JP4440106B2 - Manufacturing method of monofilament-like product - Google Patents

Abstract

The invention relates to a process for making a monofilament-like product from a precursor containing at least one strand of a spun yarn made from polyolefin staple fibres, comprising the steps of a) exposing the precursor to a temperature within the melting point range of the polyolefin for a time sufficient to at least partly fuse adjacent fibres and b) simultaneously stretching the precursor at a draw ratio of at least 1.0. The invention further relates to a monofilament-like product obtainable by said process showing improved abrasion resistance, and to the use of said monofilament-like product for making various semi-finished and end-use products.

Description

  The present invention relates to a process for producing a monofilament-like product from a precursor comprising at least one strand of polyolefin fibers, the process comprising: a) a sufficient amount of polyolefin for a time sufficient to at least partially melt adjacent fibers. Exposing the precursor to a temperature within the melting range, and b) simultaneously stretching the precursor at a draw ratio of at least 1.0. The invention further relates to a monofilament-like product obtainable by said method and to the use of said monofilament-like product for the production of various semifinished and final products.

  Such a method is disclosed in EP0740002 B1. This specification describes a method for producing fishing lines from yarns of filament material. In this method, a braided fishing line, a twisted fishing line, or a twisted fishing line composed of yarns of gel-spun polyolefin filaments is melted at least partially to a temperature within the melting point range of the polyolefin. The fishing line is stretched at a draw ratio in the range of 1.01 to 2.5 at the same time. The yarn applied in this method is a continuous multifilament yarn, more specifically such yarn is produced, for example, by Spectra (ultra high molecular weight polyethylene (UHMwPE), so-called gel spinning. (Registered trademark) or Dyneema (registered trademark).

  In general, fishing lines are monofilaments made of synthetic polymers and have a round and solid structure that can be handled suitable for bait casting, spinning, and spin casting. In general, these monofilament fishing lines have hard properties and a smooth surface that combine to reduce casting resistance and can be cast far away with improved release from the fishing reel. Braided yarn is not suitable for fishing lines. This is because it tends to fray the ends of the yarn, has the risk of water ingress, has an outer surface that is susceptible to tearing and entanglement, and has an opaque white color that is well visible in water. The method disclosed in EP0740002 B1 makes it possible to produce monofilament fishing lines from braided or twisted yarns made of polyolefin multifilament yarns. This fishing line does not have the above-mentioned drawbacks of braiding.

  The disadvantage of the process described in EP 0 740 0002 B1 is that the resistance to fracture is insufficient when the product obtained thereby is exposed to wear conditions.

  The object of the present invention is therefore to provide a method for producing a monofilament-like product which does not have the above drawbacks.

The object is to produce a monofilament-like product from a precursor comprising at least one strand of polyolefin fibers, a) a range of melting points of the polyolefin for a time sufficient to at least partially melt adjacent fibers. and exposing the precursor to a temperature of the inner, b) simultaneously, the precursor, and a step of stretching at least 1.0 draw ratio, the strand, Ri spun yarn der composed of a polyolefin staple fibers Realized by the present invention using a process wherein the polyolefin is ultra high molecular weight polyethylene .

  In the process according to the invention, the monofilament-like product can be produced, for example, from a polyolefin twisted or braided structure. This product has improved wear resistance, expressed as the number of cycles to failure, as measured in the test described in “Materials and Methods”.

  The monofilament-like product obtained with the process according to the invention also exhibits a surprisingly high tensile strength, which is significantly higher than the original spun yarn or a twisted yarn made from such a spun yarn and used as a precursor. Further, the resulting monofilament-like product has a comfortable feel or feel, can be easily handled and can be easily knotted. In addition, this product exhibits surprisingly high knot strength and knot strength efficiency. Another advantage of the method according to the invention is that the degree of melting can be easily changed and controlled and a product with an adjusted characteristic profile can be obtained. Yet another advantage is that the coating composition can be effectively applied to the resulting monofilamentary product with additional process steps.

