Can lid made of resin laminate steel sheet for resin-metal composite container, can bottom made of resin laminate steel sheet for resin-metal composite container, and resin-metal composite container

A can bottom made of a resin laminate steel sheet for a resin-metal composite container, comprising:

• a top sheet portion made of a resin laminate steel sheet;
• and
• a curved portion made of the resin laminate steel sheet and located at an outer periphery of the top sheet portion,
• wherein the resin laminate steel sheet includes
• a steel sheet,
• a thermoplastic polyester-based resin layer provided at a first surface of the steel sheet to be in contact with the steel sheet,
• a modified polypropylene-based resin layer provided at a second surface of the steel sheet to be in contact with the steel sheet,
• a polypropylene-based resin layer provided as an upper layer of the modified polypropylene-based resin layer to be in contact with the modified polypropylene-based resin layer, and
• an ethylene-propylene copolymer resin layer provided as an upper layer of the polypropylene-based resin layer to be in contact with the polypropylene-based resin layer and containing an ethylene-propylene copolymer including an ethylene component and a propylene component,
• a melting point of the ethylene-propylene copolymer resin layer is 135° C. or higher and 150° C. or lower,
• a melting point of the thermoplastic polyester-based resin layer is higher than a melting point of the polypropylene-based resin layer by 40° C. or more,
• a proportion of the ethylene component in the ethylene-propylene copolymer in the ethylene-propylene copolymer resin layer is 1.0 mass % or more and 45.0 mass % or less,
• an average thickness of the ethylene-propylene copolymer resin layer is 1.0 μm or more and 15.0 μm or less,
• an average thickness of the polypropylene-based resin layer is 6.0 μm or more,
• an average thickness of the modified polypropylene-based resin layer is 1.0 μm or more and 18.0 μm or less,
• a total average thickness of the ethylene-propylene copolymer resin layer, the polypropylene-based resin layer, and the modified polypropylene-based resin layer is 20.0 μm or more,
• the second surface is at an inside bend of the curved portion, and
• the first surface is at an outside bend of the curved portion.

A resin-metal composite container comprising:

• a can lid;
• a can body made of a polypropylene-based resin;
• a can bottom;
• a first seamed portion in which the can lid and the can body are seamed;
• and
• a second seamed portion in which the can bottom and the can body are seamed,
• wherein the first seamed portion has a first fused portion in which the can lid and the can body are fused,
• the second seamed portion has a second fused portion in which the can bottom and the can body are fused,
• at least one of the can lid or the can bottom includes
• a steel sheet,
• a thermoplastic polyester-based resin layer provided at a first surface of the steel sheet to be in contact with the steel sheet,
• a modified polypropylene-based resin layer provided at a second surface of the steel sheet to be in contact with the steel sheet,
• a polypropylene-based resin layer provided as an upper layer of the modified polypropylene-based resin layer to be in contact with the modified polypropylene-based resin layer, and
• an ethylene-propylene copolymer resin layer provided as an upper layer of the polypropylene-based resin layer to be in contact with the polypropylene-based resin layer and containing an ethylene-propylene copolymer including an ethylene component and a propylene component,
• a melting point of the ethylene-propylene copolymer resin layer is 135° C. or higher and 150° C. or lower,
• a melting point of the thermoplastic polyester-based resin layer is higher than a melting point of the polypropylene-based resin layer by 40° C. or more,
• a proportion of the ethylene component in the ethylene-propylene copolymer in the ethylene-propylene copolymer resin layer is 1.0 mass % or more and 45.0 mass % or less,
• an average thickness of the ethylene-propylene copolymer resin layer is 1.0 μm or more and 15.0 μm or less,
• an average thickness of the polypropylene-based resin layer is 6.0 μm or more,
• an average thickness of the modified polypropylene-based resin layer is 1.0 μm or more and 18.0 μm or less,
• a total average thickness of the ethylene-propylene copolymer resin layer, the polypropylene-based resin layer, and the modified polypropylene-based resin layer is 20.0 μm or more,
• the second surface is on a can body side, and
• the first surface is on a side opposite to the can body side.