JP5834574B2 - Method for purifying 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride powder and polyimide using the same - Google Patents

Description

  The present invention relates to a method for purifying 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride powder with little coloring, and a polyimide using the same. Here, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder is mainly composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and is substantially 3 , 3 ′, 4,4′-biphenyltetracarboxylic dianhydride is a powder suitably used as a chemical raw material.

  With the advent of an advanced information society, development of optical materials such as a liquid crystal alignment film and a protective film for a color filter in the display device field, such as an optical fiber and an optical waveguide in the optical communication field, is progressing. Further, in the field of display devices, a lightweight and flexible plastic substrate has been studied as an alternative to a glass substrate, and a display that can be bent and rolled using the plastic substrate has been developed.

  Polyimide is a resin obtained from a tetracarboxylic acid component and a diamine component, and has excellent properties such as high dimensional stability and high heat resistance, so that application development as a high-performance optical material is desired. However, polyimide is not only easily colored due to its chemical structure, but also it is not easy to suppress coloring in the raw material tetracarboxylic acid component and diamine component.

One of the raw materials for the tetracarboxylic acid component of polyimide is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.
Patent Document 1 discloses that a 3,3 ′, 4,4′-biphenyltetracarboxylic acid heat-dehydrated product is heated and melted and then kept at 307 ° C. or higher while maintaining the oxygen concentration in the system at 10 ppm or lower under reduced pressure. It is described that 3,3 ′, 4,4′-biphenyltetracarboxylic acid heat-dehydrated product with less coloration is obtained by evaporating at a temperature of 330 ° C. or less, cooling the vapor and crystallizing. .

  In Patent Document 2, 3,3 ′, 4,4′-biphenyltetracarboxylic acid is specified using a specific heating device, with a maximum pressure within a range of 210 ° C. to 250 ° C. under a specific pressure condition. The mixture is heated at a temperature rising rate of 150 ° C. and kept at 150 ° C. to 250 ° C. for a specific time to obtain a 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride by dehydration cyclization. 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride was further purified by sublimation purification under reduced pressure at a temperature of 250 [deg.] C. or higher to give less colored 3,3', 4,4'-biphenyl. Obtaining a tetracarboxylic acid heat-dehydrated product is described.

  Patent Document 3 discloses biphenyltetracarboxylic acid anhydride comprising hydrolyzing and dehydrating tetramethyl 3,3 ′, 4,4′-biphenyltetracarboxylate, adding an adsorbent in a solvent, filtering, and recrystallizing. A purification method of the product is described, and it is described that acetic anhydride is suitable as a solvent used for recrystallization.

JP 2005-314296 A JP 2006-45198 A JP 2004-196687 A

According to the production methods of Patent Documents 1 and 2, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride with little coloring is obtained. However, the production methods of Patent Documents 1 and 2 are large-scale devices such as an apparatus for evaporating at a high temperature under a specific oxygen concentration atmosphere under reduced pressure after heating and melting, or a heating apparatus having a special structure for dehydration. Equipment was necessary and there was a problem in terms of equipment cost. In addition, there is a problem that complicated operation is required under severe operating conditions, and improvement has been demanded.
In the production method of Patent Document 3, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride with reduced alkali metal is obtained. However, recrystallization with acetic anhydride was not sufficient in reducing the coloring.

The present invention does not require large-scale equipment, and easily obtains 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder with little coloration by a method by simple operation under mild conditions. As a result of various investigations on possible purification methods.
That is, the present invention does not require large-scale equipment, and easily obtains 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder with little coloration by a method by a simple operation under mild conditions. Providing a purification method that can be used, and obtaining a polyimide having good permeability by using 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder with little coloration obtained by the purification method With the goal.

The present invention relates to the following items.
1. A solvent having a solubility at 25 ° C. in 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride of 0.1 g / 100 g or more, and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride The powder is mixed in an inhomogeneous state in which at least a portion of the 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder is not dissolved, and then undissolved 3,3 ′ from the mixture. A method for purifying 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride dianhydride powder, which comprises separating and recovering 4,4′-biphenyltetracarboxylic dianhydride powder.

2. The 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride having a solubility of 25 ° C. in the solvent is 1 g / 100 g or more, A method for purifying 4'-biphenyltetracarboxylic dianhydride powder.

3. 3. The 3,3 ′ according to item 1 or 2, wherein the solvent is N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone. , 4,4′-biphenyltetracarboxylic dianhydride powder purification method.

4). Light transmittance of a wavelength of 400 nm and an optical path length of 1 cm with respect to a solution obtained by dissolving the separated and recovered 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder in a 2N aqueous sodium hydroxide solution at a concentration of 10% by mass. Item 3. The method for purifying 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder according to any one of Items 1 to 3, wherein the ratio is 75% or more.

