JP4829913B2 - Polyimide and method for producing the same - Google Patents

Description

  The present invention relates to a polyimide having a novel repeating structural unit and a method for producing the polyimide. The polyimide according to the present invention can be suitably used for films and substrates in the field of optical materials, protective films and insulating films in the field of electronic materials, flexible printed circuit boards, and the like.

  Aromatic polyimides are widely used in aerospace materials, heat resistant materials, electronic materials, and the like because they are excellent in heat resistance, dimensional stability, mechanical strength, insulation, and the like.

  Further, it is known that a polyimide having excellent transparency can be obtained by substituting part or all of the aromatic ring of an aromatic polyimide with an aliphatic hydrocarbon or an alicyclic hydrocarbon. This polyimide is used in fields such as a liquid crystal alignment film, and has also been used as a heat resistant transparent substrate.

  Moreover, as a polyimide in which the aromatic ring of the aromatic polyimide is substituted with an alicyclic hydrocarbon, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (hereinafter sometimes abbreviated as CBDA), A polyimide obtained by a reaction with an aromatic diamine or an aliphatic diamine is known.

  As an example of such a polyimide, the following Non-Patent Document 1 discloses a polyimide obtained by a reaction of, for example, CBDA and 2,2′-bis (trifluoromethyl) benzidine (hereinafter abbreviated as TFMB). Has been. Non-Patent Document 1 describes that this polyimide has a low coefficient of linear expansion, a high glass transition temperature, and a low dielectric constant.

  However, the TFMB used in Non-Patent Document 1 is very expensive because a trifluoromethyl group is introduced. Therefore, when the TFMB is used, the cost has to be high.

  Patent Document 1 below discloses a polyimide precursor and a polyimide obtained by a reaction between a substituted or unsubstituted cyclobutanetetracarboxylic acid and various diamine compounds in a linear or trans configuration. Patent Document 1 describes that the polyimide precursor and the polyimide have a low dielectric constant, a low linear thermal expansion coefficient, a high transparency, and a high glass transition temperature.

  However, when a linear diamine compound other than the TFMB is used, there is a problem that the imidized compound becomes very brittle after imidization by heating.

  On the other hand, the following Patent Document 2 discloses a polyimide obtained by a reaction between an aromatic tetracarboxylic dianhydride and a specific ester type diamine. This polyimide is excellent in heat resistance and has a low linear expansion coefficient.

Here, if the CBDA described in Non-Patent Document 1 and the ester-type diamine described in Patent Document 2 are used in combination, polyimide can be obtained relatively inexpensively. However, Non-Patent Document 1 and Patent Document 2 do not describe any combination of these. About the polyimide obtained by this combination, the following patent document 3 is suggested as an example of a polyimide. However, although Patent Document 3 describes that the polyimide obtained by this combination has excellent heat resistance, thermoplasticity, adhesiveness and workability, other properties such as transparency and linearity are described. There is no description about the expansion coefficient.
JP 2005-336244 A JP-A-8-48773 Japanese Patent Laid-Open No. 7-3019 High Performance Polymer, 13, S93-S106, 2001

  The objective of this invention is providing the polyimide which is excellent in transparency and heat resistance in view of the present condition of the prior art mentioned above, and the manufacturing method of this polyimide.

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. According to the present invention, a polyimide having a structure represented by the following formula (1) as a main repeating structural unit is provided.

  Moreover, the manufacturing method of the polyimide which concerns on this invention is a manufacturing method of the polyimide of this invention, Comprising: 1,2,3,4-cyclobutane tetracarboxylic dianhydride and 1,4-bis (4-aminobenzoyl) After obtaining a polyamic acid by reacting with (oxy) benzene, the polyamic acid is imidized to obtain a polyimide having a structure represented by the formula (1) as a main repeating structural unit. .

  Details of the present invention will be described below.

  The polyimide which concerns on this invention makes the structure shown by following formula (1) the main repeating structural unit.

  The polyimide according to the present invention is obtained by reacting 1,2,3,4-cyclobutanetetracarboxylic dianhydride with 1,4-bis (4-aminobenzoyloxy) benzene to obtain a polyamic acid, It can be obtained by imidizing the polyamic acid. The polyimide thus obtained is excellent in transparency and heat resistance. The polyimide according to the present invention is almost colorless and transparent. Further, the polyimide according to the present invention may have a low linear expansion coefficient.

