Ultrahigh-molecular-weight polyethylene fusible yarn and method for producing same

Abstract

Provided is an ultrahigh molecular weight polyethylene multifilament and an ultrahigh-molecular-weight polyethylene containing a liquid paraffin having an average molecular weight of 400 or greater. This fusible yarn has a liquid paraffin content that exceeds 0 wt% but is no greater than 13 wt% with respect to the total yarn, and of this liquid paraffin content, the content at the yarn surface exceeds 0 wt% but is no greater than 10 wt%.

Description

Ultra-high molecular weight polyethylene fusible yarn and its manufacturing method

[0001] The present invention relates to a fusion yarn in which a plurality of ultra-high molecular weight polyethylene filaments are fused together, and a method for producing the same.

[0002] Monofilament yarns and multifilament yarns consisting of multiple monofilaments are known as yarns used in aquatic materials such as fishing lines and fishing nets, as well as ropes and racket strings. For example, monofilament yarns have excellent surface smoothness and low frictional resistance. Therefore, when used as fishing line, monofilament yarns allow for the casting of fishing tackle farther. Furthermore, monofilament yarns do not retain water inside, allowing for good drainage. However, because monofilament yarns generally have high rigidity, the thicker they are, the less flexible they become, making them less suitable for use as fishing line. Among these, ultra-high molecular weight polyethylene filaments have high strength, but they are difficult to manufacture in proportion to their thickness, and their increased rigidity makes them difficult to handle.

[0003] On the other hand, by appropriately setting the number and thickness of monofilaments, multifilament yarn can be made into a yarn with a desired thickness and excellent flexibility. Therefore, multifilament yarn is easy to handle and can be suitably used, for example, as fishing line. Ultra-high molecular weight polyethylene multifilament yarn has the advantage of being easy to handle while being high in strength. However, ultra-high molecular weight polyethylene multifilament yarn has the problem of poor drainage because it tends to trap water inside. Furthermore, ultra-high molecular weight polyethylene multifilament yarn has the problem that filaments at cut sections may become loose and fluff. Note that "loosening" refers to the separation of a single bundle into multiple pieces. Multifilament yarns that have a single-thread-like form like a monofilament yarn have good drainage and can also suppress fraying of the filaments. Hereinafter, a single-thread-like form like a monofilament yarn will be referred to as "monofilament-like."

[0004] The present applicant has previously proposed an ultra-high molecular weight polyethylene fusion yarn in which each filament is sufficiently fused, which contains 15% by weight or more of liquid paraffin having an average molecular weight of 400 or more (Patent Document 1).

[0005] Patent No. 6862031

[0006] The ultra-high molecular weight polyethylene fusion yarn is used, for example, as a fishing line, etc. Because the fishing line comes into contact with the guides of a reel or a fishing rod, the ultra-high molecular weight polyethylene fusion yarn is required to have not only excellent fusion properties but also a low coefficient of dynamic friction.

[0007] An object of the present invention is to provide an ultra-high molecular weight polyethylene fusible yarn having excellent fusibility and a low coefficient of dynamic friction.

[0008] In one aspect of the present invention, there is provided an ultra-high molecular weight polyethylene fusion yarn. The ultra-high molecular weight polyethylene fusion yarn in a first example is a fusion yarn comprising an ultra-high molecular weight polyethylene multifilament and liquid paraffin having an average molecular weight of 400 or more, wherein the liquid paraffin content is more than 0 wt % and not more than 13 wt % of the entire yarn, and the liquid paraffin content present on the yarn surface is more than 0 wt % and not more than 10 wt %.

[0009] The second example of the ultra-high molecular weight polyethylene fused yarn is the ultra-high molecular weight polyethylene fused yarn of the first example described above, except that the liquid paraffin content is greater than 0% by weight and not more than 8% by weight relative to the entire yarn, and the liquid paraffin content present on the yarn surface is greater than 0% by weight and not more than 6% by weight.

[0010] The third example of the ultra-high molecular weight polyethylene fused yarn is the ultra-high molecular weight polyethylene fused yarn of the first example described above, except that the liquid paraffin content is greater than 0% by weight and not more than 5% by weight relative to the entire yarn, and the liquid paraffin content present on the yarn surface is greater than 0% by weight and not more than 2% by weight.

[0011] The ultra-high molecular weight polyethylene fusion yarn of the fourth example is the ultra-high molecular weight polyethylene fusion yarn of any one of the first to third examples, wherein the fineness of the fusion yarn is 10 dtex or more and 500 dtex or less.

[0012] In another aspect of the present invention, there is provided a method for producing an ultra-high molecular weight polyethylene fusion yarn. The method for producing an ultra-high molecular weight polyethylene fusion yarn is the method for producing an ultra-high molecular weight polyethylene fusion yarn of any of the first to fourth examples above, and includes the steps of impregnating an ultra-high molecular weight polyethylene multifilament with liquid paraffin having an average molecular weight of 400 or more, obtaining a fusion yarn precursor by heating and drawing the ultra-high molecular weight polyethylene multifilament containing the liquid paraffin, and removing the liquid paraffin present on the surface of the fusion yarn precursor by contacting the fusion yarn precursor with a removing liquid.

[0013] The ultra-high molecular weight polyethylene fusion yarn of the present invention has excellent fusibility and is therefore less likely to separate into individual filaments. Such ultra-high molecular weight polyethylene fusion yarn has a monofilament-like structure and is easy to drain. Furthermore, the ultra-high molecular weight polyethylene fusion yarn of the present invention has a low coefficient of dynamic friction and is therefore suitable for use as, for example, fishing line.

[0014] 8. A front view showing one form of an ultra-high molecular weight polyethylene multifilament. A front view showing another form of an ultra-high molecular weight polyethylene multifilament. A front view showing another form of an ultra-high molecular weight polyethylene multifilament. A reference diagram showing one form of an apparatus for producing ultra-high molecular weight polyethylene fusion yarn. A reference diagram showing the systems of an impregnation device and an excess removal device. A reference diagram showing another form of an apparatus for producing ultra-high molecular weight polyethylene fusion yarn. The same reference diagram. A front view of an ultra-high molecular weight polyethylene fusion yarn. A reference cross-sectional view cut and enlarged along line IX-IX in FIG. 8. An explanatory diagram of a method for evaluating yarn stickiness.

[0015] The present invention will be described below with reference to the accompanying drawings. In this specification, when a plurality of numerical ranges each having a value between a lower limit and an upper limit are separately described, it is understood that any lower limit and any upper limit can be selected to set a numerical range of "any lower limit and any upper limit."

