Method for forming multiaxially oriented containers

Claim 1

A method of forming a biaxially oriented container having a controlled distribution of wall thickness therein, said method comprising the steps of: a. continuously extruding an elongted, unconfined, hallow, thermoplastic parison at a temperature in excess of that at which substantial molecular orientation of the thermoplastic occurs; b. varying the thickness of the wall of the parison during extrusion in accordance with a predetermined program; c. closing separated sections of a conditioning mold on a portion of said variable wall thickness parison while pinching its end shut in the joint between said sections; d. introducing pressurized fluid into the conditioning mold-enclosed parison portion to expand it outwardly into contact with cooled surfaces of a cavity in the conditioning mold to form a self-supporting preform of varying wall thickness having an outer skin at reduced temperature; e. transferring said self-supporting preform from the conditioning mold to a temperature conditioning zone; f. reducing the temperature of inner wall sections of the variable wall thickness preform in said conditioning zone such that the entire wall thickness of such sections is within a temperature range at which substantial molecular orientation can occur, the thinner portions of such sections of said wall being at a lower temperature than the thicker portions; g. longitudinally stretching the temperature-conditioned preform to impart axial orientation thereto; and h. expanding the longitudinally stretched, variable wall thickness, temperature-conditioned preform radially outwardly against cooled surfaces of a cavity of a finishing mold to form the biaxially oriented container and reduce the temperature of the thermoplastic sufficiently to lock in the orientation stresses produced during the longitudinal and radial stretching, the thin, cooler portion of such sections of said preform stretching less than the thicker hotter portions thereof during said expansion, thereby producing said wall thickness distribution in said container.

Claim 2

A method of forming a biaxially oriented container having a controlled distribution of wall thickness therein, said method comprising the steps of: a. continuously extruding an elongted, unconfined, hallow, thermoplastic parison at a temperature in excess of that at which substantial molecular orientation of the thermoplastic occurs; b. varying the thickness of the wall of the parison during extrusion in accordance with a predetermined program; c. closing separated sections of a conditioning mold on a portion of said variable wall thickness parison while pinching its end shut in the joint between said sections; d. introducing pressurized fluid into the conditioning mold-enclosed parison portion to expand it outwardly into contact with cooled surfaces of a cavity in the conditioning mold to form a self-supporting preform of varying wall thickness having an outer skin at reduced temperature; e. transferring said self-supporting preform from the conditioning mold to a temperature conditioning zone; f. reducing the temperature of inner wall sections of the variable wall thickness preform in said conditioning zone such that the entire wall thickness of such sections is within a temperature range at which substantial molecular orientation can occur, the thinner portions of such sections of said wall being at a lower temperature than the thicker portions; g. longitudinally stretching the temperature-conditioned preform to impart axial orientation thereto; and h. expanding the longitudinally stretched, variable wall thickness, temperature-conditioned preform radially outwardly against cooled surfaces of a cavity of a finishing mold to form the biaxially oriented container and reduce the temperature of the thermoplastic sufficiently to lock in the orientation stresses produced during the longitudinal and radial stretching, the thin, cooler portion of such sections of said preform stretching less than the thicker hotter portions thereof during said expansion, thereby producing said wall thickness distribution in said container.

Claim 11

A method of making a biaxially oriented, narrow necked container having controlled wall thickness distribution from a high nitrile polymer, said method comprising: a. extruding a thermoplastic parison of said high nitrile polymer at a temperature within the range of between 400* to 500*F.; b. increasing the thickness of one portion of said parison with respect to another portion during said extrusion; c. enclosing said variable wall thickness parison in a conditioning mold; d. expanding said variable wall thickness parison incrementally outwardly against cooled walls of a cavity in said conditioning mold to form a preform having a molded neck finish and an elongated body containing said variable thickness portions; e. reducing the temperature of the body of said preform such that it is within the range of between 250* to 325* F., the average temperature of the wall of the thickened portion corresponding to the thickened portion of the parison being within said temperature range but incrementally greater than the average wall temperature of said another portion of said body; f. increasing the length of said temperature-conditioned preform such that the thickened portion at said incrementally greater average wall temperature stretches more than said another portion and is consequently reduced in thickness, said length increase creating uniaxial molecular orientation in the preform; and g. expanding the thus increased-length preform radially outwardly against the wall of a cavity corresponding to the configuration of the container to create radial orientation in the thermoplastic and form said biaxially oriented container.

Claim 12

A method of making a biaxially oriented, narrow necked container having controlled wall thickness distribution from a high nitrile polymer, said method comprising: a. extruding a thermoplastic parison of said high nitrile polymer at a temperature within the range of between 400* to 500*F.; b. increasing the thickness of one portion of said parison with respect to another portion during said extrusion; c. enclosing said variable wall thickness parison in a conditioning mold; d. expanding said variable wall thickness parison incrementally outwardly against cooled walls of a cavity in said conditioning mold to form a preform having a molded neck finish and an elongated body containing said variable thickness portions; e. reducing the temperature of the body of said preform such that it is within the range of between 250* to 325* F., the average temperature of the wall of the thickened portion corresponding to the thickened portion of the parison being within said temperature range but incrementally greater than the average wall temperature of said another portion of said body; f. increasing the length of said temperature-conditioned preform such that the thickened portion at said incrementally greater average wall temperature stretches more than said another portion and is consequently reduced in thickness, said length increase creating uniaxial molecular orientation in the preform; and g. expanding the thus increased-length preform radially outwardly against the wall of a cavity corresponding to the configuration of the container to create radial orientation in the thermoplastic and form said biaxially oriented container.

