JP5783046B2 - Synthetic fiber and method for producing the same - Google Patents

Description

  The present invention relates to a synthetic fiber comprising a polymer alloy containing an aliphatic polyester resin and a thermoplastic polyamide resin, and a method for producing the same.

  Recently, with increasing awareness of the environment on a global scale, the development of fiber materials that decompose in the natural environment is eagerly desired.

  For example, since conventional general-purpose plastics use petroleum resources as a main raw material, global warming caused by petroleum resources will be depleted in the future and mass consumption of petroleum resources are taken up as major problems. For this reason, in recent years, research and development on various plastics and fibers such as aliphatic polyester resins have been activated. Among them, attention is focused on plastics that are decomposed by microorganisms, that is, fibers using biodegradable plastics.

  Moreover, by using plant resources that take in carbon dioxide from the atmosphere and grow as raw materials, it can be expected that global warming can be suppressed by the circulation of carbon dioxide, and the problem of resource depletion may be solved. Therefore, attention has been focused on plastics starting from plant resources, that is, biodegradable plastics using biomass.

  Until now, biodegradable plastics using biomass have not been used as general-purpose plastics because they have low mechanical properties and heat resistance and high production costs. On the other hand, in recent years, polylactic acid using lactic acid obtained by fermentation of starch as a raw material has attracted attention as a biodegradable plastic having relatively high mechanical properties and heat resistance and low production cost.

  Aliphatic polyester resins typified by polylactic acid have been used for a long time in the medical field as, for example, surgical sutures, but recently, due to the improvement of mass production technology, it is possible to compete with other general-purpose plastics in terms of price. became. Therefore, as for the aliphatic polyester resin, product development as a fiber has been activated.

  Development of fibers made of aliphatic polyester resin is preceded by agricultural materials and civil engineering materials that utilize biodegradability. Subsequent large-scale applications are expected to be applied to apparel, interiors such as curtains and carpets, vehicle interiors, and industrial materials. However, when fibers made from aliphatic polyester resins are applied to clothing and industrial materials, the wear resistance and hydrolysis resistance of fibers made from aliphatic polyester resins, especially fibers made from polylactic acid, are low. It becomes a big problem.

  For example, when a fiber made of polylactic acid is used for clothing, color transfer easily occurs due to rubbing or the like, or in severe cases, the fiber becomes fibrillated and whitened, and practical durability is poor. I know. In addition, when fibers made of polylactic acid are used for automobile interiors, especially carpets that are subject to strong rubbing, the fibers made of polylactic acid easily fall down and scrape, and in severe cases a hole is opened. Sometimes. In addition, aliphatic polyester resins (especially polylactic acid) may be prone to hydrolysis, and fibrillation and abrasion as described above tend to become severe over time, and there is a problem that product life is short. I know.

  As a method for improving the abrasion resistance of a fiber made of polylactic acid, for example, a polylactic acid that suppresses wear by adding a lubricant such as fatty acid bisamide to the fiber made of polylactic acid to reduce the friction coefficient of the fiber surface. The fiber which consists of is proposed (refer patent documents 1-4).

  Moreover, the invention which improves the mechanical characteristics of a resin composition by the blend of a polyamide resin and an aliphatic polyester resin is proposed (refer patent document 5). According to this proposal, due to the reinforcing effect of the polyamide resin, the mechanical properties such as the strength, heat resistance and wear resistance of the aliphatic polyester resin are improved.

  Furthermore, by adding a compatibilizing agent containing two or more active hydrogen reactive groups in one molecule, the adhesion at the interface between the polyamide resin and the aliphatic polyester resin is strengthened and the interface peeling due to external force is suppressed. A fiber made of a polymer alloy has been proposed (see Patent Document 6).

JP 2004-91968 A (pages 4-5) JP 2004-204406 A (pages 4-5) JP 2004-204407 A (pages 4 to 5) JP-A-2004-277931 (pages 5-6) JP 2003-238775 A (page 3) JP 2006-233375 A (pages 1, 4 and 5)

  However, all of the proposed prior arts have problems. For example, as proposed in Patent Documents 1 to 4, with a single fiber made of polylactic acid, hydrolysis proceeds under high temperature and high humidity, resulting in a significant decrease in strength. . In the method proposed in Patent Document 5, since the aliphatic polyester resin and the polyamide resin are incompatible with each other, the adhesiveness at the interface between these two phases is inferior. It turned out that there was a problem that it was blurred and the wear rate was high. Further, even in the case of the proposal of Patent Document 6, peeling of the interface between the polyamide resin and the aliphatic polyester resin is not completely suppressed, and the friction resistance is greatly deteriorated as compared with the case of a single component of the polyamide resin. As a result, the application was also limited.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a synthetic fiber made of a polymer alloy containing an aliphatic polyester resin and a thermoplastic polyamide resin, which has excellent wear resistance and can provide a high-quality fiber structure. And a method of manufacturing the same.

The present invention achieves the above object, and the synthetic fiber of the polymer alloy of the present invention contains an aliphatic polyester resin (A), a thermoplastic polyamide resin (B), and a compatibilizing agent (C). A synthetic fiber, wherein the compatibilizer (C) is a linear styrene / (meth) acrylate copolymer having a glycidyl group.

  According to a preferred aspect of the synthetic fiber of the present invention, the aliphatic polyester resin (A) forms an island component, and the thermoplastic polyamide resin (B) forms a sea island structure synthetic fiber. .

  According to a preferred embodiment of the synthetic fiber of the present invention, the yarn unevenness (U%) of the synthetic fiber is 0.8% or less.

  According to a preferred aspect of the synthetic fiber of the present invention, the aliphatic polyester resin (A) is a crystalline resin and has a melting point of 150 to 230 ° C.

  According to a preferred aspect of the synthetic fiber of the present invention, the thermoplastic polyamide resin (B) is a crystalline resin and has a melting point of 150 to 250 ° C.

  According to the preferable aspect of the synthetic fiber of this invention, the blend ratio (mass ratio) of the said aliphatic polyester resin (A) and the said thermoplastic polyamide resin (B) is 5 / 95-55 / 45.

  According to a preferred aspect of the synthetic fiber of the present invention, the compatibilizing agent (A) with respect to the total amount of the aliphatic polyester resin (A), the thermoplastic polyamide resin (B) and the compatibilizing agent (C) ( The addition amount of C) is 0.005 to 5% by mass.

  The fiber structure of the present invention contains the synthetic fiber of the polymer alloy described above at least in part.

In addition, the method for producing a synthetic fiber of polymer alloy of the present invention includes an aliphatic polyester resin (A), a thermoplastic polyamide resin (B), and a linear styrene / (meth) acrylate ester copolymer having a glycidyl group. A compatibilizer (C) comprising the above is supplied to an extrusion kneader and melt-kneaded to produce a polymer alloy, and the polymer alloy is spun at a melting point Tmb + 10 ° C. to the same melting point Tmb + 40 ° C. of the thermoplastic polyamide resin (B). And spinning at a spinning speed of 500 to 5,000 m / min.

  According to a preferred embodiment of the method for producing a synthetic fiber of the present invention, the blend ratio (mass ratio) of the aliphatic polyester resin (A) and the thermoplastic polyamide resin (B) is 5/95 to 55/45. It is.

  According to a preferred embodiment of the synthetic fiber production method of the present invention, the compatibilization with respect to the total amount of the aliphatic polyester resin (A), the thermoplastic polyamide resin (B), and the compatibilizer (C). The amount of the agent (C) added is 0.005 to 5% by mass.

