Continuous extrusion-compression molding process for making optical articles

A method of forming an optical article comprising:

• supplying a conveyor having a plurality of spaced die supports for a lower die and an upper die forming an optical article forming die set;
• moving the conveyor;
• forming a melt of an optical polymeric material in a melting apparatus and feeding the melt from the apparatus in the form of an unpressurized melt strand;
• supplying a lower die from a lower die supply device onto one of the die supports;
• forming and adding a predetermined melt shot portion of the unpressurized melt strand to the upper surface of the lower die;
• supplying an upper die from an upper die supply device and positioning the upper die on top of the unpressurized melt forming a melt containing die set comprising, in sequence, a lower die, polymeric material and an upper die;
• compressing the melt containing die set using a press associated with the die support forming an optical article;
• releasing the press when the optical article is formed;
• removing the die set from the conveyor;
• removing the optical article from the die set;
• recycling the lower die and upper die of the die set to their respective supply devices;
• and
• repeating the above steps until the desired number of optical articles are made.

An apparatus for making optical articles comprising:

• a rotatable turntable for supporting a plurality of lower dies and upper dies, the lower and upper dies forming a die set;
• heating means for heating the dies and/or the turntable;
• a plurality of support means associated with the turntable to support each of the die sets;
• a plurality of compression means associated with each of the support means of the turntable for compressing a melt containing die set to form an optical article;
• ejection means for removing the optical article containing die set from the rotating turntable;
• melting means for forming a melt of an optical polymeric material and feeding the melt from the melting means in the form of an unpressurized melt strand;
• lower die supply means for supplying a lower die to a support means to receive a portion of the melt strand;
• melt supply means for feeding the unpressurized melt strand to the upper surface of the lower die and forming the unpressurized melt strand into a predetermined unpressurized melt shot portion;
• and
• upper die supply means for supplying an upper die to the top of the unpressurized melt shot containing lower die forming a melt containing die set comprising, in sequence, a lower die, polymer melt and upper die;
• wherein the melt containing die set is compressed using the compression means to form the optical article, the die set is rotated on the turntable for a desired time and the compression means deactivated and the die set is then ejected from the turntable using the ejection means, the formed optical article is separated from the upper die and lower die and the lower die and upper die recycled to their respective supply means.

An apparatus for making optical articles comprising:

• a conveyor for supporting a plurality of lower dies and upper dies, the lower and upper dies forming a die set;
• heating means for heating the dies and/or the conveyor;
• a plurality of support means associated with the conveyor to support each of the die sets;
• a plurality of compression means associated with each of the support means of the conveyor for compressing a melt containing die set to form an optical article;
• ejection means for removing the optical article containing die set from the conveyor;
• melting means for forming a melt of an optical polymeric material and feeding the melt from the melting means in the form of an unpressurized melt strand;
• lower die supply means for supplying a lower die to a support means to receive a portion of the melt strand;
• melt supply means for feeding the unpressurized melt strand to the upper surface of the lower die and forming the unpressurized melt strand into a predetermined unpressurized melt shot portion;
• and
• upper die supply means for supplying an upper die to the top of the unpressurized melt shot containing lower die forming a melt containing die set comprising, in sequence, a lower die, polymer melt and upper die;
• wherein the melt containing die set is compressed using the compression means to form the optical article, the die set is moved on the conveyor for a desired time and the compression means deactivated and the die set is then ejected from the conveyor using the ejection means, the formed optical article is separated from the upper die and lower die and the lower die and upper die recycled to their respective supply means.