JP2008255526A - Crimped yarn and carpet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crimped yarn produced by using a polylactic acid which is an eco-friendly material, free from the defects of polylactic acid comprising poor crimp tendency, bulkiness and abrasion resistance, and suitable as a carpet. <P>SOLUTION: The crimped yarn is a multifilament yarn comprises a sheath-core conjugate fiber comprising a core component composed of a polylactic acid composition, and a sheath component composed of a polyamide composition, wherein the ratio of the core component is 10-50 wt.%, the noncircularity (C) of the core component is 1.2-9, the noncircularity (S) of the sheath component is 2-6, and the ratio of the noncircularity (C) of the core component to the noncircularity (S) of the sheath component (C/S) is 0.6-1.5. The invention further provides a carpet produced by using the crimped yarn. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a crimped yarn comprising a core-sheath composite fiber in which the core component is a polylactic acid composition and the sheath component is a polyamide composition. In particular, the present invention relates to a crimped yarn suitable as a carpet, which has improved crimp properties, bulkiness, and abrasion resistance, which are disadvantageous characteristics of polylactic acid.

  In recent years, in order to prevent depletion of fossil fuel resources and to prevent global warming, development has been actively carried out to replace synthetic fibers made of conventional petroleum polymers with aliphatic polyester polymers made from plant resources. .

  Among them, polylactic acid fibers have been actively developed because there is a possibility that they can be used as practical products in terms of mechanical properties and thermal properties, and recently, polymer costs are becoming realistic prices. However, in spite of great expectations, there are few applications that can make use of the characteristics of polylactic acid fibers as they are, and technical development has been carried out to improve the defect characteristics of polylactic acid, but the results are not sufficient. For this reason, the production and sales volume of polylactic acid fibers is still small, and early expansion is eagerly desired.

  In particular, the market for automobile carpets and interior carpets is large, and despite the expectation of early conversion to environmentally friendly materials such as polylactic acid, crimping is a drawback of polylactic acid crimped yarn. The reality is that carpet properties such as wear resistance and wear resistance have not been cleared, and have not yet been commercialized.

  Under such circumstances, apart from the technological development that makes the best use of the characteristics of polylactic acid or drastically improves the defect characteristics, a part of the synthetic fiber is replaced with polylactic acid fiber by mixing with the conventional synthetic fiber. Attempts have been made to do so. Specifically, it relates to a polymer blend or a core-sheath composite of polylactic acid and polyamide. Examples of techniques disclosed so far include Patent Document 1 and Patent Document 2.

  Patent Document 1 discloses a technique related to a resin composition in which a polyamide is blended with polylactic acid to form a sea-island structure for the purpose of improving heat resistance and wear resistance. However, in the resin composition described in Patent Document 1, although the polyamide is uniformly dispersed in the polylactic acid, the polylactic acid component that is the main component is partially exposed on the fiber surface. In the crimping process, high-temperature heat treatment was not possible, and high crimping was insufficient. In addition, although the polylactic acid component is exposed to the fiber surface, it is at a level that does not pose any problem for wear resistance under relatively low loads, such as clothing, but wear resistance under high loads required for carpets. Was still inadequate.

On the other hand, Patent Document 2 discloses a technique relating to a core-sheath composite fiber in which the core component is polylactic acid and the sheath component is polyamide for the purpose of improving wear resistance. However, since the composite fiber described in Patent Document 2 is a technique in which polylactic acid is simply coated with polyamide, interfacial peeling between the core and the sheath easily occurs due to an external force during heat treatment or actual use. In the case of crimped yarn, high temperature treatment was not possible, and high crimping was insufficient. In actual use, the interface between the core and the sheath is peeled off, resulting in a change in appearance (white blurring), and further, the core component polylactic acid is exposed, resulting in a decrease in wear resistance under high loads. There was a problem of sexual defects.
JP 2003-238775 A (Claims) JP 2004-36035 A (Claims)

  The present invention has been achieved as a result of studying the solution of the problems in the prior art described above as an issue. Specifically, it is a crimped yarn using polylactic acid, which is an environmentally friendly material, and provides a crimped yarn suitable as a carpet with improved crimpability, bulkiness and wear resistance, which are the disadvantages of polylactic acid. There is to do.

  The above-mentioned problem is a multifilament composed of core-sheath composite fibers in which the core component is a polylactic acid composition and the sheath component is a polyamide composition, and the ratio of the core component is 10 to 50% by weight, the degree of deformity of the core component (C) is 1.2 to 9, the degree of deformity (S) of the sheath component is 2 to 6, and the ratio (C / S) of the degree of deformity (C) of the core component to the degree of deformity (S) of the sheath component is 0. This can be achieved by a crimped yarn characterized by being 6 to 1.5.

  According to the present invention, as will be described below, a carpet that is a crimped yarn using polylactic acid, which is an environmentally friendly material, but has improved crimp properties and wear resistance, which are disadvantageous properties of polylactic acid, A crimped yarn suitable as the above can be provided.

