JP6929355B2 - Polyamic acid, polyimide, polyimide film, image display device containing this, and method for producing polyamic acid - Google Patents

Description

The present invention relates to polyamic acids, polyimides, polyimide films having a low linear thermal expansion coefficient of 10 ppm / ° C. or less and a glass transition temperature of 350 ° C. or higher and improved yellowness, image display elements containing these, and polyamic acids. Regarding the manufacturing method.

Generally, a polyimide (PI) film is a film made of a polyimide resin, and the polyimide resin is obtained by solution-polymerizing an aromatic dianhydride with an aromatic diamine or an aromatic diisocyanate to produce a polyamic acid derivative. A highly heat-resistant resin produced by ring-closure dehydration at high temperature and imidization.
Since such a polyimide film has excellent mechanical properties, heat resistance, and electrical insulation, it is widely used in electronic materials such as semiconductor insulating films, TFT-LCD electrode protective films, and flexible printed wiring circuit substrates. in use.
However, the polyimide resin is colored brown and yellow due to the high density of aromatic rings, has low transmittance in the visible light region, exhibits a yellowish color, has low light transmittance, and has a large double refractive index. It is difficult to use as an optical member.
US Pat. , the same No. 6232428 Patent and Korean Patent Publication No. 2003-0009437 _{is, -O -, - SO 2 -} , CH 2 - linking group, such as, rather than the p-position, of the linked bent structure m-position A polyimide with a novel structure in which the transparency and the transparency of the hue are improved within the limit that the thermal properties are not significantly deteriorated by using an aromatic dianhydride having a substituent such as a monomer or -CF _{3 and an aromatic diamine monomer.} There is a report that it was manufactured. However, in terms of mechanical properties, heat resistance, and birefringence, it is still insufficient to be used as a material for display elements such as OLEDs, TFT-LCDs, and flexible displays.

The polyimide produced in the present invention introduces a diamine having a benzidine structure in order to improve the yellowness while maintaining the heat resistance of the colored PI in the same manner, and further contains an appropriate proportion of the monomers contained in the diamine and the dianhydride. Polyamic acid, polyimide, polyimide film, image display element containing this, and polyamic acid having a low linear thermal expansion coefficient of 10 ppm / ° C or less and a glass transition temperature of 350 ° C or more and improved yellowness. It is an object of the present invention to provide a manufacturing method.

In order to achieve the above object, a preferred embodiment of the present invention is a polyamic acid containing a repeating unit derived from diamine and a repeating unit derived from dianhydride, wherein the repeating unit derived from diamine is bistrifluoro. The repeating unit derived from m-phenylenediamine includes a repeating unit derived from methylbenzidine and a repeating unit derived from m-phenylenediamine, and the repeating unit derived from the diamine is 10 to 20 mol% with respect to 100 mol% of the repeating unit derived from the diamine. The repeating unit derived from the dianhydride includes a repeating unit derived from pyromellitic acid dianhydride and a repeating unit derived from biphenyltetracarboxylic acid dianhydride, and the repeating unit derived from the biphenyltetracarboxylic acid. The repeating unit derived from acid dianhydride is a polyamic acid contained in a molar ratio of 1: 1 to 1.5 with respect to the repeating unit derived from m-phenylrangeamine.
The repeating unit derived from the diamine further contains 1 to 10 mol% of the repeating unit derived from bisfluoroaminophenylfluorene with respect to 100 mol% of the repeating unit derived from the diamine.
The repeating unit derived from the diamine contains the repeating unit derived from the m-phenylenediamine and the repeating unit derived from the bisfluoroaminophenylfluorene in a total amount of more than 10 mol% and not more than 20 mol%.
Another preferred embodiment of the present invention is a polyimide containing a repeating unit derived from a diamine and a repeating unit derived from a dianhydride, wherein the repeating unit derived from the diamine is a repeating unit derived from bistrifluoromethylbenzidine. And the repeating unit derived from m-phenylenediamine, and the repeating unit derived from m-phenylenediamine is contained in a content of 10 to 20 mol% with respect to 100 mol% of the repeating unit derived from the diamine. The repeating unit derived from the dianhydride includes a repeating unit derived from pyromellitic acid dianhydride and a repeating unit derived from biphenyltetracarboxylic acid dianhydride, and the repeating unit derived from the biphenyltetracarboxylic acid dianhydride. The unit is a polyimide contained in a molar ratio of 1: 1 to 1.5 with respect to the repeating unit derived from the m-phenylenediamine.
The repeating unit derived from the diamine further contains 1 to 10 mol% of the repeating unit derived from bisfluoroaminophenylfluorene with respect to 100 mol% of the repeating unit derived from the diamine.
The repeating unit derived from the diamine contains the repeating unit derived from the m-phenylenediamine and the repeating unit derived from the bisfluoroaminophenylfluorene in a total amount of more than 10 mol% and not more than 20 mol%.
Another preferred embodiment of the present invention is a polyimide film containing the above-mentioned polyimide.
Another preferred embodiment of the present invention is an image display device containing the polyimide film described above.

Another preferred embodiment of the present invention is a step (S1) of adding a diamine containing bistrifluoromethylbenzidine and m-phenylenediamine to a solvent and dissolving the diamine to produce a diamine solution, and the step (S1). This is a method for producing a polyamic acid, which comprises a step (S2) of adding a dianhydride containing a biphenyltetracarboxylic dianhydride and a pyromellitic dianhydride to a diamine solution and reacting the diamine solution.
In the S1 step, the m-phenylenediamine is added in an amount of 10 to 20 mol% with respect to 100 mol% of the diamine.
When the diamine solution is produced in the S1 step, bisfluoroaminophenylfluorene is added in a content of 1 to 10 mol% with respect to 100 mol% of the diamine.
When the diamine solution is produced in the S1 step, the m-phenylenediamine and the bisfluoroaminophenylfluorene are added in a total amount of more than 10 mol% and not more than 20 mol%.
In the S2 step, the biphenyltetracarboxylic dianhydride is added in a molar ratio of 1: 1 to 1.5 with respect to the repeating unit derived from the m-phenylenediamine.
In the S2 step, biphenyltetracarboxylic dianhydride is added to the diamine solution produced in the S1 step for a primary reaction, and then pyromellitic dianhydride is added for a secondary reaction.
The primary reaction in the S2 step is carried out at 25 to 30 ° C. for 3 to 5 hours.
The secondary reaction in the S2 step is carried out at 25 to 40 ° C. for 12 to 20 hours.

