JP2015168910A - spun yarn - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spun yarn which has improved mechanical properties, durability and humidity and thermal stability and is excellent in thermal resistance and comprises polylactic acid fibers including a polylactic acid stereo complex.SOLUTION: The spun yarn is composed of fibers consisting of a resin composition comprising a polylactic acid resin in which at least a part of a carboxyl group terminal of a polylactic acid block copolymer composed of a poly-L-lactic acid segment which contains L-lactic acid as a main component and a poly-D-lactic acid segment which contains D-lactic acid as a main component are blocked with 0.05-2 pts.mass of an isocyanurate compound expressed by general formula (1) with respect to 100 pts.mass of the polylactic acid block copolymer (at least one of R1-R3 is a glycidyl group, and the rest is a functional group such as H, 1-10C alkyl group, hydroxy group, or allyl group).

Description

  The present invention relates to a low environmental load spun yarn having high strength, high durability, drape and aesthetics, and a woven or knitted fabric using the spun yarn.

  Polylactic acid is a polymer compound that can be practically melt-molded and has biodegradable characteristics. As a result, it is decomposed in the natural environment and released as carbon dioxide or water after use. Has been developed. On the other hand, in recent years, polylactic acid itself is made from renewable resources (biomass) originating from carbon dioxide and water, so even if carbon dioxide is released after use, carbon dioxide in the global environment The property of carbon neutral that does not increase or decrease is attracting attention, and it is expected to be used as a low environmental load material.

  Furthermore, lactic acid, which is a monomer of polylactic acid, is being produced at a low cost by fermentation using microorganisms, and has been studied as an alternative material for general-purpose polymers made of petroleum plastics. However, at present, polylactic acid has lower heat resistance and durability than petroleum-based plastics. For example, when a fiber made of polylactic acid is applied to clothing, there is a problem that the surface of the fiber cloth is melted by applying a domestic iron having an intermediate temperature or higher to the fiber cloth made of polylactic acid. When applied to industrial materials, there is a problem that repeated use is difficult due to low hydrolysis resistance.

  Attempts have been made to add carbodiimide compounds and isocyanurate compounds to polylactic acid as one means for improving the heat resistance and hydrolysis resistance, which are the problems of these polylactic acids. By reacting the carboxyl group at the terminal of polylactic acid with these compounds, the terminal group of polylactic acid is blocked, and as a result, hydrolyzability is suppressed.

  On the other hand, polylactic acid stereocomplexes have attracted attention as means for improving the heat resistance of polylactic acid. In the polylactic acid stereocomplex, a stereocomplex crystal different from a conventional homocrystal is formed by mixing optically active poly-L-lactic acid and poly-D-lactic acid. Since the melting point derived from the stereocomplex crystal of polylactic acid reaches 220 ° C., which is 50 ° C. higher than the melting point 170 ° C. derived from the homocrystal of polylactic acid, an improvement in heat resistance can be expected.

  Currently, the use of polylactic acid end-capping technology and stereocomplex formation technology as described above has been attempted not only for conventional biodegradable applications but also for garment applications and industrial material applications (Patent Documents 1 to 3). 4).

  Specifically, a proposal has been made to add an isocyanurate compound containing a glycidyl group to polylactic acid to block the carboxyl group at the end of polylactic acid and reduce the carboxyl group terminal concentration (Patent Document 1). reference.). In this proposal, the fiber obtained from the end-capped polylactic acid has a high strength retention after the hydrolysis resistance test, and also has an excellent color tone as compared to the fiber end-capped with polycarbodiimide. It was. However, in this proposal, although the hydrolysis resistance of the fiber made of polylactic acid is improved, the melting point of the fiber made of polylactic acid is around 170 ° C., so that it is heat resistant for use as clothing and industrial materials. The problem remained in sex.

  On the other hand, a polylactic acid stereocomplex composed of poly-L-lactic acid and poly-D-lactic acid is prepared as a polylactic acid resin, and a carbodiimide compound is added to the polylactic acid stereocomplex, thereby improving heat resistance and resistance. There have been proposals to try to improve hydrolyzability (see Patent Document 2). However, in this proposal, the fiber made of polylactic acid end-capped with carbodiimide shows good heat resistance in a heat resistance test at a temperature of 200 ° C. However, since the carboxyl group terminal concentration is not sufficiently low, it is long-term. There remains a problem in the wet heat stability.

  On the other hand, a polylactic acid stereocomplex composed of poly-L-lactic acid and poly-D-lactic acid is prepared as a polylactic acid resin, and a carbodiimide compound is added to the polylactic acid stereocomplex, thereby improving heat resistance and resistance. There have been proposals to try to improve hydrolyzability (see Patent Document 3). However, even in this proposal, polylactic acid fibers end-capped with carbodiimide show good heat resistance in a heat resistance test at a temperature of 200 ° C. However, since the carboxyl group terminal concentration is not sufficiently low, long-term wet heat Problems remained in stability.

  In addition, in order to improve heat resistance and wet heat stability, it has also been proposed to use a core-sheath type composite fiber having a core part made of polylactic acid and a sheath part made of a petroleum polymer (see Patent Document 4). .) However, in this proposal, the strength characteristics after the wet heat environment have been improved, but there are problems such as a decrease in strength and a texture hardening due to peeling of the interface between polylactic acid and petroleum-based polymer due to heat setting at a temperature of 180 ° C. there were.

International Publication No. 2006/104092 JP 2007-23445 A JP 2002-30208 A JP 2006-247481 A

  In view of the state of the prior art described above, a new technology is required to improve the heat resistance and hydrolysis resistance of the polylactic acid stereocomplex and expand the application development to fibers.

  Specifically, for this polylactic acid stereocomplex, a polylactic acid block copolymer is drawing attention as a new stereocomplex formation method. This polylactic acid block copolymer is obtained by covalently bonding a poly-L-lactic acid segment containing L-lactic acid as a main component and a poly-D-lactic acid segment containing D-lactic acid as a main component. However, since the stereocomplex crystal formability is excellent and the melting point derived from the stereocomplex crystal is observed, it is possible to obtain a material having excellent thermal properties such as heat resistance and crystallization characteristics. However, even in this technique, although heat resistance and crystallization characteristics are excellent, hydrolysis resistance and wet heat stability are still required to be improved.

    Therefore, the present invention has been made in view of the above, and an object of the present invention is to improve aesthetics using a polylactic acid stereocomplex having improved mechanical properties, durability and wet heat stability, and also excellent heat resistance. An object of the present invention is to provide a spun yarn using fibers made of a polylactic acid resin rich in properties.

  Another object of the present invention is to provide an environment-friendly woven or knitted fabric made of the spun yarn and having excellent heat resistance and wet heat stability.

  The present invention employs the following means as a result of intensive studies to solve the above-described problems.

  That is, the spun yarn of the present invention is a carboxyl of a polylactic acid block copolymer composed of a poly-L-lactic acid segment mainly composed of L-lactic acid and a poly-D-lactic acid segment mainly composed of D-lactic acid. At least a part of the base terminal is represented by the following general formula (1) with respect to 100 parts by mass of the polylactic acid block copolymer.

