Curable resin composition, cured product, adhesive, bonding film, coverlay film, flexible copper-clad laminate and circuit board

Abstract

The present invention aims to provide a curable resin composition capable of providing a cured product that has a high glass transition temperature after curing and is excellent in thermal decomposition resistance, adhesiveness, and long-term heat resistance. The present invention also aims to provide a cured product of the curable resin composition, an adhesive containing the curable resin composition, and an adhesive film, a coverlay film, a flexible copper clad laminate, and a circuit board each formed using the curable resin composition. Provided is a curable resin composition containing: a curable resin; an imide oligomer having an imide skeleton in a main chain and a crosslinkable functional group at an end and having a number average molecular weight of 4,000 or less; and a curing accelerator, a cured product of the curable resin composition having an initial adhesive force to polyimide of 3.4 N/cm or more, the cured product after storage at 200° C. for 100 hours having an adhesive force to polyimide of at least 0.8 times the initial adhesive force.

Claims

1. A curable resin composition comprising: a curable resin; an imide oligomer composition containing an imide oligomer having an imide skeleton in a main chain and a crosslinkable functional group at an end and having a number average molecular weight of 4,000 or less; and a curing accelerator, a cured product of the curable resin composition having an initial adhesive force to polyimide of 3.4 N/cm or more, the cured product after storage at 200° C. for 100 hours having an adhesive force to polyimide of at least 0.8 times the initial adhesive force, wherein the imide oligomer composition has an imidization ratio of 70% or more and 98% or less, and the imide oligomer is an imide oligomer containing no siloxane skeleton in its structure and contains a structure of the following formula (1-1): ##STR00020## wherein, A is a tetravalent group of the following formula (2-1) or the following formula (2-2); and B is a divalent group of the following formula (14), the following formula (15), or the following formula (16), ##STR00021## wherein, in the formula (2-1), the formula (2-2), the formula (14), the formula (15), and the formula (16), * is a binding site; in the formula (2-1), Z is a bond, an oxygen atom, or a substituted or unsubstituted divalent hydrocarbon group that may have an oxygen atom at a binding site; and in the formula (2-1) and the formula (2-2), a hydrogen atom of an aromatic ring may be replaced.

2. The curable resin composition according to claim 1, which contains the imide oligomer in an amount of 20% by weight or more and 80% by weight or less relative to the total weight of the curable resin, the imide oligomer, and the curing accelerator.

3. The curable resin composition according to claim 1, wherein the curable resin is liquid at 25° C.

4. The curable resin composition according to claim 1, wherein the curable resin contains an epoxy resin.

5. The curable resin composition according to claim 1, wherein the crosslinkable functional group is a functional group capable of reacting with an epoxy group.

6. The curable resin composition according to claim 1, which contains the curing accelerator in an amount of 0.8% by weight or more relative to the total weight of the curable resin, the imide oligomer, and the curing accelerator.

7. The curable resin composition according to claim 1, wherein the curable resin composition has a tack value at 60° C. of at least 2 times the tack value at 25° C.

8. The curable resin composition according to claim 1, wherein the curable resin composition has a surface free energy of 40 mJ/m.sup.2 or more.

9. The curable resin composition according to claim 1, wherein the cured product after storage in an environment at 85° C. and 85% RH for 24 hours has an adhesive force to polyimide of at least 0.8 times the initial adhesive force.

10. The curable resin composition according to claim 7, wherein the curable resin is liquid at 25° C.

11. The curable resin composition according to claim 7, wherein the curable resin contains at least one selected from the group consisting of an epoxy resin, a phenolic resin, a silicone resin, a fluororesin, a polyimide resin, a maleimide resin, and a benzoxazine resin.

12. The curable resin composition according to claim 1, comprising a nonpolar solvent having a boiling point of 120° C. or lower or an aprotic polar solvent having a boiling point of 120° C. or lower.

13. A cured product of the curable resin composition according to claim 1.

14. The cured product according to claim 13, which has a weight reduction ratio at 330° C. of less than 2.5%.

15. The cured product according to claim 13, which has a glass transition temperature of 150° C. or higher.

16. An adhesive comprising the curable resin composition according to claim 1.

17. An adhesive film comprising the curable resin composition according to claim 1.

18. A coverlay film comprising: a substrate film; and a layer containing the curable resin composition according to claim 1 formed on the substrate film.

19. A flexible copper clad laminate comprising: a substrate film; a layer containing the curable resin composition according to claim 1 formed on the substrate film; and copper foil.

20. A circuit board comprising: the cured product according to claim 13.

Description

DESCRIPTION OF EMBODIMENTS

(1) Embodiments of the present invention are specifically described in the following with reference to, but not limited to, examples.

