JP4829925B2 - Polyimide and method for producing the same - Google Patents

Description

  The present invention relates to a polyimide and a method for producing the same.

Aromatic polyimides are widely used in aerospace materials, heat-resistant materials, electronic materials and the like because they have excellent characteristics in heat resistance, dimensional stability, mechanical strength, insulation, and the like.
Further, semi-aromatic polyimides in which part or all of the aromatic structure of the aromatic polyimide is replaced with an aliphatic structure or an alicyclic hydrocarbon structure are known.

As the semiaromatic polyimide, a semiaromatic obtained from 1,2,3,4-cyclobutanetetracarboxylic dianhydride (hereinafter sometimes abbreviated as CBDA) and an aromatic diamine or an aliphatic diamine. Examples thereof include polyimide.
For example, Patent Document 1 discloses that polyimide precursors and polyimides of substituted and unsubstituted cyclobutanetetracarboxylic acid and various diamine compounds in a linear or trans configuration have a low dielectric constant and a low linear thermal expansion coefficient (hereinafter referred to as linear expansion). (Which may be abbreviated as “rate”), high transparency, and high glass transition temperature.
Non-Patent Document 1 discloses that a polyimide of CBDA and 2,2′-bis (trifluoromethyl) benzidine (hereinafter sometimes abbreviated as TFMB) has a low coefficient of linear expansion, a high glass transition temperature, and a low dielectric constant. It is disclosed to have a rate.

Patent Document 2 discloses that a polyimide obtained from a specific ester-type diamine and an aromatic tetracarboxylic dianhydride has a very low linear expansion coefficient.
Patent Document 3 suggests that the same combination of polyimides as Patent Document 2 may have excellent thermoplasticity and adhesiveness.

  Patent Document 4 discloses that the polyimide represented by the formula (II) is excellent in heat resistance and transparency.

JP 2005-336244 A JP-A-8-48773 Japanese Patent Laid-Open No. 7-3019 Japanese Examined Patent Publication No. 2-11615 High Performance Polymer, 13, S93-S106, 2001

Although the polyimide disclosed in Non-Patent Document 1 has excellent characteristics, TFMB having a trifluoromethyl group is very expensive and is extremely disadvantageous in terms of industrial production. In addition, as disclosed in Patent Document 1 and Non-Patent Document 1, when synthesizing a polyimide from CBDA capable of maintaining relatively linearity and a linear diamine, the present inventors have examined the above TFMB. It was found that other linear diamines had the problem of becoming very brittle after imidization by heating.
Furthermore, when the present inventors examined the polyimide disclosed in Patent Document 3, the film is stable and flexible because it tends to be brittle depending on the solvent used in the imidation reaction or the heat treatment conditions during imidization. It was found that there is a problem that it is difficult to obtain.

  In view of the above circumstances, the problem to be solved by the present invention is to provide a novel polyimide that is colorless and transparent, has excellent heat resistance and low linear expansion coefficient, and is excellent in toughness, and a method for producing the same. .

  As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention.

The present invention is as follows.
[1]
Polyimide containing structural units represented by the following formulas (I) and (II).
Formula (I)
[In the formula (I), R represents H or CH ₃ . ]
Formula (II)
[2]
The polyimide according to the above [1], wherein the proportion of the structural units represented by the formulas (I) and (II) is 85:15 to 25:75 in terms of molar ratio.
[3]
The polyimide according to [1] or [2], wherein the ratio of the structural units represented by the formulas (I) and (II) is 80:20 to 30:70 in terms of molar ratio.
[4]
The method for producing a polyimide according to any one of [1] to [3],
1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,4-bis (4-aminobenzoyloxy) benzene and / or 2,5-bis (4-aminobenzoyloxy) toluene, Reacting 4-bis (4-aminophenoxy) benzene with polyamic acid;
The manufacturing method of a polyimide including the process of imidating the said polyamic acid.
[5]
Polyamic acid containing structural units represented by the following formulas (III) and (IV).
Formula (III)
[In the formula (III), R represents H or CH ₃ . ]
Formula (IV)

  According to the present invention, it is possible to provide a novel polyimide that is colorless and transparent, has excellent heat resistance and low linear expansion coefficient, and is excellent in toughness, and a method for producing the same.

