Polyimide precursor resin composition for forming flexible device substrate

Abstract

A polyimide precursor resin composition for forming a flexible device substrate, including a polyamic acid having a structure obtained from a tetracarboxylic acid component including at least one of 3,3,4,4-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride, a diamine component including at least one of paraphenylene diamine and 4,4-diaminodiphenyl ether, and a carboxylic acid monoanhydride, the polyamic acid satisfying equations (1) and (2) below:
0.97X/Y<1.00Equation (1)
0.5(Z/2)/(YX)1.05Equation (2)
in which X represents a number of moles of tetracarboxylic acid component, Y represents a number of moles of diamine component, and Z represents a number of moles of the carboxylic acid monoanhydride.

Claims

1. A method for producing a flexible device substrate, comprising steps of: (A) forming a laminate including a carrier substrate and a polyimide film formed thereon, wherein the laminate is formed by casting a polyimide precursor resin composition comprising a polyamic acid on the carrier substrate, and imidizing the polyamic acid by heat treatment to form a polyimide film, wherein the polyamic acid has a structure obtained from a tetracarboxylic acid component comprising at least one of 3,3,4,4-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride; a diamine component comprising at least one of paraphenylenediamine and 4,4-diaminodiphenyl ether; and a carboxylic acid monoanhydride; wherein the polyamic acid satisfies following equations (1) and (2):
0.97X/Y<1.00Equation (1)
0.5(Z/2)/(YX)1.05Equation (2) wherein X represents a number of moles of tetracarboxylic acid component, Y represents a number of moles of diamine component, and Z represents a number of moles of the carboxylic acid monoanhydride, wherein a peel strength between the carrier substance and the polyimide film is 300 mN/mm or more; (B) forming an inorganic film on the polyimide film; and (C) separating the polyimide film from the carrier substrate to form a flexible device substrate including the polyimide film, wherein the steps are performed in an order of (A), (B), and (C).

2. The method for producing a flexible device substrate according to claim 1, wherein the inorganic film comprises an inorganic material selected from the group consisting of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium oxide, and zirconium oxide.

3. The method for producing a flexible device substrate according to claim 1, further comprising (D) forming a TFT, wherein the steps are performed in an order of (A), (B), (D), and (C).

4. The method for producing a flexible device substrate according to claim 1, wherein the carrier substrate is selected from a glass substrate and a metal substrate.

5. The method for producing a flexible device substrate according to claim 1, wherein a content of 3,3,4,4-biphenyltetracarboxylic dianhydride is 40 mol % or more in the tetracarboxylic acid component.

6. The method for producing a flexible device substrate according to claim 1, wherein a content of paraphenylenediamine is 40 mol % or more in the diamine component.

7. The method for producing a flexible device substrate according to claim 1, wherein the carboxylic acid monoanhydride is phthalic anhydride or maleic anhydride.

8. A method for manufacturing a flexible device, comprising: manufacturing the flexible device substrate according to claim 1; and forming a circuit on the flexible device substrate.

Description

EXAMPLE

(1) Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the examples below.

(2) The method of measuring the characteristics used in the following examples is shown below.

(3) <Solution Viscosity>

(4) Using an E-type rotational viscometer, the solution viscosity at 25 C. and at 10 rpm was measured.

(5) <Viscosity Stability>

(6) A sample having a viscosity-change ratio of the solution viscosity of 5% or less after being kept at 25 C. for 30 days was marked with (good), and other samples were marked with x (bad).

(7) <Peeling Strength Between Layers of Laminate (Delamination Strength of Laminate)>

(8) Measurements were carried out by 90 peel test described in JIS K6854-1, with a sample width of 10 mm and a crosshead speed of 50 mm/min.

(9) The abbreviations of the compounds used in the following examples are as follows. s-BPDA: 3,3,4,4-bip henyltetracarboxylic dianhydride PMDA: pyromellitic dianhydride PPD: p-phenylenediamine ODA: 4,4-diaminodiphenyl ether PEPA: 4-phenylethynyl phthalic anhydride NMP: N-methyl-2-pyrrolidone -APS: 3-aminopropyltriethoxysilane

(10) The amounts of compounds used in the examples below are expressed in molar proportions. The total amount of the diamine is 100 mol %, and the amounts of the other compounds are represented by the molar ratio with respect to the total amount of the diamine.