  The present invention is described in detail below.

  The present invention is a multifilament composed of a core-sheath composite fiber in which the core component is a polylactic acid composition and the sheath component is a polyamide composition, and the core component ratio is 10 to 50% by weight, C) is 1.2 to 9, sheath component irregularity (S) is 2 to 6, core component irregularity (C) and sheath component irregularity (S) ratio (C / S) is 0.6 It is a crimped yarn characterized by being -1.5.

  In the present invention, the polylactic acid in the polylactic acid composition of the core component refers to a polymerized lactic acid oligomer such as lactic acid or lactide. Since lactic acid has two types of optical isomers, D-lactic acid and L-lactic acid, the polymer is poly (D-lactic acid) consisting only of D isomer and poly (L-lactic acid) consisting only of L isomer, and There is polylactic acid consisting of both. As the optical purity of D-lactic acid or L-lactic acid in polylactic acid decreases, the crystallinity decreases and the melting point drop increases. Since the melting point is preferably 150 ° C. or higher in order to maintain the heat resistance of the fiber, the optical purity is preferably 90% or higher.

  In addition, when poly (D-lactic acid) having an optical purity of 90% or more and poly (L-lactic acid) having an optical purity of 90% or more are blended so that the weight ratio is 40/60 to 60/40, a stereo complex Since the melting point can be increased to 220 to 230 ° C. by the formation of crystals, it is more preferable.

  Residual lactide exists as a low molecular weight residue in polylactic acid, but these low molecular weight residues may cause poor processability due to contamination of the die, heating roller, and crimp nozzle in the spinning, drawing, and crimping processes. In addition to this, it becomes a cause of inducing staining abnormalities such as dyed spots in the dyeing process. In addition, the hydrolysis of polylactic acid is promoted, and the durability of the fiber product is lowered. Therefore, the amount of residual lactide in polylactic acid is preferably 0.3% by weight or less, more preferably 0.1% by weight or less, and still more preferably 0.03% by weight or less. As a method for measuring the residual lactide, 1 g of a sample (polylactic acid) was dissolved in 20 ml of dichloromethane, 5 ml of acetone was added to this solution, and the solution was fixed with cyclohexane and precipitated, followed by liquid chromatography using GC17A manufactured by Shimadzu Corporation. And a method for obtaining a lactide amount by an absolute calibration curve.

  The molecular weight of polylactic acid is preferably higher in order to increase the wear resistance. However, if the molecular weight is too high, the stretchability tends to decrease, such as frequent yarn breakage and fluffing in the yarn making process. The weight average molecular weight is preferably 80,000 or more, more preferably 100,000 or more in order to maintain wear resistance. More preferably, it is 120,000 or more. On the other hand, when the molecular weight exceeds 350,000, the stretchability is lowered as described above. Therefore, the weight average molecular weight is preferably 350,000 or less, and more preferably 300,000 or less. More preferably, it is 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 polyamide in the polyamide composition of the sheath component preferably has a melting point of 160 to 240 ° C. If the melting point is less than 160 ° C., only mechanical and thermally inferior fiber properties can be obtained, and crimping at high temperatures becomes difficult. On the other hand, if the melting point exceeds 240 ° C., the difference in melting point from the polylactic acid as the core component becomes too large, and therefore polylactic acid tends to be thermally deteriorated at the spinning temperature at which the polyamide is melted.

  In addition, the polyamide of the present invention may be a copolymer with other polyamide components mainly composed of polycapramide or caprolactam. Examples of preferred copolymer are 100 parts by weight of the entire copolymer, caprolactam: 99 to 80 parts by weight and 1 to 20 parts by weight of hexamethylene adipamide, trimethylene adipamide, hexamethylene sebacamide and the like. This is a partially copolymerized polyamide. Polycapramide has traditionally been a suitable material for crimped carpets. Copolyamides based on the polycapramide component have a slightly lower crystallinity than polycapramide, but have a melting point close to that of polylactic acid. In the spinning process, the thermal degradation of polylactic acid is reduced, the occurrence of yarn breakage and fluff is suppressed, and stable yarn production becomes possible.

  The present invention particularly relates to a crimped yarn using polylactic acid. In order to compensate for the drawbacks of polylactic acid that have been fatal in crimped yarns using polylactic acid, that is, crimpability failure and wear resistance failure, the characteristics of polyamide as a sheath component are utilized to the maximum. There is a need to. For this reason, the inventors have focused on preventing interfacial peeling between the core and the sheath and exposing the core component, and as a result of intensive studies, the present invention has been achieved.

  That is, the crimped yarn of the present invention can be heat-treated at the time of crimping, and peels off the interface between the core and the sheath and changes in appearance (white blur) due to external forces such as friction received in actual use, and further exposes the core component. The ratio of the core component is 10 to 50% by weight, the deformity (C) of the core component is 1.2 to 9, the deformity (S) of the sheath component is 2 to 6, The ratio (C / S) of the degree of irregularity (C) and the degree of irregularity (S) of the sheath component is 0.6 to 1.5.