  ADVANTAGE OF THE INVENTION According to this invention, the synthetic fiber which consists of a polymer alloy containing an aliphatic polyester resin and a thermoplastic polyamide resin which can improve a wear resistance markedly and can give a high quality fiber structure is obtained.

  In addition, according to the present invention, a high-quality fiber structure made of the above-described polymer alloy synthetic fiber, which is remarkably excellent in wear resistance, can be obtained.

  As will be described later, the synthetic fiber of the polymer alloy of the present invention is most suitable for general clothing use, industrial material use, and the like, and its uses are diverse.

FIG. 1 is a schematic side view of a spinning device that is preferably used for producing a synthetic fiber made of the polymer alloy of the present invention.

  The polymer alloy synthetic fiber of the present invention is a synthetic fiber made of a polymer alloy obtained by blending an aliphatic polyester resin (A), a thermoplastic polyamide resin (B), and a compatibilizer (C).

  The aliphatic polyester resin (A) in the present invention (hereinafter sometimes referred to as “component A”) refers to a polymer in which aliphatic alkyl chains are linked by ester bonds. The aliphatic polyester resin (A) used in the present invention is preferably crystalline, and its melting point is preferably 150 to 230 ° C.

  Examples of the aliphatic polyester resin (A) used in the present invention include polylactic acid, polyhydroxybutyrate, polybutylene succinate, polyglycolic acid, and polycaprolactone. Among these, polylactic acid is most preferably used from the viewpoint of easy melt molding.

The above polylactic _{acid, - (O-CHCH 3 -CO} ) n - is a polymer having as a repeating unit, it is obtained by polymerizing lactic acid oligomers, such as lactic acid or lactide. Lactic acid has two optical isomers, D-form and L-form. In either L-form or D-form, the higher the optical purity, the higher the melting point, that is, the heat resistance is improved. Specifically, the polylactic acid preferably has an optical purity of 90% or higher. The melting point of polylactic acid is preferably 150 ° C. to 230 ° C., more preferably 170 ° C. to 230 ° C., in order to maintain the heat resistance of the fiber.

  Said melting | fusing point is temperature which gives the extreme value of the melting endothermic curve obtained by measuring using the differential scanning calorimeter DSC.

  However, apart from the system in which the polymers of the two optical isomers are simply mixed as described above, the two optical isomer polymers are blended and formed into a fiber, and then a high temperature of 140 ° C. or higher. When a stereocomplex in which racemic crystals are formed by heat treatment, the melting point can be increased to 220 to 230 ° C. In this case, “component A” refers to a mixture of poly (L lactic acid) and poly (D lactic acid), and the blend ratio (mass ratio) of both is preferably 40/60 to 60/40. When the blend ratio (mass ratio) of both is in this range, the ratio of the stereocomplex crystal can be further increased.

  In addition, residual lactide is present as a low molecular weight residue in polylactic acid. These low molecular weight residues are a cause of inducing dyeing abnormalities such as heating-heater stains in the stretching and false twisting process and dyed spots in the dyeing process. Residual lactide promotes hydrolysis of fibers and fiber molded articles, and decreases durability. Therefore, the amount of residual lactide in polylactic acid is preferably 0.3% by mass or less, more preferably 0.1% by mass or less, and further preferably 0.03% by mass or less.

  In addition, components other than lactic acid may be copolymerized within a range that does not impair the properties of polylactic acid. The components to be copolymerized include polyalkylene ether glycols such as polyethylene glycol, aliphatic polyesters such as polybutylene succinate and polyglycolic acid, aromatic polyesters such as polyethylene isophthalate, and hydroxycarboxylic acids, lactones, dicarboxylic acids and diols. An ester bond-forming monomer such as Among these, a polyalkylene ether glycol having good compatibility with the thermoplastic polyamide resin (B) (hereinafter sometimes referred to as “component B”) is preferably used. The copolymerization ratio of such copolymerization components may be in a range that does not impair the heat resistance reduction due to the melting point drop, and is preferably 0.1 to 10 mol% with respect to the lactic acid units constituting the polylactic acid.

  The molecular weight of polylactic acid is preferably high in order to increase the wear resistance, but if the molecular weight is too high, the moldability and stretchability in melt spinning tend to decrease. The weight average molecular weight of polylactic acid is preferably 80,000 or more, more preferably 100,000 or more, and further preferably 120,000 or more in order to maintain wear resistance. On the other hand, when the weight average molecular weight exceeds 350,000, the stretchability is lowered as described above. As a result, the molecular orientation is deteriorated and the fiber strength is lowered. Therefore, the weight average molecular weight is preferably 350,000 or less, more preferably 300,000 or less, and further preferably 250,000 or less.

  The weight average molecular weight is a value determined by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

  In the present invention, the method for producing polylactic acid preferably used as “component A” is not particularly limited.

  Specific examples of the method for producing polylactic acid include the method described in Japanese Patent Application Laid-Open No. 6-65360. That is, a direct dehydration condensation method in which lactic acid is dehydrated and condensed as it is in the presence of an organic solvent and a catalyst. Another method is described in Japanese Patent Laid-Open No. 7-173266. That is, it is a method of copolymerizing and transesterifying at least two types of homopolymers in the presence of a polymerization catalyst. Furthermore, the method described in US Pat. No. 2,703,316 may be mentioned. That is, an indirect polymerization method in which lactic acid is once dehydrated to form a cyclic dimer and then subjected to ring-opening polymerization.

  The thermoplastic polyamide resin (B) used in the present invention refers to a polymer having an amide bond. Examples of the thermoplastic polyamide resin (B) used in the present invention include polycapramide (nylon 6), polyundecanamide (nylon 11), polydodecanamide (nylon 12), and polyhexamethylene sebacamide (nylon). 610). Among these, in order to increase the compatibility with the component A, it is better that the methylene chain length of the polyamide is long, and in this respect, nylon 11, nylon 12 and nylon 610 are preferably used. The polyamide may be a homopolymer or a copolymer.

  In general, when the aliphatic polyester resin has a melting point, the melting point is usually 200 ° C. or lower, and thus the heat resistance is not high, and the physical properties tend to deteriorate rapidly when the melting point exceeds 250 ° C. It is in. Therefore, the thermoplastic polyamide resin (B) blended with the aliphatic polyester resin preferably has a melting point of 150 to 250 ° C, more preferably 230 ° C or less.

  On the other hand, considering the heat resistance of the fibers, the melting point of the thermoplastic polyamide resin (B) is preferably 150 ° C. or higher. The thermoplastic polyamide resin (B) may be a copolymer as described above, but is preferably crystalline because the wear resistance tends to decrease when the crystallinity decreases.

  The presence or absence of crystallinity of each of the aliphatic polyester resin (A) and the thermoplastic polyamide resin (B) used in the present invention can be determined by observing the melting peak in the differential scanning calorimeter (DSC) measurement. It can be judged that it is sex.

  In the present invention, the blend ratio (mixing ratio) of component A and component B is preferably a ratio that can achieve this because component A is preferably an island component and component B is a sea component, as will be described later. Is preferred. Specifically, in order to obtain a polymer alloy having a sea-island structure in which component A is an island component and component B is a sea component, the blend ratio (mass ratio) of component A / component B is 5/95 to 55/45. It is preferable to set it as the range.

  Further, when the ratio of component A is increased, the melt viscosity ηa of component A may be increased, and when the ratio of component B is increased, the melt viscosity ηb of component B may be increased. Moreover, since the blend ratio (mass ratio) of the component A and the component B becomes easier as the ratio of the component B is increased, it is more preferably 7/93 to 45/55, and further preferably 10/90 to 40. / 60, most preferably 15/85 to 30/70.

