KR101161690B1 - Process for making a 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

Process for producing monofilament-like products {PROCESS FOR MAKING A MONOFILAMENT-LIKE PRODUCT}

The present invention relates to a method for preparing a polymer comprising: a) exposing a precursor containing at least one strand of polyolefin fibers to a temperature within the melting range of the polyolefin for a time sufficient to at least partially fuse adjacent fibers, and b) simultaneously exposing the precursor. A method of making a monofilament-like product from said precursor, comprising stretching at a draw ratio of at least 1.0. The present invention relates to monofilament-like products obtainable by the process, and to the use of such monofilament-like products for the preparation of various semi-finished products and end use products.

Such a method is known from EP 0740002 B1. This patent document describes the melting point range of the polyolefin, while drawing braided, twisted, or stranded and plied fishing lines made from yarns of gel-spun polyolefin filament at a draw ratio of 1.01 to 2.5. A method of making a fishing line from a yarn of filamentous material is disclosed that exposes a filament adjacent to a temperature in the cell for a time sufficient to at least partially fuse. Yarns applied in this process are continuous multi-filament yarns, more particularly those yarns made by so-called gel spinning of very high molar mass polyethylene (UHMwPE), for example the trade name Spectra® or Dyneema. Yarn available under the trade name Dyneema.

Fishing lines are monofilaments made from synthetic polymers, which usually have a round, rigid structure that is convenient to handle during bait throwing, spin and fly fishing. These monofilament fishing lines typically have a stiff nature and a smooth surface, which combine to allow for better drag from the rod reel, which reduces drag and throws further while throwing. Hooked-up fishing lines are less suitable for fishing lines because they tend to loosen at one end of the fishing line, attract water, provide an outer surface that is hooked and entangled, and have an opaque white that looks too good under water. By the method known from EP 0740002 B1, monofilament-like fishing lines can be produced from plaited or braided lines made from polyolefin multi-filament yarns, which do not have the above disadvantages of plaited fishing lines.

A disadvantage of the process described in EP 0740002 B1 is that the resistance to fracture is limited when the product obtained thereby is exposed to wear conditions.

It is therefore an object of the present invention to provide a process for producing monofilament-like products which does not exhibit these disadvantages.

This object is achieved by a) exposing a precursor containing at least one strand (which is a spun yarn made from polyolefin staple fibers) to polyolefin fibers for a time sufficient to at least partially fuse adjacent fibers to a temperature within the melting range of the polyolefin. And b) simultaneously drawing said precursor at a draw ratio of at least 1.0. A method of making a monofilament-like product from said precursor is achieved according to the invention.

In the process according to the invention, the monofilament-like products can be prepared, for example, from twisted or woven polyolefin yarn structures, expressed in the number of cycles until breakage measured in the tests described under the heading "Materials and methods" described below. Abrasion resistance is improved.

The monofilament-like products obtained by the process according to the invention also exhibit a surprisingly high tensile strength than the initial spun yarn or twisted yarns made from the spun yarn and used as precursors. The resulting monofilament-like product further has a pleasant feel or feel and can be easily manipulated and knotted; It also exhibits surprisingly high knot strength and knot strength efficiency. Another advantage of the process according to the invention is that the degree of fusion can be easily changed and controlled, so that a product with a tailored characteristic profile can be obtained. Another advantage is that the monofilament-like products obtained can be effectively coated with the coating composition in further processing steps.

In the process according to the invention, monofilament-like products are prepared from precursors containing one or more strands of polyolefin fibers. A monofilament-like product is a product made from one or more strands containing a plurality of fibers having a look and feel more like a monofilament than a multi-filament yarn or string but typically having a diameter typically less than about 50 μm. I understand. Monofilament-like products can have diameters that vary in a wide range, for example about 0.1-10 mm. As used herein, a precursor is understood to be an article of unlimited length, containing one or more strands of polyolefin fibers and used as feed or starting material. Suitable precursors may be, for example, in the form of a woven string comprising a plurality of strands, braided and wound yarns, strings or ropes, and single-stranded yarns. Polyolefin fiber strands are mainly understood as fibrous products, such as yarns containing at least 50% by mass of polyolefin fibers.

