JP2004169267A - Hyperbaric, high strength conjugate fiber and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber having both of high sinkable property and fiber strength sufficient to net making processing, excellent in light-resistance causing no strength deterioration after long term use as a fishing net and having color tone causing no sense of imcompatibility for fishes. <P>SOLUTION: The conjugate fiber has ≥1.5 fiber specific gravity and ≥3.5 g/dr strength and comprises a core component and a protective component, wherein the core component comprises polyamide containing 50-85 wt.% magnetite powder and titanium dioxide powder in total and the protective component comprises polyester containing a colorant and having ≥0.7 [η]. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a conjugate fiber having both high specific gravity and high strength and suitable for use in industrial materials, and particularly to a conjugate fiber suitable for fishnets having no problem of marine environmental pollution and excellent in durability.

  Conventionally, fiber for fishery materials used in fish nets has been focused on high sedimentation speed of fish nets in seawater and shape retention against tidal currents. It is known that a fish net with a small supplement angle and good shape retention can be obtained. In particular, in the case of a fixed net, since the shape of the fish net in the sea relative to the school of fish greatly affects catching, a fiber having a large specific gravity, good drainage, and good wear resistance has been required. Moreover, as the color hue of the fiber, a black color tone that does not give a sense of caution to the fish and does not give a sense of incongruity is required.

  From this viewpoint, in the past, vinylidene chloride-based fibers having a relatively large specific gravity have been widely used, but high-strength fibers that can be stably provided for high-speed net-making with the development of net-making technology. As a result, vinylidene chloride-based fibers have a problem of insufficient strength. In addition, there is a problem that when a pigment is added to color the fibers, the strength of the fibers is further reduced.

  In order to solve such problems, fibers for fishery materials having both high specific gravity and high strength have been developed, and various fibers have been proposed. As one of the means, a fiber obtained by combining a resin exhibiting high strength by drawing and a high specific gravity powder is considered. Specifically, (1) a fiber obtained by uniformly dispersing a high specific gravity powder in a resin (For example, JP-B-51-37378, JP-A-56-61936, JP-A-61-613), (2) A high specific gravity powder is mixed and dispersed in a resin having a low softening point, and this mixture is mixed. Further, a fiber obtained by mixing with a resin for imparting strength (Japanese Patent Publication No. 57-20407) and (3) a mixture of a resin having a low softening point and a powder having a high specific gravity are used as a core layer, and the resin for giving strength is used as a sheath layer. Cored fibers (JP-A-58-4819 and JP-A-62-15327) have been proposed.

However, at present, even with the above-mentioned materials, the high sedimentation speed and high-speed net-making properties required for fish netting fibers have not yet been sufficiently satisfied. Moreover, depending on the type of the high specific gravity powder used, the weather resistance is insufficient, and the resin constituting the fiber is deteriorated by being irradiated with sunlight for a long period of time, and as a result, the strength is significantly reduced, and as a fish net, There was a problem that it became impossible to use. Also, when metallic lead or its compound is used as the high specific gravity powder, the lead compound or the like may fall off from the fiber due to friction with the guide in the fiber manufacturing process or processing process, or may elute into seawater during use as a fish net and lead. Pollution problems could occur. Further, when the used fish net is discarded, there is a possibility that a similar pollution problem may occur such that harmful components including lead remain after incineration, and there is a problem that the fish net cannot be easily disposed of. In addition, fishing nets made of vinylidene chloride fiber containing no lead also have a problem in that incineration is difficult because hydrogen chloride gas is generated during incineration.
JP-A-58-4819 JP-A-62-15327

  An object of the present invention is to provide a fiber which has both high sedimentation speed and sufficient fiber strength with no problem in net processing, and has excellent weather resistance which does not cause a decrease in strength even when used as a fish net for a long time. is there. It is still another object of the present invention to provide a fiber which satisfies such characteristics and has a color tone which does not cause uncomfortable feeling to fish.

  That is, the first invention of the present invention comprises a core polymer component containing 50 to 85% by weight of fine particles made of a lead-free metal or a compound thereof having a specific gravity of 3 or more, and a protective polymer component covering the core polymer component, The second invention is a conjugate fiber having a fiber specific gravity of 1.5 or more and a strength of 3.5 g / d or more, and a total of 50 to 85 in total of titanium dioxide and other inorganic fine particles having a specific gravity of 3 or more. % By weight of a thermoplastic polymer having a melting point or softening point higher than that of the thermoplastic polymer by at least 20 ° C. as a protective component. A method for producing a conjugate fiber in which a heat treatment is performed at a temperature of not less than (melting point or softening point -80) ° C of the polymer and not more than (melting point or softening point -5) ° C of the thermoplastic polymer as the protective component. That.

  The fiber of the present invention has a specific gravity of 1.5 or more and a strength of 3.5 g / d. When the specific gravity is less than 1.5, the fiber has high sedimentation in seawater and shape retention of a fishing net. It is difficult to achieve this, and if the strength is less than 3.5 g / d, the fibers are damaged during high-speed netting, which is not preferable. From such a viewpoint, a fiber having a specific gravity of 1.55 or more and a strength of 4.0 g / d or more is desired. In the present invention, in order to increase the specific gravity of the fiber, it is essential to contain the fine particles having a specific gravity of 3 or more. As the type of the fine particles, fine particles of a lead-free metal or fine particles of a compound thereof are used. Must. In the present invention, the “lead-free metal” means a metal other than a metal that is very likely to cause environmental problems such as lead and tin, and specifically, titanium, iron, copper, zinc, silver, barium, zirconium. , Manganese, antimony, tungsten, and other metals and compounds such as oxides thereof.

  In the case where fine particles having a specific gravity of less than 3 are used, the content of the fine particles in the fibers must be increased and the composite ratio of the core polymer component must be increased in order to achieve the target fiber specific gravity. Even if a fiber having a specific gravity of fiber is obtained, the processability such as spinnability and stretchability is poor, and only a fiber having a low fiber strength can be obtained, which is not suitable for use as a fishing net.

