Resin composition comprising coated metal oxide particles, resin-attached metal foil, metal-clad laminated sheet, and capacitor element

1. A resin composition comprising:

coated particles, each comprising a core containing a metal oxide and a coating layer containing an aluminum hydrous oxide and provided on a surface of the core; and

a resin,

wherein the metal oxide is represented by MxOy, where M represents at least one element selected from the group consisting of Ba, Ti, Sr, Pb, Zr, La, Ta, Ca, and Bi, and x and y each represent a number determined from a stoichiometric ratio according to the valence of the metal element M,

the resin composition has an atomic ratio Al/(M+Al) of 0.05 or more and 0.7 or less, as determined by XPS for the particles contained in the resin composition, and

a proportion of an aluminum element is 0.2 mass % or more and 3.0 mass % or less, based on the mass of all particles contained in the resin composition.

2. The resin composition according to claim 1 ,

wherein the coated particles have a 50th percentile particle size D 50 of 0.01 μm or more and 3.0 μm or less in a volume-weighted particle size distribution as determined by a laser diffraction/scattering method.

3. The resin composition according to claim 1 ,

wherein the element M at least contains Ti and at least one of Ba and Sr.

4. The resin composition according to claim 1 ,

wherein the metal oxide is a compound having a perovskite crystal structure.

5. The resin composition according to claim 1 , further comprising particles made of the metal oxide but without the coating layer.

6. The resin composition according to claim 1 ,

wherein the coated particles are contained in an amount of 30 parts by mass or more and 90 parts by mass or less, per 100 parts by mass of the solid content of the resin composition.

7. The resin composition according to claim 1 ,

wherein the resin comprises at least one selected from the group consisting of an epoxy resin, a polyphenylene ether resin, an aromatic polyamide resin, a polyamide imide resin, a polyimide resin, an active ester resin, a phenol resin, and a diamine compound.

8. The resin composition according to claim 1 , further comprising barium sulfate particles.

9. The resin composition according to claim 1 ,

wherein the resin composition is in the form of a film with a thickness of 15 μm or less.

10. A resin-coated metal foil comprising:

a metal foil; and

a layer made of the resin composition according to claim 1 and provided on at least one side of the metal foil.

11. The resin-coated metal foil according to claim 10 ,

wherein the metal foil is a copper foil.

12. A metal-clad laminate sheet comprising:

a first metal foil;

a second metal foil; and

a resin composition layer interposed between the two metal foils,

wherein the resin composition layer is a cured product of the resin composition according to claim 1 .

13. The metal-clad laminate sheet according to claim 12 ,

wherein the metal-clad laminate sheet exhibits a withstand voltage per unit thickness of the resin composition layer of 50 V/μm or more, as measured by applying a DC voltage between the two metal foils.

14. The metal-clad laminate sheet according to claim 12 ,

wherein the metal-clad laminate sheet exhibits a leakage current value of 150 uA/cm 2 or less, as measured by applying a DC voltage of 50 V between the two metal foils.

15. The metal-clad laminate sheet according to claim 12 ,

wherein the metal-clad laminate sheet has a peel strength of 0.3 kN/m or more between the metal foil and the resin composition layer.

16. A capacitor element comprising the metal-clad laminate sheet according to claim 12 .