SYNTHESIS EXAMPLE 1

Preparation of Imide Oligomer Composition A

(2) An amount of 34.5 parts by weight of 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene (available from Mitsui Fine Chemicals, Inc., “Bisaniline M”) was dissolved in 400 parts by weight of N-methylpyrrolidone (available from Wako Pure Chemical Industries, Ltd., “NMP”). To the obtained solution was added 62.0 parts by weight of 3,4′-oxydiphthalic dianhydride (available from Tokyo Chemical Industry Co., Ltd., “3,4′-ODPA”), followed by stirring at 25° C. for two hours to cause reaction to give an amic acid oligomer solution. N-Methylpyrrolidone was removed from the obtained amic acid oligomer solution under reduced pressure, followed by heating at 300° C. for two hours to give an imide oligomer composition A (imidization ratio: 92a).

(3) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition A contained an imide oligomer having a structure of the above formula (1-1) (A is a group of the following formula (13) and B is a group of the following formula (14)). The imide oligomer having a structure of the formula (1-1) had a number average molecular weight of 1,380. The analyses further showed that the imide oligomer composition A contained an imide oligomer of the above formula (4-1) (A is a group of the following formula (13) and B is a group of the following formula (14)) as the imide oligomer having a structure of the formula (1-1).

(4) ##STR00013##

(5) In the formula (13), * is a binding site.

(6) ##STR00014##

(7) In the formula (14), * is a binding site.

SYNTHESIS EXAMPLE 2

Preparation of Imide Oligomer Composition B

(8) An imide oligomer composition B (imidization ratio: 92%) was obtained as in Synthesis Example 1 except that 34.5 parts by weight of 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene was changed to 34.5 parts by weight of 1,4-bis(2-(4-aminophenyl)-2-propyl)benzene (available from Mitsui Fine Chemicals, Inc., “Bisaniline P”).

(9) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition B contained an imide oligomer having a structure of the above formula (1-1) (A is a group of the above formula (13) and B is a group of the following formula (15)). The imide oligomer having a structure of the formula (1-1) had a number average molecular weight of 1,390. The analyses further showed that the imide oligomer composition B contained an imide oligomer of the above formula (4-1) (A is a group of the above formula (13) and B is a group of the following formula (15)) as the imide oligomer having a structure of the formula (1-1).

(10) ##STR00015##

(11) In the formula (15), * is a binding site.

SYNTHESIS EXAMPLE 3

Preparation of Imide Oligomer Composition C

(12) An imide oligomer composition C (imidization ratio: 91%) was obtained as in Synthesis Example 1 except that 34.5 parts by weight of 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene was changed to 29.2 parts by weight of 1,3-bis(3-aminophenoxy)benzene (available from Mitsui Fine Chemicals, Inc., “APB-N”).

(13) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition C contained an imide oligomer having a structure of the above formula (1-1) (A is a group of the above formula (13) and B is a group of the following formula (16)). The imide oligomer composition C had a number average molecular weight of 1,310. The analyses further showed that the imide oligomer composition C contained an imide oligomer of the above formula (4-1) (A is a group of the above formula (13) and B is a group of the following formula (16)) as the imide oligomer having a structure of the formula (1-1).

(14) ##STR00016##

(15) In the formula (16), * is a binding site.

SYNTHESIS EXAMPLE 4

Preparation of Imide Oligomer Composition D

(16) An imide oligomer composition D (imidization ratio:

(17) 93%) was obtained as in Synthesis Example 1 except that 62.0 parts by weight of 3,4′-oxydiphthalic dianhydride was changed to 104.1 parts by weight of 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride (available from Tokyo Chemical Industry Co., Ltd.).

(18) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition D contained an imide oligomer having a structure of the above formula (1-1) (A is a group of the following formula (17) and B is a group of the above formula (14)). The imide oligomer having a structure of the formula (1-1) had a number average molecular weight of 2,020. The analyses further showed that the imide oligomer composition D contained an imide oligomer of the above formula (4-1) (A is a group of the following formula (17) and B is a group of the above formula (14)) as the imide oligomer having a structure of the formula (1-1).

(19) ##STR00017##

(20) In the formula (17), * is a binding site.

SYNTHESIS EXAMPLE 5

Preparation of Imide Oligomer Composition E

(21) An imide oligomer composition E (imidization ratio: 91%) was obtained as in Synthesis Example 4 except that the amount of 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride added was changed to 98.9 parts by weight.

(22) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition E contained an imide oligomer having a structure of the above formula (1-1) (A is a group of the above formula (17) and B is a group of the above formula (14)). The imide oligomer having a structure of the formula (1-1) had a number average molecular weight of 2,520. The analyses further showed that the imide oligomer composition E contained an imide oligomer of the above formula (4-1) (A is a group of the formula (17) and B is a group of the above formula (14)) as the imide oligomer having a structure of the formula (1-1).

SYNTHESIS EXAMPLE 6

Preparation of Imide Oligomer Composition F

(23) An imide oligomer composition F (imidization ratio: 92%) was obtained as in Synthesis Example 1 except that the amount of 3,4′-oxydiphthalic dianhydride added was changed to 65.1 parts by weight.

