Process of making polymeric fibers

Details Process of making polymeric fibers Process of making polymeric fibers

1999-07-19

2001-04-03

Tentoni, Leo B. (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

Direct application of electrical or wave energy to work

Reshaping, drawing or stretching

C264S168000, C264S235600, C264S290500, C264S481000

Reexamination Certificate

active

06210622

ABSTRACT:

BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to the production of synthetic polymeric material in filament form for use in fiber manufacture and, more particularly, to apparatus and method for drawing, heat setting, and crimping such filamentary material, particularly polyethylene terephthalate (PET) commonly referred to as polyester. In particular, the present invention relates to a new draw line for tow having an undrawn denier of about 3 million or greater and a drawn tow having a denier of 1.0 million denier or greater. More specifically, the present invention relates to drawing, heat setting and crimping of a polymeric tow, whereby the tow has a constant denier per inch of width after drawing.
2) Prior Art
In the conventional manufacture of synthetic yarns, a molten polymeric material is extruded in the form of multiple continuous filaments which, after quenching to cool the filaments, are gathered and transported longitudinally in a lengthwise co-extensive bundle commonly referred to as a tow. Particularly with polymeric materials such as PET, the tows are subjected to a subsequent drawing and heating operation to orient and heat set the molecular structure of each constituent filament in each tow.
A typical drawing and heat setting operation involves transporting multiple tows in side-by-side relation sequentially through two or more drawstands operating at progressively greater driven speeds to exert a lengthwise stretching force on the tows and their individual filaments while traveling between the drawstands thereby performing a drawing to molecularly orient the individual filaments, followed by a calender structure about which the tow travels peripherally in a sinuous path to be sufficiently heated to set the molecular orientation of the filaments. Normally, the tow is transported through a quench stand to be cooled immediately following the calender structure and finally a number of tows are combined together in a stacker and transported to a crimper, such as a so called stuffer box, to impart texture and bulk to the filaments.
Conventional draw-line-stands spread out the tow in a ribbon-like shape before drawing the filaments of the tow and the flattened tow is not recombined until after quenching and before the crimper. Conventional draw-line-stands employ cantilevered rolls for the drawing operation of the ribbon-like tow, which requires the supporting walls to be very large, and the mechanical bearing structures of the cantilevered rolls to be sufficiently massive to support the rolls and resist the bending moments and deflective forces imposed by tows of the size and denier conventionally being processed.
U.S. Pat. No. 2,918,346 to Paulsen discloses a process for orienting a dense tow of polyester filaments. Paulsen discloses heating the tow band in a heated bath and drawing the tow 2.3 to 5.8 times its original length. In Example 3, Paulsen discloses an undrawn tow having a density of 142,000 denier per inch, corresponding to a drawn density between about 24,000 and 62,000 denier per inch.
U.S. Pat. No. 3,259,681 to Bull et al. schematically illustrates a process for making polyester tow starting from the spinnerette and continuing, through the drawing stages, heat setting, and lastly crimping of the tow. In Example 4 of this patent an undrawn tow of 130,000 denier per inch is disclosed.
U.S. Pat. No. 3,567,817 to Spiller discloses a process for drawing a tow by means of a series of rolls, including hot liquid to heat the tow between draws. In Example 4 of this patent,an undrawn polyester tow of approximately 267,000 denier per inch is disclosed.
While the patents to Paulsen, Bull et al. and Spiller disclose large denier tows, these are undrawn. The present invention produces drawn tows of 150,000 denier/inch or greater.
Tow drawing and heat setting lines of the type described above have proven to be reasonably effective and reliable for the intended purpose. However, as the fiber industry continually strives to improve efficiency and reduce manufacturing costs, much effort has been devoted to attempts to increase the number of filaments in each tow and to increase the lineal speed at which the filaments are processed through the drawing and heat setting line, which presents particular difficulties and problems in construction of the apparatus within the line and in effectively accomplishing heat setting of all of the constituent filaments in a tow.
SUMMARY OF THE INVENTION
The present invention seeks to overcome the massive construction of the conventional draw-line-stand by employing massive undrawn tows of 3 million denier or larger. Unlike conventional draw-lines which use a stacker after quenching to combine several tows, the present invention stacks or combines several tows before the drawing stage such that the massive tow travels through the entire draw-line to the crimper. By avoiding a conventional draw-line, which spreads a tow into a ribbon like shape, the massive tow is formed into a flattened shape, but it is not ribbon-thin. Instead it is thick like a very thick belt and has 150,000 denier/inch or greater as it traverses the drawstand, heat setting apparatus, and the crimper. The construction of the cantilevered rolls of the present invention are significantly shorter than conventional rolls . Accordingly the construction of the cantilevered rolls of the present invention do not require massive structural support and massive load bearing characteristics. Therefore, the apparatus of the present invention is significantly cheaper in capital costs.
The present invention comprises an apparatus and method for drawing, heat setting, quenching and crimping a massive tow.
In the broadest sense, the present invention comprises a process for the production of tow fibers composed of the steps of drawing, heat setting, and crimping at a nominal constant drawn denier per inch of the width of the tow.
In the broadest sense, the present invention comprises a process for drawing and heat setting a fiber bundle having a drawn density of greater than 150,000 denier per inch of width.
In the broadest sense, the present invention comprises stacker apparatus, drawing apparatus, and heat setting apparatus, each arranged such that a tow fiber bundle travels in succession from the stacker apparatus through the heat setting apparatus in a compacted form.


REFERENCES:
patent: 2918346 (1959-12-01), Paulsen
patent: 3259681 (1966-07-01), Bull et al.
patent: 3364294 (1968-01-01), Garibian et al.
patent: 3567817 (1971-03-01), Spiller
patent: 3816486 (1974-06-01), Vail
patent: 3894135 (1975-07-01), Riggert et al.
patent: 3972127 (1976-08-01), Hoshi et al.
patent: 4105740 (1978-08-01), Yasuda et al.
patent: 4112668 (1978-09-01), Spiller
patent: 4704329 (1987-11-01), Hancock et al.
patent: 5073322 (1991-12-01), Hansen
patent: 5175239 (1992-12-01), Gauntt et al.
patent: 5375310 (1994-12-01), Greifeneder et al.
patent: 5679300 (1997-10-01), Lorenz et al.
patent: 423 807 A1 (1991-04-01), None
patent: 493050 (1992-07-01), None
patent: 540062 (1993-05-01), None
patent: 1219154 (1971-01-01), None
patent: 51-32816 (1976-03-01), None
patent: 53-45417 (1978-04-01), None
patent: 63-135516 (1988-06-01), None
patent: 594220 (1978-02-01), None
patent: 958529 (1982-09-01), None
patent: 1700116 A1 (1991-12-01), None
K.R. Riggert, “The Drawing of Polyester Tow” Chemiefasern/ Textilindstrie, pp. 638-648, —(Sep. 1981).
Fiber Producer, Dec. 1976.

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