Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/12—Stretch-spinning methods
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
• • D—TEXTILES; PAPER
  • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
  • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
  • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
  • D02G3/22—Yarns or threads characterised by constructional features, e.g. blending, filament/fibre
  • D02G3/26—Yarns or threads characterised by constructional features, e.g. blending, filament/fibre with characteristics dependent on the amount or direction of twist
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2321/00—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D10B2321/02—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds polyolefins
  • D10B2321/021—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds polyolefins polyethylene
  • D10B2321/0211—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds polyolefins polyethylene high-strength or high-molecular-weight polyethylene, e.g. ultra-high molecular weight polyethylene [UHMWPE]

Definitions

• the invention relates to a method of manufacturing a multifilament yarn, such as a high performance polyethylene (HPPE) multifilament yarn. More particularly, the invention relates to a method of manufacturing and/or cleaning a multifilament yarn, where no organic spin finish is required.
• HPPE high performance polyethylene
• Multifilament polyolefin yarn is typically manufactured by spinning of a fluid, such as molten polyethylene or a solution (sometimes also referred to as a gel) of polyethylene in a spin solvent, through a spinneret with a multiplicity of spinholes to form filaments. Thereafter, the filaments are cooled and drawn. If a spin solvent is used, then at least some of this solvent is removed by for example evaporation or extraction. Examples of manufacturing processes are meltspinning process (as for example disclosed in EP1445356), solid state process (as for example disclosed in EP1627719) or gelspinning (as for example disclosed in WO 2005/066401 ). A general description is also presented in "Advanced Fibre Spinning Technology", Ed. T.
• multifilament yarn of polyethylene is an electrical isolator and hence tend to build up electro static charge during manufacturing and since the individual filaments of the multifilament yarn is charged similarly (plus or minus), then individual filaments will electro statically repel each other. This means that the multifilament yarn will tend to loosen up instead of forming a unity. Furthermore, in case of filament breakage, the filament ends will tend to move as far away as possible from the main body of the multifilament yarn reducing the quality of the manufactured multifilament yarn by fluff formation or even risk of a loose filament (end) being caught in the manufacturing equipment and hence even requiring production stop to releasing the broken filament.
• organic spin finish is a surface active product and should be avoided for environmental reasons.
• the improvement may for example be one or more of a reduction of the environmental impact, better logistics, reduced handling or another improvement provided by the present invention as discussed below.
• the object of the invention is achieved by a method of manufacturing a multifilament yarn comprising the steps of providing a partially drawn multifilament yarn comprising partially drawn filaments, twisting the partially drawn multifilament yarn to a partially-drawn-twist-level of 4 to 600 turns per meter to form a twisted partially drawn multifilament yarn, and post-twist- drawing the twisted partially drawn multifilament yarn by a draw ratio DR pt of at least 1 .1.
• the partially drawn multifilament yarn may be provided directly from the spinning process in the case where the spin holes of the multifilament spinneret has a contraction zone shaped to provide partially drawing or aligning of the filaments already in the spin holes for example as disclosed in WO 2005/066401 .
• the partial draw multifilament yarn may also be a result of drawing in an airgap after the spinneret.
• the partially drawn multifilament yarn is a solid stage yarn for example after cooling in a quench bath after the spinning.
• the partially drawn multifilament yarn is a gelspun multifilament yarn
• Drawing of the multifilament yarn takes place in multiple steps.
• the twisting of the partially drawn multifilament yarn may be realized inline with a drawing step, or offline not connected with a drawing step.
• inline is herein meant that the partially drawn yarn runs directly between a station where twisting of the partially drawn multifilament yarn is conducted and a station where the multifilament yarn is drawn.
• Offline typically means that a winding step takes place between drawing and twisting.
• Fig. 1 shows schematic flowcharts of methods according to the invention
• Fig. 2 shows schematic flowcharts of a method of manufacturing a HPPE multifilament yarn according to the invention.
