Polyimide precursor composition

Abstract

A polyimide precursor composition that exhibits excellent tensile strength and breaking elongation, and that provides a film containing an alicyclic polyimide resin; a method for producing a polyimide film using the polyimide precursor composition; and a permanent film that contains an alicyclic polyimide resin and that exhibits excellent tensile strength and breaking elongation. The polyimide precursor composition is a mixture of a resin precursor component which is a polyamic acid including an alicyclic backbone having a predetermined structure, a monomer component that includes an aromatic diamine compound having a predetermined structure or an alicyclic tetracarboxylic acid di-anhydride having a predetermined structure; an imidazole compound having a predetermined structure; and a solvent.

Claims

1. A polyimide precursor composition comprising an imidazole compound (A), a resin precursor component (B), and a solvent (S), wherein the imidazole compound (A) is a compound represented by the following formula (1): ##STR00054## wherein, in the formula (1), R.sup.1 is a hydrogen atom or an alkyl group, R.sup.2 is an optionally substituted aromatic group, R.sup.3 is an optionally substituted alkylene group, R.sup.4 each independently represent a halogen atom, a hydroxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphonato group, or an organic group, n is an integer of 0 to 3; and the resin precursor component (B) is at least one selected from the group consisting of (a) and (b): wherein (a) is a monomer component containing a diamine compound represented by the following formula (2):
H.sub.2NR.sup.b10NH.sub.2(2) wherein, in the formula (2), R.sup.b10 is an aryl group having 6 to 40 carbon atoms, and norbornane-2-spiro--cycloalkanone--spiro-2-norbornane-5,5,6,6-tetracarboxylic dianhydrides represented by the following formula (b1): ##STR00055## wherein, in the formula (b1), R.sup.b1, R.sup.b2, and R.sup.b3 each independently represent one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluorine atom, and m represents an integer of 0 to 12, and wherein (b) is a polyamic acid including a repeating unit represented by the following formula (b2): ##STR00056## wherein, in the formula (b2), R.sup.b1, R.sup.b2, and R.sup.b3 each independently represent one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluorine atom, R.sup.b10 represents an aryl group having 6 to 40 carbon atoms, and m represents an integer of 0 to 12.

2. The polyimide precursor composition according to claim 1, further comprising one or more silicon-containing compounds selected from the group consisting of a silicon-containing resin, a silicon-containing resin precursor, and a silane coupling agent.

3. A method for producing a polyimide film, comprising: forming a coating film of the polyimide precursor composition according to claim 1; and heating the coating film to ring-close a polyamic acid derived from a resin precursor component (B) in the coating film.

4. A polyimide film comprising an imidazole compound (A) and a polyimide resin, wherein the imidazole compound (A) is a compound represented by the following formula (1): ##STR00057## wherein, in the formula (1), R.sup.1 is a hydrogen atom or an alkyl group, R.sup.2 is an optionally substituted aromatic group, R.sup.3 is an optionally substituted alkylene group, R.sup.4 each independently represent a halogen atom, a hydroxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphonato group, or an organic group, and n is an integer of 0 to 3; and the polyimide resin is a resin in which polyamic acid composed of a repeating unit represented by the following formula (b2): ##STR00058## wherein, in the formula (b2), R.sup.b1, R.sup.b2, and R.sup.b3 each independently represent one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluorine atom, R.sup.b10 represents an aryl group having 6 to 40 carbon atoms, and m represents an integer of 0 to 12 is ring-closed.

Description

EXAMPLES

(1) The present invention will be specifically described below by way of Examples, but the scope of the present invention is not limited to these Examples.

Synthesis Example 1

(2) In Synthesis Example 1, an imidazole compound (A1) having the following structure was synthesized.

(3) ##STR00049##

(4) First, 30 g of a cinnamic acid derivative having the following structure was dissolved in 200 g of methanol, and 7 g of potassium hydroxide was added in methanol. Then, the methanol solution was stirred at 40 C. After distilling off methanol, the residue was suspended in 200 g of water. The suspension thus obtained was mixed with 200 g of tetrahydrofuran, followed by stirring and further separation of an aqueous phase. Under ice cooling, 4 g of hydrochloric acid was added. After stirring, 100 g of ethyl acetate was mixed, followed by stirring. After the mixed solution was left to stand, an oil phase was separated. The objective product was crystallized from the oil phase, and the precipitate was recovered to obtain an imidazole compound (A1) having the above structure.

