JP2011058121A - Polylactic acid fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradability synthetic fiber consisting of raw materials of vegetable origin whose abrasion resistance is improved and a method for stably manufacturing the fiber. <P>SOLUTION: There is provided polylactic acid fiber containing spherical particles whose average particle diameters are equal to or 1 &mu;m or less by 0.01 to 5 wt.% with respect to total fiber weight and a method for manufacturing the polylactic acid fiber whose spinning is carried out by 500 to 5,000 m/min. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a polylactic acid fiber excellent in wear resistance.

  Various efforts to prevent global warming have been carried out, but there is an urgent need for the practical use of so-called biomass plastics derived from plant materials that pay attention to the action of plants fixing carbon dioxide in the atmosphere by photosynthesis. In particular, biomass plastics that are biodegraded by microorganisms without being incinerated after use have a low environmental impact in that both production and post-treatment depend on biological reactions. These polymers include polylactic acid, microorganism-produced polyester, polyamino acid, Examples include sugars. In particular, the production cost is relatively low, and at the same time, it often has practical heat resistance. Therefore, polylactic acid is expected as a biomass plastic that can be melt-molded. In addition, lactic acid, which is a monomer, has recently been manufactured at low cost by fermentation using microorganisms, and it has become possible to produce polylactic acid at a much lower cost, so that not only as a biodegradable polymer, The possibility of use as a general-purpose polymer has also been studied.

Furthermore, in order to provide a high melting point crystal to give practical heat resistance, by mixing poly-L-lactic acid (hereinafter referred to as PLLA) and poly-D-lactic acid (hereinafter referred to as PDLA). Polylactic acid stereocomplexes are known to be obtained, and this is described in Patent Documents 1 to 6, Non-Patent Documents 1 and 2, and the like. The polylactic acid stereocomplex is known to exhibit a high melting point and high crystallinity, and to give a molded product useful as a fiber, film, or resin molded product.
However, as a stereocomplex polylactic acid fiber, it does not satisfy the wear resistance in apparel use, and a polylactic acid fiber excellent in wear resistance has been highly desired.

JP-A-61-36321 JP 63-24014 A JP 2000-17163 A JP 2003-293220 A Japanese Patent Laid-Open No. 2005-23512 JP 2003-192894 A

Macromolecules, 24, 5651 (1991). Seni Gakkai Preprints (1989)

  An object of the present invention is to provide a polylactic acid fiber which is excellent in wear resistance and excellent in strength, dyeability and heat resistance. Another object of the present invention is to provide a textile product based on fibers made from the technique described in the present invention.

The present inventors have found that the presence of a lubricant having an average particle size of 1 μm or less in the polylactic acid fiber in advance prevents the progress of wear of the fiber and improves the wear resistance.
That is, according to the present invention,
A polylactic acid fiber containing 0.01 to 5% by weight of spherical particles having an average particle size of 1 μm or less, based on the total fiber weight,
Preferably, polylactic acid fibers whose spherical particles are inert spherical silica,
Polylactic acid (1) Poly L-lactic acid (A component) having a weight average molecular weight of 100,000 to 200,000, (2) Poly D-lactic acid (B component) having a weight average molecular weight of 100,000 to 200,000, and (3) A component And a component containing 0.01 to 5 parts by weight of a phosphoric acid ester metal salt per 100 parts by weight in total, with a strength of 3.0 to 7.0 cN / dtex, an elongation of 20 to 40%, A polylactic acid fiber having a shrinkage of 5 to 30% at 180 ° C.,
A polylactic acid fiber having a stereo ratio of polylactic acid of 90% or more as measured by wide-angle X-ray diffraction (XRD),
Polylactic acid containing spherical particles having an average particle size of 1 μm or less has a spinning speed of 500 to 5000 m / min. A method for producing polylactic acid fiber, characterized by spinning and drawing with
Is provided.

