Thermosetting resin composition of semi-IPN composite, and varnish, prepreg and metal clad laminated board using the same

1. A process for manufacturing a thermosetting resin composition comprising a polyphenylene ether-modified butadiene prepolymer that includes a polyphenylene ether (A) and a butadiene polymer, wherein:

the butadiene polymer has a crosslinking structure;

the process has a step (1) in which a butadiene polymer (B) crosslinks with a crosslinking agent (C) (excluding the butadiene polymer (B)) in the presence of the polyphenylene ether (A) in a medium to obtain the polyphenylene ether-modified butadiene prepolymer;

the number average molecular weight of the polyphenylene ether (A) is in a range of 7,000 to 30,000;

the butadiene polymer (B) molecule contains 40% or more of a 1,2-butadiene unit having a 1,2-vinyl group in a side chain;

the butadiene polymer (B) is not a modified polybutadiene in which the 1,2-vinyl group in the side chain, or one or both of the terminals in the molecule is/are chemically modified by converting into epoxy, glycol, phenol, maleic acid, (meth)acryl, or urethane; and

the crosslinking agent (C) is at least one maleimide compound including 2,2-bis (4-(4-maleimidophenoxy)phenyl)propane, or the crosslinking agent (C) is at least one maleimide compound including bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, and

with the proviso that the polyphenylene ether (A) which is a modified phenol product so preferred by redistribution reaction of a polyphenylene ether resin having a number average molecular weight of 10,000-30,000 with a phenolic compound in the presence of a reaction initiator that the number average molecular weight of the product becomes 5 to 70% of that of the used polyphenylene ether resin is excluded.

2. The process according to claim 1 , wherein

the butadiene polymer (B) comprises

(j) a —[CH 2 —CH═CH—CH 2 ]— unit and

(k) a —[CH 2 —CH(CH═CH 2 )]— unit, with a ratio of j:k being 60 to 5:40 to 95; and

the crosslinking agent (C) is a compound having one or more ethylenically unsaturated double bonds in a molecule.

3. The process according to claim 1 , wherein

the crosslinking agent (C) contains at least one maleimide compound represented by the formula (1):

wherein R 1 is an aliphatic or aromatic organic group having a valence of m; Xa and Xb, which may be identical or different from each other, are each a monovalent atom or an organic group, selected from hydrogen atom, a halogen atom and an aliphatic organic group; and m represents an integer of 1 or greater.

4. The thermosetting resin composition according to claim 1 , wherein the crosslinking agent (C) is at least one maleimide compound including 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane.

5. The process according to claim 1 , wherein the crosslinking agent (C) is at least one maleimide compound including bis(3-ethyl-5-methyl-4-maleimidophenyl)methane.

6. The process according to claim 1 , wherein a mixing proportion of the polyphenylene ether (A) is in a range of 2 to 200 parts by weight based on 100 parts by weight of the total amount of the butadiene polymer (B) and the crosslinking agent (C), and a mixing proportion of the crosslinking agent (C) is in a range of 2 to 200 parts by weight based on 100 parts by weight of the butadiene polymer (B).

7. The process according to claim 1 , wherein a conversion rate of the crosslinking agent (C) falls in the range of 5 to 100% in the step (1).

8. The process according to claim 1 , wherein the butadiene polymer (B) crosslinks with the crosslinking agent (C) further in the presence of a radical reaction initiator (D) in the step (1).

9. The process according to claim 1 , wherein the process further comprises a step (2) in which the polyphenylene ether-modified butadiene prepolymer obtained in the step (1) and a radical reaction initiator (D) are incorporated.

10. The process according to claim 9 , wherein a compound (E) of a crosslinkable monomer or crosslinkable polymer which does not constitute the uncured semi-IPN composite, and contains one or more groups having an ethylenically unsaturated double bond in a molecule, is further incorporated in the step (2).

11. The process according to claim 10 , wherein the compound (E) is at least one crosslinkable monomer or crosslinkable polymer containing a group having an ethylenically unsaturated double bond, selected from the group consisting of chemically unmodified butadiene polymers, maleimide compounds and styrene-butadiene copolymers.

12. The process according to claim 10 , wherein a compound (F) of at least one of a bromine-based flame retardant and a phosphorus-based flame retardant is further incorporated in the step (2).

13. The process according to claim 10 , wherein an inorganic filler (G) is further incorporated in the step (2).

14. A process for manufacturing a resin varnish for printed circuit boards, which comprises:

performing the process for manufacturing a thermosetting resin composition according to claim 1 ; and

dissolving or dispersing the thermosetting resin composition in a solvent.

15. A process for manufacturing a prepreg, which comprises:

performing the process for manufacturing a resin varnish for printed circuit boards according to claim 14 ; and

impregnating the resin varnish for printed circuit boards into a substrate, and then drying.

16. A process for manufacturing a prepreg, which comprises:

performing the process for manufacturing a prepreg according to claim 15 ; and

stacking one or more sheets of the prepreg for printed circuit boards, so as to form a stacked prepreg;

disposing metal foil on one side or both sides of the stacked prepreg; and

pressing the sheets with the metal foil together while heating.

17. A process for manufacturing a resin varnish for printed circuit boards, which comprises:

performing the process for manufacturing a thermosetting resin composition according to claim 9 ; and

dissolving or dispersing the thermosetting resin composition in a solvent.

18. A process for manufacturing a prepreg, which comprises:

performing the process for manufacturing a resin varnish for printed circuit boards according to claim 17 ; and

impregnating the resin varnish for printed circuit boards into a substrate, and then drying.

19. A process for manufacturing a prepreg, which comprises:

performing the process for manufacturing a prepreg according to claim 18 ; and

stacking one or more sheets of the prepreg for printed circuit boards, so as to form stacked prepreg;

disposing metal foil on one side or both sides of the stacked prepreg; and

pressing the sheets with the metal foil together while heating.

20. A process for manufacturing a resin varnish for printed circuit boards, which comprises:

performing the process for manufacturing a thermosetting resin composition according to claim 10 ; and

dissolving or dispersing the thermosetting resin composition in a solvent.

21. A process for manufacturing a prepreg, which comprises:

performing the process for manufacturing a resin varnish for printed circuit boards according to claim 20 ; and

impregnating the resin varnish for printed circuit boards into a substrate, and then drying.

22. A process for manufacturing a prepreg, which comprises:

performing the process for manufacturing a prepreg according to claim 21 ; and

stacking one or more sheets of the prepreg for printed circuit boards, so as to form stacked prepreg;

disposing metal foil on one side or both sides of the stacked prepreg; and

pressing the sheets with the metal foil together while heating.

23. A process for manufacturing a resin varnish for printed circuit boards, which comprises:

performing the process for manufacturing a thermosetting resin composition according to claim 8 ; and

dissolving or dispersing the thermosetting resin composition in a solvent.

24. A process for manufacturing a prepreg, which comprises:

performing the process for manufacturing a resin varnish for printed circuit boards according to claim 23 ; and

impregnating the resin varnish for printed circuit boards into a substrate, and then drying.

25. A process for manufacturing a prepreg, which comprises:

performing the process for manufacturing a prepreg according to claim 24 ; and

stacking one or more sheets of the prepreg for printed circuit boards, so as to form a stacked prepreg;

disposing metal foil on one side or both sides of the stacked prepreg; and

pressing the sheets with the metal foil together while heating.