  When the ratio of the core component is less than 10% by weight, the amount of polylactic acid used is reduced, and the merit as an environmentally friendly material is reduced. On the other hand, when the ratio of the core component exceeds 50% by weight, there is a high possibility that a part of the core component is exposed on the surface of the fiber in the modified cross-section yarn. The ratio of the core component is more preferably 15 to 35% by weight.

  If the degree of deformity (C) of the core component is less than 1.2, the contact area between the core and the sheath is reduced, and stress concentration at the core-sheath interface is excessive due to heat treatment and external force. As a result, the core component is easily exposed. On the other hand, when the degree of deformity (C) of the core component exceeds 9, the outer diameter of the core component is close to the outer diameter of the sheath component, and the possibility that the core component is exposed increases. The deformability (C) of the core component is more preferably 1.5 to 7.5.

  When the degree of deformity (S) of the sheath component is less than 2, the possibility of exposing the core component is increased, and since the gap between the single fibers is reduced as a multifilament, the bulkiness of the carpet becomes insufficient. . Moreover, since the contact area of a heating roller or a heating fluid and a single yarn becomes small at the time of a crimping process, it becomes difficult to apply a crimp. On the other hand, it is difficult to stably produce a composite fiber having a sheath component having an irregularity degree (S) of more than 6 with the current technology. The deformity (S) of the sheath component is more preferably 2.5-5.

  Even if the ratio (C / S) of the deformity (C) of the core component to the deformity (S) of the sheath component is less than 0.6 or exceeds 1.5, the core component may be exposed. Becomes higher. Also, if it is less than 0.6, the contact area between the core and the sheath becomes small, and stress concentration at the core-sheath interface with respect to heat treatment and external force becomes excessive, so that core-sheath peeling, white blurring, and exposure of the core component occur. It becomes easy.

  The degree of irregularity referred to in the present invention is the ratio of the diameter of the circumscribed circle to the diameter of the inscribed circle in multi-leaf sections such as Y-type and X-type, ie, (diameter of circumscribed circle / diameter of inscribed circle). It is represented by

  The crimped yarn of the present invention is preferably a polyamide composition in which the sheath component contains 0.1 to 2 parts by weight of titanium oxide with respect to 100 parts by weight of polyamide, and contains 0.5 to 1.5 parts by weight. It is more preferable. By containing 0.1 to 2 parts by weight of titanium oxide, it becomes possible to reduce the friction coefficient with the friction body and the friction coefficient between single fibers by roughening the fiber surface, and further, excessive friction. Even when white blur occurs due to peeling of the core-sheath interface due to the force, the change in appearance can be reduced by the light shielding effect of titanium oxide.

  When titanium oxide is less than 0.1 parts by weight, the above effect is small, and when it exceeds 2 parts by weight, the effect is saturated. On the other hand, in melt spinning, the spinning property is lowered due to aggregation of titanium oxide. If necessary, the core component may also contain 0.1 to 2 parts by weight of titanium oxide with respect to 100 parts by weight of polylactic acid.

  The crimped yarn of the present invention is preferably a polyamide composition in which the sheath component contains 0.1 to 2 parts by weight of pigment with respect to 100 parts by weight of polyamide, and 0.5 to 1.5 parts by weight is contained. Is more preferable. The core-sheath interface peeling may be manifested by a difference in contraction rate or a difference in contraction stress between the core component and the sheath component due to heat treatment in the dyeing process. Therefore, in order to eliminate the necessity of the dyeing process, it is preferable to contain 0.1 to 2 parts by weight of a pigment in advance at least in the sheath component. If the pigment is less than 0.1 parts by weight, the color development is small, and if it exceeds 2 parts by weight, the spinning property is lowered due to aggregation of the pigment in melt spinning. Further, if necessary, the core component may contain 0.1 to 2 parts by weight of a pigment with respect to 100 parts by weight of polylactic acid.

  Although it does not specifically limit as a pigment to be used, The following pigment is illustrated. Oxide-based inorganic pigments excluding lead, chromium and cadmium, ferrocyanide inorganic pigments, silicate inorganic pigments, carbonate inorganic pigments, phosphate inorganic pigments, carbon black, aluminum powder, bronze powder and titanium powder coated mica, etc. Selected from organic pigments such as inorganic pigments, phthalocyanine organic pigments, perylene organic pigments, isointoserinone organic pigments, and heterocyclic dyes, helinone dyes, perylene dyes and thioindio dyes Or a combination of two or more. More specifically, examples of inorganic pigments include titanium oxide, zinc white, titanium yellow, zinc-iron-based brown, titanium-cobalt green, cobalt green, cobalt blue, copper-iron-based black oxides, and bitumen. Ferrocyanides, silicates such as ultramarine, carbonates such as calcium carbonate, phosphates such as manganese violet, carbon black, aluminum powder and bronze powder, and titanium powder-coated mica are used. Lead, chromium and Inorganic pigments containing heavy metals such as cadmium are not used. As the organic pigment, phthalocyanine series such as copper phthalocyanine blue, copper phthalocyanine green and brominated copper phthalocyanine green, perylene series such as perylene scarlet, perylene la, perylene maroon, isoindolinone, etc. are used. As the dye, anthraquinone, heterocyclic, helinone, perylene, and thioindio are used. Further, the pigment can be used in combination with a commonly used dispersant.