  The polylactic acid fiber of the present invention contains spherical particles having an average particle diameter of 1 μm or less, whereby the strength is 3.0 to 7.0 cN / dtex, the elongation is 20 to 40%, and the shrinkage at 180 ° C. is 5 It is -30%, and it can be set as the polylactic acid fiber with good process passage property and abrasion resistance.

The polylactic acid fiber of the present invention is a polylactic acid fiber containing spherical particles having an average particle diameter of 1 μm or less. Inert spherical particles are preferred. Inactive means that the ester bond of polylactic acid is not affected by decomposition or the like.
Here, the polylactic acid may be homopoly L-lactic acid, homopoly D-lactic acid, or stereocomplex polylactic acid obtained by blending poly L-lactic acid and poly D-lactic acid. In view of heat resistance and strength, stereocomplex polylactic acid is preferred.
The polylactic acid will be described.

(Poly L-lactic acid: A component)
Poly L-lactic acid mainly consists of L-lactic acid units. The L-lactic acid unit is a repeating unit derived from L-lactic acid. The poly L-lactic acid preferably contains 90 to 100 mol%, more preferably 95 to 100 mol%, still more preferably 98 to 100 mol% of L-lactic acid units. As other repeating units, a D-lactic acid unit or a unit other than lactic acid may be contained. The D-lactic acid unit and the units other than lactic acid are preferably 0 to 10 mol%, more preferably 0 to 5 mol%, still more preferably 0 to 2 mol%.

  Examples of units other than lactic acid include hydroxycarboxylic acids such as glycolic acid, caprolactone, butyrolactone, propiolactone, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-propanediol, 1,5 -Propanediol, hexanediol, octanediol, decanediol, dodecanediol, aliphatic diols having 2 to 30 carbon atoms, succinic acid, maleic acid, adipic acid, aliphatic dicarboxylic acids having 2 to 30 carbon atoms, terephthalic acid And units derived from one or more monomers selected from aromatic diols such as isophthalic acid, hydroxybenzoic acid, and hydroquinone, and aromatic dicarboxylic acids.

Poly L-lactic acid preferably has crystallinity, and the melting point is preferably 150 to 190 ° C, more preferably 160 to 190 ° C. When these conditions are satisfied, a stereocomplex crystal having a high melting point can be formed and the crystallinity can be increased.
The poly L-lactic acid has a weight average molecular weight of preferably 50,000 to 300,000, more preferably 100,000 to 250,000.

(Poly D-lactic acid: B component)
Poly D-lactic acid mainly consists of D-lactic acid units. The D-lactic acid unit is a repeating unit derived from D-lactic acid. The poly-D-lactic acid preferably contains 90 to 100 mol%, more preferably 95 to 100 mol%, and still more preferably 98 to 100 mol% of D-lactic acid units. Other repeating units include L-lactic acid units and units other than lactic acid. The L-lactic acid unit and the units other than lactic acid are preferably 0 to 10 mol%, more preferably 0 to 5 mol%, still more preferably 0 to 2 mol%.

  Examples of units other than lactic acid include hydroxycarboxylic acids such as glycolic acid, caprolactone, butyrolactone, propiolactone, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-propanediol, 1,5 -Propanediol, hexanediol, octanediol, decanediol, dodecanediol, aliphatic diols having 2 to 30 carbon atoms, succinic acid, maleic acid, adipic acid, aliphatic dicarboxylic acids having 2 to 30 carbon atoms, terephthalic acid And units derived from one or more monomers selected from aromatic diols such as isophthalic acid, hydroxybenzoic acid, and hydroquinone, and aromatic dicarboxylic acids.

The poly-D-lactic acid preferably has crystallinity, and the melting point is preferably 150 to 190 ° C, more preferably 160 to 190 ° C. When these conditions are satisfied, a stereocomplex crystal having a high melting point can be formed and the crystallinity can be increased.
Poly D-lactic acid has a weight average molecular weight of preferably 100,000 to 200,000, more preferably 110,000 to 170,000.