  Further, when the ratio of the melt viscosity of component A and component B (ηb / ηa) increases, the deformation of the component A constituting the island component in the nozzle hole increases, and the yarn called ballast generated in the spinning portion The swollen swell increases and the spinnability deteriorates. Therefore, the melt viscosity ratio (ηb / ηa) is preferably in the range of 0.1 to 2.0, more preferably 0.15 to 1.5, and still more preferably 0.2 to 1. 0.

The method for measuring the melt viscosity η is the melt viscosity when measured at a measurement temperature of 240 ° C. and a shear rate of 1216 sec ⁻¹ . Details of the method for measuring the melt viscosity η will be described later.

  When the cross section of the synthetic fiber of the polymer alloy of the present invention is observed with a transmission electron microscope (TEM) (40,000 times), it can be seen that a so-called sea-island structure is adopted. In the present invention, the blended state of component A and component B does not affect the wear resistance, but the domain size of component A constituting the island component is converted into a diameter (the domain is assumed to be a circle and converted from the area of the domain). The smaller the diameter, the higher the yarn strength. The domain size of component A is particularly preferably 0.6 μm or less in terms of diameter.

  The synthetic fiber of the present invention is a synthetic fiber composed of a polymer alloy containing an aliphatic polyester resin (A) and a thermoplastic polyamide resin (B). The synthetic fiber of the present invention preferably has a sea-island structure in which an aliphatic polyester resin forms an island component and a thermoplastic polyamide resin forms a sea component. Here, since the aliphatic polyester resin (A) and the thermoplastic polyamide resin (B) usually hardly react (ester-amide exchange hardly occurs), the above two polymers, that is, the aliphatic polyester resin (A). And the thermoplastic polyamide resin (B) are not so high as they are. Therefore, in the synthetic fiber of the present invention, in addition to the aliphatic polyester resin (A) and the thermoplastic polyamide resin (B), a specific compatibilizer (C) (hereinafter sometimes referred to as “component C” may be used). .) Is added to dramatically improve the interfacial adhesion, thereby improving the wear resistance.

  Component C used in the present invention is a styrene / (meth) acrylate copolymer having a glycidyl group. The “/” means copolymerization, and the same applies to the following description. By using a styrene / (meth) acrylate copolymer having a glycidyl group as component C, the interfacial adhesion between the aliphatic polyester resin (A) and the thermoplastic polyamide resin (B) is drastically improved. be able to.

  The styrene / (meth) acrylic acid ester copolymer having a glycidyl group is usually a copolymerizable vinyl monomer having styrene, (meth) acrylic acid ester and glycidyl group (preferably (meth) acrylic acid). It can be obtained by copolymerizing a comonomer such as glycidyl ester.

  Here, (meth) acrylic acid ester means methacrylic acid ester and / or acrylic acid ester.

  Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth ) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, neopentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, (meth) acrylic Lauryl acid, alkyl (meth) acrylate such as tridecyl (meth) acrylate and stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and tricyclodecynyl (meth) acrylate, etc. (Meth) acrylic acid alicyclic alkyl, (meth) acrylic acid 2- And heteroatom-containing (meth) acrylic acid esters such as toxiethyl, dimethylaminoethyl (meth) acrylate, chloroethyl (meth) acrylate, trifluoroethyl (meth) acrylate and tetrahydrofurfuryl (meth) acrylate. . These monomers can be used alone or in combination of two or more.

  Examples of the copolymerizable vinyl monomer having a glycidyl group include glycidyl (meth) acrylate, epoxycyclohexyl (meth) acrylate, epoxycyclohexanemethyl (meth) acrylate, allyl glycidyl ether and Examples thereof include vinyl glycidyl ether. Among these, glycidyl methacrylate, which is easily available and easily improves the adhesive strength, is preferably used.

  Among them, as the component C, a copolymer of polystyrene / butyl (meth) acrylate / glycidyl methacrylate or polystyrene / butyl (meth) acrylate / methyl (meth) acrylate / glycidyl methacrylate is preferable. As such a product (commercial product), “ARUFON” (registered trademark) manufactured by Toagosei Co., Ltd. is commercially available.

  By adding the styrene / (meth) acrylic ester copolymer having a glycidyl group of component C to component A and / or component B, melt blending and spinning, the compound of component C is converted into the component C Either component A reacts with either component B to form a cross-linked structure, or reacts only with either component A or component B, so that component C exists at the interface between both component A and component B By doing so, it is considered that interfacial peeling can be suppressed.

The glycidyl group has reactivity with the COOH end group, OH end group and NH ₂ end group present at the end of the polylactic acid resin or thermoplastic polyamide resin. In melt spinning, which is a method for producing a synthetic fiber according to the present invention, molding is performed at a relatively low temperature of 250 ° C. or lower, and thus a compound having a glycidyl group as described above is used in terms of excellent low-temperature reactivity.

  When the glycidyl group amount of the styrene / (meth) acrylic acid ester-based copolymer having a glycidyl group is 20 mgKOH / g or more, it can satisfy a preferable role as a compatibilizing agent. On the other hand, when it has a reactive group exceeding 200 mgKOH / g in one molecule, it tends to be excessively thickened during spinning and the spinnability tends to be lowered. Therefore, the amount of glycidyl group in one molecule is preferably 20 mgKOH / g or more and 200 mgKOH / g or less, more preferably 100 mgKOH / g or less, and further preferably 40 mgKOH / g or less. The amount of glycidyl group here is a theoretical value based on the polymerization raw material base used.

  In addition, a compound having a glycidyl group of 20 mgKOH / g or more and 200 mgKOH / g or less has excellent heat resistance and dispersibility during melt molding when it has a weight average molecular weight of 250 to 30,000. Therefore, it is preferably used. The weight average molecular weight of the compound having a glycidyl group of 20 mgKOH / g or more is more preferably 250 to 20,000.

The glycidyl group is known to be more reactive with the NH ₂ end group than the OH end group, and is excellent in reactivity with the thermoplastic polyamide resin (B). Furthermore, the acrylic polymer which is the main chain of the styrene / (meth) acrylic acid ester copolymer of the polymer having these reactive groups (glycidyl group) is an aliphatic polyester resin (A), particularly polylactic acid. These are excellent in compatibility, and are excellent in reactivity and dispersibility as a compatibilizer with both the thermoplastic polyamide resin (B) and polylactic acid.

  The reason why the styrene / (meth) acrylic acid ester-based copolymer having a glycidyl group used as component C in the present invention is not clear is not clear, but the copolymer of component C is the main polymer. It is a copolymer obtained by copolymerizing a glycidyl group-containing comonomer in the chain, and it is thought that the main chain is rich in reactivity because there is no long branch and no steric hindrance. Further, during the polymerization of this copolymer, it is considered that the heat resistance at high temperature is excellent because almost no auxiliary materials such as a chain transfer agent are used during the polymerization. For this reason, it is preferably used as a compatibilizing agent for a polymer alloy using polyamide that is spun at high temperature.

  Moreover, since the styrene / (meth) acrylic acid ester-based copolymer having a glycidyl group generally has a small molecular weight and composition distribution, it is considered to be rich in uniform reactivity at the time of melting.

