JPH07102087A - Production of high-birefringence polyimide film - Google Patents

Abstract

PURPOSE:To obtain a film which exhibits birefringence higher than that of a spin-coat film by vapor-depositing and polymerizing monomers for a polyimide on a substrate of which the surface structure has anisotropy and two-fold symmetry. CONSTITUTION:A substrate of which the surface structure has anisotropy and two-fold symmetry [e.g. Si(111)] is suitable for preparing a film with a high birefringence in the plane direction; a substrate having a homogeneous and flat surface structure, for preparing a film with a high birefringence in the thickness direction. A high birefringence is obtd. by vapor-depositing and polymerizing monomers for a polyimide on the substrate in a vacuum of 1X10<-7>Torr or lower. The monomers are a tetracarboxylic acid or its deriv. and a diamine, and any of the monomers subliming in vacuum without decomposing may be used, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane being an example.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high birefringence polyimide film, and more particularly to a method for producing a high birefringence polyimide film including a step of depositing and polymerizing a raw material monomer of polyimide on a substrate.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a polyimide film having a high birefringence in the in-plane direction, for example, an acid dianhydride and a diamine are reacted in a polar organic solvent such as N, N-dimethylformamide to prepare a polyamide film. Make an acid solution,
Spin coating a polyamic acid solution on a silicon substrate,
A method has been proposed in which a polyamic acid film is obtained, and then the film is peeled from a substrate and stretched while being subjected to heat treatment to obtain a highly birefringent polyimide film. A commercially available polyimide film has been subjected to a stretching treatment, and the birefringence in the in-plane direction is 0.016 for a product name Upilex film manufactured by Ube Industries, Ltd. having a thickness of 20 μm.

[0003]

However, the above-mentioned method for producing a film by stretching has a problem that a release film needs to be used and cannot be easily formed. Further, depending on the type of polyimide, there is a problem that the film is easily broken during the stretching process. Further, as a method for producing a polyimide film with high birefringence in the film thickness direction, a method of producing a film with a rigid molecular structure of a polyimide raw material has been proposed, but for a polyimide of a certain molecular formula An effective method for increasing the birefringence in the film thickness direction has not been proposed. Therefore, with respect to the birefringence in the film thickness direction, if the molecular formula of polyimide is determined, the value of birefringence is also almost determined.
Here, the birefringence in the film thickness direction is the difference between the refractive index when polarized light parallel to the polyimide film surface is incident and the refractive index when vertically polarized light is incident. An object of the present invention is to solve the above problems and provide a method for producing a highly birefringent polyimide film.

[0004]

SUMMARY OF THE INVENTION The present invention will be outlined. The first invention is an invention relating to a method for producing a high-birefringence polyimide film, wherein a polyimide raw material monomer is polymerized on a substrate to synthesize a polyimide. In the method for producing a film, the substrate is a substrate having anisotropy in the surface structure, and the polyimide raw material monomer is vapor-deposited,
It is characterized by being polymerized. The second invention of the present invention is
It is an invention relating to another method for producing a high birefringence polyimide film, wherein in the method for producing a polyimide film in which a polyimide raw material monomer is polymerized on a substrate to synthesize polyimide, the substrate is a substrate having an amorphous structure, and the polyimide It is characterized in that a raw material monomer is vapor-deposited and polymerized.

As a result of intensive studies on the method for producing a highly birefringent polyimide film, the present inventors have found that the birefringence of polyimide can be increased by carrying out vacuum vapor deposition polymerization, and the present invention was completed. I arrived.

It is important to select the type of substrate used for vapor deposition,
For the production of a film having a large birefringence in the in-plane direction, one having an anisotropic surface structure and further having 2-fold symmetry is suitable, and for producing a film having a large birefringence in the film thickness direction. Is preferably flat and has a uniform surface structure. In addition, it is desirable to consider the target value of birefringence and the adhesiveness between the polyimide film and the substrate, etc., and to select one that meets the appropriate conditions.

The production conditions may be changed according to the desired birefringence value, but in order to obtain a large birefringence, the degree of vacuum when evaporating the monomer and polymerizing it on the substrate is 1 A vacuum degree of not more than × 10 ^-7 Torr is desirable. Further, it is desirable that the growth rate is as slow as possible, and it is desirable to produce a film under high vacuum and low speed conditions.

The raw material monomer of the polyimide used in the present invention may be any tetracarboxylic acid or its derivative and diamine, as long as it can be sublimated without decomposition in vacuum.

