JP3614020B2 - Method for producing aliphatic polyester multifilament - Google Patents

Description

【００３１】
（実施例２）
Ｌ−ラクチドにＬ−乳酸およびＤ−乳酸からなるラクチド（ラセミ体）を混合した後に重合して融点１５５℃、重量平均分子量１１．５万のＤ体共重合率５ｍｏｌ％ポリＬ−乳酸共重合体を得た。このポリマーを用いて溶融紡糸を行ったこと以外は実施例１と同様に製糸を行い、表１に記載した延伸段数、延伸倍率、延伸温度で未延伸糸の延伸を行うことにより、Ｄ体共重合率５ｍｏｌ％ポリＬ−乳酸共重合体（Ｐ（Ｌ／Ｄ）ＬＡ）からなる延伸糸を得た。この延伸糸を用いて前記した生分解性評価を行った。
延伸糸の強度、延伸時の延伸性、生分解性をそれぞれ表１に併せて示す。
【００３２】
（実施例５，７〜８）
未延伸糸の巻取り速度を２２００ｍ／分とした以外は実施例１と同様に製糸を行い、表１に記載した延伸段数、延伸倍率、延伸温度で未延伸糸の延伸を行うことにより、ＰＬＬＡからなる延伸糸を得た。この延伸糸を用いて前記した生分解性評価を行った。
延伸糸の強度、延伸時の延伸性、生分解性をそれぞれ表１に併せて示す。
【００３３】
（実施例９）
Ｌ−ラクチドの重合温度を１９８℃、重合時間を１５分、固相重合温度を１４７℃とすることにより融点１７８℃、重量平均分子量１８．７万のＰＬＬＡを得て、このポリマーを用いて溶融紡糸を行い、未延伸糸の巻取り速度を２２００ｍ／分とした以外は実施例１と同様に製糸を行い、表１に記載したとおりの延伸段数、延伸倍率、延伸温度で未延伸糸の延伸を行うことにより、ＰＬＬＡからなる延伸糸を得た。この延伸糸を用いて前記した生分解性評価を行った。
延伸糸の強度、延伸時の延伸性、生分解性をそれぞれ表１に併せて示す。
【００３４】
（比較例１）
融点２５６℃、極限粘度１．０２のポリエチレンテレフタレート（ＰＥＴ）を１３０℃で１２時間減圧乾燥した後、溶融紡糸した。環状３列配孔で０．６φの吐出孔を９６個持つ口金を用い、押し出しにはエクストルダー型の溶融紡糸機を用いた。以上の条件のもとで上記のＰＥＴを用いて紡糸温度２９５℃で溶融紡糸し、口金から紡出直後長さ３００ｍｍ、温度３２０℃の加熱筒内の雰囲気を通過させた後、環状チムニーを通過させて風速１３ｍ／分のチムニー風により冷却し油剤を付与した後、１５００ｍ／分の速度で引取ることにより３３３０ｄｔｅｘ／９６ｆｉｌの未延伸糸を一旦巻き取った。この未延伸糸を表１に記載したとおりの延伸段数、延伸倍率、延伸温度にて延伸し、引き続いて温度１５５℃において熱固定、０．５％の弛緩処理を施して巻取り速度３２０ｍ／分にて延伸糸を巻取った。この延伸糸を用いてそれぞれ前記した生分解性評価を行った。
延伸糸の強度、延伸時の延伸性、生分解性をそれぞれ表１に示す。
【００３５】
（比較例２）
Ｌ−ラクチドの重合温度を１８０℃、重合時間を６分、固相重合温度を１３０℃とすることにより融点１７６℃、重量平均分子量７．９万のＰＬＬＡを得て、このポリマーを用いて溶融紡糸を行ったこと以外は実施例１と同様に製糸を行い、表１に記載したとおりの延伸段数、延伸倍率、延伸温度で未延伸糸の延伸を行うことにより、ＰＬＬＡからなる延伸糸を得た。この延伸糸を用いて前記した生分解性評価を行った。
延伸糸の強度、延伸時の延伸性、生分解性をそれぞれ表１に併せて示す。
【００３６】
（比較例３）
融点１１２℃、重量平均分子量１２．４万のポリブチレンサクシネート（ＰＢＳ）を８０℃で１２時間減圧乾燥した後、溶融紡糸した。環状３列配孔で０．６φの吐出孔を９６個持つ口金を用い、押し出しにはエクストルダー型の溶融紡糸機を用いた。以上の条件のもとで上記のポリブチレンサクシネートを用いて紡糸温度１８０℃で溶融紡糸し、口金から紡出直後長さ３００ｍｍ、温度２００℃の加熱筒内の雰囲気を通過させた後、環状チムニーを通過させて風速２５ｍ／分のチムニー風により冷却し油剤を付与した後、１５００ｍ／分の速度で引取ることにより３３３０ｄｔｅｘ／９６ｆｉｌの未延伸糸を一旦巻き取った。この未延伸糸を表１に記載した延伸段数、延伸倍率、延伸温度にて延伸し、引き続いて温度１５５℃において熱固定、０．５％の弛緩処理を施して巻取り速度３２０ｍ／分にて延伸糸を巻取った。この延伸糸を用いてそれぞれ前記した生分解性評価を行った。
延伸糸の強度、延伸時の延伸性、生分解性をそれぞれ表１に併せて示す。
【００３７】
（比較例４）
未延伸糸の巻取り速度を７５０ｍ／分とした以外は実施例１と同様に製糸を行い、表１に記載したとおりの延伸段数、延伸倍率、延伸温度で未延伸糸の延伸を行うことにより、ＰＬＬＡからなる延伸糸を得た。この延伸糸を用いて前記した生分解性評価を行った。
延伸糸の強度、延伸時の延伸性、生分解性をそれぞれ表１に併せて示す。
【００３８】
【発明の効果】
本発明の脂肪族ポリエステル繊維の製造方法により、高倍率延伸においても毛羽や糸切れが極めて少なく延伸性が良好で安定した延伸を行うことができ、低コストで効率の良い生産を行うことができる。得られる脂肪族ポリエステル繊維は、高強度でなおかつ毛羽や白化現象がない極めて品位の優れたものであり、衣料用および産業用として広く好適かつ有用である。
