Composite preform and method for producing the same, composite container and method for producing the same, and composite container product loaded with beer

A method for producing the composite preform, the method comprising the steps of:

• preparing a preform comprising a mouth part, a trunk part linked to the mouth part, and a bottom part linked to the trunk part, and a heat-contractive plastic member disposed to surround an outside of the preform and comprising at least a colored layer that contains a resin material and a colorant, the heat-contractive plastic member has a near-infrared transmittance of 50% or higher;
• fitting the preform into the heat-contractive plastic member from one end of the heat-contractive plastic member;
• thermocompression-bonding a margin part included in the heat-contractive plastic member, after the fitting step;
• and
• heating the preform and the heat-contractive plastic member to cause the heat-contractive plastic member to heat-contract.