  The amount of component C added can be appropriately determined according to the equivalent weight per unit mass of the reactive group of the compound to be used, the dispersibility and reactivity during melting, and the blend ratio (mass ratio) of component A and component B. The amount of component C added is preferably 0.005% by mass or more, more preferably 0.005% by mass or more with respect to the total amount (100% by mass) of component A, component B and component C in terms of inhibiting interfacial peeling. It is 02 mass% or more, More preferably, it is 0.1 mass% or more. If the amount of component C added is too small, the amount of diffusion and reaction at the interface between the two components of component A and component B will be small, and the effect of improving the interfacial adhesion will be limited. On the other hand, in order for the component C to exhibit performance without impairing the properties of the component A and the component B, which are the fiber base material, and the spinning property, the amount of the component C added may be 5% by mass or less. More preferably, it is 3 mass% or less, More preferably, it is 1.5 mass% or less.

  Further, in spinning, for the purpose of promoting the reaction of the compatibilizer (C), the reaction efficiency can be increased by adding a metal salt of a carboxylic acid, particularly a catalyst in which the metal is an alkali metal or an alkaline earth metal. . Among them, it is preferable to use a catalyst based on lactic acid such as sodium lactate, calcium lactate and magnesium lactate. In addition, a catalyst having a relatively large molecular weight such as a metal stearate may be used alone or in combination of two or more kinds for the purpose of preventing the heat resistance of the resin from being lowered due to the addition of the catalyst. As the addition amount of the catalyst, it is preferable to add 5 to 2000 ppm with respect to the synthetic fiber in order to control dispersibility and reactivity. The addition amount of the catalyst is more preferably 10 to 1000 ppm, and further preferably 20 to 500 ppm.

  Although the total fineness of the synthetic fiber of this invention can be set suitably by a use, it is preferable that it is 10-230 dtex.

  Although the single fiber fineness of the synthetic fiber of this invention can be suitably set with a use, Preferably it is 0.8-30 dtex.

  In order to keep the processability of the synthetic fiber and the mechanical strength of the product high, the strength of the synthetic fiber of the present invention is preferably 1.0 cN / dtex to 5.0 cN / dtex, more preferably 2 0.0 cN / dtex to 5.0 cN / dtex. Synthetic fibers having such strength can be produced by a melt spinning method and a drawing method described later.

  Moreover, it is preferable that the elongation of the synthetic fiber of this invention is 15 to 70% from a viewpoint that the process passability at the time of making a fiber product is favorable. Synthetic fibers having such elongation can be produced by a melt spinning method and a drawing method described later.

  Moreover, it is preferable that the boiling water shrinkage | contraction rate of the synthetic fiber of this invention is 0 to 20% from a viewpoint that the dimensional stability of a fiber and a fiber product is favorable.

  In addition, the conventional synthetic fiber of polymer alloy composed of an aliphatic polyester resin and a thermoplastic polyamide resin is likely to become thick and thin during the thinning deformation process in melt spinning, and there is a problem in quality such as yarn unevenness. However, in the synthetic fiber of the present invention, the two components of component A and component B are uniformly dispersed, and the fiber formation is excellent, so that the yarn unevenness is small. In the synthetic fiber of the present invention, the thread spot (Uster) (U% (Half)) is preferably 2.0% or less, more preferably 1 in order to suppress process passability and dyed spots after dyeing. 0.0% or less, more preferably 0.8% or less.

  The cross-sectional shape of the single fiber of the synthetic fiber of the present invention can be freely selected from a round cross-section, a hollow cross-section, a porous hollow cross-section, a multi-leaf cross section such as a trilobal cross section, a flat cross-section, a W cross-section, an X cross-section It is possible to select. The form of the synthetic fiber is not particularly limited, such as long fiber or short fiber. In the case of long fiber, it may be multifilament or monofilament.

  Moreover, when using the synthetic fiber of this invention as a fiber structure, it can apply to fiber structures, such as a woven fabric, a knitted fabric, a nonwoven fabric, a pile, and cotton. Moreover, these fiber structures may contain other fibers in addition to the synthetic fiber of the present invention. For example, it may be an aligned yarn, a twisted yarn, and a mixed yarn of the synthetic fiber of the present invention and natural fiber, regenerated fiber, semi-synthetic fiber and synthetic fiber. Other fibers include natural fibers such as cotton, hemp, wool and silk, regenerated fibers such as rayon and cupra, semi-synthetic fibers such as acetate, polyesters such as nylon, polyethylene terephthalate and polybutylene terephthalate, polyacrylonitrile and poly Synthetic fibers such as vinyl chloride can be applied.

  In addition, the use of the fiber structure using the synthetic fiber of the present invention includes clothing that requires wear resistance, for example, sports such as outdoor wear, golf wear, athletic wear, ski wear, snowboard wear, and pants thereof. There are women's and men's outerwear such as clothing, casual clothing such as blousons, coats, winter clothes and rainwear.

  Also, applications that require excellent durability and moisture aging characteristics over long periods of use include uniforms, comforters, mattresses, skin comforters, kotatsu comforters, cushions, baby comforters and blankets, pillows, cushions, etc. Use for bedding materials such as side covers, covers, mattresses, bed pads, hospital, medical, hotel and baby sheets, and sleeping bags, cradle and stroller covers, etc. be able to.

  Moreover, the fiber structure containing the synthetic fiber of the present invention can also be used for inner wear. Here, the inner wear is a generic term for lingerie such as T-shirt, slip, nightgown, shorts, camisole, chemise, petticoat and panty, and foundation such as bra, girdle and corset.

  Similarly, the fabric as the fiber structure of the present invention can be used as a place close to the skin, for example, in stockings. Here, the stocking refers to leg-related products such as pantyhose, long stockings, and stockings products and tights represented by short stockings. Leg parts and panty parts are particularly preferably used as stockings in stockings, and so-called Zokki knitting composed only of double covering yarn according to the present invention, or knitting using processed yarn or raw yarn as knitting yarn Any of them may be used.

  Next, although the manufacturing method of the synthetic fiber of this invention is demonstrated, the manufacturing method of this invention is not specifically limited to these.

  That is, an aliphatic polyester resin (component A) such as poly-L-lactic acid and a thermoplastic polyamide resin (component B) such as nylon 6 and a styrene / (meth) acrylate ester copolymer having a glycidyl group having a glycidyl group. A certain compatibilizing agent (component C) is kneaded using an extrusion kneader at a temperature of 230 to 240 ° C. while weighing separately to produce a polymer alloy. As the extrusion kneader, a biaxial extrusion kneader is preferably used from the viewpoint of the reaction time of the compatibilizer.

  The polymer alloy used in the present invention further includes additives such as particles, crystal nucleating agents, flame retardants, plasticizers, antistatic agents, antioxidants and ultraviolet absorbers as modifiers, and Patent Document 3. A lubricant may be included.

  In the present invention, the blending method of component A, component B and component C is a method of premixing three components of component A, component B and component C, or component A, component B or component A and component B, respectively. In addition, component C may be blended in advance, but a method in which the three components of component A, component B and component C are supplied to the extrusion kneader as described above and melt-kneaded is preferred.

  Furthermore, a polymer blend of an aliphatic polyester resin and a thermoplastic polyamide resin is a blend of incompatible polymers, and the melt exhibits a strong behavior with an elastic term. For this reason, when discharged from a die often seen in spinning of an alloy polymer, ballast (a phenomenon in which the polymer flow swells) may occur with a delay (away from the die surface). As a result, the ballast itself fluctuates, and the thinning behavior tends to become unstable due to the thinning starting from the ballast. In extreme cases, the yarn production itself may be difficult.