  The content of the fine particles in the core polymer component must be 50 to 85% by weight. If the amount is less than 50% by weight, the composite ratio of the core polymer component (B) must be increased in order to obtain the desired fiber specific gravity, and only a fiber having a low fiber strength is obtained, which is not preferable. On the other hand, if it exceeds 85% by weight, the polymer melt fluidity at the time of spinning becomes poor and yarn breakage occurs frequently, which is not preferable.

  Next, it is desirable that the average particle diameter of the primary particles is 5 μm or less. If it is 5 μm or more, it is not preferable because thread breakage and fluff are likely to occur frequently during spinning and stretching. Further, it is preferable that the average particle diameter of the primary particles is 0.05 μ or more. If the particle size is too small, on the other hand, when adding the fine particles into the polymer, the heat generated during the molding process will cause thermal aggregation to form coarse particles. This is not preferable because the thermal aggregation of the fine particles is likely to occur in the pipe, and the trouble that the line is clogged frequently occurs.

  The type of fine particles to be used can be appropriately selected from the above fine particles as desired, but in the present invention, it is particularly significant to use iron oxide or titanium dioxide as the fine particles.

First, the case where iron oxide is used will be described. Iron oxide includes magnetite having a black color, that is, magnetite (Fe ₃ O ₄ ), brown γ-type hematite, reddish-brown α-type hematite, and the like. Then, since the fish does not give a sense of caution, it is possible to give a good result to the fish catch, and it is preferable to use magnetite which exhibits black color. At this time, it is desirable that 20% by weight or more of the whole fine particles used are magnetite. The use of magnetite can simplify or omit the dyeing treatment and the like, but even in such a case, the use of a soaked polymer as the protective polymer component does not pose any problem.

  In addition, as the particle shape of magnetite, there are spherical, octahedral, hexahedral, polyhedral, etc., and any shape can be used, but the use of spherical magnetite fine particles provides the best dispersibility in the core polymer component. preferable. In particular, the use of these spherical particles has a remarkable effect when fine particles are added to a polymer at a high addition rate of several tens of percent or more as in the present invention. Is less likely to cause filter clogging, and is less likely to break during spinning and stretching.

  Furthermore, it is preferable to use, as the magnetite fine particles, fine particles subjected to a surface coating treatment with an organic or inorganic compound, since the heat resistance and the fine particle dispersibility can be further improved. It is particularly preferable to use magnetite coated with silica or ferrite coated on the surface of the fine particles.

  The fine particles to be added to the core polymer component may be magnetite fine particles alone. However, when the content of the magnetite fine particles in the core polymer component is 50% by weight or more, even if an appropriate particle shape and particle size are used, Contamination may occur due to thermal agglomeration in the line at the time of melt extrusion, and if severe, troubles such as clogging of pipes may occur. The content of fine particles in the core polymer component should be 50% by weight or more. Therefore, it is preferable to use magnetite in combination with other fine particles.

  In particular, in the case of producing fine denier yarn, the residence time of the molten polymer in the line is prolonged, and line clogging is significantly caused. Other fine particles used in combination with magnetite should have a specific gravity of 3 or more, an average particle diameter of 5 μm or less, have little heat cohesion, and be inexpensive. For example, preferable examples include titanium dioxide, zinc oxide, barium sulfate, alumina, ferrite, lithopone, copper oxide, and magnesium oxide.

  Heavy metal-based inorganic substances such as lead-based compounds such as lead tin and tin-based compounds such as tin oxide are large and suitable for the specific gravity of the particles, but are not preferable in terms of toxicity and the like. In particular, when used, it is difficult to dispose of fishing nets and the like, and in some cases, secondary pollution such as environmental pollution occurs, which is not preferable. In addition, tungsten-based inorganic particles and bismuth-based inorganic particles are high specific gravity particles, and are preferable inorganic particles in order to develop target performance and the like, but are very expensive and should be used for fishing net applications. Is difficult.

  In the present invention, titanium dioxide is most preferable among the inorganic particles that can be used in combination with the magnetite fine particles. Even if the mixing ratio of titanium dioxide with magnetite is arbitrarily changed within a range of 50% by weight to 85% by weight of the total fine particles with respect to the core polymer component, spinning properties and stretchability are good and no major trouble occurs. Although the desired fiber can be obtained, examples of suitable mixing ratios include, for example, when the total fine particle content in the core polymer component is 70% by weight, magnetite is 30% by weight, and titanium dioxide is When the content is 40% by weight or the total fine particle content in the core polymer component is 60% by weight, the mixing ratio of magnetite to 30% by weight and titanium dioxide to 30% by weight is obtained. Is also preferred. A preferred range of the mixing ratio of magnetite and titanium dioxide is magnetite / titanium dioxide = 2/8 to 7/3.

  When the content of fine particles in the polymer is a high content of 50% by weight or more and magnetite is added at a high content, by mixing and adding titanium dioxide particles, troubles such as line clogging during melt extrusion can be prevented. The inventors of the present invention have seen for the first time that the present inventors have obtained a desired fiber in a state in which the desired fiber is obtained in a state in which there is no dispersibility in the polymer, the yarn breakage during the process is small, and the A rating is high. It was issued.

  Next, the case where titanium dioxide is used will be described. An object of the present invention is to provide a netting fiber having both excellent mechanical properties and a high specific gravity, and at the same time, to provide a fishing net fiber capable of coping with various hues. When a high content of such colored particles is blended, the hue cannot be freely changed, but titanium dioxide is white, and such white particles are added to the core polymer component. By mixing a pigment of a desired color or the like, a desired color can be developed without being disturbed by the color of the core component.