(5) ##STR00050##

(6) The measurement results of .sup.1H-NMR of the imidazole compound (A1) having the above structure are as mentioned below.

(7) .sup.1H-NMR (DMSO): 11.724 (s, 1H), 7.838 (s, 1H), 7.340 (d, 2H, J=4.3 Hz), 7.321 (d, 1H, J=7.2 Hz), 6.893 (d, 2H, J=4.3 Hz), 6.876 (d, 1H, J=6.1 Hz), 5.695 (dd, 1H, J=4.3 Hz, 3.2 Hz), 3.720 (s, 3H), 3.250 (m, 2H)

Example 1

(8) <Preparation of Tetracarboxylic Dianhydride>

(9) In accordance with the methods mentioned in Synthesis Example 1, Example 1 and Example 2 of WO 2011/099518 A, a tetracarboxylic dianhydride (norbornane-2-spiro--cyclopentanone--spiro-2-norbornane-5,5,6,6-tetracarboxylic dianhydride) represented by the following formula was prepared.

(10) ##STR00051##
<Preparation of Polyamic Acid>

(11) First, a 30 ml three-necked flask was sufficiently dried by heating using a heat gun. Then, the three-necked flask was purged with nitrogen to replace an atmospheric gas in the three-necked flask with a nitrogen atmosphere. In the three-necked flask, 0.2045 g of 4,4-diaminobenzanilide (0.90 mmol, DABAN manufactured by Nipponjunryo Chemicals Co., Ltd.) was added and 3.12 g of N,N,N,N-tetramethylurea (TMU) was added. Contents in the three-necked flask were stirred to obtain a slurry solution in which an aromatic diamine (DABAN) is dispersed in TMU. After adding 0.3459 g (0.90 mmol) of tetracarboxylic dianhydride of the above formula in the three-necked flask, contents in the flask were stirred under a nitrogen atmosphere at room temperature (25 C.) for 12 hours to obtain a reaction solution. The reaction solution thus obtained contains 15% by mass (TMU solvent: 85 parts by mass) of a polyamic acid.

(12) <Addition Step of Imidazole Compound (A)>

(13) To the thus obtained reaction solution, the imidazole compound A1 (0.206 g, 5.6 parts by mass based on 100 parts by mass of the reaction solution) obtained in Synthesis Example 1 was added under a nitrogen atmosphere. Then, the reaction solution was stirred at 25 C. for 12 hours to obtain a liquid polyimide precursor composition including an imidazole compound (A) and a polyamic acid.

(14) <Preparation of Polyimide Film>

(15) On a glass substrate (large-sized slide glass, manufactured by Matsunami Glass Ind., Ltd. under the trade name of S9213, having a size of 76 mm in length, 52 mm in width, and 1.3 mm in thickness), the thus obtained polyimide precursor composition was spin-coated so that the thickness of a coating film after curing under heat became 13 m to form a coating film. Then, the glass substrate having the coating film formed thereon was placed on a hot plate at 60 C. and left to stand for 2 hours, whereby, the solvent was removed by vaporization from the coating film. After removal of the solvent, the glass substrate having the coating film formed thereon was placed in an inert oven in which nitrogen flows at a flow rate of 3 L/minute. In the inert oven, the coated glass substrate was left to stand under a nitrogen atmosphere at a temperature of 25 C. for 0.5 hour, followed by heating at a temperature of 135 C. for 0.5 hour and further heating at a temperature of 300 C. (final heating temperature) for 1 hour to thereby cure the coating film, thus obtaining a polyimide coated glass in which a thin film of a polyimide (polyimide film) is coated on the glass substrate.

(16) The polyimide coated glass thus obtained was immersed in hot water at 90 C. to thereby peel off a polyimide film from the glass substrate to obtain a polyimide film (film having a size of 76 mm in length, 52 mm in width, and 13 m in thickness).

(17) To identify a molecular structure of a resin which is the material of the thus obtained polyimide film, IR spectrum of a sample of the polyimide film was measured by using an IR spectrometer (manufactured by JASCO Corporation under the trade name of FT/IR-4100). The measurement results revealed that CO stretching vibration of imidocarbonyl is observed at 1696.2 cm.sup.1 in IR spectrum of the resin which is the material of the polyimide film. The molecular structure identified based on these results revealed that the thus obtained polyimide film is surely formed of a polyimide resin.