• the drawing of the multifilament yarn may be conducted in one or more of the following variations (see Fig. 1 ): a) inline before twisting and followed by offline post-twist-drawing; b) inline before and inline after twisting of the partially drawn multifilament yarn; c) offline before twisting and inline after twisting; d) offline before and offline after twisting, so twisting of the partially drawn yarn takes place in a step separated (in time and/or space) from drawing of the partially drawn multifilament yarn before and after the twisting.
• twisting the partially drawn multifilament yarn and post-twist-drawing is conducted inline.
• the method according to the invention may incorporate more than one post-twist-drawing steps. If more than one post-twist- drawing steps are conducted in the method according to the invention, then it is preferred that twisting of the partially drawn multifilament yarn is conducted inline with at least one of the post-twist-drawing steps, and more preferably twisting of the partially drawn multifilament yarn is conducted inline with all post-twist-drawing steps.
• the method according to the invention may incorporate more than one twisting steps. If more than one twisting steps are conducted in the method according to the invention, then it is preferred that at least one of the twisting steps is conducted inline with a post- twist-drawing step.
• Twisting of the partially drawn multifilament yarn may be conducted on a dedicated (freestanding) equipment or may be combined with into one piece of equipment with one or more of a drawing oven, a quench bath, a winder, an unwinder, a spinning plate.
• twisting the partially drawn yarn is conducted by an inline twister system for example as described in US 6,155,037.
• Inline twister systems described in US 6,155,037 is hereinafter referred to as an Uster twister system.
• this type of equipment allows for introducing a twist to a partially drawn multifilament yarn without having access to the ends of the yarn, this type of equipment is particularly advantageous for retrofitting of existing equipment, such as an existing drawing oven, or an existing winder or unwinder.
• One aspect of the invention therefore concerns a combination of an Uster twister system and a drawing oven, an Uster twister system and a winder, or a Uster twister system and an unwinder.
• twisting the partially drawn yarn is conducted by first winding an untwisted partially drawn multifilament yarn followed by twisting the partially drawn multifilament yarn by unwinding the untwisted partially drawn multifilament yarn using a twisting creel system.
• the twisting creel system is arranged to conduct the unwinding and twisting inline with the post- twist-drawing process wherein the unwinding speed and rotation speed of the twisting creel system is adjusted to the inline post-twist-drawing process.
• the method according to the invention may further comprising the step of tensioning the multifilament yarn in a tensioning station after twisting the partially drawn multifilament yarn and before post-twist-drawing of the partially drawn yarn.
• a tensioning station After twisting the partially drawn multifilament yarn and before post-twist-drawing of the partially drawn yarn.
• drawing of the multifilament yarn typically takes place at an elevated temperature. It is preferred that at least one drawing step takes place at a temperature of above 100°C, and preferably at least one drawing step takes place at a temperature above 120°C. It is preferred that at least one drawing step takes place below the melting point of the multifilament yarn. More preferably, all drawing steps after the spinning takes place below the melting point of the multifilament yarn. Yet more preferably, all drawing steps after spinning takes place at a temperature of at least 5°C below the melting point of the multifilament yarn, and more preferably at a temperature of at least 10°C below the melting point of the multifilament yarn.
• post-twist-drawing takes place in a range between the melting point of the multifilament yarn and 30°C below the melting point of the multifilament yarn, more preferably the post-twist drawing takes place at a temperature at least 5°C below the melting point of the multifilament yarn, such as 10°C below the melting point of the multifilament yarn.
• drawing - and particularly post-twist-drawing - takes place at a temperature below 138°C, preferably at a temperature below 135°C and more preferably at a temperature below 132°C.
• drawing - and particularly post-twist-drawing - takes place at a temperature above 100°C, preferably at a temperature above 1 10°C, more preferably at a temperature above 120°C, and more preferably at a temperature above 130°C.