5. The 3,3 ′, 4,4 according to any one of Items 1 to 4, wherein the 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder separated and recovered is further sublimated. Purification method of '-biphenyltetracarboxylic dianhydride powder.

6). The tetracarboxylic acid component is composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder separated and recovered by the purification method according to any one of Items 1 to 5, and the diamine component is a fat. A film thickness of 10 μm composed of a diamine selected from the group consisting of aromatic diamines, diamines having an alicyclic structure, and aromatic diamines having a substituent of any one of a halogen group, a carbonyl group and a sulfonyl group A polyimide characterized by having a light transmittance of 80% or more at 400 nm when the film is formed.

7． Item 7. The polyimide according to Item 6, which is used as an optical material.

8). A tetracarboxylic acid component comprising the 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder separated and recovered by the purification method according to any one of Items 1 to 5, an aliphatic diamine, Polymerization imidization of diamines having an alicyclic structure and diamine components composed of diamines selected from the group consisting of aromatic diamines having a substituent of any one of a halogen group, a carbonyl group and a sulfonyl group A method for producing polyimide, comprising:

  According to the present invention, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder with little coloration can be easily obtained by a method by simple operation under mild conditions without requiring large-scale equipment. Possible purification methods can be provided. Further, the 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder with little coloration obtained by the purification method of the present invention is used for a high-performance optical material having good transparency, particularly flexible. A polyimide that can be suitably used for a transparent substrate in a display device such as a display or a touch panel can be provided.

In the following description, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is s-BPDA, and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder is s-BPDA powder. , Sometimes abbreviated.
The method for purifying 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder of the present invention comprises a solvent having a solubility at 25 ° C. in s-BPDA of 0.1 g / 100 g or more, and a raw material s-BPDA. The powder is mixed in a non-uniform state where at least a part of the s-BPDA powder is not dissolved, and then the undissolved s-BPDA powder is separated and recovered from the mixed solution.

Here, the solvent having a solubility of s-BPDA at 25 ° C. of 0.1 g / 100 g or more means that 0.1 g or more of s-BPDA is dissolved in 100 g of the solvent at 25 ° C.
In the present invention, the solubility of s-BPDA was measured by the following method.
That is, 5.0 g of s-BPDA powder having a purity of 99% or more and 50.0 g of the solvent are mixed and stirred at 25 ° C. for 3 hours to obtain a mixed solution. (It was confirmed in advance that the mixture would be saturated under the stirring conditions. If not saturated, the amount of the powder was increased to 2 times, 3 times, etc.) The undissolved s-BPDA powder in this mixed solution A filter paper 5A manufactured by Advantech Co., Ltd. is used for filtration, and a saturated solution of s-BPDA is obtained as the filtrate. 5 g of this saturated solution of s-BPDA is weighed in a petri dish and heated at 80 ° C. for 1 hour and then at 200 ° C. for 1 hour to remove the solvent. The mass of s-BPDA of the petri dish after heating is determined, and the solubility at 25 ° C. is calculated from the value.

  As a solvent used in the purification method of the present invention, the solubility of s-BPDA at 25 ° C. is 0.1 g / 100 g or more, preferably 1.0 g / 100 g or more, more preferably 2.0 g / 100 g or more, preferably 100. A solvent of 0.0 g / 100 g or less, more preferably 30.0 g / 100 g or less can be suitably used. If the solubility is low, it is difficult to obtain s-BPDA powder with little coloration. If the solubility is high, s-BPDA powder with little coloration can be obtained, but the raw material is excessively dissolved and the recovery rate is lowered, so that it is not economical. This solvent does not need to be a single type of solvent, and may be a mixture of a plurality of types of solvents as long as the solubility as a mixture is 0.1 g / 100 g or more.

  The solvent used in the present invention is not particularly limited, but for example, aliphatic hydrocarbons such as n-hexane, cyclohexane, heptane and octane, aromatic hydrocarbons such as benzene, toluene and xylene, methanol, Alcohols such as ethanol, butanol, isopropyl alcohol, normal propyl alcohol, butanol, tertiary butanol, butanediol, ethylhexanol, benzyl alcohol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, ethyl acetate, Methyl acetate, butyl acetate, methoxybutyl acetate, cellosolve acetate, amyl acetate, normal propyl acetate, isopropyl acetate, methyl lactate, ethyl lactate, butyl lactate, γ-valerolac , Δ-valerolactone, γ-caprolactone, ε-caprolactone, esters such as α-methyl-γ-butyrolactone, dimethyl ether, ethyl methyl ether, diethyl ether, furan, dibenzofuran, oxetane, tetrahydrofuran, tetrahydropyran, methyl cellosolve, Cellosolve, butyl cellosolve, dioxane, methyl tertiary butyl ether, butyl carbitol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, 3-methoxy-3-methyl- 1-butanol, ethylene glycol monomethyl ether acetate, propylene Glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, ethers such as diethylene glycol monoethyl ether acetate, nitriles such as acetonitrile, propionitrile, butyronitrile, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, Amides such as N-dimethylacetamide, sulfones such as dimethyl sulfoxide, carbonates such as dimethyl carbonate and diethyl carbonate, phenols such as m-cresol, p-cresol, 3-chlorophenol, 4-chlorophenol, etc. Examples include acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, water and the like. Preferred examples include dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone. In a solvent having a solubility of less than 0.1 g / 100 g, the solubility of the mixture can be set to 0.1 g / 100 g or more in combination with a solvent having a solubility of 0.1 g / 100 g or more. In the case of using alcohols or water, it may react with an acid anhydride to cause a ring-opening reaction. Therefore, it is preferable to perform a heat treatment after purification. In order to avoid the heat treatment after purification, these solvents are preferably high-purity solvents that do not contain moisture or alcohol.

