Patent GB-580941-A (GB)
Title: Artificial filaments of composite character and apparatus for producing them
IPC: D01D5/30
Filed: 1944-07-31
Abstract: Apparatus for making artificial filaments of composite character comprises a spinneret with a row of at least two orifices, partitions for dividing the space behind the spinneret face into at least three separate regions arranged side by side, one of these regions being disposed opposite the row of orifices and communicating with the two adjacent regions just behind the spinneret face along spaced planes in the vicinity of, but laterally offset on opposite sides from, the row of orifices, and conduits with separate channel systems associated with each of the separate regions for introducing filament-forming liquid of at least two different kinds, so that each of such liquids flows separately into alternate regions.  The arrangement of the partitions and orifices is such that two or more solutions are extruded through each orifice and the cross-section of the resulting composite filament comprises at least three distinct portions, adjacent portions being of different composition.  As shown in Figs. 1, 2 and 3, two different spinning solutions enter the nozzle through pipes 6, 7 and channels 8, 9, to compartments A, B. Parallel ribs 11 extend from plate 10 towards the back face of spinneret 2 without contacting it.  The spinneret has two rows of orifices 16 arranged in registry with alternate spaces between the ribs 11.  Thus, every other space between the ribs 11 faces a portion of the spinneret which is lacking in orifices while the intervening spaces are arranged in direct opposition to the orifices.  Passages 17 connect chamber B with the spaces between the ribs which face blank portions of the spinneret, and passages 18 connect chamber A with the spaces facing the orifices of the spinneret.  The cross-section of the filaments is governed by the natures of the different spinning solutions and by the relative rates of supply. Solutions containing the same filament-forming substance, but differing in the kind of solvent or the concentration, degree of polymerization, degradation, or degree of ripeness, or content of pigments or other additions, may be used. By using two spinning materials which shrink to a different extent during precipitation, drying, or after-treatment, there may be obtained strongly crimped threads.  Two solutions containing different cellulose esters, two albuminous substances, or a cellulose ester and a cellulose ether, may be used.  The spinning materials may belong to <PICT:0580941/IV/1> <PICT:0580941/IV/2> <PICT:0580941/IV/3> <PICT:0580941/IV/4> <PICT:0580941/IV/5> quite different classes of substances, e.g. cellulose and an albuminous substance, a cellulose ester or ether and an artificial resin or synthetic rubber.  The filaments may be formed by dry, wet, or melt-spinning processes. Nozzles with concentric rings of extrusion orifices may be used.  As shown in Figs. 4 and 7, a spinneret plate 2 with two concentric rings of orifices is used. Two different spinning solutions are supplied to compartments A and B and from there to alternate spaces between the concentric partitions 25 in the distributer member 24.  Passages 32 connect the spaces in front of and at the back of plate 22. Partitions 21 divide the space immediately at the back of the spinneret face into concentric annular spaces C1 to C4 and a central space C.  The spinning solutions immediately behind the spinneret face are thus arranged as concentric strata.  In an example, two viscose spinning solutions are prepared.  One is made from wood pulp and is aged to a salt point of 1.9; the other is made from cotton pulp and is aged to a salt point of 5.5.  The second solution contains an addition of titanium dioxide.  The clear and more aged viscose is caused to enter the space at the back of the spinneret face so as to be in a direct line with the orifices, while the pigmented viscose is caused to enter the spaces where there are no orifices.  The cross-section of the extruded filaments has a clear inner area almost surrounded by areas pigmented with titanium dioxide.  The filaments have a dull delustred appearance.  In another example, the titanium dioxide is added to the more aged viscose, the other viscose being clear. The filaments obtained have a glossy though delustred appearance owing to the presence of the delustrant in the core.