(1,2,3,4-cyclobutanetetracarboxylic dianhydride)
The 1,2,3,4-cyclobutanetetracarboxylic dianhydride (hereinafter sometimes abbreviated as CBDA) is an alicyclic tetracarboxylic dianhydride. As the CBDA, cis, trans, cis-1,2,3,4-cyclobutanetetracarboxylic acid-1,2: 3,4-dianhydride is preferable.

  The CBDA can be synthesized by a known method. For example, it can be synthesized in one step by photocyclization (dimerization) reaction of maleic anhydride. Such synthetic methods are described in, for example, JP-A-59-212495, JP-A-2003-192585, JP-A-2006-328027, and Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 38, 108-116, 2001, and the like.

  By using the CBDA, a polyimide having excellent heat resistance, dimensional stability, and transparency can be obtained. Furthermore, since the raw material used for synthesizing the CBDA is inexpensive and the synthesis of CBDA is easy, CBDA can be easily obtained.

  In addition to the CBDA, other conventionally known tetracarboxylic dianhydrides can be used as long as they do not depart from the object of the present invention.

  Specific examples of the other tetracarboxylic acid anhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3′4,4′- Aromatic tetracarboxylic dianhydrides such as benzophenone tetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride or 3,3′4,4′-diphenylsulfone tetracarboxylic dianhydride; 3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2 .2] Oct-7-ene-2,3: 5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3: 5,6-tetracarboxylic dianhydride or 1 -Carboxymethyl 2,3,5-cyclopentane tricarboxylic acid-2,6: 3,5-aliphatic, such as dianhydrides or alicyclic tetracarboxylic dianhydride, and the like.

(1,4-bis (4-aminobenzoyloxy) benzene)
1,4-bis (4-aminobenzoyloxy) benzene (hereinafter sometimes abbreviated as BABB) is a diamine compound. This can be obtained by synthesizing a dinitro compound having an ester group by a condensation reaction of p-nitrobenzoyl halide and hydroquinone, and then reducing the nitro group by a reduction reaction.

  Various p-nitrobenzoyl halides used in the condensation reaction can be used, but p-nitrobenzoyl chloride is preferred because the cost can be reduced. A catalyst is preferably used in the condensation reaction.

  As the catalyst used in the condensation reaction, organic amines such as triethylamine or pyridine, or alkali metal hydroxides such as sodium hydroxide or potassium hydroxide are preferably used.

  The solvent used in the condensation reaction is not particularly limited as long as it is inert during the condensation reaction. For example, ethers such as tetrahydrofuran, dioxane or ethylene glycol dimethyl ether, and aromatics such as toluene or xylene. Aromatic hydrocarbons or esters such as ethyl acetate or butyl acetate can be used. Moreover, these solvents may be used independently and may use 2 or more types together. Of these, ethers such as tetrahydrofuran, dioxane or ethylene glycol dimethyl ether are preferred.

  Although the usage-amount of the said solvent should just be sufficient quantity to dissolve a raw material, it is not specifically limited, Usually, it is about 50-1000 weight part with respect to a total of 100 weight part of a raw material. The reaction temperature is usually about 0 to 100 ° C, preferably about 0 to 50 ° C. The reaction time is about 1 to 24 hours.

  After the condensation reaction is completed, the product 1,4-bis (4-nitrobenzoyloxy) benzene has a low solubility and is often precipitated together with the catalyst hydrochloride. In this case, the catalyst hydrochloride may be removed by dissolving it in water or a lower alcohol such as methanol or ethanol, and 1,4-bis (4-nitrobenzoyloxy) benzene may be filtered off.

  As a method of reducing the nitro group of 1,4-bis (4-nitrobenzoyloxy) benzene after the condensation reaction, a conventionally known reduction method can be used. As the reduction method, the catalytic reduction method is preferred because of its high yield and easy reaction.

  Examples of the catalyst used in the reduction reaction include nickel, ruthenium, palladium, platinum, and rhodium. Among these, palladium is preferable because it is easily available and the cost can be reduced. These catalysts are preferably used by being supported on the surface of a carrier such as carbon (activated carbon), alumina or silica gel.

  The amount of the catalyst used in the reduction reaction is not particularly limited, but is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the total raw material.