(18) With respect to the thus obtained polyimide film, in accordance with the following method, measurements were made of the coefficient of thermal expansion (CTE), the tensile strength and elongation at break, the glass transition temperature of a polyimide resin, the total light transmittance, the Haze (turbidity), and the yellowness index (YI). These evaluation results are shown in Table 1.

(19) <Measurement of Coefficient of Thermal Expansion>

(20) The coefficient of thermal expansion of the polyimide film is desirably 20 ppm/K or less. If such coefficient of thermal expansion exceeds the upper limit, peeling easily occurs due to thermal history when a composite material is fabricated by using metal having a coefficient of thermal expansion in a range of 5 to 20 ppm/K in combination of an inorganic substance. From the viewpoint of sufficiently suppressing peeling from occurring due to thermal history and of being capable of more improving the dimensional stability, the coefficient of thermal expansion of such polyimide film is more preferably 20 to 20 ppm/K, and still more preferably 0 to 15 ppm/K. When such coefficient of thermal expansion is less than the lower limit, peeling and curling may easily occur. The following value is employed as the value of the coefficient of thermal expansion of such polyimide film. First, with respect to the polyimide film as the measuring object, a film having a size of 76 mm in length, 52 mm in width, and 13 m in thickness, formed of the material, which is the same as the material forming a polyimide film thereof (polyimide), is formed. Then, the film is vacuum-dried (at 120 C. for 1 hour) and subjected to a heat treatment under a nitrogen atmosphere at 200 C. for 1 hour to obtain a dry film. Using the thus obtained dry film as a sample and employing a thermomechanical analyzer (manufactured by Rigaku Corporation under the trade name of TMA8310) as a measuring device, change of length in the longitudinal direction 50 C. to 200 C. of the sample is measured under a nitrogen atmosphere under the conditions of a tensile mode (49 mN) and a temperature rise rate of 5 C./minute to determine an average of change of length per 1 C. (1K) in a temperature range of 50 C. to 200 C. Then, the average thus determined is employed as the value of the coefficient of thermal expansion of the polyimide film of the present invention (the value of the coefficient of thermal expansion of the polyimide film having a thickness of 13 m is employed as the value of the coefficient of thermal expansion of the polyimide film of the present invention).

(21) <Measurement of Tensile Strength and Elongation at Break>

(22) The tensile strength (unit: MPa) and the elongation at break (unit: %) of the polyimide film (thickness of 13 m) were measured in accordance with the following methods. First, Super Dumbbell Cutter (trade name) (Model: SDMK-1000-D, in accordance with A22 standard of JIS K7139 (issued in 2009)) manufactured by DUMBBELL CO., LTD. was attached to an SD type lever-controlled sample cutter (cutter (Model: SDL-200), manufactured by DUMBBELL CO., LTD.), and then a polyimide film was cut so as to have a size of 75 mm in total length, 57 mm in distance between the tab portions, 30 mm in length of the parallel portion, 30 mm in radius of the shoulder portion, 10 mm in width of the end portion, 5 mm in width of the central parallel portion, and 13 m in thickness to fabricate a Dumbbell-shaped specimen (specimen fabricated in accordance with the standard of JIS K7139 type A22 (scale specimen), except that the thickness was set at 13 m) as a measurement sample. After disposing the measurement sample so as to set a width between holding tools at 57 mm and a width of the holding portion at 10 mm (total width of the end portion), a tensile test of pulling a measurement sample under the conditions of a full-scale load of 0.05 kN and a test speed of 1 to 300 mm/minute was performed using a Tensilon universal-testing machine (manufactured by A&D Company, Limited, Model UCT-10T) to determine the tensile strength and the elongation at break. The above test is a test in accordance with JIS K7162 (issued in 1994). The value of the elongation at break (%) was determined by calculation of the following equation:
[Elongation at break (%)]={(LL.sub.0)/L.sub.0}100
where L.sub.0 is a length of the parallel portion of the specimen (=length of the parallel portion: 30 mm) and L is a length of the parallel portion of the specimen until it breaks (length of the parallel portion of the specimen when it breaks: 30 mm+).
<Measurement of Glass Transition Temperature (Tg)>

(23) Using a thermomechanical analyzer (manufactured by Rigaku Corporation under the trade name of TMA8311), the value (unit: C.) of a glass transition temperature (Tg) of a polyimide resin, which is the material of a polyimide film, was measured by penetrating a pin made of transparent quartz (tip diameter of 0.5 mm) under pressure of 500 mN into the film under a nitrogen atmosphere at a temperature rise rate 5 C./minute in a temperature range of 30 C. to 550 C. (scanning temperature) (measurement by a so-called penetration method). With respect to the material of films formed by using polyimide precursor compositions of all Examples and Comparative Examples, no glass transition temperature could be confirmed.

