JP2009256857A - Polylactic acid multifilament yarn for yarn dividing, and method for producing polylactic acid monofilament using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid multifilament yarn for yarn dividing having excellent yarn dividing properties which cannot be achieved by conventional studies, and to provide a polylactic acid multifilament yarn for the yarn dividing having excellent quality and properties of passing through high-order processes with little deterioration of physical properties even when formed into monofilaments after the yarn dividing. <P>SOLUTION: The polylactic acid multifilament for filament separation has a single filament fineness of 10-50 dtex, and contains 0.02-1 wt.% of spherical inorganic particles having an average particle diameter of 0.5-7.5 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polylactic acid multifilament for splitting which has an excellent package foam and is excellent in defatting property and splitting property.

  Polylactic acid resin is a carbon neutral material obtained from non-petroleum-based raw materials and has biodegradability. Therefore, polylactic acid resin has recently attracted attention as a material that has a low environmental burden and does not increase the amount of waste.

  In the textile field, various fibers such as multifilament, monofilament, slit yarn, and BCF are being developed. Conventionally, synthetic fibers such as polyester, polyamide, and polyolefin have been used, for example, for vehicle materials, building materials, and forestry. It is being applied to materials and daily life materials.

  However, since polylactic acid fibers are different from conventional synthetic resins such as polyester, polyamide, and polyolefin in physical properties and surface properties, there are many fields where they have not yet been used in earnest.

One of the fields in which polylactic acid fibers are still difficult to use is fiber splitting. Monofilaments obtained by splitting multifilaments are more productive and cost-effective than monofilaments obtained by the direct spinning method, so they are promising in the clothing field such as organdy and living material fields such as tea bags and draining nets. Development of polylactic acid splitting yarn that is a material and is carbon neutral material and biodegradable is desired.
The reason why the polylactic acid fiber cannot be applied to the splitting yarn is its splitting property, and techniques for improving the splitting property of the polylactic acid fiber are described in Patent Documents 1 to 4, for example.

  Patent Document 1 discloses a technique for reducing yarn / thread friction of single yarn in order to suppress breakage of the split yarn due to rubbing between single yarns, and Patent Document 2 discloses that the variation of single yarn fineness is within a specific range. A technology for improving the splitting property by keeping the tension applied to each single yarn at the time of fibering is disclosed in Patent Document 3, which improves the splitting property by setting the load tension applied to the stylus in the entanglement method to be within a specific range. Patent Document 4 discloses a technique for improving the splitting property by setting the number of entanglements to a specific range or less, and various technical developments for obtaining a splitting yarn made of polylactic acid resin have been made. Nevertheless, the polylactic acid resin has not yet been industrially used as a splitting yarn.

  The reason is considered as follows. Patent Document 1 describes a technique for improving the separation property by lowering the yarn / yarn friction of a single yarn. However, when the yarn / yarn friction is simply reduced, traversing occurs frequently during multifilament winding and when transporting multifilament packages, and large tension fluctuations due to traversing occur during unwinding in the fiber separation process. Therefore, there was a problem of breaking the yarn. In addition, since a phenomenon occurs in which the single yarn is twisted between the splitting guide and the winder (running while two or more adjacent single yarns are twisted), the tension between the splitting guide and the winder is excessive. It was necessary to set it high. In addition, polylactic acid fibers cause a sudden drop in physical properties when wound with high tension. Therefore, when all 10kg polylactic acid multifilament packages are split with high tension, the yarn wound by a winder There has been a problem that the physical properties of the inner layer portion of the package are greatly reduced.

  Patent Document 2 describes a technique for improving the splitting property by keeping the tension that each single yarn receives during splitting by making the single yarn fineness variation a specific range. However, although the fluctuation in tension between single yarns due to the reduction in variation in single yarn fineness was suppressed, there was a problem that the above-mentioned twisting phenomenon occurred.

  Patent Document 3 describes a technique for improving the separation property by setting the load tension applied to the stylus in the entanglement method to a specific range or less. Certainly, when the load tension applied to the stylus in the entanglement method is below a certain level, the thread release property is improved, but the above-described twisting phenomenon occurs.

  Patent Document 4 discloses a technique for improving the separation property by setting the number of entanglements to a specific range or less. Certainly, the smaller the number of entanglements, the better the yarn separation, but there is a problem that the above-mentioned twisting phenomenon occurs. In the multifilament manufacturing process, yarn swaying during drawing, yarn twisting with guides, and yarn twisting during winding traverse occurs, so it is very difficult to obtain multifilaments without 100% entanglement or twisting of the yarn. It is difficult to.

  In this way, the development of polylactic acid multifilaments for splitting that has been made so far is based on the knowledge of the development of conventional splitting yarns made of resins such as polyester, nylon, and olefins. The resin has not been able to obtain a multifilament having a fineness that can be applied industrially.

Japanese Patent Laying-Open No. 2005-206991 (Claims) JP-A-2004-277910 (Claims) Japanese Patent Laying-Open No. 2005-133249 (Claims) Japanese Patent Laying-Open No. 2005-163224 (Claims)

  In the present invention, the first problem is to obtain a polylactic acid multifilament excellent in fineness, which cannot be achieved by the conventional studies as described above, and further, polylactic acid excellent in quality and high-process passability The second problem is to obtain a monofilament.

In order to solve the above-mentioned problems, the inventors of the present invention have made extensive studies on the splitting properties of polylactic acid multifilaments, particularly the twisting phenomenon. As a result, it contains 0.02 to 1% by weight of spherical inorganic particles having a single yarn fineness of 10 to 50 dtex and an average particle size of 0.5 to 7.5 μm, and preferably has one or more protrusions per 2000 μm ² of fiber surface. It has been found that polylactic acid multifilament can solve the aforementioned problems. More specifically, the present inventors have found that the polylactic acid multifilament having the above-described structure has excellent splitting properties without occurrence of yarn breakage during splitting due to a package foam, a twisting phenomenon, or the like.
The polylactic acid fiber of the present invention has a spherical inorganic particle having a refractive index in the range of 1.3 to 1.5, a spherical inorganic particle is spherical, It is a preferable form that is a silica particle.

  According to the present invention, polylactic acid multifilaments excellent in passing through the separation process and monofilaments excellent in quality can be obtained. Thus, clothing materials, living materials, industrial materials, etc. using polylactic acid monofilaments can be produced with high productivity and at low cost. Can be obtained.