  Poly-L-lactic acid or poly-D-lactic acid is produced by a method of directly dehydrating condensation of L-lactic acid or D-lactic acid, or L-lactic acid or D-lactic acid is once subjected to dehydration cyclization to form lactide, followed by ring-opening polymerization. It can be manufactured by a method. Catalysts used in these methods include divalent tin compounds such as tin octylate, tin chloride, and tin alkoxides, tetravalent tin compounds such as tin oxide, butyltin oxide, and ethyltin oxide, metal tin, zinc compounds, aluminum compounds, Examples include calcium compounds and lanthanide compounds.

  For poly L-lactic acid and poly D-lactic acid, it is preferable that the polymerization catalyst used in the polymerization is washed away with a solvent or the catalytic activity is deactivated. A catalyst deactivator can be used to inactivate the catalyst activity.

As a catalyst deactivator, an organic ligand consisting of a group of chelate ligands having an imino group and capable of coordinating to a metal polymerization catalyst, a phosphorus oxoacid, a phosphorus oxoacid ester, and an organic phosphorus oxoacid compound represented by the formula (3) There may be mentioned at least one selected from the group. The catalyst deactivator is preferably blended in an amount of 0.3 to 20 equivalents, more preferably 0.4 to 15 equivalents, and even more preferably 0.5 to 10 equivalents per equivalent of the metal element in the catalyst at the end of the polymerization. .
_{X 1 -P (= O) m} (OH) n (OX 2) 2-n (3)
In the formula, m is 0 or 1, n is 1 or 2, and X ₁ and X ₂ each independently represent a hydrocarbon group optionally having a substituent having 1 to 20 carbon atoms. Examples of the hydrocarbon group include alkyl groups having 1 to 20 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group.

  The metal ion content in poly L-lactic acid and poly D-lactic acid is preferably 20 ppm or less from the viewpoint of heat resistance and hydrolysis resistance of the fiber. The metal ion content is preferably such that the content of each metal selected from alkaline earth metals, rare earths, transition metals of the third period, aluminum, germanium, tin and antimony is 20 ppm or less.

Next, stereocomplex polylactic acid will be described.
The ratio of poly L-lactic acid (A component) to poly D-lactic acid (B component) in stereocomplex polylactic acid is A component / B component (weight), preferably 40 / 60-60 / 40, more preferably Is 45/55 to 55/45, more preferably 50/50.
The following phosphoric acid ester metal salt (component C) is added to the polylactic acid in the above ratio.

(Phosphate metal salt: C component)
As the phosphoric acid ester metal salt (component C), a compound represented by the following formula (1) or (2) is preferably exemplified. The phosphoric acid ester metal salt may be used alone or in combination.

In Formula (1), R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms represented by R ¹ include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a sec-butyl group, and an iso-butyl group. The
R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. Examples of the alkyl group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group, amyl group, tert-amyl group, hexyl group, heptyl group, octyl group, iso-octyl group, tert-octyl group, 2-ethylhexyl group, nonyl group, iso-nonyl group, decyl group, iso-decyl group, tert-decyl group, An undecyl group, a dodecyl group, a tert-dodecyl group, etc. are mentioned.
M ₁ represents an alkali metal atom such as Na, K or Li or an alkaline earth metal atom such as Mg or Ca. p represents 1 or 2.
Preferable examples of the phosphoric acid ester metal salt represented by the formula (1) include those in which R ₁ is a hydrogen atom and R ₂ and R ₃ are both tert-butyl groups.

In the formula (2), R ₄ , R ₅ and R ₆ each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. Examples of the alkyl group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group, amyl group, tert-amyl group, hexyl group, heptyl group, octyl group, iso-octyl group, tert-octyl group, 2-ethylhexyl group, nonyl group, iso-nonyl group, decyl group, iso-decyl group, tert-decyl group, An undecyl group, a dodecyl group, a tert-dodecyl group, etc. are mentioned.
M ₂ represents an alkali metal atom such as Na, K or Li or an alkaline earth metal atom such as Mg or Ca. p represents 1 or 2.
Preferred examples of the phosphoric acid ester metal salt represented by the formula (2) include those in which R ⁴ and R 6 are methyl groups and R ⁵ is a tert-butyl group. As a phosphoric acid ester metal salt, trade name, NA-11, manufactured by ADEKA Co., Ltd. can be mentioned. The phosphoric acid ester metal salt can be synthesized by a known method.