  In the process according to the invention, the monofilament-like product is produced from a precursor comprising at least one strand of polyolefin fibers. A monofilament-like product has an appearance and feel that is more like a monofilament than a multifilament yarn or string, but is actually a product that consists of at least one strand that contains a large number of fibers usually less than about 50 micrometers in diameter. It is understood that. This monofilament-like product has a diameter that varies within a wide range, for example from about 0.1 to 10 millimeters. As used herein, a precursor is understood to be an article of indeterminate length comprising at least one strand of polyolefin fiber, which is used as a feed or starting material. Suitable precursors can be, for example, in the form of braids, twisted yarns, cords or ropes, including multiple strands, but can also be single strand yarns. A strand of polyolefin fiber can be understood as a thread-like fiber product mainly containing polyolefin fibers of 50% by mass or more.

  The method according to the present invention includes exposing the precursor to a temperature within the melting point range of the polyolefin for a time sufficient to at least partially melt adjacent fibers. The conditions for this melting step are selected such that the temperature and time of exposure are sufficient to soften the polyolefin fibers and at least partially melt them within the particular structure being applied. The melting point range of polyolefin is a temperature range between the melting point peak of non-oriented polyolefin and the melting point peak of fixed highly oriented polyolefin fiber, which is determined by DSC analysis using a scanning speed of 20 ° C./min. In general, for UHMwPE fibers having a melting point range of 138-162 ° C, this temperature is preferably in the range of about 150 ° C to about 157 ° C. The residence time during which the precursor is exposed to the melting temperature can vary over a wide range, but is generally in the range of about 5 seconds to about 1500 seconds. Although higher temperatures tend to accelerate the melting process, care should be taken not to apply temperatures that are too high. This is because an excessively high temperature may reduce the strength of the product due to partial melting or a molecular relaxation effect.

  During the melting process, the appearance of the precursor changes from an initial opaque white to a translucent milky white or almost transparent product surface appearance, depending on the degree of melting and the type of precursor material. The light transmission of the product increases as the degree of melting between the fibers increases. Such translucency or light transmission is a distinct advantage for use as an underwater fishing line.

  For a monofilament-like product with little fraying at the ends, it is sufficient that the outer layer of the fiber is at least partially melted, as can be seen by the increased light transmission. However, a higher degree of melting, such as melting which also binds the inner fibers of the precursor or strand, is preferred to make a product with higher wear resistance and higher bending stiffness, i.e. more monofilamentous properties . The degree of melting can be adjusted by changing the exposure temperature and / or the exposure time in the process of the present invention.

  The degree of melting can be determined for the resulting product, for example, by evaluating the appearance with the naked eye or using an optical or electron microscope, or by measuring mechanical properties such as strength or stiffness. it can. Another possibility is to measure the absorption and absorption rate of a colored liquid, for example from a marker, as described in EP 0 740 0002 B1. The degree of melting can also be obtained from a test where the loaded product is worn on a metal rod and the number of movements until the monofilament product is broken down into its constituent filaments.

  In a particular embodiment of the method, the degree of melting is very low or even difficult to measure in the product. Surprisingly, it has been found that in products drawn at elevated temperatures, the tensile strength is significantly improved compared to its precursor. However, the wear resistance is only slightly improved. Accordingly, the present invention draws a braided or twisted structure comprising at least one strand of a spun yarn of polyolefin staple fibers at a draw ratio of at least 1.1 while exposing it to a temperature within the melting point range of the polyolefin. Also related to how to do. In the product obtained in this way, the tensile strength is improved, but the bending properties are still quite similar to the starting structure.

  The method according to the present invention also includes the step of simultaneously stretching the precursor at a draw ratio (also referred to as a draw ratio) of at least 1.0. A strength reduction of the product is prevented by subjecting the precursor to a stretch ratio of at least 1 during thermal exposure. When the draw ratio is 1.1 or more, the tensile strength tends to improve. Surprisingly, it has been found that the strength of the product is significantly higher than the strength of the precursor or the strands contained therein. Beyond a certain draw ratio, this effect may be leveled off, or the strength may be reduced as a result of partial damage or breakage of the fiber. Furthermore, the higher the draw ratio, the smaller the resulting product titre. Thus, the maximum draw ratio depends on the precursor and its fiber type and is generally about 50 at maximum. Preferably, the draw ratio is 1.1 to 40, 1.2 to 25, more preferably 1.3 to 10, and even more preferably 1.4 to 5.

  Preferably, the product obtained after step b) is cooled while maintaining the tension. This has the advantage that the fiber level and the molecular level orientation within the fiber are better retained in the product obtained during melting and drawing. Such tension can be obtained, for example, by winding the product into a package after the preceding steps of the method.