【００３９】
さらに、これらの繊維は自然環境中での生物分解性が高く、使用後は自然環境中で容易に分解されるという利点を有する。加えて、使用する繊維の繊度や繊維構造、あるいは織り設計やコーティングにより織物や製品の設計を変更することにより、分解性を任意に制御することができる。
【図面の簡単な説明】
【図１】本発明の実施形態の一例の延伸工程図。
【符号の説明】
１：延伸ローラー
２：熱セットローラー
３：リラックスローラー
４：接触式熱板
５：巻取機
６：糸道ガイドローラー
７：スイングアーム
８：給糸部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an aliphatic polyester fiber. More specifically, the present invention relates to a method for stably and efficiently producing a high-strength aliphatic polyester multifilament.
[0002]
[Prior art]
Conventionally, polyethylene, polypropylene, polyester, polyamide, and the like have been used as materials for fibers and molded products, and consumption has been increasing year by year. Along with this, the amount of waste after use has also increased. Since these wastes are currently treated by incineration or landfill, various environmental problems and problems such as securing a disposal site have occurred, and the development of new treatment methods is urgently needed.
[0003]
As one of new processing methods, there is a method of collecting a recyclable resin and reusing it after separation. However, in reality, it is difficult to recover, and high technology and expensive equipment are required to separate the resin. Furthermore, with the current technology, there is a limit to the number of reuses, and at most after 2-3 recyclings, they are also processed by incineration or landfill.
[0004]
Therefore, recently, from the viewpoint of global environmental conservation, various biodegradable polymers have been developed that decompose resins in the natural environment by the action of microorganisms present in soil and water. Among these, as the biodegradable polymer that can be melt-molded, for example, an aliphatic group comprising an aliphatic dicarboxylic acid component such as polyhydroxybutyrate, polycaprolactone, succinic acid or adipic acid and a glycol component such as ethylene glycol or butanediol. Polyester, polylactic acid and the like are known. However, mechanical properties such as strength and elastic modulus are not sufficiently high as compared with conventional general-purpose fibers such as polyester and nylon, and they have been used only for limited applications such as surgical sutures.