Here, at least one of R1 to R3 is a glycidyl group, and the rest represents a functional group such as hydrogen, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, or an allyl group. A spun yarn composed of fibers made of a resin composition containing a polylactic acid resin blocked with 0.05 to 2 parts by mass of a nurate compound.

  In the present invention, a woven or knitted fabric can be produced by weaving or knitting the spun yarn.

  ADVANTAGE OF THE INVENTION According to this invention, the spun yarn comprised by the fiber which consists of a polylactic acid resin which was improved in mechanical physical property, durability wet heat stability, and hydrolysis resistance, and was excellent also in heat resistance is obtained.

  In addition, by using the spun yarn of the present invention, an environment-friendly woven or knitted fabric excellent in heat resistance and wet heat stability is obtained regardless of the blending partner, even though part of the yarn is composed of polylactic acid fibers. be able to.

  Next, the form for implementing this invention is demonstrated in detail.

  The spun yarn of the present invention has a carboxyl group terminal of a polylactic acid block copolymer composed of a poly-L-lactic acid segment containing L-lactic acid as a main component and a poly-D-lactic acid segment containing D-lactic acid as a main component. At least a part of which is represented by the following general formula (1) with respect to 100 parts by mass of the polylactic acid block copolymer.

Here, at least one of R1 to R3 is a glycidyl group, and the rest represents a functional group such as hydrogen, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, or an allyl group. A fiber (short fiber) made of a resin composition containing a polylactic acid resin blocked with 0.05 to 2 parts by mass of a nurate compound is used.

  The spun yarn of the present invention is made of short fibers made of a resin composition containing a polylactic acid resin as described above. However, in the present invention, short fibers made of a polylactic acid resin may be used alone. Moreover, short fibers made of polylactic acid resin and other short fibers can be blended to form a spun yarn (mixed spun yarn).

  In the present invention, other blended fibers constituting the blended yarn are specifically polyalkylene terephthalates such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polytrimethylene terephthalate (PTT). Represented polyester fiber, nylon 6, nylon 66, nylon 46, polyamide fiber represented by nylon 11 and nylon 12, acrylic fiber, polyolefin fiber represented by polypropylene and polyethylene, synthetic fiber such as fluorine fiber, rayon, Semi-synthetic fibers such as acetate, triacetate and cupra, and natural fibers such as cotton, wool, silk and hemp.

  In particular, when cotton is blended, it is preferable to use degreased and bleached cotton. Since polylactic acid has poor alkali resistance, cotton degreased and bleached before spinning is spun into cotton since the yarn strength is reduced by alkaline treatment when cotton is degreased and bleached in the post-processing of ordinary cotton blends. By combining polylactic acid in the processing, it is possible to prevent a decrease in yarn strength and a decrease in tear strength of the woven or knitted fabric.

  The blending ratio at this time is preferably 10 to 90% by mass, more preferably 20 to 80% by mass in the polylactic acid fiber blending ratio in view of the surface feeling, characteristics, and texture.

  Moreover, it is preferable that the fiber length of the fiber which comprises the mixed spun yarn at this time is 38-120 mm general according to a use or a required characteristic, and a check fiber can also be used.

  Further, the number of twists of the spun yarn of the present invention can be appropriately selected according to the use and the texture of the woven or knitted fabric (fabric), and preferably the twist coefficient K is arbitrarily set in the range of 2.5 to 6.0. Can be set. When the twisting coefficient K is less than 2.5, not only does the twist become sweet and the yarn strength becomes weak, but it also causes fluffing and may cause a decrease in physical properties. On the other hand, if the twist coefficient K exceeds 6.0, the yarn will be twisted, and the yarn will have a sharp taste and the texture will be lost. Tends to deteriorate and the surface feeling tends to deteriorate. In view of the above, the optimum twist coefficient K is preferably in the range of 3.0 to 4.5.

  Next, the polylactic acid used in the present invention is a polylactic acid block copolymer in which a segment composed of L-lactic acid units and a segment composed of D-lactic acid units are covalently bonded.

  Here, the segment consisting of L-lactic acid units is a polymer containing L-lactic acid as a main component, and means a polymer containing 70 mol% or more of L-lactic acid units. The L-lactic acid unit is preferably contained in an amount of 80 mol% or more, more preferably 90 mol% or more, particularly preferably 95 mol% or more, and 98 mol% to 100 mol%. It is the most preferable aspect to contain.

  Moreover, the segment which consists of a D-lactic acid unit is a polymer which has D-lactic acid as a main component, and means the polymer which contains 70 mol% or more of D-lactic acid units. The D-lactic acid unit is preferably contained in an amount of 80, more preferably 90 mol% or more, particularly preferably 95 mol% or more, and 98 mol% to 100 mol%. It is the most preferred embodiment.

  In the present invention, the segment comprising the L-lactic acid unit or the D-lactic acid unit is in a range not impairing the performance of the polylactic acid block copolymer and the polylactic acid resin composition containing the polylactic acid block copolymer. Component units can be included.

  Examples of the component unit other than the L-lactic acid unit or the D-lactic acid unit include polyvalent carboxylic acid, polyhydric alcohol, hydroxycarboxylic acid, lactone, and the like. Specifically, succinic acid, adipic acid, sebacic acid Polycarboxylic acids such as fumaric acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid or derivatives thereof, ethylene glycol, propylene glycol, Add ethylene oxide or propylene oxide to butanediol, pentanediol, hexanediol, octanediol, neopentylglycol, glycerin, trimethylolpropane, pentaerythritol, trimethylolpropane or pentaerythritol Polyhydric alcohols, aromatic polyhydric alcohols obtained by addition reaction of bisphenol with ethylene oxide, polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol or derivatives thereof, glycolic acid, 3-hydroxybutyric acid, 4 Hydroxycarboxylic acids such as hydroxybutyric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, and glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, Examples include pivalolactone and lactones such as δ-valerolactone.

  As other component units, polyvalent carboxylic acid anhydrides, polyvalent isocyanates, polyhydric alcohols and polyvalent epoxy compounds are preferred, and polyvalent carboxylic acid anhydrides, polyvalent isocyanates and polyvalent epoxy compounds are particularly preferably used. These may be used alone or in combination of two or more.

  The amount of the compound composed of other component units is preferably 0.01 parts by mass or more and 20 parts by mass or less, more preferably 100 parts by mass in total of poly-L-lactic acid and poly-D-lactic acid. Is 0.1 to 10 parts by mass. The effect of using the compound which consists of another component unit can be exhibited effectively as the addition amount of the compound which consists of another component unit is in the said preferable range.

  Since the polylactic acid block copolymer used in the present invention has a melting point based on stereocomplex crystals in the range of 190 to 230 ° C. due to stereocomplex formation, it is superior in heat resistance compared to polylactic acid homopolymer. The preferable range of the melting point derived from the stereocomplex crystal is 200 ° C. to 230 ° C., a temperature range of 205 ° C. to 230 ° C. is more preferable, and a temperature range of 210 ° C. to 230 ° C. is a particularly preferable embodiment. Moreover, in the temperature range of 150 degreeC-185 degreeC, it may have a small melting peak based on a poly-L-lactic acid single crystal and a poly-D-lactic acid single crystal.

