Thermosetting resin composition, prepreg, resin sheet, metal foil-clad laminate, and printed wiring board

1. A thermosetting resin composition comprising

a thermosetting resin (A) containing a cyanate ester compound (D),

boron nitride (B), and

a dispersant (C) with a pH of 8 or higher, the dispersant (C) having a block chain (i) including a repeating unit represented by Formula [i]:

where, in Formula [i]:

R 101 represents a hydrogen atom or an alkyl group,

X 101 represents —NH— or —O—,

Y 101 represents a divalent linking group,

R 102 to R 104 each independently represent an alkyl group, an arylalkyl group, or a heteroarylalkyl group, and

Z − represents a counter anion;

wherein

the cyanate ester compound (D) contains one or more selected from the group consisting of:

a naphthol aralkyl cyanate ester compound represented by Formula (1):

where each R1 independently represents a hydrogen atom or a methyl group, and n1 represents an integer from 1 to 50,

a biphenyl aralkyl cyanate ester compound represented by Formula (2):

where each R3 independently represents a hydrogen atom or a methyl group, and n3 represents an integer from 1 to 50, and

a diallyl bisphenol A cyanate ester compound represented by Formula (3):

2. The thermosetting resin composition according to claim 1 , wherein the dispersant (C) further comprises a polymer including, as a monomer unit a tertiary amine compound containing a (meth)acryl group and/or a quaternary ammonium compound containing a (meth)acryl group.

3. The thermosetting resin composition according to claim 1 , wherein the dispersant (C) further comprises a block chain (ii) including a repeating unit represented by Formula [II]:

where, in Formula [II], R 201 represents a hydrogen atom or an alkyl group; X 201 represents —NH— or —O—; Y 201 represents a divalent linking group; R 202 and R 203 each independently represent an alkyl group, an arylalkyl group, or a heteroarylalkyl group.

4. The thermosetting resin composition according to claim 1 , wherein a content of the dispersant (C) is from 0.1 to 20 parts by mass relative to 100 parts by mass of resin solids.

5. The thermosetting resin composition according to claim 1 , wherein a weight average molecular weight of the dispersant (C) is 1.0×10 3 or higher and lower than 5.0×10 3 .

6. The thermosetting resin composition according to claim 1 , wherein the thermosetting resin (A) further comprises one or more selected from the group consisting of a maleimide compound (E), and an epoxy compound (F).

7. The resin composition according to claim 1 , wherein a content of the cyanate ester compound (D) is from 1 to 90 parts by mass relative to 100 parts by mass of resin solids.

8. The thermosetting resin composition according to claim 6 , wherein the maleimide compound (E) comprises one or more selected from the group consisting of bis(4-maleimidophenyl)methane, 2,2-bis{4-(4-maleimidophenoxy)-phenyl}propane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, a maleimide a maleimide compound represented by Formula (4), and a maleimide compound represented by Formula (5):

where, in Formula (4), R 5 each independently represents a hydrogen atom or a methyl group; and n 1 represents an integer of 1 or greater; and

where, in Formula (5), R's present in plurality each independently represents a hydrogen atom, an alkyl group having from 1 to 5 carbon atoms, or a phenyl group; and n is an average value and represents 1<n≤5.

9. The thermosetting resin composition according to claim 6 , wherein a content of the maleimide compound (E) is from 1 to 90 parts by mass relative to 100 parts by mass of resin solids.

10. The thermosetting resin composition according to claim 6 , wherein the epoxy compound (C) is one or more selected from the group consisting of a biphenyl aralkyl epoxy resin, naphthylene ether epoxy resin, trisphenol methane epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, bisphenol A novolac epoxy resin, brominated bisphenol A epoxy resin, brominated phenol novolac epoxy resin, biphenyl epoxy resin, phenol aralkyl epoxy resin, and naphthol aralkyl epoxy resin.

11. The thermosetting resin composition according to claim 6 , wherein the epoxy compound (F) includes a polyfunctional epoxy compound having three or more epoxy groups per molecule.

12. The thermosetting resin composition according to claim 6 , wherein a content of the epoxy compound (F) is from 1 to 90 parts by mass relative to 100 parts by mass of resin solids in the resin composition.

13. The thermosetting resin composition according to claim 1 , wherein a content of the boron nitride (B) is from 1 to 1600 parts by mass relative to 100 parts by mass of resin solids.

14. The thermosetting resin composition according to claim 1 , further comprising from 0.1 to 20 parts by mass of a silane coupling agent relative to 100 parts by mass of resin solids.

15. The thermosetting resin composition according to claim 1 , wherein the thermosetting resin composition is for a printed wiring board.

16. A prepreg having a substrate and the thermosetting resin composition described claim 1 , the substrate being impregnated or coated with the thermosetting resin composition.

17. A resin sheet having a support and the thermosetting resin composition described in claim 1 , the thermosetting resin composition being disposed on a surface of the support.

18. A metal foil-clad laminate having:

a laminate formed of one or more selected from the group consisting of the prepreg described in claim 16 and a resin sheet; and

a metal foil disposed on one or both sides of the laminate, wherein

the resin sheet has a support and the thermosetting resin composition is disposed on a surface of the support.

19. A printed wiring board having an insulating layer and a conductor layer formed on a surface of the insulating layer, wherein the insulating layer includes the thermosetting resin composition described in claim 1 .