Partial crystallization method of amorphous plastic articles

The process which comprises:

• forming a plastic article by injecting molten plastic into an injection mold at an elevated temperature;
• cooling the plastic from the molten condition to a solid condition;
• wherein a first portion of the molten plastic is rapidly cooled from the molten condition to the solid condition by a first means adjacent said first portion to form an amorphous first portion, and a second portion of the plastic is slowly cooled from the molten condition to the solid condition by a second means adjacent said second portion to form a crystallized second portion;
• wherein said article has a closed bottom, a sidewall portion extending from the closed bottom, and a neck region extending from the sidewall, wherein said second portion includes said neck region, including the step of crystallizing at least a portion of the neck region to form a neck region where the crystallized portion thereof has a higher strength than the body region;
• and
• including providing a mold core of said injection mold, forming a cooling channel inside said mold core with coolant flow therein operative to cool said first and second portions, and forming a cooling restriction in said cooling channel adjacent said neck region for slowly cooling said plastic adjacent at least a portion of the neck region to form said crystallized second portion at said neck region, while rapidly cooling said closed bottom and sidewall to form said amorphous portion at said closed bottom and sidewall.