Example 1

(11) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (98 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, phthalic anhydride (2 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 3.0 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(12) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m. No blistering was observed in the obtained polyimide/glass laminate, and the 90 peel strength between the polyimide film and the glass substrate in the laminate was 538 mN/mm.

Example 2

(13) A SiOx film was formed on the polyimide film of the polyimide/glass laminate obtained in Example 1 by chemical vapor deposition (CVD). The polyimide precursor resin composition obtained in Example 1 was spin-coated on this SiOx film. The coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature, and a polyimide film having a thickness of 10 m is further formed to form a laminate having two polyimide layers. above was obtained. No blistering was observed in this laminate, and the 90 peel strength between the SiOx layer of this laminate and the polyimide layer laminated thereon was 499 mN/mm.

Example 3

(14) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (98 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Thereafter, phthalic anhydride (4 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 2.9 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(15) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, and the 90 peel strength between the polyimide film and the glass substrate in the laminate was 512 mN/mm.

Example 4

(16) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (98 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, maleic anhydride (4 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 3.1 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(17) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, and the 90 peel strength between the polyimide film and the glass substrate in the laminate was 282 mN/mm.

Comparative Example 1

(18) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (100 mol %) was added and the mixture was further stirred for 30 minutes to obtain a liquid polyimide precursor resin composition having a viscosity of 1.1 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(19) The obtained liquid polyimide precursor resin composition was spin-coated on a 6-inch silicon substrate having a thickness of 625 m, followed by baking for 2 minutes on a hot plate at 130 C. to form a film having a thickness of 5 m. Then, using a curing furnace, it was heated and cured at 200 C. for 30 minutes and further at 350 C. for 60 minutes to imidize and obtain a polyimide film. The film thickness after imidization was 3 m. No blistering was observed in this laminate, but the 90 peel strength between the polyimide film and the silicon substrate was 10 mN/mm, and almost no adhesion was observed.

Comparative Example 2

(20) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (99.5 mol %) and silane coupling agent -APS (0.5 mol %) were added, and the mixture was stirred for another 30 minutes to obtain a liquid polyimide precursor resin composition having a viscosity of 19.0 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was x (bad).

(21) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. A SiOx film was formed on the polyimide film of the obtained polyimide/glass laminate by chemical vapor deposition (CVD). The prepared polyimide precursor resin composition was spin-coated on the SiOx film again. The coating film was heat-treated at 120 C., 150 C., 200 C., 250 C. and 500 C. for 10 minutes at each temperature to further form a polyimide film having a thickness of 10 m, and thus a laminate having two polyimide layers was obtained. No blistering was observed in this laminate, but the 90 peel strength between the SiOx layer and the polyimide layer laminated thereon in the laminate was 4 mN/mm, meaning that they were not adhered practically.

Comparative Example 31

(22) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and the mixture was heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (98 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Thereafter, phthalic anhydride (8 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 3.2 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(23) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, but the 90 peel strength could not be measured because the polyimide film was very fragile.

Comparative Example 4

(24) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (97 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Thereafter, phthalic anhydride (2 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 2.8 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(25) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, but the 90 peel strength could not be measured because the polyimide film was very fragile.

Comparative Example 5

(26) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and the mixture was heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (96.1 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, phthalic anhydride (7.8 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 3.0 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(27) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, but the 90 peel strength could not be measured because the polyimide film was very fragile.

Comparative Example 6

(28) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and the mixture was heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (92.4 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, phthalic anhydride (13.9 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 3.1 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(29) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, but the 90 peel strength could not be measured because the polyimide film was very fragile.

Example 5

(30) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (97 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, phthalic anhydride (3 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 1.4 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(31) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, and the 90 peel strength between the polyimide film and the glass substrate in the laminate was 417 mN/mm.

Example 6

(32) PPD (100 mol %) and NMP were charged into a reaction vessel substituted with nitrogen gas, and the mixture was heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (98 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, PEPA (4 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 4.4 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(33) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, and the 90 peel strength between the polyimide film and the glass substrate of this laminate was 318 mN/mm.

