Method and apparatus for producing sealed and filled containers
First Claim
1. A method of producing a sealed and filled container comprising providing a preform of crystallizable plastic material having a body, a closed bottom portion and an open mouth portion, filling the preform with goods to be sealed therein, applying a mechanical forming and thermocrystallizing tool against the closed bottom portion of the preform, with pressure, to reshape the bottom portion of the preform by displacing at least a part of the bottom portion of the preform inwardly of the body towards the open mouth of the preform, heating the tool at the surface thereof applied against the bottom portion of the preform to raise the temperture of said bottom portion to a value greater than the glass transition temperature (Tg) of the plastic material, maintaining contact of the heated tool with the bottom portion during its reshaping for a length of time sufficient for the plastic material to obtain thermocrystallization of at least 15% at least at the surface in contact with said tool, the thermocrystallization of the bottom portion causing strengthening of said bottom portion and mechanical stability in its reshaped state to resist deformation and relatively high tempertures, and sealing said open mouth portion to produce a sealed and filled container.
1 Assignment
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Accused Products
Abstract
A method and apparatus for producing a sealed and filled container in which a preform of crystallizable plastic material having a body, a closed bottom portion and an open mouth portion is filled with the goods to be sealed therein whereafter a mechanical forming and thermocrystallizing tool is applied against the closed bottom of the preform, with pressure, to reshape the bottom of the preform by displacing at least a portion of the bottom of the preform inwardly of the body towards the open mouth of the preform. The tool is heated so that the temperature of the bottom portion is greater than the glass transition temperature (Tg) of the plastic material and the tool is maintained in contact with the bottom portion during its reshaping for a length of time sufficient for the plastic material to obtain a total crystallization of at least 15%. The open mouth portion is sealed to produce a sealed and filled container.
164 Citations
20 Claims
- 1. A method of producing a sealed and filled container comprising providing a preform of crystallizable plastic material having a body, a closed bottom portion and an open mouth portion, filling the preform with goods to be sealed therein, applying a mechanical forming and thermocrystallizing tool against the closed bottom portion of the preform, with pressure, to reshape the bottom portion of the preform by displacing at least a part of the bottom portion of the preform inwardly of the body towards the open mouth of the preform, heating the tool at the surface thereof applied against the bottom portion of the preform to raise the temperture of said bottom portion to a value greater than the glass transition temperature (Tg) of the plastic material, maintaining contact of the heated tool with the bottom portion during its reshaping for a length of time sufficient for the plastic material to obtain thermocrystallization of at least 15% at least at the surface in contact with said tool, the thermocrystallization of the bottom portion causing strengthening of said bottom portion and mechanical stability in its reshaped state to resist deformation and relatively high tempertures, and sealing said open mouth portion to produce a sealed and filled container.
- 15. Apparatus for producing a sealed and filled container from a preform of crystallizable plastic material having a body, a closed bottom portion and an open mouth portion, said apparatus comprising holder means for supporting a preform at the bottom portion thereof in a perimetral region while leaving the bottom portion exposed at an opening in said holder means within said perimetral region, means for filling the preform with goods to be sealed therein, a mechanical forming and thermocrystallizing tool supported for displacement adjacent to said holder means to traverse said opening and bear against the closed bottom portion of the preform, with pressure, to reshape the bottom portion of the preform by displacing at least a portion of the bottom portion of the preform inwardly of the body towards the open mouth of the preform, means for heating the tool at the surface thereof applied against the bottom portion of the preform so that the temperature of said bottom portion is greater than the glass transition temperature (Tg) of the plastic material, stop means between the holder means and said tool for limiting the passage of the tool through said opening and for maintaining contact of the heated tool with the bottom portion during reshaping of the latter for a length of time sufficient for the plastic material to obtain a total thermocrystallization of at least 15% at least at the surface in contact with said tool, and means for sealing said open mouth portion to produce a sealed and filled container.
Specification