  Hereinafter, the best mode for carrying out the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

The polyimide of this invention is a polyimide containing the structural unit shown by following formula (I) and (II).
Formula (I)
[In the formula (I), R represents H or CH ₃ . ]
Formula (II)
The polyimide of the present invention is a novel polyimide that is colorless and transparent, has excellent heat resistance and low linear expansion coefficient, and is excellent in toughness.

In the present invention, the ratio of the structural units represented by the formulas (I) and (II) is preferably 90:10 to 25:75, more preferably 85:15 to 25:75, in terms of molar ratio. Preferably, it is 80: 20-30: 70.
When the proportion of the structural units represented by the formulas (I) and (II) is within the above range, a polyimide having lower linear expansion coefficient and strong toughness as characteristics can be obtained.

The polyimide of the present invention is preferably a polyimide produced by the following production method. As a method for producing polyimide in the present invention, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and 1,4-bis (4-aminobenzoyloxy) benzene (hereinafter, BABB) and / or 2,5-bis (4-aminobenzoyloxy) toluene (hereinafter sometimes abbreviated as BABT) and 1,4-bis (4-aminophenoxy) benzene (hereinafter referred to as BABT). , BAPB) may be reacted to obtain a polyamic acid solution, and then the polyamic acid may be thermally or chemically imidized.
In addition to BABB and / or BABT and BAPB, if necessary, other tetracarboxylic dianhydrides other than CBDA and other conventionally known diamine compounds other than BABB and / or BABT and BAPB may be reacted with CBDA. The polyimide of this invention can also be manufactured by the method to make it.

As 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) used in the present invention, from the viewpoint of heat resistance and low linear expansion characteristics, cis, trans, cis-1, 2, 3, 4 -Cyclobutanetetracarboxylic acid-1,2: 3,4-dianhydride can be preferably used. The method for synthesizing CBDA is not particularly limited as long as it is a method known by the business operator, and examples thereof include a method of synthesizing in one step by a photocyclization (dimerization) reaction of maleic anhydride.
As a synthesis method of CBDA, for example, Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 38, 108-116, 2001, JP 59-212495 A, JP 2003-192585 A, and JP 2006. A method disclosed in Japanese Patent No. 328027 is known. All CBDAs obtained by these synthesis methods are cis, trans, cis bodies. Hereinafter, in the present invention, CBDA refers to this cis, trans, cis body.
Since raw materials for CBDA synthesis can be easily obtained at low cost, and since synthesis is easy, it is very useful to use CBDA as a raw material. In addition, a polyimide obtained using CBDA as a starting material is excellent in heat resistance, dimensional stability, and transparency.

  If it is a range which does not deviate from the objective of this invention, other conventionally well-known tetracarboxylic dianhydrides other than CBDA can be used. For example, as the tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3′4,4′-benzophenonetetracarboxylic dianhydride Aromatic tetracarboxylic dianhydrides such as anhydrides, 4,4′-oxydiphthalic anhydride, and 3,3′4,4′-diphenylsulfone tetracarboxylic dianhydride, and 1,2,3,4 -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, and 1-carboxy Mechi 2,3,5-cyclopentane tricarboxylic acid-2,6: 3,5-aliphatic anhydrides or alicyclic tetracarboxylic dianhydride, and the like.

1,4-bis (4-aminobenzoyloxy) benzene (BABB), 2,5-bis (4-aminobenzoyloxy) toluene (BABT) and 1,4-bis (4-aminophenoxy) used in the present invention ) The method for synthesizing benzene (BAPB) is not particularly limited as long as it is a method known by the operator.
BABB or BABT can be obtained by, for example, synthesizing a dinitro compound having an ester group by a condensation reaction of p-nitrobenzoyl halide and hydroquinone or 2-methylhydroquinone, and then reducing the nitro group.
BAPB can be obtained, for example, by synthesizing a dinitro compound having an ether group by a condensation reaction of p-chloronitrobenzene and hydroquinone and then reducing the nitro group. BAPB is sold under the product name “TPE-Q” by Wakayama Seika Kogyo.