  In the present invention, the cause of coloring of the s-BPDA powder is mixed by mixing a solvent having an appropriate solubility and the s-BPDA powder in an uneven state in which at least a part of the s-BPDA powder is not dissolved. By selectively dissolving in a solvent and separating and recovering undissolved s-BPDA powder with reduced coloring, the s-BPDA powder with reduced coloring can be easily obtained in high yield.

  That is, the mixed liquid obtained here is mixed with a solvent in an amount exceeding the solubility of s-BPDA powder, a part of which is dissolved, but the remaining powder is an undissolved mixed liquid in a non-uniform mixed state. It is. Therefore, the mixing ratio of the solvent and the s-BPDA powder may be a ratio in which the s-BPDA powder exceeds the solubility at the temperature of the mixed liquid mixture (preferably at 25 ° C.). A ratio of about 5000 times, more preferably 5 to 2000 times, still more preferably 5 to 200 times, and particularly preferably about 5 to 100 times is suitable. If the amount is too small, the ratio of dissolution and recovery cannot be increased, which is not economical. If the amount is too large, the purification effect may be insufficient.

  In the purification method of the present invention, the temperature at which the solvent and the s-BPDA powder are mixed is preferably a relatively low temperature below the boiling point of the solvent. Specifically, it is 150 degrees C or less, Preferably it is 100 degrees C or less, More preferably, it is less than 70 degreeC, More preferably, it is 0-50 degreeC. It is particularly preferable to carry out at a room temperature of 0 to 50 ° C. without heat treatment. When heated to a high temperature or refluxed, the solvent may react, decompose, or oxidatively deteriorate and become colored. In addition, at high temperatures, the s-BPDA powder itself may be colored by oxidation or the like.

  The mixed solution is preferably stirred by a stirring device. The stirring time is not particularly limited as long as the purification effect is sufficiently obtained. In the present invention, the solution portion in the mixed solution is not necessarily saturated, and it is sufficient that a part of the powder is dissolved to improve the coloring. The stirring time is usually about 0.5 to 6 hours.

  The raw material s-BPDA powder used in the purification method of the present invention is not limited, and conventionally known s-BPDA powder can be suitably used. For example, it may be manufactured by a method for manufacturing s-BPDA described in Patent Documents 1 and 2, or may be manufactured by other known manufacturing methods. In order to be suitably used as a chemical raw material immediately after purification, a material having a purity of 98% by mass or more, preferably 99% by mass or more, more preferably 99.5% by mass or more is suitable. There is no particular limitation on the particle diameter and the form of the particles. Usually, it is a powder having a particle diameter of 5 mm or less, preferably about 1 mm or less. Further, there is no particular limitation on the crystallinity (crystallinity) of the powder.

In the purification method of the present invention, preferably, the mixed solution is sufficiently stirred, and then the undissolved s-BPDA powder in the mixed solution is separated from the solvent and recovered. By this separation, the cause of coloring is separated together with the solvent, and the s-BPDA powder with little coloring can be suitably recovered. As a method for separating and recovering undissolved s-BPDA powder from the mixed solution, known methods such as filtration at normal pressure, pressure filtration, suction filtration, and centrifugal filtration can be suitably used. In addition, it is preferable to perform a isolation | separation process on the temperature conditions substantially the same as the time of mixing and stirring of a liquid mixture. When the temperature of the separation step is lower than the temperature at the time of mixing and stirring the mixed solution, the color-causing substance once dissolved in the solvent may be precipitated again to color the s-BPDA powder.
A solvent is adhered and remains on the separated and recovered s-BPDA powder. For this reason, it is preferable to dry sufficiently by a known method such as hot air drying, heat drying, vacuum drying, etc., preferably in an inert atmosphere. In addition, a part of the acid anhydride may cause a ring-opening reaction during the purification process. In that case, it is preferable to close the ring by heating or the like during drying.