  Methods for suppressing this include increasing the spinning temperature to lower the elongational viscosity, increasing the discharge hole diameter of the spinneret to decrease the discharge linear velocity (polymer flow velocity at the final throttle portion of the discharge hole), A method of increasing L / D, which is a ratio of the length to the hole diameter, a method of rapidly cooling the discharged yarn, and the like are effective.

  The spinning temperature can be determined by the melting point of the thermoplastic polyamide resin of Component B. The optimum temperature range is Component B melting point Tmb + 10 ° C. to melting point Tmb + 40 ° C. For example, when the melting point Tmb of the component B is 200 ° C., it is 210 to 240 ° C.

  Moreover, the discharge linear velocity for suppressing the swelling by the ball of the said discharge yarn, and stabilizing a thinning and a deformation | transformation becomes like this. Preferably it is 1-50 m / min, More preferably, it is 6-40 m / min. More preferably, it is 10-30 m / min.

  Moreover, L / D becomes like this. Preferably it is 0.6-10, More preferably, it is 0.8-7, More preferably, it is 1-5.

  The cooling start position is preferably 0.01 to 0.2 m from the base surface, more preferably 0.015 to 0.15 m, and still more preferably 0.02 to 0.1 m. is there.

  The optimum value of the spinning speed varies depending on the ratio of the melt viscosity of component A and component B and the blend ratio of both components, but is preferably about 500 to 5,000 m / min.

  In addition, the synthetic fiber of the present invention is likely to undergo orientation relaxation when left in an unstretched fiber state, and if there is a time difference until stretching between unstretched packages, the fiber's strong elongation characteristics and heat shrinkage characteristics can be easily achieved. It tends to vary. Therefore, in the present invention, it is preferable to employ a direct spinning drawing method in which spinning and drawing are performed in one step. At that time, the draw ratio is preferably 1.0 to 4.0 times in consideration of generation of fluff due to drawing. The stretching temperature and heat setting temperature can be determined by the glass transition points and melting points of Component A and Component B. The stretching temperature is preferably 20 to 80 ° C, and the heat setting temperature is preferably Tmb-20 ° C to Tmb-150 ° C, and the stretching can be carried out.

  Next, the synthetic fiber of the polymer alloy of this invention is demonstrated in detail using an Example. The following methods were used for the measurement methods in the examples.

A. Relative viscosity of thermoplastic polyamide resin The relative viscosity of nylon 6 was measured by the following measurement method.
(A) A sample is weighed and dissolved in 98% by mass concentrated sulfuric acid so that the sample concentration becomes 1 g / 100 ml.
(B) The solution of item (a) is measured for the number of seconds (T1) dropped at 25 ° C. using an Ostwald viscometer.
(C) The falling seconds (T2) at 25 ° C. of 98 mass% concentrated sulfuric acid in which the sample is not dissolved are measured in the same manner as in the item (b).
(D) The 98% sulfuric acid relative viscosity (ηr) of the sample is calculated by the following equation. The measurement temperature is 25 ° C.
(Ηr) = (T1 / T2).

B. Melting point of polymer (a) Melting point measurement method of polylactic acid Using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer, using 20 mg of sample polymer, 20 ° C. to 200 at a temperature rising rate of 20 ° C./min. The temperature was raised to 200 ° C. and held at a temperature of 200 ° C. for 5 minutes, then the temperature was lowered from 200 ° C. to 20 ° C. at a temperature drop rate of −20 ° C./minute, held at a temperature of 20 ° C. for 1 minute, and further increased as 2ndRUN. The temperature of the endothermic peak observed when the temperature was raised from 20 ° C. to 200 ° C. at a temperature rate of 20 ° C./min was taken as the melting point.

(B) Method for measuring the melting point of polyamide Using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer, using 20 mg of sample polymer, the temperature was increased from 20 ° C. to 270 ° C. at a temperature increase rate of 20 ° C./min. After maintaining at a temperature of 270 ° C. for 5 minutes, the temperature was decreased from 270 ° C. to 20 ° C. at a temperature decrease rate of −20 ° C./min, held at a temperature of 20 ° C. for 1 minute, and then further increased to 2ndRUN as a temperature increase rate of 20 ° C. The temperature of the endothermic peak observed when the temperature was increased from 20 ° C. to 270 ° C. per minute was taken as the melting point.

C. Weight average molecular weight of polylactic acid (Mw)
Tetrahydrofuran was mixed with a chloroform solution of polylactic acid to obtain a measurement solution. This was measured by gel permeation chromatography (GPC), and the weight average molecular weight (Mw) was determined in terms of polystyrene.

D. Melt viscosity η
Using the Capillograph 1B manufactured by Toyo Seiki Co., Ltd., the melt viscosity of each of the aliphatic polyester resin and the thermoplastic polyamide resin was measured at a temperature of 240 ° C. and a shear rate of 1216 sec ⁻¹ in a nitrogen atmosphere. The measurement was performed three times, and the average value was taken as the melt viscosity.

E. Residual lactide amount of polylactic acid 1 g of a sample (polylactic acid polymer) was dissolved in 20 m of dichloromethane, and 5 ml of acetone was added to this solution. Further, the solution was fixed with cyclohexane and precipitated, analyzed by liquid chromatography using GC17A manufactured by Shimadzu Corporation, and the lactide amount was determined by an absolute calibration curve.

F. Size of island domain in synthetic fiber An ultrathin section was cut in the direction perpendicular to the fiber axis of the synthetic fiber of polymer alloy. The polyamide component of the ultrathin slice was metal-stained with phosphotungstic acid, and the blend state was observed and photographed using a 40,000 times transmission electron microscope (TEM). Using the image analysis software “WinROOF” of Mitani Shoji Co., Ltd., this photographed image is assumed to be a circle as the size of the island domain (non-stained part), and the diameter (diameter conversion) converted from the area of the domain ( 2r) was defined as the domain size. The number of domains to be measured was 100 per sample, and the distribution was defined as the domain size of island components (island domain size).
-TEM equipment: Hitachi H-7100FA type-Conditions: acceleration voltage 100kV
G. Strength and elongation of synthetic fiber A sample (synthetic fiber of polymer alloy) is a constant speed shown in JIS L1013 (chemical fiber filament yarn test method, 1998) by Tensilon UCT-100 manufactured by Orientec Co., Ltd. Measured under elongation conditions. The elongation at break was determined from the elongation at the point showing the maximum strength in the SS curve. The measurement was performed 10 times, and the average values were taken as strength and elongation.

H. Boiling water shrinkage (boiling yield) of synthetic fibers
A sample (synthetic fiber of polymer alloy) was immersed in boiling water for 15 minutes, and the boiling water shrinkage was determined by the following equation from the dimensional change before and after immersion. The measurement was performed three times, and the average value was defined as the boiling water shrinkage.
Boiling water shrinkage (%) = [(L0−L1) / L0] × 100
L0: A skein length measured by scraping a sample and measuring it under an initial load of 0.088 cN / dtex.
L1: A skein length measured under an initial load of 0.088 cN / dtex after treatment with boiling water in a load-free state and air drying.

I. Synthetic fiber thread spots U%
Using synthetic fiber (synthetic fiber of polymer alloy) as a sample, U% (Half) was measured at a yarn speed of 200 m / min and a measurement time of 5 minutes using UT4-CX / M manufactured by Zellwegerester. This was repeated 5 times, and the number average value thereof was defined as U% of the sample.

J. et al. Wear resistance evaluation (frosting evaluation, presence or absence of fibrillation)
After setting the test pieces on the top and bottom of the appearance / retention type tester described in JISL1076 (2006) and wearing them for 10 minutes with a pressure of 7.36 N (750 g), the degree of color fading was set to 1 to 5 (9 In addition, the presence or absence of fibrillation was evaluated using a magnifying glass.