  In the method according to the present invention, at least one strand in the precursor is a spun yarn made of polyolefin staple fibers. That is, the spun yarn includes at least 50% by mass of polyolefin staple fiber. In general, the yarn can be made of continuous filaments, staple fibers, or combinations thereof. Natural fibers can be divided into two categories: short staple fibers (such as cotton with a normal staple or filament length of 15-60 mm) and long staple fibers (with a normal staple length of 40-200 mm). , Something like wool). Synthetic fibers are first made as continuous filaments. This can then be converted to staple fibers by cutting or chopping methods. Cutting generally results in a rectangular filament distribution (all filaments have approximately the same length). However, the improved system can change the filament length distribution to some extent. In cutting, staple fibers are generally obtained in which the filament length is closer to a Gaussian distribution. In the shredding method, the filament is stretched between several sets of rollers moving at different speeds until it breaks.

  Staple fibers can be made into yarn through a process commonly referred to as spinning, in which strands of parallel fibers are pulled and twisted. For this reason, yarns made from staple fibers are called spun yarns.

  The industrial spinning process includes the following basic process steps: loosening, carding, drawing and spinning. The loosening is, for example, separating packed staple fibers and washing them as necessary. Carding is the further loosening and separation of the fibers, for example by passing between rotating drums covered with needles. This gives a thin web of fibers that are partially parallel. This web is formed into rope-like strands, often called slivers. Combing is then applied to increase fiber orientation and remove small fibers. During stretching, the sliver is stretched in one or more steps. In order to obtain a uniform fiber density, several slivers consisting of the same or different staple fibers can be blended. Mixing staple fibers during the carding stage can also produce yarns containing blends of different natural and / or synthetic fibers. Before being fed to the spinning machine, the sliver can be further stretched with a slight twist, which is called roving. During spinning, the sliver or roving is further stretched and twisted to bind the overlapping fibers and wind this yarn around the bobbin. These packages of wound yarn are conical or cylindrical and are usually simply called packages.

  The spinning process described above results in a single strand strand. This is also called a single yarn. Depending on the direction of twist applied, such yarns are often referred to as S or Z yarns. Single strand twisted yarns are generally quite "active", i.e., with insufficient tension, tend to twist, tangle, tilt or curl around themselves. In order to reduce this “activity”, ie to obtain a calm or balanced yarn that can be satisfactorily processed, for example, in textiles, the industry generally has two strands of single yarn in an additional step. It is accepted that more or more need to be combined. Such a combination step is commonly referred to as mash twisting. For example, a twisted twin yarn can be made by combining two single strand Z yarns with S twist or by twisting Z and S yarns together. There is a possibility that the mash yarn obtained in this way is stronger and more uniform than the single strand yarn.

  The spun yarn applied to the method according to the invention comprises at least 50% by weight of polyolefin staple fibers. The spun yarn can further comprise up to 50% by weight of one or more staple fibers, such as natural or synthetic fibers, to make a blended yarn. Suitable examples of such second staple fibers include wool, polyolefin, acrylic, polyester, or polyamide including aromatic polyamide fibers.

  In a special embodiment of the method according to the invention, the spun yarn comprises a certain amount of staple yarn made of a thermoplastic polymer having a lower melting range than the polyolefin staple fibers. The advantage is that during step a) additional thermal bonding can take place. This possibility arises when using spun yarns in the method according to the invention, since making spun yarns is easier and more economical than making spun multifilament yarns. Examples of suitable thermoplastic polymers include copolymers of at least one alpha olefin and other monomers, such as LLDPE, or ethylene acrylic copolymers. The effective amount of such staple fibers can be determined experimentally and is generally about 5-25% by weight.