In the purification method of the present invention, a solvent having a solubility in s-BPDA at 25 ° C. of 0.1 g / 100 g or more and s-BPDA powder are non-uniform in which at least a part of s-BPDA powder is not dissolved. It is preferable to further sublimate the s-BPDA obtained by mixing in the state and then separating and recovering the undissolved s-BPDA powder from the mixed solution.
This sublimation does not need to be performed under special conditions, and can be suitably performed under conventionally known conditions. As disclosed in Patent Documents 1 and 2, after heating and melting the s-BPDA powder, it may be evaporated at a high temperature of 250 ° C. or higher under reduced pressure, and the vapor may be cooled and crystallized. Moreover, the s-BPDA crystal | crystallization with less coloring can be obtained suitably also by sublimating at comparatively low temperature about 100-250 degreeC, without melt | dissolving by heating. Even if this s-BPDA crystal is solidified, it can be easily pulverized by pulverization.

  By the purification method of the present invention, a large amount of equipment is not required, and a 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder with little coloration can be easily obtained by a method by simple operation under mild conditions. Can be obtained. The obtained s-BPDA powder has a light transmittance at a wavelength of 400 nm of more than 75%, preferably 80% or more with respect to a solution obtained by dissolving it in a 2N aqueous sodium hydroxide solution at a concentration of 10% by mass. is there.

  By using the s-BPDA powder obtained by the purification method of the present invention, it is possible to easily obtain a polyimide that can be suitably used for a high-performance optical material having good permeability.

  Therefore, this invention relates also to the manufacturing method of the following polyimide and a polyimide. That is, the polyimide of the present invention comprises a tetracarboxylic acid component containing 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder separated and recovered by the purification method of the present invention, and the diamine component is A film composed of a diamine selected from the group consisting of aliphatic diamines, diamines having an alicyclic structure, and aromatic diamines having a substituent of any one of a halogen group, a carbonyl group, and a sulfonyl group The polyimide is characterized in that the light transmittance at 400 nm when the film is 10 μm thick is 70% or more.

In the polyimide of the present invention, the tetracarboxylic acid component is a tetracarboxylic acid component other than the s-BPDA powder of the present invention, based on the total molar amount of the tetracarboxylic acid component, preferably 50% or less, preferably 25% or less. Preferably, 10% or less may be used. By using a tetracarboxylic acid component other than s-BPDA, the solubility of the polyimide precursor may be improved and the production may be facilitated.
The tetracarboxylic acid component other than the s-BPDA powder of the present invention is not particularly limited and may be any tetracarboxylic acid component that is employed as a raw material for a normal polyimide, but is aromatic tetracarboxylic dianhydride. Things are preferred. Examples of such tetracarboxylic dianhydrides include 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, and pyromeritole. Acid dianhydride, oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, m- Terphenyl-3,3 ′, 4,4′-tetracarboxylic dianhydride, 4,4 ′-(2,2-hexafluoroisopropylene) diphthalic dianhydride, 2,2′-bis (3 4-dicarboxyphenyl) propanes, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, (1,1 ′: 3 ′, 1 "-terphenyl) -3,3", 4,4 "-teto Lacarboxylic acid dianhydride, 4,4 ′-(dimethylsiladiyl) diphthalic acid dianhydride, 4,4 ′-(1,4-phenylenebis (oxy)) diphthalic acid dianhydride, and the like, more preferably 2 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride and 2,3,3', 4'-biphenyltetracarboxylic dianhydride can be preferably mentioned.

  The diamine component includes aliphatic diamines, diamines having an alicyclic structure, and aromatic diamines having any one of a halogen group, a carbonyl group, and a sulfonyl group (in other words, a halogen group, a carbonyl group as a substituent). And diamines selected from the group consisting of aromatic diamines having any of sulfonyl groups). Here, the diamine is a diamine or a diamine derivative such as diamine or diisocyanate which is usually employed as a raw material for polyimide. The diamine derivative may be a diamine derivative obtained by reacting a diamine with a silylating agent (such as an amide-based silylating agent) for the purpose of imparting reactivity or product solubility.

  Examples of the aliphatic diamines include linear and branched aliphatic diamines such as diaminobutane, diaminopentane, diaminohexane, diaminoheptane, diaminooctane, diaminononane, diaminodecane, diaminoundecane, diaminododecane, and derivatives thereof. It can be illustrated.

  Examples of the diamine having an alicyclic structure include 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 3-methyl-1,4-diaminocyclohexane, 3-methyl-, 3- Aminomethyl-, 5,5-dimethylcyclohexylamine, 1,3-bisaminomethylcyclohexane, bis (4,4'-aminocyclohexyl) methane, bis (3,3'-methyl-4,4'-aminocyclohexyl) Examples include diamines having an alicyclic structure such as methane, bis (aminomethyl) norbornane, bis (aminomethyl) -tricyclo [5,2,1,0] decane, isophoronediamine, 1,3-diaminoadamantane, and derivatives thereof. .