  The polylactic acid block copolymer used in the present invention preferably has a stereocomplex formation rate (Sc) in the range of 80 to 100%, more preferably in the range of 85 to 100%, from the viewpoint of heat resistance. It is especially preferable that it is 90 to 100%.

Here, the stereocomplex formation rate (Sc) is the ratio of the stereocomplex crystals in all the crystals in polylactic acid. Specifically, poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when heated from a temperature of 30 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min with a differential scanning calorimeter (DSC). Assuming that the amount of heat based on crystal melting is ΔHl and the amount of heat based on crystal melting of the stereocomplex crystal is ΔHh, it can be calculated by the following equation (1).
Sc = ΔHh / (ΔHl + ΔHh) × 100 (1)
In the present invention, the polylactic acid block copolymer preferably has a temperature-falling crystallization temperature (Tc) of 130 ° C. or higher in terms of excellent moldability and heat resistance. Here, the temperature drop crystallization temperature (Tc) of the molded body is a temperature of 250 ° C. after the temperature is raised from 30 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min by a differential scanning calorimeter (DSC). This is a crystallization temperature derived from polylactic acid crystals measured when the temperature is maintained at a constant temperature for 3 minutes and the temperature is lowered at a cooling rate of 20 ° C./min. From the viewpoint of heat resistance and transparency, the crystallization temperature (Tc) is preferably 130 ° C. or higher, more preferably 132 ° C. or higher, and particularly preferably 135 ° C. or higher.

  The weight average molecular weight of the polylactic acid block copolymer used in the present invention is preferably 100,000 or more and less than 300,000 in terms of mechanical properties. The weight average molecular weight is more preferably 120,000 or more and less than 280,000, still more preferably 130,000 or more and less than 270,000, and particularly preferably 140,000 or more and less than 260,000 in terms of moldability and mechanical properties. It is.

  Moreover, the dispersity of the polylactic acid block copolymer is preferably in the range of 1.5 to 3.0 in terms of mechanical properties. The range of the dispersity is more preferably 1.8 to 2.7, and 2.0 to 2.4 is a particularly preferable embodiment in terms of moldability and mechanical properties.

  In the present invention, the weight average molecular weight and dispersity are values in terms of standard polymethyl methacrylate as measured by gel permeation chromatography (GPC) using hexafluoroisopropanol or chloroform as a solvent.

  In the present invention, the average chain length of the polylactic acid block copolymer is preferably 20 or more, more preferably 25 or more, and particularly preferably 30 or more in terms of mechanical properties of the molded product. is there.

The average chain length of the polylactic acid block copolymer was determined by ¹³ C-NMR measurement, and among the peaks of carbon attributed to carbonyl carbon, (a), 169 When the integrated value of the peak existing in the vicinity of .8 to 170.0 ppm is (b), it can be calculated by the following formula (2).
Average chain length = (a) / (b) (2)
In the present invention, from the viewpoint of obtaining a polylactic acid block copolymer that easily forms a high-melting-point polylactic acid stereocomplex, a segment composed of L-lactic acid units contained per molecule of the polylactic acid block copolymer and D -The total number of segments composed of lactic acid units is preferably 3 or more, more preferably 5 or more, and particularly preferably 7 or more.

  In the present invention, the total mass ratio of the segment consisting of the L-lactic acid unit and the segment consisting of the D-lactic acid unit is preferably 90:10 to 10:90, more preferably 80:20 to 20: 80, particularly preferably 75:25 to 60:40 or 40:60 to 25:75. When the total mass ratio of the segment consisting of the L-lactic acid unit and the segment consisting of the D-lactic acid unit is within the above preferred range, a polylactic acid stereocomplex can be easily formed. The rise in the melting point of the coalescence becomes sufficiently large.

  In the present invention, the weight average molecular weight of poly-L-lactic acid and poly-D-lactic acid used for obtaining a polylactic acid block copolymer is poly-L-lactic acid from the viewpoint of increasing the stereocomplex formation rate. It is preferable that the weight average molecular weight of either one of poly-D-lactic acid is 30,000 to 100,000 or less and the other weight average molecular weight is 10,000 to 30,000 or less. More preferably, one weight average molecular weight is 35,000 to 90,000, and the other weight average molecular weight is 10,000 to 25,000. Particularly preferably, one weight average molecular weight is 40,000 to 80,000, and the other weight average molecular weight is 10,000 to 20,000.

  Further, the ratio of the weight average molecular weight of poly-L-lactic acid used in the above mixing to the weight average molecular weight of poly-D-lactic acid (weight average molecular weight of poly-L-lactic acid / weight of poly-D-lactic acid) The average molecular weight is preferably from 2 to less than 10, more preferably from 3 to less than 10, and particularly preferably from 4 to less than 10 from the viewpoint of increasing the stereocomplex formation rate.

  As a method for producing the polylactic acid block copolymer, a general method for producing polylactic acid can be used. Specifically, ring-opening polymerization is performed in the presence of a catalyst on either a cyclic dimer L-lactide or D-lactide produced from raw lactic acid, and lactide, which is an optical isomer of polylactic acid, is further obtained. Addition and ring-opening polymerization to obtain a polylactic acid block copolymer, a lactide method (Production method 1), poly-L-lactic acid and poly-D-lactic acid by direct polymerization of the raw material or ring-opening polymerization via lactide And then mixing the obtained poly-L-lactic acid and poly-D-lactic acid, followed by solid-phase polymerization to obtain a polylactic acid block copolymer (Production Method 2), poly-L-lactic acid and Poly-D-lactic acid is obtained by subjecting an L-lactic acid unit segment and a D-lactic acid unit segment to a transesterification reaction by performing melt-kneading for a long time at a temperature higher than the melting end temperature of the component having a higher melting point. Lactic acid A method of obtaining a lock copolymer (Production method 3), and mixing a polyfunctional compound with poly-L-lactic acid and poly-D-lactic acid to react with each other, thereby producing poly-L-lactic acid and poly-D-lactic acid There is a method of producing a polylactic acid block copolymer by covalently bonding a polyfunctional compound (Production Method 4).

  Any of the above-described methods may be used for the production method of the polylactic acid block copolymer, but the method of solid-phase polymerization after mixing poly-L-lactic acid and poly-D-lactic acid is known as a polylactic acid block copolymer. The total number of segments consisting of L-lactic acid units and segments consisting of D-lactic acid units contained in one molecule of the polymer is 3 or more, and as a result, polylactic acid block copolymer having both heat resistance, crystallinity and mechanical properties. This is a preferable method in that a coalescence can be obtained.

  Here, poly-L-lactic acid is a polymer containing L-lactic acid as a main component and containing 70 mol% or more of L-lactic acid units as described above. It is preferable to contain 80 mol% or more of L-lactic acid units, more preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 98 mol% or more. This is a preferred embodiment.