(24) <Measurement of Total Light Transmittance, Haze (Turbidity), and Yellowness Index (YI)>

(25) Using Haze Meter NDH-5000 (trade name, manufactured by Nippon Denshoku Industries Co., Ltd.) as a measuring device, the value of total light transmittance (unit: %), Haze (turbidity), and yellowness index (YI) were determined by measuring in accordance with JIS K7361-1 (issued in 1997).

Examples 2 to 8, Comparative Example 1 and Comparative Example 2

(26) In the same manner as in Example 1, except that the amount of the imidazole compound A1 as the component (A) is changed to the amount shown in Table 1 and the solvent shown in Table 1 is used as the solvent (S), polyimide precursor compositions were obtained. Namely, the imidazole compound A1 was added in the amount (parts by mass) shown in Table 1 based on 100 parts by mass of the total of the polyamic acid obtained by preparation of the polyamic acid and the solution of the solvent shown in Table 1. In Example 7, the imidazole compound A1 was added to the reaction solution during preparation of the polyamic acid. Namely, 4.5 parts by mass of the imidazole compound A1 was added to 100 parts by mass of a mixed solution of polyamic acid (molecular weight of about 8,000), 4,4-diaminobenzanilide, norbornane-2-spiro--cyclopentanone--spiro-2-norbornane-5,5,6,6-tetracarboxylic dianhydride, and the solvent shown in Table 1.

(27) Using the polyimide precursor compositions of the respective Examples and Comparative Examples, a polyimide film was formed in the same manner as in Example 1. In Example 8, curing conditions of the coating film are as follows: 80 C.30 minutes, 300 C.30 minutes, and 380 C.30 minutes. With respect to the thus obtained polyimide film, in the same manner as in Example 1, measurements were made of the coefficient of thermal expansion, the tensile strength and elongation at break, the glass transition temperature of a polyimide resin, the total light transmittance, the Haze (turbidity), and the yellowness index (YI). These evaluation results are shown in Table 1.

(28) TABLE-US-00001 TABLE 1 (A) Component Solvent (S) Total light Tensile Elongation Parts by Parts by Tg CTE Yellowness transmittance Haze strength at break mass Type mass ( C.) (ppm/K) index (%) (%) (MPa) (%) Example 1 5.6 TMU 85 N.D. 11.0 3.5 88.1 0.5 177 14.9 Example 2 4.5 TMU 85 N.D. 12.7 2.8 88.0 0.6 142 9.1 Example 3 3.4 TMU 85 N.D. 10.8 2.6 88.1 0.4 121 5.7 Example 4 2.3 TMU 85 N.D. 11.5 2.7 88.1 0.3 109 4.3 Example 5 1.1 TMU 85 N.D. 10.6 2.8 88.1 0.5 75 3.1 Example 6 4.5 DMAc 85 N.D. 12.4 3.3 88.0 0.2 157 9.0 Example 7 4.5 TMU 85 N.D. 10.5 2.2 88.2 0.5 127 9.0 Example 8 4.5 TMU 85 N.D. 12.1 3.7 88.8 0.3 224 37.9 Comparative None TMU 85 N.D. 10.8 3.2 87.4 0.7 53 1.9 Example 1 Comparative None DMAc 85 N.D. 11.0 3.2 87.6 0.6 42 2.0 Example 2

(29) As is apparent from Table 1, use of the polyimide precursor compositions of Examples, which includes an imidazole compound having a predetermined structure represented by the formula (1) as the component (A), enables formation of a polyimide film which has high heat resistance, and having satisfactory tensile strength and elongation at break, high total light transmittance, and low yellowness index and Haze. Meanwhile, as is apparent from Comparative Examples, when the polyimide precursor composition does not include an imidazole compound having a predetermined structure represented by the formula (1) as the component (A), it is possible to form only a polyimide film having low tensile strength and elongation at break.