  “No change” is “◎”, “Slightly fibrillated” is “◯”, “Clear fibrillated” is “△”, “Partial fiber collapse” is “×”, ◎ and ○ Was passed.

K. Spinning property As an evaluation of spinning property, when spinning 100 kg, “Good without thread breakage” is “◎”, “Thread breakage occurs once or twice” is “O”, and “Thread breakage occurs 3 to 5 times”. Is “△”, “thread breakage” is “×”, and ◎, ○, and Δ are acceptable.

Example 1
As component A, polylactic acid (melting point: 177 ° C.) consisting of L lactic acid having a weight average molecular weight of 220,000 and an optical purity of 98% is used, and as component B, nylon 6 (melting point: 225 ° C.) having a relative viscosity of sulfuric acid of 2.15 is used. Further, as Component C, a styrene / (meth) acrylate copolymer having a glycidyl group (manufactured by Toagosei Co., Ltd .: “ARUFON” (registered trademark) UG-4070, glycidyl group amount: 39 mgKOH / g, weight average molecular weight: 9700). Each component was dried separately to adjust the moisture content to 50 ppm, the blend ratio (mass ratio) was component A / component B = 30/70, and chip blending was performed with component C being 1.5 mass%. The amount of component C added is a concentration relative to the total amount (100% by mass) of component A, component B and component C.

The blended chip thus obtained is charged into a spinning hopper 1 of a spinning device equipped with a twin screw extrusion kneader shown in FIG. 1, and is led to the twin screw extrusion kneader 2 to be melt kneaded and polymer alloy (molten polymer). It was. The molten polymer was weighed and discharged by the spinning block 3, the molten polymer was guided to the built-in spinning pack 4, and the molten polymer was spun from the spinneret 5. At this time, the monomer suction device 6 was installed at a position 10 cm below the spinneret, and the yarn 8 was cooled and solidified by the uniflow cooling device 7 while removing the sublimated monomers and oligomers, and the oil supply device 9 supplied oil. Further, after being taken up by the first take-up roll 10, it is taken up by the winder 12 through the second take-up roll 11, and the drawn yarn which is a multifilament take-up yarn (cheese package) 13 having a total fineness of 88 dtex and 24 filaments. Got. About 100 kg of spinning was sampled, but no breakage or single yarn flow occurred, and the spinning was extremely stable. The melt spinning conditions are as follows. The discharge linear velocity in the die hole under the following conditions is 28.4 m / min, L / D in terms of round hole is 2.7, and the cooling start position is 0.1 m below the die surface.
-Kneader temperature: 225 ° C
-Spinning temperature: 245 ° C
Filter layer: 100 # Morundum sand filling Filter: 15 μm non-woven filter Filter base: Round hole with a diameter of 0.25 mm and a hole depth of 0.675 mm Discharge amount: 68.2 g / min (1 pack 2 yarns, 24 filaments )
・ Cooling: Uniflow is used. Cooling air temperature: 18 ° C., wind speed: 0.4 m / sec. / Oil agent: 10% by weight of fatty acid ester emulsion oil agent attached to yarn, spinning speed: 4000 m / min.

  When the cross section of the obtained synthetic fiber was observed with a TEM, it was found to have a uniformly dispersed sea-island structure, and the island domain size was 0.2 to 0.3 μm in terms of diameter. In addition, when a section having a cross section of the synthetic fiber was observed by alkali etching and dissolving and removing polylactic acid, it was confirmed that the island component was missing and the polylactic acid formed the island component. . Moreover, the strength of the obtained synthetic fiber was 2.2 cN / dtex, the elongation was 65%, and the yarn unevenness U% was 0.5%, all showing good fiber properties. Furthermore, the abrasion resistance performance of the obtained multifilament by the frosting test was 4-5 grade, and showed good abrasion resistance without fibrillation during the test.

(Example 2)
The same as Example 1 except that the blend ratio (mass ratio) of component A / component B was 7/93 and the ratio of component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) was 1.5 mass%. A multifilament was obtained. As in Example 1, the spinning of Example 2 was extremely stable with no yarn breakage or single yarn flow. When the TEM observation of the cross section of the obtained synthetic fiber was performed, it had a uniformly dispersed sea-island structure, and the island domain size was 0.01 to 0.15 μm in terms of diameter, which is an island component than in Example 1. The dispersion diameter of was small.

  Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was as good as 0.6%. The resulting multifilament had a wear resistance of 4-5 grade according to the frosting test, and exhibited good wear resistance without fibrillation during the test.

(Example 3)
Same as Example 1 except that the blend ratio (mass ratio) of component A / component B was 50/50 and the ratio of component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) was 1.5 mass%. A multifilament was obtained. In the spinning of Example 3, two yarn breaks occurred during sampling. Accordingly, when the appearance of the spinning portion was observed, the bulge of the yarn called ballast had a diameter about twice that of Example 1. When the TEM observation of the cross section of the obtained synthetic fiber was performed, a co-continuous structure in which the island domain size was slightly non-uniform as 0.3 to 1.5 μm in terms of diameter and the islands were partially bonded was observed. . Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was 0.7%, which was inferior to that of Example 1, but was at a level causing no problem in use. The resulting multifilament had a wear resistance performance of 4th grade by the frosting test, which was inferior to that of Example 1 and showed slight abrasion, but showed good wear resistance.

Example 4
Example 1 except that the blend ratio (mass ratio) of component A / component B is 30/70 and the ratio of component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) is 0.1 mass%. A multifilament was obtained. In the spinning of Example 4, two yarn breaks occurred during sampling. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.01 to 0.3 μm in terms of diameter, and the dispersion diameter of the island component was smaller than that of Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was 0.7%, which was inferior to that of Example 1, but was at a level causing no problem in use. The wear resistance performance of the obtained multifilament according to the frosting test was grade 3-4, which was inferior to that of Example 1 and slight fibrillation was observed, but it was at a level where it could be used without problems.

(Example 5)
The same as Example 1 except that the blend ratio (mass ratio) of component A / component B was 30/70, and the ratio of component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) was 3.0 mass%. A multifilament was obtained. As in Example 1, the spinning of Example 5 was extremely stable with no yarn breakage or single yarn flow. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.3 to 0.5 μm in terms of diameter, and the dispersion diameter of the island component was larger than that of Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was as good as 0.5%. The resulting multifilament had a wear resistance of grade 5 according to the frosting test, and exhibited good wear resistance without fibrillation during the test.

(Example 6)
Example 1 except that the blend ratio (mass ratio) of component A / component B is 30/70 and the ratio of component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) is 5.0 mass%. A multifilament was obtained. In the spinning of Example 6, two yarn breaks occurred during sampling. Further, an increase in pack pressure due to an increase in melt viscosity was confirmed. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was large and exceeded 2 μm in terms of diameter. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. The yarn unevenness U% was as good as 0.5%. The multifilament obtained had a wear resistance of grade 5 according to the frosting test, and showed very good wear resistance without fibrillation during the test.

(Example 7)
The blend ratio (mass ratio) of component A / component B is 30/70, and the ratio of component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4040, glycidyl group amount: 118 mgKOH / g, weight average molecular weight: 9200) is 3. A multifilament was obtained in the same manner as in Example 1 except that the content was 0% by mass. In the spinning of Example 7, two yarn breaks occurred during sampling. Further, an increase in pack pressure due to an increase in melt viscosity was confirmed. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.4 to 0.6 μm in terms of diameter, and the dispersion diameter of the island component was larger than that of Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. The yarn unevenness U% was as good as 0.6%. The resulting multifilament had a wear resistance performance of 4-5 grade according to the frosting test, and showed very good wear resistance without fibrillation during the test.