The polylactic acid polymer used as a raw material for the polylactic acid multifilament for splitting of the present invention is a polylactic acid obtained by polymerizing lactic acid mainly composed of L-lactic acid and / or D-lactic acid. Here, L-lactic acid as a main component means that 60% by weight or more of the constituent components are composed of L-lactic acid, and this is the same when D-lactic acid is the main component. The molecular weight of the polylactic acid polymer is not limited at all, and for example, a polymer having a weight average molecular weight in the range of 100,000 to 300,000 can be used.

  The polylactic acid multifilament of the present invention may be composed of a copolymer of a component copolymerizable with lactic acid, a blended product with another thermoplastic polymer that can be blended, or the like. Examples of the copolymer include cyclic lactones such as ε-caprolactone, α-hydroxy acids such as α-hydroxyisobutyric acid and α-hydroxyvaleric acid, glycols such as ethylene glycol and 1,4-butanediol, Examples thereof include those obtained by copolymerizing one or more monomers selected from dicarboxylic acids such as acids and sebacic acid. Of these, cyclic lactones and glycols are preferred in view of polymer polymerization characteristics. The proportion of copolymerization is not particularly limited, but the monomer to be copolymerized is preferably 100 parts by weight or less, and more preferably 1 to 50 parts by weight with respect to 100 parts by weight of lactic acid. Examples of blendable thermoplastic polymers may include aliphatic polyester polymers such as polycaprolactone, polybutylene succinate, and polyethylene succinate to reduce melt viscosity.

  The polylactic acid polymer may be obtained by esterifying a carboxyl group in the polymer with a compound having a hydroxyl group. Examples of the compound having a hydroxyl group include higher alcohols having 6 or more carbon atoms such as octyl alcohol, lauryl alcohol and stearyl alcohol, and glycols such as ethylene glycol, diethylene glycol and 1,4-butanediol. By esterifying the carboxyl group at the polylactic acid molecule terminal with a compound having a hydroxyl group, the thermal stability during melt spinning and the temporal stability of the fiber after melt spinning can be improved. Among these, from the viewpoint of stretchability, higher alcohols having 6 to 18 carbon atoms are preferable. In order to obtain the same effect, the carboxyl group may be reacted with one or more compounds selected from a carbodiimide compound, an epoxy compound, an oxazoline compound, an oxazine compound, and an aziridine compound. Moreover, the polylactic acid multifilament for splitting used in the present invention is a lubricant, an antioxidant, a heat-resistant agent, a heat-resistant agent, a light-proofing agent, a light-resistant agent, an ultraviolet absorber, and an anti-static agent as long as the effects of the present invention are not impaired. , Pigments, flame retardants, and the like.

  The polylactic acid multifilament for splitting of the present invention contains 0.1 to 5% by weight, more preferably 0.5 to 3% by weight of fatty acid bisamide and / or alkyl-substituted fatty acid monoamide in order to improve wear resistance. % May be contained. If it is less than 0.1% by weight, the effect of improving the wear resistance cannot be sufficiently obtained, and if it exceeds 5% by weight, it is difficult to obtain the required strength. By setting the content of the fatty acid bisamide and / or the alkyl-substituted fatty acid monoamide in the above range, the slipperiness of the filament surface can be improved and excellent wear resistance can be imparted. Fatty acid bisamide refers to a compound having two amide bonds in one molecule such as saturated fatty acid bisamide, unsaturated fatty acid bisamide, aromatic bisamide, etc., for example, methylene biscaprylic amide, methylene biscapric amide, methylene bislaurin. Acid amide, methylene bis myristic acid amide, methylene bis palmitic acid amide, methylene bis stearic acid amide, methylene bis isostearic acid amide, methylene bis behenic acid amide, methylene bis oleic acid amide, methylene biserucic acid amide, ethylene biscapryl Acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bismyristic acid amide, ethylene bispalmitic acid amide, ethylene bisstearic acid amide, ethylene bisisostearic acid Amide, ethylene bis behenic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, butylene bis stearic acid amide, butylene bis behenic acid amide, butylene bis oleic acid amide, butylene bis erucic acid amide, hexamethylene Bistearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bisoleic acid amide, hexamethylene biserucic acid amide, m-xylylene bisstearic acid amide, m-xylylene bis-12-hydroxystearic acid amide, p- Xylylene bis-stearic acid amide, p-phenylene bis-stearic acid amide, p-phenylene bis-stearic acid amide, N, N′-distearyl adipic acid amide, N, N′-distearyl sebacic acid amide, N, N′- Gioray Adipic acid amide, N, N′-dioleyl sebacic acid amide, N, N′-distearyl isophthalic acid amide, N, N′-distearyl terephthalic acid amide, methylene bishydroxystearic acid amide, ethylene bishydroxystearic acid amide , Butylene bishydroxystearic acid amide, hexamethylene bishydroxystearic acid amide, etc., and alkyl-substituted fatty acid monoamides are compounds having a structure in which amide hydrogen such as saturated fatty acid monoamides and unsaturated fatty acid monoamides are replaced with alkyl groups. For example, N-lauryl lauric acid amide, N-palmityl palmitic acid amide, N-stearyl stearic acid amide, N-behenyl behenic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-o Examples include rail stearic acid amide, N-stearyl erucic acid amide, and N-oleyl palmitic acid amide. The alkyl group may have a substituent such as a hydroxyl group introduced into its structure, for example, methylol stearamide, methylol behenic acid amide, N-stearyl-12-hydroxystearic acid amide, N-oleyl-12-hydroxystearic acid amide and the like are also included in the alkyl-substituted fatty acid monoamide of the present invention. Of these, fatty acid bisamides can be more preferably used because they are less reactive with polylactic acid because of the lower reactivity of amides, and are high in heat resistance and difficult to sublimate because of their high molecular weight. The fatty acid bisamide and the alkyl-substituted fatty acid monoamide may be added singly or a plurality of components may be mixed and used.