(24) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition F contained an imide oligomer having a structure of the above formula (1-1) (A is a group of the above formula (13) and B is a group of the above formula (14)). The imide oligomer having a structure of the formula (1-1) had a number average molecular weight of 1,220. The analyses further showed that the imide oligomer composition F contained an imide oligomer of the above formula (4-1) (A is a group of the above formula (13) and B is a group of the above formula (14)) as the imide oligomer having a structure of the formula (1-1).

SYNTHESIS EXAMPLE 7

Preparation of Imide Oligomer Composition G

(25) An amount of 34.5 parts by weight of 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene (available from Mitsui Fine Chemicals, Inc., “Bisaniline M”) was dissolved in 400 parts by weight of N-methylpyrrolidone (available from Wako Pure Chemical Industries, Ltd., “NMP”). To the obtained solution was added 62.0 parts by weight of 3,4′-oxydiphthalic dianhydride (available fom Tokyo Chemical Industry Co., Ltd., “3,4′-ODPA”), followed by stirring at 25° C. for two hours to cause reaction to give an amic acid oligomer solution. The amic acid oligomer solution was heated at 180° C. for three hours in N-methylpyrrolidone while removing with a Dean-Stark tube the water generated from imidization, and then N-methylpyrrolidone was removed under reduced pressure. Thus, an imide oligomer composition G (imidization ratio: 23%) was obtained.

(26) .sup.111-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition G contained an imide oligomer having a structure of the above formula (1-1) (A is a group of the above formula (13) and B is a group of the above formula (14)). The imide oligomer having a structure of the formula (1-1) had a number average molecular weight of 1,400. The analyses further showed that the imide oligomer composition G contained an imide oligomer of the above formula (4-1) (A is a group of the above formula (13) and B is a group of the above formula (14)) as the imide oligomer having a structure of the formula (1-1).

SYNTHESIS EXAMPLE 8

Preparation of Imide Oligomer Composition H

(27) An imide oligomer composition H (imidization ratio: 91%) was obtained as in Synthesis Example 4 except that the amount of 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride added was changed to 78.1 parts by weight.

(28) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition H contained an imide oligomer having a structure of the above formula (1-1) (A is a group of the above formula (17) and B is a group of the above formula (14)). The imide oligomer having a structure of the formula (1-1) had a number average molecular weight of 4,200.

SYNTHESIS EXAMPLE 9

Preparation of Imide Oligomer Composition I

(29) An imide oligomer composition I (imidization ratio: 90%) was obtained as in Synthesis Example 1 except that 62.0 parts by weight of 3,4′-oxydiphthalic dianhydride was changed to 52.0 parts by weight of 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride (available from Tokyo Chemical Industry Co., Ltd.), and that 34.5 parts by weight of 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene was changed to 12.4 parts by weight of 1,3-bis(3-aminopropyl)tetramethyldisiloxane (available from Tokyo Chemical Industry Co., Ltd.).

(30) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition I contained an imide oligomer having a siloxane skeleton and an acid anhydride group at an end. The imide oligomer had a number average molecular weight of 1,880.

Synthesis Example 10

Preparation of Imide Oligomer Composition J

(31) An amount of 24.6 parts by weight of 5-amino-o-cresol was dissolved in 400 parts by weight of N-methylpyrrolidone (available from Wako Pure Chemical Industries, Ltd., “NMP”). To the obtained solution was added 31.0 parts by weight of 3,4′-oxydiphthalic dianhydride (available from Tokyo Chemical Industry Co., Ltd., “3,4′-ODPA”), followed by stirring at 25° C. for two hours to cause reaction to give an amic acid oligomer solution. N-Methylpyrrolidone was removed from the obtained amic acid oligomer solution under reduced pressure, followed by heating at 300° C. for two hours to give an imide oligomer composition J (imidization ratio: 91%).

(32) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition J contained an imide oligomer having a structure of the above formula (1-2) (A is a group of the above formula (13) and Ar is a group of the following formula (18)). The imide oligomer having a structure of the formula (1-2) had a number average molecular weight of 650. The analyses further showed that the imide oligomer composition J contained an imide oligomer of the above formula (5-1) (A is a group of the above formula (13) and R is a methyl group) as the imide oligomer having a structure of the formula (1-2).

(33) ##STR00018##

(34) In the formula (18), * and ** are each a binding site, and * is a binding site to the hydroxy group in the formula (1-2).

SYNTHESIS EXAMPLE 11

Preparation of Imide Oligomer Composition K

(35) An imide oligomer composition K (imidization ratio: 90%) was obtained as in Synthesis Example 10 except that 24.6 parts by weight of 5-amino-o-cresol was changed to 21.8 parts by weight of 3-aminophenol.

(36) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition K contained an imide oligomer having a structure of the above formula (1-2) (A is a group of the above formula (13) and Ar is a group of the following formula (19)). The imide oligomer having a structure of the formula (1-2) had a number average molecular weight of 630. The analyses further showed that the imide oligomer composition K contained an imide oligomer of the above formula (5-1) (A is a group of the above formula (13) and R is a hydrogen atom) as the imide oligomer having a structure of the formula (1-2).