• monofilaments are understood to mean elongated bodies of indefinite length and with length dimension much greater than their transversal dimensions, e.g. width, thickness or radius, and can have regular or irregular cross-section.
• the monofilaments may have continuous lengths, known in the art as filaments, or discontinuous lengths, known in the art as staple fibers.
• a multifilament yarn according to the present invention is an elongated body comprising a plurality of monofilaments.
• a gel-spun multifilament yarn is herein understood a multifilament yarn manufactured by spinning a solution (sometimes also referred to as a gel) comprising a polymer and a solvent for said polymer.
• the spinning of the solution may be conducted by converting a suspension of polymer and solvent into a solution in an extruder and extruding said solution through a spinneret containing more than one spinning apertures.
• gel-spun polyolefin multifilament yarns which are spun from a solution containing the polyolefin and a solvent for polyolefin, which solvent can be removed from the multifilament yarn after spinning of the yarn by evaporation, like for example naphthenes such as decaline, tetralin or
• the gel-spun multifilament yarns obtained according to the invention are high performance gel-spun multifilament yarns with a tenacity of at least 1 .5 N/tex, preferably at least 2.0 N/tex, more preferably at least 2.5 N/tex or even at least 3.0 N/tex.
• a high performance gel-spun multifilament yarns also have a high tensile modulus (also referred to as Young's modulus), of e.g.
• the multifilament yarns obtained according to the invention have a titer of preferably at least 2 dtex, preferably at least 7 dtex and more preferably at least 8 dtex.
• the titer of the multifilament yarns of the invention are at most several thousand dtex, preferably at most 2500 dtex, more preferably at most 500 dtex.
• the multifilament yarns comprising a plurality of filaments preferably have a titer per filament in the 0.2 - 5 dtex range, preferably 0.5-2 dtex.
• multifilament yarns comprising a plurality of filaments preferably have a titer per filament in the 0.5 - 25 dtex range.
• the multifilament yarn is preferably selected from the group consisting of polyolefin (such as polyethylene and polypropylene), polyester (such as PET, vectran and PLA), polyamide (such as nylon and aramide) and more preferably the multifilament yarn is polyolefin. It is preferred that polyolefin used in accordance with the present invention is polypropylene or polyethylene, more preferably ultrahigh molecular weight polyethylene (UHMWPE).
• UHMWPE ultrahigh molecular weight polyethylene
• HPPE multifilament yarn is herein understood high performance polyethylene, which is yarn comprising drawed polyethylene with a Young's modulus of at least 30 GPa.
• a particularly preferred type of HPPE is gelspun ultra high molecular weight polyethylene (UHMWPE), where the UHMWPE has an intrinsic viscosity (IV) as measured on a solution of UHMWPE in decalin at 135°C, of at least 5 dl/g, preferably at least 10 dl/g, more preferably at least 15 dl/g, most preferably at least 21 dl/g.
• UHMWPE gelspun ultra high molecular weight polyethylene
• the IV is at most 40 dl/g, more preferably at most 30 dl/g, even more preferably at most 25 dl/g.
• Gelspun UHMWPE typically has a Young's modulus of at least 50 GPa.
• the HPPE multifilament yarn has a tenacity of at least 1 GPa.
• the HPPE multifilament yarn comprises at least 90 wt-% UHMWPE filaments and most preferably the HPPE multifilament yarn consists of UHMWPE filaments.
• yarn construction is herein meant a collection of at least two multifilament yarns connected for example by braiding, weaving, knitting, twisting, heat treatment involving partial melting, air entanglement and gluing.
• post-twist-drawing is herein meant the process of drawing a yarn by a factor of at least 1 .1 after twisting of the yarn by at least 4 turns per meter and before optionally converting the yarn into a yarn construction.