  In another particular embodiment of the invention, the main component of the spun yarn is not a polyolefin staple fiber, but consists of a high strength, high modulus filament yarn that has higher heat resistance than polyolefin and cannot itself be thermally bonded. Staple fiber. For example, aromatic polyamide yarn such as Kevlar® or Twaron®, liquid crystal polyester yarn, or polybenzoxazole or polybenzothiazole yarn. Such spun yarns further comprise up to 50% by weight of staple yarns of relatively low melting range made of thermoplastic polymers, for example polyolefin staple fibers having a melting point of less than 200 ° C. Examples of suitable thermoplastic polymers include copolymers of at least one alpha olefin and other monomers, such as LLDPE, or ethylene acrylic copolymers. The advantage of this embodiment is that the thermal bonding takes place during step a). On the other hand, if there is no fiber having a low melting point, a monofilament-like product cannot be produced from such high-heat-resistant, high-strength, high-modulus filament yarn by exposing to heat while drawing. The effective amount of such thermoplastic, hot melt staple fibers can be determined by experiment and is generally about 5-25% by weight. A monofilament-like product based on spun yarn containing aromatic polyamide staple fibers and hot-melt staple fibers produced by this method has both high strength, high wear resistance and high heat resistance.

  The spun yarn and staple fiber can further contain conventional additives such as stabilizers, colorants, mineral particles, sizing agents, and the like.

  Selection of other staple fibers such as type, length, titer (dpf), whether this staple fiber can be melted with polyolefin staple fibers at the applied temperature and time conditions, and / or selection of additives is: Primarily determined by the desired final properties. This selection can be made by a person skilled in the art using general knowledge or routine experimentation.

  Preferably, the spun yarn used in the method according to the invention comprises at least 60%, 70%, 80% or 90% by weight of polyolefin staple fibers. This is because the mechanical properties of the resulting product can be improved. For this reason, it is most preferable that the spun yarn used contains substantially only the staple fiber.

  Staple fibers obtained from various polyolefin yarns can be selected as staple fibers for use in the method according to the invention. Particularly suitable polyolefin yarns are made from ethylene or propylene homopolymers and copolymers. Furthermore, the polyolefins used can contain small amounts of one or more other monomers, in particular other alpha olefins. Good results are obtained when linear polyethylene (PE) is selected as the polyolefin. Linear polyethylene is understood here as polyethylene having side chains of less than 1 per 100 carbon atoms, preferably less than 1 per 300 carbon atoms. The side chains or branches are usually those containing at least 10 carbon atoms. The linear polyethylene may further comprise up to 5 mol% of one or more comonomers, for example alkenes such as propylene, butene, pentene, 4-methylpentene or octene. In addition to polyolefins, the fibers can contain small amounts of solvents or additives commonly used for such fibers, such as antioxidants, spin finishes, heat stabilizers, colorants, and the like.

  Preferably, the polyolefin fibers, especially polyethylene fibers, have an intrinsic viscosity (IV) higher than 5 dl / g. Due to their long molecular chains, polyolefin fibers having such IVs have very good mechanical properties such as high tensile strength, high elastic modulus and high breaking energy absorption. This is also the reason why the polyolefin is preferably a polyethylene having an IV of more than 10 dl / g. IV was measured according to the method of PTC-179 (Hercules Inc. Rev., April 29, 1982) in decalin at 135 ° C. at a dissolution time of 16 hours, and the antioxidant was DBPC in a 2 g / l solution. Extrapolate the viscosity at different concentrations to zero concentration. Such high viscosity polyethylene is often referred to as UHMwPE. UHMwPE filament yarn can be prepared by spinning a solution of UHMwPE to make a gel fiber and drawing the fiber before, during, and / or after partially or completely removing the solvent. That is, for example, European Patent Application No. 0205960 A specification, International Publication No. 01/73173 A1 pamphlet, Advanced fiber spinning technology, T.W. Edited by Nakajima, Woodhead Publ. According to the so-called gel spinning method described in Ltd. (1994), ISBN 185573 182, and the literature cited therein.

  It is preferred to select UHMwPE staple fiber because it has both high strength and low relative density. More specifically, the spun yarn used in the method according to the present invention comprises UHMwPE staple fibers made from a multifilament UHMwPE yarn by a chopping method. This is because such a staple has a wider fiber length distribution, so that a yarn with improved mechanical properties can be obtained.

