Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1997-06-12
1999-07-20
Edwards, Newton
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
428395, D02G 300
Patent
active
059254602
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention pertains to a process for manufacturing polyester filament yarn for technical applications by spinning a polymer over 90% of the chains of which are composed of ethylene terephthalate units, with the spinning process having the following elements:
extruding the polymer in the molten state through a spinneret plate,
passing the thus formed filaments through a heated zone and a cooling zone in that order,
fixing the filament speed,
drawing the filaments to a length of 1.5 to 3.5 times their original length, and
winding the resulting filament yarn, with all elements being covered in a single process pass.
Such a process is well-known. For instance, European patent application EP 80 906 describes a process for the production of polyester filament yarn for technical applications by melt-spinning a polyester-containing polymer in which all process elements are covered in a single process pass. Such a process is also known as a one-step process. It is indicated in this publication that in such a process it is preferred to select a winding speed of less than 5500 m/min, since higher winding speeds will give rise to filamentation and difficulty in operation.
However, an increase in the winding speed is desired. When manufacturing polyester filament yarn for technical applications on an industrial scale, it is advantageous to produce the largest possible quantity of yarn per unit of time on an appropriate apparatus. One of the ways of increasing the quantity of yarn produced per unit of time lies in a higher winding speed.
U.S. patent specification No. 4,491,657 also discloses the process mentioned in the opening paragraph. This patent specification states that the winding speed of the yarn in such a one-step process is not less than 6.5 km/min. However, there are no examples in this patent specification of polyester filament yarns for technical applications made by such a one-step process at such a winding speed, nor is there any teaching on how to solve the problems which were found to occur when making polyester filament yarns for technical applications at such winding speeds.
Patent application WO 90/00638 indicates that in a one-step spinning process an increase in the spinning speed goes hand in hand with increased crystallinity of the as yet undrawn filaments. Yarn wound at a speed of about 4800 m/min can be obtained from undrawn filaments having a crystallinity in the range of 13 to 18%.
SUMMARY OF THE INVENTION
The invention pertains to a process which makes it possible to manufacture polyester filament yarn for technical applications at high winding speeds without the aforementioned problems occurring. The term winding speed in this context is defined as the peripheral velocity of the package being wound.
DETAILED DESCRIPTION OF THE INVENTION
The invention consists in that when manufacturing polyester filament yarn for technical applications in the manner described in the above paragraph,
the filaments prior to being drawn have a crystallinity smaller than 16% and
the winding speed of the yarn is larger than 6000 m/min.
Surprisingly, it has proved possible to make polyester yarn for technical applications using a higher winding speed than the one commonly used so far when manufacturing such a yarn. The process conditions selected should be such that at a yarn winding speed above 6000 m/min, the crystallinity of the undrawn filaments is smaller than 16%.
It was found that if at such winding speeds the undrawn filaments have a crystallinity in excess of 16%, the result will be an unstable spinning process with a great deal of filamentation in the drawn yarn or a process which does not result in a yarn with advantageous use properties.
The crystallinity of the undrawn filaments can, e.g., be affected by: the polymer viscosity, the spinning temperature, the length of the heated zone, the temperature in the heated zone, the degree of cooling in the cooling zone, and the mass per unit length (linear density) of the filaments.
It is preferred, when making polyester
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patent: 4973657 (1990-11-01), Thaler
patent: 5009829 (1991-04-01), Roos
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ASTM D 2256 95a Standard Test Method for Tensile Properties of Yarns by the Single-Strand Method.sup.1, Annual Book of ASTM Standards, vol. 14.02 (pp. 564-572). Date Sep. 1995.
BISFA--"Internationally agreed methods for testing polyester filament yarns", The International Bureau for the Standarisation of Man-Made Fibres, (1995 Edition replaces 1983 edition).
BISFA--Internationally agreed methods for testing polyester filament yarns, 1983 edition.
Feirabend, Probleme bei der Doppelbrechungsbestimmung an verstreckten Faden aus Polyathylenterephthalat, Melliand Textilberichte, 2:138-144 (1976).
Van Wijk/Vink, Gas Chromatographic Determination of the Alcoholic Part of Polyethylene Terephthalate, ASC, Organ. Coat. Plast. Chem. 32:178-183 (1972).
Feijen Henricus Hubertus Wilhelmus
Hofs Hendrikus Wilhelmus Jacobus
Kiefer Heinrich Johannes Gustav
van den Heuvel Christiaan Jurriaan Maria
van den Tweel Michael Henricus Jacobus
Akzo Nobel N.V.
Edwards Newton
Morris Louis A.
Vickrey David H.
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