• drawing of a yarn construction (such as drawing of a rope construction as described in EP 0 398 434) is a fundamentally different process than post-twist-drawing since drawing of a yarn construction realize the fundamentally different effect of realigning filaments of the construction by creep and does not improve the coherence between the filaments of an individual yarn between the individual filaments in one multifilament yarn of the yarn construction.
• the partially drawn multifilament yarn is twisted to a partially-drawn-twist-level of 10 to 500, and more preferably the partially drawn yarn is twisted to a partially-drawn-twist-level of 12 to 200 turns per meter.
• the optimum partially-drawn-twist-level depends on the titer of the multifilament yarn, the post-twist-drawing ratio, the desired twist level of the multifilament yarn and the optional twist level to be applied to the multifilament yarn after post-twist-drawing.
• the twisted partially drawn multifilament yarn is post-twist-drawing by DR pt of at least 1.5, and more preferably post-twist-drawing by DR pt of at least 2, and most preferably post-twist-drawing by DR pt of at least 3.
• the upper limit of the post-twist-drawing ratio DR pt depends on the condition of the yarn prior to the twisting of the partially drawn yarn, such as for example, the type of polymer, and the draw ratio prior to twisting of the partially drawn yarn, the temperature of the post-twist-drawing.
• the post-twist-drawing ratio is less than 1000; preferably DR pt is at most 100; more preferably DR pt is less than 50; more preferably DR pt is at most 25; more preferably DR pt is at most 10 or less than 10.
• the partially-drawn-twist-level is the number of turns per meter that the partially drawn multifilament yarn has directly after the twisting of the partially drawn multifilament yarn.
• the partially drawn multifilament yarn is twisted to a level where the factor between the partially-drawn- twist-level and the draw ratio, DR pt , of the post-twist-drawing is between 2 - 250 turns per meter, preferably the partially-drawn-twist-level / DR pt is between 2 - 120 turns per meter, more preferably the partially-drawn-twist-level / DR pt is between 2 - 20 turns per meter, such as 5 to 20 turns per meter.
• the twist level of the partially drawn multifilament yarn is sufficiently high that no further twisting of the multifilament yarn is required after post-twist-drawing.
• the partially drawn multifilament yarn may be a homo-yarn or a hetero-yarn.
• homo-yarn is meant that the multifilament yarn consist of filaments having the same composition.
• hetero-yarn is meant that at least one of the filaments of the multifilament yarn has a different composition that other of the filaments of the multifilament yarn.
• at least one of the filaments of the partially drawn multifilament yarn is selected from the group consisting of (coloured or uncoloured) polyester filaments, HD polyethylene filaments, UHMWPE filaments, polypropylene filaments.
• the partially drawn multifilament yarn comprises at least 75 number-% UHMWPE filaments and more preferably the partially drawn multifilament yarn comprises at least 90 number-% UHMWPE filaments.
• the filaments of the partially drawn multifilament yarn consist of UHMWPE filaments, as this provides the strongest and most homogeneous performance of the multifilament yarn.
• Another aspect of the invention concerns a method of removing a spin solvent from a gelspun multifilament polyolefin yarn.
• the method comprising the steps of providing a multifilament yarn comprising polyolefin filaments and a spin solvent, twisting the yarn to a twist level of 10 to 600 turns per meter, and removing at least a part of the spin solvent from the multifilament yarn after twisting the yarn.
• the multifilament yarn provided in the first step may be an undrawn, a partially drawn or post-twist-drawn gelspun multifilament yarn, however, it is preferred that the multifilament yarn is partially drawn or post-twist-drawn.
• the removing of spin solvent is preferably by evaporation or extraction. Evaporation is particularly relevant when the spin solvent is a naphthene such as decaline, tetralin and/or methylcyclohexane.