  The crimped yarn of the present invention is not intended to reduce wear resistance in actual use due to deterioration of the polyamide of the sheath component due to heat or ultraviolet irradiation, or to induce peeling of the core-sheath interface, white blur, and exposure of the core component. It is preferable that at least the sheath component contains an antioxidant and / or an ultraviolet absorber. Moreover, you may contain antioxidant and / or a ultraviolet absorber also in a core component as needed.

  The antioxidant is not particularly limited, and known ones can be used. Examples thereof include phenolic antioxidants, sulfur antioxidants, phosphorus antioxidants, copper compounds, and the like. The polylactic acid may be contained in an amount of 0.01 to 1 part by weight with respect to 100 parts by weight of the polyamide in the sheath component. Moreover, a copper compound has the effect which suppresses deterioration of a polymer by coordinating to an amide bond, and can be used conveniently. Specific examples of copper compounds include copper chloride, copper bromide, copper iodide, copper sulfate, copper nitrate, copper carbonate, copper phosphate, copper acetate, copper salicylate, copper stearate, copper benzoate, and succinic acid. Examples thereof include copper, copper phthalate, copper pyrophosphate, and complex compounds of the inorganic copper halide with xylylenediamine, 2-mercaptobenzimidazole, benzimidazole, and the like. A copper compound should just contain 0.001-0.02 weight part with respect to 100 weight part of polylactic acid in a core component and 100 weight part of polyamide in a sheath component as a copper weight. In the case of using a copper compound, lithium chloride, lithium bromide, lithium iodide, potassium chloride, potassium bromide, potassium iodide, sodium bromide, iodine for the purpose of suppressing the release of metallic copper during melt spinning. An alkali halide compound such as sodium halide may be used in combination. One kind of antioxidant may be used, or a plurality of antioxidants may be used in combination.

  As the UV absorber, known ones can be used without particular limitation. For example, salicylic acid UV absorber, benzophenone UV absorber, benzotriazole UV absorber, benzimidazole UV absorber, cyanoacrylate UV Absorbers, ultraviolet stabilizers, hindered amine light stabilizers and the like can be mentioned, and the core component may contain 0.01 to 1 part by weight with respect to 100 parts by weight of polylactic acid and the sheath component with respect to 100 parts by weight of polyamide. In addition, a ultraviolet absorber may be 1 type and may use multiple together.

  Specific examples of the antioxidant and the ultraviolet absorber include compounds described in “12093 Chemical Products (Chemical Industry Daily)”.

  In addition, other additives such as plasticizers, surfactants, lubricants, crystal nucleating agents, flame retardants, antistatic agents, deodorants, antibacterial agents, and other functional agents may be added as necessary. May be.

  The crimped yarn of the present invention preferably has a crimp elongation after treatment with boiling water of 10 to 40% and a boiling yield of 0 to 10%.

  If the crimp elongation rate is 10 to 40%, the crimp property is remarkably superior to that of conventional crimp yarns using polylactic acid, it is highly crimped and has a sense of volume. When used, the settling resistance and texture will be good. If the crimp elongation rate is less than 10%, it is not enough, which is not much different from the conventional crimped yarn using polylactic acid. On the other hand, when the crimping elongation rate exceeds 40%, stable crimping is difficult and the texture of the carpet may become hard due to excessive volume. The crimp elongation is more preferably 15 to 30%. In addition, if the boiling yield exceeds 10%, a dimensional change occurs during the dyeing process and actual use, which is not preferable. The boiling yield is preferably 0-6%.

  The total fineness of the crimped yarn of the present invention is preferably 500 to 3000 dtex, more preferably 1000 to 2000 dtex. If it is less than 500 dtex, if it is tufted as a carpet pile as it is, it will be necessary to raise stitches in order to obtain a practical weight, making tufting difficult. Even if twisted yarn is used and used as a cut pile of various twisted yarns, the fineness is too low and it is necessary to raise the gauge and stitch more than necessary, which is not preferable. If it exceeds 3000 dtex, uniform cooling and solidification is difficult in the yarn making process, heat transfer is not sufficiently performed, stretchability and crimping workability are remarkably lowered, and stable yarn production cannot be performed. .

  The single yarn fineness of the crimped yarn of the present invention is preferably 5 to 50 dtex. If it is less than 5 dtex, it is not preferable for a carpet because it lacks wear resistance, sag resistance and tread resistance. If it exceeds 50 dtex, the texture becomes coarse and not preferred for carpet use.

