Plastic aerosol container and method of manufacture

A method of making a plastic aerosol container from a preform of crystallizable polymer, the preform comprising:

• an upper preform portion and a lower preform portion,
• the upper preform portion including a neck finish configured to receive an aerosol valve and closure assembly;
• the lower preform portion including a tapered shoulder configured to be expanded by blow molding to form an expanded biaxially strain oriented shoulder of an aerosol container body;
• the lower preform portion further including a sidewall configured to be expanded by blow molding to form an expanded biaxially strain oriented sidewall of the aerosol container body;
• the method comprising steps of:
• creating a pull point at which biaxial strain orientation begins below the neck finish of the preform by thermally crystallizing the preform neck finish while the lower preform portion including the tapered preform shoulder and sidewall remain thermally uncrystallized;
• blow molding the lower portion of the preform from the pull point to form an expanded biaxially strain oriented container shoulder, formed from the thermally uncrystallized tapered preform shoulder, and an expanded biaxially strain oriented container sidewall, formed from the thermally uncrystallized preform sidewall, wherein the Dull point is a line of demarcation between the thermally crystallized neck finish and the biaxially strain oriented shoulder of the container body;
• and
• wherein the thermally crystallized neck finish and the junction defining the pull point at which biaxial strain orientation began provide a structural integrity resisting deformation such that the plastic aerosol container, with an aerosol valve and closure assembly having a crimp or thread configured to seal the valve and closure assembly to the neck finish, can withstand a hot water bath test wherein the container is filled with 60% water and 40% nitrogen pressurized to 130 psig and submerged in a hot water bath of 153 deg. F. for 30 minutes and shows no leakage at the closure and no signs of distortion.

A preform for blow molding a plastic aerosol container comprising:

• an upper preform portion and a lower preform portion,
• the upper preform portion being thermally crystallized and including a thermally crystallized neck finish configured to receive an aerosol valve and closure assembly, the aerosol valve and closure assembly including a crimp or thread configured to seal the valve and closure assembly to the neck finish;
• the lower preform portion not being thermally crystallized and including a thermally uncrystallized tapered shoulder configured to be expanded by blow molding to form an expanded biaxially strain oriented shoulder of an aerosol container body;
• the lower preform portion further including a thermally uncrystallized sidewall configured to be expanded by blow molding to form an expanded biaxially strain oriented sidewall of the aerosol container body;
• a junction between the thermally crystallized upper preform portion and the shoulder of the lower preform portion defining a pull point at which the biaxial strain orientation begins, wherein the pull point is a line of demarcation between the thermally crystallized neck finish and the biaxially strain oriented shoulder of the container body;
• and
• wherein the thermally crystallized neck finish and the junction defining the pull point at which biaxial strain orientation began provide a structural integrity resisting deformation such that the plastic aerosol container and an aerosol valve and closure assembly sealed to the neck finish can withstand a hot water bath test wherein the plastic aerosol container is filled with 60% water and 40% nitrogen pressurized to 130 psig and submerged in a hot water bath of 153 deg. F. for 30 minutes and shows no leakage at the closure and no signs of distortion.