• Extraction is particularly relevant when the spin solvent comprises paraffin. Twisting of the multifilament yarn before removing at least a part of the solvent from the multifilament yarn allows conducting the conversion into a yarn construction without addition of spin finish to the multifilament yarn. In other words, this aspect of the invention allows removal of the spin solvent from a multifilament yarn in a more environmentally friendly way without jeopardizing the handlabiilty of the yarn, since a spin finish is not required or a smaller amount of spin finish is required. In this embodiment of the invention, it is also preferred to post-twist-drawing the multifilament yarn, however, this is not a requirement. Preferred twisting levels and optional post- twist-drawing levels correspond to the levels as described herein for other aspects of the invention.
• the spin solvent content of the multifilament yarn is already very low before twisting of the partially drawn multifilament yarn.
• the spin solvent of the multifilament yarn during twisting is 10 ppm to 1000 ppm based on the weight of polyethylene and spin solvent.
• the spin solvent of the partially drawn multifilament yarn during twisting is 20 ppm to 500 ppm.
• the spin solvent content of the multifilament yarn during twisting of the multifilament yarn is at least 0.1 wt-% based on the weight of polyethylene and spin solvent, preferably the spin solvent content of the multifilament yarn is at least 0.5 wt-%, more preferably the spin solvent content of the multifilament yarn is at least 2 wt-%, more preferably the spin solvent content of the multifilament yarn is at least 5 wt-%, such as for example at least 10 wt- %.
• the spin solvent content of the multifilament yarn during twisting of the multifilament yarn is below 90 wt-%.
• the amount of solvent removed after twisting of the multifilament yarn depends to a large extent on the content before twisting. Furthermore, the lower the solvent content of the post-twist-drawn multifilament yarn, the higher the effect on coherency of the twisting before removing the solvent from the yarn. In one
• At least 10 wt-% of the spin solvent present during the twisting is removed after twisting the multifilament yarn and preferably at least 90 wt-% of the spin solvent present during the twisting is removed after twisting the multifilament yarn. Most preferably at least 99 wt-% of the spin solvent present during the twisting is removed after twisting the multifilament yarn. It should be observed that if more twisting steps are utilized, then the solvent content during twisting is the solvent content during the first twisting step. The fraction of solvent removed from the multifilament yarn after twisting depends to some extent on the amount present before twisting. It is preferred that 100% of the solvent is removed, but since traces of solvent may stay in the multifilament yarn, in one embodiment at most 99.999% of the solvent is removed.
• the removed spin solvent is preferably collected and recycled by known means.
• the process further comprises a post-twist-drawing step.
• DR pt of at least 1.1 to form a HPPE multifilament yarn. More preferably the post-twist drawing draw ratio is at least 1.5, and even more preferably DR ⁇ is at least 2, and most preferably by a DR pt of at least 3.
• the upper limit of the post-twist-drawing ratio DR PT depends on the condition of the yarn prior to the twisting of the partially drawn yarn, such as for example, the type of polymer, and the draw ratio prior to twisting of the partially drawn yarn, the temperature of the post-twist-drawing.
• the post-twist-drawing ratio, DR PT is less than 1000; preferably DR pt is at most 100; more preferably DR PT is less than 50; more preferably DR pt is at most 25; more preferably DR PT is at most 10 or less than 10.
• One aspect of the invention therefore concerns a method of manufacturing a gelspun HPPE multifilament yarn without adding a spin finish.
• the flowchart in Fig. 2 indicates this method. The method comprising the steps of providing (2) a solution of 3-25 wt-% UHMWPE in a spin solvent (based on UHMWPE and spin solvent in the solution).
• the solution may for example be provided by converting a suspension of UHMWPE and spin solvent in an extruder, spinning (4) the solution through a spinneret having at least two spin holes, quenching (6) the solution in a quench bath, and drawing (7) to form a solid multifilament yarn comprising partially drawn UHMWPE filaments.
• twisting (12) the partially drawn multifilament yarn to a twist level of 2 to 600 turns per meter to form a twisted partially drawn multifilament yarn
• post-twist-drawing (13) the twisted partially drawn multifilament yarn by a draw ratio DR pt of at least 1 .1 to form a HPPE multifilament yarn
• twisting, removal of spin solvent and post-twist-drawing are conducted without adding a spin finish to the multifilament yarn.