Examples of the tetracarboxylic acid include the following. (Trifluoromethyl) pyromellitic acid, di (trifluoromethyl) pyromellitic acid, di (heptafluoropropyl) pyromellitic acid, pentafluoroethylpyromellitic acid, bis {3,5-di (trifluoromethyl) phenoxy} Pyromellitic acid, 2, 3,
3 ', 4'-biphenyltetracarboxylic acid, 3,3',
4,4'-tetracarboxydiphenyl ether, 2,
3 ', 3,4'-tetracarboxydiphenyl ether, 3,3', 4,4'-benzophenone tetracarboxylic acid, 2,3,6,7-tetracarboxynaphthalene,
1,4,5,7-tetracarboxynaphthalene, 1,
4,5,6-tetracarboxynaphthalene, 3,3 ',
4,4'-tetracarboxydiphenylmethane, 3,
3 ', 4,4'-tetracarboxydiphenyl sulfone, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 5,5 ′ -Bis (trifluoromethyl) -3,3 ′, 4,4′-tetracarboxybiphenyl, 2,2 ′, 5,5′-tetrakis (trifluoromethyl) -3,3 ′, 4,4′- Tetracarboxybiphenyl, 5,5'-bis (trifluoromethyl) -3,3 ', 4,4'-tetracarboxydiphenyl ether, 5,5'-bis (trifluoromethyl)-
3,3 ′, 4,4′-tetracarboxybenzophenone, bis {(trifluoromethyl) dicarboxyphenoxy} benzene, bis {(trifluoromethyl) dicarboxyphenoxy} (trifluoromethyl) benzene,
Bis (dicarboxyphenoxy) (trifluoromethyl) benzene, bis (dicarboxyphenoxy) bis (trifluoromethyl) benzene, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene, 3,4,9,10-tetra Carboxyperylene,
2,2-bis {4- (3,4-dicarboxyphenoxy) phenyl} propane, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, 2,2-bis {4-
(3,4-dicarboxyphenoxy) phenyl} hexafluoropropane, bis {(trifluoromethyl) dicarboxyphenoxy} biphenyl, bis {(trifluoromethyl) dicarboxyphenoxy} bis (trifluoromethyl) biphenyl, bis {( Trifluoromethyl)
Dicarboxyphenoxy} diphenyl ether, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl, bis (3,4-dicarboxyphenyl) dimethylsilane, 1,3-bis (3,4-dicarboxyphenyl) tetramethyldi Siloxane, difluoropyromellitic acid, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene,
1,4-bis (3,4-dicarboxytrifluorophenoxy) octafluorobiphenyl and the like.

Examples of the diamine include the following. m-phenylenediamine, 2,4-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodurene, 4- (1H, 1H, 11H-eicosafluoroundecanoxy) -1,3-diaminobenzene, 4-
(1H, 1H-perfluoro-1-butanoxy) -1,
3-diaminobenzene, 4- (1H, 1H-perfluoro-1-heptanoxy) -1,3-diaminobenzene,
4- (1H, 1H-perfluoro-1-octanoxy)
-1,3-diaminobenzene, 4-pentafluorophenoxy-1,3-diaminobenzene, 4- (2,3,
5,6-Tetrafluorophenoxy) -1,3-diaminobenzene, 4- (4-fluorophenoxy) -1,3
-Diaminobenzene, 4- (1H, 1H, 2H, 2H-
Perfluoro-1-hexanoxy) -1,3-diaminobenzene, 4- (1H, 1H, 2H, 2H-perfluoro-1-dodecanoxy) -1,3-diaminobenzene,
p-phenylenediamine, 2,5-diaminotoluene,
2,3,5,6-Tetramethyl-p-phenylenediamine, 2,5-diaminobenzotrifluoride, bis (trifluoromethyl) phenylenediamine, diaminotetra (trifluoromethyl) benzene, diamino (pentafluoroethyl) benzene 2,5-diamino (perfluorohexyl) benzene, 2,5-diamino (perfluorobutyl) benzene, benzidine, 2,2'-
Dimethylbenzidine, 3,3'-dimethylbenzidine,
3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3 ', 5,5'-tetramethylbenzidine, 3,3'-diacetylbenzidine, 2,2'-
Bis (trifluoromethyl) -4,4'-diaminobiphenyl, octafluorobenzidine, 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 4,4 ′
-Diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 2,2-bis (p-aminophenyl)
Propane, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,2-bis (anilino) ethane, 2,2-bis (p- Aminophenyl) hexafluoropropane, 1,3-bis (anilino) hexafluoropropane, 1,4-bis (anilino) octafluorobutane, 1,5-bis (anilino) decafluoropentane, 1,7-bis (anilino) ) Tetradecafluoroheptane, 2,2'-bis (trifluoromethyl) -4,
4'-diaminodiphenyl ether, 3,3'-bis (trifluoromethyl) -4,4'-diaminodiphenyl ether, 3,3 ', 5,5'-tetrakis (trifluoromethyl) -4,4'-diaminodiphenyl ether , 3,3'-bis (trifluoromethyl) -4,4 '
-Diaminobenzophenone, 4,4'-diamino-p-
Terphenyl, 1,4-bis (p-aminophenyl) benzene, p-bis (4-amino-2-trifluoromethylphenoxy) benzene, bis (aminophenoxy) bis (trifluoromethyl) benzene, bis (aminophenoxy) ) Tetrakis (trifluoromethyl) benzene,
4,4 "'-diamino-p-quarterphenyl, 4,
4'-bis (p-aminophenoxy) biphenyl, 2,
2-bis {4- (p-aminophenoxy) phenyl} propane, 4,4'-bis (3-aminophenoxyphenyl) diphenyl sulfone, 2,2-bis {4- (4-aminophenoxy) phenyl} hexafluoro propane,
2,2-bis {4- (3-aminophenoxy) phenyl} hexafluoropropane, 2,2-bis {4- (2
-Aminophenoxy) phenyl} hexafluoropropane, 2,2-bis {4- (4-aminophenoxy)-
3,5-dimethylphenylhexafluoropropane,
2,2-bis {4- (4-aminophenoxy) -3,5
-Ditrifluoromethylphenyl} hexafluoropropane, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-
Amino-3-trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) diphenyl sulfone, 4,4'-bis (3-amino-5-trifluoromethylphenoxy) Diphenyl sulfone, 2,2-bis {4- (4-amino-
3-trifluoromethylphenoxy) phenyl} hexafluoropropane, bis {(trifluoromethyl) aminophenoxy} biphenyl, bis [{(trifluoromethyl) aminophenoxy} phenyl] hexafluoropropane, diaminoanthraquinone, 1,5-diamino Naphthalene, 2,6-diaminonaphthalene, bis {2-
[(Aminophenoxy) phenyl]} hexafluoroisopropylbenzene, bis {(2,3,5,6) -tetrafluoro-4-aminophenyl} sulfide, 1,3
-Bis (3-aminopropyl) tetramethyldisiloxane, 1,4-bis (3-aminopropyldimethylsilyl) benzene, bis (4-aminophenyl) diethylsilane, 1,3-diaminotetrafluorobenzene, 1,
4-diaminotetrafluorobenzene, 4,4'-bis (tetrafluoroaminophenoxy) octafluorobiphenyl and the like.

FIG. 1 shows an example of a sectional view of an apparatus for producing a highly birefringent polyimide film of the present invention. Reference numeral 1 denotes a growth chamber, and the inside of the growth chamber 1 is a vacuum exhaust system 2 of an external vacuum pump. And a substrate holder 4 for forming a vapor deposition film of a polyimide resin in the growth chamber 1
So that the substrate 3 can be heated to a desired temperature by a heater 5 provided on the back surface of the substrate holder 4,
Further, the film thickness formed on the substrate 3 is measured by the film thickness monitor 6 installed near the substrate 3. Further, effusion cells 7 and 8 are provided below the inside of the growth chamber 1 so as to face the substrate 3 and evaporate the raw material monomer of the polyimide resin. Further, the evaporation rate from each monomer was measured by the film thickness monitors 9 and 10 installed near the effusion cell, and the crucible temperature of the effusion cell was fed back. 11 and 12 in the figure
Indicates a shutter in front of each crucible, and by opening and closing this, vapor deposition of the substance in the crucible on the substrate is turned on and off. Thirteen
Indicates a shutter on the front surface of the substrate. A liquid nitrogen shroud 14 prevents the re-evaporation of the monomer from the inner wall of the growth chamber.

[0012]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples.

Example 1 First, as a substrate, a Si (111) substrate 3 which is an anisotropic substrate and has two-fold symmetry is mounted on a substrate holder 4, and one of the effusion cells is provided with 2,2-bis (3). , 4-Dicarboxyphenyl) hexafluoropropane dianhydride (a) and on the other hand 2,2'-bis (trifluoromethyl)
It is filled with -4,4'-diaminobiphenyl (b), and the total pressure of the atmosphere gas in the growth chamber 1 is evacuated to 1 × 10 ^-8 Torr using the exhaust system 2 with the shutters 11, 12, and 13 closed. Pull. Further, the liquid nitrogen shroud 14 is filled with liquid nitrogen so that the degree of vacuum is 5 × 10 ⁻⁹ Torr or less. Then, while measuring the evaporation rates of the respective raw material monomers a and b from the effusion cell with the film thickness monitors 6, 9 and 10, a is set to 120 ° C. ± 0.5 ° C. and b is set to 65 ° C. ± 0.5 ° C. To heat. Next, after the raw material monomers a and b reach the target temperature and the required evaporation rate is obtained, the shutters 11 and 12,
13 is opened, and the raw material monomers a and b are set to 6 nm / on the substrate 3.
It was deposited to a thickness of 1 μm at a growth rate of min. After that, the shutters 11, 12, and 13 are closed, and the substrate 3 is heated to a temperature of 350 ° C. by the heater 5 and held for a predetermined time to hold the substrate 3
A polyimide polymerization reaction was caused to form a polyimide film on the substrate 3, and the refractive index was examined. As a result, the difference between the maximum refractive index and the minimum refractive index in the direction parallel to the film was 0.002. In addition, a flat and uniform film having an area of 2 inches φ was obtained.

Comparative Example 1 In order to compare with Example 1 described above, a polyimide film was prepared by the spin coating method using the same substrate and monomer as in Example 1. The film thickness is 1 μm. As a result of measuring the refractive index of the film, the difference between the maximum refractive index and the minimum refractive index in the direction parallel to the film was 0.000.

Example 2 First, a silicon substrate 3 with an oxide film having an amorphous structure was mounted on a substrate holder 4 as a substrate, and 2,2-bis (3,4-dicarboxyphenyl) hexafluoro was added to one of the effusion cells. Propane dianhydride (a) and the other side were filled with 4,4'-oxydianiline (b), and while the shutters 11, 12, and 13 were closed, the total pressure of the atmosphere gas in the growth chamber 1 was adjusted to the exhaust system 2. Vacuum is applied to 1 × 10 ⁻⁸ Torr. Further, the liquid nitrogen shroud 14 is filled with liquid nitrogen so that the degree of vacuum is 5 × 10 ⁻⁹ Torr or less. Then, while measuring the evaporation rate of each raw material monomer a, b from the effusion cell with the film thickness monitors 6, 9, 10
Heat to 20 ° C ± 0.5 ° C and b to 80 ° C ± 0.5 ° C. Then, after the raw material monomers a and b reach the target temperature and the required evaporation rate is obtained, the shutters 11, 12, and 1 are released.
3 is opened, and the raw material monomers a and b are 6 nm / mi on the substrate 3.
It was deposited to a thickness of 1.5 μm at a growth rate of n 2. After that, the shutters 11, 12, and 13 are closed and the substrate 3 is heated by the heater 5
While maintaining the temperature at 350 ° C. for a predetermined time, a polyimide polymerization reaction is caused on the substrate 3 to form a polyimide film having a thickness of 1.5 μm on the substrate 3.
The refractive index at 3 nm was investigated. As a result, the difference in refractive index between the direction parallel to the film surface and the direction perpendicular to the film surface was 0.0187. In addition, a flat and uniform film having an area of 2 inches φ was obtained.

Comparative Example 2 For comparison with Example 2, a polyimide film was prepared by the spin coating method using the same substrate and monomer as in Example 2. The film thickness is 1.5 μm. As a result of measuring the refractive index of the film, the difference in refractive index between the direction parallel to the film surface and the direction perpendicular to the film surface was 0.0078.

[0017]

As described above, according to the present invention, when a polyimide film is manufactured by a method of forming a polyimide film by depositing and polymerizing a polyimide raw material monomer in a vacuum, a polyimide film having the same molecular formula is spin-coated. It has an effect that a film having a birefringence larger than that of the film can be produced. Further, since there is no need to peel off the film at the time of manufacturing, there is an effect that the film can be manufactured without a problem of breakage.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of an apparatus for producing a high birefringence polyimide film of the present invention.

[Explanation of symbols]

1: growth chamber, 2: vacuum exhaust system, 3: substrate, 4: substrate holder, 5: heater, 6: substrate-side film thickness monitor, 7 and 8:
Efusion cell, 9 and 10: film thickness monitor on effusion cell, 11 and 12: shutter on effusion cell, 13: shutter on substrate, 14: liquid nitrogen shroud

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Sawada 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A method for producing a polyimide film, comprising synthesizing polyimide by polymerizing a polyimide raw material monomer on a substrate, wherein the substrate is a substrate having an anisotropic surface structure, and the polyimide raw material monomer is deposited and polymerized. A method for producing a high birefringence polyimide film, comprising: 2. The method for producing a high birefringence polyimide film according to claim 1, wherein the substrate is a substrate having a two-fold symmetry. 3. A method for producing a polyimide film, in which a polyimide raw material monomer is polymerized on a substrate to synthesize polyimide, wherein the substrate is a substrate having an amorphous structure, and the polyimide raw material monomer is vapor-deposited and polymerized. Highly birefringent polyimide film manufacturing method.