[0005]
In recent years, various attempts have been made to solve such problems. For example, JP-A-3-183428 and JP-A-4-108331 disclose a technique for achieving high strength by performing high-strength drawing or solution spinning using a high molecular weight polymer. However, both of these are monofilament production technologies, and there is no suggestion about the industrial production technology of multifilaments that are completely different in terms of yarn production conditions such as the take-up speed and drawing speed of undrawn yarn. High-strength aliphatic polyester multifilaments could not be industrially produced efficiently only by adjusting the conditions. Furthermore, Japanese Patent Application Laid-Open No. 10-60733 discloses a technique for obtaining a polylactic acid monofilament having a high strength and a high elastic modulus by drawing two or more stages with hot water. However, it is very difficult to apply hot water drawing to melt spinning of multifilament which is much faster. Japanese Patent Application Laid-Open No. 8-222016 also discloses a technique for obtaining a high strength / high elongation yarn of 8 g / d, 30% or more by high magnification drawing using a polylactic acid polymer having a weight average molecular weight of 100,000 to 500,000. It is disclosed. However, as is clear from the examples, the technique of the publication is intended to stretch the monofilament at a high magnification by one-stage drawing, and even if the same technique is applied to the multifilament, There was a problem that single yarn was frequently broken, and it was not possible to obtain an industrially stable and high-quality yarn. Furthermore, Japanese Patent Application Laid-Open No. 7-305227 discloses a technique for solving the problem of stretchability while achieving high strength by performing continuous polymerization spinning of polylactic acid copolymerized with a small amount of polyethylene glycol. ing. However, it is expensive due to copolymerization and heat resistance is reduced, or a large-scale apparatus is necessary for continuous polymerization spinning, and it is difficult to obtain a stable quality yarn with difficult quality control. There were problems such as.
[0006]
As described above, various attempts have been made to obtain high-strength aliphatic polyester fibers. Regarding the stable and efficient production of aliphatic polyester multifilaments with high strength and excellent mechanical strength, The actual situation has not yet been achieved.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for stably and efficiently producing an aliphatic polyester multifilament having high strength, excellent mechanical strength, and excellent quality, which could not be achieved by the prior art as described above. is there.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the method for producing an aliphatic polyester multifilament of the present invention mainly has the following configuration. That is,weightAverage molecular weight 100,000Polylactic acid based on ˜400,000 L-lactic acid and / or D-lactic acidBased onAliphatic polyesterPolymer melt-spun, take-up speed 1200~ 2200m / minAfter picking up2-stage or 3-stageIn performing multi-stage stretching, an aliphatic polyester multifilament manufacturing method is characterized in that the draw ratio Mn of the n-th stage (1 ≦ n ≦ N) satisfies the following formula (1).
(1) 1 ≦ Mn ≦ M_T ^{1 / N}× 1.5
However, M_TIs the total draw ratio (M_T= M₁× M₂× ・ ・ ・ × M_N), N is the number of stretching stages (N ≧ 2).
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, the manufacturing method of the aliphatic polyester multifilament of this invention is demonstrated.
[0010]
Used in the method for producing an aliphatic polyester multifilament of the present inventionAliphatic polyesterThe polymerIt is mainly composed of polylactic acid mainly composed of L-lactic acid and / or D-lactic acid. Normally,Melting point is 130 ° C or higher, preferably 150 ° C or higher, more preferably 170 ° C or higher.Aboveis there.
[0011]
If the melting point of the aliphatic polyester is lower than 130 ° C., the fusion between the single fibers becomes remarkable during spinning, particularly spinning, and the quality of the product is remarkably impaired such as poor stretchability. In addition, in this invention, melting | fusing point means the peak temperature of the melting peak obtained by DSC measurement, and means the value measured by the method as described in an Example.
[0012]
The present inventionForAliphatic polyesterIs a polylactic acid based on L-lactic acid and / or D-lactic acid.TheIt is the subject. PolyCopolymerization of -3-hydroxypropionate, poly-3-hydroxybutyrate and poly-3-hydroxybutyrate valeratethe body'sAmong them, the polylactic acid-based biodegradable polymer has excellent characteristics such as higher heat resistance and crystallinity than other biodegradable polymers, and high strength and elastic modulus when used as a fiber. These aliphatic polyesters are highly biodegradable or hydrolyzable and have the advantage of being easily degraded in the natural environment after use. Furthermore, the degradability can be controlled by changing various designs such as a woven structure and a knitted structure depending on the fineness and form of the fiber or the application to be used.