  The results of Examples 1 to 7 are shown together in Table 1.

(Example 8)
Component B is Nylon 6 (melting point 225 ° C.) with sulfuric acid relative viscosity 2.63, blend ratio (mass ratio) of component A / component B is 30/70, and component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) A multifilament was obtained in the same manner as in Example 1 except that the ratio was 1.5% by mass. In the spinning of Example 8, one yarn breakage occurred during sampling. When the appearance of the spinning part was observed, the bulge of the yarn called ballast had a diameter about 1.3 times that of Example 1. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.05 to 0.6 μm in terms of diameter, and the dispersion diameter of the island component was larger and the variation was larger than in Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was as good as 0.7%. The resulting multifilament had a wear resistance performance of 4th grade by a frosting test, and exhibited good wear resistance without fibrillation during the test.

Example 9
Component B is nylon 6 (melting point 222 ° C.) having a relative viscosity of 2.05 sulfuric acid, and component A / component B blend ratio (mass ratio) is 30/70, and component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) A multifilament was obtained in the same manner as in Example 1 except that the ratio was 1.5% by mass. As in Example 1, the spinning of Example 9 was extremely stable with no yarn breakage or single yarn flow. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.3 to 0.5 μm in terms of diameter, and the dispersion diameter of the island component was larger than that of Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was as good as 0.5%. The resulting multifilament had a wear resistance performance of 4-5 grade according to the frosting test, and exhibited good wear resistance without fibrillation during the test.

(Example 10)
Component A is polylactic acid having a weight average molecular weight of 150,000 (melting point: 170 ° C.), Component B is nylon 6 having a relative viscosity of sulfuric acid of 2.15 (melting point: 225 ° C.), and blend ratio (mass ratio) of component A / component B Was 30/70, and a multifilament was obtained in the same manner as in Example 1 except that the ratio of component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) was 0.1% by mass. In the spinning of Example 10, two yarn breaks occurred during sampling. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.01 to 0.2 μm in terms of diameter, and the dispersion diameter of the island component was smaller than that of Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was 0.7%, which was inferior to that of Example 1, but was a good value. The wear resistance performance of the obtained multifilament according to the frosting test was grade 3, which was inferior to that of Example 1 and fibrillation was observed, but it was at a level where it could be used without problems.

(Example 11)
Component A is polylactic acid having a weight average molecular weight of 150,000 (melting point: 170 ° C.), Component B is nylon 6 having a relative viscosity of sulfuric acid of 2.15 (melting point: 225 ° C.), and blend ratio (mass ratio) of component A / component B Was 30/70, and a multifilament was obtained in the same manner as in Example 1 except that the ratio of component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) was 1.5% by mass. As in Example 1, the spinning of Example 11 was extremely stable with no yarn breakage or single yarn flow. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.01 to 0.2 μm in terms of diameter, and the dispersion diameter of the island component was smaller than that of Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was 0.7%, which was inferior to that of Example 1, but was a good value. The wear resistance performance of the obtained multifilament according to the frosting test was grade 3-4, which was inferior to that of Example 1 and slight fibrillation was observed, but it was at a level where it could be used without problems.

(Example 12)
The same as Example 10 except that the blend ratio (mass ratio) of component A / component B was 30/70 and the ratio of component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) was 3.0 mass%. A multifilament was obtained. As in Example 1, the spinning of Example 12 was extremely stable with no yarn breakage or single yarn flow. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.01 to 0.2 μm in terms of diameter, and the dispersion diameter of the island component was smaller than that of Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was as good as 0.5%. The resulting multifilament had a wear resistance performance of 3 to 4 grades according to the frosting test, and fibrillation during the test was not confirmed, and it was a level that could be used without problems.

(Example 13)
Component B is nylon 6 (melting point 225 ° C.) having a relative viscosity of sulfuric acid of 2.90, blend ratio (mass ratio) of component A / component B is 30/70, and component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) A multifilament was obtained in the same manner as in Example 1 except that the ratio was 1.5% by mass. In the spinning of Example 13, five yarn breaks occurred during sampling.

  When the appearance of the spinning part was observed, the bulge of the yarn called ballast had a diameter about twice that of Example 1. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.4 to 0.6 μm in terms of diameter, and the dispersion diameter of the island component was larger than that of Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was as good as 0.7%. The wear resistance performance of the obtained multifilament according to the frosting test was grade 4, which was inferior to that of Example 1 and slight fibrillation was observed.

(Example 14)
Component B is nylon 610 (melting point 225 ° C.) having a relative viscosity of 2.20 sulfuric acid, blend ratio (mass ratio) of component A / component B is 30/70, and component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) A multifilament was obtained in the same manner as in Example 1 except that the ratio was 1.5% by mass. In the spinning of Example 14, as in Example 1, yarn breakage and single yarn flow did not occur, and the spinning was extremely stable. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.01 to 0.2 μm in terms of diameter, and the dispersion diameter of the island component was smaller than that of Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was as good as 0.5%. The resulting multifilament had a wear resistance performance of 4-5 grade according to the frosting test, and exhibited good wear resistance without fibrillation during the test.

(Example 15)
Component B is nylon 610 (melting point 225 ° C.) having a relative viscosity of 2.58 sulfuric acid, blend ratio (mass ratio) of component A / component B is 30/70, and component C (manufactured by Toagosei Co., Ltd .: ARUFON UG-4070) A multifilament was obtained in the same manner as in Example 1 except that the ratio was 1.5% by mass. In the spinning of Example 15, one yarn breakage occurred during sampling. When the appearance of the spinning part was observed, the bulge of the yarn called ballast had a diameter about 1.3 times that of Example 1. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.05 to 0.6 μm in terms of diameter, and the dispersion diameter of the island component was larger and the variation was larger than in Example 1. Moreover, when the section with a cross section of the synthetic fiber was alkali-etched to dissolve and remove polylactic acid, the island component was missing, and it was confirmed that polylactic acid formed the island component. Further, the yarn unevenness U% was as good as 0.7%. The resulting multifilament had a wear resistance performance of 4th grade by a frosting test, and exhibited good wear resistance without fibrillation during the test.

  The results of Examples 8 to 15 are collectively shown in Table 2.

(Comparative Example 1)
A multifilament was obtained in the same manner as in Example 1 except that the blend ratio (mass ratio) of component A / component B was 65/35 and component C was not added. In Comparative Example 1, yarn breakage occurred three times during sampling. When TEM observation of the cross section of the obtained synthetic fiber was performed, it took a relatively uniformly dispersed sea island structure, and the island domain size was 0.1 to 0.5 μm in terms of diameter. When the section having a cross-section of this was subjected to alkaline etching to dissolve and remove polylactic acid and observed, most of the sea component was missing, and it was confirmed that polylactic acid formed the sea component. Moreover, the yarn unevenness U% was as large as 2.0%, and the wear resistance performance of the obtained multifilament according to the frosting test was second grade, and partial disintegration of the fiber due to fibrillation was confirmed. Compared with Example 1, the operability, yarn unevenness U% and abrasion resistance were inferior, and the use was at a level that was considerably limited.