  The strength of the crimped yarn of the present invention is preferably 1.5 to 4.0 cN / dtex. If it is less than 1.5 cN / dtex, the strength is too low, the wear resistance is low, and the practical durability is insufficient. On the other hand, the strength exceeding 4.0 cN / dtex cannot be achieved with the current technology.

  The crimped yarn of the present invention may contain other fibers to form a carpet. For example, it may be natural fiber, recycled fiber, semi-synthetic fiber, alignment with synthetic fiber, twisted yarn, mixed fiber. Other fibers include natural fibers such as cotton, linen, wool, and silk, regenerated fibers such as rayon and cupra, semi-synthetic fibers such as acetate, nylon, polyester (polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, Polylactic acid etc.), synthetic fibers such as polyolefin, polyacrylonitrile and polyvinyl chloride are applicable.

  In addition, the crimped yarn of the present invention is suitable not only for home and office carpets but also for interior materials for automobiles. Among them, it is suitable for line mats and optional mats for automobiles that require high wear resistance and sag resistance.

  Although the manufacturing method of the crimped yarn of this invention is not specifically limited, For example, the following method is illustrated.

  After drying, the polylactic acid chips and polyamide chips having a moisture content of 0.05% or less were melted in separate melt-kneaders, then weighed with separate gear pumps, led to a spin pack, After merging into a core-sheath shape, it is discharged. The moisture content is measured in accordance with JIS K0068 by the water vaporization-coulometric titration method of Karl Fischer titration under the conditions of (polymer melting point−10 ° C.) × 20 minutes.

  As a method for adding titanium oxide, pigment, antioxidant, and UV absorber, it may be added when polymerizing each polymer, or may be added when melt spinning, but it is melted for ease of handling. It is preferable to add at the time of spinning. In this case, the addition method includes a master batch method, a liquid addition method or a powder addition method, and the master batch method is preferable from the viewpoint of productivity and blend stability.

  When using the master batch method, a master chip in which various additives are added to a molten base polymer is prepared in advance, and this is metered and mixed with a polylactic acid chip or a polyamide chip during melt spinning. The master chip may be added with one or more additives as required. Moreover, the master chip obtained in this way can be used in combination of one or more as required. In addition, for the purpose of improving the kneadability of the additive to the polymer, a static kneader ("Static Mixer" or "High Mixer") in which the melted polymer is incorporated in the polymer pipe between the melt kneader and the spin pack or in the spin pack. -") Is preferably used.

  The spinning temperature is set to the melting point Tm to Tm + 40 ° C. of the polymer having the higher melting point among polylactic acid and polyamide to be used.

  In the crimp hole, the crimped yarn has a core component irregularity (C) of 1.2 to 9, a sheath component irregularity (S) of 2 to 6, a core component irregularity (C) and a sheath component What is necessary is just to set the slit ratio of a core side and a sheath side suitably so that ratio (C / S) of an irregularity degree (S) may be set to 0.6-1.5. What is necessary is just to set the slit ratio of 2-20 and a sheath side to 3-15. The slit ratio is expressed by (slit length / slit width) from the slit length and slit width in the multi-leaf section yarn cap.

  A fiber oil agent is applied to the yarn discharged from the die and cooled and solidified, and then stretched and heat-treated. For the stretching, a multistage thermal stretching method of one stage or two or more stages is adopted. It is also possible to use a steam processing device or the like in combination for auxiliary fixing of the stretching point or heat treatment. In order to perform the crimping process effectively, the molecular chain needs to be properly oriented and crystallized. The draw ratio varies depending on the degree of orientation and crystallinity of the undrawn yarn, such as the spinning speed and cooling conditions, but is usually drawn in a range of 2 to 4 times. For example, in the case of two-stage stretching, the heat stretching temperature is 30 to 80 ° C. for the first-stage stretching roller, 80 to 150 ° C. for the second-stage stretching roller, and 150 to 220 ° C. for the final roller after stretching. To do.

  Next, the hot drawn yarn is continuously wound or once wound and then crimped. Crimping is performed by heating fluid processing through a crimping device. The crimped yarn of the present invention is usually crimped by a jet nozzle method having a crimped nozzle, and a yarn passing through the needle is contacted with a high-pressure high-temperature fluid such as heated steam from the surroundings, and the atmosphere It is crimped by releasing it and cooling it. The temperature of the hot fluid is 150 to 280 ° C, preferably 180 to 250 ° C, and saturated steam, superheated steam, or heated air is used.

  Furthermore, for the purpose of fixing the crimps, a method of blowing cool air to the crimped yarns that have passed through the crimping nozzles or depositing the crimped yarns on the surface of the rotary filter that is sucked into the cooling yarn is also used.

  The crimped yarn that has been crimped is imparted with an appropriate stretch to make the crimp partially latent, and then wound up by a winder. The crimped yarn may be subjected to an entanglement process to give convergence before winding.