[0013]
The weight average molecular weight of the aliphatic polyester used in the present invention is 100,000 or more, preferably 120,000 or more, more preferably 150,000 or more. When the weight average molecular weight is less than 100,000, the strength properties of the fiber cannot be made excellent. In general, it is difficult to set the average molecular weight of the aliphatic polyester to 400,000 or more.
[0014]
In addition, you may contain components other than the aliphatic polyester which makes the main body in the polymer used by this invention in the range which does not impair the effect of this invention. For example, inorganic fine particles or organic compounds may be added as necessary as plasticizers, UV stabilizers, matting agents, deodorants, flame retardants, yarn friction reducing agents, antioxidants, or coloring pigments. In particular, benzophenone, benzotriazole, and hindered amine agents can be preferably used as the ultraviolet stabilizer. The blending amount at this time is preferably 0.005 to 1.0 wt% with respect to the fiber weight. Color pigments include inorganic pigments such as titanium oxide and carbon black, as well as cyanine, styrene, phthalocyanine, anthraquinone, perinone, isoindolinone, quinophthalone, quinocridone, and thioindigo. Things can be used.
[0015]
From the viewpoint of obtaining mechanical and physical properties such as strength and elastic modulus, light resistance, and heat resistance as clothing and industrial fibers, the aliphatic polyester that is the main component of the polymer used in the present invention is L- Polylactic acid containing lactic acid and / or D-lactic acid as a main component is preferable. The polylactic acid production method includes a two-stage lactide method in which L-lactic acid, D-lactic acid, and DL-lactic acid (racemic) are used as raw materials to once form lactide, which is a cyclic dimer, followed by ring-opening polymerization. A one-step direct polymerization method in which the raw material is directly subjected to dehydration condensation in a solvent is known. The polylactic acid used in the present invention may be obtained by any method. In the case of a polymer obtained by the lactide method, the cyclic dimer contained in the polymer is vaporized at the time of melt spinning to cause yarn unevenness. Therefore, the cyclic dimer contained in the polymer at a stage before melt spinning. The content of is desirably 0.3 wt% or less. In the case of the direct polymerization method, there is substantially no problem due to the cyclic dimer.
[0016]
The polylactic acid preferably used in the present invention may be a copolymerized polylactic acid obtained by copolymerizing other monomer components having ester forming ability in addition to L-lactic acid and D-lactic acid. Examples of copolymerizable monomer components include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, and other hydroxycarboxylic acids, as well as ethylene glycol, propylene glycol, and butane. Compounds containing a plurality of hydroxyl groups in the molecule such as diol, neopentyl glycol, polyethylene glycol, glycerin, pentaerythritol or derivatives thereof, succinic acid, adipic acid, sebacic acid, fumaric acid, terephthalic acid, isophthalic acid, 2 , 6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid and the like, or compounds containing a plurality of carboxylic acid groups in the molecule.
[0017]
In order to reduce the melt viscosity, aliphatic polyester polymers such as polycaprolactone, polybutylene succinate, and polyethylene succinate can be used as an internal plasticizer or as an external plasticizer.
[0018]
In the method for producing an aliphatic polyester multifilament of the present invention, a high-strength aliphatic polyester multifilament can be obtained by using an ordinary melt spinning apparatus / equipment. That is, the polymer described above is melted by, for example, an extruder or a pressure melter type spinning machine, measured by a metering pump, filtered in a spinning pack, etc., and then discharged from a multifilament porous die. . The discharged yarn is cooled and solidified by being blown with a gas having a temperature lower than the melting point of the polymer, and then an oil agent is applied, taken out, and then drawn. It is preferable to use an airflow suction device in order to remove sublimates from the discharged yarn at the upstream side of cooling or at the cooling section. Furthermore, it is preferable from the point of increasing the strength of the fiber that a heating zone is provided immediately before spinning and before cooling and solidification to heat the yarn to a temperature higher than the melting point of the polymer. For cooling, either a circular chimney or a uniflo chimney can be used. Either the two-step method of winding once before drawing or the direct spinning drawing method in which drawing is continued without winding after spinning may be used. However, from the viewpoint of productivity, the direct spinning drawing method is used. Is preferred.
