JPH1192559A - Production of polyimide for optical component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyimide having a constant loss of optical transmission by reacting a tetracarboxylic acid dianhydride having a specified or higher purity with a diamine having a specified or higher purity. SOLUTION: A tetracarboxylic acid dianhydride (e.g. pyromellitic dianhydride or (trifluoromethyl)pyromellitic dianhydride) having a purity of 95% or higher and diaminodiphenyl ether or 2,2'-bis(trifluoromethyl)-4,4'-diaminoethyl having a purity of 95% or higher, at least either of which must be a fluoro compound, are dissolved in a diamine/tetracarboxylic acid molar ratio of 1/(0.95-1.05) in a polar solvent such as N,N-dimethylacetamide. Next, the solution is subjected to a reaction at 0-50 deg.C to produce a solution of a polyimide precursor having a weight average molecular weight of 10,000-1,000,000. This solution is applied to an optical substrate such as made of glass, and the wet film is heated to 150-400 deg.C to effect closure into imide rings, dried and cured to obtain a polyimide film.

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 polyimide used for optical parts such as optical waveguides, optical filters and light transmitting films.

[0002]

2. Description of the Related Art Polyimide has excellent heat resistance among organic materials and is resistant to various organic solvents. Therefore, polyimide requires a high-temperature manufacturing process. It is used for substrates for applications. Utilizing this feature, it is used for optical components requiring heat resistance. In order to use a polyimide for an optical component, it is necessary to improve the optical characteristics. As a method for this, a method using a polyimide containing a fluorine atom as shown in JP-A-3-72528 is used. Are known. Polyimide used for optical components is generally a polyimide solution obtained by dissolving a polyimide obtained by imidizing a polyamic acid solution or a polyamic acid solution, which is a precursor solution of the polyimide, in an organic solvent, by applying such as spin coating or casting, This is formed by heat curing. A polyamic acid solution, which is a polyimide precursor solution, is generally obtained by a synthesis process in which an acid dianhydride monomer and a diamine monomer are reacted and polymerized in an organic solvent as raw materials.

[0003] The characteristics of the polyimide formed by such a method are affected by the state of the polyimide precursor solution and the curing conditions of the film. Among the various properties, the important optical properties for optical components vary greatly, and the birefringence is controlled by controlling the polymer molecular weight in the polyimide precursor solution, or by changing the type of organic solvent used for the solvent. The refractive index and the light transmission loss can be changed, and the refractive index and the light transmission loss can be controlled to some extent by the curing temperature, time, atmosphere or curing device of the film. However, the polyimide precursor solution has a problem in that the characteristic value, particularly the value of the optical transmission loss, does not become constant every time it is synthesized, and sometimes shows a large value.

[0004]

An object of the present invention is to provide a polyimide for an optical component having a constant characteristic value, in particular, a value of optical transmission loss, for an optical component capable of producing a stable and high yield. A method for producing a polyimide is provided.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a polyimide for optical parts, comprising reacting a tetracarboxylic dianhydride having a purity of 95 mol% or more with a diamine having a purity of 95 mol% or more.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyimide for optical parts of the present invention is
The polyimide precursor can be obtained by imide ring closure in a conventional manner. The polyimide precursor is N-methyl-2-pyrrolidone, N, N-dimethylacetamide, γ
-Synthesized by reacting a diamine with a tetracarboxylic dianhydride using a polar organic solvent such as butyrolactone or dimethyl sulfoxide as a solvent. At this time, the ratio of the diamine and the tetracarboxylic dianhydride used was 0.9 mol of the tetracarboxylic dianhydride with respect to 1 mol of the diamine.
The amount is preferably 5 to 1.05 mol from the viewpoint of increasing the molecular weight, and more preferably 1 mol. The reaction temperature at this time is usually 0 to 50 ° C., and the reaction time is usually 0.1.
The range is 5 to 50 hours. Further, the synthesized solution of the polyimide precursor is subjected to pressure filtration with a filter having a hole diameter of 0.2 to 20 μm at a pressure of 0.1 to 10 atm to remove foreign substances mixed during the synthesis.

The organic solvent used as the solvent preferably has a purity of 96 mol% or more, more preferably 99 mol% or more, in order to prevent impurities from being mixed in and to suppress the reaction due to impurities such as water. . The weight average molecular weight (GPC measurement, standard polystyrene conversion) of the polyimide precursor synthesized in this way is preferably 10,000 to 1,000,000 from the viewpoint of strength and handleability, and 100,000 to 100,000. More preferably, it is 400,000.