[0016] [Outline of Ultra-High Molecular Weight Polyethylene Fusion Yarn] The ultra-high molecular weight polyethylene fusion yarn of the present invention comprises ultra-high molecular weight polyethylene multifilaments and liquid paraffin, and the ultra-high molecular weight polyethylene multifilaments are fused together. The ultra-high molecular weight polyethylene fusion yarn has a liquid paraffin content of more than 0% by weight and not more than 13% by weight relative to the entire yarn, and the liquid paraffin content on the yarn surface is more than 0% by weight and not more than 10% by weight. The ultra-high molecular weight polyethylene fusion yarn has excellent fusion properties, resulting in a monofilament-like structure, and also has the advantage of a low dynamic friction coefficient. Herein, the term "ultra-high molecular weight polyethylene fusion yarn" refers to a yarn obtained by fusing each ultra-high molecular weight polyethylene monofilament that constitutes an ultra-high molecular weight polyethylene multifilament. The term "ultra-high molecular weight polyethylene multifilament" refers to the state before the individual monofilaments are fused together, and the term "ultra-high molecular weight polyethylene monofilament" refers to the ultra-high molecular weight polyethylene long fiber that constitutes the ultra-high molecular weight polyethylene multifilament. Hereinafter, "ultra-high molecular weight polyethylene" will be referred to as "UHPE."

[0017] [UHPE Multifilament (UHPE Multifilament Before Fusion)] The UHPE multifilament is composed of multiple UHPE monofilaments. UHPE is polyethylene with an increased molecular weight, for example, polyethylene with a molecular weight of 400,000 or more, preferably polyethylene with a molecular weight of 600,000 or more. The UHPE used has a melting point of 140°C or higher. The UHPE monofilament is a filament produced by so-called gel spinning of UHPE. The tensile strength of the UHPE multifilament is 19.6 cN / dtex or more, preferably 24.5 cN / dtex to 49.0 cN / dtex, and more preferably 29.4 cN / dtex to 39.2 cN / dtex. For example, a commercially available product can be used as such a high-strength UHPE multifilament. Examples of commercially available products include "Dyneema" manufactured by DSM, "Spectra" manufactured by Honeywell, and "Izanas" manufactured by Toyobo Co., Ltd. The tensile strength can be measured in accordance with JIS L 1013 (2010)-8.5.

[0018] The fineness of the UHPE monofilament is not particularly limited. If the fineness of the UHPE monofilament is too small, the gaps between adjacent monofilaments in the multifilament will be relatively small, making it difficult for liquid paraffin to uniformly impregnate the interior of the multifilament, which may result in a decrease in fusion properties. From this perspective, the fineness of the UHPE monofilament is, for example, 0.5 dtex or more, preferably 1.0 dtex or more. On the other hand, if the fineness of the UHPE monofilament is too large, the gaps between adjacent monofilaments in the multifilament will be relatively large, which may result in a decrease in the number of joining points (fusion) between filaments per unit volume. From this perspective, the fineness of the UHPE monofilament is, for example, 5.0 dtex or less, preferably 4.0 dtex or less. In this specification, the unit of fineness (thickness) "tex" is the weight (in grams) per 1000 m, and the unit of fineness (thickness) "dtex" is the weight (in grams) per 10000 m. In the present invention, the fineness can be measured in accordance with JIS L 1013 (2010)-8.3.1-b) Method B.

[0019] The UHPE multifilament is composed of a plurality of the UHPE monofilaments. The number of UHPE monofilaments constituting the UHPE multifilament is not particularly limited and is, for example, 5 to 5,000, preferably 10 to 2,500. The fineness of the UHPE multifilament is generally calculated by multiplying the fineness of the UHPE monofilament by the number of UHPE monofilaments. The UHPE multifilament may be in the form of a plurality of UHPE monofilaments simply drawn together, or in the form of a plurality of UHPE monofilaments drawn together and twisted, or in the form of a braided cord made of a plurality of UHPE monofilaments. The twist may be either an S twist (right twist) or a Z twist (left twist). Examples of the braided cord include a form in which a plurality of filaments are alternately braided, or a form in which a plurality of filaments are braided around a core filament. The filaments used in the braided cord may be twisted in advance. FIG. 1 shows a UHPE multifilament 21 made up of a plurality of UHPE monofilaments 3 that have been drawn together, FIG. 2 shows a UHPE multifilament 22 made up of a plurality of drawn UHPE monofilaments 3 that have been S-twisted, and FIG. 3 shows a UHPE multifilament 23 made up of a plurality of drawn UHPE monofilaments 3 that have been Z-twisted.

[0020] When the UHPE multifilament is twisted, its twist coefficient K1 is not particularly limited, but is preferably more than 0 and not more than 5500, more preferably 1000 or more and 5000 or less, and even more preferably 2000 or more and 4500 or less. By using a UHPE multifilament having a twist coefficient K1 within the above range, a UHPE fusion yarn having a knot strength ratio a / b in the range of 0.9 or more and 1.1 or less can be obtained. Note that a UHPE multifilament in the form of simply paralleling a plurality of UHPE monofilaments has a twist coefficient K1 of zero. The twist coefficient K1 of a UHPE multifilament can be calculated using the formula 1: K1 = t × D １／２However, t in the above formula 1 represents the number of twists (turns / m) of the UHPE multifilament, and D in the above formula 1 represents the fineness (tex) of the UHPE multifilament.

[0021] [Liquid Paraffin] Liquid paraffin is a colorless liquid paraffin under standard conditions (23°C, 1 atmospheric pressure, 50% RH). Liquid paraffin is a collection of alkanes mainly having 20 or more carbon atoms. Mineral oil is a general term for a mixture of hydrocarbon compounds and impurities derived from underground resources such as petroleum, natural gas, and coal. Liquid paraffin differs from mineral oil in that it is made by refining alkanes having 20 or more carbon atoms. In the present invention, liquid paraffin having an average molecular weight of 400 or more is used, preferably liquid paraffin having an average molecular weight of 420 or more, more preferably liquid paraffin having an average molecular weight of 430 or more, and even more preferably liquid paraffin having an average molecular weight of 450 or more is used. By incorporating predetermined amounts of such liquid paraffin into the interior and surface of the yarn, a UHPE fusion yarn having excellent fusibility and a low dynamic friction coefficient can be obtained. There is no particular upper limit to the average molecular weight of liquid paraffin, but if it is too high, the fluidity will decrease, and it may be difficult for the liquid paraffin to uniformly impregnate the interior of the multifilament (the gaps between the monofilaments). From this perspective, the upper limit of the average molecular weight of liquid paraffin is 800 or less, preferably 700 or less, more preferably 600 or less, and even more preferably 490 or less. For example, commercially available liquid paraffin can be used. An example of a commercially available liquid paraffin is "Moresco White" manufactured by MORESCO Corporation. Here, the average molecular weight of liquid paraffin can be calculated in normal paraffin terms using a calibration curve obtained by gas chromatography using normal paraffin as a standard substance. A specific method for measuring the average molecular weight of liquid paraffin is as described in the Examples below.

