Masaki Nakakado, Osaka, Japan.
Assigned to Zuiko Corporation, Osaka, Japan.

Filed: 7/25/13
Issued: 4/12/16

A method for manufacturing a composite sheet in which a plurality of granular particles are placed in a predetermined pattern between two sheets, wherein the method uses a first roll having a plurality of first depressions and protrusions on a circumferential surface of the first roll, and a second roll having a plurality of second depressions and protrusions on a circumferential surface of the second roll, the second depressions and protrusions fitting with the first depressions and protrusions, the method comprising: a step of carrying a first continuous sheet along a plurality of protruding portions of the second depressions and protrusions of the second roll so as to supply the first continuous sheet into between the first roll and the second roll; a step of causing some of the second depressions and protrusions of the second roll and some of the first depressions and protrusions of the first roll to rotate while fitting with each other, with the first continuous sheet interposed therebetween, thereby forming a plurality of third depressions and protrusions on the first continuous sheet; a placement step of placing the plurality of granular particles in depressed portions of the third depressions and protrusions; a step of laying a second continuous sheet on the first continuous sheet so as to cover openings of the depressed portions of the third depressions and protrusions and the granular particles, thereby forming a sandwich structure; and a bonding step of bonding the two sheets together along the protruding portions of the third depressions and protrusions, wherein a circumferential velocity V2 of the second roll is greater than a circumferential velocity V1 of the first roll.