  Although the manufacturing method of the carpet using the crimped yarn of this invention is not specifically limited, For example, the following methods are employable.

The crimped yarn of the present invention is used as a face yarn, and a carpet is manufactured using a normal tufting apparatus. In general, when the basis weight is 300 to 2000 g / m ² and the pile height is in the range of 3 to 20 mm, the carpet is easy to tuft, has excellent texture and volume.

  Tufted carpets are dyed and backed by known methods. Staining may be continuous dyeing, Wins dyeing, loop dyeing, or the like. Of course, a carpet using a crimped yarn containing a pigment can be backed without being dyed.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited at all by these Examples. In addition, the measuring method of each measured value in an Example is as follows.

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

(2) Relative viscosity of polyamide 0.25 g of a sample was dissolved in 25 ml of 98% sulfuric acid and measured at 25 ° C. using an Ostwald viscometer. The relative viscosity was determined from the ratio of the number of seconds that the polymer solution and sulfuric acid dropped.

(3) Melting point (Tm)
The measurement was performed using a DSC-7 differential scanning calorimeter manufactured by Perkin-Elmer. The sample amount was 20 mg, measured at a rate of temperature increase of 10 ° C./min, and the peak temperature of the melting endothermic curve was taken as the melting point.

(4) Slit ratio In the Y-type cross-sectional yarn cap, it was calculated by the following formula.
Slit ratio = slit length / slit width

(5) Deformation degree of core component (C), Deformation degree of sheath component (S)
The Y-shaped cross-section yarn was cut in a direction perpendicular to the fiber axis, and the cross section was photographed at 200 times using an optical microscope (VH-6300 manufactured by Keyence Corporation). Twenty cross-sections were selected from the photograph, and the diameter of the circumscribed circle and the diameter of the inscribed circle were measured for each component. Calculated by the following formula, the average value was defined as the degree of irregularity.
Deformity = diameter of circumscribed circle / diameter of inscribed circle

(6) Total fineness JIS L 1013 (1999) 8.3.1 Positive fineness b) According to the B method, the initial load is 0.882 mN / dtex, the official moisture content is 0.5% for polylactic acid, 4% for polyamide. Using 5%, it measured using the case where it calculated from JIS L 0105 3.1 (1) absolute dry mixing rate.

(7) Single yarn fineness This was determined by dividing the total fineness by the number of filaments.

(8) Strength and Elongation The sample was measured with Orientec Co., Ltd. “TENSILON” UCT-100 under the constant speed elongation conditions shown in JIS L1013 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.

(9) Boiling yield The sample length (L1) when a load of 0.882 mN / dtex was applied to the sample before boiling water treatment, and dipped in boiling water at 98 ° C. for 30 minutes in an unloaded state and then dried. A sample length (L2) when a load of 0.882 mN / dtex was applied to the sample having the equilibrium moisture content was calculated by the following formula, and the average value of 10 samples was taken as the boiling yield.
Boiling yield (%) = [(L1-L2) / L1] × 100

(10) Crimp elongation after boiling water treatment After winding the crimped yarn, it is left in a cheese-shaped atmosphere at 20 ° C. and a relative humidity of 65% for 20 hours, then left for 24 hours in a skein and then in boiling water. The crimp elongation rate when immersed in is shown, specifically, the value measured by the following method.

That is, the crimped yarn to be measured is immersed in 98 ° C. boiling water for 20 minutes in an unloaded state and then dried to obtain an equilibrium moisture content. An initial load of 0.0176 mN / dtex is applied to this sample. A sample length of 50 cm (L3) measured after 30 seconds was marked, then a constant load of 0.882 mN / dtex was applied to the sample, and the elongation (L4) after 30 seconds was measured. ) And (L4), and the average value of 10 samples was used as the crimp elongation after boiling water treatment.
Crimp elongation after treatment with boiling water (%) = [(L4-L3) / L3] × 100

(11) Spinning property The number of yarn breaks in a 5-hour spinning test was used as an index of spinning property.

(12) Weight per unit area Measured by the method defined in JIS L1021 (1999) 7.3.1.

(13) Pile height The length from the surface of the carpet base fabric (pile root) to the tip of the pile was measured and determined from the average value at 10 locations.

(14) Bulkiness of carpet From the sense of volume and swelling when stepping on a carpet, sensory evaluation was performed using the following indices. Ten testers evaluated the bulkiness from the average value.
A: There is a feeling of volume and swelling, and the quality is particularly good.
B: Good volume and swelling.
C: Insufficient volume and swelling.
D: There is no volume and swelling, and the quality is poor.

(15) Appearance Change of Carpet A test piece having a diameter of 120 mm was cut out from the carpet and attached to a Taber abrasion tester specified in ASTM D1175, and subjected to 100 rotation wear with a wear wheel CS # 10 and a load of 500 g. Then, the surface state of this test piece was observed, and the appearance change was evaluated by the following index.
A: No change in appearance (white blur).
B: Although there is a slight change in appearance (white blur), there is no problem.
C: Appearance change (white blur) has occurred.
D: Appearance change (white blur) is remarkably generated.

