Thermosetting resin composition, method for forming protective film for flexible wiring board, and flexible wiring board
A thermosetting resin composition which contains a polyurethane resin and a curing agent, the polyurethane resin including a constitutional unit derived from an alicyclic diol and having an acid value of 10 to 35 mgKOH/g.
1. A thermosetting resin composition comprising:
a polyurethane resin comprising a constitutional unit derived from an alicyclic diol in an amount of 0.1 to 30 mass % of the total mass polyurethane resin, the polyurethane resin having an acid value of 10 to 31 mgKOH/g; and
a curing agent comprising an epoxy resin,
wherein the polyurethane resin has been synthesized by:
reacting a diol including an alicyclic diol or a polycarbonatediol having a constitutional unit derived from an alicyclic diol with a polyisocyanate having an isocyanate group to obtain a polyisocyanate having a urethane linkage, and reacting the polyisocyanatel having the urethane linkage with an acid anhydride; or
reacting a diol including an alicyclic diol or a polycarbonatediol having a constitutional unit derived from an alicyclic diol and a dihydroxy compound having a carboxyl group with a polyisocyanate having an isocyanate group.
2. The thermosetting resin composition according to claim 1 , wherein the polyurethane resin has an amide linkage and/or an imide linkage.
3. The thermosetting resin composition according to claim 1 , wherein the polyurethane resin further comprises a constitutional unit derived from a polycarbonate diol represented by the following formula (2):
in the formula (2), R represents an alkylene group having 1 to 18 carbon atoms, and m represents an integer of 1 to 30.
4. A method for forming a protective film for a flexible wiring board, the method comprising the steps of:
printing the thermosetting resin composition according to claim 1 so as to cover at least a portion of a wiring pattern of the flexible wiring board, the wiring pattern being subjected to a Sn plating processing in advance; and
curing the printed thermosetting resin composition to form a protective film.
5. A flexible wiring board comprising a protective film formed by the method according to claim 4 .
6. A method for forming a protective film for a flexible wiring board, the method comprising the steps of:
printing the thermosetting resin composition according to claim 2 so as to cover at least a portion of a wiring pattern of the flexible wiring board, the wiring pattern being subjected to a Sn plating processing in advance; and
curing the printed thermosetting resin composition to form a protective film.
7. A flexible wiring board comprising a protective film formed by the method according to claim 6 .
8. A method for forming a protective film for a flexible wiring board, the method comprising the steps of:
printing the thermosetting resin composition according to claim 3 so as to cover at least a portion of a wiring pattern of the flexible wiring board, the wiring pattern being subjected to a Sn plating processing in advance; and
curing the printed thermosetting resin composition to form a protective film.
9. A flexible wiring board comprising a protective film formed by the method according to claim 8 .
10. The thermosetting resin composition according to claim 1 , wherein said constitutional unit derived from an alicyclic diol includes a constitutional unit derived from cyclohexanedimethanol.
11. The thermosetting resin composition according to claim 1 , wherein said constitutional unit derived from an alicyclic diol includes a constitutional unit derived from 1, 4-cyclohexanedimethanol.
12. The thermosetting resin composition according to claim 1 , wherein said constitutional unit derived from an alicyclic diol includes a constitutional unit derived from five-membered ring diols and six-membered ring diols.
13. The thermosetting resin composition according to claim 12 , wherein the polyurethane resin further comprises a constitutional unit derived from an aliphatic diol.
14. The thermosetting resin composition according to claim 2 , wherein the polyurethane resin has a carboxyl group or an acid anhydride group at an end of a molecule thereof.
15. The thermosetting resin composition according to claim 1 , said composition having a viscosity of 20 Pa·s to 80 Pa·s.
16. A cured product of the thermosetting resin composition according to claim 1 .
17. The thermosetting resin composition according to claim 1 , wherein the polyurethane resin has a number average molecular weight of 5000 to 65000.
18. The thermosetting resin composition according to claim 1 , wherein the alicyclic diol comprises at least one of 1,4-cyclohexane diol and 1,4-cyclohexane dimethanol.
19. The thermosetting resin composition according to claim 1 , wherein the polyurethane resin has been synthesized by:
reacting a diol including a polycarbonatediol having a constitutional unit derived from an alicyclic diol with a polyisocyanate having an isocyanate group to obtain a polyisocyanate having a urethane linkage, and reacting the polyisocyanate having the urethane linkage with an acid anhydride; or
reacting a diol including an alicyclic diol or a polycarbonatediol having a constitutional unit derived from an alicyclic diol and a dihydroxy compound having a carboxyl group with a polyisocyanate having an isocyanate group.
20. The thermosetting resin composition according to claim 1 , wherein the curing agent is included in an amount of 1 to 30 mass% of a total mass of the polyurethane resin.
21. The thermosetting resin composition according to claim 1 , wherein the polyurethane resin has been synthesized by reacting a diol including an alicyclic diol or a polycarbonatediol having a constitutional unit derived from an alicyclic diol with a polyisocyanate having an isocyanate group to obtain a polyisocyanate having a urethane linkage, and reacting the polyisocyanate having the urethane linkage with an acid anhydride.
22. The thermosetting resin composition according to claim 1 , wherein the polyisocyanate having an isocyanate group comprises a isocyanate compound represented by the following formula (4):
OCN—X—NCO (4)
wherein X represents a divalent organic group.
23. The thermosetting resin composition according to claim 1 , wherein the thermosetting resin composition comprises a property of providing a flexible copper-clad laminate plate having an MIT Flexibility-1 of 60 cycles or more, when the thermosetting resin is used to form a cured protective film having a thickness of 10 μm on the flexible copper-clad laminate plate comprising a polyimide film having a thickness of 38 μm, a comb-like copper foil wiring pattern having a thickness of 8 μm formed on the polyimide film, and a tin plating layer having a thickness of 0.2 to 0.3 μm formed on the copper foil.
24. The thermosetting resin composition according to claim 1 , wherein the polyurethane resin has an acid value of 10 to 28 mgKOH/g.