As described in JP-A-2003-192884, the compound represented by the formula (1) or (2) is a compound known as a crystal nucleating agent for polylactic acid. However, in the present invention, M1 and M2 in the formulas (1) and (2) are an alkali metal atom or an alkaline earth metal atom. When M ₁ and M _{2 in the} formulas (1) and (2) are other metals such as aluminum, the heat resistance of the compound itself is low, and a sublimate is generated during spinning, which makes it difficult to spin. There is a case.

  The phosphoric acid ester metal salt (component C) preferably has an average primary particle size of 0.01 to 10 μm, more preferably 0.05 to 7 μm. It is industrially difficult to make the particle size smaller than 0.01 μm, and it is not necessary to make it so small. On the other hand, if it is larger than 10 μm, the frequency of yarn breakage increases during spinning and drawing.

  The content of the phosphoric acid ester metal salt (component C) is 0.01 to 5 parts by weight per 100 parts by weight in total of the poly L-lactic acid (component A) and the poly D-lactic acid (component B), preferably 0.00. 05 to 5 parts by weight, more preferably 0.05 to 4 parts by weight, particularly preferably 0.1 to 3 parts by weight. If the amount is less than 0.01 parts by weight, the desired effect is hardly recognized. On the other hand, if it is used in a larger amount than 5 parts by weight, it is not preferable because thermal decomposition or fiber breakage may occur during fiber formation.

  The spherical particles need to have an average particle diameter of 1 μm or less, and if it exceeds 1 μm, the fiber strength is lowered. Preferably it is 0.01-1 micrometer. As the inert spherical particles, preferably spherical silica is used.

The content of the spherical particles is preferably 0.01 to 5% with respect to the total fiber weight, and if it is less than 0.01%, the effect of wear resistance is low, and if it exceeds 5%, the fiber strength decreases. Preferably it is 0.01 to 2%, more preferably 0.01 to 0.5%.
By containing spherical particles, it is considered that the friction coefficient with respect to the fiber and / or metal on the fiber surface is reduced, and the process passability and the wear resistance of the product are improved.

  Moreover, conventionally well-known various methods can be used for the mixing method in the case of mixing a spherical particle, polylactic acid, phosphate ester metal salt, etc. For example, they can be mixed with a tumbler, V-type blender, super mixer, nauta mixer, Banbury mixer, kneading roll, monoaxial or biaxial extruder.

The composition thus obtained can be melt-mixed and transferred to the spinning device as it is or via a metering pump. The temperature for melting and mixing is preferably higher than the melting point of the resulting stereocomplex polylactic acid, and preferably higher than 220 ° C. Further, it may be once pelletized and then supplied to the spinning device. The pellet length is preferably 1 to 7 mm, the major axis is 3 to 5 mm, and the minor axis is 1 to 4 mm. The pellet shape is preferably uniform. The pelletized composition can be transferred to a spinning device using a normal melt extruder such as a pressure melter type or a single-screw or twin-screw extruder type. In forming the stereocomplex crystal, it is important to sufficiently mix the A component and the B component, and it is particularly preferable to mix them under shear stress.
The composition may contain a carbodiimide compound. Thermal decomposition and hydrolysis resistance obtained by containing a carbodiimide compound are improved.