(16) Abrasion resistance of carpet A test piece having a diameter of 120 mm was cut out from the carpet and attached to a Taber abrasion tester specified in ASTM D1175, and subjected to 500 rotation wear as a wear wheel CS # 10 and a load of 500 g. From the pile weight (W1) before wear of this test piece and the pile weight (W2) after wear, the wear loss rate was calculated by the following equation.
Abrasion weight loss rate (%) = ((W1-W2) / W1) × 100

(17) Abrasion resistance after ultraviolet irradiation of carpet A test piece having a diameter of 120 mm was cut out from the carpet and irradiated with a xenon weather meter (“SX75W” manufactured by Suga Test Instruments Co., Ltd.), irradiation intensity of 150 W / m ² , no water, 63 ° C. After irradiating with ultraviolet rays under the condition of 80 hours, it was attached to a Taber abrasion tester specified in ASTM D1175, and was subjected to 500 rotation wear as a wear wheel CS # 10 and a load of 500 g. From the pile weight (W3) before wear of the test piece and the pile weight (W4) after wear, the wear loss rate was calculated by the following equation.
Wear loss rate (%) = ((W3-W4) / W3) × 100

[Example 1]
A polylactic acid chip having a weight average molecular weight of 200,000 and a melting point of 170 ° C. (6400D manufactured by Nature Works) and a polyamide (nylon 6) chip (T-100 manufactured by Toray Industries, Inc.) having a relative viscosity of 2.6 and a melting point of 225 ° C. Each was melted at 230 ° C. and 250 ° C. in a uniaxial melt kneader. Each melted polymer is kneaded with an eight-stage static mixer in each polymer pipe, then weighed with a separate gear pump, led to a spinning pack at 250 ° C., and each melted polymer has 96 Y-shaped holes (core side slits). It was discharged after being joined into a core-sheath shape with a die having a ratio: 7 and a slit ratio on the sheath side: 7). (Discharge rate of core component (polylactic acid composition): 81.5 g / min, discharge rate of sheath component (polyamide composition): 190 g / min, (ratio of core component (polylactic acid composition): 30% by weight) )

  The spun yarn was cooled and solidified with a uniflow type chimney, and then an oil agent was applied with an oil agent roller. The yarn provided with the oil agent was taken up by a first roller (non-heated) having a surface speed of 750 m / min, and then continuously subjected to a stretching process. The yarn passed through the first roller is continuously connected to a second roller (50 ° C.) at a speed of 773 m / min, a third roller (140 ° C.) at a speed of 2280 m / min, and a fourth roller (190 ° C.) at a speed of 2626 m / min. Then, stretching was performed, and subsequently, fluid crimping with steam was performed with a crimping nozzle (nozzle temperature 230 ° C., nozzle pressure 0.9 MPa). Thereafter, it was cooled with a rotary filter of 21 m / min, and wound at 2060 m / min to obtain a crimped yarn of 1320 dtex, 96 filaments. The spinning property was good, and the polymer was not fused on the drawing roller after the spinning test.

The obtained crimped yarn is tufted with a basis weight of 350 g / m ² , a pile height of 6.0 mm, and dyed in dark gray with an acid dye under the conditions of 98 ° C. × 30 minutes, whereby a carpet made of cut pile is obtained. Produced. Table 1 shows the characteristics of the crimped yarn and the carpet using the crimped yarn.

[Example 2]
Instead of the “T-100” chip, a titanium oxide master chip (11 parts by weight of titanium oxide with 100 parts by weight of T-100 manufactured by Toray Industries, Inc.) was kneaded into the uniaxial melt kneader on the sheath side. Crimping is carried out in the same manner as in Example 1 except that the master chip is continuously metered with a measuring instrument and titanium oxide is supplied in an amount of 1 part by weight with respect to 100 parts by weight of the polyamide in the sheath component. Yarn and carpet were obtained. Each characteristic is shown in Table 1.

[Example 3]
In addition, an original master chip (master chip containing 11 parts by weight of carbon black as a pigment for 100 parts by weight of T-100 manufactured by Toray Industries, Inc.) is continuously connected to a sheath-side uniaxial melt kneader with a measuring instrument. In the same manner as in Example 2, except that the pigment was supplied in an amount of 0.2 parts by weight with respect to 100 parts by weight of the polyamide in the sheath component while the carpet was not dyed. Yarns and carpets were obtained. Each characteristic is shown in Table 1.

[Example 4]
As an antioxidant, copper iodide is 0.02 part by weight (0.006 part by weight as copper weight) with respect to 100 parts by weight of polyamide in the sheath component, and potassium iodide is used for the purpose of suppressing release of metallic copper. 0.02 part by weight with respect to 100 parts by weight of the polyamide in the sheath component, and, as the ultraviolet absorber, benzotriazole-based ultraviolet absorber (“Tinuvin 328” manufactured by Ciba Specialty Chemicals Co., Ltd.) 100 parts by weight of the polyamide in the sheath component A crimped yarn and a carpet were obtained in the same manner as in Example 3 except that a chip obtained by dry blending these with a “T-100” chip in advance so as to be 0.1 part by weight was used. Each characteristic is shown in Table 1.