According to the present invention, it is possible to provide a polyimide film having heat resistance similar to that of a colored PI and having improved yellowness and transmittance after the film and the film are formed.

According to one embodiment of the present invention, in a polyamic acid containing a repeating unit derived from a diamine and a repeating unit derived from a dianhydride, the repeating unit derived from the diamine is bistrifluoromethylbenzidine (2,2'-. It contains a repeating unit derived from bis (trifluoromethyl) benzidine, TFDB) and a repeating unit derived from m-phenylenediamine (mPDA), and is derived from the above-mentioned m-phenylenediamine (mPDA). The repeating unit is contained in a content of 10 to 20 mol% with respect to 100 mol% of the repeating unit derived from the diamine, and the repeating unit derived from the dianhydride is pyromellitic acid dianhydride (1, 2). , 4,5-benzene terracarboxylic diamine, pyromethylticicid diamine, PMDA) and biphenyltetracarboxylic acid dianhydride (3,3,4,5-biphenyltetracarboxydiamine) The repeating unit derived from biphenyltetracarboxylic acid dianhydride (3,3,4,4-Biphenyltetracarboxylic diamine, BPDA) is a molar of 1: 1 to 1.5 with respect to the repeating unit derived from the m-phenylenediamine. The polyamic acid contained in the ratio can be provided.
The "derived repeating unit" described in the present invention means that the structure of the monomer repeatedly appears in the polymer while the monomers for forming the polymer are linked between the monomers. This is a term widely used in the field to which the present invention belongs. As an example, polyethylene is a polymer having a repeating unit derived from ethylene, and the structure of the ethylene monomer is a polyethylene polymer while the ethylene monomers are linked to each other. It means that it appears repeatedly in.

The polyamic acid according to the present invention has, as a repeating unit derived from a diamine, a repeating unit derived from bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and m-phenylenediamine, m-phenylenediamine, The repeating units derived from mPDA), and the repeating units derived from dianhydride, are the repeating units derived from pyromellitic dianhydride (1,2,4,5-benzene terracarboxylic diamine, pyromelliticacid diamine, PMDA) and Includes repeating units derived from biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA).

As the diamine, other diamines other than bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and m-phenylenediamine (meta-phenylene diamine, mPDA) can be contained, and as an example, oxy Dianiline (4,4'-Oxydianiline, ODA), p-phenylenediamine (para-phenylene diamine, pPDA), p-methylene dianiline (para-Methylene Dianline, pMDA), m-methylenedialine , MMDA), bisaminophenoxybenzene (1,3-bis (3-aminophenoxy) aminee, 133APB), bisaminophenoxybenzene (1,3-bis (4-aminophenoxy) aminee, 134APB), bisaminophenoxyphenylhexafluoro Propane (2,2'-bis [4 (4-aminophenoxy) amineyl] hexafluoropropane, 4BDAF), bisaminophenyl hexafluoropropane (2,2'-bis (3-aminophenoy) hexafluoropropane, 33-6F), bisaminophenyl Hexafluoropropane (2,2'-bis (4-aminophenyl) hexafluoropropane, 44-6F), bisaminophenyl sulfone (bis (4-aminophenyl) sulfone, 4DDS), bisaminophenyl sulfone (bis (3-aminophenyl) sulfone , 3DDS), cyclohexanediamine (1,3-Cyclohexanediamine, 13CHD), cyclohexanediamine (1,4-Cyclohexanediamine, 14CHD), bisaminophenoxyphenylpropane (2,2-Biz [4- (4-aminophenoxy) -phenyl] Propane, 6HMDA), bisaminohydroxyphenylhexafluoropropane (2,2-Biz (3-amino-4-hydroxy-phenyl) -hexafluoropropane, DBOH), bisaminophenoxydiphenylsulfone (4,4'-Biz (3-4'-Biz)) amineo phenoxy) d iphenylsulfone, DBSDA), bisaminophenylfluorene (9,9-Bis (4-aminophenyl) fluoride, FDA), bisfluoroaminophenylfluorene (9,9-Bis (3-fluoro-4-aminophenyl) fluoride, FFDA), etc. However, it is not limited to these.

The dianhydride (dianhydride) is pyromellitic acid dianhydride (1,2,4,5-benethetracarboxylic dianhydride, pyromelliticacid dianhydride, PMDA), biphenyltetracarboxylic dianhydride (3,3,4,5-bihydride). In addition to dianhydride (BPDA), other dianhydrides can be included, for example, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), 4- (2,5). −Dioxo tetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride (TDA), benzophenone tetracarboxylic dianhydride (3,3,4,5-Benzophenone) teracarboxylic dianhydride, BTDA), oxydiphthalic dianhydride (4,4-Oxydiphthalic dianhydride, ODPA), biscarboxyphenyldimethylsilane dianhydride (Biz (3,4-dicarboxyphenyl) dimethyl-dimethyl-s phenoxy diphenyl sulfide dianhydride (4,4-bis (3,4-dicarboxyphenoxy ) diphenyl sulfide dianhydride, BDSDA), sulfonyl di phthalic anhydride _{(Sulfonyldiphthalic anhydride, SO 2 DPA)} , cyclobutane tetracarboxylic dianhydride (cyclobutane -1,2,3,4-tetracarboxic dianhydride, CBDA), isopropyridenediphenoxybisphthalic anhydride (4,4'-(4,4'-Isopropylidenediphenoxy) bis (phthical anchor, 6HBDA), etc. However, it is not limited to these.

The polyamic acid of the present invention is a repeating unit derived from bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB), a repeating unit derived from m-phenylenediamine (mPDA), and a pyro. Repetitive units derived from merit acid dianhydride (1,2,4,5-benzene terracarboxylic dianhydride, pyromelliticacid dianhydride, PMDA) and biphenyltetracarboxylic acid dianhydride (3,3,4,5-biphenylbodyBride) When a repeating unit derived from is included, m-phenylenediamine can have a high glass transition temperature, and BPDA can be added to obtain the effect of improving yellowness as compared with PMDA.