  However, the polylactic acid multifilament for splitting of the present invention is a biodegradable and non-petroleum-based raw material, and is used as a product with a small environmental impact even when discarded. It is preferable to avoid copolymerization and the like as much as possible and to use various additives that do not use any of the heavy metal compounds and environmental hormone substances as well as the compounds that are currently expected to be concerned. The polylactic acid multifilament for splitting according to the present invention has not only a circular cross section but also an irregular cross section such as a flat shape, a triangular shape, a hollow shape, and a star shape as long as the effect of the present invention is not impaired. Alternatively, core-sheath composite or sea-island composite fibers may be used.

  As described above, improvement of the splitting property of polylactic acid multifilaments has been studied but has not been solved yet. Therefore, as a result of repeated studies on the drawing conditions, winding conditions, oil agent type, oil agent adhesion amount, degree of entanglement on the drawing roller, the number of single yarns, additives, etc., the results of polylactic acid multifilament separation With regard to improvement in fineness, especially the above-mentioned phenomenon of twisting, the main factors for improving the fineness of conventional polyethylene terephthalate multifilaments and nylon multifilaments are reduced yarn thread friction, single yarn fineness variation, entanglement strength, etc. Was only a minor factor, and the main factor was that the surface of the single yarn was too smooth.

This is presumably because when the molten polylactic acid polymer is discharged from the die, the solidification speed of the discharged single yarn is slow, so that the surface becomes smooth due to the polymer surface tension.
The reason why the twisting phenomenon is suppressed when the surface is too smooth is not clear, but since the surface of the single yarn is too smooth, the single yarns attract each other due to the surface tension due to moisture and residual oil in the atmosphere attached between the single yarns. It is thought that power is generated.

  As a result of various investigations to solve this problem, it is characterized by containing 0.02 to 1% by weight of spherical inorganic particles having a single yarn fineness of 10 to 50 dtex and an average particle size of 0.5 to 7.5 μm. It has been found that a polylactic acid multifilament for splitting can solve the above problems. The solving means will be described in detail below.

  The polylactic acid multifilament for splitting of the present invention needs to contain 0.02 to 1% by weight of spherical inorganic particles having an average particle size of 0.5 to 7.5 μm. By adding spherical inorganic particles, it is possible to form minute convex portions on the surface of the single yarn, to reduce the contact area between the single yarns, and to reduce the force with which the single yarns attract each other due to surface tension. Furthermore, when the spherical inorganic particle shape to be used is spherical, not only winding and splitting can be performed without damaging adjacent single yarns, but also damage to the spinning machine and splitting machine can be reduced. The spherical inorganic particles in the present invention are preferably non-porous, and in order to obtain non-porous and spherical fine particles, spherical inorganic particles obtained by a synthesis method are preferred instead of the usual pulverization method.

  The spherical inorganic particles referred to in the present invention are particles whose individual particle shapes are very close to a spherical shape, preferably particles that are close to a true sphere and are not flat or polygonal. More preferably, the circularity is 1 to 1.5, and more preferably the circularity is 1 to 1.2. Here, the circularity refers to a value obtained by dividing the circumference of a particle obtained when the particle is observed with a microscope by the circumference of a circle equal to the area of the particle.

On the other hand, when the spherical inorganic particles are not spherical, for example, in the case of a porous material, the moisture absorption to the particles increases, so that the hydrolysis proceeds during the polylactic acid multifilament melt spinning for splitting, or due to moisture absorption during actual use. The hydrolysis that progresses. In addition, if the particles are polygonal with many sharp corners, such as needle crystals, damage to the spinning machine, fiber splitting machine, and adjacent single yarns will increase, and there will be other than twilling and twisting during fiber splitting. The thread breaks due to factors (deterioration due to guide adhesion scratches, damage from adjacent single yarn).
The polylactic acid multifilament for splitting of the present invention needs to have a spherical inorganic particle content of 0.02 to 1% by weight, and the spherical inorganic particle content is preferably 0.05 to 0.5% by weight, 0.05 to 0.3% by weight is more preferable. When the content of the spherical inorganic particles is less than 0.02% by weight, the frequency with which the convex portion is formed on the surface of the single yarn is low, and there is a high possibility that the effect of the present invention is not exhibited. On the other hand, when the content of spherical inorganic particles exceeds 1% by weight, the pulling force between single yarns is too low. When unwinding in this way, there is a problem that the tension fluctuation due to the traversing or filament dropping becomes large and the yarn breaks.

The average particle size of the spherical inorganic particles contained in the polylactic acid multifilament for splitting of the present invention is required to be 0.5 to 7.5 μm, preferably 0.5 to 5 μm, more preferably 1 A range of ˜3 μm can be exemplified. When the average particle diameter is less than 0.5 μm, the convex portion formed on the surface of the single yarn becomes small, and thus the effect of the present invention is hardly exhibited. On the other hand, when the average particle diameter exceeds 7.5 μm, the pulling force between single yarns is too low. When wrinkling, not only the fluctuation in tension due to the above-mentioned traversing or filament dropping increases, the frequency of yarn breakage increases, but also the particle diameter is too large, which causes a deterioration in the spinning performance during spinning drawing.
The polylactic acid multifilament for splitting of the present invention preferably has one or more convex portions per 2000 μm ² of the single yarn surface. The convex portion is a convex portion having a diameter of 1 to 10 μm due to the spherical inorganic particles, and when one or more convex portions due to the spherical inorganic particles are present per 2000 μm ² , the single yarns are in contact with each other. It is possible to reduce the area and reduce the pulling force of the single yarns by the surface tension described above. Originally there is no upper limit to the number of convex parts, but the number of convex parts per 2000 μm ² is 100 or less from the viewpoint of not reducing the attracting force between single yarns too much, that is, not reducing the convergence during winding. It is preferable that As a more preferable range of the number of convex portions existing per 2000 μm ^{2 of the} single yarn surface, 3 to 50 can be exemplified.

Moreover, the polylactic acid multifilament for splitting of the present invention has a single yarn fineness of 10 to 50 dtex, and preferably 20 to 40 dtex. The strength is preferably 2 to 6 cN / dtex, and more preferably 3 to 5 cN / dtex.
When the strength is less than 2 cN / dtex, there is a high possibility of yarn breakage in the separation process or the weaving process. Further, although there is no inherent upper limit in strength, there is a problem that the cost is increased, for example, in order to obtain a polylactic acid multifilament for splitting with a strength exceeding 6 cN / dtex, it is necessary to add ultra-multistage drawing or addition of a special drug. In order to obtain good yarn production with the current general production equipment, 6 cN / dtex or less is good.

