Patent ID: 9283895
Filing Date: 2016-03-15
CPC Classification: B29C,B32B,B60R,E04C,Y10T

Claim Text:
1. A sandwich panel comprising two resin skin sheets, and a resin core material sandwiched between the two resin skin sheets and planarly adhered to each of the two resin skin sheets, wherein: said resin core material comprises a pair of foamed thermoplastic resin plates with a predetermined expansion ratio, each of the plates having a surface, a portion of which has a plurality of recesses and a portion of which has no recesses, the portion of the surface on which no recesses are formed defining a welding surface, each of the recesses protrudes inwardly in a truncated conical form in a thicknesswise direction from an opening in the surface of the plate to an opposite surface of the plate to define an annular rib surrounding a hollow inner space closed at the opening by the corresponding skin sheet, and each of said plurality of recesses inwardly tapers in a converging manner and is constituted by said annular rib protruding at its inner surface side, and a substantial thickness of the core material being constituted by a protruding height formed by each of all or part of the plurality of recesses on the surface of one of the plates abutting against the corresponding one of the plurality of recesses on the surface of the other of the plates, the rigidity of the resin skin sheets is set to be higher than that of the resin core material, each of said plurality of recesses includes an abutting portion at the most converged portion, whereby said core material is formed by welding the abutting portion of each of the plurality of recesses of one of the pair of the resin plates and that of the corresponding recess of the other of the pair of the resin plates, and the surface of each of said pair of the thermoplastic resin plates is joined to the corresponding skin sheet, the number and the annular shapes of said annular ribs are such that the planar adhesion of at least one surface of the resin core material to the corresponding skin sheet is maintained, while at the same time said annular ribs function to support a compressive load in the thickness direction of the resin core material, under the predetermined void volume allocated to said plurality of recesses in relation with said predetermined expansion ratio, and the relationship between the mean density (x) of said thermoplastic resin core material and the effective density (y) thereof meets the equation and the expansion ratio of said thermoplastic resin core material is less than, or equal to 10-fold.