[0022] [Method for producing UHPE fusion yarn] The method for producing a UHPE fusion yarn of the present invention includes, for example, a step of impregnating a UHPE multifilament with liquid paraffin having an average molecular weight of 400 or more (impregnation step), a step of obtaining a fusion yarn precursor by heating and drawing the UHPE multifilament containing the liquid paraffin (fusion step), and a step of removing the liquid paraffin present on the surface of the fusion yarn precursor (removal step). Note that the removal step does not completely remove the liquid paraffin present on the surface of the fusion yarn precursor (reducing the liquid paraffin on the surface to zero), but rather performs incomplete removal. In other words, the removal step is a step of partially removing the liquid paraffin on the surface of the fusion yarn precursor. Here, "fusion yarn precursor" refers to a UHPE fusion yarn in which a relatively large amount of liquid paraffin remains on the surface.

[0023] Fig. 4 is a reference diagram showing an example of a UHPE fusion yarn manufacturing apparatus 8. The manufacturing apparatus 8 has a zone Z1 for obtaining a fusion yarn precursor 5b (a UHPE fusion yarn having a relatively large amount of liquid paraffin remaining on the surface), and a zone Z2 for actively removing the liquid paraffin from the surface of the fusion yarn precursor 5b. The arrows in Fig. 4 indicate the traveling direction of the UHPE multifilaments 5a and the like (similar to Fig. 5).

[0024] <Zone for fusing UHPE multifilaments to produce a fused yarn precursor> The UHPE multifilament 5a, which is the raw yarn, is loaded into the yarn reel-out device 61. As described above, the UHPE multifilament 5a may be twisted, or the UHPE multifilament 5a may be untwisted. Twist may be added to the UHPE multifilament 5a between the yarn reel-out device 61 and the first drawing device 62. The UHPE multifilament 5a drawn from the yarn reel-out device 61 is drawn while being sent from the first drawing device 62 to the second drawing device 66. As the first and second drawing devices 62, 66, for example, drawing devices composed of a plurality of rollers can be used. Between the first drawing device 62 and the second drawing device 66, an impregnation device 63, an excess removal device 64, and a heating device 65 are arranged in this order. The impregnation device 63 impregnates the UHPE multifilament 5a with liquid paraffin. The method of impregnation with liquid paraffin is not particularly limited, and examples thereof include applying liquid paraffin to the UHPE multifilament 5a using a nonwoven fabric, a woven fabric, a brush, a sponge, or the like; passing the UHPE multifilament 5a through a bath containing liquid paraffin (dipping); and spraying liquid paraffin onto the UHPE multifilament 5a using a spray or the like. The excess removal device 64 removes excess liquid paraffin from the UHPE multifilament 5a after impregnation with liquid paraffin. The removal method is not particularly limited, and examples thereof include wiping off the liquid paraffin using a dry nonwoven fabric or woven fabric, or removing the liquid paraffin from the surface of the UHPE multifilament 5a using a roller or the like. The heating device 65 applies heat to the UHPE multifilament 5a after impregnation with liquid paraffin. The heating device 65 is not particularly limited, and examples thereof include an oven.

[0025] FIG. 5 is a reference diagram showing an example of the impregnation device 63 and the excess removal device 64. In the example of FIG. 5, the impregnation device 63 includes a supply unit 631 that supplies liquid paraffin, a storage unit 632 that stores the liquid paraffin supplied from the supply unit 631, and an impregnation unit 633 that impregnates the UHPE multifilament 5a with the liquid paraffin stored in the storage unit 632. Numerous dots are indicated where the liquid paraffin is present. Liquid paraffin is supplied from the supply unit 631 to the storage unit 632 so that the liquid level of the liquid paraffin in the storage unit 632 is maintained at a predetermined height. A cloth-like material that can be impregnated with liquid paraffin is used as the impregnation unit 633. Examples of the cloth-like material include a nonwoven fabric, felt, or a composite material of a nonwoven fabric and felt that can be impregnated with liquid paraffin. One portion (e.g., a lower portion) of the fabric-like body is immersed in liquid paraffin in a reservoir 632, and the opposite portion (e.g., an upper portion) of the fabric-like body is in contact with the UHPE multifilaments 5a. The liquid paraffin in the reservoir 632 flows down the fabric-like body, which is an impregnation portion 633, and comes into contact with and impregnates the UHPE multifilaments 5a. The impregnation portion 633 is configured so that the distance from the liquid level in the reservoir 632 to the UHPE multifilaments 5a, as well as the contact area and contact pressure (contact strength) of the UHPE multifilaments 5a with the fabric-like body, can be appropriately set. By setting the above items of the impregnation portion 633, the amount of liquid paraffin impregnated into the UHPE multifilaments 5a can be adjusted.

[0026] The excess removal device 64 is disposed downstream of the impregnation section 633. A cloth-like material capable of absorbing liquid paraffin is used as the excess removal device 64. Examples of the cloth-like material include nonwoven fabric, felt, and a composite material of nonwoven fabric and felt that are capable of absorbing liquid paraffin. By wrapping such a cloth-like material around the UHPE multifilaments 5a, excess liquid paraffin from the UHPE multifilaments 5a can be removed. The excess removal device 64 is configured so that the contact area and contact pressure (contact strength) of the cloth-like material with the UHPE multifilaments 5a can be appropriately set. By setting the above items of the excess removal device 64, the amount of excess liquid paraffin removed from the UHPE multifilaments 5a can be adjusted.

[0027] The UHPE multifilament 5a drawn out from the yarn reel-out device 61 is impregnated with liquid paraffin having an average molecular weight of 400 or more in an impregnation device 63 and an excess removal device 64, and the excess is removed. The amount of liquid paraffin contained in the final UHPE fused yarn can be controlled by appropriately adjusting the amount of liquid paraffin impregnated into the UHPE multifilament 5a and the amount of liquid paraffin removed. The UHPE multifilament 5a impregnated with liquid paraffin is heated in a heating device 65. The UHPE multifilament 5a is preferably heated so that its temperature is in the range of 140°C to 158°C. After heating, the UHPE multifilament 5a is drawn in the longitudinal direction in a second drawing device 66 to obtain a fused yarn precursor 5b. The UHPE multifilament 5a can be drawn appropriately by setting the peripheral speed of the rollers of the second drawing device 66 faster than the peripheral speed of the rollers of the first drawing device 62. The draw ratio is preferably in the range of 1.5 to 2.5 times in order to maintain or increase the orientation of the molecular chains of UHPE. Although a one-stage heating and drawing apparatus is illustrated in the illustrated example, the number of drawing stages, the number and length of heating apparatuses, etc. can be changed as appropriate.