The repeating unit derived from the m-phenylenediamine (mPDA) has a content of 10 to 20 mol%, preferably 15 to 20 mol%, based on 100 mol% of the repeating unit derived from the diamine. Can include. When the content of the repeating unit derived from the m-phenylenediamine is less than 10 mol%, the ratio may be relatively small and there is almost no effect on improving the heat resistance, and the m-phenylenediamine may be almost ineffective. When the content of the repeating unit derived from is more than 20 mol%, the yellowness may increase due to the structural characteristics.
The repeating unit derived from the biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA) is 1: 1 to 1.5 with respect to the repeating unit derived from m-phenylenediamine. It can be included in a molar ratio. That is, the molar ratio of the repeating unit derived from m-phenylenediamine to the repeating unit derived from biphenyltetracarboxylic dianhydride (3,3,4,5-biphenyltetracarboxylic dianhydride, BPDA) is 1: 1 to 1.5. It is preferable to include a repeating unit derived from biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA) in terms of content. When the molar ratio of the repeating unit derived from the biphenyltetracarboxylic acid dianhydride is less than 1 molar ratio, the effect of improving the yellowness may be small, and when it exceeds 1.5 molar ratio, the effect of improving the yellowness may be small. Due to the high linear coefficient of thermal expansion, the linear coefficient of thermal expansion of the polyimide composition may increase.

The polyamic acid according to the present invention has, as a repeating unit derived from a diamine, a repeating unit derived from bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and a m-phenylenediamine diamine, In addition to the repeating units derived from mPDA), repeating units derived from bisfluoroaminophenylfluorene (9,9-Bis (3-fluoro-4-aminophenyl) fluororene, FFDA) can be further included.
The polyamic acid of the present invention contains a repeating unit derived from bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and a repeating unit derived from m-phenylenediamine (mPDA). By further containing a repeating unit derived from bisfluoroaminophenylfluorene (9,9-Biz (3-fluoro-4-aminophenyl) fluororene, FFDA), an FFDA raw material having a high glass transition temperature is introduced to increase the glass transition temperature. The effect of further improvement can be obtained.

The repeating unit derived from the bisfluoroaminophenylfluorene (9,9-Biz (3-fluoro-4-aminophenyl) fluororene, FFDA) is 1 to 10 mol% with respect to 100 mol% of the repeating unit derived from diamine. , It is preferably contained in an amount of 1 to 8 mol%, more preferably 1 to 5 mol%. When the content of the bisfluoroaminophenylfluorene is less than 1 mol%, there may be almost no action and effect, and when it exceeds 10 mol%, the mechanical properties of the polyimide film are due to the characteristics of the FFDA raw material. May decrease and the linear coefficient of thermal expansion may increase.
The repeating unit derived from the diamine can contain the repeating unit derived from the m-phenylenediamine and the repeating unit derived from the bisfluoroaminophenylfluorene in a total amount of more than 10 mol% and not more than 20 mol%. When the total amount of the repeating unit derived from the m-phenylenediamine and the repeating unit derived from the bisfluoroaminophenylfluorene is 10 mol% or less, the effect of improving the glass transition temperature physical properties cannot be obtained. If it exceeds 20 mol%, the yellowness and the coefficient of thermal expansion may increase as described above.

According to another embodiment of the present invention, in a polyimide containing a repeating unit derived from a diamine and a repeating unit derived from a dianhydride, the repeating unit derived from the diamine is a repeating unit derived from bistrifluoromethylbenzidine. And the repeating unit derived from m-phenylenediamine, and the repeating unit derived from m-phenylenediamine is 10 to 20 mol%, preferably 15 to 19 with respect to 100 mol% of the repeating unit derived from the diamine. The repeating unit contained in a molar% content and derived from the dianhydride includes a repeating unit derived from pyromellitic acid dianhydride and a repeating unit derived from biphenyltetracarboxylic acid dianhydride, and the repeating unit derived from the biphenyltetra. The repeating unit derived from the carboxylic acid dianhydride can provide a polyimide contained in a molar ratio of 1: 1 to 1.5 with respect to the repeating unit derived from the m-phenylene amine.

The polyimide according to the present invention has, as a repeating unit derived from a diamine, a repeating unit derived from bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and m-phenylenediamine (meta-phenylenedidia, mPDA). ), And the repeating units derived from dianhydride are the repeating units and biphenyls derived from pyromellitic dianhydride (1,2,4,5-benzene terracarboxylic diamine, pyromelliticacid diamine, PMDA). Includes repeating units derived from tetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic diamine, BPDA).

As the diamine, other diamines can be contained in addition to bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and m-phenylenediamine (mPDA). As an example, oxydianiline (4,4'-Oxydianiline, ODA), p-phenylenediamine (para-phenylene diamine, pPDA), p-methylenedianiline (para-Methylene dyaniline, pMDA), m-methylenedianiline (pMDA). meta-Methylene Dianiline, mMDA), bisaminophenoxybenzene (1,3-bis (3-aminophenoxy) aminee, 133APB), bisaminophenoxybenzene (1,3-bis (4-aminophenoxy) aminee, 134APB), bisamino Phenoxyphenylhexafluoropropane (2,2'-bis [4 (4-aminophenoxy) amineyl] hexafluoropropane, 4BDAF), bisaminophenylhexafluoropropane (2,2'-bis (3-aminophenyl) hexafluoropropane, 33-6F) , Bisaminophenyl hexafluoropropane (2,2'-bis (4-aminophenyl) hexafluoropropane, 44-6F), bisaminophenyl sulfone (bis (4-aminophenyl) sulfone, 4DDS), bisaminophenyl sulfone (bis (3) -Aminophenyl) sulfone, 3DDS), cyclohexanediamine (1,3-Cyclohexanediamine, 13CHD), cyclohexanediamine (1,4-Cyclohexanediamine, 14CHD), bisaminophenoxyphenylpropane (2,2-Biz [4- (4-aminophenyloxy)). ) -Amine] probe, 6HMDA), bisaminohydroxyphenylhexafluoropropane (2,2-Biz (3-amino-4-hydroxy-phenyl) -hexafluoropropane, DBOH), bisaminophenoxydiphenylsulfone (4,4'- Bis (3-amino phenoxy) diphenyl sulfone, DBSDA), bisaminophenylfluorene (9,9-Biz (4-aminophenyl) fluororene, FDA), bisfluoroaminophenylfluorene (9,9-Biz (3-fluoro-4) -Aminephenyl) flo uorene, FFDA) and the like, but are not limited thereto.