Claim 13

A METHOD OF FORMING A MOLECULARLY ORIENTED CONTAINER WHICH COMPRISES: A. EXTRUDING AN UNCONFINED, HOLLOW THERMOPLASTIC PARISON AT A TEMPERATURE IN EXCESS OF THAT AT WHICH SUBSTANTIAL MOLECULAR ORIENTATION OF THE THERMOPLASTIC OCCURS ON STRETCHING; B. CLOSING SECTIONS OF A PARISON CONDITIONING AND SHAPING MOLD ON SAID PARISON TO ENCLOSE SAID PARISON THEREIN WHILE PINCHING ITS END SHUT BETWEEN THE SECTIONS; C. SUBJECTING THE ENCLOSED PARISON TO A DEFORMING PRESSURE WHILE AT SAID TEMPERATURE TO EXPAND IT OUTWARDLY AGAINST COOLED MOLDING SURFACES OF SAID CONDITIONING AND SHAPING MOLD TO FORM A PREFORM HAVING A BODY PORTION AND A MOLDED FINISH; D. TRANSFERRING SAID PREFORM WHILE STILL IN A PRESSURE SENSITIVE BUT DIMENSIONALLY STABLE STATE FROM THE CONDITIONING AND SHAPING MOLD TO A TEMPERATURE CONDITIONING ZONE; E. BRINGING THE TEMPERATURE OF THE THERMOPLASTIC OF AT LEAST THE BODY PORTION OF THE PREFORM IN THE CONDITIONING ZONE TO WITHIN THE RANGE AT WHICH SUBSTANTIAL MOLECULAR ORIENTATION OF THE THERMOPLASTIC OCCURS ON STRETCHING; F. TRANSFERRING THE PREFORM FROM THE CONDITIONING ZONE TO A FINISHING MOLD AFTER THE TEMPERATURE OF THE BODY PORTION THEREOF HAS REACHED SUCH RANGE; AND G. LONGITUDINALLY STRETCHING AND RADIALLY EXPANDING THE BODY PORTION ONLY OF SAID PREFORM WHILE WITHIN SAID TEMPERATURE RANGE AGAINST MOLDING SURFACES OF THE FINISHING MOLD TO FORM SAID MOLECULARLY ORIENTED CONTAINER.

Claim 14

A METHOD OF FORMING A MOLECULARLY ORIENTED CONTAINER WHICH COMPRISES: A. EXTRUDING AN UNCONFINED, HOLLOW THERMOPLASTIC PARISON AT A TEMPERATURE IN EXCESS OF THAT AT WHICH SUBSTANTIAL MOLECULAR ORIENTATION OF THE THERMOPLASTIC OCCURS ON STRETCHING; B. CLOSING SECTIONS OF A PARISON CONDITIONING AND SHAPING MOLD ON SAID PARISON TO ENCLOSE SAID PARISON THEREIN WHILE PINCHING ITS END SHUT BETWEEN THE SECTIONS; C. SUBJECTING THE ENCLOSED PARISON TO A DEFORMING PRESSURE WHILE AT SAID TEMPERATURE TO EXPAND IT OUTWARDLY AGAINST COOLED MOLDING SURFACES OF SAID CONDITIONING AND SHAPING MOLD TO FORM A PREFORM HAVING A BODY PORTION AND A MOLDED FINISH; D. TRANSFERRING SAID PREFORM WHILE STILL IN A PRESSURE SENSITIVE BUT DIMENSIONALLY STABLE STATE FROM THE CONDITIONING AND SHAPING MOLD TO A TEMPERATURE CONDITIONING ZONE; E. BRINGING THE TEMPERATURE OF THE THERMOPLASTIC OF AT LEAST THE BODY PORTION OF THE PREFORM IN THE CONDITIONING ZONE TO WITHIN THE RANGE AT WHICH SUBSTANTIAL MOLECULAR ORIENTATION OF THE THERMOPLASTIC OCCURS ON STRETCHING; F. TRANSFERRING THE PREFORM FROM THE CONDITIONING ZONE TO A FINISHING MOLD AFTER THE TEMPERATURE OF THE BODY PORTION THEREOF HAS REACHED SUCH RANGE; AND G. LONGITUDINALLY STRETCHING AND RADIALLY EXPANDING THE BODY PORTION ONLY OF SAID PREFORM WHILE WITHIN SAID TEMPERATURE RANGE AGAINST MOLDING SURFACES OF THE FINISHING MOLD TO FORM SAID MOLECULARLY ORIENTED CONTAINER.