In the present invention, the purity of the tetracarboxylic dianhydride and the diamine used as the raw materials must both be 95% by weight or more, preferably 98% by mole or more, and more preferably 99% by mole or more. Is more preferable. When the purity is less than 95% by weight, it becomes impossible to stably produce polyimide for optical parts having a constant characteristic value, particularly a value of optical transmission loss, with a high yield. The purity of the tetracarboxylic dianhydride and diamine used as raw materials affects the optical transmission loss of the formed polyimide,
If the purity is low, the optical transmission loss increases due to impurities remaining in the polyimide film and the formation of chromophore substituents due to heating during film formation, and the higher the purity, the higher the purity of the polyimide formed and the theoretical light It decreases to near the limit value of the transmission loss.

The impurities contained in the tetracarboxylic dianhydride and the diamine used as the raw materials include, for diamine, dirt, isomers having different bonding positions of amino groups, alkali metals such as lithium, sodium and potassium, platinum and the like. Noble metals, compounds having a monoamine or nitro group, and the like. In the case of tetracarboxylic dianhydride, dust, isomers having different carboxyl bond positions, alkali metals such as lithium, sodium, potassium, platinum, etc. Noble metals, non-anhydrideized tetracarboxylic acids and fluorinated but not fluorinated tetracarboxylic acids, tricarboxylic acids, dicarboxylic acids,
Monocarboxylic acids and the like can be mentioned. The methods for measuring the purity of tetracarboxylic dianhydride and diamine include differential scanning calorimetry (DSC) measurement, mass spectrum, and nuclear magnetic resonance (NM).
R) Measurement, liquid chromatography, gas chromatography and the like.

As a method for increasing the purity of tetracarboxylic dianhydride, there is a method of recrystallization using an organic solvent such as acetic anhydride.
Examples include recrystallization using an organic solvent such as n-butanol and ethyl alcohol, and distillation under reduced pressure. The type of the tetracarboxylic dianhydride and the diamine used in the present invention is not particularly limited, but from the viewpoint of improving transparency, at least one of the tetracarboxylic dianhydride and the diamine contains a compound containing fluorine. Preferably, it is used.

Examples of the tetracarboxylic dianhydride containing fluorine include (trifluoromethyl) pyromellitic dianhydride, di (trifluoromethyl) pyromellitic dianhydride and di (heptafluoropropyl) pyromellitic Acid dianhydride, pentafluoroethyl pyromellitic dianhydride, bis {3,5-di (trifluoromethyl) phenoxy} pyromellitic dianhydride, 2,2-bis (3,4
-Dicarboxyphenyl) hexafluoropropane dianhydride, 5,5'-bis (trifluoromethyl) -3,
3 ', 4,4'-tetracarboxybiphenyl dianhydride, 2,2'-5,5'-tetrakis (trifluoromethyl) -3,3', 4,4'-tetracarboxybiphenyl dianhydride, , 5'-bis (trifluoromethyl)
-3,3 ', 4,4'-tetracarboxydiphenyl ether dianhydride, 5,5'-bis (trifluoromethyl) -3,3', 4,4'-tetracarboxybenzophenone dianhydride, bis {( Trifluoromethyl) dicarboxyphenoxy {benzene dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} (trifluoromethyl) benzene dianhydride, bis (dicarboxyphenoxy) (trifluoromethyl) benzene dianhydride, Bis (dicarboxyphenoxy) bis (trifluoromethyl) benzene dianhydride, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene dianhydride, 2,2-bis {(4- (3,4-dicarboxy) Phenoxy) phenyl @ hexafluoropropane dianhydride,
Bis {(trifluoromethyl) dicarboxyphenoxy} biphenyl dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} bis (trifluoromethyl) biphenyl dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} diphenyl ether Dianhydride, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl dianhydride and the like.

As the diamine containing fluorine, for example,
4- (1H, 1H, 11H-eicosafluoroundecanooxy) -1,3-diaminobenzene, 4- (1H, 1
H-perfluoro-1-butanoxy) -1,3-diaminobenzene, 4- (1H, 1H-perfluoro-1-heptanoxy) -1,3-diaminobenzene, 4- (1
H, 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, (2,
5) -Diaminobenzotrifluoride, bis (trifluoromethyl) phenylenediamine, diaminotetra (trifluoromethyl) benzene, diamino (pentafluoroethyl) benzene, 2,5-diamino (perfluorohexyl) benzene, 2,5- Diamino (perfluorobutyl) benzene, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,3'-
Bis (trifluoromethyl) -4,4'-diaminobiphenyl, octafluorobenzidine, 4,4'-diaminodiphenyl ether, 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, 2,2-bis {4- (4-aminophenoxy) phenyl} hexafluoropropane, 2,2-bis {4- (3-aminophenoxy) phenyl} hexa Fluoropropane, 2,2-bis {4- (2-aminophenoxy) phenyl} hexafluoropropane, 2,2-
Bis {4- (4-aminophenoxy) -3,5-dimethylphenyl} hexafluoropropane, 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) diphenylsulfone, 4,4'-bis (3-amino-5-trifluoromethylphenoxy) diphenylsulfone, 2,2-bis {4- (4 -Amino-3-trifluoromethylphenoxy) phenyl} hexafluoropropane, bis {(trifluoromethyl) aminophenoxy} biphenyl, bis [{(trifluoromethyl) aminophenoxy} phenyl] hexafluoropropane,
Bis {2-[(aminophenoxy) phenyl] hexafluoroisopropyl} benzene and the like.

Examples of the tetracarboxylic dianhydride containing no fluorine include, for example, p-terphenyl-3,4,
3 ", 4" -tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetra Carboxylic dianhydride, 3,3 ', 4,4'-biphenylethertetracarboxylic dianhydride, 1,2,2
5,6-naphthalenetetracarboxylic dianhydride, 2,
3,6,7-naphthalenetetracarboxylic dianhydride,
2,3,5,6-pyridinetetracarboxylic dianhydride,
1,4,5,8-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, 3,
3 ', 4,4'-tetraphenylsilanetetracarboxylic dianhydride, meta-terphenyl-3,3 ", 4,4"
-Tetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylethertetracarboxylic dianhydride, 1,3-
Bis (3,4-dicarboxyphenyl) -1,1,3
3-tetramethyldisiloxane dianhydride, 1- (2,3
-Dicarboxyphenyl) -3- (3,4-dicarboxyphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride. When a polyamideimide resin is obtained, usually trimellitic anhydride chloride or the like is used.

Examples of the diamine containing no fluorine include 4,4'-diaminodiphenyl ether and 4,4 '
-Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, benzine, methanephenylenediamine, paraphenylenediamine, 2,2-bis- (4-aminophenoxyphenyl) propane, 1,5 -Naphthalenediamine,
2,6-naphthalenediamine, bis- (4-aminophenoxyphenyl) sulfone, bis- (4-aminophenoxyphenyl) sulfide, bis- (4-aminophenoxyphenyl) biphenyl, 1,4-bis- (4-amino Phenoxy) benzene, 1,3-bis- (4-aminophenoxy) benzene, 3,4′-diaminodiphenyl ether, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-dimethoxy-4, 4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether-
3-sulfonamide, 3,4'-diaminodiphenylether-4-sulfonamide, 3,4'-diaminodiphenylether-3'-sulfonamide, 3,3'-diaminodiphenylether-4-sulfonamide, 4,
4'-diaminodiphenylmethane-3-sulfonamide, 3,4'-diaminodiphenylmethane-4-sulfonamide, 3,4'-diaminodiphenylmethane-3 '
-Sulfonamide, 3,3'-diaminodiphenylmethane-4-sulfonamide, 4,4'-diaminodiphenylsulfone-3-sulfonamide, 3,4'-diaminodiphenylsulfone-4-sulfonamide, 3,4'-
Diaminodiphenylsulfone-3'-sulfonamide,
3,3'-diaminodiphenylsulfone-4-sulfonamide, 4,4'-diaminodiphenylsulfide-
3-sulfonamide, 3,4'-diaminodiphenylsulfide-4-sulfonamide, 3,3'-diaminodiphenylsulfide-4-sulfonamide, 3,
4'-diaminodiphenylsulfide-3'-sulfonamide, 1,4-diaminobenzene-2-sulfonamide, 4,4'-diaminodiphenylether-3-carbonamide, 3,4'-diaminodiphenylether-4-carbonamide 3,4'-diaminodiphenyl ether-3'-carbonamide, 3,3'-diaminodiphenyl ether-4-carbonamide, 4,4'-
Diaminodiphenylmethane-3-carbonamide, 3,
4'-diaminodiphenylmethane-4-carbonamide, 3,4'-diaminodiphenylmethane-3'-carbonamide, 3,3'-diaminodiphenylmethane-4
-Carbonamide, 4,4'-diaminodiphenylsulfone-3-carbonamide, 3,4'-diaminodiphenylsulfone-4-carbonamide, 3,4'-diaminodiphenylsulfone-3'-carbonamide, 3,
3'-diaminodiphenylsulfone-4'-carbonamide, 4,4'-diaminodiphenylsulfide-3
-Carbonamide, 3,4'-diaminodiphenylsulfide-4-carbonamide, 3,3'-diaminodiphenylsulfide-4-carbonamide, 3,4 '
-Diaminodiphenylsulfide-3'-sulfonamide, 1,4-diaminobenzene-2-carbonamide and the like. The above-mentioned tetracarboxylic dianhydride and diamine are used alone or in combination of two or more.

The solution of the polyimide precursor is applied to a semiconductor substrate such as silicon or gallium arsenide or an optical substrate such as quartz or glass by a spin coating method, a printing method, or the like, and is heated by a heating device such as a hot plate or an oven. Fifteen
The polyimide film for optical parts of the present invention can be formed by imide ring closure, drying and curing at a temperature of 0 to 400 ° C. These films are patterned as necessary by a method such as wet etching, dry etching, or laser ablation, and are formed into a predetermined shape to become optical components. Examples of the optical component include a lens, an optical waveguide, an optical splitter, an optical multiplexer, an optical switching device, an optical modulator, an optical filter, a wavelength divider, an optical amplifier, an optical attenuator, a wavelength converter, and an optical circuit. .

[0016]

【Example】

Example 1 As a tetracarboxylic dianhydride, 2,2-bis (3,4
-Dicarboxyphenyl) hexafluoropropanoic acid dianhydride (6FDA) was used to form a polyimide using paraphenylenediamine (PPD) as a diamine as a raw material, and the optical transmission loss was measured. 6FDA with a purity of 94.3 mol%, which had not been recrystallized, was recrystallized using acetic anhydride to obtain a high-purity monomer. Further, PPD having a purity of 93.8 mol%, which had not been recrystallized, was recrystallized using butanol to obtain a high-purity monomer. The purity of each of these high-purity monomers is 99.5 mol% for 6FDA,
PD was 99.0 mol%. The purity of the monomer was determined by DuPont's 9900 Computer / ThermalAnalyzer.
System; Version 6.0 DSC DYNAMIC from DuPont
CALORIMETRICPURITY DATA ANALYSIS PROGRAM; Version
It measured using what installed 1.0.

In the synthesis, 170.0 g of 99.9 mol% N, N-dimethylacetamide as a solvent was added to 99.0 mol% P in a 0.5 liter flat bottom flask.
5.88 g of PD was dissolved, and 24.12 g of 6FDA having a purity of 99.5 mol% was added thereto.
After stirring for 0 hour, a polyimide precursor solution having a viscosity of about 20 Pa.s was obtained. Next, the precursor solution was applied on a quartz wafer having a diameter of 4 inches by a spin coating method.
3 minutes at 00 ° C., then 30 minutes at 200 ° C., then 350
The polyimide was heated at 60 ° C. for 60 minutes in the air to close the imide, dried and cured to form a polyimide film having a thickness of about 4 μm. Optical transmission loss is measured by a light scattering method that uses a semiconductor laser with a wavelength of 830 nm to use a polarizing filter to enter TM-mode light into the film through a prism and calculate the light loss from the distance from the prism and the intensity of the scattered light. Was measured. As a result, it was confirmed that the optical transmission loss was 0.5 dB / cm in both the TE mode and the TM mode, which was good for optical components.

COMPARATIVE EXAMPLE 1 Using PPD having a purity of 93.8 mol% without recrystallization, 6FDA and N, N-dimethylacetamide were prepared using the same raw materials as in Example 1 and polyimide in the same manner as in Example 1. A precursor solution was synthesized. The viscosity of this precursor solution was 3.8 Pa.s. When this polyimide precursor solution was evaluated in the same manner as in Example 1, the optical transmission loss was inferior at 2.3 dB / cm in both the TE mode and the TM mode.

[0019]

According to the method for producing a polyimide for an optical component according to the first aspect, it is possible to produce a polyimide for an optical component having a constant characteristic value, particularly a constant optical transmission loss, with a high yield. It is.

Claims (1)

[Claims] 1. A process for producing a polyimide for optical parts, comprising reacting a tetracarboxylic dianhydride having a purity of 95 mol% or more with a diamine having a purity of 95 mol% or more.