  Further, when the single yarn fineness exceeds 50 dtex, traversing and filament dropping at the time of multifilament winding are likely to occur, and the possibility that the fineness is deteriorated becomes extremely high. On the other hand, when the single yarn fineness is less than 10 dtex, there is a very high possibility that the single yarn will break due to tension or abrasion in the fiber separation process.

  The polylactic acid multifilament for splitting of the present invention preferably has a boiling yield of 5 to 20%. When the boiling yield exceeds 20%, there is a high possibility that the dimensional stability after the product is deteriorated. Moreover, the lower the boiling yield, the better. However, the boiling yield is preferably 5% or more from the same viewpoint as the aforementioned strength.

  The polylactic acid multifilament for splitting of the present invention preferably has an elongation of 20 to 50%, and a more preferable range is 30 to 45%. Since the polylactic acid multifilament for splitting of the present invention contains spherical inorganic particles, when stretched at a high tension such that the elongation is less than 20%, voids are generated between the spherical inorganic particles and the polylactic acid polymer. The possibility of whitening of the fibers increases. On the other hand, if the elongation exceeds 50%, there is a high possibility that the formation of the fiber structure will be undeveloped, and there may be variations in physical properties in the longitudinal direction.

  The total fineness of the polylactic acid multifilament for splitting of the present invention is preferably 200 to 500 dtex. When the total fineness is less than 200 dtex, the productivity is poor. When the total fineness is more than 500 dtex, twilling or filament dropping is likely to occur at the time of winding the multifilament.

  The yarn dynamic friction coefficient of the single yarn constituting the multifilament of the present invention is preferably in the range of 0.12 to 0.14, and more preferably in the range of 0.125 to 0.14. . When the yarn dynamic friction coefficient satisfies the above range, the yarn dynamic friction is too low, and it is difficult for the yarn to fall and filament fall off during unwinding, and the yarn friction is too high. It becomes possible to suppress the occurrence of twisting.

  In order to obtain a single yarn having a yarn dynamic friction coefficient within the above range, a smoothing agent component contained in the oil agent, for example, mineral oil, silicone synthetic lubricating oil, adipic acid ester, aliphatic carboxylic acid, ester obtained from higher alcohol Method of changing the type and combination, addition amount, etc., method of adding a smoothing agent such as ethylene bisstearyl amide to the resin before spinning, contact between yarn and yarn by forming a convex part on the surface of single yarn by adding particles A method of reducing the area can be exemplified, but from the viewpoint of stability of the yarn dynamic friction coefficient over time, a method of forming a convex portion on the surface of the single yarn by adding particles is preferable.

In addition, in the multifilament used for splitting, the smaller the number of single yarns, the smaller the number of single yarns in the yarn-making process, so it is advantageous. However, the number of single yarns is 5 or more when productivity is taken into consideration. It is preferable. On the other hand, when the number of single yarns is too large, the number of single yarns is preferably 20 or less because there are many opportunities for the single yarns to be entangled with each other in the yarn making process and the splitting properties deteriorate. Further preferred examples of the number of single yarns include 5 to 16.
One of the excellent features of the polylactic acid polymer is that it has good transparency. For example, when a transparent monofilament base fabric obtained by splitting transparent polylactic acid multifilaments is used as a tea bag, it is preferable that the multifilaments and monofilaments are transparent because the tea leaves can be enjoyed visually. In the prior art, the addition of particles has not been studied from the viewpoint of maintaining this transparency.

  In the case of using various particles such as titanium oxide and talc, spherical inorganic particles within the scope of the present invention can obtain polylactic acid multifilaments excellent in unwinding property and separation property. As a result of repeated studies on spherical inorganic particles and polylactic acid multifilaments for splitting, the inventors used spherical inorganic particles having a refractive index of 1.3 to 1.5, preferably 1.4 to 1.5. In some cases, it has been found that yarn can be produced while maintaining the transparency of the polylactic acid multifilament for splitting. When the refractive index is out of the above range, the fiber is whitened, making it difficult to obtain a transparent monofilament.

  Examples of the spherical inorganic particles having a refractive index of 1.3 to 1.5 include silica, and the silica is preferably treated with a silane coupling agent. There is no particular limitation on the silane coupling agent to be used, and phenyl silane, phenylamino silane, methacrylic silane, vinyl silane, epoxy silane, etc. can be used, but compatibility with polylactic acid and dispersibility are possible. It is preferable to select in consideration.

  Although the polylactic acid multifilament for splitting of the present invention as described above can be produced by the method described below, the production method is not limited at all. The polylactic acid polymer used for the production of the polylactic acid multifilament for splitting of the present invention preferably has a weight average molecular weight (Mw) of 100,000 to 300,000, more preferably Mw of 200,000 to 300,000. A range can be illustrated. When a polymer having an Mw of less than 100,000 is used, there is a possibility that a polylactic acid multifilament for splitting having a strength that can withstand the tension during splitting cannot be stably obtained. When a polymer having Mw exceeding 300,000 is used, stable melt production may be difficult because the melt viscosity is too high. In addition, the water content of the polylactic acid polymer used for melt spinning is preferably 0 to 200 ppm in order to suppress hydrolysis of the polymer.

  There is no particular limitation on the method of adding the spherical inorganic particles to the polylactic acid multifilament for splitting. The method of adding as a powder when the polymer is melted in a spinning machine, and the spherical inorganic particle powder is applied to the polylactic acid polymer chip. A method, a method of adding as a slurry, a method of kneading spherical inorganic particles in a polylactic acid polymer in advance, etc. may be adopted. However, from the standpoints of handling, spinning, cost, etc., a method of kneading spherical inorganic particles in advance with a polylactic acid polymer, especially a master chip in which spherical inorganic particles are kneaded at a high concentration and a polylactic acid polymer chip not containing spherical inorganic particles Are preferably used for spinning. The polylactic acid polymer is melted with an extruder-type spinning machine or the like, measured with a gear pump or the like, removed with a metal non-woven filter or the like, and then discharged from the base hole.

  The spinning temperature depends on the melting point of the polylactic acid polymer to be used, and although it can be changed depending on the presence or absence of a copolymer component, it is usually set to 190 to 250 ° C, more preferably 200 to 240 ° C. When the spinning temperature is less than 190 ° C., sufficient fluidity may not be obtained when the polymer is melted. On the other hand, when the spinning temperature exceeds 250 ° C., thermal decomposition proceeds in the spinning machine, so that it may be difficult to obtain a polylactic acid multifilament for splitting with good spinning properties.