In a special embodiment, the spun yarn used is a single strand spun yarn. In other embodiments, single strand spun yarns described in unpublished copending applications are used in the method according to the invention. This single strand spun yarn is obtained from a continuous polyolefin multifilament yarn of at least 50% by weight, having a tensile strength of at least 16 cN / dtex, a tensile modulus of at least 700 cN / dtex and a denier per filament of fiber of 18 dpf or less. Made from staple fiber. This staple fiber has an average fiber length of 40 to 180 mm and is substantially free from crimps. The spun yarn has an α twist coefficient of 40 to 100 t. m ⁻¹ . ( ^M / g) It has a twist level characterized by being ^-1/2 . This staple fiber is preferably obtained from a highly oriented polyolefin fiber based on, for example, ultra high molecular weight polyethylene (UHMwPE). The advantage of this method is that EP 0 740 0002 A1, starting from multifilament yarns with a relatively low titer, for example 10-100, preferably 15-50 dTex, and a translucent monofilament-like product with low comparative density. It can be produced at a higher overall production rate and lower overall cost than the methods known in the specification. The product obtained by this method is particularly suitable for medical applications such as surgical sutures.

The α twist coefficient characterizes the twist level of the yarn by the Koechlin equation: T = α (Nm) ^1/2 . Where T is the twist level expressed in revolutions per meter (tm ⁻¹ ) and Nm is the metric count (1000 / tex, or m / g). This twist factor is also referred to as the (metric) twist factor, or twist multiplier. http: // www. fiber2 fashionion. com / GLOSSARY / glossary7. htm. See example in Preferably, the twist factor is between 60 and 100, 65 and 90, or in particular between 70 and 85.

  This single-strand spun yarn shows little activity and is sufficiently settled, so that the next processing can be performed without the need to first make a twisted yarn. The staple fiber in the single strand spun yarn has a filament density of 18 denier (dpf) or less per filament, preferably 14 dpf or less, more preferably 10 dpf or less, further preferably 6 dpf or less, and most preferably 4 dpf or less. It was obtained from Since a predetermined minimum number of fibers is required in the cross section in order to obtain a yarn having sufficient bondability, the spun yarn may become thin when the fiber linear density is low. Further, when the fiber linear density is lowered, the tensile strength of the spun yarn is increased with a constant yarn titer. Considering the production efficiency of the fiber, the linear density is preferably at least 0.2, 0.3 or at least 0.5 dpf. Starting from finer spun yarns has the advantage that thinner monofilament-like products can be produced in a more economical manner.

  The single-strand spun yarn used in the method according to the present invention comprises polyolefin staple fibers that are substantially free of crimp. The fibers are not textured or are only slightly textured. Crimp is a measure of fiber undulation and is expressed as the difference between the length of a straightened or fully stretched fiber and the length of the crimped length, i.e., when there is virtually no external constraint. The As used herein, substantially free of crimp is understood to mean that the staple fiber length in the unconstrained state is at least 80% of the straightened length. Preferably, the crimp length is at least 90% of the straightened length, more preferably at least 95%. It is understood that substantially free of crimp does not include further permanent crimp. For example, UHMwPE staple fibers can include some degree of crimp introduced during the making of staples, but this disappears when the tensile force that may occur during spinning is applied to the fibers, for example. Crimp is not permanent.

  In the method according to the present invention, at least one strand in the precursor is a spun yarn made of polyolefin staple fiber. The precursor is a single strand of other staple fibers and / or continuous filaments to reach monofilament-like products with different degrees of melting between and within the strands, and to reach different mechanical properties and appearance and feel. Alternatively, a plurality of strands can be included. Those skilled in the art can make such different types using general knowledge or routine experimentation. All strands in the precursor are preferably spun yarns based on polyolefin staple fibers. This is because the degree of melting, that is, product characteristics can be significantly changed.

  The method according to the invention can be carried out with precursors of various structures, for example, a braided structure or a twisted structure. Preference is given to using precursors with twisted strands, ie plaid [folded] and twisted strands. This has the advantage that the precursor can be produced more easily and economically. In addition, the resulting product has excellent performance, particularly surprisingly good fracture resistance during wear testing.

  The method according to the present invention may further comprise a step of pretreating the precursor or one or more strands therein prior to step a) in order to promote adhesion between the fibers during the melting step. it can. Such pretreatment steps may include applying components or compositions to the precursor, washing off the precursor, i.e. washing off surface components such as spin finishes, or applying a high voltage plasma or corona treatment. it can.

  In one embodiment, the precursor is for polyolefins such as an effective amount of mineral oil (eg, heat transfer grade mineral oil having an average molecular weight of about 250-700), vegetable oil (eg, palm oil), or preferably non-volatile paraffin. It is pretreated by applying a solvent such as dipping or wetting. This pretreatment step can be performed at room temperature or can be performed by raising the temperature to a temperature lower than the temperature range in which the polyolefin fibers are melted.