• At least a part of the spin solvent is removed during the process by evaporation or extraction. Twisting of the partially drawn multifilament yarn may be conducted inline, offline or a combination of inline and offline with drawing conducted prior to twisting.
• Twisting of the partially drawn multifilament yarn may be conducted inline, offline or a combination of inline and offline with post-twist-drawing. It was found to be highly advantageous to conduct drawing prior to twisting offline with the twisting and to conduct twisting inline with at least a part of the post-twist-drawing as this allows for good traceability and compact process equipment.
• the methods according to the present invention are particularly advantageous in relation to preparation of polyethylene yarn to be used in medical applications, medical repair products, implants and medical devices, as the methods allows for preparation of polyethylene yarn without the use of a spin finish and particularly an organic spin finish, which organic spin finish typically is not desired inside the body or in contact with the body.
• Example of medical applications are medical components, like for example vascular prostheses, joint arthroplasty, orthopedic and spine implants, for example meniscus implants, surgical sutures, meshes for example hernia meshes, fabrics, woven or non-woven, textiles, sheets, tapes, ribbons, bands, artificial joints, cables such as trauma fixation cables, sternum closure cables, prophylactic or per prosthetic cables, long bone fracture fixation cables, small bone fracture fixation cables, tube-like products for example ligament
• the methods according to the present invention are also advantageous in relation to preparation of polyethylene yarn to be used in other end-use products and applications like ropes, cables and cords, mooring lines, fishing lines and fishing nets, sports equipment, impact and abrasion resistant products and ballistic-resistant products.
• Example 1 Preparation of HPPE yarn with drawing inline before twisting.
• Fig. 1 a shows a flow diagram of a method of preparation of a polyolefin multifilament yarn where drawing inline with twisting is conducted before twisting. After twisting, the partially drawn multifilament yarn is wound on a bobbin before (at a later time) conducting offline post-twist-drawing.
• the twisting may be conducted in conjunction with winding of the partially drawn multifilament yarn in a combined twisting and winding unit, such as for example available from the companies Alma-Sauer, Dietze & Schell, Galan, and Barmag.
• the twisting and winding may also be conducted in two separate steps in which case the twisting for example may be conducted in a process and equipment as disclosed in US 6,155,037 and the winding for example may be conducted on a precision cross winder, for example from SSM, Dietze & Schell , Comoli, Leesona, Georg Sahm GmbH, Oerlikon, and Barmag.
• the winded and twisted partially drawn yarn is later (i.e. offline) post-twist-drawing. This corresponds to the process indicated in Fig. 1 a, where in addition to the drawing (8) conducted inline before twisting (12), further offline drawing (10) may be conducted prior to the inline drawing (8).
• Example 2 Preparation of HPPE yarn with drawing inline before and after twisting.
• Fig. 1 b shows a flow diagram of a method of preparation of a polyolefin multifilament yarn where drawing inline with twisting is conducted before as well as after twisting.
• the twisting may be conducted with a twisting unit of the type for example disclosed in US 6,155,037 where a running yarn is twisted inline during transfer through the twisting unit.
• one large twisting step is utilized to achieve the desired twist level.
• multiple smaller steps of twisting such as 2, 3, 4, 5, 6, 7, 8, 9 or 10 twisting steps
• the multiple smaller drawing steps may be arranged in between multiple smaller drawing steps or in groups of drawing steps between drawing steps.
• one or more offline drawing steps may optionally be utilized before (10) or after (16) the inline drawing and twisting steps (8, 12, 14).
• Example 3 Preparation of HPPE yarn with drawing inline after twisting.
• Fig. 1 c shows a flow diagram of a method of preparation of a polyolefin multifilament yarn where drawing inline with twisting is conducted after twisting.