The method according to the invention comprises exposing the precursor to a temperature within the melting point range of the polyolefin for a time sufficient to at least partially fuse adjacent fibers. The conditions of this fusion step are chosen such that the exposure temperature and time are sufficient to soften the polyolefin fibers and at least partially fuse within the specific structure applied. The melting point range of the polyolefin is the temperature range between the peak melting point of the non-oriented polyolefin determined by DSC analysis using a scan-rate of 20 ° C./min and the peak melting point of the defined highly oriented polyolefin fiber. For UHMwPE fibers, which typically exhibit a melting point range of 138 to 162 ° C., the temperature is preferably about 150 to about 157 ° C. The residence time at which the precursor is exposed to the fusion temperature can vary widely, but is typically about 5 to about 1500 seconds. Although higher temperatures tend to improve the fusion process, care should be taken to avoid applying excessively high temperatures, for example, which can cause loss of strength of the product due to partial melting or other molecular relaxation effects. .

During the fusion process, the appearance of the precursor changes from the initial opaque white to the translucent, milky or even substantially transparent surface appearance of the product, depending on the degree of fusion and the type of precursor. As the degree of fusion between the fibers increases, the light transmittance of the product increases. This increase in transparency or light transmission is clearly advantageous for use as fishing line used in water.

For monofilament-like products with low end unwinding, the outer layer of fiber only needs to be at least partially fused as shown by the increase in light transmittance. However, higher degrees of fusion, such as the binding of fibers in the interior of the precursor or strand, are preferred for producing products with higher wear resistance and higher bending stiffness, which is more monofilament-like. The degree of fusion can be adjusted by varying the exposure temperature and / or exposure time in the method according to the invention.

The degree of fusion in the obtained product can be determined, for example, by visual assessment or visually using an optical or electron microscope, or by measuring mechanical properties such as strength or stiffness. Another possibility is to determine the absorption and absorption rate of the colored liquid, for example from the marker, as described in EP 0740002 B1. The degree of fusion may also be derived from tests in which the loaded product is worn over a metal rod and the number of shifts in which the monofilament-like product decomposes into the filaments that make up it.

In a particular embodiment of the method, the degree of fusion is very low or even hardly measurable on the obtained product. Surprisingly, it has been found that these products drawn at elevated temperatures show significantly improved tensile strengths compared to their precursors and only slightly better wear resistance. Accordingly, the present invention also relates to a process for drawing a woven or twisted structure containing at least one strand of yarn made from polyolefin staple fibers at a draw ratio of at least 1.1 while exposing it to a temperature within the melting range of the polyolefin. The product obtained in this way shows improved tensile properties but still has bending properties more similar to the starting structure.

The method according to the invention also comprises co-drawing the precursor to a draw ratio of at least 1.0, also referred to as draw ratio. Applying one or more draw ratios to the precursor during exposure to heat prevents a decrease in the strength of the product. A draw ratio of 1.1 or higher tends to improve tensile strength in particular. Surprisingly, the strength of the product was found to be significantly higher than the precursor or strand contained within the precursor. Exceeding a certain draw ratio may eliminate this effect or even reduce the strength due to partial damage or destruction of the fiber. Also, the higher the draw ratio, the lower the titer of the resulting product. Thus, the maximum draw ratio depends on the type of precursor and its fibers, and is usually about 50 or less. Preferably, the draw ratio is 1.1 to 40, 1.2 to 25, more preferably 1.3 to 10, even 1.4 to 5.

Preferably, the product obtained after step b) is cooled while maintaining under tension. This better retains the orientation at the fiber level and at the molecular level of the product obtained during fusion and stretching. This tension is for example caused by winding the product into the package following the preceding steps of the process.

In the process according to the invention, at least one strand of the precursor is a spun yarn made from polyolefin staple fibers, ie spun yarn comprising at least 50 mass% polyolefin staple fibers. Generally, the yarn can be made from continuous filaments, staple fibers or a combination thereof. Natural fibers can be classified into two categories: short staple fibers (such as cotton having a typical staple or filament length of 15 to 60 mm) and long staple fibers (such as wool having a typical staple length of 40 to 200 mm). First, synthetic fibers are prepared as continuous filaments; These can be converted into staple fibers by a cutting or stretching breaking process. Cutting typically has a uniform filament distribution (all filaments have approximately the same length), but a slight change in the filament length distribution is possible with the strain system. Stretch failure usually produces staple fibers with a more Gaussian distribution of filament lengths. In the stretch breaking process, the filaments are stretched between several sets of rollers operated at different speeds until the filaments break.