  Examples of aromatic diamines having a substituent of any one of a halogen group, a carbonyl group and a sulfonyl group include 3,5-diaminobenzotrifluoride, 2- (trifluoromethyl) -1,4-phenylenediamine, 5- (Trifluoromethyl) -1,3-phenylenediamine, 1,3-diamino-2,4,5,6-tetrafluorobenzene, 2,2-bis [4- (4-aminophenoxy) phenyl] -hexafluoro Propane, 2,2-bis (3-aminophenyl) 1,1,1,3,3,3-hexafluoropropane, 2,2′-bis- (4-aminophenyl) -hexafluoropropane, 4,4 -Bis (trifluoromethoxy) benzidine, 3,3'-diamino-5,5'-trifluoromethylbiphenyl, 3,3'-diamino-6,6 -Trifluoromethylbiphenyl, 3,3'-bis (trifluoromethyl) benzidine; 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 4,4'-trifluoromethyl-2, 2'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,3-dichloro-4,4'-diaminobiphenyl, 2,2 ', 5,5'- Aromatic diamines having halogen groups such as dichloro-4,4′-diaminobiphenyl and 4,4′-methylene-bis (2-chloroaniline) and derivatives thereof, 4,4′-diaminobenzophenone, 3,3′- Diaminobenzophenone, 4-aminophenyl-4-aminobenzoate, bis (4-aminophenyl) terephthalate, biphenyl- 4,4′-dicarboxylic acid bis (4-aminophenyl) 1,4-bis (4-aminobenzoyloxy) benzene, 1,3-bis (4-aminobenzoyloxy) benzene, 4,4′-diaminobenzani Carbonyls such as N, N-bis (4-aminophenyl) terephthalamide, N, N′-p-phenylenebis (p-aminobenzamide), N, N′-m-phenylenebis (p-aminobenzamide) Group-containing aromatic diamine and derivatives thereof, 3,3′-diaminodiphenylsulfone, 3,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 3,3′-diamino-4,4′-dihydroxydiphenyl Sulfone, O-tolidine sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3- And aromatic diamines having a sulfonyl group such as aminophenoxy) phenyl] sulfone and derivatives thereof.

  Among these diamines, 1,4-diaminocyclohexane, bis (4,4′-aminocyclohexyl) methane, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 4,4′- Diaminodiphenylsulfone and its derivatives are more preferable because the resulting polyimide has excellent transparency and heat resistance, and trans-1,4-diaminocyclohexane and its derivatives are particularly preferable because the resulting polyimide has a low coefficient of thermal expansion. .

  The polyimide of the present invention is characterized by having a light transmittance of 80% or more at 400 nm when a film having a thickness of 10 μm is formed. Therefore, it can be suitably used as an optical material.

The polyimide production method of the present invention comprises a tetracarboxylic acid component comprising 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder separated and recovered by the purification method of the present invention, and an aliphatic group. A diamine component composed of a diamine, a diamine having an alicyclic structure, and a diamine selected from the group consisting of aromatic diamines having a substituent of any one of a halogen group, a carbonyl group, and a sulfonyl group, It is characterized by polymerization imidization.
The method and conditions for polymerization imidation are not particularly limited, and the method and conditions for polymerization imidization employed in conventional polyimide production methods can be suitably employed, but production via a polyimide precursor described below It can be manufactured more easily by the method.

1) Polyamide acid A diamine is dissolved in an organic solvent, and tetracarboxylic dianhydride is gradually added to the solution while stirring. The polyimide precursor is stirred in a range of 0 to 100 ° C. for 1 to 72 hours. Is obtained.

2) Polyamic acid silyl ester A diamine and a silylating agent are reacted in advance to obtain a silylated diamine. If necessary, the diamine silylated by distillation or the like is purified. A polyimide precursor is obtained by dissolving a silylated diamine in a dehydrated solvent, gradually adding tetracarboxylic dianhydride while stirring, and stirring in a range of 0 to 100 ° C. for 1 to 72 hours. Is obtained. If a silylating agent not containing chlorine is used as the silylating agent used here, it is not necessary to purify the silylated diamine, which is preferable. Examples of the silylating agent not containing a chlorine atom include N, O-bis (trimethylsilyl) trifluoroacetamide, N, O-bis (trimethylsilyl) acetamide, and hexamethyldisilazane. Further, N, O-bis (trimethylsilyl) acetamide and hexamethyldisilazane are preferred because they do not contain fluorine atoms and are low in cost. In addition, amine-based catalysts such as pyridine, piperidine and triethylamine can be used in the silylation reaction of diamine in order to accelerate the reaction. This catalyst can be used as it is as a polymerization catalyst for the polyimide precursor.

  Any of the above production methods is suitably performed in an organic solvent, and as a result, a polyimide precursor solution composition can be easily obtained.

  In any of these production methods, the molar ratio of the tetracarboxylic acid component and the diamine component can be arbitrarily set depending on the required viscosity of the polyimide precursor, preferably 0.90 to 1.10, more preferably 0.95 to 1.05.

