SEVEN HOLE SPINNERET

Abstract: Segmented spinning capillaries for post-coalescent spinning provide the capability to spin round cross-section filaments with round continuous voids along the length of the filaments by adding an inner arcuate slot (44) at the base of each spoke (43) of each slot segment (40).

Description: This invention relates to spinnerets and, more particularly, it relates to spinnerets for spinning substantially round filaments having a plurality of longitudinal voids along their lengths. EP-A-0317192 which represents a state of art under Article 54(3) EPC shows a spinneret orifice design in which six orifices are arranged in the surface of the spinneret so that polymer will be extruded through each orifice and then coalesce to form a round filament with seven equisized and equispaced voids. Summary of the Invention A spinneret for the production of the filaments described in EP-A-0317192 comprises a plate having upper and lower surfaces connected by a capillary. The capillary is formed of a plurality of segments. Each segment is comprised of an outer and an inner arcuate slot joined by a rectangularly shaped slot that places the arcuate slots in communication with each other. The segments are equally spaced a distance from the center of the capillary and are equally spaced angularly about the center of the capillary. The rectangular slot connecting the inner and outer arcuate slots has a width greater than that of the inner arcuate slot but less than that of the outer arcuate slot. In a preferred embodiment, the slot joining the inner and outer arcuate slots joins them at a central location. The spinneret is a one piece Spinneret which does location. not suffer the disadvantages of multi-part spinnerets which are adapted to form hollow fibers. Brief Description of the Drawings Figs. 1 and 2 are side elevation and lower surface views, respectively, of the spinneret of this invention. Fig. 3 is an enlarged view of a spinneret capillary viewed from the lower surface of the spinneret of Figs. 1 and 2. Detailed Description of the Preferred Embodiment Referring now to Figs. 1-3, spinneret 20 is adapted to be mounted in a filter pack (not shown) for supplying polymer to be spun into filaments. The spinneret 20 is formed from a plate 22 and is provided with a plurality of capillaries 24 connecting its upper and lower surfaces 26, 28, respectively. The capillary 24 is formed of six individual segments designated 40, 50, 60, 70, 80 and 90. Each segment is spaced an equal distance d from the center c of the capillary and also the segments are equispaced from each other angularly about the center c at an angle A . Each of the segments are the same dimensions and for purposes of description segment 40 will be described in detail. More particularly, segment 40 includes an outer arcuate slot 42 connected to an inner arcuate slot 44 by another slot 43. In the configuration of capillary 24 the width 48 of slot 43 is greater than the width 46 of inner arcuate slot 44 and the width 49 of the outer arcuate slot 42 is greater than the width 48 of arm 43. A typical capillary has an outside diameter D of 0.062" (0.16 cm) a length d of 0.012" (0.03 cm), and an angle A of about 60°. The relationship of the widths 46, 48 and 49 is as follows: width 48 is about 1.1 times width 46 and width 49 is about 1.2 times width 46.

Claims: A spinneret (20) for the production of filaments of essentially round cross-section with at least seven continuous voids along the filaments, one void being centrally located, said spinneret (20) comprising: a plate (22) having upper and lower surfaces (26, 28) connected by a capillary (24), said capillary (24) being defined at said lower surface (28) by a plurality of segments (40, 50, ..., 90) equispaced a distance (d) from and equispaced angularly about the center (c) of the capillary (24), each of said segments (40, 50, ..., 90) being defined by an inner arcuate slot (44), connected to an outer arcuate slot (42) by another slot (43), whereby said slot (43) connecting the inner and outer arcuate slots (44, 42) is rectangular in shape and has a width (48) that is greater than the width (46) of the inner arcuate slot (44) and said outer arcuate slot (42) has a width (49) greater than the width (48) of the slot (43) connecting the inner and outer arcuate slots (44, 42).

Inventors: BROADDUS, CLARKE RUST
Applicants: E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1988
Main classification: D01D5
IPC codes: D01F6, D01D5