Example 9 to Example 13

(30) In Example 9, the polyimide precursor composition obtained in Example 1 was used. In Examples 10 to 13, a composition, prepared by adding the following silicon-containing compounds D1 to D4, as an additive, in the amount shown in Table 2 based on 100 parts by mass of the solid content in the polyimide precursor composition in Example 1, was used. In the same manner as in <Preparation of Polyimide Film> of Example 1, except that using the thus obtained respective polyimide precursor compositions, laser peeling (excimer laser peeling with 308 nm line beam, overlap of line beam: 50%) was performed in the energy amount shown in Table 2, a polyimide film was obtained. Evaluation was made on adhesion of a polyimide film to glass as a substrate, cloudiness when laser peeling is performed, and peelability. The results are also shown in Table 2.

(31) TABLE-US-00002 TABLE 2 Additive Exposure dose [Parts by 100 mJ/cm.sup.2 90 mJ/cm.sup.2 85 mJ/cm.sup.2 mass] Adhesion Cloudiness Peelability Cloudiness Peelability Cloudiness Peelability Example 9 None Weak Slight Ordinary Slight Ordinary None Ordinary (0) B B B B A B Example 10 D-1 Medium Slight Satisfactory None Ordinary None Ordinary [1.5] (2) B A A B A B Example 11 D-2 Strong Slight Satisfactory Slight Satisfactory None Satisfactory [1.5] (3) B A B A A A Example 12 D-3 Little Slight Satisfactory Slight Ordinary None Ordinary [1.5] (1) B A B B A B Example 13 D-4 Strong Slight Satisfactory Slight Satisfactory None Satisfactory [1.5] (3) B A B A A A

(32) Additives D-1 to D-4 shown in Table 2 are as follows. D-1: Silane coupling agent of the following formula

(33) ##STR00052##

(34) D-2: Silane coupling agent of the following formula

(35) ##STR00053##

(36) D-3: Chain polysilane having a silanol group bonded to a silicon atom, a phenyl group, and a methyl group (mass average molecular weight of 1,500)

(37) D-4: 3-Aminopropyltriethoxysilane

(38) [Evaluation] In accordance with the following criteria, valuation was made on adhesion of polyimide films obtained in Example 9 to Example 13 to a glass substrate, cloudiness when laser peeling is performed, and peelability. Newton's rings in peelability evaluation mean a phenomenon confirmed when a gap occurs between glass and film during laser peeling, leading to interference of light.

(39) (Adhesion)

(40) 0: A polyimide film is easily peelable from a glass substrate with a very weak force without feeling peeling resistance.

(41) 1: Although feeling weak peeling resistance, a polyimide film is peelable from a glass substrate with a weak force.

(42) 2: Although feeling strong peeling resistance, a polyimide film is peelable from a glass substrate with a strong force.

(43) 3: A polyimide film is not peelable from a glass substrate even with a very strong force, or breakage of the polyimide film occurs when peeling the polyimide film from the glass substrate, thus remaining the polyimide film on the glass substrate.

(44) (Cloudiness)

(45) A: Not visually confirmed B: Visually confirmed slightly C: Visually confirmed
(Peelability) A: Newton's rings are confirmed B: Newton's rings are slightly confirmed C: Newton's rings are not confirmed

(46) As is apparent from Table 2, when the silicon-containing compound is added to the polyimide precursor composition (Examples 10 to 13), adhesion of the thus formed polyimide film to the glass substrate could be improved as compared to the case where no silicon-containing compound is added (Example 9). It has been confirmed that it is possible to suppress cloudiness due to UV laser peeling to be equal to or greater than the case of adding no silicon-containing compound even in a state of high substrate adhesion. In Example 10 and Example 13, satisfactory peelability was exhibited even in an exposure dose with low energy. In Example 10 and Example 13, strongest adhesion was achieved. Because of satisfactory peelability, additives (D-2, D-4) used can be said to be additives which are excellent in glass adhesion while sufficiently maintaining the strength of the polyimide film, and are particularly effective as additives for laser abrasion (which are free from cloudiness and are laser peelable).

(47) (Total Light Transmittance and Haze (Turbidity))

(48) In the same manner as in Example 1, except that the diamine component was changed from only DABAN to a mixed component (molar ratio (DABAN:X-22-9409=98:2)) of DABAN and a both-end amino-modified methyl phenyl silicone (X-22-9409, manufactured by Shin-Etsu Chemical Co., Ltd.), a polyimide film was formed. The results revealed that a polyimide film having a total light transmittance of 89.9% and Haze of 0.3 is obtained.