Bottle-forming preform with a multilayered wall, and gaseous beverage bottle obtained with such a preform

Preform for forming a bottle for gaseous beverage, the preform comprising a preform multilayered wall obtained by injection in a mould from an injecting point located at a bottom end of the preform, the multilayered wall defining, from an open top end to a closed bottom end of the preform along a main axis of the preform:

• a neck finish portion,
• a body-forming portion configured to form a body portion of the bottle,
• a base-forming portion configured to form a base portion of the bottle, the base forming-portion having a lower segment which is globally semi-spherical,
• wherein the preform multilayered wall includes:
• an inner layer having an inner face intended to form the gaseous beverage side of the bottle,
• an outer layer having an outer face intended to form the outside of the bottle,
• a gas barrier layer sandwiched between the inner layer and the outer layer,
• the gas barrier layer extends along the entire preform multilayered wall except for a bottom ending portion which is free of barrier layer, this bottom ending portion free of barrier layer being a central part of the base-forming portion extending around the injecting point in a solid angle (α) comprised between 5° to 80°, the apex of this solid angle being the centre of the globally semi-spherical lower segment of the base-forming portion.