  As carbodiimide compounds, dicyclohexylcarbodiimide, diisopropylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, octyldecylcarbodiimide, di-tert-butylcarbodiimide, dibenzylcarbodiimide, diphenylcarbodiimide, N-octadecyl-N′-phenylcarbodiimide, N-benzyl-N ′ -Phenylcarbodiimide, N-benzyl-N'-tolylcarbodiimide, di-o-toluylcarbodiimide, di-p-toluylcarbodiimide, bis (p-aminophenyl) carbodiimide, bis (p-chlorophenyl) carbodiimide, bis (o-chlorophenyl) ) Carbodiimide, bis (o-ethylphenyl) carbodiimide, bis (p-ethylphenyl) carbodiimi Bis (o-isopropylphenyl) carbodiimide, bis (p-isopropylphenyl) carbodiimide, bis (o-isobutylphenyl) carbodiimide, bis (p-isobutylphenyl) carbodiimide, bis (2,5-dichlorophenyl) carbodiimide, bis (2 , 6-Dimethylphenyl) carbodiimide, bis (2,6-diethylphenyl) carbodiimide, bis (2-ethyl-6-isopropylphenyl) carbodiimide, bis (2-butyl-6-isopropylphenyl) carbodiimide, bis (2,6 -Diisopropylphenyl) carbodiimide, bis (2,6-di-tert-butylphenyl) carbodiimide, bis (2,4,6-trimethylphenyl) carbodiimide, bis (2,4,6-triisopropylphenyl) Carbodiimide, bis (2,4,6-tributylphenyl) carbodiimide, diβ-naphthylcarbodiimide, N-tolyl-N′-cyclohexylcarbodiimide, N-tolyl-N′-phenylcarbodiimide, p-phenylenebis (o-toluylcarbodiimide) P-phenylenebis (cyclohexylcarbodiimide, p-phenylenebis (p-chlorophenylcarbodiimide), 2,6,2 ′, 6′-tetraisopropyldiphenylcarbodiimide, hexamethylenebis (cyclohexylcarbodiimide), ethylenebis (phenylcarbodiimide), Examples thereof include mono- or polycarbodiimide compounds such as ethylenebis (cyclohexylcarbodiimide).

  Examples of such commercially available polycarbodiimide compounds include Carbodilite LA-1 and HMV-8CA sold under the trade name of Carbodilite sold by Nisshinbo Co., Ltd.

  The composition preferably has a moisture content of 100 ppm or less. When the moisture content is high, hydrolysis of the poly L-lactic acid component and the poly D-lactic acid component is promoted, the molecular weight is remarkably lowered, spinning becomes difficult, and physical properties of the obtained yarn are lowered, which is not preferable.

  Further, the amount of residual lactide in the composition is preferably 3,000 ppm or less, more preferably 1,000 ppm or less, and particularly preferably 400 ppm or less. Since lactide in the polylactic acid obtained by the lactide method may vaporize during melt spinning and cause yarn unevenness, it is preferable for the purpose of obtaining a good yarn to suppress the lactide amount to 400 ppm or less.

(Melt spinning)
The composition is melted by an extruder type or pressure melter type melt extruder, measured by a gear pump, filtered in a pack, and then discharged as a monofilament, multifilament, etc. from a nozzle provided on the base. And spun. The shape of the base and the number of the bases are not particularly limited, and any of circular, irregular, solid, hollow and the like can be adopted. The discharged yarn is immediately cooled and solidified, then converged, added with oil, and wound. The winding speed at this time is 500 to 5000 m / min, preferably 500 to 3000 min. It is. When the winding speed is less than 500 m / min, it is necessary to stretch at a high magnification in order to obtain a sufficient strength. Therefore, an increase in fluff and the occurrence of frequent yarn breaks occur, resulting in stable yarn production. Have difficulty. In the case of a high speed exceeding 5000 m / min, single yarn breakage or yarn breakage due to rubbing with a roller or a guide during spinning is not preferable.
By including the spherical particles, the abrasion of the fibers is small and the process passability is good even at the spinning speed as described above.

(Stretching)
Stretching needs to be carried out at 1.5 to 6.0 times. If it is less than 1.5 times, sufficient strength cannot be obtained, and if it exceeds 6.0 times, strength reduction due to whitening due to devitrification, single yarn breakage, or yarn breakage occurs. The preheating for stretching can be performed by using a plate-type or pin-shaped contact heater, non-contact hot plate, heating medium bath, etc. in addition to raising the temperature of the roll. The stretching temperature is preferably 70 to 140 ° C, more preferably 80 to 130 ° C.

(Heat treatment)
The heat treatment step is a step of heat treating the drawn yarn. The heat treatment is performed at 160 to 230 ° C, preferably 170 to 220 ° C, more preferably 180 to 200 ° C. For the heat treatment, it is necessary to use a contact heater such as a hot roller or a plate heater, and the heat treatment may be continuous with or separated from the stretching step. By heat-treating, it is possible to obtain a fiber having a high stereo ratio, excellent heat shrink resistance and iron resistance, and a strength of 3.0 cN / dtex or more. Further, if heat treatment is performed at a temperature lower than 150 ° C., a sufficient stereoization ratio cannot be obtained, which may cause problems in heat shrink resistance and iron resistance.
In the present invention, the spinning drawing step may be direct spinning drawing or may be a method of winding and drawing once.

<fiber>
The polylactic acid fiber of the present invention has a strength of 3.0 to 7.0 cN / dtex. Stereocomplex polylactic acid containing A component, B component and C component is preferred. The strength of the polylactic acid fiber of the present invention is 3.0 cN / dtex or more, more preferably 3.5 cN / dtex or more. The higher the upper limit, the better. However, the upper limit is actually about 7.0 cN / dtex. When the strength is 7.0 cN / dtex or more, it is necessary to increase the molecular weight of the polymer to be used, which is not preferable because the spinning property is lowered.

  The polylactic acid fiber of the present invention has a heat shrinkage rate at 150 ° C. of preferably 5.0 to 30.0%, more preferably 6.0 to 20.0%, still more preferably 8.0 to 15.0%. It is. If the heat shrinkage rate is large, the textile product shrinks and becomes smaller when it is exposed to high temperatures, such as ironing, and becomes unusable.

  The stereo ratio of the polylactic acid fiber of the present invention is preferably 90 to 100%, more preferably 95 to 100%, and still more preferably 98 to 100%. In the differential scanning calorimeter (DSC) measurement, It has a single melting peak, the melting peak temperature is 195 ° C. or higher, and the stereoization rate by wide-angle X-ray diffraction (XRD) measurement is 90% or higher.

<Fiber products>
The polylactic acid fiber of the present invention can also be used as a raw yarn for yarn processing such as false twisting, mechanical crimping, and indentation crimping. Moreover, it can also be set as the spun yarn using a long fiber, a short fiber, and a short fiber. Since the fiber of the present invention has a high stereo ratio and is excellent in strength, heat resistance and low heat shrinkability, it can be made into various garment fiber products such as woven fabrics, knitted fabrics and nonwoven fabrics.

Hereinafter, the present invention will be described more specifically with reference to examples.
Strength and elongation:
The measurement was performed using a “Tensilon” tensile tester manufactured by Orientec Co., Ltd. under the conditions of a sample length of 25 cm and a tensile speed of 30 cm / min.
Thermal shrinkage:
Shrinkage at 180 ° C. Measured according to JIS L-1013 8.18.2 a).
Fiber abrasion test:
The test equipment and test method for the wear test are in accordance with JIS-L1095 9.10.2 wear strength method B. The test is repeated 10 times until all yarns are broken and the minimum and maximum values are set. The average value of the 8 points excluding was used as the number of times of fiber wear.

(Production of polylactic acid)
Polymerization of the polylactic acid polymer was performed by the following method.
After adding 300 parts of L-lactide to the flask and substituting the system with nitrogen, 0.4 part of stearyl alcohol and 0.02 part of tin octylate as a catalyst were added, polymerized at 190 ° C. for 2 hours, and finally reduced in pressure. And the monomer was removed to obtain L-polylactic acid. Next, after adding 300 parts of D-lactide to the flask and replacing the system with nitrogen, 0.59 parts of stearyl alcohol and 0.02 part of tin octylate as a catalyst were added, and polymerization was carried out at 190 ° C. for 2 hours. D-polylactic acid was obtained by subjecting to a reduced pressure treatment.