[Example 5]
A crimped yarn and a carpet were obtained in the same manner as in Example 1 except that a base having a Y-shaped hole (slit ratio on the core side: 3.3, slit ratio on the sheath side: 3.3) was used. . Each characteristic is shown in Table 1.

[Example 6]
A crimped yarn and a carpet were obtained in the same manner as in Example 1 except that a base having a Y-shaped hole (slit ratio on the core side: 1.2, slit ratio on the sheath side: 3.3) was used. . Each characteristic is shown in Table 1.

[Example 7]
A crimped yarn and a carpet were obtained in the same manner as in Example 1 except that a base having a Y-shaped hole (slit ratio on the core side: 12, slit ratio on the sheath side: 7) was used. Each characteristic is shown in Table 1.

[Example 8]
Discharge amount of core component (polylactic acid composition): 27.15 g / min, discharge amount of sheath component (polyamide composition): 244.35 g / min, (ratio of core component (polylactic acid composition): 10% by weight Except for the change to), crimped yarn and carpet were obtained in the same manner as in Example 1. Each characteristic is shown in Table 1.

[Example 9]
Discharge amount of core component (polylactic acid composition): 135.75 g / min, discharge amount of sheath component (polyamide composition): 135.75 g / min, (ratio of core component (polylactic acid composition): 50% by weight Except for the change to), crimped yarn and carpet were obtained in the same manner as in Example 1. Each characteristic is shown in Table 1.

[Comparative Example 1]
Discharge rate of core component (polylactic acid composition): 190 g / min, discharge rate of sheath component (polyamide composition): 81.5 g / min, (ratio of core component (polylactic acid composition): 70% by weight) A crimped yarn and a carpet were obtained in the same manner as in Example 1 except for the change. The spinning performance was extremely poor, and polylactic acid was fused on the drawing roller after the spinning test. Each characteristic is shown in Table 2.

[Comparative Example 2]
A crimped yarn and a carpet were obtained in the same manner as in Comparative Example 1 except that the third roller was changed to 110 ° C and the fourth roller was changed to 150 ° C. Lowering the roller temperature improved the spinning performance compared to Comparative Example 1. However, the crimped stretch rate of the crimped yarn was as low as 8%, and the bulkiness of the carpet was insufficient and the quality was extremely poor. It was. Each characteristic is shown in Table 2.

[Comparative Example 3]
A crimped yarn and a carpet were obtained in the same manner as in Example 1 except that a base having a Y-shaped hole (core side: round hole, sheath side slit ratio: 7) was used. The spinning performance was extremely poor, and polylactic acid was fused on the drawing roller after the spinning test. Each characteristic is shown in Table 2.

[Comparative Example 4]
A crimped yarn and a carpet were obtained in the same manner as in Example 1 except that a base having a Y-shaped hole (slit ratio on the core side: 14, slit ratio on the sheath side: 7) was used. The spinning property was poor, and the polylactic acid was fused on the drawing roller after the spinning test. Each characteristic is shown in Table 2.

[Comparative Example 5]
A crimped yarn and a carpet were obtained in the same manner as in Example 1 except that a base having a Y-shaped hole (slit ratio on the core side: 1.4, slit ratio on the sheath side: 1.4) was used. . Since the deformity on the sheath side was as low as 1.3, the bulkiness of the carpet was insufficient and the quality was poor. Each characteristic is shown in Table 2.

Claims (6)

  A multifilament composed of a core-sheath composite fiber comprising a polylactic acid composition as a core component and a polyamide composition as a sheath component, wherein the ratio of the core component is 10 to 50% by weight, and the degree of deformity (C) of the core component is 1.2-9, the degree of deformity (S) of the sheath component is 2-6, and the ratio (C / S) of the degree of deformity (C) of the core component to the degree of deformity (S) of the sheath component is 0.6-1. A crimped yarn characterized by being 5.   The crimped yarn according to claim 1, wherein the sheath component is a polyamide composition containing 0.1 to 2 parts by weight of titanium oxide with respect to 100 parts by weight of polyamide.   The crimped yarn according to claim 1 or 2, wherein the sheath component is a polyamide composition containing 0.1 to 2 parts by weight of pigment with respect to 100 parts by weight of polyamide.   The crimped yarn according to any one of claims 1 to 3, wherein the sheath component is a polyamide composition containing an antioxidant and / or an ultraviolet absorber.   The crimped yarn according to any one of claims 1 to 4, wherein the crimped elongation after boiling water treatment is 10 to 40% and the boiling yield is 0 to 10%.   A carpet using the crimped yarn according to any one of claims 1 to 5.