  Immediately below the spinneret, the upper end is 0 to 15 cm from the spinneret surface, and a range of 5 to 100 cm from the upper end is surrounded by a heating tube and / or a heat insulating tube, and the spinning yarn is placed in a high temperature atmosphere of 200 to 280 ° C. Passing is a preferred form of the production method of the present invention.

  The spun yarn is not cooled immediately, but is gradually cooled through a high-temperature atmosphere surrounded by the heating tube and / or the heat insulating tube, thereby relaxing the orientation of the spun yarn and between the single fibers. Molecular alignment uniformity can be improved. Further, by passing the spun yarn through a high temperature atmosphere without immediately cooling it, there is an advantage that no gap is generated at the interface between the spherical inorganic particles and the polylactic acid polymer. On the other hand, if it cools immediately without letting it pass in a high temperature atmosphere, the orientation of an undrawn yarn will increase and the orientation degree distribution between single fibers will become large. When such an undrawn yarn is heat-drawn, there is a possibility that a polylactic acid multifilament for splitting having a strength that can withstand the splitting tension as a result cannot be obtained. Furthermore, when rapidly cooled, an air layer is generated at the interface between the spherical inorganic particles and the polylactic acid polymer, and the fibers may be whitened or the stretchability may be deteriorated.

  The unstretched yarn that has passed through the high-temperature atmosphere is then preferably cooled and solidified by blowing air at 10 to 100 ° C., preferably 15 to 75 ° C. When the cooling air is less than 10 ° C., a large cooling device is required separately from the normal device, which is not preferable. In addition, when the cooling air exceeds 100 ° C., the single yarn swaying during spinning becomes large, so that the single yarns collide with each other, making it difficult to produce fibers with good yarn forming properties. The air cooling device may be a horizontal blowing type or an annular blowing type.

  The oil agent is then applied to the cooled and solidified unstretched yarn. The oil agent may be aqueous or non-aqueous, but contains a smoothing agent as a main component, includes a surfactant, an antistatic agent, an extreme pressure agent component, etc., and removes an active component in the polylactic acid polymer. It is preferable to use an oil agent composition.

  The unstretched yarn to which the oil is applied is wound around a take-up roller (1FR) and taken up. The surface speed of 1FR, that is, the take-up speed is preferably 300 m / min or more, more preferably 500 m / min or more. Although the physical properties of the polylactic acid multifilament for splitting of the present invention can be obtained even at a take-off speed of less than 300 m / min, it is difficult to adopt because the production efficiency is low. Although there is no particular upper limit to the take-up speed, the take-up speed is preferably 5000 m / min or less, more preferably 3000 m / min or less in the case of industrially stable production.

The undrawn yarn taken up at the take-up speed is drawn once or continuously without being taken up. Similarly to 1FR, a Nelson type roller having two rollers as one unit is arranged side by side with 2FR, 1DR, 2DR, and a relaxation roller (RR), and the yarn is successively wound to perform a drawing heat treatment. Usually, stretching is performed between 1FR and 2FR to focus the yarn. A preferred stretch ratio is in the range of 1 to 7%, more preferably 1 to 5%. 1FR is heated to 50 to 80 ° C., preferably 50 to 70 ° C., and the take-up yarn is preheated and sent to the next drawing step.
Stretching is performed between 2FR and 1DR, and between 1DR and 2DR. Depending on the target physical properties, the number of rollers may be increased, multi-stage stretching such as 3 or 4 stages may be adopted, or the number of rollers may be reduced to 1 stage. It can also be drawn. At this time, in order to reduce rubbing between the roller surface and the polylactic acid multifilament for splitting containing spherical inorganic particles, the roller is preferably a satin roller with low friction, and the roughness of the roller surface is Ra = 0. A chromium-plated material having a thickness of 3 to 5 μm, preferably Ra = 0.5 to 3 μm, can be suitably used.

  The first stage stretching is performed between 2FR and 1DR, the temperature of 2FR is 80 to 120 ° C, preferably 80 to 110 ° C, and the temperature of 1DR is 90 to 120 ° C, preferably 100 to 120 ° C. When the number of stretching stages is two, the stretching ratio of the first stage is set in the range of 30 to 90%, preferably 50 to 90% of the total stretching ratio.

  The second stage stretching is performed between 1DR and 2DR, and 2DR is 110 to 160 ° C, preferably 115 to 145 ° C. In the case of two-stage stretching, the remaining stretching of the first-stage stretching ratio is performed between the total stretching ratios. The stretched yarn is subjected to a relaxation treatment of 0 to 7%, preferably 0 to 3%, more preferably 0% between the RR and not only to remove the strain caused by the hot drawing, but also achieved by drawing. It is possible to fix the formed highly oriented structure, or to relax the orientation of the amorphous region and lower the thermal shrinkage rate. RR uses a non-heated roller or a roller heated to 160 ° C. or less. Usually, RR becomes a temperature of 90 to 150 ° C. regardless of the presence or absence of heating due to the heat brought in by the yarn heated at the time of hot drawing.

  The yarn subjected to the relaxation heat treatment is preferably wound on a winder with a winding tension of 0.05 to 0.4 cN / dtex. When the winding tension is less than 0.05 cN / dtex, package form collapse is likely to occur, and as a result, the unwinding property at the time of splitting may deteriorate. According to the knowledge of the present inventors, since the polylactic acid polymer causes a decrease in physical properties under tension, the winding tension is preferably 0.4 cN / dtex or less.

  The polylactic acid multifilament for splitting of the present invention preferably has a winding thickness (paper tube to package outermost layer distance: mm) / winding width (traverse width: mm) to a paper tube or the like of 1 to 1/2. When the winding thickness with respect to the winding width exceeds 1/2, the surface layer is liable to fall off and the filament to fall off. On the other hand, there is essentially no lower limit to the winding thickness length with respect to the winding width, and the shorter the winding thickness length with respect to the winding width, the less likely the twilling and filament dropping occur, but the production of the yarn obtained by dividing the multifilament From the viewpoint of properties, the winding thickness with respect to the winding width is preferably 1/10 or more.