  Titanium dioxide has three forms, anatase, rutile, and brookite, depending on the crystal form. Anatase and rutile are commonly used as pigments. In particular, the anatase type is mainly used for the chemical fiber due to the relationship between the hardness of the titanium dioxide in the process and the dispersibility in the solvent or the dispersion medium, and the specific gravity of the anatase type is 3.9. On the other hand, since the specific gravity of the rutile type is as large as 4.2, rutile type titanium dioxide is preferably used for the purpose of the present invention.

  In this case, the Mohs' hardness is higher in the rutile type than in the anatase type, and there is a concern that troubles such as abrasion in the process may occur. However, in the composite fiber of the present invention, the core polymer component containing fine particles is substantially a protective polymer component. Since it is covered in a specific manner, there is no problem such as abrasion of the nozzle base during spinning or abrasion damage of guides and rollers during the working process.

  Furthermore, when compared with other fine particles, titanium dioxide is added to a polymer in a high amount, and when the polymer is melt-extruded, thermal aggregation is less likely to occur, and clogging due to contamination in a molten polymer line is less likely to occur. It is preferable to use titanium dioxide rather than using other white-based fine particles since the filter is less likely to be clogged and the occurrence of yarn breakage during spinning and drawing is small.

  Titanium dioxide may be used alone, or part of it may be replaced with another white fine particle having a specific gravity of 3 or more and an average particle size of 5 μm or less. However, because of the problem of thermal aggregation as described above, it is desirable to use at least 15% by weight, particularly preferably 40% by weight, of titanium dioxide. As other white fine particles, for example, zinc oxide, alumina, barium sulfate, lithopone, magnesium oxide, and the like, which are less toxic than tin oxide (tinite), can be used.

  Next, as the base polymer of the core polymer component to which fine particles are added, a thermoplastic polymer having heat resistance at the spinning temperature of the protective polymer component is used. For example, nylon 6, nylon 66, nylon 610, nylon 12, nylon 11 , Nylon 4, Nylon 46 and other polyamides, polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate and other polyesters, polyethylene, polypropylene and other polyolefins, SBS (polystyrene-polybutadiene-polystyrene block copolymer) hydrogen Additive, hydrogenated product of SIS (polystyrene-polyisoprene-polystyrene block copolymer), hydrogenated product of SI (polystyrene-polyisoprene block copolymer), poly α-methyl Styrene - polyisoprene - can be appropriately selected from poly α- methyl styrene block copolymer aromatic vinyl block and a conjugated diene block copolymers and hydrogenated products of such.

  In particular, when fine particles are highly added as in the present invention, a base polymer having excellent wettability between the fine particles and the polymer and dispersibility of the particles in the polymer, and excellent spinnability and stretchability is used. From this viewpoint, it is desirable to use polyamides, particularly polyamides containing nylon 6 as a main component in the present invention.

  Further, the degree of polymerization of the nylon 6 base polymer used as a preferred example is about 22,000 or less in number average molecular weight, more preferably 20,000 or less and 6,000 or more. If the degree of polymerization is too high, the melt viscosity at the time of preparing the kneaded polymer when the fine particles are added at a high level becomes too high, which tends to cause troubles and poor dispersion. In addition, when melt-extruding and fibrillating a polymer to which inorganic particles are added in a high amount, if the melt viscosity is too high, troubles in equipment are liable to occur frequently and, at the same time, thread breakage frequently occurs, which is not preferable. On the other hand, if the degree of polymerization is too low, the melt viscosity becomes too low with respect to the protective polymer component, making it difficult to form a core-sheath cross section. In addition, when polyamide is used as the core polymer component, the core component containing inorganic fine particles must have a water content of 500 ppm or less, preferably 300 ppm or less. If a large amount of fine particles are contained in a water-absorbing polymer such as polyamide, when the moisture content is high, the fluidity is extremely lowered at the time of melting, which significantly impairs the process condition. Generally, polyamides not containing a large amount of fine particles are used at about 500 to 1000 ppm, whereas in the present invention containing a large amount, special consideration must be given. Further, the polyamide as the core polymer component may be copolymerized with a small amount of the third component, or may contain a small amount of additives, stabilizers and the like.

  The main use of the fiber of the present invention is for fishing nets.However, since fishing nets are used outdoors, weather resistance over time is important. Those that are problematic cannot be used. In the case of using a polyamide to which a large amount of the fine particles as described above is added, a decrease in fiber strength may occur when used as a fishing net for a long time. By adding 0.01% by weight or more, particularly 0.1% by weight or more and 2% by weight or less of a copper salt such as copper iodide as a heat stabilizer, the decrease in fiber strength over time is improved to a level that does not cause a practical problem. Is done. Further, when titanium dioxide is used as the fine particles, it is preferable to add an antioxidant or the like, since excitation of titanium atoms by ultraviolet rays easily promotes deterioration of the polymer.

  Various methods can be used as a method for incorporating the fine particles into the base polymer as the core polymer component. For example, a twin-screw extruder or the like is preferable. When the base polymer and the fine particles are kneaded, it is preferable to add various dispersants such as a metal stearate, a silane-based coupling agent, and a titanium-based coupling agent since the dispersibility becomes good.

  The conjugate fiber of the present invention can be obtained by conjugate spinning using a core polymer component containing fine particles as described above as one component and a protective polymer component which is a fiber-forming thermoplastic polymer as another component. As the composite cross-sectional shape, it is desirable that the protective polymer component occupies 60% or more, preferably 80% or more, particularly preferably 100%, of the fiber surface circumference. Various examples of the composite form of the core polymer component and the protective polymer component include various ones, and typical ones as shown in FIGS. 1 (1) to (8).

  In FIG. 1, (1) is a single-core fiber, (2) is a three-core fiber, (3) is a four-core core-sheath structure fiber, (4) is a three-layer concentric circle, and (5) and (6) are partially exposed types. And (7) and (8) are split-type composite structures. Depending on the combination of the core polymer component and the protective polymer component, the structures of (7) and (8) may peel off at the interface between the two components, and the structures of (5) and (6) may be a guide or a roller. Friction cannot be sufficiently eliminated. From the point that friction and thread breakage of guides and rollers can be further prevented and separation between polymers can be prevented, the core polymer such as (1) to (4) is completely covered with the protective polymer. A core-sheath structure is preferred. In these figures, the hatched portion is the core polymer component, and the portion without the hatched portion is the protective polymer component.

  The composite weight ratio of the protective polymer component and the core polymer component is 30:70 to 80:20, more preferably 50:50 to 80:20. If the ratio of the protective polymer component is too small, the fiber strength is undesirably reduced. On the other hand, if the ratio of the protective polymer component is too large, the effect of increasing the fiber specific gravity cannot be sufficiently exerted, which is not preferable.

  The protective polymer component of the present invention is not particularly limited as long as it is a thermoplastic polymer having a fiber-forming ability, such as polyester, polyamide, and polyolefin.In terms of practical performance as a fiber, polyethylene terephthalate and polybutylene terephthalate are the main components. Is preferred. Further, those obtained by copolymerizing a small amount of the third component with these polymers can also be used. For example, polyesters include terephthalic acid, isophthalic acid, naphthalene-2,5-dicarboxylic acid, α, β- (4-carboxyphenoxy) ethane, 4,4′-dicarboxydiphenyl, alkylene oxide adduct of bisphenol A, adipic acid , Azelaic acid, sebacic acid, trimellitic acid, ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, pentaerythritol, cyclohexane-1,4-dimethanol, polyethylene Fiber-forming properties synthesized from aromatic, aliphatic, and alicyclic dicarboxylic acids such as glycol, polytetramethylene glycol, and sodium salts of 5-sulfoisophthalic acid, diols, and oxycarboxylic acids such as hydroxybenzoic acid The polyester polymer is preferably a polyester polymer in which 80 mol% or more, particularly 90 mol% or more of the constituent units are ethylene terephthalate units or butylene terephthalate units. Further, these polymers may contain additives such as a fluorescent whitening agent and a stabilizer.

  In particular, carbon black may be contained in order to maintain the weather resistance of the entire fiber, that is, the strength retention over time at a better level. An important requirement when using a polyester-based polymer as the protective polymer component is to use a polymer having an intrinsic viscosity [η] of 0.7 or more. Here, the intrinsic viscosity [η] is a value measured at a temperature of 30 ° C. using a 50:50 mixed solution of phenol and tetrachloroethane.

  In ordinary clothing fibers, polyethylene terephthalate has a [η] of about 0.60 to 0.65, whereas the present invention employs ordinary polymerization to develop the desired fiber strength. A polyester having a higher degree of polymerization than that of the polyester is used. When [η] is less than 0.7, it is difficult to achieve both a fiber specific gravity of 1.5 or more and a fiber strength of 3.5 g / dr or more, and the composite ratio of the protective polymer component and the core polymer component is changed to increase the protective polymer component richness. In this case, the specific gravity of the fiber could not reach the target level, and when the core polymer component was rich, the fiber strength did not reach the target level. That is, by using a polyester having a protective polymer component having a [η] of 0.7 or more, a polyester satisfying both the fiber strength and the fiber specific gravity was obtained for the first time.

  [Η] in the present invention is [η] of the polyester component in which the fiber after spinning is formed. That is, when the degree of polymerization is reduced by thermal decomposition or hydrolysis during spinning, it is needless to say that the fiber must be formed using a polymer having a slightly higher degree of polymerization in consideration of the degree.

  By the way, in the present invention, a colorant is added to the protective polymer component to obtain a hue suitable for fishing net use as described above, and an organic pigment having heat resistance capable of withstanding the melt spinning temperature of the polymer component. And inorganic pigments can be used as appropriate. Specifically, for example, ordinary colorants for original wearing such as carbon black, anthraquinone-based brown colorant, anthraquinone-based purple colorant, and benzoquinone-based red colorant can be used. These pigments can be used alone or in combination of two or more. It is sufficient to mix the protective polymer component with the protective polymer component at an addition ratio of about 0.1 to 5% by weight.

  When the amount of the coloring agent is less than 0.1% by weight, it is difficult to obtain a netted yarn for fishing nets exhibiting a sufficient "color" or "gloss", and when it exceeds 5% by weight, the strength is greatly reduced. Is not preferred.

  In particular, most of the hue of the currently required netting yarn for fishing nets is black. In such a case, it is preferable to add 1 to 3% by weight of carbon black to the protective polymer component. This is because carbon black has an effect of absorbing ultraviolet rays to prevent deterioration of the polymer, and can prevent a decrease in the light resistance of the fiber, that is, the strength over time, and exhibit a synergistic effect.

  The method for obtaining the conjugate fiber of the present invention is not particularly limited, but the protective polymer component and the core polymer component are heated and melted in separate melting systems, and each is heated to a spinneret by a normal extrusion spinning apparatus. Immediately before feeding and spinning, both components are combined according to the composite shape as described above, and the yarn obtained by extrusion is wound up, further stretched and heat-treated. In addition, a method of immediately stretching without being wound after being extruded from a spinneret, or a method of extruding from a spinneret, winding at a high speed, and directly forming a product can also be used.

  Specifically, it is drawn at a speed of about 4000 m / min or less, and is wound and then stretched once, so-called FOY or POY stretching method, or a spin draw method of stretching without winding, and further, at 4000 m / min or more. In the DSY method for drawing at a high speed, or a method in which a heater is provided between the nozzle and the take-up roller in the DSY method, drawing is performed while stretching is applied. Among them, a method of drawing at 300 to 4000 m / min, more preferably 600 to 2000 m / min, stretching (either FOY or spin draw), and subsequently performing a heat treatment are preferable. When the speed is less than 300 m / min, the degree of orientation of the undrawn yarn is low, and it is necessary to increase the drawing ratio in order to obtain a desired fiber strength. As a result, a large number of voids are generated in the fiber and the specific gravity is increased. In some cases, this cannot be achieved sufficiently. On the other hand, in the case of drawing in a so-called DSY area exceeding 4000 m / min, the target physical properties may be obtained without performing the stretching heat treatment operation. It is inevitable that the strength decreases.

  The stretching may be one-stage stretching or two-stage stretching. The stretching ratio varies depending on the spinning speed and cannot be uniquely specified. However, it is preferable to employ a ratio of approximately 75 to 85% of the ratio leading to breakage. In particular, a characteristic point in the production of the fiber of the present invention is a heat treatment after drawing. That is, heat treatment is performed at a temperature of not less than (melting point or softening point -80) ° C of the thermoplastic polymer of the core component and not more than (melting point or softening point of -5) ° C of the thermoplastic polymer of the protective component. The higher the fiber is, the higher the fiber specific gravity and the higher the toughness. This is because the fibers are shrunk by heating at a temperature close to or above the melting point or softening point of the core polymer component, and voids in the polymer around the fine particles in the fiber generated during drawing are repaired to some extent. It is presumed that the crystallization of the protective component for developing the mechanical properties of the fiber is promoted by increasing the processing temperature. If the temperature of the heat treatment exceeds the (melting point or softening point -5) C of the polymer of the protective component, the yarn breaks frequently, and if the temperature is less than the melting point or softening point of the polymer of the core component -80C, the voids are sufficiently repaired. It is difficult. The lower limit of the preferable heat treatment temperature is (melting point or softening point −60) ° C. of the core component thermoplastic polymer, and the upper and lower limits are (melting point or softening point −10) ° C. of the protective component thermoplastic polymer. . For example, when the core polymer component is nylon 6 and the protective polymer component is polyester, the temperature of the heat treatment is desirably 160 ° C. or more and 255 ° C. or less.

  Further, in order to stabilize the stretching and suppress the generation of voids, in addition to the contact heating method such as a heat roll, the non-contact heating method such as steam jet or air heating is used in addition to the heating during the stretching. Is preferred. This is intended to be stretched at a temperature sufficiently higher than the core polymer component while increasing the fluidity of the core polymer. For example, when the core polymer component is nylon 6, it is 350 ° C. or more, preferably 400 ° C. As described above, it is particularly preferable to perform heat stretching using a steam jet at 430 ° C. or higher. Note that the temperature of the steam jet does not indicate the heat treatment temperature in the present invention, but the heat treatment temperature in the present invention means a contact heating temperature. Based on these findings, it is preferable that the base polymer as the core polymer component has a melting point or softening point lower than that of the protective polymer component by 20 ° C. or more, preferably 30 ° C. or more. This polymer is preferably a crystalline fiber-forming polymer from the viewpoint of the fiberization process, but an amorphous polymer may be used for the purpose of the present invention.

  Further, the conjugate fiber of the present invention can be used for a wide variety of applications either alone or in combination with other fibers. When mixed with other fibers, mixed fibers, plying, ply twisting, weaving, knitting, and any other means can be used, and the obtained fabric is subjected to various post-processing if necessary. Can be used for various applications. Preferable applications of the conjugate fiber of the present invention include gill nets, trawl nets, trawl nets, and construction nets that make the most of the characteristics of a polyester fiber having an unprecedented high specific gravity and practically strong fiber strength. It is most suitable for various fishing net applications such as nets. Particularly, it is most suitable for fixed nets of salmon, yellowtail, tuna, horse mackerel, mackerel, sardine, sea bass, squid and others.

  In addition to fishing net applications, it can be applied to various industrial material applications, such as polyester fibers with high specific gravity performance, such as those used for silt protectors used in civil engineering works. In addition to industrial materials, applications to non-clothing fields such as curtains and blackout curtains are also suitable.

  The present invention has an unprecedented high fiber strength and high specific gravity performance by obtaining a composite fiber comprising two components of a core polymer component and a protective polymer component to which specific inorganic particles are highly added, and as a fiber for fixed netting. A composite fiber having no pollution problem and having a suitable hue can be provided.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In the present invention, [η], the average particle diameter of the fine particles, the fiber specific gravity, the strength, the elongation, and the number average molecular weight of nylon can be determined by the following methods.
Polyester [η]: Measured at a temperature of 30 ° C. using a mixed solvent of phenol and tetrachloroethane 1: 1 as a solvent.
-Number average molecular weight of nylon: Measured by GPC chromatogram using HLC-510 manufactured by Waters.
Average particle diameter of fine particles: Measured by a centrifugal automatic particle size distribution analyzer, CAPA-500, manufactured by Horiba, Ltd.
Fiber specific gravity: A density gradient was created using carbon tetrachloride and normal hexane as a solvent, and measured at 20 ° C.
-Fiber strength and elongation: Measured at 20 ° C and 65 RH% using a tensile tester (Autograph IM-100) manufactured by Shimadzu Corporation.

Example 1
Nylon 6 powder having a number average molecular weight of 11,000 (trade name: P1011F) manufactured by Ube Industries, Ltd. was used as a base polymer of a core polymer component, and spherical magnetite powder having an average particle diameter of 0.2 μm with respect to the polymer powder. 30% by weight (manufactured by Toda Kogyo Co., Ltd .: surface ferrite coated product, specific gravity 5.0) and 40% by weight of titanium dioxide (specific gravity 4.2, manufactured by Titanium Industry Co., Ltd.) having an average particle diameter of 0.35 μm. And the mixture was melt-kneaded with a twin-screw kneader and extruded into strands. The strands were cut into pellets, and dried at 90 ° C. under vacuum to a water content of 180 ppm. On the other hand, as the protective polymer component, polyethylene terephthalate containing 0.08% by weight of titanium dioxide and having an intrinsic viscosity [η] of 0.80 was melt-polymerized by a conventional method and pelletized.

  The obtained protective polymer component and core polymer component are melt-extruded by separate extruders, and are joined at a nozzle portion at a spinning temperature of 295 ° C. so that the protective polymer component becomes a sheath, and a composite weight ratio (protective polymer component): ( (Core polymer component) = 2: 1, the cross section was made into a core-sheath shape as shown in FIG. 1 (1), discharged by an 8-hole nozzle with a nozzle diameter of 0.4 mmφ, and wound at a spinning speed of 1000 m / min. At this time, the polyethylene terephthalate forming the protective polymer component after the fiber formation was [η] 0.75.

  The obtained spun yarn is stretched at a draw ratio of 4.0 times on a hot roller at 80 ° C. and a hot plate at 140 ° C., and then heat-treated at 180 ° C. with a 3% overfeed. The multifilament was wound up. When the cross-sectional shape of this multifilament yarn was observed with a microscope, the core-sheath ratio was almost constant in any fiber and also in the length direction, and the core component was completely covered by the sheath component. Excellent homogeneity and no fluff. Further, no trouble was observed in the spinning step and the drawing step. The resulting fiber had a specific gravity of 1.58, a strength of 4.5 g / dr and an elongation of 15%.

  A net was prepared by combining the obtained drawn yarns and subjected to a test in the sea. The sedimentation was good, the net shaking in the sea was small, the durability was excellent, and the fiber was suitable as a fishing net. Was confirmed.

  It was found that the specific gravity of the obtained fiber was different by changing the heat treatment temperature during drawing. As a result of drawing under the following conditions from the spinning conditions collected under the same conditions as described above, fibers having the following physical properties were obtained.

Elongation temperature conditions Fiber properties
HR ₁ HP HR ₂ p DT DE Fluff [1] 80 ° C 140 ° C 180 ° C 1.58 4.5g / d 15 ○
[2] 〃 １６０ 160 1.53 4.3 13 ○
[3] 〃 ２３０ 230 1.60 4.7 10 ×
Note: HR ₁ = hot roller (first roller), HP = hot plate, HR ₂ = hot roller (second roller), p = specific gravity, DT = strength, DE = elongation

  It was found that the higher the heat treatment temperature during the shrinkage treatment, the better the fiber properties were. However, an extremely high heat treatment temperature is not preferable because stretching fuzz occurs frequently.

  The fiberization was carried out in exactly the same manner as above except that the magnetite fine particles were replaced with those described above, and the specific gravity was 5.0, manufactured by Toda Kogyo KK without surface coating. As a result, the specific gravity of the fiber was 1.53, which was slightly lower than that of the surface-coated product.

Example 2
Except for adding 0.2% by weight of copper iodide to the core polymer component, a conjugate fiber was produced in the same manner as in Example 1, and the strength retention of the obtained fiber was examined. As evaluation means, the strength retention after irradiation with carbon fade at 400C for 83 hours at 83 ° C and the strength retention after irradiation for 400 hours with xenon weather at 83 ° C were examined. As a result, after 400 hours of carbon fade, the average strength retention at n = 5 was about 86%, and after 400 hours of xenon weather, the average strength retention at n = 5 was about 84%. On the other hand, the fiber obtained in Example 1 had a strength retention of about 42% after 400 hours of carbon fade, and a strength retention of about 36% after 400 hours of xenon weather.

Examples 3 to 8
Example 3 is 50% by weight of magnetite and 20% by weight of titanium dioxide in the core polymer component, Example 4 is 70% by weight of 20% by weight of magnetite and 50% by weight of titanium dioxide, and Example 5 is magnetite. A composite fiber was obtained in the same manner as in Example 2 except that the total was 70% by weight of 10% by weight and 60% by weight of titanium dioxide. In each case, there was no trouble in processability, and fibers having good fiber properties were obtained. In Example 4, the hue of the obtained fiber was gray and slightly different from black, and in Example 5, the hue of the fiber was whitish gray. In Example 6, the content of the fine particles in the core polymer component was 30% by weight of magnetite and 20% by weight of titanium dioxide, so that the total was 50% by weight. In Example 7, the [η] of the protective polymer component was 0.85. 8 was carried out in the same manner as in Example 2 except that the composite ratio of the protective polymer component and the core polymer component was 1: 1. In each case, the processability was good, and fibers with high specific gravity and high strength were obtained. Table 1 summarizes the [η] of the protective polymer component in these examples, the type and blending ratio of the fine particles in the core polymer component, the composite ratio of the protective polymer component and the core polymer component, and the cross-sectional shape of the fiber. Table 2 shows the evaluation of the processability and physical properties of these fibers.

Examples 9 to 10
Example 9 used zinc oxide (specific gravity 5.5) having an average particle size of 1.0 μ instead of titanium dioxide, and Example 10 used alumina (specific gravity 3.98) having an average particle size of 2.0 μ. Except for the above, a composite fiber was obtained in the same manner as in Example 2. In all cases, except that slight fluff was generated during spinning, good processability and good fibers were obtained (see Tables 1 and 2).

Examples 11 to 12
In Example 11, composite spinning was performed in the same manner as in Example 2 except that the cross-sectional shape was changed to FIG. 1 (2), and in Example 12, the cross-sectional shape was changed to FIG. 1 (3). In each case, good processability and good fibers were obtained (see Tables 1 and 2).

Example 13
Except that nylon 12 (3014U manufactured by Ube Industries, Ltd.) was used as the base polymer of the core polymer component, a conjugate fiber was produced in the same manner as in Example 3, but the processability was good and a good fiber was obtained. Was obtained (see Tables 1 and 2).

Example 14
A composite fiber was obtained in the same manner as in Example 2, except that nylon 6 having a number average molecular weight of 22,000 (trade name: P1022 manufactured by Ube Industries, Ltd.) was used as the core polymer component. Tables 1 and 2).

Comparative Example 1
A polyethylene terephthalate chip having [η] of 0.65 before spinning was used as a protective polymer component, and spinning was performed so that [η] after spinning became 0.60, in the same manner as in Example 2. A composite fiber was obtained. As a result, fluff was slightly generated during spinning and stretching, and the fiber strength was as low as 2.5 g / d due to the low viscosity of the protective polymer component, which was inferior to Example 2.

Comparative Example 2
A composite fiber was obtained in the same manner as in Example 2, except that the total of 30% by weight was 15% by weight of magnetite and 15% by weight of titanium dioxide as fine particles. Although the processability was good and fiberization was possible, the fiber specific gravity was 1.45, which was inferior to Example 2.

Comparative Examples 3 and 4
Comparative Example 3 used silicon dioxide particles having an average particle size of 0.1 μ and a specific gravity of 2.2 instead of titanium dioxide, and Comparative Example 4 used kaolin particles having an average particle size of 1.0 μ and a specific gravity of 2.5. Was carried out in the same manner as in Example 2. In each case, fluff was generated, and spinnability and stretchability were not so good. The specific gravity of the obtained fiber was also lower than that of Example 2.

Comparative Examples 5-6
Comparative Example 5 uses the same polymer as in Example 2, Comparative Example 5 has a composite ratio of the protective polymer component: the core polymer component of 85:15, and Comparative Example 6 has a composite ratio of the protective polymer component: the core polymer component of 15:85. Composite spinning was performed in the same manner as in No. 2. In Comparative Example 5, the fiberization was possible, but the fiber specific gravity performance was at a poor level. In Comparative Example 6, spinnability and stretchability were poor, and fluff and breakage occurred frequently, and a fiber whose performance could be evaluated was not obtained. Table 1 summarizes [η] of the protective polymer component in Comparative Examples 1 to 6, types of fine particles in the core polymer component and the compounding ratio thereof, the composite ratio of the protective polymer component and the core polymer component, and the cross-sectional shape of the fiber. The evaluation of the processability and physical properties of these fibers is as shown in Table 2.

Example 15
A nylon 6 powder having a number average molecular weight of 11,000 (trade name: P1011F) manufactured by Ube Industries, Ltd. is used as a base polymer of a core polymer component, and titanium dioxide (titanium) having an average particle diameter of 0.35 μm is used for the polymer powder. 70% by weight, specific gravity 4.2) manufactured by Kogyo Co., Ltd. are mixed, the mixture is melt-kneaded with a twin-screw kneader, extruded into strands, and the strands are cut into pellets. The rate was 460 ppm. On the other hand, as a protective polymer component, polyethylene terephthalate having an intrinsic viscosity [η] of 0.80 containing 1.5% by weight of carbon black (manufactured by Degussa) having a primary average particle size of 0.03 μm is melt-polymerized by an ordinary method. And pelletized one. A composite fiber was obtained in the same manner as in Example 2 using both these polymers. [Η] of polyethylene terephthalate as a protective polymer component of the obtained conjugate fiber was 0.75. In addition, the fiber specific gravity was 1.57, the strength was 4.6 g / dr, and the elongation was 18%. The fiber had excellent performance for use in fishnets.

Example 16
A conjugate fiber was obtained in the same manner as in Example 15, except that the content of titanium dioxide was 55% by weight. The specific gravity of the obtained fiber was 1.53, the strength was 5.2 g / dr, and the elongation was 20%. A fiber excellent in both spinnability and stretchability was obtained.

Example 17
A composite fiber was obtained in the same manner as in Example 15, except that 50% by weight of titanium dioxide, an average particle size of 1.0 μm, and zinc oxide having a specific gravity of 5.5 and 20% by weight were contained in a total of 70% by weight. Was. The specific gravity of the obtained fiber was 1.58, the strength was 4.5 g / dr, and the elongation was 15%. Although some fluff occurred during spinning, it had excellent stretchability and excellent performance for fishing net use. The obtained fiber was obtained.

Example 18
A composite fiber was obtained in the same manner as in Example 15, except that 50% by weight of titanium dioxide, 2.0 μm in average particle diameter, and 20% by weight of alumina having a specific gravity of 3.9 were contained in a total of 70% by weight. . The specific gravity of the obtained fiber was 1.56, the strength was 4.5 g / dr, and the elongation was 15%. Although some fluff was generated during spinning, it had excellent stretchability and excellent performance for fishing net use. The obtained fiber was obtained.

Example 19
A composite fiber was obtained in the same manner as in Example 15 except that 50% by weight of titanium dioxide, an average particle diameter of 0.6 μm, and barium sulfate having a specific gravity of 4.3 were contained in a total of 70% by weight. Was. The specific gravity of the obtained fiber was 1.57, the strength was 4.5 g / dr, and the elongation was 14%. Although some fluff was generated during spinning, it had excellent stretchability and excellent performance for fishing net use. The obtained fiber was obtained. [Η] of the protective polymer component, the content of the colorant, the type and blending ratio of the fine particles in the core polymer component, the compounding ratio of the protective polymer component and the core polymer component, and the cross-sectional shape of the fibers in Examples 15 to 19 were summarized. The results are shown in Table 3, and the evaluations of processability and physical properties of these fibers are shown in Table 4.

Example 20
Nylon 6 (Ube Industries, Ltd.) having a number average molecular weight of 11,000 and containing 60% by weight of titanium dioxide (rutile type; specific gravity 4.2, manufactured by Titanium Industry Co., Ltd.) having an average particle diameter of 0.35 μm is a core polymer component. (Water content: 100 ppm), polyethylene terephthalate containing 0.08% by weight of titanium dioxide and having an intrinsic viscosity of [η] 0.95 as a protective polymer component was melt-extruded with a separate extruder, and a spinning temperature of 300 ° C. Then, the protective polymer component is joined at the nozzle portion so as to form a sheath, and the composite weight ratio (protective polymer component) :( core polymer component) = 1: 1, and the cross section is formed into a core-sheath shape as shown in FIG. Then, the liquid was ejected by a 200 hole nozzle having a nozzle diameter of 0.5 mmφ. The discharged yarn was passed through a heating zone of 20 cm length and 380 ° C. provided immediately below the nozzle, cooled at 25 ° C. with a cooling air flow of 7 Nm ³ per minute, applied a spinning oil agent with an oiling roller, and spun at a spinning speed of 600 m. / Min.

Subsequently, without once winding the yarn, stretching and heat treatment were carried out in the following manner and wound.
Stretching: After heating with a hot roll at 110 ° C., stretched 4.3 times in one step while injecting heated steam at 400 ° C.
Heat treatment: 3% shrinkage treatment between a hot roll at 220 ° C. and a relax roll.
As a result, the process stability was good, and a highly practical fiber having 1004 denier, strength of 4.0 g / d, elongation of 18%, and specific gravity of 1.62 was obtained.

Example 21
25% by weight of titanium dioxide (rutile type; specific gravity 4.2, manufactured by Titanium Industry Co., Ltd.) having an average particle size of 0.35 μm and α-type hematite powder having an average particle size of 0.2 μm (manufactured by Toda Kogyo Co., Ltd., specific gravity 5.2) ) Containing 50% by weight of nylon 6 having a number average molecular weight of 12,000 as a core polymer component (moisture content: 200 ppm), and containing 1.0% by weight of carbon black (manufactured by Degussa) and having an intrinsic viscosity of [η] 1. Polyethylene terephthalate, which is 0, is used as a protective polymer component, melt-extruded with a separate extruder, and joined at a nozzle at a spinning temperature of 300 ° C. so that the protective polymer component becomes a sheath, and a composite weight ratio (protective polymer component): ( (Core polymer component) = 2: 1, the cross-section was made into a core-sheath shape as shown in FIG. 1A, and the nozzle was discharged with a nozzle diameter of 0.6 mmφ and a 100-hole nozzle. The discharged yarn was passed through a heating zone of 20 cm length and 380 ° C. provided immediately below the nozzle, cooled at 25 ° C. with a cooling air flow of 7 Nm ³ per minute, applied a spinning oil agent with an oiling roller, and spun at a spinning speed of 600 m. / Min.

Subsequently, without once winding the yarn, stretching and heat treatment were carried out in the following manner and wound.
Stretching: After heating with a hot roll at 110 ° C., stretch one step to 4.8 times while injecting heated steam at 450 ° C.
Heat treatment: 4% shrinkage treatment between 210 ° C. hot roll and relaxation roll.
As a result, the process stability was good, and a highly practical fiber having 1002 denier, strength of 5.5 g / d, elongation of 19%, and specific gravity of 1.62 was obtained.

Comparative Example 7
Except for changing the temperature of the heated steam to 300 ° C., a conjugate fiber was produced in the same manner as in Example 20, but as a result, the strength was 3.3 g / dr, the elongation was 20%, and the specific gravity was a little 1.54. However, a fiber whose fiber strength did not reach the present invention was obtained. This is considered to be due to insufficient flow of the core polymer component at the time of drawing, and the yarn was frequently broken at the time of drawing.

Examples 22 to 23, Comparative Example 8
A conjugate fiber was manufactured in the same manner as in Example 20, except that the heat treatment temperature after drawing was 245 ° C (Example 22), 160 ° C (Example 23), and 256 ° C (Comparative Example 8). As a result, in the case of 245 ° C., a fiber having a strength of 4.2 g / dr, an elongation of 21%, a specific gravity of 1.63 and a high strength and a high specific gravity was obtained, but slight breakage was observed during the heat treatment. In the case of 160 ° C., the strength was 3.7 g / dr, the elongation was 15%, and the specific gravity was 1.53. At 256 ° C., the fibers were partially fused and broken.

Comparative Example 9
In Example 1, when the core component had a water content of 650 ppm, screws fell off from the nozzle holes and spinning was impossible at all.

FIGS. 1 (1) to 1 (8) are schematic diagrams showing typical composite forms of a core polymer component and a protective polymer component in the fiber cross section of the present invention.

Explanation of reference numerals

1: core polymer component 2: protective polymer component

Claims (9)

A core polymer component containing 50 to 85% by weight of fine particles of a lead-free metal or a compound thereof having a specific gravity of 3 or more, and a protective polymer component covering the core polymer component and having a coloring agent added thereto, A conjugate fiber having a fiber specific gravity of 1.5 or more and a strength of 3.5 g / d or more. The composite fiber according to claim 1, wherein the fine particles are iron oxide and titanium dioxide. The conjugate fiber according to claim 1, wherein the core polymer component is a polyamide having a number average molecular weight of 22,000 or less, and the protective polymer component is a polyester having an intrinsic viscosity of 0.7 or more. The conjugate fiber according to any one of claims 1 to 3, wherein the core polymer component contains 0.01% by weight or more of copper iodide. The conjugate fiber according to claim 1, wherein the colorant is carbon black. A thermoplastic polymer containing a total of 50 to 85% by weight of titanium dioxide and other inorganic fine particles having a specific gravity of 3 or more as a core component, having a melting point or softening point higher by at least 20 ° C. than the thermoplastic polymer, and coloring Composite spinning using a thermoplastic polymer containing an agent as a protective component, followed by heat drawing, and then at least (melting point or softening point -80) ° C of the thermoplastic polymer of the core component and (melting point or softening of the thermoplastic polymer component of the sheath component). Point -5) A method of producing a conjugate fiber having a fiber specific gravity of 1.5 or more and a strength of 3.5 g / d or more by performing a heat treatment at a temperature of not more than ℃. The method for producing a conjugate fiber according to claim 6, wherein the core polymer component is polyamide, and the water content of the core component containing inorganic fine particles is 500 ppm or less. The method according to claim 7, wherein the polyamide has a number average molecular weight of 22,000 or less. The method according to claim 6, wherein the colorant is carbon black.

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