  About the ratio of BABB and / or BABT and BAPB to be used, it is preferable that a molar ratio is BABB and / or BABT: BAPB = 90: 10-25: 75 from a viewpoint of a low linear expansion coefficient and toughness, and 85: It is more preferably 15 to 25:75, and further preferably 80:20 to 30:70. It is preferable that the ratio of BABB and / or BABT is within the above range because a polyimide having sufficient toughness can be obtained stably. Further, it is preferable that BAPB is in the above range because a polyimide having a desired low linear expansion coefficient (for example, 50 ppm / ° C., preferably 40 ppm / ° C.) can be obtained. Moreover, either BABB and BABT may be used independently and may be used together.

Any other conventionally known diamine compounds other than BABB and / or BABT and BAPB can be used as long as they do not depart from the object of the present invention. For example, as the other diamine compound, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 4,4′-diaminobiphenyl, 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, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-Aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphe Bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, and 2 , 2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane and the like, and 1,4-diaminocyclohexane, 4,4′-diaminodicyclohexylmethane, 4,4′-diamino-3 , 3'-dimethyl dicyclohexyl methane, 3 (4), 8 (9), - bis (aminomethyl) tricyclo [5,2,1,0 ^2,6] decane, and 2,5 (6) - bis (amino And alicyclic diamine compounds such as methyl) bicyclo [2,2,1] heptane.

  As a method for synthesizing polyimide in the present invention, CBDA and BABB and / or BABT and BAPB are reacted in a polar organic solvent to obtain a polyamic acid solution, and then the polyamic acid is thermally or chemically imidized. The method can be suitably used.

  As a method for synthesizing the polyamic acid, the following method can be suitably used. 1) Pre-dissolve BABB and / or BABT and BAPB in a fully dehydrated polar organic solvent, preferably under an inert gas atmosphere, and then approximately equimolar CBDA with the sum of BABB and / or BABT and BAPB And a method of reacting at a temperature of about 0 ° C. to 70 ° C. for about 1 to 48 hours, 2) dissolving BABB and / or BABT and CBDA while reacting, then adding BAPB and adding 1) Examples include a method of reacting under the same conditions, 3) a method of dissolving BAPB and CBDA while reacting, and then adding BABB and / or BABT and reacting under the same conditions as in 1).

  As said polar organic solvent, a conventionally well-known solvent can be used in a polyimide synthesis | combination. For example, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, and N-methyl-2-pyrrolidone, lactones such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone, ethylene carbonate And carbonates such as propylene carbonate, glymes such as monoglyme, diglyme, triglyme, and tetraglyme, and aprotic polar solvents such as dimethyl sulfoxide. These solvents may be used alone or as a mixed solvent. In addition, a mixed solvent can be used by adding a hydrocarbon solvent such as toluene and xylene, an ether solvent such as THF and dioxane, or the like to these solvents. It is preferable to use the solvent so that the concentration of the resulting polyamic acid solution is preferably 5% to 50% by mass, more preferably about 10 to 30% by mass.

  In order to obtain a polyimide containing the structural units represented by the above formulas (I) and (II) from the polyamic acid solution obtained as described above, a thermal imidization method in which thermal dehydration and ring closure is performed, a dehydrating agent is used. Any method of the chemical imidization method to be used may be used.

  As the thermal imidization method, for example, a polyamic acid solution is applied onto a substrate such as a PET film, a glass plate, or a metal support to form a film, and then dried at about 40 to 150 ° C. for about 10 minutes to 2 hours. Then, this is peeled off to obtain a polyamic acid film. This film is preferably heated in an inert gas atmosphere with the end fixed to the support, and finally heat-treated at about 250 to 400 ° C. for about 10 minutes to 3 hours. A polyimide film containing the structural units represented by the formulas (I) and (II) can be obtained.

  As the chemical imidization method, for example, after adding a dehydrating agent such as acetic anhydride and a catalyst such as triethylamine, pyridine, picoline, and quinoline to the polyamic acid solution, a polyimide is obtained by performing the same operation as the thermal imidization method. Film can be obtained.