[0019]
Conventionally, when melt spinning and drawing a high molecular weight aliphatic polyester, it has been difficult to increase the draw ratio in order to obtain a high strength yarn. As a result of intensive studies on this problem, the present inventors have found that the problem of stretchability is caused by the brittle nature of the undrawn yarn taken, and that it is caused by the low take-up speed of the undrawn yarn. I figured out what I was doing. In the method for producing an aliphatic polyester multifilament of the present invention, the take-up speed is 1200 m / min or more, preferably 1800 m / min or more. That is, in an undrawn yarn obtained by melt spinning high molecular weight aliphatic polyester and taking it at a speed lower than 1200 m / min, lamellar folded crystals are formed due to the relaxed fiber internal structure with almost no orientation crystallization. At the same time as the pick-up, it grows rapidly and the tie molecule is extremely reduced. For this reason, it is very difficult to stably carry out high-magnification drawing in the subsequent drawing step, and yarn breakage and fluff frequently occur, and the whitening phenomenon and strength reduction of the fiber occur. Only when the undrawn yarn is taken up at a take-up speed of 1200 m / min or more, the growth of excessive folding crystals is suppressed by adequately oriented crystallization, so that sufficient tie molecules are present. Thus, it is possible to perform stable drawing with good properties, and as a result, it is possible to obtain a high-strength yarn excellent in quality. Since it is difficult to obtain a high-strength yarn even if the take-up speed is too high, the take-up speed is preferably 4000 m / min or less.
[0020]
In the method for producing an aliphatic polyester multifilament of the present invention, the stretching is performed by multi-stage stretching of two or more stages (stretching stage number: N, N ≧ 2), and further, the stretching ratio of the n-th stage (2 ≦ n ≦ N). Mn satisfies the following formula (1).
(1) 1 ≦ Mn ≦ M_T ^{1 / N}× 1.5
However, M_TIs the total draw ratio (M_T= M₁× M₂× ・ ・ ・ × M_N).
[0021]
If the number of drawing stages is one or two or more, but the draw ratio of each drawing stage does not satisfy the above formula (1), the deformation may be excessively biased in a specific drawing process, When the deformation speed of the film becomes excessively high, good and stable stretchability cannot be obtained, and high strength cannot be achieved. Furthermore, it is preferable that the fiber whitening phenomenon does not occur in any of the drawing stages. Here, the whitening phenomenon of the fiber means a phenomenon in which the fiber becomes cloudy due to separation of voids or a crystal / amorphous structure interface or formation of a fibrillar structure in the fiber internal structure. By preventing the fiber whitening phenomenon from occurring in any of the drawing stages, it is possible to more easily achieve good drawability with less fuzz and yarn breakage, higher strength and superior quality. Aliphatic polyester fibers can be obtained. Further, from the viewpoint that high-stretching can be performed while avoiding fluff, yarn breakage, or fiber whitening, the number of drawing stages is three.It is preferable that
[0022]
Furthermore, in the method for producing an aliphatic polyester multifilament of the present invention, the first stage stretching temperature (T₁) And final stage stretching temperature (T_N) Preferably satisfy the following formulas (2) and (3).
(2) Tg-5 ≦ T₁≦ Tg + 30
(3) Tm-30 ≦ T_N≦ Tm-5
However, Tg is the glass transition point (° C.) of the polymer used for melt spinning, and Tm is the melting point (° C.) of the polymer, which is a value measured by the method described in the examples. By setting the above temperature conditions, the above-described multistage stretching can be performed under better stretchability without fuzz and yarn breakage, and a high-grade fiber having higher strength and no whitening can be obtained. it can. T₁And T_NRespectively refers to the temperature of the stretching apparatus which substantially determines the first stage stretching temperature and the final stage stretching temperature.
[0023]
FIG. 1 shows a drawing process diagram of an example of an embodiment of the present invention. The stretching roller and the relaxing roller in the figure may be non-heated rollers. The draw ratio is determined by the speed ratio of the rollers immediately before and after the contact-type hot plate, and the relaxation rate is determined by the speed ratio of the heat setting roller and the relaxation roller. For example, in the case of two-stage drawing (N = 2), the supplied undrawn yarn is drawn at the first stage and the second stage at the temperature of the contact-type hot plate, respectively, and subsequently heat-treated during the heat setting roller rotation After being further relaxed between the heat setting roller and the relaxing roller, it is wound on a winder. In this case, the temperature of the first contact-type hot plate is T₁In this case, the temperature of the second stage contact type hot plate is T_NIt hits.