  The solvent used in the above reduction reaction is not particularly limited as long as it is inert during the reduction reaction. However, 1,4-bis (4-nitrobenzoyloxy) benzene, which is a dinitro form, is sufficient. A solvent that can be dissolved in is preferable. Examples of such solvents include ethers such as dioxane, tetrahydrofuran or ethylene glycol dimethyl ether, ketones such as acetone or methyl ethyl ketone, esters such as ethyl acetate or butyl acetate, or N, N-dimethylformamide or N, N -Amides such as dimethylacetamide can be used. These solvents may be used alone or in combination of two or more. Among them, amides such as N, N-dimethylformamide or N, N-dimethylacetamide are preferable because of excellent solubility of the raw materials.

  The amount of the solvent used in the reduction reaction is not particularly limited as long as it is sufficient to dissolve 1,4-bis (4-nitrobenzoyloxy) benzene. The amount is about 50 to 1000 parts by weight with respect to 100 parts by weight of 1,4-bis (4-nitrobenzoyloxy) benzene. Although reaction temperature is not specifically limited, Usually, it is about 20-150 degreeC, Preferably it is about 20-100 degreeC.

  The above reduction reaction is usually performed while dissolving a raw material in a solvent, adding a catalyst, introducing hydrogen gas, and stirring at a predetermined temperature. The pressure in this reaction is usually about 1 MPa from normal pressure to gauge pressure. The reduction reaction is continued until hydrogen absorption stops. After the reduction reaction is completed, the catalyst is removed by filtration, and crystals are precipitated by concentrating or cooling the mother liquor. The crystals are taken out by filtration, washed and dried to obtain the target BABB. If necessary, it may be further purified by recrystallization using an appropriate solvent.

  In addition to the above-mentioned BABB, other conventionally known diamine compounds can be used as long as they do not depart from the object of the present invention.

Specific examples of the other diamine compounds include p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 4,4′-diaminobiphenyl, and 3,3′-dimethyl-4,4. '-Diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 4,4 '-Diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, 1,4-bis (4-aminophenoxy) benzene 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) ) Benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis Aromatic diamine compounds such as [4- (4-aminophenoxy) phenyl] propane or 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, or 1,4-diaminocyclohexane, 4, 4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, 3 (4), 8 (9),-bis (aminomethyl) tricyclo [5,2,1,0 ^{2, 6]} decane, or 2,5 (6) - bis (aminomethyl) bicyclo [2,2,1] alicyclic diamine compounds such heptane or the like It is below.

(Production method of polyimide)
As a method for producing the polyimide according to the present invention, a method in which the CBDA and the BABB are reacted to obtain a polyamic acid and then the polyamic acid is imidized is preferable.

  In the synthesis of the polyamic acid, the CBDA and the BABB are reacted in a solvent. Thereby, a polyamic acid-containing solution can be obtained.

  The CBDA and the BABB are preferably reacted in a polar solvent, and are preferably reacted in a polar organic solvent. The solvent is preferably sufficiently dehydrated.

  As a method for synthesizing the polyamic acid, preferably, approximately equimolar amounts of the CBDA and the BABB are dissolved in a sufficiently dehydrated solvent such as an organic polar solvent in an inert gas atmosphere. At this time, almost no change such as heat generation is observed. This seems to be due to the weak basicity of the amino group of BABB. Next, the reaction is carried out at room temperature to about 70 ° C. for about 1 to 48 hours. The reaction rate at this time varies depending on the solvent used. Since the basicity of the amino group of BABB is weak, the reaction is preferably carried out under heating.

  The solvent used for the reaction of the CBDA and the BABB can be a conventionally known solvent and is not particularly limited. For example, N, N-dimethylformamide, N, N-dimethylacetamide or N-methyl- Amido solvents such as 2-pyrrolidone, lactones such as γ-butyrolactone, γ-valerolactone or δ-valerolactone, carbonates such as ethylene carbonate or propylene carbonate, glymes such as monoglyme, diglyme, triglyme or tetraglyme, Alternatively, an aprotic polar solvent such as dimethyl sulfoxide can be used. Moreover, you may use the solvent which added hydrocarbon solvents, such as toluene or xylene, or ether solvents, such as THF or dioxane, to these. The amount of the solvent used may be such that the concentration of the obtained polyamic acid is preferably about 5 to 50% by weight, more preferably about 10 to 30% by weight.