(Comparative Example 2)
The blend ratio (mass ratio) of component A / component B was 30/70, and component C (monoallyl diglycidyl isocyanuric acid (hereinafter referred to as MADGIC): Shikoku Kasei Co., Ltd.) was 1.0 mass%. A multifilament was obtained in the same manner as in Example 1 except that. In the spinning of Comparative Example 2, fluctuations in the pack pressure were confirmed, and yarn breakage occurred frequently. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.03 to 0.4 μm in terms of diameter. Further, the yarn unevenness U% was a little as high as 0.9%, and the wear resistance performance of the obtained multifilament according to the frosting test was second grade, and clear fibrillation was confirmed. Compared with Example 1, the operability, yarn unevenness U% and abrasion resistance were inferior, and the use was at a level that was considerably limited.

(Comparative Example 3)
The blend ratio (mass ratio) of component A / component B is set to 30/70, and component C (RESEDA: methyl methacrylate / glycidyl methacrylate copolymer (graft polymer), glycidyl group amount: 34 mgKOH / g) is set to 0.0. A multifilament was obtained in the same manner as in Example 1 except that the content was 1% by mass. In the spinning of Comparative Example 3, yarn breakage occurred twice during sampling. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.03 to 0.4 μm in terms of diameter. Further, the yarn unevenness U% was slightly large as 0.8%, and the wear resistance performance of the obtained multifilament according to the frosting test was 2-3 grade, and clear fibrillation was confirmed. Compared with Example 1, the operability, yarn unevenness U% and abrasion resistance were inferior, and the use was at a level that was considerably limited.

(Comparative Example 4)
The blend ratio (mass ratio) of component A / component B is 30/70, and the ratio of component C (RESEDA: methyl methacrylate / glycidyl methacrylate copolymer (graft polymer), glycidyl group amount: 34 mgKOH / g) A multifilament was obtained in the same manner as in Example 1 except that the content was 1.5% by mass. In the spinning of Comparative Example 4, the fluctuation of the pack pressure was confirmed during sampling, and yarn breakage occurred frequently. When the TEM observation of the cross section of the yarn was performed, the island domain size was 0.1 to 0.4 μm in terms of diameter. Moreover, the yarn unevenness U% was as large as 1.3%, and the wear resistance performance of the obtained multifilament according to the frosting test was grade 2-3, and clear fibrillation was confirmed. Compared with Example 1, the operability, yarn unevenness U% and abrasion resistance were inferior, and the use was at a level that was considerably limited.

(Comparative Example 5)
The same as Example 1 except that the blend ratio (mass ratio) of component A / component B was 30/70 and the ratio of component C (Nisshinbo: polycarbodiimide “LA-1”) was 1.0 mass%. A multifilament was obtained. In the spinning of Comparative Example 5, fluctuations in the pack pressure were confirmed, and yarn breakage occurred frequently. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.1 to 0.4 μm in terms of diameter. Moreover, the yarn unevenness U% was as large as 1.3%, and the wear resistance performance of the obtained multifilament according to the frosting test was second grade, and clear fibrillation was confirmed. Compared with Example 1, the operability, yarn unevenness U% and abrasion resistance were inferior, and the use was at a level that was considerably limited.

(Comparative Example 6)
The blend ratio (mass ratio) of component A / component B is 30/70, and the ratio of component C (Nippon Catalyst: styrene-2-isopropenyl-2-oxazoline copolymer “Epocross RPS-1005”) is 1.0. A multifilament was obtained in the same manner as in Example 1 except that the mass% was used. In the spinning of Comparative Example 6, fluctuations in the pack pressure were confirmed, and yarn breakage occurred frequently. When the TEM observation of the cross section of the obtained synthetic fiber was performed, the island domain size was 0.03 to 0.4 μm. Further, the yarn unevenness U% was as large as 1.8%, and the wear resistance performance of the obtained multifilament according to the frosting test was second grade, and clear fibrillation was confirmed. Compared with Example 1, the operability, yarn unevenness U% and abrasion resistance were inferior, and the use was at a level that was considerably limited.

(Comparative Example 7)
A multifilament was obtained in the same manner as in Example 1 except that the blend ratio (mass ratio) of component A / component B was 30/70 and component C was not added. In the spinning of Comparative Example 7, yarn breakage occurred twice during sampling. When the cross section of the obtained fiber was observed with a TEM, it was found to have a uniformly dispersed sea-island structure, and the island domain size was 0.03 to 0.2 μm in terms of diameter. As a result of observing the slices with the alkali etching and dissolving and removing the polylactic acid, it was confirmed that most of the sea component was missing and that the polylactic acid formed the sea component. Further, the yarn unevenness U% was as large as 2.3%, and the wear resistance performance of the obtained multifilament according to the frosting test was second grade, and clear fibrillation was confirmed. Compared with Example 1, the operability, the yarn unevenness U% and the abrasion resistance were inferior, and the use was at a level that was considerably limited.

  The results of Comparative Examples 1 to 7 are shown together in Table 3.

1: Spinning hopper 2: Twin screw extrusion kneading machine 3: Spinning block 4: Spinning pack 5: Spinneret 6: Monomer suction device 7: Uniflow cooling device 8: Yarn 9: Oil supply device 10: First take-up roll 11: No. 1 2 take-up roll 12: winding machine 13: winding yarn (cheese package)

Claims (11)

It consists of a polymer alloy formed by blending an aliphatic polyester resin (A), a thermoplastic polyamide resin (B), and a compatibilizer (C), and the compatibilizer (C) is a linear styrene / (/) having a glycidyl group. A synthetic fiber characterized by being a (meth) acrylic ester copolymer.   The synthetic fiber according to claim 1, wherein the aliphatic polyester resin (A) is a synthetic fiber having a sea-island structure in which an island component is formed and the thermoplastic polyamide resin (B) is a sea component.   The synthetic fiber according to claim 1 or 2, wherein the yarn unevenness (U%) is 0.8% or less.   The synthetic fiber according to any one of claims 1 to 3, wherein the aliphatic polyester resin (A) is a crystalline resin and has a melting point of 150 to 230 ° C.   The synthetic fiber according to any one of claims 1 to 4, wherein the thermoplastic polyamide resin (B) is a crystalline resin and has a melting point of 150 to 250 ° C.   The blend ratio (mass ratio) of the aliphatic polyester resin (A) and the thermoplastic polyamide resin (B) is 5/95 to 55/45, and the synthesis according to any one of claims 1 to 5 fiber.   The amount of the compatibilizer (C) added to the total amount of the aliphatic polyester resin (A), the thermoplastic polyamide resin (B) and the compatibilizer (C) is 0.005 to 5% by mass. The synthetic fiber according to any one of claims 1 to 6.   A fiber structure comprising at least a part of the polymer alloy synthetic fiber according to claim 1. Supplying a compatibilizer (C) comprising an aliphatic polyester resin (A), a thermoplastic polyamide resin (B), and a linear styrene / (meth) acrylate copolymer having a glycidyl group to an extrusion kneader And melt-kneading to produce a polymer alloy, and spinning the polymer alloy at a spinning speed of 500 to 5,000 m / min at a spinning temperature of the melting point Tmb + 10 ° C. to the melting point Tmb + 40 ° C. of the thermoplastic polyamide resin (B). A method for producing a synthetic fiber of a polymer alloy characterized by the following.   The method for producing a synthetic fiber according to claim 9, wherein the blend ratio (mass ratio) of the aliphatic polyester resin (A) and the thermoplastic polyamide resin (B) is 5/95 to 55/45.   The amount of the compatibilizer (C) added to the total amount of the aliphatic polyester resin (A), the thermoplastic polyamide resin (B) and the compatibilizer (C) is 0.005 to 5% by mass. The method for producing a synthetic fiber according to claim 9 or 10.