope of patent application, which includes: the first block structure, including the A repeating unit of fluoromethylbenzidine and a repeating unit derived from pyromellitic dianhydride; and a second block structure comprising a repeating unit derived from bistrifluoromethylbenzidine and a repeating unit derived from One or more repeating units of (3,4-dicarboxyphenyl)hexafluoropropane dianhydride and biphenyltetracarboxylic dianhydride. The polyamic acid as described in item 8 of the patent scope of the application, wherein the pyromellitic dianhydride in the first block structure and the pyromellitic dianhydride in the second block structure are selected from 2,2-bis(3,4 - The molar ratio of one or more of dicarboxyphenyl) hexafluoropropane dianhydride and biphenyltetracarboxylic dianhydride is 90 to 25:10 to 75. The polyamic acid as described in item 8 of the scope of patent application, wherein the pyromellitic dianhydride in the first block structure and the 2,2-bis(3,4-bis) in the second block structure The molar ratio of carboxyphenyl)hexafluoropropane dianhydride is 90 to 70:10 to 30. The polyamic acid as described in item 8 of the scope of application for patents, wherein the molar ratio of pyromellitic dianhydride in the first block structure to biphenyltetracarboxylic dianhydride in the second block structure For 90 to 25: 10 to 75. The polyamic acid as described in item 8 of the scope of patent application, wherein the pyromellitic dianhydride in the first block structure, the 2,2-bis(3,4-di The molar ratio of carboxyphenyl)hexafluoropropane dianhydride to biphenyltetracarboxylic dianhydride in the second block structure is 90 to 50:5 to 30:5 to 20. The polyamic acid as described in item 8 of the patent scope of the application, which includes repeating units derived from bistrifluoromethylbenzidine and derived from 2,2-bis(3,4-dicarboxylic The second block structure of more than one repeating unit in hexafluoropropane dianhydride and biphenyltetracarboxylic dianhydride further includes More than one repeating unit in fluorene. The polyamic acid as described in item 13 of the scope of the patent application, wherein the content of one or more selected from the bisaminophenylfluorene and bisfluoroaminophenylfluorene is 1 with respect to the total mole of the diamine Mole % to 20 Mole %. A kind of polyimide resin, it is prepared by polyamide acid as described in item 8 of the scope of application. A polyimide film, which is prepared from the polyimide resin described in item 15 of the scope of the patent application. For the polyimide film described in item 16 of the patent application, its thermal expansion coefficient at 50°C to 350°C is below 30ppm/°C, and its transmittance at 550nm is above 85% when measured by an ultraviolet spectrometer, The degree of yellowness is 10 or less. An image display element, which includes the polyimide film described in item 16 of the patent application.