  In another embodiment, the pretreatment includes applying a coating composition to the precursor. The composition can be a solution or dispersion of a polymer that promotes fiber-to-fiber adhesion when exposed to higher temperatures in the melting step, or otherwise improves performance. In a preferred embodiment, the precursor is coated with a polyurethane composition, such as a dispersion of film-forming polyurethane. Such compositions can further include components that help improve the abrasion resistance or cut resistance of the monofilament-like product. Examples of components that improve cutting resistance include fine particles having high surface hardness, such as mineral particles, ceramic particles, glass, and metal. The coating composition can further include other additives such as colorants and stabilizers.

  The method according to the present invention may further comprise the step of applying a coating composition to the product after steps a) and b) to form a coating layer. Such coating compositions are representative spin finishes that allow easier handling and processing of the product in subsequent operations, compounds or compositions that control adhesion during subsequent manufacture of composites containing the product. Or a binder composition that further improves the integrity and strength of the product. A typical example of the latter is a polyolefin-based binder composition such as polyurethane or ethylene acrylic copolymer. The coating composition can be applied as a solution or dispersion. Such compositions can further include components that further improve the abrasion resistance or cut resistance of the monofilament-like product. Examples of components that improve cutting resistance include fine particles with high surface hardness, such as various mineral particles or ceramic particles. The coating composition can further include other additives such as colorants and stabilizers.

  Application of the coating composition in the method according to the invention has been found to be relatively easy and effective compared to methods using continuous filament yarn. It can be seen that the product obtained after steps a) and b) accepts such coatings more easily, especially if only some of the fibers on the product surface are melted.

  The invention also relates to a product obtained by the method according to the invention, i.e. a monofilament-like product comprising spun yarns of polyolefin staple fibers which are at least partly melted. This product has a unique structure and combines several excellent properties. Although this product has a monofilament translucent appearance, its feel is different from polyolefin monofilament or the monofilament-like product described, for example, in EP 0 740 0002 B1. The monofilament-like product of the present invention has a surprisingly high breaking resistance during the wear test and can be easily knotted, and the knotted product has a high strength retention. Monofilament-like products also have surprisingly high tensile strength, higher than the strength of the starting spun yarn in the precursor. Usually, the tensile strength of the monofilamentary product of the present invention is at least 10 cN / dtex, preferably at least 15, 20 or even 25 cN / dTex. Such high strength is typically found in precursor-based products with relatively high amounts of spun yarn based on UHMwPE staple fibers.

  The monofilament-like product obtained by the method according to the invention can vary in linear density, also called titer, in a wide range, for example 10 to 15000 dTex. In general, the product titer is 30 to 2500 dtex. Products with low titers are suitable for use as sutures and the like. Considering applications such as fishing line or protective clothing, the titer is preferably 100 to 1600 dTex, more preferably 200 to 1200 dTex.

  The present invention further provides the monofilament form of the present invention for producing various semi-finished and finished products, such as fishing lines, sutures, fabrics, strings and ropes, composite yarns, and their use, for example, in cut resistant articles. Also related to product use.

  The invention also relates to semi-finished products and final products comprising the monofilamentary product of the invention.

  The invention is further illustrated by the following examples and comparative experiments.

Material and method Multifilament UHMwPE yarn with 1760 dTex, tensile strength of 28 cN / dTex, tensile modulus of 910 cN / dTex, and denier per filament of fiber of about 1 dpf, Dyneema® 1760SK60 (made by DSM, The Netherlands) Staple fibers were produced from the high-performance fibers by, for example, the cutting method described in EP-A-0445872. The average length of the staple fiber was about 80 mm. Next, this staple fiber was spun into a single strand yarn using a long staple fiber type NSC apparatus. The resulting yarn had a count of about Nm44 (about 225 dTex) and the applied twist level was equivalent to about 80 in terms of Koechlin's law). The spun yarn showed little activity. This was demonstrated by cutting a length of 100 cm, holding only one end and holding it vertically, and observing little tendency to kink. The tensile strength was about 15.0 cN / dTex, the tensile modulus was about 153 cN / dTex, and the elongation at break was about 4.3%. This material is hereinafter referred to as SSSY.