As long as it does not deviate from the object of the present invention, various additives such as an antioxidant, a light stabilizer, and an end-capping agent can be blended or combined with an inorganic filler or the like.
For example, a film containing an additive or the like can be obtained by blending the above-mentioned additive or inorganic filler into a polyamic acid solution to form a polyamic acid film and then imidizing it.

  When the polyimide of the present invention is used as a film, depending on the use, the thickness of the film is preferably about 5 μm to 200 μm, more preferably about 10 μm to 100 μm.

The polyamic acid of the present invention is a polyamic acid containing structural units represented by the following formulas (III) and (IV).
Formula (III)
[In the formula (III), R represents H or CH ₃ . ]
Formula (IV)

The polyamic acid of the present invention is preferably a polyamic acid produced by the above polyimide production method.
In the present invention, the polyimide of the present invention can be obtained by ring-closing the solution containing these polyamic acids by a thermal imidization method, a chemical imide method or the like.

  In the present invention, the proportion of the structural units represented by the formulas (III) and (IV) is preferably 90:10 to 25:75, more preferably 85:15 to 25:75, in terms of molar ratio. Preferably, it is 80: 20-30: 70.

  Examples are shown below, but the present invention is not limited thereto. The measurement methods in the examples are as follows.

[FT-IR measurement]
The measurement was performed by the ATR method using “NICOLET 380” manufactured by ThermoElectron as a spectrometer.

[Measurement of linear expansion coefficient]
Using “TMA / SS6100” manufactured by SII Nano Technology, measurement was performed under a nitrogen atmosphere at a load of 10 mN and a heating rate of 5 ° C./min, and an average linear expansion coefficient (CTE) from 100 ° C. to 200 ° C. was obtained. The inflection point of the linear expansion coefficient curve was defined as the glass transition temperature (Tg).

[Pyrolysis characteristics evaluation]
Using a “TG / DTA6200” manufactured by SII Nanotechnology, a 5% weight loss temperature (Td5) was evaluated under a helium atmosphere at a heating rate of 10 ° C./min.

[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 is measured, and the average value (T) of the transmittance in the wavelength range corresponding to visible light in the range of 780 nm to 380 nm is calculated. Asked. Further, the transmittance at a wavelength of 400 nm (T ₄₀₀ ) and the wavelength at the absorption edge (Cut Off) at which the transmittance is 0.5% or less were determined.

[Toughness evaluation]
The film was completely bent 180 degrees, and the toughness was evaluated using as an index whether cracks occurred.

[Example 1]
In a nitrogen-substituted glass container, 8 ml of a 50:50 mixed solvent of 4 ml of N, N-dimethylacetamide and 4 ml of ethylene carbonate, 0.711 g of 1,4-bis (4-aminobenzoyloxy) benzene (BABB) (2. 04 mmol), 0.500 g (2.55 mmol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and stirring on a hot stirrer at 70 ° C. for 30 minutes to obtain a homogeneous transparent solution Got. After cooling the solution to room temperature, 0.149 g (0.51 mmol) of 1,4-bis (4-aminophenoxy) benzene (BAPB) was added and stirred. The mixture was further stirred for 16 hours to obtain a pale yellow viscous liquid.
This solution was applied onto a PET film using an applicator and dried at 80 ° C. for 1 hour to obtain a polyamic acid film. The polyamic acid film was peeled from the PET film, fixed to a metal frame, and heat-treated at 300 ° C. for 1 hour in a nitrogen atmosphere to perform imidization. The obtained polyimide film had a thickness of 15 μm and excellent toughness.
When the linear expansion coefficient of this film was measured, it showed a considerably low value of 17.5 ppm / ° C. Moreover, the glass transition temperature calculated | required from the inflection point of the curve of a linear expansion coefficient showed 316 degreeC and high heat resistance. Moreover, when the thermal decomposition characteristic was evaluated about this film, 5% weight reduction temperature showed a favorable value with 467 degreeC. When the transparency was evaluated, the average value (T) of the visible light transmittance of 380 nm to 780 nm was 83.2%, the transmittance at 400 nm (T ₄₀₀ ) was 68.6%, and the absorption edge wavelength (Cut Off) was 320 nm, indicating high transparency. The evaluation results are shown in Table 1.