  The polyamic acid obtained as described above or the polyamic acid-containing solution is used to imidize the polyamic acid to obtain a polyimide having the structure represented by the above formula (1) as a main repeating structural unit. be able to.

  In imidizing the polyamic acid, it is preferable to use either a thermal method or a chemical method. Moreover, when imidating the said polyamic acid, it is more preferable to use the thermal imidation method which carries out dehydration ring closure thermally, the chemical imidation method using a dehydrating agent, etc.

  As the thermal imidization method, for example, a polyamic acid-containing solution is applied onto a substrate such as a PET film, a glass plate, or a metal support to form a film, and then at about 40 to 150 ° C. for 10 minutes to 2 hours. After drying to a certain extent, it is peeled off to obtain a polyamic acid in a film state. The polyamic acid film is preferably heated with the end portion fixed to the support, and finally heat-treated at about 250 to 400 ° C. for about 10 minutes to 3 hours. A polyimide can be obtained.

  As the chemical imidization method, for example, a dehydrating agent such as acetic anhydride and a catalyst such as triethylamine, pyridine, picoline, or quinoline are added to the polyamic acid solution, and then the same operation as the thermal imidization method is performed. Thus, the polyimide according to the present invention can be obtained in a film state.

  In addition, various additives, inorganic fillers, and the like can be added to the polyimide according to the present invention so long as the object of the present invention is not impaired.

  When the polyimide of the present invention is used in a film state, it depends on the use, but the thickness of the film is preferably 5 to 200 μm, more preferably 10 to 100 μm.

  Since the polyimide which concerns on this invention makes the structure shown by said Formula (1) the main repeating structural unit, it is excellent in transparency and heat resistance. Therefore, the polyimide according to the present invention can be suitably used for films and substrates in the field of optical materials, protective films and insulating films in the field of electronic materials, flexible printed circuit boards, and the like.

Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention. In addition, this invention is not limited to a following example.
[FT-IR measurement]
Measurement was performed using “NICOLET 380” manufactured by ThermoElectron as a spectrometer.
^[1 H-NMR measurement]
Measurement was performed at 23 ° C. in DMSO-d ₆ using a JEOL NMR measurement apparatus “ECX-400”.
[DSC measurement]
Using “DSC-60” manufactured by Shimadzu Corporation, the measurement was performed under an argon atmosphere at a heating rate of 10 ° C./min.
[Pyrolysis characteristics evaluation]
Using a “DTG-60” manufactured by Shimadzu Corporation, the temperature was measured at a heating rate of 10 ° C./min in an argon atmosphere, and a 5% weight loss temperature was evaluated.
[Measurement of thermal expansion coefficient]
Using “TMA / SS6100” manufactured by SII Nanotechnology, the temperature was measured at a rate of temperature increase of 15 ° C./min in a nitrogen atmosphere, and the average value of the coefficient of thermal expansion from 100 ° C. to 200 ° C. was obtained.
[Evaluation of transparency]
Using a UV-visible spectrophotometer “UVmini 1240” manufactured by Shimadzu Corporation, the transmittance of light in the wavelength range of 1100 nm to 200 nm was measured.

(Synthesis Example 1)
In a nitrogen-substituted reaction vessel, using 2300 ml of THF as a solvent and 133.4 g (1.32 mol) of triethylamine as a catalyst, 66.0 g (0.60 mol) of hydroquinone and 233.6 g of p-nitrobenzoyl chloride ( 1.26 mol) was reacted for 2 hours. During the reaction, the solution temperature, which was initially cooled to 6 ° C., rose to 24 ° C. at the end of the reaction.

  The precipitated reaction product and triethylamine hydrochloride were removed by filtration, washed with water and methanol, and then the triethylamine hydrochloride was removed and dried to obtain 1,4-bis (4-nitrobenzoyl) which is a dinitro compound. Oxy) benzene was obtained. The yield was 93.5%.

119.7 g of the obtained 1,4-bis (4-nitrobenzoyloxy) benzene was dissolved in 700 ml of DMF in a reaction vessel, and 3.0 g of 5% Pd / C (50% wet) was added. H-- ₂ gas was supplied here, the internal pressure was set to 0.4 MPa, and a reduction reaction was performed at about 60 ° C. for 7 hours. After removing the catalyst and the solvent, it was recrystallized and dried under reduced pressure to obtain 1,4-bis (4-aminobenzoyloxy) benzene as the target compound. The yield was 90.8%.

It was 320 degreeC when melting | fusing point was measured by DSC method. This crystal was subjected to ¹ H-NMR measurement and FT-IR measurement, and it was confirmed that 1,4-bis (4-aminobenzoyloxy) benzene, which was the object, was obtained.

(Synthesis Example 2)
The inside irradiation type glass container is purged with nitrogen, 250 g of ethyl acetate and 25.5 g of maleic anhydride are mixed in the glass container, irradiated with light with a high pressure mercury lamp under cooling, and reacted at about 20 ° C. for 6 hours. It was. After completion of the reaction, the precipitated product was collected by filtration, washed with ethyl acetate, and then dried under reduced pressure to obtain the target compound 1,2,3,4-cyclobutanetetracarboxylic dianhydride. . The yield was 7.8%.

The obtained 1,2,3,4-cyclobutanetetracarboxylic dianhydride crystals were subjected to ¹ H-NMR measurement and FT-IR measurement, and the target 1,2,3,4-cyclobutanetetra It was confirmed that carboxylic dianhydride was obtained.

Example 1
In a glass container purged with nitrogen, 8 ml of N, N-dimethylacetamide, 0.888 g (2.55 mmol) of 1,4-bis (4-aminobenzoyloxy) benzene, and 1,2,3,4-cyclobutanetetracarboxylic 0.500 g (2.55 mmol) of acid dianhydride was mixed. At this time, no change such as exotherm was observed. This was stirred for 20 hours on a hot stirrer at 70 ° C. to obtain a uniform and transparent slightly yellow viscous liquid.

  This solution was applied onto a PET film using an applicator, dried at 60 ° C. for 30 minutes, and further dried at 100 ° C. for 30 minutes to obtain a polyamic acid (polyamic acid film) in a film state. This polyamic acid film was peeled from the PET film. Thereafter, the polyamic acid film was kept at 100 ° C. for 1 hour in a nitrogen atmosphere, further kept at 200 ° C. for 1 hour, and further kept at 300 ° C. for 1 hour to perform imidization. In this way, a film-like polyimide (polyimide film) corresponding to the polyimide having the structure represented by the above formula (1) as the main repeating structural unit was obtained. The obtained polyimide film had a thickness of 11 μm and was almost colorless and transparent, but was slightly brittle. The FT-IR spectrum of the obtained polyimide film is shown in FIG.

  When the thermal decomposition characteristics of this polyimide film were evaluated, the 5% weight loss temperature showed a good value of 456 ° C. When the transparency was evaluated, the average value of the transmittance of visible light from 380 nm to 780 nm was 84.5%, the transmittance at 400 nm was 77%, and the absorption edge wavelength was 321 nm.

(Example 2)
In Example 1, except that the solvent was changed to N-methyl-2-pyrrolidone, a film state corresponding to polyimide having the structure represented by the above formula (1) as a main repeating structural unit in the same manner as in Example 1. Of polyimide (polyimide film) was prepared. The obtained polyimide film had a thickness of 15 μm, was almost colorless and transparent, and was flexible.

  The coefficient of thermal expansion of this polyimide film was measured and showed a low value of 25 ppm. Moreover, the polyimide film had a glass transition temperature of 304 ° C. determined from the inflection point of the thermal expansion coefficient curve, and had high heat resistance.

  When the thermal decomposition characteristics of this polyimide film were evaluated, the 5% weight loss temperature showed a good value of 474 ° C.

The FT-IR spectrum of the polyimide obtained in Example 1.

Claims (2)

A polyimide having a structure represented by the following formula (1) as a main repeating structural unit.

It is a manufacturing method of the polyimide according to claim 1, Comprising:
After obtaining a polyamic acid by reacting 1,2,3,4-cyclobutanetetracarboxylic dianhydride with 1,4-bis (4-aminobenzoyloxy) benzene, the polyamic acid is imidized. By this, the polyimide which makes the structure shown by said Formula (1) the main repeating structural unit is obtained, The manufacturing method of a polyimide characterized by the above-mentioned.

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