  Tensile strength (or strength) (and tensile modulus) is measured with multifilament and spun yarns and monofilament products using a standard gauge distance of the fiber of 500 mm, a crosshead speed of 50% / min, and an Instron 2714 clamp. Defined and measured as specified in ASTM D885M. To calculate the strength, the measured tensile force is divided by the titer determined by measuring the weight of 10 meters (or another length) of fiber. The elongation is the measured elongation at break and is expressed as a percentage of the original length after clamping the specimen.

  The nodule strength is determined by measuring the strength of a test piece containing a Palomar knot. Palomar knots are a universal connection method recommended for joining fishing lines to swivels, snaps or hooks. Pass the doubled end of the specimen through the hole in the hook and make a simple knot. The hook is then tightened through the loop.

  Nodule strength efficiency is calculated as the relative value (%) of the nodule strength measurement to the tensile strength measurement.

  Abrasion resistance was measured according to a procedure based on the test described in ASTM D3108 for measuring yarn wear life. For this purpose, the yarn wear life measuring apparatus described in ASTM D3108 was modified so that one end of the test sample was fixed to an electric rotating eccentric crank or cam and a load was applied to the other end. During the test, the sample was rubbed against the ceramic hole, and the number of cycles until the sample became defective (breaks) was determined. The numerical values shown are average values of at least 5 tests.

(Comparative Experiment A)
As a precursor (supply) material, a braided structure comprising a multifilament gel spun UHMwPE yarn having a titer of 224 dTex, a tensile strength of 39 cN / dTex, a tensile elastic modulus of 1250 cN / dTex, and a denier per filament of fiber of about 1 dpf Was used. The braid included 8 strands of the yarn (indicated as 8 × 224 / 7.5), with a tightening expressed in picks per centimeter at a medium tightening of 7.5. 1).

  As a pretreatment, the braid was passed through a liquid paraffin bath and passed between nonwoven fabrics to wipe off excess oil. The paraffin content was calculated to be about 11% by weight by measuring the mass increase at this step. Next, the braid was guided from the first driving roll into a furnace maintained at a constant temperature of 153.5 ° C. at a constant speed of 10 m / min. The braid was led to the second drive roll at the exit of the furnace. The speed of the second roll was adjusted to add a draw ratio of 1.9 and a draw speed of 0.7 m / min. As was done in other experiments, when different draw ratios were applied, the draw speed in the furnace was kept almost constant by changing the path length of the sample in the furnace and the speed of the second roll. The furnace was equipped with a number of rolls so that the sample path length in the furnace could be varied from 2.8 to 58.8 meters.

  The appearance of the product changed from the initial opaque white color to almost translucent. The surface was clearly less smooth and glossy than the appearance of the starting product, but was still smooth. In addition, the product felt an increase in roughness and stiffness, and retained the angle after bending.

  The other test results are summarized in Table 1. Note that the resulting nodule strength efficiency is significantly lower than that reported for similar products in EP0740002 B1. This may be related to the type of knot used.

(Comparative Experiment B)
This experiment was performed almost similar to Comparative Experiment A. However, the twisted structure is composed of six strands of the same multifilament yarn, and is given a clockwise twist of 120 revolutions / cm (denoted 6/224; 120Z). The measured paraffin content was about 12% by mass, and the draw ratio was 1.8. The other test results are summarized in Table 2.

Example 1
A 12 pick / cm assembled structure (shown as 8 × Nm44 / 12 in Table 1) containing 8 strands of the SSSY material was used as a precursor. The braid was passed through a furnace as in Comparative Experiment A, but the pretreatment step was not performed and the draw ratio was 1.0. The resulting product looked similar to its starting material. This product was found to have a lower tensile strength than the spun yarn originally used as the strand. The product showed high strength retention after making knots.

(Examples 2-3)
Example 1 was repeated, but here about 12% by weight of paraffin was added before step a) and stretch ratios of 1.8 and 1.7 were applied, respectively. A more translucent appearance of the product indicates that more melting has occurred. The surface feel was less smooth than in Comparative Experiment A. Each of the obtained products has a higher tensile strength than the spun yarn used as a strand, has increased bending resistance (increased rigidity), and maintains the angle after bending. It was found that the number of cycles until the rupture during the wear test was more than five times greater in Example 2 than in Comparative Experiment A.