(37) ##STR00019##

(38) In the formula (19), * is a binding site.

SYNTHESIS EXAMPLE 12

Peparation of Imide Oligomer Composition L

(39) An imide oligomer composition L (imidization ratio: 92%) was obtained as in Synthesis Example 10 except that 31.0 parts by weight of 3,4′-oxydiphthalic dianhydride was changed to 52.0 parts by weight of 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride.

(40) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition L contained an imide oligomer having a structure of the above formula (1-2) (A is a group of the above formula (17) and Ar is a group of the above formula (18)). The imide oligomer having a structure of the formula (1-2) had a number average molecular weight of 910. The analyses further showed that the imide oligomer composition L contained an imide oligomer of the above formula (5-1) (A is a group of the above formula (17) and R is a methyl group) as the imide oligomer having a structure of the formula (1-2).

SYNTHESIS EXAMPLE 13

Preparation of Imide Oligomer Composition M

(41) An imide oligomer composition M (imidization ratio: 91%) was obtained as in Synthesis Example 10 except that 31.0 parts by weight of 3,4′-oxydiphthalic dianhydride was changed to 135.0 parts by weight of the imide oligomer composition E obtained in Synthesis Example 5.

(42) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition M contained an imide oligomer having a structure of the above formula (1-2) (A is a group of the above formula (17) and Ar is a group of the above formula (18). The imide oligomer having a structure of the formula (1-2) had a number average molecular weight of 2,960. The analyses further showed that the imide oligomer composition M contained an imide oligomer of the above formula (5-3) (A is a group of the above formula (17), B is a group of the above formula (14), and R is a methyl group) as the imide oligomer having a structure of the formula (1-2).

SYNTHESIS EXAMPLE 14

Preparation of Imide Oligomer Composition N

(43) An imide oligomer composition N (imidization ratio: 91%) was obtained as in Synthesis Example 10 except that the amount of 5-amino-o-cresol added was changed to 25.9 parts by weight.

(44) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition N contained an imide oligomer having a structure of the above formula (1-2) (A is a group of the above formula (13) and Ar is a group of the above formula (18)). The imide oligomer having a structure of the formula (1-2) had a number average molecular weight of 590. The analyses further showed that the imide oligomer composition N contained an imide oligomer of the above formula (5-1) (A is a group of the above formula (13) and R is a methyl group) as the imide oligomer having a structure of the formula (1-2).

SYNTHESIS EXAMPLE 15

Preparation of Imide Oligomer Composition O

(45) An amount of 24.6 parts by weight of 5-amino-o-cresol was dissolved in 400 parts by weight of N-methylpyrrolidone (available from Wako Pure Chemical Industries, Ltd., “NMP”). To the obtained solution was added 31.0 parts by weight of 3,4′-oxydiphthalic dianhydride (available from Tokyo Chemical Industry Co., Ltd., “3,4′-ODPA”), followed by stirring at 25° C. for two hours to cause reaction to give an amic acid oligomer solution. The amic acid oligomer solution was heated at 180° C. for three hours in N-methylpyrrolidone while removing with a Dean-Stark tube the water generated from imidization, and then N-methylpyrrolidone was removed under reduced pressure. Thus, an imide oligomer composition 0 (imidization ratio: 25%) was obtained.

(46) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition 0 contained an imide oligomer having a structure of the above formula (1-2) (A is a group of the above formula (13) and Ar is a group of the above formula (18)). The imide oligomer having a structure of the formula (1-2) had a number average molecular weight of 680. The analyses further showed that the imide oligomer composition 0 contained an imide oligomer of the above formula (5-1) (A is a group of the above formula (13) and R is a methyl group) as the imide oligomer having a structure of the formula (1-2).

SYNTHESIS EXAMPLE 16

Preparation of Imide Oligomer Composition P

(47) An imide oligomer composition P (imidization ratio:

(48) 90%) was obtained as in Synthesis Example 10 except that 31.0 parts by weight of 3,4′-oxydiphthalic dianhydride was changed to 180.0 parts by weight of the imide oligomer composition H obtained in Synthesis Example 8.

(49) .sup.1H-NMR, GPC, and FT-IR analyses showed that the imide oligomer composition P contained an imide oligomer having a structure of the above formula (1-2) (A is a group of the above formula (17) and Ar is a group of the above formula (18)). The imide oligomer having a structure of the formula (1-2) had a number average molecular weight of 4,610.

(50) (Solubility)

(51) Each of the imide oligomer compositions obtained in the synthesis examples was dissolved in methyl ethyl ketone (MEK), tetrahydrofuran (THF), and a bisphenol F epoxy resin (available from DIC Corporation, “EPICLON EXA-830CRP”). The solubility was evaluated as “Good (o)” when the amount of the imide oligomer composition dissolved in the MEK, THF, and bisphenol F epoxy resin, 10 g each, was 3 g or more, “Fair (Δ)” when the amount was 1 g or more and less than 3 g, and “Poor (×)” when the amount was less than 1 g.