Example 7

(34) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and the mixture was heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (99.5 mol %) was added and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, phthalic anhydride (1 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 4.4 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(35) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, and the 90 peel strength between the polyimide film and the glass substrate in the laminate was 417 mN/mm.

Example 8

(36) ODA (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and the mixture was heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (98 mol %) was added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, phthalic anhydride (4 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 3.3 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(37) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 400 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, and the 90 peel strength between the polyimide film and the glass substrate in the laminate was 608 mN/mm.

Example 9

(38) PPD (50 mol %), ODA (50 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and the mixture was heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (39.2 mol %) and PMDA (58.8 mol %) were added, and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, phthalic anhydride (4 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 2.0 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(39) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 400 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, and the 90 peel strength between the polyimide film and the glass substrate in the laminate was 288 mN/mm.

Comparative Example 7

(40) PPD (100 mol %) and NMP were charged into a reaction vessel purged with nitrogen gas, and heated and stirred for 15 minutes at 40 C. to dissolve the monomer. Then, s-BPDA (98 mol %) was added and the mixture was further stirred for 30 minutes to obtain a polyamic acid solution. Then, phthalic anhydride (4.5 mol %) was added to the polyamic acid solution to obtain a liquid polyimide precursor resin composition having a viscosity of 4.4 Pa.Math.s (25 C.). This polyimide precursor resin composition was allowed to stand at 25 C. for 30 days, and the viscosity stability was evaluated. The evaluation result was (good).

(41) The prepared polyimide precursor resin composition was spin-coated on a glass substrate, and the coated film was heat-treated at 120 C., 150 C., 200 C., 250 C., and 500 C. for 10 minutes at each temperature to form a polyimide film having a thickness of 10 m on the glass substrate. No blistering was observed in the obtained polyimide/glass laminate, but the 90 peel strength could not be measured because the polyimide film was very fragile.

(42) TABLE-US-00001 TABLE 1 Compar- Compar- Compar- Compar- ative- ative- ative- ative- Exam- Exam- Exam- Exam- Example Example Example Example ple 1 ple 2 ple 3 ple 4 1 2 3 4 acid s-BPDA 98 98 98 98 100 99.5 98 97 dianhydride PMDA (mol %) acid phthalic 2 2 4 8 2 monoanhydride anhydride (%) maleic 4 anhydride PEPA diamine PPD 100 100 100 100 100 100 100 100 (mol %) ODA value of equations (1) 0.98 0.98 0.98 0.98 1.00 0.995 0.98 0.97 value of equations (2) 0.50 0.50 1.00 1.00 0.00 2.00 0.33 silane coupling agent none none none none none -APS none none viscosity stability x material of substrate glass SiO.sub.x glass glass silicon SiO.sub.x glass glass peel strength 538 499 512 282 10 4 The measurement was (mN/mm) not possible because the polyimide film was very fragile. Compar- Compar- ative- ative- Compar- Example Example Exam- Exam- Exam- Exam- Exam- ative- 5 6 ple 5 ple 6 ple 7 ple 8 ple 9 Example 7 acid s-BPDA 96.1 92.4 97 98 99.5 98 39.2 98 dianhydride PMDA 58.8 (mol %) acid phthalic 7.8 13.9 3 1 4 4 4.5 monoanhydride anhydride (%) maleic anhydride PEPA 4 diamine PPD 100 100 100 100 100 50 100 (mol %) ODA 100 50 value of equations (1) 0.96 0.92 0.97 0.98 0.995 0.98 0.98 0.98 value of equations (2) 1.00 0.91 0.50 1.00 1.00 1.00 1.00 1.13 silane coupling agent none none none none none none none none viscosity stability material of substrate glass glass glass glass glass glass glass glass peel strength The measurement was 417 318 417 608 288 The (mN/mm) not possible because measurement the polyimide film was not was very fragile. possible.

INDUSTRIAL APPLICABILITY

(43) The polyimide precursor resin composition of the present invention gives a polyimide film having excellent peel strength to a substrate without containing a silane coupling agent, and can be suitably used as a substrate of flexible devices, for example, display devices such as a liquid crystal display, an organic EL display, or electronic paper, and light receiving devices such as a light receiving element of a thin film solar cell.