[Examples 2 to 4]
A polyimide film was produced in the same manner as in Example 1 except that the ratio of BABB and BAPB was changed in Example 1. The obtained films all showed high transparency and had excellent toughness. The evaluation results are shown in Table 1.
The FT-IR spectrum of the polyimide film of Example 2 is shown in FIG.

[Example 5]
A polyimide film was produced in the same manner as in Example 1 except that the ratio of BABB and BAPB was changed to 90:10 in Example 1. The obtained film had high transparency and showed a very low coefficient of linear expansion. The evaluation results are shown in Table 1.

[Comparative Example 1]
In Example 1, a polyimide film was prepared in the same manner as in Example 1 except that BABB was not used and 0.745 g (2.55 mmol) of BAPB was used. The obtained polyimide film had almost colorless and transparent toughness, but had a large linear expansion coefficient exceeding 50 ppm / ° C. The evaluation results are shown in Table 1.

  Evaluation results of examples and comparative examples

[Example 6]
In a nitrogen-substituted glass container, 8 ml of a 50:50 mixed solvent of sufficiently dehydrated N-methyl-2-pyrrolidone and γ-butyrolactone, 2,5-bis (4-aminobenzoyloxy) toluene (BABT) 0. 647 g (1.79 mmol) and 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) 0.500 g (2.55 mmol) were mixed and stirred on a hot stirrer at 70 ° C. for 1 hour. A homogeneous transparent solution was obtained. After the solution was cooled to room temperature, 0.224 g (0.77 mmol) of 1,4-bis (4-aminophenoxy) benzene (BAPB) was added and stirred. The mixture was further stirred for 20 minutes on a hot stirrer at 70 ° C. to obtain a pale yellow viscous liquid.
This solution was coated on glass using an applicator and dried at 80 ° C. for 1 hour to obtain a polyamic acid film. The polyamic acid film was peeled from the PET film, fixed to a metal frame, and heat-treated at 300 ° C. for 1 hour in a nitrogen atmosphere to perform imidization. The obtained polyimide film had a thickness of 14 μm and was excellent in toughness.
When the linear expansion coefficient of this film was measured, it showed a low value of 27.2 ppm / ° C. Moreover, the glass transition temperature calculated | required from the inflection point of the curve of a linear expansion coefficient showed high heat resistance with 323 degreeC. Moreover, when the thermal decomposition characteristic was evaluated about this film, the 5% weight loss temperature showed a favorable value with 465 degreeC. When the transparency was evaluated, the average value (T) of the transmittance of visible light from 380 nm to 780 nm was 86.0%, the transmittance at 400 nm (T ₄₀₀ ) was 77.6%, and the absorption edge wavelength (Cut Off) was 320 nm, indicating high transparency.

  The polyimide of the present invention is excellent in transparency and heat resistance, and has a low coefficient of linear expansion. Therefore, it is suitable for films and substrates in the field of optical materials, protective films, insulating films, flexible printed circuit boards in the field of electronic materials, etc. Can be used for

The FT-IR spectrum of the polyimide film of Example 2 is shown. The FT-IR spectrum of the polyimide film of Example 6 is shown.

Claims (5)

Polyimide containing structural units represented by the following formulas (I) and (II).
Formula (I)
[In the formula (I), R represents H or CH ₃ . ]
Formula (II)
  The polyimide of Claim 1 whose ratio of the structural unit shown by said Formula (I) and (II) is 85: 15-25: 75 by molar ratio.   The polyimide of Claim 1 or 2 whose ratio of the structural unit shown by said Formula (I) and (II) is 80: 20-30: 70 by molar ratio. It is a manufacturing method of the polyimide according to any one of claims 1 to 3,
1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,4-bis (4-aminobenzoyloxy) benzene and / or 2,5-bis (4-aminobenzoyloxy) toluene, Reacting 4-bis (4-aminophenoxy) benzene with polyamic acid;
The manufacturing method of a polyimide including the process of imidating the said polyamic acid. Polyamic acid containing structural units represented by the following formulas (III) and (IV).
Formula (III)
[In the formula (III), R represents H or CH ₃ . ]
Formula (IV)