(52) For the MEK and THF, a predetermined amount of the imide oligomer composition was added to 10 g of the MEK or THF, followed by stirring using a planetary stirrer. The solubility at 25° C. was then evaluated. For EXA-830CRP, a predetermined amount of the imide oligomer composition was added to 10 g of EXA-830CRP, followed by stirring for one hour with heating at 150° C., then followed by cooling. The solubility at 25° C. was then evaluated.

(53) Table 1 shows the results.

(54) (Melting Point)

(55) The melting point of each of the imide oligomer compositions obtained in the synthesis examples was measured as the endothermic peak temperature using a differential scanning calorimeter (EXTEAR DSC6100 (available from SII NanoTechnology Inc.) at a temperature increase rate of 10° C./min.

(56) Table 1 shows the results.

(57) TABLE-US-00001 TABLE 1 Imide oligomer composition A B C D E F G H I Solubility MEK ∘ ∘ Δ ∘ Δ ∘ ∘ x ∘ (Boiling point 80° C.) THF ∘ ∘ ∘ ∘ ∘ ∘ ∘ Δ ∘ (Boiling point 66° C.) EXA-830CRP ∘ ∘ ∘ ∘ ∘ ∘ ∘ x Δ Melting point (° C.) 157 167 140 138 138 152 147 143 58 Imide oligomer composition J K L M N O P Solubility MEK ∘ ∘ ∘ Δ ∘ ∘ x (Boiling point 80° C.) THF ∘ ∘ ∘ ∘ ∘ ∘ x (Boiling point 66° C.) EXA-830CRP ∘ ∘ ∘ Δ ∘ ∘ x Melting point (° C.) 160 149 140 183 155 150 193

EXAMPLES 1 to 16 AND COMPARATIVE EXAMPLES 1 to 5

(58) Curable resin compositions of Examples 1 to 16 and Comparative Examples 1 to 5 were prepared by mixing materials according to the formulations shown in Tables 2 to 5.

(59) Each obtained curable resin composition was applied to a substrate PET film to a thickness of about 20 μm and dried to give a curable resin composition film.

(60) The PET film was removed from the obtained curable resin composition film. Polyimide films (available from Du Pont-Toray Co., Ltd., “Kapton 200H”) each having a thickness of 50 μm were bonded to both surfaces of the adhesive layer using a laminator with heating at 80° C. The laminate was hot pressed under the conditions of 190° C., 3 MPa, and one hour to cure the adhesive layer, and then cut to a specimen having a width of 1 cm. The initial adhesive force of the specimen within 24 hours after the preparation was measured by a T-peel test at 25° C. at a peeling speed of 20 mm/min using a tensile tester (available from Orientec Co., Ltd., “UCT-500”). Separately, a specimen prepared in the same manner was stored at 200° C. for 100 hours and then cooled to 25° C. The adhesive force of the specimen within 24 hours after the cooling was measured in the same method as the initial adhesive force.

(61) Furthermore, a specimen prepared in the same manner was stored in an environment at 85° C. and 85% RH for 24 hours and then cooled to 25° C. The adhesive force of the specimen within 24 hours after the cooling was measured in the same method as the initial adhesive force.

(62) The tack value at 25° C. and the tack value at 60° C. of each curable resin composition film were measured at the side opposite to the substrate film side. The tack values were measured with a probe tack measuring device (Tackiness Tester TAC-2 (available from RHESCA Co., LTD.)) under the measurement conditions of a probe diameter of 5 mm, a contact speed of 0.5 mm/sec, a test speed of 0.5 mm/sec, a contact load of 0.05 MPa, a contact time of 1 second, and a measurement temperature of 25° C. and 60° C.

(63) The surface free energy of each obtained curable resin composition film was measured using the side opposite to the substrate film side. The surface free energy was calculated by the above formulae based on the measurement of the contact angle (drop volume: 3 μL, 30 seconds after dropping) with water and methylene iodide using a contact angle meter.

(64) Tables 2 to 5 show the obtained measurement results of the initial adhesive force, the adhesive force after storage at 200° C. for 100 hours, the adhesive force after storage at 85° C. and 85% RH for 24 hours, the tack value at 25° C., the tack value at 60° C., and the surface free energy.

(65) <Evaluation>

(66) The curable resin compositions obtained in the examples and the comparative examples were evaluated as follows. Tables 2 to 5 show the results.

(67) (Weight Reduction Ratio at 330° C.)

(68) Each of the curable resin compositions obtained in the examples and the comparative examples was applied to a substrate film and dried to give a curable resin composition film.

(69) The weight reduction ratio (%) at 330° C. of the curable resin composition film was measured using a device for thermogravimetry (available from SII NanoTechnology Inc., “EXTEAR TG/DTA6200”) by increasing the temperature from 30° C. to 400° C. at 10° C./min.