  In the conventional polylactic acid multifilament for splitting as described in the above cited document, it is required that there is no entanglement or twisting of the yarn, so only a narrow stretching temperature range is required to suppress yarn swing on the roller. It has been a problem that it cannot be employed, that it cannot be relaxed, and that twisting of the yarn due to the traverse of the winder section has become a problem. However, since the polylactic acid multifilament for splitting of the present invention obtained by the above method can suppress the twisting phenomenon more than the conventional polylactic acid multifilament for splitting, A wider range of spinning conditions can be employed than the method of manufacturing the filament, resulting in excellent productivity.

  However, also in the polylactic acid multifilament for splitting of the present invention, it is preferable from the viewpoint of splitting properties to avoid positive confounding using, for example, an air guide. In the present invention, the entanglement means that the yarns are entangled with each other to give the yarn a converging property as used by those skilled in the art. For example, the yarn as detected by the hook drop method of JIS L1013. In the polylactic acid multifilament for splitting of the present invention, the number of entanglements is preferably 0 to 2, and more preferably 0 to less than 1.

  On the other hand, in the multifilament of the present invention, it is preferable that there is at least one twist of single yarn per 1 m of yarn length. In order not to impair the effects of the present invention, the number of twists per 1 m of yarn length is preferably 50 or less. Here, the twist of the single yarn is recognized when, for example, the yarn is placed on a plane such as a preparation and observed with an optical microscope, and at least one of the yarns placed on the plane is adjacent to the adjacent single yarn. If the twist of the single yarn is within the range of the present invention, the phenomenon of exceeding at least one yarn can be suppressed at the same time, both the filament dropping during winding and the twisting phenomenon during splitting.

  The splitting method of the present invention is a multifilament splitting method for splitting a parent yarn to obtain a child yarn, wherein the polylactic acid multifilament for splitting of the present invention is used as the parent yarn. By using the polylactic acid multifilament for splitting of the present invention as the parent yarn, it becomes possible to simultaneously satisfy the unwinding property and splitting property required at the time of splitting. Here, the child yarn usually refers to a single filament of a multifilament, that is, a monofilament, but since the splitting method of the present invention is very excellent in splitting properties, two or more monofilaments are used as continuous yarns during winding. It may be wound on a package.

  The separation method of the present invention can use a known separation device, so that no increase in cost or deterioration of handling property due to special modification is observed.

  In the splitting method of the present invention, the splitting tension of the polylactic acid multifilament for splitting, that is, the tension applied to the polylactic acid monofilament between the splitting guide and the winder is preferably 0.5 to 3 cN / dtex. 0.8 to 2.5 cN / dtex is more preferable. When the splitting tension is less than 0.5 cN / dtex, there is a tendency for polylactic acid monofilaments to bend due to insufficient tension. On the other hand, when the splitting tension exceeds 3 cN / dtex, the load applied to the polylactic acid monofilament is too large, and the physical properties of the polylactic acid monofilament may be lowered.

In the fiber separation method of the present invention, it is preferable that the polylactic acid monofilament is separated with a tension of 0.5 to 3 cN / dtex, wound once, and then rewinded with a tension of 0.03 to 0.5 cN / dtex. It is a form. The reason for this is as described above. Since polylactic acid progresses with time under tension, it is preferable to rewind at a tension of 0.03 to 0.5 cN / dtex in order to suppress the progress. .
The polylactic acid monofilament immediately after splitting is preferably immediately subjected to a rewind process. The rewind tension is preferably 0.5 cN / dtex or less, and more preferably 0.25 cN / dtex or less. Since polylactic acid fibers tend to be deteriorated in physical properties under tension, there is a concern that the monofilament physical properties may deteriorate over time when the polylactic acid monofilament wound up with high tension is not rewound as in the fiber separation process.
The rewind tension may be measured usually just before winding the polylactic acid monofilament, for example, between the splitting guide and the guide of the winder, and the method is not limited at all.

  The polylactic acid monofilament of the present invention is characterized by being a monofilament obtained by dividing the polylactic acid multifilament for splitting of the present invention, and is a monofilament having excellent splitting properties. Furthermore, since the polylactic acid monofilament of the present invention contains spherical inorganic particles as described above, the interaction with other single yarns is small, for example, the so-called barabique phenomenon during weaving hardly occurs, and the weft yarn during weaving It also has excellent running properties.

  The polylactic acid monofilament of the present invention is preferably wound around a bobbin and / or pan. Compared with cheese-like packages, bobbins and / or pan-like packages are less likely to fall when rolled up, and polylactic acid has excellent processability in the subsequent process even when wound in a low tension range as in the present invention. A monofilament can be supplied.

  Since the polylactic acid monofilament obtained by the present invention is excellent in quality, can be obtained at a low cost with high productivity, living materials such as organdy, tea bags, draining nets, vehicle materials such as car seats, interiors such as curtains, etc. It can be suitably used for materials and the like.

  Hereinafter, embodiments of the present invention will be described in more detail by way of examples. Definitions and measuring methods of characteristics used in the specification text and examples are as follows.

  [Average particle diameter]: The average particle diameter was determined by wet measurement using water as a solvent, using a particle size distribution measuring machine (SK Laser Micronizer LMS-350: manufactured by Seishin Enterprise).

  [Weight average molecular weight of polylactic acid]: Tetrahydrofuran was mixed with the sample chloroform solution to obtain a measurement solution. This was measured by gel permeation chromatography (GPC-150C manufactured by Waters), and the weight average molecular weight Mw and the number average molecular weight Mn were calculated in terms of polystyrene, and the degree of dispersion Mw / Mn was determined.

  [Melting point]: Using a differential scanning calorimeter DSC-7 manufactured by Perkin Elmer Co., Ltd., a temperature at which an extreme value of a melting endothermic curve obtained by measuring 20 mg of a sample at a heating rate of 5 ° C./min is expressed as a melting point (° C. ).

  [Total Fineness]: JIS L1013 (1999) 8.3.1 Positive Fineness a) According to the A method, the predetermined load was measured at 5 mN / tex × display tex number and predetermined yarn length 90 m.

  [Single yarn fineness]: obtained by dividing the total fineness obtained by the above measurement method by the number of single yarns.