[Example 1]
After blending 50 parts by weight of L-polylactic acid prepared from 90 mol% of L-lactide and 50 parts by weight of D-polylactic acid prepared from 90 mol% of D-lactide, the average Silica with a particle size of 0.35μm (Nippon Shokubai Sea Hoster KE30) is blended in a dry state so as to be 0.1 parts by weight with respect to the total weight of polylactic acid, and melt-extruded with a kneading extruder to form a pellet. I got a thing. The polymer here was melt-spun at 240 ° C. using a die having 36 perforations and wound up at 1000 m / min. The obtained unstretched yarn was stretched in two stages at a stretching temperature of 80 ° C., a second roller temperature of 100 ° C., and a heat setting roller temperature of 180 ° C. at the magnifications shown in Table 1, and wound at a winding speed of 500 m / min. The drawing processability at this time was good, and the drawing processability was good with no drawing breakage during the 2-hour drawing. The fineness of the obtained drawn yarn was 101 dtex, the tensile strength was 4.6 cN / dtex, the elongation was 31%, the hot water shrinkage was 6.3%, and the melting point obtained from DSC measurement of the drawn yarn was 215 ° C. It was. The results are shown in Table 1.

[Examples 2 to 5]
A drawn yarn was obtained by spinning and drawing in the same manner as in Example 1 except that the blending ratio of silica having an average particle size of 0.35 μm was as shown in Table 1. Table 1 shows the physical property results and evaluation results of the drawn yarn.

[Example 6]
Chip blending was performed using a V-type blender at a ratio of the above poly L lactic acid / poly D lactic acid = 50/50 (weight ratio), and then dried under reduced pressure at 110 ° C. for 5 hours. Example except that 0.5 parts by weight of 2,2-methylenebis (4,6-di-tert-butylphenol) sodium salt (Adeka Stub NA-11) (average particle size 5 μm) phosphate was added to 100 parts by weight of this chip. 1 was performed.

[Comparative Examples 1 and 2]
A drawn yarn was obtained by spinning and drawing in the same manner as in Example 1 except that the blending ratio of silica having an average particle size of 0.35 μm was as shown in Table 1. Table 1 shows the physical property results and evaluation results of the drawn yarn.

  Since the wear resistance of the polylactic acid fiber of the present invention is improved, it is used for clothing such as shirts, blousons, pants and coats, used for clothing materials such as cups and pads, interior uses such as curtains, carpets, mats and furniture, belts, nets, It can also be suitably used for industrial material applications such as ropes, heavy cloth, bags, felts, filters, etc., and vehicle interior applications.

Claims (5)

  A polylactic acid fiber comprising 0.01 to 5% by weight of spherical particles having an average particle size of 1 μm or less based on the total fiber weight.   The polylactic acid fiber according to claim 1, wherein the spherical particles are spherical silica.   Polylactic acid (1) Poly L-lactic acid (A component) having a weight average molecular weight of 100,000 to 200,000, (2) Poly D-lactic acid (B component) having a weight average molecular weight of 100,000 to 200,000, and (3) A component And a component containing 0.01 to 5 parts by weight of a phosphoric acid ester metal salt per 100 parts by weight in total, with a strength of 3.0 to 7.0 cN / dtex, an elongation of 20 to 40%, The polylactic acid fiber according to claim 1, which has a shrinkage rate at 180 ° C. of 5 to 30%.   The polylactic acid fiber according to any one of claims 1 to 3, wherein a stereo ratio of polylactic acid as measured by wide-angle X-ray diffraction (XRD) is 90% or more.   Polylactic acid containing spherical particles having an average particle size of 1 μm or less has a spinning speed of 500 to 5000 m / min. A process for producing a polylactic acid fiber, characterized by spinning and drawing with