(70) (Glass Transition Temperature)

(71) Each of the curable resin compositions obtained in the examples and the comparative examples was applied to a substrate film and dried to give a curable resin composition film. Curable resin composition films obtained in this manner were stacked and heated at 190° C. for 30 minutes to be cured, whereby a cured product having a thickness of 400 μm was obtained. The glass transition temperature of the obtained cured product was determined as the peak temperature on a tan δ curve obtained when the temperature was increased from 0° C. to 300° C. using a dynamic viscoelasticity measuring apparatus (available from A & D Company, Limited, “RHEOVIBRON DDV-25GP”) at a temperature increase rate of 10° C./min, a frequency of 10 Hz, and a chuck interval of 24 mm. A glass transition temperature of 150° C. or higher was evaluated as “Good (o)”. A glass transition temperature of 130° C. or higher and lower than 150° C. was evaluated as “Fair (Δ)”. A glass transition temperature of lower than 130° C. was evaluated as “Poor (×)”.

(72) (Long-Term Heat Resistance)

(73) Each of the curable resin compositions obtained in the examples and the comparative examples was applied to a substrate film and dried to give a curable resin composition film. Polyimide films (available from Du Pont-Toray Co., Ltd., “Kapton V”) each having a thickness of 20 μm were stacked on both surfaces of the obtained curable resin composition film (thickness: 20 μm) and heated at 190° C. for one hour to be cured, followed by heating at 175° C. for 1,000 hours. The laminate of the curable resin composition film and the polyimide films after the heat treatment was placed in an arch shape along a cylinder having a diameter of 5 mm or 3 mm at room temperature. The state of the laminate of the curable resin composition film and the polyimide films was then visually observed.

(74) The long-term heat resistance was evaluated as “Good (o)” in the case where no crack or fracture was observed at all when the laminate was placed in an arch shape along the cylinder having a diameter of 3 mm, “Fair (Δ)” in the case where no crack or fracture was observed when the laminate was placed in an arch shape along the cylinder having a diameter of 5 mm, but a crack or a fracture was observed when it was placed in an arch shape along the cylinder having a diameter of 3 mm, and “Poor (x)” in the case where a crack or fracture was observed when the laminate was placed in an arch shape along the cylinder having a diameter of 5 mm.

(75) TABLE-US-00002 TABLE 2 Examples 1 2 3 4 5 6 7 Composition Curable Bisphenol F epoxy resin 100 100 100 100 100 100 100 (parts by weight) resin (available from DIC Corporation, “EPICLON EXA-830CRP”, liquid at 25° C.) Curing Imide oligomer composition A 145 — — — — — — agent (imidizaion ratio 92%, containing an oligomer having a structure of formula (1-1) and a number average molecular weight of 1380) Imide oligomer composition B — 145 — — — — — (imidizaion ratio 92%, containing an oligomer having a structure of formula (1-1) and a number average molecular weight of 1390) Imide oligomer composition C — — 137 — — — — (imidizaion ratio 91%, containing an oligomer having a structure of formula (1-1) and a number average molecular weight of 1310) Imide oligomer composition D — — — 211 — — — (imidizaion ratio 93%, containing an oligomer having a structure of formula (1-1) and a number average molecular weight of 2020) Imide oligomer composition E — — — — 222 — — (imidizaion ratio 91%, containing an oligomer having a structure of formula (1-1) and a number average molecular weight of 2520) Imide oligomer composition F — — — — — 132 — (imidizaion ratio 92%, containing an oligomer having a structure of formula (1-1) and a number average molecular weight of 1220) Imide oligomer composition G — — — — — — 145 (imidizaion ratio 23%, containing an oligomer having a structure of formula (1-1) and a number average molecular weight of 1400) Curing 2,4-Diamino-6-(2′-methylimidazolyl- 5 5 5 5 5 5 5 accelerator (1′))-ethyl-s-triazine (available from Shikoku Chemicals Corporation, “2MZ-A”, melting point 248° C. to 258° C.) Organic Polyimide particles — — — — — — — filler (available from Ube Industries, Ltd., “UIP-S”) Fluidity Hydrophobic fumed silica 5 5 5 5 5 5 5 modifier (available from Tokuyama Corporation, “MT-10”) Solvent Methyl ethyl ketone 300 300 300 300 300 300 300 (available from Wako Pure Chemical Industries, Ltd., “MEK”) Initial adhesive force (N/cm) 8.6 9.5 9.8 7.8 8.6 9.0 5.5 Adhesive force (N/cm) after storage at 7.2 9.0 8.6 7.0 8.3 8.6 4.5 200° C. for 100 hours (Adhesive force after storage at 200° C. 0.84 0.95 0.88 0.90 0.97 0.96 0.82 for 100 hours)/(Initial adhesive force) Adhesive force (N/cm) after storage at 8.4 9.0 9.2 7.7 8.5 8.4 4.4 85° C. and 85% RH for 24 hours (Adhesive force after storage at 85° C. and 0.98 0.95 0.94 0.99 0.99 0.93 0.80 85% RH for 24 hours)/(Initial adhesive force) Tack value at 25° C. (gf/5 mmφ) 7.8 5.4 8.6 9.2 3.8 6.8 10.5 Tack value at 60° C. (gf/5 mmφ) 35.8 19.2 23.4 23 12.7 15.2 25.6 (Tack value at 60° C.)/(Tack value at 25° C.) 4.6 3.6 2.7 2.5 3.3 2.2 2.4 Surcace free energy (mJ/m.sup.2) 47.3 50.5 47.9 46.5 41.5 42.1 54.5 Evaluation Weight reduction ratio at 330° C. (%) 1.4 1.4 1.5 1.2 1.4 1.5 2.0 Glass transition temperature ∘ ∘ ∘ ∘ ∘ ∘ ∘ Long-term heat resistance (175° C., 1000 hours) ∘ ∘ ∘ ∘ ∘ ∘ Δ