  Moreover, poly-D-lactic acid is a polymer which has D-lactic acid as a main component as mentioned above, and refers to a polymer containing 70 mol% or more of D-lactic acid units. It is preferable to contain 80 mol% or more of D-lactic acid units, more preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 98 mol% or more. This is a preferred embodiment.

  Next, the polymerization method of the various polylactic acid block copolymers will be described in detail.

  First, as a method for producing a polylactic acid block copolymer by ring-opening polymerization (Production Method 1), for example, one of L-lactide and D-lactide is subjected to ring-opening polymerization in the presence of a catalyst, and then the other optical An example is a method of obtaining a polylactic acid block copolymer by performing ring-opening polymerization by adding lactide which is an isomer.

  The ratio of the weight average molecular weight of the segment consisting of L-lactic acid units and the weight average molecular weight of the segments consisting of D-lactic acid units contained per molecule of the polylactic acid block copolymer obtained by ring-opening polymerization is the heat resistance and the molded product From the viewpoint of transparency, it is preferably 2 or more and less than 30, more preferably 3 or more and less than 20, and particularly preferably 5 or more and less than 15. Here, the ratio of the weight average molecular weight of the segment comprising L-lactic acid units to the segment weight average molecular weight comprising the D-lactic acid units is determined by the ratio of L-lactide and D-lactide used when polymerizing the polylactic acid block copolymer. Can be controlled by the mass ratio.

  From the viewpoint of improving heat resistance and crystallinity, the total number of segments consisting of L-lactic acid units and segments consisting of D-lactic acid units contained per molecule of polylactic acid block copolymer obtained by ring-opening polymerization is improved. It is preferably 3 or more, more preferably 5 or more, and particularly preferably 7 or more. The upper limit of the total number of segments is about 50 segments.

  The weight average molecular weight per segment is preferably 2,000 to 50,000, more preferably 4,000 to 45,000, and particularly preferably 5,000 to 40,000.

  The optical purity of L-lactide and D-lactide used in the ring-opening polymerization method is preferably 90% ee or more, more preferably from the viewpoint that the crystallinity and melting point of the polylactic acid block copolymer can be improved. It is 95% ee or more, and particularly preferably 98% ee or more.

  When obtaining a polylactic acid block copolymer by the ring-opening polymerization method, the water content in the reaction system is 4 mol% or less with respect to the total amount of L-lactide and D-lactide from the viewpoint of obtaining a high molecular weight product. Is preferable, more preferably 2 mol% or less, and particularly preferably 0.5 mol% or less. Here, the water content is a value measured by a coulometric titration method using the Karl Fischer method.

  Next, a method (Production Method 2) for obtaining a polylactic acid block copolymer by solid phase polymerization after mixing poly-L-lactic acid and poly-D-lactic acid will be described. In this production method 2, any of a ring-opening polymerization method and a direct polymerization method can be used as a method for producing poly-L-lactic acid and poly-D-lactic acid.

  In the case of producing a polylactic acid block copolymer by solid phase polymerization after mixing poly-L-lactic acid and poly-D-lactic acid, the viewpoint that the weight average molecular weight and stereocomplex formation rate after solid phase polymerization are increased From any one of poly-L-lactic acid and poly-D-lactic acid, the weight average molecular weight is 60,000 to 300,000 or less, and the other weight average molecular weight is 10,000 to 50,000 or less. Preferably there is. More preferably, one weight average molecular weight is 100,000 to 270,000, and the other weight average molecular weight is 15,000 to 45,000. Particularly preferably, one weight average molecular weight is 150,000 to 240,000 and the other weight average molecular weight is 20,000 to 40,000. The combination of the weight average molecular weights of poly-L-lactic acid and poly-D-lactic acid is preferably appropriately selected so that the weight average molecular weight after mixing is 90,000 or more.

  In addition, the poly-L-lactic acid and poly-D-lactic acid used in the present invention each have a mass ratio of 2 or more and less than 30 in terms of the higher weight average molecular weight and the lower weight average molecular weight. More preferably, it is 3 or more and less than 20, and most preferably 5 or more and less than 15. The combination of the weight average molecular weights of poly-L-lactic acid and poly-D-lactic acid is preferably selected as appropriate so that the weight average molecular weight after mixing is 90,000 or more.

  The amount of lactide and oligomer contained in poly-L-lactic acid or poly-D-lactic acid is preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 1% by mass or less. is there. The amount of lactide and oligomer are preferably small. The amount of lactic acid contained in poly-L-lactic acid or poly-D-lactic acid is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less. It is. The amount of lactic acid is also preferably small.

  As for the acid value of poly-L-lactic acid or poly-D-lactic acid to be mixed, it is preferable that either one of poly-L-lactic acid or poly-D-lactic acid has an acid value of 100 eq / ton or less, More preferably, it is 50 eq / ton or less, More preferably, it is 30 eq / ton or less, Especially preferably, it is 15 eq / ton or less. The other acid value of poly-L-lactic acid or poly-D-lactic acid to be mixed is preferably 600 eq / ton or less, more preferably 300 eq / ton or less, and further preferably 150 eq / ton. Or less, particularly preferably 100 eq / ton or less. The lower limit of the acid value is preferably 1 eq / ton.

  Regarding the method for producing poly-L-lactic acid or poly-D-lactic acid using the ring-opening polymerization method, from the viewpoint of obtaining a high molecular weight product, the amount of water in the reaction system is L-lactide and D-lactide. The total amount is preferably 4 mol% or less, more preferably 2 mol% or less, and particularly preferably 0.5 mol% or less. Here, the water content is a value measured by a coulometric titration method using the Karl Fischer method. In order to increase the reactivity, the lower limit of the amount of water in the reaction system is preferably 0.1 mol%.

<Isocyanurate compound>
In the present invention, the carboxyl group terminal of the polylactic acid block copolymer is blocked to improve hydrolysis resistance and wet heat stability, and the polylactic acid resin composition is a good production that does not generate irritating odors such as chlorine compounds. In order to produce in an environment, it is necessary to include a glycidyl-modified compound having 1 to 3 functional groups having an isocyanurate compound represented by the following general formula (1) as a basic skeleton.

  Here, among the isocyanurate compounds represented by the general formula (1), at least one of R1 to R3 is a glycidyl group. Further, isocyanurate compounds having different addition numbers of glycidyl groups may be added to the polylactic acid block copolymer. In addition, among R1 to R3, as a functional group other than the glycidyl group, hydrogen or an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, and an allyl group are selected.

  Here, the number of carbon atoms in the alkyl group is preferably as small as possible, and preferably 1 to 5 carbon atoms. Among them, diallyl monoglycidyl isocyanurate (hereinafter abbreviated as DAMGIC), monoallyl glycidyl isocyanurate (hereinafter abbreviated as MADGIC), and triglycidyl isocyanurate (hereinafter abbreviated as TGIC). Is preferably used because of its high melting point and excellent heat resistance.

  Furthermore, when adding an isocyanurate compound, a reaction catalyst can be added to promote the reaction between the polylactic acid block copolymer and the isocyanurate compound.