Staple fibers can be fabricated into yarns by a process of pulling and winding parallel fiber strands, commonly referred to as spinning. For this reason, yarns made from staple fibers are called spun yarns.

The industrial yarn spinning process includes the following basic process steps: loosening, carding, drawing and spinning. Mitigation refers to, for example, separating and optionally cleaning the package staple fibers. Carding is to further relax and separate the fibers, for example by passing the fibers between the needle-covered rotating drums. This results in a thin web of partially parallel fibers, which forms rope-like strands, often called slivers. Combing can then improve the orientation of the fibers and remove small fibers. During drawing, the sliver is drawn in one or more steps. In order to obtain a uniform fiber density, several slivers of the same or different staple fibers can be blended together. Mixing the staple fibers in the carding step can also produce yarns comprising blends of different natural and / or synthetic fibers. Before feeding to the spinner, the sliver can be additionally drawn while curling slightly (called roving). During spinning, the sliver or roving is further drawn, more wrapped to stick the overlapping fibers, and the yarn wound into the bobbin. Such a package of wound yarn may be conical or cylindrical, commonly referred to simply as a package.

The spinning process described produces a single stranded yarn (also called a single yarn) that is wound. Depending on the winding direction applied, these yarns are often referred to as S or Z yarns. Wrapped single-stranded yarns are usually quite 'lively'. This means that the yarn itself tends to be entangled, entangled, bent or curled when held under insufficient tension. In order to reduce this pharmacokinetics, ie to obtain a mild or balanced yarn that can be processed further satisfactorily into a fabric, for example, it is usually necessary in the industry to combine two or more strands of a single yarn in an additional step. Has been tolerated. This joining step is commonly referred to as nesting or twining. For example, two folded or two-piled yarns may be wound by winding two single-strand Z yarns together with an S-wound, or by stitching Z and S yarns together. It can manufacture. The nested yarns thus obtained may also be stronger and more uniform than single-stranded yarns.

The spun yarns applied in the process according to the invention comprise at least 50 mass% polyolefin staple fibers. The spun yarn may further comprise up to 50% by mass of one or more other staple fibers, such as natural or synthetic fibers, to make blend yarns. Suitable examples of such second staple fibers include wool, polyolefins, acrylics, polyesters or polyamides (including aromatic polyamide fibers).

In a particular embodiment of the process according to the invention, the spun yarn comprises a predetermined amount of staple yarns made from thermoplastic polymers having a lower melting point range than polyolefin staple fibers. The advantage is that additional thermal bonding can occur during step a). The use of spun yarns in the process according to the invention enables this possibility, since making blended spun yarns is easier and more economical than producing blended multi-filament yarns. Examples of suitable thermoplastic polymers include copolymers of one or more alpha-olefins with other monomers such as LLDPE, or ethylene-acrylic copolymers. The effective amount of such staple fibers can be determined experimentally and is usually about 5-25 mass%.

In another particular embodiment according to the present invention, the main component of the spun yarn is not a polyolefin staple fiber, but a staple fiber made from a high strength, high modulus filament yarn with higher heat resistance than polyolefin and which cannot be thermally bonded by itself ( Examples are aromatic polyamide yarns, such as Kevlar® or Twaron®, liquid crystalline polyester yarns or polybenzoxazoles or polybenzothiazole-based yarns). These spun yarns further comprise up to 50% by mass of staple yarns made from thermoplastic polymers having a relatively low melting point range, for example polyolefin staple fibers having melting points below 200 ° C. Examples of suitable thermoplastic polymers include copolymers of one or more alpha-olefins with other monomers such as LLDPE or ethylene-acrylic copolymers. The advantage of this embodiment is that thermal bonding may occur during step a), while in the absence of low melting fibers, by exposing to heat while stretching high rigid, high modulus filament yarns having high heat resistance Cannot produce monofilament-like products from these yarns. An effective amount of such thermoplastic heat-compatible staple fibers can be determined experimentally and is usually about 5 to about 25 mass%. Monofilament-like products based on spinning yarns comprising aromatic polyamide staple fibers and heat-compatible staple fibers, prepared by the method, combine high strength, high wear resistance and high heat resistance.

