Container preform made of plastics material

A method for manufacturing a container by blow molding or stretch-blow molding, the method comprising at least the following steps:

• providing a preform;
• heating a body of the preform by exposure to monochromatic or quasi-monochromatic infrared radiation of a predetermined intensity to form a preheated preform;
• and
• forming the container by injecting a pressurized fluid into the preheated preform;
• wherein the preform comprises:
• the body, wherein the body is rotationally symmetrical about a vertical central axis, the body having an outer wall and an inner wall, wherein a radial distance between the outer wall and the inner wall defines a wall thickness;
• an open neck that extends as a continuation of the body from an upper end thereof, the neck being separated from the body by an annular collar;
• and
• a base that closes the body from a lower end thereof, the base being rotationally symmetrical about the central axis;
• wherein the body has a substantially frustoconical shape widening from the base to the neck and has a portion that is concave in axial section,
• wherein the wall thickness has a first thickness E2 beneath the collar at an under-neck reference height Hr,
• wherein towards the base, the wall thickness has a second thickness E over a cone height Hc and a third thickness E1 at the lower end of the body, and
• wherein the third thickness E1 is between 0.7 E and 1.2 E and the first thickness E2 is between 0.5 E and 1.0 E.

A mold for forming a preform, the mold comprising:

• a mold body having a lateral wall with an impression of an outer face of a body of the preform;
• a mold base having an impression of an outer face of a base of the preform;
• and
• a core having an impression of an inner face of the preform;
• wherein the preform comprises:
• the body, wherein the body is rotationally symmetrical about a vertical central axis, the body having an outer wall and an inner wall, wherein a radial distance between the outer wall and the inner wall defines a wall thickness;
• an open neck that extends as a continuation of the body from an upper end thereof, the neck being separated from the body by an annular collar;
• and
• the base that closes the body from a lower end thereof, the base being rotationally symmetrical about the central axis;
• wherein the body has a substantially frustoconical shape widening from the base to the neck and has a portion that is concave in axial section,
• wherein the wall thickness has a first thickness E2 beneath the collar at an under-neck reference height Hr,
• wherein towards the base, the wall thickness has a second thickness E over a cone height Hc and a third thickness E1 at the lower end of the body, and
• wherein the third thickness E1 is between 0.7 E and 1.2 E and the first thickness E2 is between 0.5 E and 1.0 E.