(76) TABLE-US-00003 TABLE 3 Examples 8 9 10 11 12 13 Composition Curable resin Bisphenol F epoxy resin 100 100 100 100 100 100 (parts by weight) (available from DIC Corporation, “EPICLON EXA-830CRP”, liquid at 25° C.) Curing agent Imide oligomer composition J 163 — — — — — (imidizaion ratio 91%, containing an oligomer having a structure of formula (1-2) and a number average molecular weight of 650) Imide oligomer composition K — 154 — — — — (imidizaion ratio 90%, containing an oligomer having a structure of formula (1-2) and a number average molecular weight of 630) Imide oligomer composition L — — 228 — — — (imidizaion ratio 92%, containing an oligomer having a structure of formula (1-2) and a number average molecular weight of 910) Imide oligomer composition M — — — 487 — — (imidizaion ratio 91%, containing an oligomer having a structure of formula (1-2) and a number average molecular weight of 2960) Imide oligomer composition N — — — — 148 — (imidizaion ratio 91%, containing an oligomer having a structure of formula (1-2) and a number average molecular weight of 590) Imide oligomer composition O — — — — — 163 (imidizaion ratio 25%, containing an oligomer having a structure of formula (1-2) and a number average molecular weight of 680) Curing 2,4-Diamino-6-(2′-methylimidazolyl- 5 5 5 5 5 5 accelerator (1′))-ethyl-s-triazine (available from Shikoku Chemicals Corporation, “2MZ-A”, melting point 248° C. to 258° C.) Organic filler Polyimide particles — — — — — — (available from Ube Industries, Ltd., “UIP-S”) Fluidity Hydrophobic fumed silica 5 5 5 5 5 5 modifier (available from Tokuyama Corporation, “MT-10”) Solvent Methyl ethyl ketone 300 300 300 300 300 300 (available from Wako Pure Chemical Industries, Ltd., “MEK”) Initial adhesive force (N/cm) 5.0 5.9 4.9 6.5 5.8 4.0 Adhesive force (N/cm) after storage at 4.8 5.1 4.6 5.4 5.0 3.3 200° C. for 100 hours (Adhesive force after storage at 200° C. 0.96 0.86 0.94 0.83 0.86 0.83 for 100 hours)/(Initial adhesive force) Adhesive force (N/cm) after storage at 4.5 5.4 4.5 6.4 5.0 3.3 85° C. and 85% RH for 24 hours (Adhesive force after storage at 85° C. 0.90 0.92 0.92 0.98 0.86 0.83 and 85% RH for 24 hours)/(Initial adhesive force) Tack value at 25° C. (gf/5 mmφ) 6.9 7.6 8.5 4.5 5.9 9.5 Tack value at 60° C. (gf/5 mmφ) 28.2 26.8 21.6 12.4 31.5 19.5 (Tack value at 60° C.)/(Tack value at 25° C.) 4.1 3.5 2.5 2.8 5.3 2.1 Surcace free energy (mJ/m.sup.2) 46.5 42.5 47.8 48.5 45.0 52.0 Evaluation Weight reduction ratio at 330° C. (%) 1.5 1.6 1.4 1.9 1.6 2.0 Glass transition temperature ∘ ∘ ∘ ∘ ∘ ∘ Long-term heat resistance (175° C., 1000 hours) ∘ ∘ ∘ Δ ∘ Δ