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

The choice of other staple fibers (e.g., type, length, potency (dpf), whether they can be fused with the polyolefin staple fibers under applied temperature and time conditions) and / or the choice of additives is largely due to the ultimate properties desired. Determined, and can be made by those skilled in the art using general knowledge or routine testing.

Preferably, the spun yarns applied in the process according to the invention comprise at least 60, 70, 80 or even at least 90% by mass of polyolefin staple fibers, since they can make the mechanical properties of the product obtained better. . For this reason, the yarns to be applied most preferably essentially comprise only the staple fibers.

Staple fibers obtained from various polyolefin yarns can be selected as staple fibers for application to the process according to the invention. Particularly suitable polyolefin yarns are prepared from homopolymers and copolymers of ethylene or propylene. In addition, the polyolefins used may contain small amounts of one or more other monomers, in particular other alpha-olefins. Good results are achieved when linear polyethylene (PE) is selected as the polyolefin. Linear polyethylene is understood here as polyethylene having less than 1 side chain per 100 carbon atoms, preferably polyethylene having less than 1 side chain per 300 carbon atoms; Branches or branches usually contain 10 or more carbon atoms. The linear polyethylene may further contain up to 5 mole percent of one or more comonomers, such as alkenes (eg propylene, butene, pentene, 4-methylpentene or octene). In addition to polyolefins, the fibers may contain small amounts of solvents or additives customary in such fibers, such as antioxidants, spin-finishing agents, heat stabilizers, colorants, and the like.

Preferably, the polyolefin fibers, in particular polyethylene fibers, have an intrinsic viscosity (IV) higher than 5 dl / g. Because of their long molecular chains, these polyolefin fibers with IV have very good mechanical properties such as high tensile strength, modulus and energy absorption upon breakdown. This is also why even more preferred polyolefins are polyethylene with IVs greater than 10 dl / g. Determine the IV according to method PTC-179 (Hercules Inc., April 29, 1982) (dissolution time 16 hours) in decalin and the antioxidant is 2 g of DBPC per liter of solution Viscosities at different concentrations are assumed to be zero concentrations. Polyethylenes having such a high viscosity are often called UHMwPE. Spinning a solution of UHMwPE into gel fibers and drawing the fibers before, during and / or after partial or complete removal of the solvent (ie EP 0205960 A, WO 01/73173 A1, Advanced fiber spinning technology; UHMwPE filament yarns can be prepared by Nakajima Edit, Woodhead Publ. Ltd (1994), ISBN 185573 182 7 and the so-called gel-spinning method described in the references cited therein).

Preferably, UHMwPE staple fibers are chosen because they combine high strength with low relative density. More specifically, the spun yarns applied in the process according to the invention comprise UHMwPE staple fibers made from a multi-filament UHMwPE yarn via a draw-break process, which is a better mechanical due to the wider fiber length distribution of such staples. This is because a yarn having characteristics is obtained.

In a particular embodiment, the spun yarn applied is a single-stranded spun yarn. In another embodiment, the single-stranded spinning yarns described in co-pending applications not yet published are applied to the method according to the invention. This single stranded yarn has a tensile strength of at least 16 cN / dtex; Tensile modulus of 700 cN / dtex or more; And at least 50 mass% of staple fibers obtained from continuous polyolefin multifilament yarns having denier / fiber filaments of 18 dpf or less; The staple fibers have an average fiber length of 40 to 180 mm and essentially do not show crimps; The yarns have a level of weave characterized by an α winding coefficient of 40 to 100 t · m ⁻¹ . (M / g) ^−1/2 . Preferably, staple fibers are obtained from highly-oriented polyolefin fibers such as those based on very high molar mass polyethylene (UHMwPE). The advantage of this process is that translucent monofilament-like products having relatively low titers and low relative densities of, for example, 10 to 100, preferably 15 to 50 dTex, are known from EP 0740002 A1 starting from multi-filament yarns. Compared to higher overall production rates and lower total costs. The products obtained by this method are particularly suitable for medical applications such as surgical sutures.

The α winding coefficient describes the yarn's winding level according to the Koechlin equation below:

T = α (Nm) ^1/2

Where

T is the winding level expressed in turns per meter (tm ^-1 ),

Nm is the metric yarn count (1000 / tex or m / g).

This winding coefficient is also referred to as a (metric) winding factor or winding multiplier. See, eg, http://www.fibre2fashion.com/GLOSSARY/glossary17.htm. Preferably, the winding coefficient is 60 to 100, 65 to 90, or even 70 to 85.

Single-stranded spun yarns exhibit little pharmacokinetics and are mild enough to be able to be further processed without first producing a nested yarn. Staple fibers of single-stranded yarn are obtained from filament yarns having a linear density of 18 denier / filament (dpf), preferably 14 dpf or less, more preferably 10 dpf or less, even more preferably 6 dpf or less, or 4 dpf or less. It became. The lower the linear density of the fibers, the thinner the yarns can be, because a certain minimum number of fibers are needed in the cross section to provide a yarn of sufficient integrity. In addition, due to the lower linear density of the fibers, higher tensile strength of the spun yarn is obtained at a constant yarn titer. In terms of fiber production efficiency, the linear density is preferably 0.2 dpf or more, 0.3 dpf or more, or 0.5 dpf or more. Starting from thinner spinning yarns has the advantage that thinner monofilament-like products can be produced in a more economical manner.

The single-stranded yarns applied in the process according to the invention comprise polyolefin staple fibers which are essentially non-wrinkle, which fibers are not woven or only slightly woven. Wrinkles are a measure of the waviness of a fiber and can be expressed as the difference between the length of the straightened or fully straightened fiber and the wrinkled length (ie, the length of the fiber when there is substantially no external restraint). Essentially not wrinkled is understood herein to mean that the length of the staple fibers in the unsuppressed state is at least 80% of the straight length. Preferably, the corrugated length is at least 90%, even at least 95% of the straight length. Essentially free of wrinkles is also understood to not include permanent wrinkles. For example, UHMwPE staple fibers may exhibit some wrinkles that may be introduced during staple preparation, but these wrinkles are not permanent, which is essentially absent when exposing the fibers to stretching forces that may occur during spinning, for example. For it will lose.

In the process according to the invention, at least one of the precursors is a spun yarn made from polyolefin staple fibers. The precursor also contains one or more strands made from other staple fibers and / or continuous filaments to produce monofilament-like products of different degrees of fusion between and within the strands, and with different mechanical properties, appearance and feel Indicates. One skilled in the art can make these changes using conventional knowledge or routine experimentation. Preferably, all the strands of the precursor are spun yarns based on polyolefin staple fibers, since this can change the degree of fusion and thus product properties to a large extent.

Precursors of various structures, such as intertwined structures or twisted and wound structures, can be used to carry out the process according to the invention. Preferably a precursor having strands that are twisted (or nested) and wound are applied. This has the advantage that precursors can be produced more easily and more cost-effectively and the resulting product exhibits better performance, in particular surprisingly good fracture resistance during abrasion testing.

The method according to the invention may further comprise the step of pretreatment of the precursor or one or more strands therein prior to step a) to enhance interfiber bonding during the fusing step. This pretreatment step may coat a precursor having a particular component or composition; Rubbing off precursors (ie, washing off surface components such as rotary finishes, etc.); Applying a high-voltage plasma or corona treatment.

In one embodiment, non-volatile for mineral oils (e.g., heat transfer grade mineral oils having an average molar mass of about 250 to 700), for example by dipping or wetting, vegetable oils (e.g. coconut oil), or preferably non-volatile for polyolefins. Pretreat the precursor by adding a solvent (eg paraffin). This pretreatment step can be carried out at ambient conditions or at elevated temperatures below the melting point range of the polyolefin fibers.