  Examples of the reaction catalyst include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, stearin. Sodium phosphate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, sodium phenyl borohydride, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, Dilithium hydrogen phosphate, disodium salt of bisphenol A, dipotassium salt, dilithium salt, phenol sodium salt, potassium salt, lithium salt, cesium salt and other alkali metal compounds, calcium hydroxide, water Oxidation Alkaline earths such as lithium, magnesium hydroxide, strontium hydroxide, calcium bicarbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, magnesium stearate, strontium stearate Metal compounds, triethylamine, tributylamine, trihexylamine, triamylamine, triethanolamine, dimethylaminoethanol, triethylenediamine, dimethylphenylamine, dimethylbenzylamine, 2- (dimethylaminomethyl) phenol, dimethylaniline, pyridine, picoline , Tertiary amines such as 1,8-diazabicyclo [5.4.0] -7-undecene, 2-methylimidazole, 2- Imidazole compounds such as tilimidazole, 2-isopropylimidazole, 2-ethyl-4-methylimidazole, 4-phenyl-2-methylimidazole, tetramethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium bromide, trimethylbenzylammonium chloride, triethyl Quaternary ammonium salts such as benzylammonium chloride, tripropylbenzylammonium chloride, N-methylpyridinium chloride, phosphine compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, tetramethylphosphonium bromide, tetrabutylphosphonium bromide, Tetraphenylphosphonium bromide, Phosphonium salts such as tritylphenylphosphonium bromide, triphenylbenzylphosphonium bromide, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl Phosphate esters such as diphenyl phosphate, octyl diphenyl phosphate, tri (p-hydroxy) phenyl phosphate, tri (p-methoxy) phenyl phosphate, oxalic acid, p-toluenesulfonic acid, dinonylnaphthalenedisulfonic acid, dodecylbenzenesulfonic acid, etc. Organic acids, such as boron trifluoride, aluminum tetrachloride, titanium tetrachloride, and tin tetrachloride Chairs acid and the like, which may be used alone or in combination of two or more.

  The addition amount of the reaction catalyst is preferably 0.001 part by mass or more and 0.5 part by mass or less with respect to 100 parts by mass of the polylactic acid block copolymer. When the catalyst amount is within the above preferred range, the effect of shortening the polymerization time can be obtained, while the molecular weight of the finally obtained polylactic acid resin composition can be increased.

  In the present invention, the polylactic acid fiber needs to be capped at least at a part of the carboxyl group terminals in that it is excellent in hydrolysis resistance and wet heat stability. Here, the terminal carboxyl group concentration is preferably as low as possible, and is preferably 10 equivalents / ton or less. More preferably, it is 7 equivalent / ton or less, More preferably, it is 5 equivalent / ton or less. On the other hand, the lower the equivalent, the worse the reactivity, so the lower limit of the terminal carboxyl group concentration is preferably 0.1 equivalent / ton.

  Specifically, in the polylactic acid resin used in the present invention, at least a part of the carboxyl group terminal of the polylactic acid block copolymer is the isocyanurate compound with respect to 100 parts by mass of the polylactic acid block copolymer. It is a polylactic acid resin blocked with 0.05 to 2 parts by mass. The ratio of the isocyanurate compound is more preferably 0.3 to 1.5 parts by mass, and still more preferably 0.6 to 1.2 parts by mass.

  The isocyanurate compound is added at the time of melt-kneading with the polylactic acid block copolymer to block the carboxyl group terminal.

  In the present invention, a conventionally known melt spinning method can be used as a manufacturing method for molding and processing a resin composition containing a polylactic acid resin into a fiber. In terms of increasing the degree of orientation, it is preferable to employ a high-speed spinning process and a stretching process. By stretching fibers made of a resin composition containing a polylactic acid resin, the fibers are fully oriented and mechanical properties are improved, and at the same time, crystallization progresses sufficiently by heat treatment. It becomes possible to obtain excellent fibers.

  In the present invention, the spinning speed at the time of spinning a resin composition containing a polylactic acid resin is preferably 500 to 10,000 m / min, whereby molecular orientation occurs, and the process passability in the subsequent stretching process is improved. Can be increased. The spinning speed in the present invention refers to the peripheral speed of the first godet roll for taking up the yarn. Further, in order to perform drawing simultaneous false twisting and the like, further molecular orientation is required, so the spinning speed is more preferably 2,000 m / min or more, more preferably 3,000 m / min or more, particularly preferably. 4,000 m / min or more. On the other hand, considering the process stability in the spinning process, the spinning speed is preferably 7,000 m / min or less. The undrawn yarn obtained in this high-speed spinning process has a high degree of orientation, becomes a precursor that can form a stereocomplex crystal efficiently, and also has excellent mechanical strength, so it has excellent processability in the drawing process. Show properties.

  On the other hand, the drawing process of the undrawn yarn comprising the resin composition containing the polylactic acid resin obtained above may be, for example, a process of preheating, drawing, and heat setting between a hot roller and a hot roller, or a cold roller. / Polylactic acid may be produced by hot plate / heat roller, but polylactic acid is weak in interaction between molecular chains due to its molecular structure and often has poor wear resistance. Is a more preferred embodiment. Since the high-speed-spun undrawn yarn obtained above has a high degree of orientation, the preheating temperature (for example, the temperature of the first hot roller or hot plate) in the drawing step is preferably selected as appropriate at a temperature of 80 to 140 ° C. can do.

  Moreover, about the heat setting process in an extending process, by setting it higher than the said preheating temperature, crystallization of the fiber obtained is accelerated | stimulated and heat resistance by dimensional stability and stereocomplex crystal formation is provided to a fiber. Can do. For this reason, it is preferable that the heat setting temperature is equal to or higher than the preheating temperature and is in a temperature range of 130 to 200 ° C.

  In the present invention, in a fiber drawing false twisting process comprising a resin composition containing a polylactic acid resin, a conventionally known drawing false twisting process such as an outdraw process or an indow process can be appropriately selected. Since the Indro process can simplify the manufacturing equipment, the fiber can be manufactured at low cost. In addition, as a twisted body in the drawing false twisting process, pins, belts, disks, and the like can be used. However, if a belt or a disk is used, high-speed drawing false twisting is possible. The production amount can be increased, and as a result, the fiber can be manufactured at low cost. In addition, the heater of the drawing false twister can adopt either a contact type or a non-contact type, but in the case of a non-contact type, the wear of the fiber made of the polylactic acid resin composition should be reduced. Can do. Furthermore, the temperature of the heater is preferably selected as appropriate in a temperature range of 100 to 200 ° C. from the viewpoint of imparting mechanical strength, dimensional stability and heat resistance of the false twisted yarn. Within this temperature range, the fiber obtained in the drawing false twisting process can be manufactured stably without yarn breakage, and it has excellent mechanical strength, dimensional stability, and heat resistance sufficiently oriented and crystallized. It can be a fiber.

  Furthermore, in order to improve the dimensional stability of the drawn false twisted yarn, it is also preferable to apply a relaxing heat treatment after the drawn false twist. The fiber made of the resin composition containing the polylactic acid resin obtained by the above method not only has excellent mechanical properties and dimensional stability, but also has a sufficient number of stereocomplex crystals. Excellent in properties and can be dyed at high temperature.

  The single fiber fineness of the fiber made of the polylactic acid resin of the invention is preferably 0.6 dtex or more and 7.0 dtex or less from a practical viewpoint. The single fiber fineness is more preferably 0.8 dtex to 4.0 dtex from the viewpoint of passing through the spinning process and quality.

  When the single fiber fineness exceeds 7.0 dtex, even if twisted to make a spun yarn, the bending rigidity of the single yarn (spun yarn) increases and appears on the surface of the spun yarn as fluff. In addition to lowering, when the fluff tip that protrudes comes into contact with the skin, a tingling sensation is generated and uncomfortable feeling is generated, which tends to be impractical for clothing. On the other hand, if the single fiber fineness is less than 0.6 dtex, the single fibers are entangled with each other at the stage of the spinning process, and it becomes easy to form a nep or slab, which is not preferable in terms of quality appearance.

  The fiber length is also an important factor for realizing comfortable wearing. When using short fibers with a single fiber fineness of 3.9 dtex, the fiber length used should be 38 mm or more from the viewpoint of aspect ratio. When fibers shorter than 38 mm are used, fluffing is increased when spun yarn is used, and a flickering irritation tends to occur when the fluff tip comes into contact with the skin.

An aspect ratio required for forming fibers is a guideline of 1,000 or more. When the aspect ratio is less than 1,000, it is difficult to form a spun yarn. The aspect ratio shown here is calculated by the following calculation formula.
Fiber aspect ratio = fiber length (mm) / fiber diameter (φmm).

  The spun yarn of the present invention preferably has a spinning count in the range of 10 s to 80 s, and more preferably in the range of 20 to 60 s, from the texture and good appearance when the fiber fabric is made.

Similarly, regarding the number of twists added to the spun yarn, it is preferable that the twist coefficient K is in the range of 2.5 to 6.0 in consideration of texture and appearance. When in the sweet twisted state, a lot of fluff is exposed on the surface of the yarn, and pilling, so-called fluff is likely to occur.On the contrary, when it is in the strong twisted state, the occurrence of snare on the yarn and the sharpness is expressed in the texture, It is preferable to set according to the application. The spinning count shown here can be calculated by the following formula.
・ Spinning count = √Ne count × twisting coefficient (K) = t / 2.54 cm
Furthermore, when the spun yarn of the present invention is used, it is preferable to use a woven fabric rather than a knitted product because there is a pilling problem peculiar to the spun yarn in the weaving and knitting process.

  The mixing ratio of the polylactic acid fiber used in the present invention is preferably 10% by mass to 90% by mass, and most preferably 20% by mass to 80% by mass with respect to the total mass of the knitted fabric. It is.

  When the blending ratio of polylactic acid fibers is in the above range, the degradation yarn strength of the polylactic acid fibers after dyeing processing, the bursting strength and tearing strength of the knitted fabric can be satisfied, and the iron heat resistance and texture can be improved. Can do. It is preferable that other fibers to be mixed are used after being dyed in a chromatic color in the same manner as the polylactic acid fiber with an appropriate dye. Examples of other fibers include wool, silk, rayon, acetate, or fibers such as polyester, nylon, acrylic, vinylon, polyolefin, and polyurethane. Cellulose fibers such as cotton, hemp, rayon, and tencel are preferably used.

  In addition to various combinations with fiber structures composed of other fibers, mixed modes include mixed yarns with other fibers, composite false twisted yarns, mixed spun yarns, long and short composite yarns, fluid processed yarns, covering yarns, and twisted yarns. Examples thereof include union knitting, union knitting, pile knitted knitted fabric, mixed cotton stuffed cotton, mixed non-woven fabric of long fibers and short fibers, and felt.

  The use of spun yarn using short fibers made of the resin composition containing the polylactic acid resin of the present invention, and blended spun yarn by mixing with other fibers can be used for clothing that requires hydrolysis resistance, such as outdoor wear. And sportswear such as golf wear, athletic wear, ski wear, snowboard wear and their pants, casual wear such as blousons, and outerwear for ladies and gentlemen such as coats, winter clothes and rainwear.

  In addition, applications that require excellent durability and moisture aging characteristics over a long period of use include uniforms, comforters and mattresses, skin comforters, kotatsu comforters, cushions, baby comforters, blankets, etc., pillows, cushions, etc. There are uses for bedding materials such as side covers and covers, mattresses and bed pads, hospital sheets, medical sheets, hotel sheets and baby sheets, as well as covers for sleeping bags, cradle and strollers, etc. be able to.

  Moreover, it can be used suitably also for interior materials for automobiles, and among them, it is most suitable to be used for carpets for automobiles and nonwoven fabrics for ceiling materials that require high hydrolysis resistance and moisture aging characteristics.

  The uses of the spun yarn and the mixed spun yarn made of the polylactic acid resin of the present invention are not limited to these uses. For example, as other uses, a herbicidal sheet for agriculture, a waterproof sheet for building materials, and a fishing line. , Fishing nets, laver nets, vegetation protection nonwoven fabrics, civil engineering nets, sandbags, seedling pots, agricultural materials and draining bags.

  In the spun yarn of the present invention, the strength retention, which is an index of hydrolysis resistance, is preferably 60 to 99%, more preferably 70 to 99%, and still more preferably 80 to 99%. Especially preferably, it is 85 to 99%. The strength retention is based on the strength ratio before and after the heat treatment when the multifilament made of the polylactic acid resin composition is sealed in a sealed container and immersed in water, and the sealed container is heated at a temperature of 130 ° C. for 40 minutes. It is a calculated value.

  Next, although an example is given and the spun yarn using the short fiber which consists of polylactic acid resin of the present invention is explained, the present invention is not limited by these examples. Here, the part in an Example shows a mass part. Moreover, the measuring methods, such as a physical property, are as follows. All measurements are displayed as average values at 10 points.

(1) Weight average molecular weight:
The weight average molecular weight and dispersity are values in terms of standard polymethyl methacrylate measured by gel permeation chromatography (GPC). For GPC measurement, a differential refractometer WATERS410 manufactured by WATERS is used as a detector, a MODEL510 manufactured by WATERS is used as a pump, and “Shodex” (registered trademark) GPC HFIP-806M and “Shodex” manufactured by Showa Denko KK are used as a column. "(Registered trademark) GPC HFIP-LG was used in series. The measurement conditions were a flow rate of 0.5 mL / min. In the measurement, hexafluoroisopropanol was used as a solvent, and 0.1 mL of a solution having a sample concentration of 1 mg / mL was injected.

(2) Thermal characteristics:
The melting point and heat of fusion were measured by a differential scanning calorimeter (DSC) manufactured by PerkinElmer. The measurement conditions are 5 mg of the sample, a nitrogen atmosphere, and a heating rate of 20 ° C./min.

  Here, the melting point refers to the peak top temperature in the crystal melting peak, and the melting end temperature refers to the peak end temperature in the crystal melting peak. In the obtained results, those whose melting point was confirmed to be 190 ° C. or more and less than 250 ° C. were judged as polylactic acid stereocomplexes formed, and those whose melting point was confirmed to be 150 ° C. or more and less than 190 ° C. It was judged that a polylactic acid stereocomplex was not formed. Here, melting | fusing point of the polylactic acid resin composition shown shows melting | fusing point measured when it heats up from 30 degreeC to the temperature of 250 degreeC at the temperature increase rate of 20 degree-C / min at the time of 2nd temperature increase. The stereo complex crystal-derived heat of fusion (ΔHmsc) is calculated from the peak area of the stereo complex crystal melting peak when measured by the above method.

(3) Stereo complex formation rate (Sc):
The stereocomplex formation rate (Sc) of the polylactic acid resin composition was calculated from the following formula (1).
Sc = ΔHh / (ΔHl + ΔHh) × 100 (1)
Here, ΔHl indicates the amount of heat based on crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal appearing at a temperature of 150 ° C. or more and less than 190 ° C., and ΔHh is stereo appearing at a temperature of 190 ° C. or more and less than 250 ° C. The amount of heat based on the crystal melting of the complex crystal is shown.

  Moreover, the stereocomplex formation rate (Sc) of the polylactic acid resin composition in an Example is computed from the crystal melting peak measured at the time of the 2nd temperature increase of a differential scanning calorimeter (DSC).

(4) Carboxyl group terminal concentration:
The carboxyl group terminal concentration of the polylactic acid resin composition was calculated by dissolving the pellet of the polylactic acid resin composition in an o-cresol / chloroform mixed solution and then titrating with a 0.02 N ethanolic potassium hydroxide solution. .

(5) Weight average molecular weight retention:
The molecular weight retention of the polylactic acid resin composition was determined by subjecting the pellets of the polylactic acid resin composition to a wet heat treatment for 100 hours at a temperature of 60 ° C. and 95% RH, and the weight average molecular weight (Mw1) before the wet heat treatment and the wet heat treatment. It computed from following weight average molecular weight (Mw2) according to following formula (3).
Weight average molecular weight retention rate (%) = Mw2 / Mw1 × 100 (3).

(6) Strength of drawn yarn (multifilament):
The strength of the drawn yarn (multifilament) made of the resin composition containing the polylactic acid resin of the present invention is JIS L1013 (chemical fiber filament yarn test method, 1998) using Tensilon UCT-100 manufactured by Orientec Corporation. ) Under constant speed stretching conditions (grab interval: 20 cm, stretching speed 20 cm / min).

(7) Strength retention of drawn yarn (multifilament):
Stretched yarn comprising a resin composition containing the polylactic acid resin of the present invention (the strength of the multifilament was measured by the following procedure. Bobbin so as not to shrink 1 g of the drawn yarn comprising the resin composition containing the polylactic acid resin. Wrapped in a container that can be sealed together with 300 ml of water, heated at a rate of temperature rise of 4 ° C./min so that the water temperature in the vessel becomes 130 ° C., held at a temperature of 130 ° C. for 40 minutes, and then cooled down It was cooled at a rate of 4 ° C./min.When the water temperature in the container became 50 ° C. or less, the sample was taken out and washed with water, and from the tensile strength (T1) before heat treatment and the tensile strength (T2) after heat treatment, The strength retention was calculated according to equation (4).
Strength retention (%) = T2 / T1 × 100 (4).

(8) Heat resistance of fabric iron after jungle test:
The fabric made of the polylactic acid resin composition obtained in the following examples was left to stand for 1 week in an environment of 70 ° C. × 95% RH, and then a household iron set to a medium temperature (surface temperature of 170 ° C.) 10 Press for 2 seconds, ◎ if there is no change, ◯ if there is a slight cure, △ if there is a clear cure, x if the cure is noticeable or melted, 4 stages The iron heat resistance evaluation was performed with ◎ and ○ as acceptable.

[Example 1]
In a reaction vessel equipped with a stirrer and a reflux device, 50 parts of a 90% strength L-lactic acid aqueous solution was placed, the temperature was set to 150 ° C., and the pressure was gradually reduced to 3.5 hours while distilling off the water. Reacted. Thereafter, the pressure was returned to normal pressure in a nitrogen atmosphere, 0.02 part of tin (II) acetate was added, and a polymerization reaction was performed for 7 hours while gradually reducing the pressure to 13 Pa at a temperature of 170 ° C. Subsequently, the obtained poly-L-lactic acid was subjected to crystallization treatment at a temperature of 110 ° C. for 1 hour in a nitrogen atmosphere, and then at a temperature of 140 ° C. for 3 hours and a temperature of 150 ° C. under a pressure of 60 Pa. Solid-state polymerization was performed for 3 hours at a temperature of 160 ° C. for 18 hours to obtain poly-L-lactic acid (PLA1). The obtained PLA1 had a weight average molecular weight of 200,000, a dispersity of 1.7, and a melting point of 170 ° C.

  Next, 50 parts of a 90% strength aqueous D-lactic acid solution was placed in a reaction vessel equipped with a stirrer and a reflux device, and the temperature was set to 150 ° C. The reaction was allowed for 5 hours. Thereafter, the pressure was returned to normal pressure in a nitrogen atmosphere, 0.02 part of tin (II) acetate was added, and a polymerization reaction was performed for 7 hours while gradually reducing the pressure to 13 Pa at a temperature of 170 ° C. Subsequently, the obtained poly-D-lactic acid was subjected to crystallization treatment at a temperature of 110 ° C. for 1 hour under a nitrogen atmosphere, and then at a temperature of 140 ° C. for 3 hours and a temperature of 150 ° C. under a pressure of 60 Pa. Solid phase polymerization was performed for 3 hours at a temperature of 160 ° C. to obtain poly-D-lactic acid (PDA1). The obtained PDA1 had a weight average molecular weight of 40,000, a dispersity of 1.5, and a melting point of 156 ° C.

  The PLA1 and PDA1 obtained by the above method were crystallized for 2 hours at a temperature of 110 ° C. in a nitrogen atmosphere before mixing. Subsequently, 50 parts by mass of PLA1 subjected to crystallization treatment is added from the resin supply port of the twin-screw extruder, and 50 parts by mass of PDA1 is added from the side supply port provided at the portion of L / D = 30 described later. Thus, melt kneading was performed. Here, the twin-screw extruder has a plasticized portion set at a temperature of 190 ° C. at a portion of L / D = 10 from the resin supply port, and is provided with a kneading disk at a portion of L / D = 30 to apply shear. It has a structure that can be mixed under shearing as a possible screw. Using a twin screw extruder, PLA1 and PDA1 were melt-kneaded at a kneading temperature of 210 ° C. under reduced pressure to obtain a polylactic acid stereocomplex. The obtained polylactic acid stereocomplex had a weight average molecular weight of 110,000, a dispersity of 2.7, a melting point of 211 ° C., and a stereocomplex formation rate of 100%.

  Next, with respect to 100 parts of the polylactic acid stereocomplex obtained above, an isocyanurate compound (triglycidyl isocyanurate (“TEPIC” (registered trademark) -S, manufactured by Nissan Chemical Industries, epoxy equivalent 100 g / mol)) The mixture was mixed at a rate of 0.1 part, adjusted to a carboxyl group terminal concentration of 17 eq / ton, and melt-kneaded using a twin screw extruder having 17 vents. A plasticized part set at a temperature of 225 ° C. from the mouth to a part at L / D = 10, and a structure that can be mixed under shearing as a screw that can be sheared with a kneading disk at the part at L / D = 30. The resin composition comprising the polylactic acid resin pelletized by melt-kneading at a kneading temperature of 220 ° C. under reduced pressure using this twin-screw extruder. To obtain poly lactic acid chip.

  Separately, the polylactic acid chip obtained in Example 1 was melt-spun using a spinneret to produce a tow-like fine-fineness polylactic acid fiber bundle with a single fiber fineness of 3.0 dtex, and this was made into a fiber length of 38 mm. The raw cotton was obtained by cutting into short fibers.

  The above-obtained 65% by mass of raw cotton made of short fibers made of polylactic acid resin having a single fiber fineness of 3.0 dtex and a fiber length of 38 mm and 35% by mass of absorbent cotton were mixed using an OHARA cotton blender. Thereafter, the blended fiber was made into a card sliver using a card machine manufactured by Ishikawa Seisakusho and passed twice through a drawing machine manufactured by Ishikawa Seisakusho to produce a sliver of 2.95 g / 100 cm. Further, a roving machine (fiber bundle A) of 0.47 g / 100 cm was produced through a spinning machine manufactured by Toyota Industries Corporation.

  After that, it was spun at a draft of 32 times using a ring spinning machine manufactured by Toyota Industries Corporation, blended with 65% by weight of polylactic acid resin fiber of 40th cotton at a traveler rotation speed of 9000rpm and 35% by weight of degreased bleached cotton. I got a thread.

  Next, using this drawn yarn as warp and weft, a plain weave texture was produced. The raw machine had a warp density of 115 / 2.54 cm and a weft density of 85 / 2.54 cm. Furthermore, this raw machine was dyed under the following conditions to obtain a textile product.

<Fabric processing conditions>
a. Scouring soda ash 1g / L
Surfactant (Sanyo Kasei Co., Ltd., Gran Up US-20) 0.5g / L
Treatment conditions: 98 ° C. × 20 minutes b. Intermediate set Processing conditions: 180 ° C. × 3 minutes c. Dyeing Dianix Navy Blue ERFS 200
(Dianix Navy Blue ERFS 200) 2% owf
pH adjuster (acetic acid / sodium acetate buffer, pH 5) 0.2 g / L
Treatment conditions: 130 ° C. × 40 minutes d. Soaping surfactant (manufactured by Sanyo Kasei Co., Ltd., trade name Grand Up US-20) 0.2g / L
Treatment conditions: 60 ° C. × 20 minutes e. Finishing set Processing conditions: 160 ° C. × 3 minutes.

  The resin composition containing the polylactic acid resin obtained by melt-kneading and the fiber properties are as shown in Table 1. The obtained woven fabric was excellent in physical properties, durability and wet heat stability.

[Example 2]
Single fiber fineness in the same manner as in Example 1 except that 100 parts of polylactic acid stereocomplex and 1.5 parts of isocyanurate compound were prepared and melt kneaded so that the carboxyl group terminal concentration was 2 eq / ton. Produced a 3.0 dtex raw cotton, and after spinning, a textile product was obtained. The resin composition containing the polylactic acid resin obtained by melt kneading and the fiber properties are as shown in Table 1. The obtained woven fabric was excellent in physical properties, durability and wet heat stability.

[Example 3]
As the isocyanurate compound, monoallyl diglycidyl isocyanurate (“MADGIC” manufactured by Shikoku Kasei Kogyo Co., Ltd.) was mixed and prepared at a ratio of 1.0 part, and melt-kneaded so that the carboxyl group terminal concentration was 6 eq / ton. A raw cotton having a single fiber fineness of 3.0 dtex was produced in the same manner as in Example 1, and a textile product was obtained after spinning. Table 1 shows the polylactic acid resin composition and fiber properties obtained by melt kneading. The obtained woven fabric was excellent in physical properties, durability and wet heat stability.

[Example 4]
Single yarn fineness of 3.0 dtex in the same manner as in Example 1 except that 70 parts of PLA1 and 30 parts of PDA1 supplied to the twin screw extruder were prepared so that the carboxyl group terminal concentration was 15 eq / ton. After producing the raw cotton and spinning, a textile product was obtained. The resin composition containing the polylactic acid resin obtained by melt kneading and the fiber properties are as shown in Table 1. The obtained woven fabric was excellent in physical properties, durability and wet heat stability.

[Comparative Example 1]
Except that 100 parts of polylactic acid stereocomplex and 0.03 part of isocyanurate compound were melt-kneaded, drawn yarn and raw cotton were produced in the same manner as in Example 1, and spun yarn was prepared to produce a textile product. Obtained. The resin composition containing the polylactic acid resin obtained by melt-kneading and the fiber properties are as shown in Table 1. As a result, in Comparative Example 1, even after the reaction with the isocyanurate compound, the carboxyl group terminal concentration was as high as 30 eq / ton or more, so the molecular weight retention was low. Furthermore, the strength retention of the drawn yarn was less than 50%, and the fabric evaluated by the fabric iron after the jungle test was clearly cured, resulting in poor durability and wet heat stability.

[Comparative Example 2]
Except that a polylactic acid resin composition was prepared using PLA1, which is homopolylactic acid, as a polylactic acid resin, a drawn yarn and raw cotton were produced in the same manner as in Example 1, a spun yarn was produced, and a textile product was produced. Obtained. The resin composition containing the polylactic acid resin obtained by melt kneading and the fiber properties are as shown in Table 1.

  Since the polylactic acid resin was homopolylactic acid, there was no formation of a stereo complex, and the heat resistance and crystallization characteristics were inferior to those of the examples. Furthermore, the strength retention of the drawn yarn was less than 50%, and the fabric evaluated by the fabric iron after the jungle test was clearly cured, resulting in poor durability and wet heat stability.

Claims (2)

At least a part of the carboxyl group terminals of the polylactic acid block copolymer composed of a poly-L-lactic acid segment containing L-lactic acid as a main component and a poly-D-lactic acid segment containing D-lactic acid as a main component, The following general formula (1) with respect to 100 parts by mass of the polylactic acid block copolymer

Here, at least one of R1 to R3 is a glycidyl group, and the rest represents a functional group such as hydrogen, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, or an allyl group. A spun yarn comprising fibers made of a resin composition containing a polylactic acid resin blocked with 0.05 to 2 parts by mass of a nurate compound.   A woven or knitted fabric comprising the spun yarn according to claim 1.