[0024]
In the method for producing an aliphatic polyester multifilament of the present invention, the stretching heat source is not limited to the contact-type hot platen, but any method.TakeFor example, a hot roller, a non-contact hot plate, a heat medium bath, or a pin may be used. For exampleIn the case of performing stretching by a hot roller, the process is performed by removing the contact-type hot plate 4 in the stretching process diagram of FIG. At this time, the stretching roller 1 becomes a hot roller, and the hot roller can be provided in multiple stages. In the present invention, such a method can also be suitably used.In the case where the temperature of the first hot roller in the series of roller portions that are substantially stretched is T₁In this case, the temperature of the hot roller that supplies the yarn to the final drawing section is T_NIt hits.
[0025]
Subsequent to stretching, it is preferable to perform heat treatment at a temperature lower by about 10 to 80 ° C. than the melting point of the polymer before winding. Arbitrary methods, such as a hot roller, a contact-type hot plate, and a non-contact type hot plate, can be adopted for the heat treatment. From the viewpoint of dimensional stability, it is preferable that a relaxation treatment of 0 to 20% is performed subsequent to the heat treatment.
[0026]
In order to be widely used as clothing and industrial fibers, the fiber obtained by the method for producing an aliphatic polyester multifilament of the present invention has a strength of 4.5 cN / dtex or more, and further 5.0 cN / dtex or more. Is preferred.
[0027]
In the method for producing an aliphatic polyester multifilament of the present invention, the single filament fineness of the multifilament may be selected according to the use form, but it is usually preferably 1 dtex or more and 22 dtex or less. The total fineness of the multifilament is preferably 20 dtex or more and 3330 dtex or less. Furthermore, the cross-sectional shape is arbitrary, such as round, flat, hollow, Y-type, T-type, and polygonal, but a round cross-section is preferable from the viewpoint of easily achieving high strength.
[0028]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
In addition, the physical property in an Example is the value measured with the following method.
A. Strength (cN / dtex) and elongation (%): Measured under the conditions of a sample length of 25 cm and a tensile speed of 30 cm / min using “Tensilon” tensile tester type manufactured by Orientec Co., Ltd.
B. Melting point (° C.) and glass transition point (° C.): Transition start temperature to a glass state in a measurement at a heating rate of 10 ° C./min using “SSC5200 / DSC120” differential scanning calorimeter manufactured by Seiko Denshi Kogyo Co., Ltd. Was the glass transition point, and the peak temperature of the crystal melting peak was the melting point.
C. Weight average molecular weight: GPC analysis of a 0.1% chloroform solution of the sample was performed, and the weight average value of the dispersion of high molecular weight components excluding components having a molecular weight of 1,000 or less was calculated.
D. Intrinsic viscosity: 8 g of sample was dissolved in 100 ml of orthochlorophenol, and the solution viscosity (η_rp) Was measured at 25 ° C. using an Ostwald viscometer, and the intrinsic viscosity (IV) was calculated by the following approximate expression.
IV = 0.0242η_rp+0.2634
Where η_rp= (T × d) / (t₀Xd₀)
here,
t: Dropping time of solution (second)
t₀: Fall time of orthochlorophenol (seconds)
d: Density of solution (g / cc)
d₀: Orthochlorophenol density (g / cc)
E. Stretchability: According to the state of unstretched yarn being stretched, it was classified and described as follows.
○: There was no whitening phenomenon of yarn breakage, fluff, and drawn yarn, and the drawability was good.
Δ: Some fluff was observed, and some of the whitening phenomenon of the drawn yarn was observed.
X: Many yarn breaks and fluffs, and the whitening phenomenon of the drawn yarn occurred frequently.
XX: Thread breakage occurred frequently and winding was impossible.
F. Biodegradability: The drawn yarn was embedded in activated sludge, and classified and described as follows according to the ratio of the strength after 6 months embedment to the strength before embedment, that is, the strength retention after 6 months.
○: Strength retention is less than 50%.
X: Strength retention is 50% or more.