(77) TABLE-US-00004 TABLE 4 Examples 14 15 16 Composition Curable resin Bisphenol A epoxy resin 100 — — (parts by (available from DIC Corporation, weight) “EPICLON EXA-850CRP”, liquid at 25° C.) Resorcinol epoxy resin — 100 — (available from Nagase ChemteX Corporation, “DENACOL EX-201P”, liquid at 25° C.) Phenol novolac epoxy resin — — 100 (available from The Dow Chemical Company, “D.E.N. 431”, semisolid at 25° C.) Curing agent Imide oligomer composition A 136 232 133 (imidizaion ratio 92%, containing an oligomer having a structure of formula (1-1) and a number average molecular weight of 1380) Curing 2,4-Diamino-6-(2′-methylimidazolyl- 5 5 5 accelerator (1′))-ethyl-s-triazine (available from Shikoku Chemicals Corporation, “2MZ-A”, melting point 248° C. to 258° C.) Organic filler Polyimide particles — — — (available from Ube Industries, Ltd., “UIP-S”) Fluidity Hydrophobic fumed silica 5 5 5 modifier (available from Tokuyama Corporation, “MT-10”) Solvent Methyl ethyl ketone 300 300 300 (available from Wako Pure Chemical Industries, Ltd., “MEK”) Initial adhesive force (N/cm) 8.5 7.9 7.0 Adhesive force (N/cm) after storage 7.7 7.6 6.8 at 200° C. for 100 hours (Adhesive force after storage at 200° C. 0.91 0.96 0.97 for 100 hours)/(Initial adhesive force) Adhesive force (N/cm) after storage at 8.4 7.4 6.5 85° C. and 85% RH for 24 hours (Adhesive force after storage at 85° C. 0.99 0.94 0.93 and 85% RH for 24 hours)/(Initial adhesive force) Tack value at 25° C. (gf/5 mmφ) 6.8 8.6 2.5 Tack value at 60° C. (gf/5 mmφ) 46.5 28.5 19.2 (Tack value at 60° C.)/(Tack value at 25° C.) 6.8 3.3 7.7 Surcace free energy (mJ/m.sup.2) 47.2 48.6 45.7 Evaluation Weight reduction ratio at 330° C. (%) 1.4 1.3 1.4 Glass transition temperature ∘ ∘ ∘ Long-term heat resistance (175° C., 1000 hours) ∘ ∘ ∘

(78) TABLE-US-00005 TABLE 5 Comparative Examples 1 2 3 4 5 Composition Curable Bisphenol F epoxy resin 100 100 100 100 100 (parts by resin (available from DIC Corporation, weight) “EPICLON EXA-830CRP”) Curing Imide oligomer composition H 281 — — — — agent (imidizaion ratio 91%, containing an oligomer having a structure of formula (1-1) and a number average molecular weight of 4200) Imide oligomer composition P — 649 — — — (imidizaion ratio 90%, containing an oligomer having a structure of formula (1-2) and a number average molecular weight of 4610) Imide oligomer composition I — — 157 — — (imidization ratio 90%, containing an oligomer having a siloxane skeleton and a number average molecular weight of 1880) Trialkyltetrahydrophthalic anhydride — — — 73 — (available from Mitsubishi Chemical Corporation, “YH-306”) Diallylbisphenol A — — — — 87 (available from Meiwa Plastic Industries, Ltd., “MEH-8000H”) Curing 2,4-Diamino-6-(2′-methylimidazolyl- 5 5 5 5 5 accelerator (1′))-ethyl-s-triazine (available from Shikoku Chemicals Corporation, “2MZ-A”, melting point 248° C. to 258° C.) Organic Polyimide particles — — — — — filler (available from Ube Industries, Ltd., “UIP-S”) Fluidity Hydrophobic fumed silica 5 5 5 5 5 modifier (available from Tokuyama Corporation, “MT-10”) Solvent Methyl ethyl ketone 300 300 300 300 300 (available from Wako Pure Chemical Industries, Ltd., “MEK”) Initial adhesive force (N/cm) 3.0 3.3 6.7 6.5 6 Adhesive force (N/cm) after storage at 2.5 2.0 2.8 4.2 1.5 200° C. for 100 hours (Adhesive force after storage at 200° C. 0.83 0.61 0.42 0.65 0.25 for 100 hours)/(Initial adhesive force) Adhesive force (N/cm) after storage at 2.5 2.8 6.0 2.5 1 85° C. and 85% RH for 24 hours (Adhesive force after storage at 85° C. 0.83 0.85 0.90 0.38 0.17 and 85% RH for 24 hours)/(Initial adhesive force) Tack value at 25° C. (gf/5 mmφ) 5.5 4.9 3.5 13.5 31.5 Tack value at 60° C. (gf/5 mmφ) 8.5 6.7 7.0 26.8 40.8 (Tack value at 60° C.)/(Tack value at 25° C.) 1.5 1.4 2.0 2.0 1.3 Surcace free energy (mJ/m.sup.2) 45.5 41.9 34.5 40.6 34.0 Evaluation Weight reduction ratio at 330° C. (%) 2.5 2.8 1.7 3.0 1.5 Glass transition temperature ∘ ∘ x ∘ x Long-term heat resistance (175° C., 1000 hours) x x x x x

INDUSTRIAL APPLICABILITY

(79) The present invention can provide a curable resin composition capable of providing a cured product that has a high glass transition temperature after curing and is excellent in thermal decomposition resistance, adhesiveness, and long-term heat resistance. The present invention also can provide a cured product of the curable resin composition, an adhesive containing the curable resin composition, and an adhesive film, a coverlay film, a flexible copper clad laminate, and a circuit board each formed using the curable resin composition.