• a partially drawn multifilament yarn is prepared by drawing (10) for example in a first drawing oven the as-spun multifilament yarn and thereafter winding the partially drawn multifilament yarn on bobbin for example on a Twinstar precision cross winder from Georg Sahm GmbH.
• the partially drawn multifilament yarn is twisted and post-twist-drawing.
• the twisting preferably takes place on a combined twist and unwinder apparatus such as for example a twisting creel available from for example Alma-Sauer, Dietze & Schell, Galan, and Barmag.
• a separate unwinder may be combined with a twisting unit of the type for example disclosed in US 6,155,037.
• the yarn may optionally be further drawn offline (16).
• the advantage of this embodiment is, that the unwinding and twisting can be finely tuned with the drawing process and allow for rapid start and stop in relation to yarn breakage. Furthermore, traceability is easier to handle as compared to the drawing variation of Example 4 since less offline processes are involved.
• Example 4 Preparation of HPPE yarn with drawing offline before and after twisting.
• Fig. 1 d shows a flow diagram of a method of preparation of a polyolefin multifilament yarn where drawing is conducted offline before and after twisting.
• the partially drawn multifilament yarn is prepared as described in Example 3 by drawing (10) for example in a first drawing oven the as-spun multifilament yarn and thereafter winding the partially drawn multifilament yarn on bobbin for example on a Twinstar precision cross winder from Georg Sahm GmbH.
• the partially drawn multifilament yarn is thereafter at a later time twisted on a twist and rewind equipment for example available from SSM, Dietze & Schell , Comoli, Leesona, Georg Sahm GmbH, Oerlikon, and Barmag.
• Bobbins of partially drawn UHMWPE yarn were prepared by preparing a solution of UHMWPE in decalin in an extruder, spinning the solution through a spinneret having 200 spin holes, quenching in a quench bath, partially drawing the as-spun yarn and removing more than 99% of the spin solvent from the yarn as compared to spin solvent content of the solution. No spin finish was provided during the process. Finally, the yarn was wound on bobbins each holding about 9000 m.
• Example 7 Preparation of HPPE yarn utilizing drawing offline before and after twisting
• Bobbins of partially drawn UHMWPE yarn prepared in Example 5 were subjected to the offline drawing process as described in Fig. 1 d).
• a twist level of 16 turns per meter was provided by unwinding using a ring-twister, parallel winding and a separate step of rewinding using cross winding.
• the bobbins of partially drawn and twisted UHMWPE yarn were hereafter drawn using an offline post-twist-drawing ratio of 4. No spin finish was provided during the twisting or post-twist-drawing processes.

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• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
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• 2014
  • 2014-01-27 KR KR1020157020134A patent/KR20150110550A/ko not_active Application Discontinuation
  • 2014-01-27 BR BR112015017564A patent/BR112015017564A2/pt not_active IP Right Cessation
  • 2014-01-27 CA CA2897906A patent/CA2897906A1/en not_active Abandoned
  • 2014-01-27 EA EA201500766A patent/EA201500766A1/ru unknown
  • 2014-01-27 JP JP2015554180A patent/JP2016508549A/ja active Pending
  • 2014-01-27 EP EP14701413.8A patent/EP2948579B1/de not_active Not-in-force
  • 2014-01-27 MX MX2015009421A patent/MX344520B/es active IP Right Grant
  • 2014-01-27 CN CN201480005797.2A patent/CN104955992B/zh not_active Expired - Fee Related
  • 2014-01-27 WO PCT/EP2014/051534 patent/WO2014114793A2/en active Application Filing
  • 2014-01-27 US US14/762,212 patent/US20150361588A1/en not_active Abandoned
  • 2014-01-27 EP EP16159435.3A patent/EP3051010A1/de not_active Withdrawn
• 2016
  • 2016-03-21 HK HK16103250.1A patent/HK1215287A1/zh unknown

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