  Specifically, the organic solvent used in the production method is preferably an aprotic solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide, etc. There is no problem as long as the monomer and the polyimide precursor to be produced are dissolved, and the structure is not particularly limited. Amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, α-methyl-γ -Cyclic ester solvents such as butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, glycol solvents such as triethylene glycol, phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, 4-chlorophenol, Acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide and the like are preferably employed. In addition, other common organic solvents such as phenol, 0-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, ptyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, Tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, terpene, mineral spirit, Petroleum naphtha solvents can also be used.

  In the present invention, the polyimide precursor solution composition may contain a chemical imidizing agent (an acid anhydride such as acetic anhydride or an amine compound such as pyridine or isoquinoline), an antioxidant, a filler, a dye, an inorganic as necessary. Pigments, silane coupling agents, flame retardants, antifoaming agents, leveling agents, rheology control agents (flow aids), release agents and the like can be added.

  The polyimide of the present invention can be produced by subjecting a polyimide precursor to a dehydration ring-closing reaction (imidation reaction). The imidization method is not particularly limited, and known thermal imidization and chemical imidization methods can be applied. The form of the obtained polyimide can mention a film, a polyimide laminated body, a powder, a bead, a molded object, a foam, a varnish, etc. suitably.

As an example, a polyimide / substrate laminate and a method for producing a polyimide film will be described below.
For example, a polyimide precursor solution composition is cast on a substrate such as ceramic (glass, silicon, alumina), metal (copper, aluminum, stainless steel), heat-resistant plastic film (polyimide), and an inert gas such as nitrogen in a vacuum. It is dried at 20 to 180 ° C., preferably 20 to 150 ° C. using hot air or infrared rays in the air or in the air. Next, the obtained polyimide precursor is peeled off on the substrate or the polyimide precursor (film), and the film end is fixed, in vacuum, in an inert gas such as nitrogen, or in air, A polyimide / substrate laminate or a polyimide film can be produced by heating at 200 to 500 ° C., more preferably 250 to 450 ° C., using hot air or infrared rays. In order to prevent the resulting polyimide from being oxidized and deteriorated, it is desirable to perform imidization in a vacuum or in an inert gas. If the imidization temperature is not too high, it may be carried out in air.

  The imidation reaction may be performed by immersing the polyimide precursor in a solution containing a dehydrating cyclization reagent such as acetic anhydride in the presence of a tertiary amine such as pyridine or triethylamine instead of the heat treatment as described above. Is possible. In addition, a partially imidized polyimide precursor is prepared by previously charging and stirring these dehydrating cyclization reagents in a polyimide precursor solution composition, and casting and drying it on a substrate. It is also possible to obtain a polyimide / substrate laminate or a polyimide film by further heat-treating it as described above.

  This polyimide film or polyimide / substrate laminate is required to have transparency as a material by forming a ceramic thin film or metal thin film on the surface of the polyimide, for example, a transparent substrate for display, a transparent substrate for touch panel, It can be suitably used as a transparent substrate for solar cells.

  Hereinafter, the present invention will be further described by way of examples. In addition, this invention is not limited to a following example.

The raw materials used in the following examples are as follows.
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (s-BPDA): Ube Industries, Ltd. purity 99.9% (3,3 ′, 4,4′-biphenyltetra after ring opening) Purity determined by HPLC analysis of carboxylic acid), acid anhydride rate 99.8%
2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride (hereinafter sometimes abbreviated as a-BPDA): Ube Industries, Ltd., purity 99.6% (after ring opening, 2,3 Purity obtained by HPLC analysis of 3 ′, 4′-biphenyltetracarboxylic acid), acid anhydride rate 99.5% washed with acetone 2,2 ′, 3,3′-biphenyltetracarboxylic acid Dianhydride (hereinafter sometimes abbreviated as i-BPDA): CHANGZHOU WEIJIA CHEMICAL Co., Ltd. Purity 99.9% (HPLC analysis of 2,2 ′, 3,3′-biphenyltetracarboxylic acid after ring opening) The purity obtained in step 1) and acid anhydride ratio 99% washed with NMP are used. Solvent: Wako Pure Chemical Industries, Ltd. Special grade or first grade equivalent 2N sodium hydroxide aqueous solution: Tokyo Kasei Co., Ltd. sodium hydroxide Aqueous solution , 4-diaminocyclohexane (hereinafter, sometimes abbreviated as t-DACH)): used after sublimation purification ZHEJIANG TAIZHOU QINGQUAN MEDICAL & CHEMICAL Co., Ltd. Purity 99.1% a (GC analysis)

In each of the following examples, the evaluation was performed by the following method.