The dianhydrides are pyromellitic dianhydride (1,2,4,5-benzenetelacarboxyllic dianhydride, pyromelliticacid dianhydride, PMDA), biphenyltetracarboxylic dianhydride (3,3,4,4-biphenylelectric dianhydride, PMDA), and biphenyltetracarboxylic dianhydride. ) Other dianhydrides can be included. As an example, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), 4- (2,5-dioxo tetrahydrofuran-3-yl) -1,2,3,4 -Tetrahydronaphthalene-1,2-dicarboxylic acid anhydride (TDA), benzophenone tetracarboxylic acid dianhydride (3,3,4,5-Benzophenone terracarboxylic dianhydride, BTDA), oxydiphthalic acid dianhydride (4,4-Oxydiphthalic) dianhydride, ODPA), biscarboxyphenyldimethylsilane dianhydride (Bis (3,4-dicarboxyphenyl) dimethyl-silane dianhydride, SiDA), bisdicarboxyphenyloxydiphenylsulfide dianhydride (4,4-bis (3,4-bis)) dicarboxyphenoxy) diphenyl sulfide dianhydride, BDSDA) , sulfonyl di phthalic anhydride _{(Sulfonyldiphthalic anhydride, SO 2 DPA)} , cyclobutane tetracarboxylic dianhydride (cyclobutane-1,2,3,4-tetracarboxylic dianhydride, CBDA), Isopuropiri Examples thereof include, but are not limited to, dendiphenoxybisphthalic anhydride (4,4'-(4,4'-Isopropylidediphenoxy) bis (physical anhydride), 6HBDA).

The polyimide of the present invention is a repeating unit derived from bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB), a repeating unit derived from m-phenylenediamine (mPDA), and pyromerit. Repeating units derived from acid dianhydride (1,2,4,5-benzene terracarboxylic dianhydride, pyromelliticacid dianhydride, PMDA) and biphenyltetracarboxylic acid dianhydride (3,3,4,5-benzylenedihydride) When the derived repeating unit is included, m-phenylenediamine can have a high glass transition temperature, and the addition of BPDA can have the effect of improving yellowness as compared to polyimide.
The repeating unit derived from the m-phenylenediamine (mPDA) has a content of 10 to 20 mol%, preferably 15 to 19 mol%, based on 100 mol% of the repeating unit derived from the diamine. Can be included in. When the content of the repeating unit derived from m-phenylenediamine is less than 10 mol%, the ratio may be relatively small and there is almost no effect on improving the heat resistance, and when it exceeds 20 mol%. In some cases, the yellowness may increase due to its structural characteristics.

The repeating unit derived from the biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA) is 1: 1 to 1.5 with respect to the repeating unit derived from m-phenylenediamine. It can be included in a molar ratio. That is, the molar ratio of the repeating unit derived from m-phenylenediamine to the repeating unit derived from biphenyltetracarboxylic dianhydride (3,3,4,5-biphenyltetracarboxylic dianhydride, BPDA) is 1: 1 to 1.5. It is preferable to contain a repeating unit derived from biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA). When the molar ratio of the repeating unit derived from the biphenyltetracarboxylic dianhydride is less than 1 molar ratio, the effect on improving the yellowness may be small, and when it exceeds 1.5 molar ratio, the effect is small. Due to the high linear coefficient of thermal expansion, the linear coefficient of thermal expansion of the polyimide composition may increase.

The polyimide according to the present invention has a repeating unit derived from bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and m-phenylenediamine (mPDA) as a repeating unit derived from diamine. In addition to the repeating unit derived from bisfluoroaminophenylfluorene (9,9-Biz (3-fluoro-4-aminophenyl) fluororene, FFDA), the repeating unit derived from bisfluoroaminophenylfluorene (FFDA) can be further included.
The polyimide of the present invention contains repeating units derived from bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and repeating units derived from m-phenylenediamine (mPDA), as well as bis. By further containing a repeating unit derived from fluoroaminophenylfluorene (9,9-Biz (3-fluoro-4-aminophenyl) polyimide, FFDA), an FFDA raw material having a high glass transition temperature is introduced to further increase the glass transition temperature. The effect of improvement can be obtained.

The repeating unit derived from the bisfluoroaminophenylfluorene (9,9-Biz (3-fluoro-4-aminophenyl) fluororene, FFDA) is 1 to 10 mol% with respect to 100 mol% of the repeating unit derived from diamine. , It is preferably contained in an amount of 1 to 8 mol%, more preferably 1 to 5 mol%. When the content of the bisfluoroaminophenylfluorene is less than 1 mol%, there is almost no action and effect, and when it exceeds 10 mol%, the mechanical properties of the polyimide film deteriorate due to the characteristics of the FFDA raw material. , The coefficient of linear thermal expansion may increase.
The repeating unit derived from the diamine can contain the repeating unit derived from the m-phenylenediamine and the repeating unit derived from the bisfluoroaminophenylfluorene in a total amount of more than 10 mol% and not more than 20 mol%. When the total amount of the repeating unit derived from the m-phenylenediamine and the repeating unit derived from the bisfluoroaminophenylfluorene is 10 mol% or less, the effect of improving the glass transition temperature physical properties cannot be obtained. In some cases, if it exceeds 20 mol%, the yellowness and the coefficient of thermal expansion may increase as described above.

According to another embodiment of the present invention, a polyimide film containing the above-mentioned polyimide can be provided.
The polyimide film has a coefficient of thermal expansion of 10 ppm / ° C. or lower, 7.79 ppm / ° C. or lower, 6.82 ppm / ° C. or lower, 5.17 ppm / ° C. or lower, 4.72 ppm / ° C. at 50 to 350 ° C. It is preferably ℃ or less.
When the transmittance of the polyimide film is measured with a UV spectrometer based on a thickness of 10 to 100 μm, the transmittance at 550 nm is 85% or more, 86.59% or more, 86.71% or more, 86.92%. , 87.18% or more is preferable. Furthermore, the average transmittance at 380 to 780 nm is 80% or more, and the average transmittance at 550 to 780 nm is 85% or more, 86.59% or more, 86.71% or more, 86.92%, 87. It is preferably 18% or more.
Further, the polyimide film preferably has a yellowness of 15 or less, 14.37 or less, 12.45 or less, 12.15 or less, 11.67 or less based on a film thickness of 10 to 100 μm.
The polyimide film of the present invention satisfying the above-mentioned light transmittance, yellowness and heat resistance is a protective film whose use is restricted by the yellow color of the conventional polyimide film, or a diffuser and coating film in a TFT-LCD or the like, for example. It can be used in fields where transparency is required, such as an interlayer in a polyimide-LCD, a gate insulator, and a liquid crystal alignment film. Further, when the transparent polyimide is applied to the liquid crystal alignment film, it contributes to an increase in the aperture ratio and can manufacture a TFT-LCD having a high contrast ratio. Further, it can also be used as a flexible display substrate (Flexible Display Substrate) and a hard coating film that replace glass in a conventional display.

The above-mentioned physical properties such as coefficient of thermal expansion, transmittance, and yellowness are such that the thickness of the film is in the range of 10 to 100 μm when measured, for example, 11 μm, 12 μm, 13 μm, ... 100 μm. It can be measured using a film having a thickness. When each of the films within the thickness is measured, the range of the physical properties can be satisfied. The thickness range of the film corresponds to the measuring method for measuring the physical properties, and does not mean to limit the thickness of the film unless otherwise specified. Further, the polyimide film according to the present invention is characterized in that it satisfies all the above-mentioned physical characteristics, that is, the ranges such as the coefficient of thermal expansion, the transmittance, and the yellowness.

According to another embodiment of the present invention, it is possible to provide an image display device including the above-mentioned polyimide film.

According to another embodiment of the present invention, a diamine containing bistrifluoromethylbenzidine and m-phenylenediamine is added to a solvent and dissolved to produce a diamine solution (S1), and the diamine is produced in the S1 step. It is possible to provide a method for producing a polyamic acid, which comprises a step (S2) of adding a dianhydride containing a biphenyltetracarboxylic dianhydride and a pyromellitic dianhydride to a diamine solution and reacting the diamine solution.

As the diamine, other diamines can be contained in addition to bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and m-phenylenediamine (meta-phenylene diamine, mPDA). As an example, oxydianiline (4,4'-Oxydianiline, ODA), p-phenylenediamine (para-phenylene diamine, pPDA), p-methylenedianiline (para-Methylene dianiline, pMDA), m-methylenedianiline (pMDA) meta-Methylene Dianiline, mMDA), bisaminophenoxybenzene (1,3-bis (3-aminophenoxy) aminee, 133APB), bisaminophenoxybenzene (1,3-bis (4-aminophenoxy) aminee, 134APB), bisamino Phenoxyphenylhexafluoropropane (2,2'-bis [4 (4-aminophenoxy) amineyl] hexafluoropropane, 4BDAF), bisaminophenylhexafluoropropane (2,2'-bis (3-aminophenyl) hexafluoropropane, 33-6F) , Bisaminophenyl hexafluoropropane (2,2'-bis (4-aminophenyl) hexafluoropropane, 44-6F), bisaminophenyl sulfone (bis (4-aminophenyl) sulfone, 4DDS), bisaminophenyl sulfone (bis (3) -Aminophenyl) sulfone, 3DDS), cyclohexanediamine (1,3-Cyclohexanediamine, 13CHD), cyclohexanediamine (1,4-Cyclohexanediamine, 14CHD), bisaminophenoxyphenylpropane (2,2-Biz [4- (4-aminophenyloxy)). ) -Amine] probe, 6HMDA), bisaminohydroxyphenylhexafluoropropane (2,2-Biz (3-amino-4-hydroxy-phenyl) -hexafluoropropane, DBOH), bisaminophenoxydiphenylsulfone (4,4'- Bis (3-amino phenoxy) diphenyl sulfone, DBSDA), bisaminophenylfluorene (9,9-Biz (4-aminophenyl) fluorene, FDA), bisfluoroaminophenylfluorene (9,9-Biz (3-fluoro-4-)) amineophenyl) fluo rene, FFDA) and the like, but are not limited to these.

The dianhydrides are pyromellitic dianhydride (1,2,4,5-benzenetelacarboxyllic dianhydride, pyromelliticacid dianhydride, PMDA), biphenyltetracarboxylic dianhydride (3,3,4,4-biphenylelectric dianhydride, PMDA), and biphenyltetracarboxylic dianhydride. ) Other dianhydrides can be included. As an example, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), 4- (2,5-dioxo tetrahydrofuran-3-yl) -1,2,3,4 -Tetrahydronaphthalene-1,2-dicarboxylic acid anhydride (TDA), benzophenone tetracarboxylic acid dianhydride (3,3,4,5-Benzophenone terracarboxylic dianhydride, BTDA), oxydiphthalic acid dianhydride (4,4-Oxydiphthalic) dianhydride, ODPA), biscarboxyphenyldimethylsilane dianhydride (Bis (3,4-dicarboxyphenyl) dimethyl-silane dianhydride, SiDA), bisdicarboxyphenyloxydiphenylsulfide dianhydride (4,4-bis (3,4-bis)) dicarboxyphenoxy) diphenyl sulfide dianhydride, BDSDA) , sulfonyl di phthalic anhydride _{(Sulfonyldiphthalic anhydride, SO 2 DPA)} , cyclobutane tetracarboxylic dianhydride (cyclobutane-1,2,3,4-tetracarboxylic dianhydride, CBDA), Isopuropiri Examples thereof include, but are not limited to, dendiphenoxybisphthalic anhydride (4,4'-(4,4'-Isopropylide diphenoxy) bis (physical anhydride), 6HBDA).

First, a diamine containing bistrifluoromethylbenzidine and m-phenylenediamine is added to a solvent and dissolved to prepare a diamine solution (S1).
In the S1 step, the m-phenylenediamine can be added in an amount of 10 to 20 mol%, preferably 15 to 20 mol%, based on 100 mol% of the diamine. When the content of the repeating unit derived from m-phenylenediamine is less than 10 mol%, the ratio may be relatively small and there is almost no effect on improving the heat resistance, and when it exceeds 20 mol%. In some cases, the yellowness may increase due to its structural characteristics.
When the diamine solution is produced in the S1 step, in addition to bistrifluoromethylbenzidine (2,2'-bis (trifluoromethyl) benzidine, TFDB) and m-phenylenediamine (meta-phenylene diamine, mPDA), bisfluoroamino Phenylfluorene (9,9-Biz (3-fluoro-4-aminophenyl) fluoride, FFDA) can be further added.
The bisfluoroaminophenylfluorene can be further added in a content of 1 to 10 mol%, preferably 1 to 8 mol%, more preferably 1 to 5 mol% with respect to 100 mol% of the diamine. When the content of the bisfluoroaminophenylfluorene is less than 1 mol%, there may be almost no action and effect, and when it exceeds 10 mol%, the mechanical properties of the polyimide film are due to the characteristics of the FFDA raw material. May decrease and the linear coefficient of thermal expansion may increase.
When the diamine solution is produced in the S1 step, the m-phenylenediamine and the bisfluoroaminophenylfluorene can be added in a total amount of more than 10 mol% and not more than 20 mol%. When the total amount of the m-phenylenediamine and the bisfluoroaminophenylfluorene is 10 mol% or less, the glass transition temperature may not be improved, and when it exceeds 20 mol%, as described above. Yellowness and coefficient of thermal expansion may increase.

The solvents used are m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), acetone, diethylacetate, diethylformamide (DEF), diethylacetamide. One or more polar solvents selected from (DEA), PGME (Propyrene glycol monoacetamide), and PGMEA (Propyrene glycol monoacetamide) are used. In addition, a low boiling point solution such as tetrahydrofuran (THF) or chloroform or a low absorption solvent such as γ-butyrolactone can be used. Not limited to this, such a solvent can be used alone or in combination of two or more depending on the purpose.
Although not particularly limited with respect to the content of the solvent, the content of the solvent is preferably 70 to 95% by weight, more preferably 75 to 95% by weight, based on the total diamine solution, for the degree of polymerization and the convenience of the process. 90% by weight.

Next, a dianhydride containing biphenyltetracarboxylic dianhydride and pyromellitic dianhydride is added to the diamine solution produced in the step S1 and reacted (S2).
In the S2 step, the biphenyltetracarboxylic dianhydride is preferably added in a molar ratio of 1: 1 to 1.5 with respect to the repeating unit derived from the m-phenylenediamine. That is, biphenyltetracarboxylic dianhydride having a molar ratio of m-phenylenediamine to biphenyltetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA) of 1: 1 to 1.5. It is preferable to add a substance (3,3,4,4-Bifenelyltetracarboxylic anhydride, BPDA).
When the content of the biphenyltetracarboxylic acid dianhydride is less than 1 molar ratio, the effect of improving the yellowness may be small, and when it exceeds 1.5 molar ratio, a high linear coefficient of linear thermal expansion Therefore, the linear coefficient of thermal expansion of the polyimide composition may increase.
The conditions for the reaction in the S2 step are not particularly limited, but the reaction temperature is preferably 0 to 80 ° C., and the reaction time is preferably 2 to 48 hours. Further, it is more preferable to have an atmosphere of an inert gas such as argon or nitrogen during the reaction.
In the S2 step according to the present invention, biphenyltetracarboxylic dianhydride is added to the diamine solution produced in the S1 step for a primary reaction, and then pyromellitic dianhydride is added for a secondary reaction. It is more preferable to let it.
The primary reaction in the S2 step is preferably carried out at 25 to 30 ° C. for 3 to 5 hours. When the primary reaction is carried out under the above conditions, it has an effect that a sufficient reaction can be carried out for the progress of polyamic acid polymerization.
The secondary reaction in the S2 step is preferably carried out at 25 to 40 ° C. for 12 to 20 hours. When the primary reaction is carried out under the above conditions, it has an effect that a sufficient reaction can be carried out for the progress of polyamic acid polymerization.

The method for producing the polyimide film from the polyamic acid obtained by the above-mentioned production method is not particularly limited, and a conventionally known method can be used. Examples of the method for imidizing the polyamic acid include a thermal imidization method and a chemical imidization method, but it is more preferable to use the chemical imidization method. More preferably, the solution subjected to the chemical imidization method is precipitated, purified and dried, and then further dissolved in a solvent for use. This solvent is the same as the solvent described above. In the chemical imidization method, a dehydrating agent typified by an acid anhydride such as acetic anhydride and an imidization catalyst typified by tertiary amines such as isoquinoline, β-picoline, and pyridine are applied to a polyamic acid solution. It is a way to make it. The thermal imidization method can be used in combination with the chemical imidization method, and the heating conditions can vary depending on the type of polyamic acid solution, the thickness of the film, and the like.
After the chemical imidization method, it is precipitated, dried, dissolved in a solvent, made into a solution and applied to the support, and the applied solution is formed into a film on the support by dry air and heat treatment. The film formation temperature condition of the applied film is preferably 300 to 500 ° C., and glass, aluminum foil, a circulating stainless belt, a stainless drum, or the like can be used as the support.
The treatment time required for film formation depends on the temperature, the type of support, the amount of the polyamic acid solution applied, and the mixing conditions of the catalyst, and is not limited to a fixed time. It is preferably carried out in the range of 5 to 30 minutes.
The heat treatment temperature is 100 to 500 ° C., and the treatment time is 1 minute to 30 minutes. After heat treatment to complete drying and imidization, it is peeled off from the support.
The residual volatile content of the heat-treated film is 5% or less, preferably 3% or less.
The thickness of the obtained polyimide film is not particularly limited, but is preferably in the range of 10 to 100 μm.

Hereinafter, the present invention will be described in more detail by way of examples, but the scope of the present invention is not limited to the following examples.
<Example 1>
Filling with 278.606 g of N-methyl-2-pyrrolidone (NMP) while passing nitrogen through a 500 ml reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler as a reactor, TFDB28 After dissolving 180 g (0.088 mol), 2.379 g (0.022 mol) of mPDA was dissolved. Then, 9.709 g (0.033 mol) of BPDA was added and reacted for 4 hours, and 16.795 g (0.077 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. Then, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Example 2>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, 274.519 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB28. After dissolving 180 g (0.088 mol), 2.379 g (0.022 mol) of mPDA was dissolved. Then, 6.473 g (0.022 mol) of BPDA was added and reacted for 4 hours, and 19.195 g (0.088 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Example 3>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler as a reactor, 276.002 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB28. After dissolving 180 g (0.088 mol), 2.379 g (0.0209 mol) of mPDA and 0.423 g (0.0011 mol) of FFDA were dissolved. Then, 6.473 g (0.022 mol) of BPDA was added and reacted for 4 hours, and 19.195 g (0.088 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Example 4>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler as a reactor, 281.938 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB28. After dissolving 180 g (0.088 mol), 1.784 g (0.0165 mol) of mPDA and 2.114 g (0.0055 mol) of FFDA were dissolved. Then, 6.473 g (0.022 mol) of BPDA was added and reacted for 4 hours, and 19.195 g (0.088 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative example 1>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, 272.910 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB26 After dissolving .419 g (0.0825 mol), 2.974 g (0.0275 mol) of mPDA was dissolved. Then, 9.709 g (0.033 mol) of BPDA was added and reacted for 4 hours, and 16.795 g (0.077 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative example 2>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, 295.691 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB33. After dissolving .464 g (0.1045 mol), 0.595 g (0.0055 mol) of mPDA was dissolved. Then, 9.709 g (0.033 mol) of BPDA was added and reacted for 4 hours, and 16.795 g (0.077 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative example 3>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler as a reactor, 272.475 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB28. After dissolving 180 g (0.0088 mol), 2.379 g (0.022 mol) of mPDA was dissolved. Then, 4.855 g (0.0165 mol) of BPDA was added and reacted for 4 hours, and 20.394 g (0.0935 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative example 4>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, TFDB28 was filled with 280.649 g of N-methyl-2-pyrrolidone (NMP). After dissolving 180 g (0.088 mol), 2.379 g (0.022 mol) of mPDA was dissolved. Then, 11.327 g (0.0385 mol) of BPDA was added and reacted for 4 hours, and PMDA 15.596 (0.0715 mol) 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative example 5>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, 284.301 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB29. After dissolving .942 g (0.0935 mol), 1.784 g (0.0165 mol) of mPDA was dissolved. Then, 9.709 g (0.033 mol) of BPDA was added and reacted for 4 hours, and 16.795 g (0.077 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative Example 6>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, 289.996 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB31 was used. After dissolving .703 g (0.099 mol), 1.190 g (0.011 mol) of mPDA was dissolved. Then, 9.709 g (0.033 mol) of BPDA was added and reacted for 4 hours, and 16.795 g (0.077 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative Example 7>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, 270.432 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB28 was added. After dissolving 180 g (0.088 mol), 2.379 g (0.022 mol) of mPDA was dissolved. Then, 3.236 g (0.011 mol) of BPDA was added and reacted for 4 hours, and PMDA21.594 (0.099 mol) 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative Example 8>
After filling 289.357 g of N-methyl-2-pyrrolidone (NMP) while passing nitrogen through a 500 ml reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler as a reactor. , TFDB 28.180 g (0.088 mol) was dissolved, and mPDA 1.190 g (0.011 mol) and FFDA 4.229 g (0.011 mol) were dissolved. Then, 6.473 g (0.022 mol) of BPDA was added and reacted for 4 hours, and 19.195 g (0.088 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative Example 9>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, 293.328 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB31 was added. After dissolving .703 g (0.099 mol), 0.595 g (0.0055 mol) of mPDA and 2.114 g (0.0055 mol) of FFDA were dissolved. Then, 6.473 g (0.022 mol) of BPDA was added and reacted for 4 hours, and 19.195 g (0.088 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative Example 10>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, 296.775 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB28. After dissolving 180 g (0.088 mol), 0.595 g (0.0055 mol) of mPDA and 6.343 g (0.0165 mol) of FFDA were dissolved. Then, 6.473 g (0.022 mol) of BPDA was added and reacted for 4 hours, and 19.195 g (0.088 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative Example 11>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler as a reactor, 276.242 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB26. After dissolving .419 g (0.0825 mol), 2.379 g (0.022 mol) of mPDA and 2.114 g (0.0055 mol) of FFDA were dissolved. Then, 6.473 g (0.022 mol) of BPDA was added and reacted for 4 hours, and 19.195 g (0.088 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative Example 12>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, 274.519 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB28. After dissolving 180 g (0.088 mol), 2.379 g (0.022 mol) of pPDA was dissolved. Then, 6.473 g (0.022 mol) of BPDA was added and reacted for 4 hours, and 19.195 g (0.088 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

<Comparative Example 13>
While passing nitrogen through a 500 ml reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler as a reactor, 281.938 g of N-methyl-2-pyrrolidone (NMP) was filled and TFDB28. After dissolving 180 g (0.088 mol), 1.784 g (0.0165 mol) of pPDA and 2.114 g (0.0055 mol) of FFDA were dissolved. Then, 6.473 g (0.022 mol) of BPDA was added and reacted for 4 hours, and 19.195 g (0.088 mol) of PMDA 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 completion of the reaction, the obtained solution was applied to a glass plate, treated with hot air at 80 ° C. for 20 minutes, and cured to 350 ° C. After that, it was gradually cooled and separated from the glass plate to obtain a polyimide film.

The physical characteristics of the polyimide films produced in the above Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Table 1 below.
(1) Measurement of transmittance The transmittance at 550 nm was measured three times using a UV spectrometer (manufactured by Konica Minolta, CM-3700d), and the average value thereof is shown in Table 1.
(2) Measurement of yellowness (YI) The yellowness was measured according to the ASTM E313 standard using a UV spectrometer (manufactured by Konica Minolta, CM-3700d).
(3) Measurement of Coefficient of Thermal Expansion (CTE) The linear coefficient of thermal expansion at 50 to 350 ° C. was measured twice based on TMA-Measure using TMA (manufactured by TA Instrument, Q400). The size of the test piece was 4 mm × 24 mm, the load was 0.02 N, and the heating rate was 10 ° C./min.
Since the film is formed and the residual stress may remain in the film by heat treatment, the residual stress is completely removed by the first operation (Run), and then the second value is presented as the measured value. ..
(4) Measurement of glass transition temperature (Tg) Using MA (manufactured by TA Instrument, Q400), the size of the test piece is 4 mm × 24 mm, the load is 0.02 N, and the temperature rise rate is 10 ° C./min to 370. It was measured by observing up to ° C.