In another embodiment, the pretreatment comprises applying a coating composition to the precursor, wherein the composition is a solution of a polymer that enhances fiber or fiber bonds or otherwise improves performance during exposure to higher temperatures in the fusing step or It may be a dispersion. In a preferred embodiment, the precursor is coated with a polyurethane composition, such as a dispersion of film-forming polyurethane. Such compositions may further comprise components that contribute to improving the wear and cut resistance of the monofilament-like product. Examples of components that improve cut resistance are small fine particles of high surface hardness such as mineral particles, ceramic particles, glass, metals and the like. The coating composition may further comprise other additives such as colorants or stabilizers.

The method according to the invention may further comprise the step of adding a coating composition to the product after steps a) and b) to form a coating layer. Such coating compositions include typical rotary finishes that allow for easier handling and processing of the product in subsequent operations; Compounds or compositions that modulate adhesion during subsequent preparation of a composite article comprising the present product; Or a binder composition that further enhances the integrity and strength of the product. Typical examples of the latter include polyurethane or polyolefin-based (eg ethylene-acrylic copolymer) binder compositions. The coating composition can be applied as a solution or dispersion. Such compositions may further comprise components that further improve the wear or cut resistance of the monofilament-like product. Examples of components that improve cut resistance are small particles of high surface hardness (eg, various minerals or ceramic particles). The coating composition may further include other additives such as colorants, stabilizers, and the like.

Application of the coating composition in the process according to the invention has been found to be relatively easy and effective compared to the method of adding continuous filament yarn as a precursor. Clearly, the product obtained after steps a) and b) is more acceptable for such coatings, especially when the fibers on the product surface are only partially fused.

The invention also relates to a monofilament-like product comprising at least partially fused spun yarn made from polyolefin staple fibers and obtainable by the process according to the invention. This product has a unique structure and combines some advantageous properties; It has the translucent appearance of the monofilament but its texture and feel is different from the polyolefin monofilament or monofilament-like products known, for example, from EP 0740002 B1. Monofilament-like products according to the invention exhibit surprisingly high fracture resistance during abrasion testing; It can be easily knotted and the knotted product exhibits high strength retention. Monofilament-like products also exhibit surprisingly high tensile strengths, which are significantly higher than the strength of the starting yarn in the precursor. Typically, the monofilament-like product has a tensile strength of at least 10 cN / dtex, preferably at least 15, 20 or even 25 cN / dTex. Such high strengths are typically observed in precursor based products comprising a relatively large amount of spun yarn based on UHMwPE staple fibers.

Monofilament-like products obtainable by the process according to the invention have a linear density (also called titer) which can vary within wide limits, such as 10 to 15000 dTex. In general, the product has a titer of 30 to 2500 dtex. Lower titer products are suitable for use as sutures and the like. In light of uses such as fishing lines, or protective garments and clothing, the titer is preferably between 100 and 1600 dTex, even more preferably between 200 and 1200 dTex.

The invention also relates to the use of the monofilament-like product according to the invention for the production of various semi-finished products and end-use products such as fishing lines; sutures, textiles; laces and ropes; composite yarns, and for example cutting To their use in sex products.

The invention also relates to semi-finished products and end-use products comprising the monofilament-like products according to the invention.

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

Materials and methods

Dynema® Multi-Filament UHMwPE Yarn 1760SK60 (DSM High Performance Fibers) with a titer of 1760 dTex, tensile strength of 28 cN / dTex, tensile modulus of 910 cN / dTex, and denier / fiber filaments of about 1 dpf Fibers), The Netherlands) were made into staple fibers, for example by the draw-break process described in EP 0445872 A1. The average length of the staple fibers was about 80 mm. The staple fibers were then spun into single-stranded yarns using NSC equipment of the long staple fiber type. The yarn obtained had a yarn count of about Nm 44 (about 225 dTex), and the level of entrainment applied corresponded to the Sheave Law coefficient of about 80. As the yarn was fixed vertically at only one end and cut to a length of 100 cm, almost no tendency to wind around was observed, and the yarn was almost non-vibrating. Its 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 on multiple filament yarns and spun yarns, and monofilament-like products as defined in ASTM D885M using a nominal gauge fiber length of 500 mm, a crosshead speed of 50% / min, and an Instron 2714 clamp. Or strength) (and tensile modulus). To calculate the strength, the measured tension is divided by the titer determined by weighing 10 m (or other length) of the fiber. Elongation is the measured elongation at break, expressed in% of original length after clamping the specimen.