Evaluation of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder
[Solubility of s-BPDA at 25 ° C]
A glass container was charged with 5.0 g of s-BPDA powder having a purity of 99.9% and an acid anhydride ratio of 99.8%, and 50.0 g of a solvent, and sufficiently stirred at 25 ° C. for 3 hours. The undissolved s-BPDA was filtered using Advantech filter paper 5A to obtain a s-BPDA saturated solution. 5 g of s-BPDA saturated solution was placed in an aluminum petri dish and heated at 80 ° C. for 1 hour and 200 ° C. for 1 hour. The mass of s-BPDA contained in the saturated solution was determined from the residue after heating, and the solubility was calculated.
[Light transmittance]
A predetermined amount of s-BPDA powder was dissolved in 2N aqueous sodium hydroxide solution to obtain a 10% by mass solution. Using a MCPD-300 manufactured by Otsuka Electronics Co., Ltd. and a standard cell with an optical path length of 1 cm, a 2N sodium hydroxide aqueous solution was used as a blank, and the light transmittance at 400 nm of the s-BPDA solution was measured.

Evaluation of polyimide precursor and polyimide
[Logarithmic viscosity]
A 0.5 g / dL polyimide precursor N, N-dimethylacetamide solution was measured at 30 ° C. using an Ubbelohde viscometer.
[Light transmittance (polyimide precursor)]
A 10% by mass polyimide precursor / N, N-dimethylacetamide solution was measured with a standard cell having an optical path length of 1 cm using MCPD-300 manufactured by Otsuka Electronics. Using N, N-dimethylacetamide as a blank, the light transmittance at 400 nm of a 10% by mass polyimide precursor / N, N-dimethylacetamide solution was determined.
[Light transmittance (polyimide)]
The light transmittance at 400 nm of a polyimide film having a film thickness of about 10 μm was measured using MCPD-300 manufactured by Otsuka Electronics.
[Elastic modulus, elongation at break]
The polyimide film was punched into an IEC450 standard dumbbell shape as a test piece, and the initial elastic modulus and elongation at break were measured at 30 mm between chucks and a tensile speed of 2 mm / min using TENILON manufactured by ORIENTEC.
[Coefficient of thermal expansion (CTE)]
The polyimide film was cut into a strip shape having a width of 4 mm to obtain a test piece, and the temperature was raised to 300 ° C. at a chuck length of 15 mm, a load of 2 g, and a heating rate of 20 ° C./min using TMA-50 manufactured by Shimadzu Corporation. From the obtained TMA curve, the average coefficient of thermal expansion from 50 ° C. to 200 ° C. was determined.

[Example 1]
10.0 g of unpurified s-BPDA and 10.0 g of N, N-dimethylformamide as a solvent were placed in a glass container, and the mixture was sufficiently stirred at 25 ° C. for 3 hours. The solution was filtered off, and the obtained solid was vacuum-dried at 100 ° C. for 2 hours to obtain s-BPDA powder. The yield was 9.7 g.
The evaluation results of the obtained s-BPDA powder are shown in Table 1.

[Examples 2 to 7]
Except having changed the solvent into the solvent of Table 1, it carried out similarly to Example 1, and obtained s-BPDA powder. The yields were 9.6 g (Example 2), 9.4 g (Example 3), 9.5 g (Example 4), 9.6 g (Example 5), 9.7 g (Example 6), It was 9.6 g (Example 7).
The evaluation results of the obtained s-BPDA powder are shown in Table 1.

Example 8
A glass container was charged with 20.0 g of s-BPDA and 200 g of N-methyl-2-pyrrolidone as a solvent, and sufficiently stirred at 25 ° C. for 3 hours. The solution was filtered, and the obtained solid was vacuum-dried at 100 ° C. for 2 hours to obtain s-BPDA powder. The yield was 15.2g.
5.0 g of this s-BPDA powder is charged into a glass sublimation apparatus, the pressure is reduced to 1 Torr or less, and the temperature of the wall lower surface in contact with the s-BPDA powder is heated to 200 to 220 ° C. to sublimate s-BPDA An s-BPDA crystal powder that was cooled and solidified on the wall surface adjusted to 25 ° C. provided at the top of the sublimation apparatus was obtained. The yield was 3.1 g.
The evaluation results of the obtained s-BPDA powder are shown in Table 1.

[Comparative Example 1]
Table 1 shows the evaluation results of the s-BPDA powder not subjected to treatment such as purification.

[Comparative Examples 2-3]
Except having changed the solvent into the solvent of Table 1, it carried out similarly to Example 1, and obtained s-BPDA powder. The yields were 9.7 g (Comparative Example 2) and 9.7 g (Comparative Example 3).
The evaluation results of the obtained s-BPDA powder are shown in Table 1.

[Comparative Example 4]
5.0 g of s-BPDA powder not subjected to purification or other treatment was charged into a glass sublimation apparatus, and sublimation was performed in the same manner as in Example 8. The yield was 4.4g.
The evaluation results of the obtained s-BPDA powder are shown in Table 1.