  [Strength and Elongation]: The sample was measured with a “TENSILON” UCT-100 manufactured by Orientec Co., Ltd. under the constant speed elongation condition shown in the JIS L1013 (1999) 8.5.1 standard time test. At this time, the grip interval was 25 cm, the pulling speed was 30 cm / min, and the number of tests was 10 times. The elongation at break was determined from the elongation at the point showing the maximum strength in the SS curve.

[Boiling]: Measured according to the method of JIS L1013 (1999). Cases were collected from the yarn package with a measuring machine, and the length L1 was measured by applying a load of 0.09 cN / dtex. Subsequently, the load was removed and the treatment was performed in boiling water for 30 minutes. The casserole after the boiling water treatment was air-dried, the load of 0.09 cN / dtex was applied again to measure the casserole length L2, and the boiling yield was measured by the following formula.
Boiling yield (%) = [(L1-L2) / L1] × 100.

[Number of convex portions]: A single yarn was gold-deposited using an ion coater (IB-3 manufactured by Eiko Engineering Co., Ltd.), observed using SEM (ABT-55 manufactured by Topcon Corporation), and a convex per 10000 μm ^{2 of} the single yarn surface. The number of parts (convex parts having a diameter of 1 to 10 μm) was counted and converted to the number per 2000 μm ² . The observation magnification at this time may be changed as appropriate depending on the filament fineness.

  [Winding tension]: Monitoring was performed using Tenion Pickup (BTB1-R03) manufactured by Eiko Sokki Co., Ltd. and Tension Meter (HS-3060) manufactured by Eiko Sokki Co., Ltd. as a detector. Winding was performed at a winding time of 60 minutes, the tensions at winding times of 10, 20, 30, 40, and 50 minutes were measured, and the average value was taken as the winding tension.

[Fabricity]: The fluff generation frequency was measured over a length of 1 million m with a fluff detection device installed at the relaxation roll outlet, and the number of fluff per 10,000 m was determined according to the following formula.
Number of fuzz per 10,000 m = number of fuzz per million m / 100.

  [Full pipe ratio]: When 10 polylactic acid multifilament packages were split using a Kanda Giken straight splitting machine, 90% or more of the winding amount could be split continuously without breaking the yarn. While calculating | requiring the number of lactic acid multifilament packages, the frequency | count of the yarn breakage resulting from twilling off and the yarn breakage number resulting from twisting were counted.

[Weaving property] A plain woven fabric was woven from polylactic acid monofilaments obtained by splitting using a slewer type loom at a weaving density of 350 pieces / inch and a weaving machine rotation speed of 250 rpm.
Weaving was performed until weaving yarn breakage occurred or until the weaving length reached 100 m, and the number of times that a base fabric having a weaving length of 100 m was obtained among three weaving tests was measured.

  [Base fabric quality] Observe whether or not there is a barbique (displacement) in 1 square meter of the base fabric obtained in the weaving test. A base fabric with two or more barabiques has a cross of × and a barbique of one or less. The base fabric was judged as ○.

  [Refractive index] Methanol was put into a test tube, spherical inorganic particles to be measured were added thereto, and dispersion was performed by stirring and ultrasonic irradiation to prepare a basic evaluation sample. At this time, when a refractive index deviation occurs between the refractive index n20 of the spherical inorganic particles to be measured and methanol, the solution in the test tube looks white. Next, 1-bromonaphthalene having the next highest refractive index was dropped dropwise to increase the refractive index of the solvent. As the solution is dropped, when the refractive indexes of the solvent and the filler coincide, the solution in the test tube is visually observed transparently. The value obtained by measuring the refractive index n20 of the transparent solution with a refractometer was taken as the refractive index of the particles.

[Color tone] The base fabric was cut into 10 cm x 20 cm, and 3 g of tea leaves were put inside and sewed to obtain a tea bag of 10 cm x 10 cm. 10 adult women were allowed to observe the obtained tea bags, and the number of people who judged that the base fabric was excellent in transparency and the internal tea leaves looked good was counted. [Thread Yarn Friction Coefficient] Monofilament after splitting yarn speed 55m Pass through a pulley with a diameter of 35 mm per minute, friction angle 180 °, pulley entry side tension: T1 = 10 g, measurement temperature 20 ° C. ± 5 ° C., humidity 60% RH ± 10%, pulley exit side tension: T2 The measurement was performed for 30 seconds, and the dynamic friction coefficient between yarns was calculated by the following equation. For the measurement of the tension, a traveling yarn friction coefficient measuring machine manufactured by Eikoh Industries, Ltd. was used for both T1 and T2.
Yarn dynamic friction coefficient (μd) = 0.4697 × Log (T2 / T1).

[Production Example 1] (Production of polylactic acid polymer)
Lactide prepared from L-lactic acid having an optical purity of 99.5% was converted into bis (2-ethylhexanoate) tin catalyst (lactide to catalyst molar ratio = 10,000: 1), GE Ultranox 626 (lactide to Ultranox 626 weight). The polylactic acid polymer having a weight average molecular weight of 200,000 and a melting point of 168 ° C. obtained by polymerization at 180 ° C. for 350 minutes in a nitrogen atmosphere in the presence of a ratio = 99.8: 0.2) was vacuum dried at 105 ° C. P1 having a moisture content of 60 ppm was obtained.

[Production Example 2] (Method for producing spherical silica-containing polylactic acid master chip)
P1 weighed to a final silica concentration of 10% by weight and spherical silica particles having an average particle size of 0.25 μm, 0.7 μm, 1.3 μm, 2.5 μm, 3.5 μm, 10 μm, and 1.0 μm were mixed. The resulting master chip was melt-kneaded at a temperature of 200 ° C. using a twin screw extruder and vacuum-dried at 105 ° C. to obtain P2, P3, P4, P5, P6, P7, and P10 having a moisture content of 80 ppm.

[Production Example 3] (Manufacturing method of polylactic acid master chip containing polygonal silica)
P1 weighed so that the final silica concentration is 10% by weight and polygonal silica particles (refractive index of 1.45 by immersion method) obtained by the pulverization method with an average particle diameter of 3.5 μm are mixed and biaxial extrusion The resulting master chip was melt-kneaded at a temperature of 200 ° C. using a machine and vacuum-dried at 105 ° C. to obtain P8 having a moisture content of 80 ppm.