Knot strength is determined by measuring the strength of a specimen comprising Palomar-knot. Paloma-knots are a versatile connection that is recommended for connecting fishing lines to spinning hooks, snaps or hooks. Passing both ends of the specimen through the holes in the hook creates a simple overhand knot. Then, the hook was passed through the loop and the knot was firmly tightened.

Knot strength efficiency is calculated as the relative value (%) of measured knot strength to measured tensile strength.

Wear resistance was measured according to a procedure based on the test described by ASTM D3108 to determine yarn friction. For this purpose, the yarn friction measuring apparatus described in ASTM D3108 was deformed in such a way that one end of the sample to be tested was fixed to an eccentric crank or cam rotated by a motor, and the other end was suspended. During the test, the sample is polished against the ceramic center and the number of cycles until the sample breaks (breaks) is determined. The given number is the average of five or more tests.

Comparative Experiment A

As a precursor (feed), a plaited structure made from a multi-filament gel-spun UHMwPE yarn having a titer of 224 dTex, a tensile strength of 39 cN / dTex, a tensile modulus of 1250 cN / dTex, and a denier / fiber filament of about 1 dpf It was. This cord contained 8 strands of the yarn interwoven with medium firmness expressed as a pick per centimeter of 7.5 (indicated by 8 × 224 / 7.5; see Table 1).

The cord was passed through a liquid paraffin bath as a pretreatment step and the excess oil was wiped off by passing between the nonwovens. By determining the mass increase at this stage, the paraffin content was calculated to be about 11 mass%. This braid was then guided onto the first drive roll at a constant rate of 10 m / min and placed into an oven maintained at a constant temperature of 153.5 ° C. At the oven outlet, the braid was led onto the second drive roll. The speed of the second roll was adjusted so that a draw ratio of 1.9 and an elongation of 0.7 m / min were applied. If different draw ratios are to be applied as in some other experiments, the elongation in the oven is kept approximately constant by varying the path length of the sample in the oven and the speed of the second roll. Multiple rolls may be installed in the oven such that the sample path length in the oven is between 2.8 and 58.8 m.

The product appearance changed from almost opaque white to almost translucent; His surface was clearly less smooth and less shiny than the starting product, but still quite smooth. In addition, the product felt rougher and stiffer and maintained angle after bending.

The results of additional tests are collected in Table 1. The knot strength efficiency observed is significantly lower than that reported for similar products of EP 0740002 B1; This may be related to the type of knot used.

Comparative Experiment B

The experiment was performed very similarly to Comparative Experiment A, except that 120 turns / cm of clockwise winding was applied to produce a twisted and twisted structure (6/224; denoted by 120Z) from the same multifilament yarn 6 strands. . The measured paraffin content is about 12% by mass; The drawing ratio was 1.8. Additional test results are collected in Table 1.

Example 1

A plaited structure containing 8 strands of the SSSY material described above having 12 picks / cm (denoted as 8 × Nm 44/12 in Table 1) was used as precursor. Similar to Comparative Experiment A, the cord was passed through an oven, but without a pretreatment step and a draw ratio of 1.0 was applied. The resulting product had a similar appearance to its starting material and was found to have a lower tensile strength than the spun yarn initially applied as a strand. This product showed high strength retention after the knot was made.

Examples 2 and 3

About 12% by mass of paraffin was added before step a) and Example 1 was repeated with a draw ratio of 1.8 and 1.7 respectively. The more translucent appearance of the product indicates that more fusion has taken place. The surface feel was less smooth than that of Comparative Experiment A. Both resulting products have higher tensile strength than the spun yarns applied as strands, have higher bending resistance (stiffer), and maintain their angle after bending. The number of cycles to failure during the abrasion test was found to be at least five times greater than Comparative Experiment A for Example 2.