[Comparative Example 5]
A glass container was charged with 5.0 g of s-BPDA powder and 200 g of acetic anhydride, heated to reflux, and stirred for 3 hours to dissolve. At this time, the solution was colored yellow. It cooled to 25 degreeC and precipitated. The solution was filtered off, and the obtained solid was vacuum-dried at 100 ° C. for 2 hours to obtain s-BPDA powder. The yield was 4.2g.
The evaluation results of the obtained s-BPDA powder are shown in Table 1.

  As can be seen from the results shown in Table 1, the s-BPDA with reduced colorability according to the present invention is capable of transmitting light having a wavelength of 400 nm with respect to a solution obtained by dissolving 10% by mass in a 2N aqueous sodium hydroxide solution. The rate is over 75%, preferably 80% or more.

  In the following, the tetracarboxylic acid component is composed of s-BPDA separated and recovered by the purification method of the present invention, and the diamine component is an aliphatic diamine, a diamine having an alicyclic structure, a halogen group, a carbonyl group, Examples of polyimides selected from the group consisting of aromatic diamines having any substituent of a sulfonyl group will be described with reference to examples.

Example 9
1.40 g (0.0122 mol) of trans-1,4-diaminocyclohexane (t-DACH) was put in a reaction vessel, and dissolved in 28.4 g of N, N-dimethylacetamide dehydrated using a molecular sieve. This solution was heated to 50 ° C., and 3.50 g (0.0119 mol) of s-BPDA powder obtained in Example 3 and 0.09 g (0.0003 mol) of a-BPDA powder were gradually added. . The mixture was stirred at 50 ° C. for 6 hours to obtain a uniform and viscous polyimide precursor solution.
The obtained polyimide precursor solution was applied to a glass substrate and heated under a nitrogen atmosphere at 120 ° C. for 1 hour, 150 ° C. for 30 minutes, 200 ° C. for 30 minutes, raised to 350 ° C. and heated for 5 minutes. Was imidized to obtain a colorless and transparent polyimide / glass laminate. Next, the obtained polyimide / glass laminate was immersed in water and then peeled to obtain a polyimide film having a thickness of 10 μm.
Table 2 shows the results of measuring the characteristics of the film.

Example 10
Except having used the acid component described in Table 2, it carried out similarly to Example 9, and obtained the polyimide precursor solution and the polyimide film.
Table 2 shows the results of measuring the characteristics of the film.

[Comparative Example 6]
A polyimide precursor solution and a polyimide film were obtained in the same manner as in Example 9 except that the s-BPDA powder that was not purified in Comparative Example 1 was used as the tetracarboxylic acid component.
Table 2 shows the results of measuring the characteristics of the film.

  As is apparent from Table 2, by using s-BPDA separated and recovered by the purification method of the present invention, Tokai made polyimide is improved, and the light transmittance at 400 nm when a film having a film thickness of 10 μm is obtained. It can be 80% or more.

  According to the present invention, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder with little coloration can be easily obtained by a method by simple operation under mild conditions without requiring large-scale equipment. Possible purification methods can be provided. Further, the 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder with little coloration obtained by the purification method of the present invention is used for a high-performance optical material having good transparency, particularly flexible. A polyimide that can be suitably used for a transparent substrate in a display device such as a display or a touch panel can be provided.

Claims (7)

  A solvent having a solubility at 25 ° C. in 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride of 0.1 g / 100 g or more, and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride The powder is mixed in an inhomogeneous state in which at least a portion of the 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder is not dissolved, and then undissolved 3,3 ′ from the mixture. A method for purifying 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride dianhydride powder, which comprises separating and recovering 4,4′-biphenyltetracarboxylic dianhydride powder.   The 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride has a solubility at 25 ° C. of 1 g / 100 g or more in the solvent of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. A method for purifying 4'-biphenyltetracarboxylic dianhydride powder.   The 3,3 'according to claim 1 or 2, wherein the solvent is N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone. , 4,4′-biphenyltetracarboxylic dianhydride powder purification method.   Light transmittance of a wavelength of 400 nm and an optical path length of 1 cm with respect to a solution obtained by dissolving the separated and recovered 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder in a 2N aqueous sodium hydroxide solution at a concentration of 10% by mass. The method for purifying 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride powder according to any one of claims 1 to 3, wherein the ratio is 75% or more.   The 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder separated and recovered is further sublimated, and 3,3 ′, 4,4 according to any one of claims 1 to 4 Purification method of '-biphenyltetracarboxylic dianhydride powder. A method for producing 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder using the purification method according to claim 1 .   A tetracarboxylic acid component comprising the 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride powder separated and recovered by the purification method according to claim 1, an aliphatic diamine, Polymerization imidization of diamines having an alicyclic structure and diamine components composed of diamines selected from the group consisting of aromatic diamines having a substituent of any one of a halogen group, a carbonyl group and a sulfonyl group A method for producing polyimide, comprising: