Process for preparing partially dissolvable and splittable conjugated microfiber

  • US 5,047,189 A
  • Filed: 03/29/1990
  • Issued: 09/10/1991
  • Est. Priority Date: 05/11/1990
  • Status: Expired due to Term
First Claim
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1. A process for preparing a conjugated polymer microfilament comprising a polyamide central portion surrounded by a polyester portion, where in a cross-section of the conjugated microfilament the polyamide forms a matrix comprising a plurality of orange-wedge shaped islands all slightly connected at a common center and separated and surrounded by the polyester, the number of polyamide orange-wedge shaped islands being in the range 3 to 12 so that upon an outermost surrounding portion of said polyester being dissolved the remaining polyester and polyamide can be split into 3 to 12 sections of polyester and 3 to 12 sections of polyamide for a corresponding total of 6 to 24 split conjugated filaments of polyester and polyamide, the process comprising the steps of:

  • separately melting and metering respective flows of said polyester and said polyamide;

    extruding said metered flows of melted polyester and polyamide through a conjugated spinneret with the polyester separating the orange-wedge shaped polyamide islands all slighty connected to a common center and separating said islands and surrounding the polyamide, the conjugated fiber being extruded at a temperature at the range 270°

    to 300°

    C., a dynamic viscosity during said extrusion being in the range 2000 to 3500 poises for said polyester and in the range 800 to 2500 poises for the polyamide, a take-up speed for the conjugated extruded fiber being in the range 500 to 4000 m/min, andpassing the undrawn conjugated yarn obtained from the conjugated spinneret through a belt-nip twister with a draw ratio in the range 1.5 to 4.5, at a speed in the range 300 to 600 m/min, at a drawing temperature in the range 100°

    to 180°

    C.,said nip twister having a twist level in the range 3000 to 4000 T/M, a belt cross angle in the range 110°

    to 130°

    , a ratio of belt speed/yarn speed between 1.62 and 2.2, a second feed roller of said nip twister having an overfeed in the range 1.5 to 2.5%, and a third feed roller of said nip twister having an overfeed in the range 2.0 to 3.5%,the conjugated textured yarn thus obtained having a titer in the range 300 to 450 d and a filament count in the range 12 to 128, with the titer per filament in the range 0.01 to 0.5 d and a sub-resolving ratio=(weight of unsplit yarn-weight of split yarn upon dissolving of an outermost portion of polyester)/(weight of unsplit yarn) being in the range 0.1 to 0.4.

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