(Examples 4 to 6)
The assembled structure made of the SSSY material including 8 strands at 9.5 picks / cm was used as a precursor. Although the inside of the furnace was passed similarly to the comparative experiment A, a draw ratio of 1.0 was applied to the braid without a pretreatment step. The resulting product appeared to have a lower tensile strength than the spun yarn used as the strand, but knots could be made with a high strength retention (Example 4). When a draw ratio of 1.6 or 1.7 was applied, the tensile strength increased again as in Examples 2-3. However, the wear resistance was only slightly improved. Clearly, at the temperature and time conditions used, the extent of fiber dissolution was not high enough to obtain high wear resistance without pretreatment.

(Examples 7 to 9)
Examples 4-6 were repeated except that about 13% by weight paraffin was added to the precursor. An increase in strength relative to the original spun yarn was observed for all samples. Example 7 confirms that increasing the degree of melting has a positive effect on wear resistance.

(Examples 10 to 16)
An assembled structure made of the SSSY material including 8 strands at 7.5 picks / cm was used as a precursor. From Example 10, it was confirmed that no increase in tensile strength was observed at a draw ratio of 1.0, and that no melting occurred under no conditions and under the selected conditions. Judging from the change in appearance, the degree of melting increases by increasing the exposure temperature by adding paraffin. The improvement in melting was also evident from the product's decay resistance test by rubbing the product on a metal rod. Example 11 withstood 18 times and Examples 12 and 13 withstood about 33 times. An improvement of 4 to 5 times was observed in the number of cycles until breakage in the wear resistance test. Even higher temperatures or stretch ratios did not provide further improvements in tensile properties with this precursor structure.

(Example 17)
A single strand spun yarn SSSY was used as a precursor. In the pretreatment, an aqueous polyurethane dispersion L9010 (manufactured by GOVI (BE)) was applied by immersion. The polyurethane content was measured to be about 15% by weight (for the resulting product). The combination of pretreatment, heat exposure and stretching at a draw ratio of 1.6 significantly increased the tensile strength of the product. This product was also more rigid and had a more translucent appearance, and knots could easily be made with high strength retention.

(Examples 18 to 22)
As a precursor, six strands (6 / Nm44; indicated as 120Z) based on SSSY having a clockwise twist of 120 revolutions / cm were used. In Example 19, about 13.5 mass% paraffin was added as a pretreatment in combination with a draw ratio of 1.8. This melted product exhibited very good fracture resistance during the wear test, an increase of about 15 times that of Comparative Experiment B. Samples prepared by pretreatment with polyurethane (Examples 20 to 22; PUR content of about 16% by weight) showed very good tensile properties and knot strength (efficiency) and improved wear resistance. .

(Examples 23 to 24)
These products were based on 18 strands (starting strand was SSSY) and had about 12.5% by weight paraffin and were made under the same conditions as above. The results obtained with these thicker products with titers of about 4100 and 2500 dTex, respectively, were comparable to the other results.

Claims (10)

A process for producing a monofilament product from a precursor comprising at least one strand of polyolefin fibers comprising:
a) exposing the precursor to a temperature within the melting point range of the polyolefin for a time sufficient to at least partially melt adjacent fibers;
b) At the same time, the precursor, and a step of stretching at least 1.0 draw ratio, said strands, Ri spun yarn der made of polyolefin staple fibers, said polyolefin is ultra high molecular weight polyethylene Feature method.   The method according to claim 1, wherein the draw ratio is 1.2 to 25. The method according to claim 1 or 2 , wherein the staple fiber is obtained by chopping polyolefin multifilament yarn. It said precursor comprises a twisted strand, the method according to any one of claims 1-3. 5. The method according to any one of claims 1 to 4 , further comprising pre-treating the precursor to promote adhesion between fibers prior to step a). 6. The method of claim 5 , wherein the pretreating step comprises applying oil to the precursor. 6. The method of claim 5 , wherein the pretreating step comprises applying a polyurethane composition to the precursor. Step a) and b) applying a coating composition to the product after further comprising the steps, the method according to any one of claims 1-7. A monofilament-like product comprising at least partially melted spun yarns made of polyolefin staple fibers, obtainable by the method of any one of claims 1-8 . Use of a monofilament-like product according to claim 9 to obtain various semi-finished and finished products, such as fishing lines or cut-resistant articles.