（注釈）
比較例１２：ジアミンのモノマーをＴＦＤＢ及びｐＰＤＡとし、二無水物をＰＭＤＡ及びＢＰＤＡとした。
比較例１３：ジアミンのモノマーをＴＦＤＢ、ｐＰＤＡ及びＦＦＤＡとし、二無水物をＰＭＤＡ及びＢＰＤＡとした。

(Note)
Comparative Example 12: Diamine monomers were TFDB and pPDA, and dianhydrides were PMDA and BPDA.
Comparative Example 13: Diamine monomers were TFDB, pPDA and FFDA, and dianhydrides were PMDA and BPDA.

As shown in Table 1, the content of mPDA preferably does not exceed 20 mol% in order to prevent a decrease in yellowness, and in the case of FFDA, it has an effect of improving the glass transition temperature, but also increases CTE. Therefore, it is appropriate that the content is within 10 mol%. In the case of BPDA, the desired content varies depending on the proportion of the diamine added first, but it is judged that it is preferable to add it within 30 mol% as a whole. If it is more than that, it can be seen that the yellowness is improved, but the CTE and the glass transition temperature are lowered.
To explain this concretely, Comparative Example 1 has a problem that the proportion of mPDA is high and CTE increases, whereas Comparative Example 2 has a problem that the proportion of mPDA is low and the glass transition temperature is improved. In contrast, Comparative Examples 3 and 7 have a problem that the proportion of BPDA is lower and the yellowness is higher than the proportion of mPDA, whereas Comparative Examples 4 to 6 have a problem that the proportion of mPDA is higher than that of mPDA. There is a problem that the ratio of BPDA is high and the CTE and the glass transition temperature are lowered. Further, it can be seen that Comparative Examples 8 to 11 had a problem that the ratio of the raw materials was not appropriate and the CTE or the glass transition temperature was lowered, respectively.
From Comparative Examples 12 and 13, it can be seen that when pPDA is used instead of mPDA as the diamine, the optical characteristics are lowered and the effect of improving the glass transition temperature is lowered.
From this, it can be seen that in order to satisfy all the physical properties of transmittance, yellowness, coefficient of thermal expansion and glass transition temperature, the configuration of the present invention must be satisfied as in Examples 1 to 4.

The present invention can be used as a material for a polyamic acid, a polyimide, a polyimide film, and an image display device containing the same.

Claims (8)

In polyamic acids containing repeating units derived from diamines and repeating units derived from dianhydrides.
Repeating units derived from the diamine comprises repeating units derived from a bis-trifluoromethyl benzidine, repeating units derived from the repeating unit, and bisfluoromethyl aminophenylfluorene from m- phenylenediamine,
Repeating units derived from prior Symbol m- phenylenediamine is included in a content of 10 to 20 mol% relative to the repeating unit 100 mole% derived from the diamine,
The repeating unit derived from the bisfluoroaminophenylfluorene is contained in an amount of 1 to 10 mol% with respect to 100 mol% of the repeating unit derived from the diamine.
The repeating unit derived from the diamine contains the total amount of the repeating unit derived from the m-phenylenediamine and the repeating unit derived from the bisfluoroaminophenylfluorene in an amount of more than 10 mol% and 20 mol% or less.
The repeating unit derived from the dianhydride includes a repeating unit derived from pyromellitic dianhydride and a repeating unit derived from biphenyltetracarboxylic dianhydride.
The repeating unit derived from the biphenyltetracarboxylic dianhydride is a polyamic acid contained in a molar ratio of 1: 1 to 1.5 with respect to the repeating unit derived from the m-phenylrange amine. In a polyimide containing a repeating unit derived from a diamine and a repeating unit derived from a dianhydride.
Repeating units derived from the diamine comprises repeating units derived from a bis-trifluoromethyl benzidine, repeating units derived from the repeating unit, and bisfluoromethyl aminophenylfluorene from m- phenylenediamine,
Repeating units derived from prior Symbol m- phenylenediamine is included in a content of 10 to 20 mol% relative to the repeating unit 100 mole% derived from the diamine,
The repeating unit derived from the bisfluoroaminophenylfluorene is contained in an amount of 1 to 10 mol% with respect to 100 mol% of the repeating unit derived from the diamine.
The repeating unit derived from the diamine contains the total amount of the repeating unit derived from the m-phenylenediamine and the repeating unit derived from the bisfluoroaminophenylfluorene in an amount of more than 10 mol% and 20 mol% or less.
The repeating unit derived from the dianhydride includes a repeating unit derived from pyromellitic dianhydride and a repeating unit derived from biphenyltetracarboxylic dianhydride.
The repeating unit derived from the biphenyltetracarboxylic dianhydride is a polyimide contained in a molar ratio of 1: 1 to 1.5 with respect to the repeating unit derived from m-phenylenediamine. A polyimide film containing the polyimide according to claim 2. An image display device including the polyimide film according to claim 3. A step (S1) of producing a diamine solution by adding a diamine containing bistrifluoromethylbenzidine , m-phenylenediamine and bisfluoroaminophenylfluorene to a solvent and dissolving the diamine.
A step (S2) of adding a dianhydride containing a biphenyltetracarboxylic dianhydride and a pyromellitic dianhydride to the diamine solution produced in the step S1 and reacting the diamine solution is included.
In the step (S1),
The pre-Symbol m- phenylenediamine were added at 10 to 20 mol% relative to diamine 100 mol%,
The bisfluoroaminophenylfluorene was added in an amount of 1 to 10 mol% based on 100 mol% of the diamine.
When the diamine solution is produced in the step (S1), the total amount of the m-phenylenediamine and the bisfluoroaminophenylfluorene is added in an amount of more than 10 mol% and 20 mol% or less.
A method for producing a polyamic acid, in which the biphenyltetracarboxylic dianhydride is added in the step (S2) at a molar ratio of 1: 1 to 1.5 with respect to the repeating unit derived from the m-phenylenediamine. In the step (S2), biphenyltetracarboxylic dianhydride is added to the diamine solution produced in the step (S1) for a primary reaction, and then pyromellitic dianhydride is added for a secondary reaction. The method for producing a polyamic acid according to claim 5. The method for producing a polyamic acid according to claim 6 , wherein the primary reaction in the step (S2) is carried out at 25 to 30 ° C. for 3 to 5 hours. The method for producing a polyamic acid according to claim 6 , wherein the secondary reaction in the step (S2) is carried out at 25 to 40 ° C. for 12 to 20 hours.