[0028] <Zone for Removing Liquid Paraffin from the Surface of the Fusion Yarn Precursor to Prepare a UHPE Fusion Yarn> A predetermined amount of liquid paraffin present on the surface of the fusion yarn precursor 5b is removed. Liquid paraffin present on the surface of the fusion yarn precursor 5b can be easily removed, for example, by contacting the fusion yarn precursor 5b with a removal liquid. Representative examples of the removal liquid include organic solvents. The type of organic solvent is not particularly limited as long as it is a solvent that can dissolve liquid paraffin, and examples include alcohols, ketones, ethers, esters, aliphatic and aromatic hydrocarbons, halogenated hydrocarbons, amides, and cellosolves. Specific examples of organic solvents include n-butanol, 2-butanol, cyclohexanol, isopropyl alcohol, t-butyl alcohol, glycerin, ethylene glycol, acetone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 2-pentanone, 2-hexanone, diethyl ether, tetrahydrofuran, dioxane, anisole, ethyl acetate, butyl acetate, methyl lactate, n-hexane, benzene, toluene, xylene, chloroform, dichloromethane, dichloroethane, dimethylformaldehyde, dimethylacetamide, methyl cellosolve, ethyl cellosolve, etc. These solvents can be used alone or in combination of two or more.

[0029] For example, the fusion yarn precursor 5b is passed through a bath 71 containing a removal liquid such as an organic solvent. The removal liquid in the bath 71 in FIG. 4 is marked with numerous large dots. The fusion yarn precursor 5b is transported through the bath while in contact with the removal liquid, thereby removing the liquid paraffin from the surface of the fusion yarn precursor 5b. The amount of liquid paraffin removed from the surface of the fusion yarn precursor 5b can be controlled by adjusting the type of removal liquid and the time the fusion yarn precursor is in contact with the removal liquid. If necessary, the bath 71 may be equipped with a brush or an ultrasonic generator. Tracing the surface of the fusion yarn precursor 5b with a brush or applying ultrasonic waves to the removal liquid in the bath 71 enhances the effectiveness of removing the liquid paraffin from the surface of the fusion yarn precursor 5b. By removing the fusion yarn precursor 5b from the bath 71, a UHPE fusion yarn 5c is obtained with a predetermined amount of liquid paraffin adjusted to the yarn surface. After removal from the bath 71, the UHPE fusion yarn 5c may be dried, if necessary. The drying device 72 is not particularly limited, and examples thereof include a heating device such as an oven, and a blower that blows hot air or room temperature air. The obtained UHPE fusion yarn 5c is wound onto a yarn winding device 67.

[0030] <Modifications> The manufacturing apparatus 8 shown in FIG. 4 illustrates a case where the processes from fusing the UHPE multifilaments 5a to removing the liquid paraffin from the surface of the fusion yarn precursor 5b are performed in a single line, but this is not limited to this, and the processes may be performed separately in two or more lines. For example, as shown in FIGS. 6 and 7 , the manufacturing apparatus 8 has a first line 81 that produces the fusion yarn precursor 5b by fusing the UHPE multifilaments 5a, and a second line 82 that produces the UHPE fusion yarn 5c by removing the liquid paraffin from the surface of the fusion yarn precursor 5b. The first line 81 and the second line 82 are independent. The operation of the manufacturing apparatus 8 having the first line 81 and the second line 82 is basically the same as that of the apparatus 8 shown in FIG. 4. Briefly, as shown in FIG. 6 , the UHPE multifilament 5a serving as the raw yarn is reeled out from a yarn reeling device 61 and drawn while being fed from a first drawing device 62 to a second drawing device 66. Furthermore, between the first drawing device 62 and the second drawing device 66, the UHPE multifilament 5a is impregnated with liquid paraffin by an impregnation device 63, and excess liquid paraffin is removed by an excess removal device 64. The obtained fusion yarn precursor 5b is taken up by a yarn winding device 68. Subsequently, as shown in Figure 7, the fusion yarn precursor 5b is let out from a yarn letting-out device 69, and this fusion yarn precursor 5b is immersed in a bath 71 containing a removing liquid, and then dried in a drying device 72 as necessary. The obtained UHPE fusion yarn 5c is taken up by a yarn winding device 67.

[0031] [UHPE fusion yarn] The UHPE fusion yarn includes the above-mentioned UHPE multifilament and the above-mentioned liquid paraffin having an average molecular weight of 400 or more. In the UHPE fusion yarn, the liquid paraffin content is greater than 0% by weight and less than 13% by weight of the entire yarn. The liquid paraffin content refers to the content of all liquid paraffins contained in the UHPE fusion yarn, assuming the UHPE fusion yarn to be 100% by weight. Hereinafter, this liquid paraffin content may be referred to as the "total content." The total liquid paraffin content is preferably greater than 0% by weight and less than 8% by weight, more preferably 0.5% by weight to 5% by weight, and even more preferably 1.0% by weight to 5% by weight.

[0032] Furthermore, in the UHPE fused yarn, the content of liquid paraffin present on the yarn surface is greater than 0 wt% and not more than 10 wt%. Hereinafter, this liquid paraffin content may be referred to as the "surface content." The surface content of liquid paraffin is preferably greater than 0 wt% and not more than 6 wt%, more preferably 0.1 wt% to 5 wt%, and even more preferably 0.1 wt% to 2 wt%. Furthermore, in the UHPE fused yarn, the content of liquid paraffin present inside the yarn is preferably 0.1 wt% to 6 wt%, more preferably 0.3 wt% to 5 wt%, and even more preferably 0.4 wt% to 4 wt%. Hereinafter, this liquid paraffin content may be referred to as the "internal content."

[0033] Here, the total liquid paraffin content (the content of all liquid paraffins relative to the entire yarn) can be calculated using the formula: total content (wt%) = X / M x 100. X represents the weight of all liquid paraffins contained in the UHPE fusion yarn per unit length, and M represents the weight of the UHPE fusion yarn containing liquid paraffin per unit length. The weight of all liquid paraffins contained in the UHPE fusion yarn per unit length can be measured by component analysis of the UHPE fusion yarn. Alternatively, the total liquid paraffin content may be calculated using a simple measurement method. For example, the total liquid paraffin content can also be calculated using the formula: total content (wt%) = (M - N) / M x 100. M represents the weight per unit length of the UHPE fusion yarn containing liquid paraffin, and N represents the weight per unit length of the UHPE fusion yarn obtained by heat-drawing without impregnation with liquid paraffin (UHPE fusion yarn not containing liquid paraffin).

[0034] The surface content of liquid paraffin can be calculated using the formula: surface content (wt%) = (M - V) / M x 100. M represents the weight per unit length of the UHPE fusion yarn containing liquid paraffin, and V represents the weight of the UHPE fusion yarn after removing the liquid paraffin present on the surface of the UHPE fusion yarn of unit length. For example, V can be obtained by immersing a unit length of the UHPE fusion yarn in isopropyl alcohol for a predetermined time, drying it, and then measuring the weight of the UHPE fusion yarn. Specific methods for measuring the total content and surface content of liquid paraffin are described in the Examples below. The internal content of liquid paraffin can be calculated by subtracting the surface content from the total content.

[0035] FIG. 8 is a front view of the UHPE fusion yarn 5c with both ends omitted, and FIG. 9 is a cross-sectional view thereof. Note that FIG. 9 is a reference diagram that schematically illustrates the cross section of the yarn. As shown in FIG. 9, the UHPE fusion yarn 5c is formed by fusion bonding multiple UHPE monofilaments X to form a monofilament-like structure. The UHPE monofilaments X are shaded. Note that while FIG. 9 clearly illustrates the interfaces (boundaries) between adjacent UHPE monofilaments X, because multiple UHPE monofilaments X are fused together, the interfaces between adjacent UHPE monofilaments X may not appear clearly in reality. Note also that the drawn and fused UHPE monofilaments do not have a perfect circular shape in cross section. Liquid paraffin is present inside the UHPE fusion yarn 5c (inside the yarn). In other words, liquid paraffin is interposed between adjacent UHPE monofilaments. The liquid paraffin inside the yarn is not interposed between all adjacent UHPE monofilaments, but is interposed in places. Furthermore, liquid paraffin is attached to the surface (yarn surface) of the UHPE fusion yarn 5c. The liquid paraffin on the yarn surface does not cover the entire yarn surface, but is present in places. In Figure 9, the liquid paraffin present inside the yarn is marked with the symbol Y, and the liquid paraffin present on the yarn surface is marked with the symbol Z. The total amount of liquid paraffin is the sum of the amount of liquid paraffin inside the yarn and the amount of liquid paraffin on the yarn surface.

[0036] The single filament fineness of the UHPE fusion yarn is not particularly limited, but if it is too small or too large, the fusion properties may be reduced. From this viewpoint, the single filament fineness of the UHPE fusion yarn is preferably 0.7 dtex or more and 2.5 dtex or less, more preferably 0.7 dtex or more and 2.2 dtex or less, and even more preferably 1.0 dtex or more and 1.5 dtex or less. The single filament fineness of the UHPE fusion yarn refers to the value obtained by dividing the fineness of the UHPE multifilament (UHPE multifilament before fusion) by the draw ratio and then dividing this by the number of filaments.

[0037] When the UHPE multifilament is twisted, a twisted UHPE fusion yarn is obtained. In this case, the twist coefficient K2 of the UHPE fusion yarn is not particularly limited, but is preferably greater than 0 and not greater than 2200, more preferably 400 to 2100, and even more preferably 900 to 2050. A UHPE fusion yarn having a twist coefficient K2 within the above range has a knot strength ratio a / b in the range of 0.9 to 1.1. A UHPE fusion yarn having a knot strength ratio (a / b) of 0.9 to 1.1 has very little difference in yarn strength depending on the knotting method. A UHPE fusion yarn having a knot strength ratio within this range is suitable for use as a fishing line. The twist coefficient K2 of a UHPE fusion yarn obtained from a UHPE multifilament in the form of simply pulling together multiple UHPE monofilaments is zero. The twist coefficient K2 of a UHPE fusion yarn can be calculated using the following formula: K2 = t × D １／２ Here, t in the above formula 2 represents the number of twists (turns / m) of the UHPE fusion yarn, and D in the above formula 2 represents the weight (unit: grams) of the fusion yarn per 1000 m of length, obtained by excluding the amount of paraffin contained in the fusion yarn.

[0038] The UHPE fusion yarn of the present invention has excellent fusibility and a low coefficient of dynamic friction. Fusibility refers to the degree to which the individual monofilaments constituting the UHPE multifilament before fusion are bonded to each other by fusion. A UHPE fusion yarn with excellent fusibility has a monofilament-like structure. Therefore, the UHPE fusion yarn of the present invention has good water drainage, excellent surface smoothness, is resistant to fluffing when cut, and has excellent abrasion resistance.

[0039] [Technical Significance of the Present Invention] Liquid paraffin functions as an auxiliary agent for bonding filaments together during the production of UHPE fusion yarn. Specifically, the production of UHPE fusion yarn is carried out in the order of the impregnation step, fusion step, and removal step, as described above. In the impregnation step, the UHPE multifilament is impregnated with liquid paraffin. In the fusion step, the heated liquid paraffin partially dissolves the surfaces of the filaments, and by drawing, the filaments adhere to each other and fuse together in the dissolved portions. Liquid paraffin with an average molecular weight of 400 or more is thought to have excellent ability to dissolve the filaments. The role of liquid paraffin is thought to be to dissolve the filaments during heating and drawing in the fusion step. Therefore, it can be said that the greater the amount of impregnation with liquid paraffin, the more easily dissolution progresses, and a UHPE fusion yarn with excellent fusion properties can be provided.

[0040] However, it has been found that when a UHPE fusion yarn containing a large amount of liquid paraffin is used as a fishing line, the fusion yarn sticks to the guide of the fishing rod, making it difficult to cast farther, and the fusion yarn becomes frayed (the fraying is caused by some filaments in the multifilament unraveling). In this regard, liquid paraffin is thought to have the effect of lowering the dynamic friction coefficient, like a lubricant. For this reason, the inventors believed that a UHPE fusion yarn containing a large amount of liquid paraffin would be less likely to stick to the guide and would also be less likely to become frayed due to rubbing against the guide, etc.

[0041] After further intensive research, the inventors discovered that the liquid paraffin contained in the UHPE fusion yarn is present both inside and on the surface of the fusion yarn, and that the balance between the amount of liquid paraffin inside the yarn and the amount of liquid paraffin on the yarn surface is important. Specifically, as described above, the liquid paraffin present inside the yarn has the effect of dissolving the filaments during the production of the UHPE fusion yarn, but does not contribute to the fusion strength of the filaments. Therefore, the liquid paraffin present inside the manufactured UHPE fusion yarn does not enhance the fusion properties of the yarn. On the other hand, if a large amount of liquid paraffin is present inside the yarn, it may swell during use of the fusion yarn and embrittle the fused portions of the filaments. The embrittlement of the fused portions of the filaments causes the filaments to unravel, which causes fuzzing. Therefore, it is desirable for a UHPE fusion yarn whose fusion properties do not decrease over time to have a small amount of liquid paraffin present inside the yarn. Furthermore, it is estimated that the presence of a large amount of liquid paraffin on the yarn surface causes the surface to become sticky, increasing the dynamic friction coefficient of the UHPE fusion yarn. For these reasons, it is believed that a UHPE fusion yarn having a total liquid paraffin content of more than 0% by weight and not more than 13% by weight and a surface liquid paraffin content of more than 0% by weight and not more than 10% by weight will have filaments that are less likely to unravel even after long-term use (i.e., excellent fusion properties even over time) and a low dynamic friction coefficient. This effect is also evident from the following examples and comparative examples.

[0042] The UHPE fusion yarn of the present invention can be used for a variety of purposes, such as fishing line, fishing nets, and other marine materials, ropes, and strings for rackets. The UHPE fusion yarn has a low dynamic friction coefficient, which reduces friction with fishing rod guides and the like. For this reason, the UHPE fusion yarn is particularly suitable for use as fishing line.

[0043] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0044] <UHPE multifilaments used> Multifilament (1): A multifilament formed by twisting together 40 UHPE monofilaments and having a fineness of 85 dtex. Multifilament (2): A multifilament formed by twisting together 20 UHPE monofilaments and having a fineness of 55 dtex. Multifilament (3): A multifilament formed by twisting together 120 UHPE monofilaments and having a fineness of 275 dtex. Multifilament (4): A multifilament formed by twisting together 240 UHPE monofilaments and having a fineness of 440 dtex. Multifilament (5): A multifilament formed by twisting together 480 UHPE monofilaments and having a fineness of 880 dtex.

[0045] <Liquid paraffins used> Liquid paraffins: Four types of liquid paraffins with different average molecular weights as shown in the table, manufactured by MORESCO.

[0046] <Measurement of Molecular Weight of Liquid Paraffin> The average molecular weight of liquid paraffin was calculated in normal paraffin equivalent terms using a gas chromatograph (manufactured by Shimadzu Corporation, trade name "GC-2010") from a calibration curve of a standard substance, normal paraffin (manufactured by SIGMA-ALDRICH, trade name "ASTM 5442 (C12-C60) Quantitative Linearity Standard"). Specifically, the standard substance, normal paraffin (manufactured by SIGMA-ALDRICH, trade name "ASTM 5442 (C12-C60) Quantitative Linearity Standard"), was measured using a gas chromatograph (manufactured by Shimadzu Corporation, trade name "GC-2010"), and a calibration curve was created from the retention time of the peak value of the standard substance and the molecular weight of the standard substance. Next, the liquid paraffin to be measured was similarly measured using a gas chromatograph. According to the principles of chromatography, liquid paraffin migrates to the detector at a retention time corresponding to its molecular weight, and is then converted into an electrical signal by the detector. A chromatogram was obtained by plotting the time elapsed since the sample was introduced on the horizontal axis and the signal intensity obtained from the detector on the vertical axis, and the retention time of the peak value of this signal intensity was measured. The molecular weight of the liquid paraffin to be measured was determined from the retention time of this peak value and the above calibration curve. An example of the measurement conditions for the gas chromatograph is shown below. Detector type: FID. Column: Capillary column (manufactured by Frontier Labs, product name "Ultra alloy-SIMDIS (HT)"). Length: 10 m, inner diameter: 0.53 mm, film thickness: 0.1 μm. Carrier gas: Helium gas. Flow rate: 24.0 (ml / min), linear velocity: 140.5 cm / s. Initial column temperature: 35°C. Rate: 10° C. / min, final temperature: 410° C., detector temperature: 420° C. Injection method: total injection. Sample injection volume: 0.5 μl (microliter).

[0047] <Manufacturing Apparatus Used> A manufacturing apparatus 8 having independent first and second lines 81 and 82, as shown in FIGS. 6 and 7, was used. The impregnation device 63 and excess removal device 64 of the first line 81 of this manufacturing apparatus 8 were of the type shown in FIG. 5. That is, the impregnation device 63 brought a nonwoven fabric impregnated with liquid paraffin into contact with the surface of the UHPE multifilament, and the removal method of the excess removal device 64 brought a dried nonwoven fabric into contact with the surface of the UHPE multifilament. The impregnation device 63 was equipped with a supply unit 631 that continuously supplied liquid paraffin to the nonwoven fabric, and the supply unit 631 allowed the amount of liquid paraffin supplied to the nonwoven fabric to be arbitrarily set. In addition, the heating device 65 of the first line 81 was a radiant heat type consisting of two 5-m-long ovens connected together, and the stretching device was of a one-stage stretching type. The bath 71 of the second line 82 of this manufacturing apparatus 8 contained isopropyl alcohol, an organic solvent. The heating device 72 of the second line 82 was a single radiant heat oven having a length of 5 m.

[0048] Example 1 Multifilaments were loaded into the yarn unwinding device 61 of the first line 81 of the manufacturing apparatus 8, which was installed at room temperature (23°C), and liquid paraffin having an average molecular weight of 483 was supplied to the impregnation device 63 (see Figures 5 and 6). Multifilaments 5a were unwound from the yarn unwinding device 61, and the multifilaments 5a were brought into contact with an impregnation section 633 made of a nonwoven fabric of the impregnation device 63, thereby coating the multifilaments 5a with liquid paraffin. Thereafter, excess liquid paraffin was removed from the multifilaments 5a in an excess removal device 64. Furthermore, the multifilaments 5a were stretched while being heated to approximately 155°C in a heating device 65, thereby producing a fusion yarn precursor 5b. When the first line 81 was operated, the peripheral speed of the first stretching device 62 was set to 11.5 m / min and the peripheral speed of the second stretching device 66 was set to 24.2 m / min so that the stretching ratio would be about 2.1 times.

[0049] Next, the fusion yarn precursor 5b was loaded into the yarn payout device 69 of the second line 82 of the manufacturing apparatus 8, which was installed at room temperature (23°C) (see Figure 7). The fusion yarn precursor 5b was paid out from the yarn payout device 69 and passed through a bath 71 filled with isopropyl alcohol to incompletely remove liquid paraffin from the surface of the fusion yarn precursor 5b. The fusion yarn precursor 5b was then heated to approximately 100°C in a heating device 72 and taken up on a take-up device 67 to produce the UHPE fusion yarn of Example 1. In the second line 82, the feed speed of the fusion yarn precursor 5b was set to 20 m / min, and the fusion yarn precursor 5b was passed through the bath 71 for approximately 2 seconds. In Table 1, "MF" represents multifilament, and "FY" represents UHPE fusion yarn (the same applies to Tables 2 to 5 below).

[0050] Examples 2 to 7 and Comparative Examples 1 to 4 UHPE fusion yarns of Examples 2 to 7 and Comparative Examples 1 to 4 were produced in the same manner as Example 1, except that at least one of the contact pressure of the multifilament 5a with the impregnation section 633 of the impregnation device 63 and the time for which the fusion yarn precursor 5b was passed through the isopropyl alcohol bath 71 was changed. Note that, when the contact pressure of the multifilament 5a with the impregnation section 633 of the impregnation device 63 was increased, the amount of impregnation with liquid paraffin increased, and when the contact pressure was decreased, the amount of impregnation with liquid paraffin decreased. Furthermore, when the time for which the fusion yarn precursor 5b was passed through the isopropyl alcohol bath 71 was increased, the amount of liquid paraffin removed from the surface of the fusion yarn precursor 5b increased, and when the time was shortened, the amount of liquid paraffin removed from the surface of the fusion yarn precursor 5b decreased.

[0051] Example 8 A fusion-bonded UHPE yarn of Example 8 was produced in the same manner as in Example 1, except that liquid paraffin having an average molecular weight of 430 was used instead of liquid paraffin having an average molecular weight of 483.

[0052] [Examples 9 to 14 and Comparative Examples 5 to 8] The UHPE fusion yarns of Examples 9 to 14 and Comparative Examples 5 to 8 were each produced in the same manner as in Example 8, except that at least one of the contact pressure of the multifilament 5a against the impregnation section 633 of the impregnation device 63 and the time for which the fusion yarn precursor 5b was passed through the isopropyl alcohol bath 71 was changed.

[0053] Example 15 A fusible UHPE yarn of Example 15 was produced in the same manner as in Example 1, except that liquid paraffin having an average molecular weight of 409 was used instead of liquid paraffin having an average molecular weight of 483.

[0054] [Examples 16 to 21 and Comparative Examples 9 to 12] The UHPE fusion yarns of Examples 16 to 21 and Comparative Examples 9 to 12 were each produced in the same manner as in Example 15, except that at least one of the contact pressure of the multifilament 5a against the impregnation section 633 of the impregnation device 63 and the time for which the fusion yarn precursor 5b was passed through the isopropyl alcohol bath 71 was changed.

[0055] Comparative Example 13 A UHPE fusion yarn of Comparative Example 13 was produced in the same manner as in Example 1, except that liquid paraffin having an average molecular weight of 365 was used instead of liquid paraffin having an average molecular weight of 483.

[0056] [Comparative Examples 14 to 25] The UHPE fusion yarns of Comparative Examples 14 to 25 were each produced in the same manner as Comparative Example 13, except that at least one of the contact pressure of the multifilament 5a against the impregnation section 633 of the impregnation device 63 and the time for which the fusion yarn precursor 5b was passed through the isopropyl alcohol bath 71 was changed.

[0057] Comparative Example 26 A fusion-bonded UHPE yarn of Comparative Example 26 was produced in the same manner as in Example 1, except that the yarn was not impregnated with liquid paraffin.

[0058] [Examples 22 to 25] The UHPE fusion yarns of Examples 22 to 25 were each produced in the same manner as Example 1, except that MF (2) to (5) were used instead of MF (1) (see Table 5) and the peripheral speeds of the first drawing device 62 and the second drawing device were changed.

[0059] <Measurement of Total Liquid Paraffin Content in UHPE Fusion Yarn> The total liquid paraffin content in each UHPE fusion yarn obtained in each Example and Comparative Example was measured. Specifically, a 100 m length of the UHPE fusion yarn of Example 1 was cut out, and its weight was measured to the nearest 0.1 mg. Separately, a yarn (hereinafter referred to as control yarn) was produced in the same manner as Example 1, except that liquid paraffin was not applied. 100 m of this control yarn was cut out, and its weight was measured to the nearest 0.1 mg. The liquid paraffin content of the UHPE fusion yarn of Example 1 was then calculated by substituting the following formula. The results are shown in Table 1. Similarly, a 100 m length of each of the UHPE fusion yarns of Examples 2 to 25 and Comparative Examples 1 to 25 was cut out, and its weight was measured to the nearest 0.1 mg. Separately, a control yarn was produced in the same manner as Examples 2 to 25 and Comparative Examples 1 to 25, except that liquid paraffin was not applied. A 100 m length of each control yarn from Examples 2 to 25 and Comparative Examples 1 to 25 was cut out and its weight measured to the nearest 0.1 mg. The liquid paraffin content of the UHPE fusion yarns from Examples 2 to 25 and Comparative Examples 1 to 25 was then calculated by substituting the data into the following formula. The results are shown in Tables 1 to 5. Total liquid paraffin content (wt%) in the UHPE fusion yarn = (M - N) / M x 100, where M represents the weight of 100 m of the UHPE fusion yarn from each Example and Comparative Example, and N represents the weight of each 100 m of the control yarn.

[0060] <Measurement of Liquid Paraffin Content (Surface Content) Present on the Yarn Surface of UHPE Fused Yarn> The liquid paraffin content on the yarn surface of each UHPE fusion yarn obtained in each Example and Comparative Example was measured. Specifically, a 100 m length of the UHPE fusion yarn of Example 1 was cut out, and its weight was measured to the nearest 0.1 mg. The 100 m UHPE fusion yarn was immersed in 500 g of isopropyl alcohol at 20°C for 0.3 hours, then removed and dried at 70°C for 10 minutes. By immersing the yarn in the removal solution, isopropyl alcohol, for 0.3 hours, the liquid paraffin present on the surface of the UHPE fusion yarn can be almost completely removed. Hereinafter, the UHPE fusion yarn from which the liquid paraffin on the surface has been completely removed is referred to as the "removed yarn." The weight of the 100 m removed yarn after drying was measured to the nearest 0.1 mg. The surface content of liquid paraffin of the UHPE fusion yarn of Example 1 was calculated from the weight of the UHPE fusion yarn and the weight of the removed yarn. The results are shown in Table 1. Similarly, 100 m of each UHPE fusion yarn from Examples 2 to 25 and Comparative Examples 1 to 25 was cut out, and its weight was measured to the nearest 0.1 mg. Each 100 m of UHPE fusion yarn from Examples 2 to 25 and Comparative Examples 1 to 25 was immersed in 500 g of isopropyl alcohol at 20°C for 0.3 hours, then removed and dried at 70°C for 10 minutes. The weight of the 100 m of removed yarn after drying was measured to the nearest 0.1 mg. The surface content of liquid paraffin in the UHPE fusion yarns from Examples 2 to 25 and Comparative Examples 1 to 25 was calculated from the weight of the UHPE fusion yarn and the weight of the removed yarn. The results are shown in Tables 1 to 5. Surface content of liquid paraffin in UHPE fusion yarn (wt%) = (M - V) / M x 100. where M represents the weight of 100 m of UHPE fusion yarn in each example and comparative example, and V represents the weight of each 100 m of removed yarn. Tables 1 to 5 also list the internal content (content of liquid paraffin present inside the yarn). The internal content (wt%) was calculated by subtracting the surface content from the total content.

[0061] <Evaluation of fusion properties of UHPE fusion yarns> The surface of each UHPE fusion yarn obtained in each example and comparative example was visually observed, and each fusion yarn was rubbed vigorously with a finger to evaluate the degree of fusion of the filaments and further evaluate its suitability as fishing line. The results are shown in the table. AA: The surface of the fusion yarn was sufficiently smooth. Each monofilament was sufficiently fused, and the fusion yarn did not come apart. It can be used very suitably as fishing line. A: The surface of the fusion yarn was sufficiently smooth. Each monofilament was sufficiently fused, and the fusion yarn hardly came apart. It can be used suitably as fishing line. B: The surface of the fusion yarn was smooth. Parts of the fusion yarn (one or two parts per 100 m) came apart slightly, and separated into several monofilaments in those parts. It can be used as fishing line. C: Some unevenness was observed on the surface of the fusion yarn. Many parts of the fusion yarn (three or more parts per 100 m) came apart, and separated into several monofilaments in those parts. It may be usable as a fishing line. D: The monofilaments that make up the multifilament were not fused, and the monofilaments were loose in all areas, not forming a fused thread. It can be evaluated as not usable as a fishing line.

[0062] <Measurement of dynamic friction coefficient of UHPE fusion yarn> The dynamic friction coefficient of each UHPE fusion yarn obtained in each example and comparative example was measured in accordance with JIS L 1015 (2010)-8.13. The measurement device used was a yarn dynamic friction coefficient measuring device manufactured by Daiei Kagaku Seiki Seisakusho. The dynamic friction coefficient μK can be calculated using the following formula. The results are shown in the table. Note that the smaller the dynamic friction coefficient value, the smaller the friction resistance and the easier it is to evaluate the slipperiness. Formula: μK = 0.733 log W / (W-R) W: load (g) applied to both ends of the yarn R: U gauge reading (g)

[0063] <Evaluation of Thread Stickiness> The stickiness of each UHPE fusion thread obtained in each Example and Comparative Example was evaluated as follows. The UHPE fusion thread was wound onto a fishing spool. Next, as shown in FIG. 10 , a shaft member was fitted into the hole in the center of the spool, the shaft member was held horizontally, and the shaft member of the spool around which the UHPE fusion thread was wound was held with one hand. The spool was rotated around its axis in the direction opposite to the winding direction of the fusion thread. When the spool was rotated in this manner, the state of the wound fusion thread unwinding from the spool was evaluated according to the following criteria. The results are shown in Tables 1 to 5. When the thread unwound and came out as the spool rotated, the stickiness was evaluated as "absent." When the end of the fusion thread did not unwind and rotated with the spool, the stickiness was evaluated as "present." Note that when a fusion thread with no stickiness was used as fishing line, the resistance to release from the spool was small. For this reason, it can be evaluated as a fusible thread that can be cast farther when cast.

[0064] <Evaluation of Handling of UHPE Fused Yarn> The UHPE fused yarns obtained in each Example and Comparative Example were evaluated for ease of handling when used as fishing lines. The results are shown in Tables 1 to 5. ∘: When the fused yarn was used as a fishing line and a lure was cast toward the water surface, the frictional resistance between the fishing line and the fishing rod guide was low, allowing the line to be cast farther. Furthermore, during 100 castings per day, the fishing line did not break or become tangled in the fishing rod guides. ×: When the fused yarn was used as a fishing line and a lure was cast toward the water surface, the frictional resistance between the fishing line and the fishing rod guides was high, preventing the line from being cast very far. Furthermore, during 100 castings per day, the fishing line broke or became tangled in the fishing rod guides at least once.

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] The results of Examples 1 to 25 show that UHPE fusion yarns having a total content of liquid paraffin with an average molecular weight of 400 or more that is greater than 0 wt% and less than 13 wt%, and a surface content of liquid paraffin with an average molecular weight of 400 or more that is greater than 0 wt% and less than 10 wt%, have good fusion properties, a low dynamic friction coefficient, and excellent handleability as fishing lines. In particular, a comparison of Examples 1 to 14 with Examples 15 to 21 shows that Examples 1 to 14, which contain liquid paraffin with a molecular weight of 420 or more, have even better fusion properties. Furthermore, the results of Comparative Examples 1 to 12 show that even when liquid paraffin with an average molecular weight of 400 or more is used, if the total content of liquid paraffin exceeds 13 wt% and / or the surface content of liquid paraffin exceeds 10 wt%, the dynamic friction coefficient is high and the yarn's stickiness and handleability are poor. The poor handleability is presumably due to swelling of the liquid paraffin present in the fusion portion inside the yarn during casting, causing embrittlement. Furthermore, when the liquid paraffin on the surface is 0%, as in Comparative Example 24, even if the dynamic friction coefficient is small, localized destruction and fuzzing rapidly progress due to the almost complete absence of paraffin on the thread surface, making the fused thread more likely to become tangled in the fishing rod guides and reducing handleability.

[0071] The ultra-high molecular weight polyethylene fusion yarn of the present invention can be used for fishery materials such as fishing lines, fishing nets, and longlines for leisure or fishing use, industrial materials such as ropes and kite lines, sports materials such as guts for tennis rackets and bowstrings, musical instrument materials such as guitar strings, and threads for forming protective clothing. In particular, the ultra-high molecular weight polyethylene fusion yarn of the present invention can be suitably used as fishing lines for leisure or fishing use.

[0072] 21, 22, 23, 5a Ultra-high molecular weight polyethylene multifilament 3 Ultra-high molecular weight polyethylene monofilament 5b Fusion yarn precursor 5c Ultra-high molecular weight polyethylene fusion yarn 6 Ultra-high molecular weight polyethylene fusion yarn manufacturing apparatus

Claims

1. A fused yarn comprising ultra-high molecular weight polyethylene multifilament and liquid paraffin having an average molecular weight of 400 or more, wherein the liquid paraffin content of the entire yarn is greater than 0% and less than 13% by weight, and the liquid paraffin content present on the surface of the yarn is greater than 0% and less than 10% by weight.

2. The ultra-high molecular weight polyethylene fusion yarn as described in claim 1, wherein the liquid paraffin content is greater than 0% by weight and less than 8% by weight relative to the entire yarn, and the liquid paraffin content present on the yarn surface is greater than 0% by weight and less than 6% by weight.

3. The ultra-high molecular weight polyethylene fusion yarn as described in claim 1, wherein the liquid paraffin content is greater than 0% by weight and less than 5% by weight relative to the entire yarn, and the liquid paraffin content present on the yarn surface is greater than 0% by weight and less than 2% by weight.

4. The ultra-high molecular weight polyethylene fusion yarn according to claim 1, wherein the fusion yarn has a fineness of 10 dtex or more and 500 dtex or less.

5. A method for producing an ultra-high molecular weight polyethylene fused yarn as described in claim 1, comprising the steps of: impregnating an ultra-high molecular weight polyethylene multifilament with liquid paraffin having an average molecular weight of 400 or more; obtaining a fused yarn precursor by heating and stretching the ultra-high molecular weight polyethylene multifilament containing the liquid paraffin; and removing the liquid paraffin present on the surface of the fused yarn precursor by contacting the fused yarn precursor with a removal liquid.

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