Spin pack and method for producing conjugate fibers
AssigneeHills Research & Development, Inc.
InventorWilliam H. Hills
Life of this patent
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Abstract
Sheath-core bi-component fibers are formed by an improvement of the method and apparatus described in U.S. Pat. No. 2,936,482 whereby molten sheath polymer is issued in ribbons into a recessed portion of the top surface of the spinneret from locations between rows of raised spinneret channel inlets. Ribbon flow of the sheath polymer is achieved in slot-like channels which are inter-leaved with rows of core polymer flow passages to optimize space utilization and spinneret channel density. Filtering of the core and sheath polymer is achieved in separate manifolds leading to the core flow passages and sheath slot-like flow channels which are kept to minimal length to minimize polymer residence time downstream of the filters.
Claims21
A fiber extrusion spin-pack for the production of sheath-core bi-component fibers by melt spinning, said spin-pack comprising:
- a spinneret having first and second opposite surfaces and a plurality of spaced polymer flow channels defined therethrough between said first and second surfaces, each flow channel having an inlet orifice defined within said first surface, said inlet orifices being arranged in a pattern of rows and columns along said first surface;
- plural core polymer flow passages having respective ingress openings, each core polymer flow passage arranged in spaced axial alignment with a respective flow channel inlet orifice, said core polymer passages and inlet openings being arrayed in a pattern of columns and rows corresponding to the pattern of inlet orifices in said spinneret;
- core polymer supply means for delivering pressurized molten core polymer to said plural core polymer flow passages;
- core polymer filtering means disposed flush against said ingress openings between said core polymer supply means and said core polymer flow passages for filtering and shearing core polymer delivered to said core polymer flow passages;
- wherein said core polymer flow passages define flow paths, from said filter means to respective spinneret inlet orifices, which are substantially equal in length and cross-sectional area to provide substantially equal core polymer pressure drops through said paths;
- plural sheath polymer flow passages, each disposed substantially midway between respective rows of said core polymer flow passages, said sheath polymer flow passages each terminating in respective outlet openings aligned with respective spaces between rows of said spinneret inlet orifices and which are at least co-extensive with adjacent rows of spinneret inlet orifices;
- sheath polymer supply means for delivery of pressurized molten sheath polymer of said sheath polymer flow passages;
- and
- sheath polymer filter means disposed between said sheath polymer supply means and said sheath polymer flow passages for filtering and shearing sheath polymer delivered to said sheath polymer flow passages.
The method of melt spinning sheath-core bi-component fibers of polymer material comprising the steps of:
- filtering and shearing a flow of pressurized molten core polymer at the entrances to multiple flow channels of substantially equal length and cross-section;
- directing multiple parallel streams of pressurized molten core polymer into respective spinneret flow channels from said multiple respective parallel flow passages positioned above and in axial alignment with the flow channels, said flow passages and flow channels each being arranged in a pattern of columns and rows;
- flowing plural ribbons of pressurized molten sheath polymer from slots located substantially midway between respective rows of flow passages into a portion of the spinneret surrounding inlets to the spinneret flow channels;
- and
- directing the sheath polymer from said portion of the spinneret to flow into said flow channels about said core polymer streams.
A fiber extrusion spin pack for the production of sheath-core bi-component fibers comprising:
- core polymer supply means for delivering molten core polymer under pressure;
- sheath polymer supply means for delivering molten sheath polymer under pressure;
- filter means for filtering and shearing the delivered molten sheath and core polymer, said filter means being capable of withstanding a molten polymer pressure P of at least 1000 psi;
- a spinneret having a plurality of orifices for delivering said fibers, the density D of said orifices being at least two orifices per square centimeter;
- a plurality of core polymer flow channels extending from said filter means for issuing molten core polymer streams into respective spinneret orifices, each core polymer flow channel having a volume Vc of less than 0.2 cubic centimeters;
- and
- a plurality of sheath polymer flow channels extending from said filter means for delivering molten sheath polymer to said spinneret orifices, each sheath flow channel having a volume Vs of less than 0.5 cubic centimeters per spinneret orifice served.
Dependencies are inferred from the claim text.