[Production Example 4] (Method for producing calcium carbonate-containing polylactic acid master chip)
P1 weighed to a final calcium carbonate concentration of 10% by weight and heavy calcium carbonate particles (refractive index of 1.66 by immersion method) having an average particle diameter of 2 μm were mixed, and a twin screw extruder was used. The resulting master chip was melt-kneaded at a temperature of 200 ° C. and vacuum-dried at 105 ° C. to obtain P9 having a moisture content of 92 ppm.

(Examples 1-12, Comparative Examples 1-7)
P1 to P10 were chip-blended so that the inorganic particle type and the inorganic particle concentration in the polylactic acid multifilament were as shown in Table 1 or Table 2, and melt-spun at 220 ° C. using an extruder-type spinning machine. The melted polymer is filtered through a 20 μm metal nonwoven fabric filter in a spinning pack, and then, with a gear pump, the hole diameter is 0.6 mm and the hole length is 1.25 mm so that the single yarn fineness described in Table 1 or Table 2 is obtained. Spinning was performed from a die having a hole in a ring shape so that the number of single yarns was reached.

  A 30 cm heating cylinder and a 15 cm heat insulating cylinder were attached immediately below the base surface, and heated so that the atmosphere temperature in the heating cylinder was 250 ° C. Here, the in-cylinder atmosphere temperature is an air layer temperature in a central portion of the heating cylinder length and a portion 1 cm away from the inner wall. An annular blow-off chimney was attached directly under the heat insulating cylinder, and cold air at 30 ° C. was blown onto the yarn at a speed of 30 m / min to cool and solidify, and then an oil agent was applied to the yarn. Oils include iso-C24 alcohol / thiodipropionic acid ester (40% by weight), C11-15 alcohol AOA / thiodipropionic acid ester (30% by weight), trimethylolpropane AOA distearate (10% by weight), C8 alcohol AOA (10 wt%) Hardened castor oil (7 wt%) and stearylamine EO15 (3 wt%) diluted with mineral oil to 20% were used as a non-aqueous oil agent.

The unstretched yarn to which the oil agent was applied was wound around a Nelson type roller (1FR: surface speed 670 m / min: surface temperature 50 ° C .: number of yarns 5 times) with two rollers as a pair. The take-up yarn was wound around the next Nelson type roller (2FR: surface speed of 680 m / min: surface temperature of 100 ° C .: number of yarns of 5 times) without winding up, and the yarn was aligned. For the aligned yarn, three sets of Nelson rollers (1DR, 2DR, RR) that are sequentially installed are used, and the first stage is stretched between 2FR-1DR and the second stage between 1DR-2DR. Was subjected to a relaxation treatment between 2DR and RR. The surface speed, surface temperature, and power of each roller are as follows.
1DR: surface speed 2700 m / min: surface temperature 110 ° C .: 5 times 2DR: surface speed 3050 m / min: surface temperature 135 ° C .: 8 times RR: surface speed 3000 m / min: unheated: 4 times relaxation The treated yarn was wound around a cheese-like package (9 kg) with a winder at the winding tension shown in Table 1 to obtain a polylactic acid multifilament for splitting having the characteristics shown in Table 1 or Table 2. . The obtained polylactic acid multifilament cheese-shaped package for splitting was split with a splitting tension of 0.7 cN / dtex using a straight splitting machine manufactured by Kanda Giken, and wound into a panic. Table 1 or Table 2 shows the result of splitting at this time and the color tone of the obtained monofilament.

  As is clear from Tables 1 and 2, the polylactic acid multifilament for splitting of the present invention was the result of satisfying the yarn forming property and splitting property at the same time. In Example 9, which was carried out in the same manner as Example 1 except for the winding tension, although it was at the production level, the full pipe ratio was slightly inferior to that in Example 1, but it was sufficient. The thread breakage at this time was not due to twilling or twisting, but was presumed to be due to a partial drop in fiber strength, and the winding tension was high, so under tension It is considered that the polylactic acid fiber is slightly deteriorated.

(Example 13)
The polylactic acid monofilament pan obtained in Example 1 was subjected to a weaving process after 400 hours had elapsed from the splitting. The raw yarn physical properties and weaving evaluation results at this time are shown in Table 3.

(Examples 14 to 16)
The polylactic acid monofilament pan obtained in Example 1 was rewinded with the tension shown in Table 1 immediately after splitting and stored for 400 hours. After storage for 400 hours, the raw yarn was subjected to a weaving process immediately after measuring the strength. The raw yarn physical properties and weaving evaluation results at this time are shown in Table 3.

(Comparative Example 8)
The same procedure as in Example 14 was performed except that the polylactic acid monofilament pan obtained in Comparative Example 2 was used.

  As is apparent from the results in Table 3, the polylactic acid multifilament for splitting of the present invention has physical properties that can withstand actual use even after splitting, and the obtained monofilament satisfies both weaving properties and base fabric quality at the same time. It is. In particular, a base fabric made of monofilaments using spherical inorganic particles having a refractive index of 1.45, which is a preferred embodiment of the present invention, was excellent in transparency.

  Since the polylactic acid multifilament of the present invention reduces the environmental load and is excellent in color tone and fineness, polylactic acid monofilaments excellent in quality can be produced with high yield. In addition, the monofilament obtained by splitting the multifilament of the present invention can be applied to a wide range of uses such as living materials, clothing materials, industrial materials, medical materials, etc. for which polyethylene terephthalate and polyamide monofilaments have been used. The utility value of is very high.

Claims (6)

A polylactic acid multifilament for splitting, comprising 0.02 to 1% by weight of spherical inorganic particles having a single yarn fineness of 10 to 50 dtex and an average particle size of 0.5 to 7.5 μm. The polylactic acid multifilament for splitting according to claim 1, which has one or more convex portions per 2000 μm ^{2 of} fiber surface. The polylactic acid multifilament for splitting according to claim 1 or 2, wherein the spherical inorganic particles have a refractive index of 1.3 to 1.5. The polylactic acid multifilament for splitting according to any one of claims 1 to 3, wherein the spherical inorganic particles are silica particles. The polylactic acid multifilament for splitting according to any one of claims 1 to 4, wherein a yarn dynamic friction coefficient of a single yarn constituting the multifilament is 0.12 to 0.14. The manufacturing method of the polylactic acid monofilament which divides | segments using the polylactic acid multifilament for splitting in any one of Claims 1-5 as a parent yarn.