Examples 4-6

A laced structure made from the SSSY material described above containing 8 strands with 9.5 picks / cm was used as precursor. Similar to Comparative Experiment A, this cord was passed through an oven, but without a pretreatment step and a draw ratio of 1.0 was applied. The resulting product was found to have lower tensile strength than the spun yarns applied as strands; Knots with high strength retention could be made (Example 4). If a draw ratio of 1.6 or 1.7 is applied, the tensile strength increases again as in Examples 2 and 3; Wear resistance was only slightly better. Clearly, under the temperature and time conditions applied, the degree of fusing of the fibers was not high enough to exhibit high wear resistance without pretreatment.

Examples 7-9

Examples 4-6 were repeated adding about 13% by mass of paraffin to the precursor. An increase in strength was observed in all samples compared to the original yarn; Example 7 demonstrates the positive effect on wear resistance of higher degrees of fusion.

Examples 10 to 16

A plaited structure made from the SSSY material described above containing 8 strands with 7.5 picks / cm was used as precursor. Example 10 demonstrated no increase in tensile strength at a draw ratio of 1.0 and little fusion occurred under selected conditions without pretreatment. Adding paraffin and increasing the exposure time increases the degree of fusing as judged from the change in appearance. Improvement of fusion was also evident by testing the product's degradation resistance when the product was rubbed on a metal rod; Example 11 was able to withstand 18 movements, while Examples 12 and 13 were able to withstand about 33 movements. In the abrasion resistance test, a 4 to 5 fold increase in cycle number until fracture was observed. In the case of this precursor structure, the tensile properties were not further improved by higher temperatures or draw ratios.

Example 17

Single strand strand yarn SSSY was used as precursor. Pretreatment consisted of adding L9010 from GOVI (Belgium), an aqueous polyurethane dispersion via dipping. The polyurethane content was determined to be about 15% by mass (in the resulting product). The combination of pretreatment, heat exposure and drawing of draw ratio 1.6 significantly increased the tensile strength of the product. The product also had higher stiffness, more translucent appearance, and could easily make knots with high strength retention.

Examples 18-22

As precursor, an SSSY-based 6-ply yarn (denoted as 6 / Nm44; 120Z) with a clockwise twist of 120 turns / cm was added. In Example 19, about 13.5 mass% paraffin was added as a pretreatment, and a draw ratio of 1.8 was combined. This fused product was very resistant to breakage during the abrasion test, increasing about 15 times compared to Comparative Experiment B. Samples pretreated with polyurethane (Examples 20-22; PUR content of about 16% by mass) showed very good tensile properties and knot strength (efficiency) and showed improved wear resistance.

Examples 23 and 24

The product was based on 18 ply wrapped yarns (starting strand was SSSY) with about 12.5% by mass paraffin and were prepared under similar conditions as before. The results obtained for these thicker products with titers of about 4100 and 2500 dTex, respectively, are in harmony with the other results.

Claims (11)

a) exposing a precursor containing at least one strand of polyolefin fiber to a temperature within the melting range of the polyolefin for a time sufficient to at least partially fuse the adjacent fibers, and b) simultaneously expose the precursor to 1.0 Stretching at a draw ratio above, wherein the strands are spun yarns made from polyolefin staple fibers and the polyolefin is a very high molar mass polyethylene having an intrinsic viscosity of greater than 5 dl / g. , A process for preparing monofilament-like products from precursors containing one or more strands of polyolefin fibers. The method of claim 1, The draw ratio is 1.2 to 25. delete The method of claim 1, A process for obtaining staple fibers by stretching-breaking polyolefin multifilament yarns. The method of claim 1, A method in which the precursor is plied and contains strands. The method of claim 1, Further comprising pretreating the precursor prior to step a) to enhance interfiber bonding. The method of claim 6, Wherein the pretreatment comprises applying an oil to the precursor. The method of claim 6, Pretreatment comprises coating the polyurethane composition to the precursor. The method of claim 1, Further comprising applying a coating composition to the article after steps a) and b). A monofilament-like product comprising at least partially fused spun yarn made from very high molar mass polyethylene staple fibers having an intrinsic viscosity higher than 5 dl / g. 11. The method of claim 10, Monofilament-like products used to make a variety of end-use and semi-finished products selected from the group consisting of fishing lines and cut resistant products.