[0029]
(Examples 1, 3-4, 6 and Comparative Examples 5-7)
L-lactide was mixed with 150 ppm of tin octylate, polymerized in a reaction vessel equipped with a stirrer for 10 minutes at 192 ° C. in a nitrogen atmosphere, further chipped with a twin-screw kneading extruder, and then in a nitrogen atmosphere at 140 ° C. Was subjected to solid phase polymerization to obtain a poly L-lactic acid homopolymer (PLLA) having a melting point of 176 ° C. and a weight average molecular weight of 131,000. This PLLA was dried under reduced pressure at 120 ° C. for 12 hours. For extrusion, an extruder-type melt spinning machine is used, melted at a spinning temperature of 240 ° C., and has a length of 300 mm immediately after spinning and a temperature of 260 ° C. After passing through the atmosphere in the heating cylinder, passing through the annular chimney, cooling with a chimney wind of 20 m / min. Rolled up. In each of the examples and comparative examples, the undrawn yarn was drawn using the apparatus shown in FIG. 1 with the number of drawing stages, the draw ratio, and the drawing temperature (the hot plate temperature in FIG. 1) as described in Table 1. Subsequently, heat setting was performed at a temperature of 155 ° C., a relaxation treatment of 0.5% was performed, and the drawn yarn was wound at a winding speed of 320 m / min. The above-described biodegradability evaluation was performed using this drawn yarn.
Table 1 shows the strength of the drawn yarn, the drawability during drawing, and the biodegradability.
[0030]
[Table 1]

[0031]
(Example 2)
L-lactide is mixed with lactide (racemate) consisting of L-lactic acid and D-lactic acid and polymerized to obtain a D-form copolymerization ratio of 5 mol% poly L-lactic acid copolymer having a melting point of 155 ° C. and a weight average molecular weight of 115,000. Coalescence was obtained. Except for melt spinning using this polymer, yarn was produced in the same manner as in Example 1, and the undrawn yarn was drawn at the drawing stage number, draw ratio, and drawing temperature described in Table 1, whereby both of the D bodies were drawn. A drawn yarn composed of a poly L-lactic acid copolymer (P (L / D) LA) having a polymerization rate of 5 mol% was obtained. The drawn biodegradability was evaluated using this drawn yarn.
Table 1 shows the strength of the drawn yarn, the drawability during drawing, and the biodegradability.
[0032]
(Examples 5, 7-8)
By performing yarn production in the same manner as in Example 1 except that the winding speed of the undrawn yarn was set at 2200 m / min, the undrawn yarn was drawn at the drawing stage number, draw ratio, and drawing temperature described in Table 1 to obtain PLLA. A drawn yarn consisting of The drawn biodegradability was evaluated using this drawn yarn.
Table 1 shows the strength of the drawn yarn, the drawability during drawing, and the biodegradability.
[0033]
Example 9
By setting the polymerization temperature of L-lactide to 198 ° C., the polymerization time to 15 minutes, and the solid-phase polymerization temperature to 147 ° C., PLLA having a melting point of 178 ° C. and a weight average molecular weight of 1870,000 was obtained. Spinning was carried out in the same manner as in Example 1 except that the winding speed of the undrawn yarn was 2200 m / min, and the undrawn yarn was drawn at the number of draw stages, draw ratio, and draw temperature as shown in Table 1. To obtain a drawn yarn made of PLLA. The drawn biodegradability was evaluated using this drawn yarn.
Table 1 shows the strength of the drawn yarn, the drawability during drawing, and the biodegradability.
[0034]
(Comparative Example 1)
Polyethylene terephthalate (PET) having a melting point of 256 ° C. and an intrinsic viscosity of 1.02 was dried under reduced pressure at 130 ° C. for 12 hours, and then melt-spun. A die having 96 annular 3-row holes and 96 0.6φ discharge holes was used, and an extruder type melt spinning machine was used for extrusion. Under the above conditions, the above PET is used for melt spinning at a spinning temperature of 295 ° C., and after passing through an atmosphere in a heating cylinder having a length of 300 mm and a temperature of 320 ° C. immediately after spinning, passes through a circular chimney. After cooling with a chimney wind of 13 m / min and applying an oil agent, the undrawn yarn of 3330 dtex / 96 fil was wound up by taking up at a speed of 1500 m / min. The undrawn yarn was drawn at the drawing stage number, draw ratio, and drawing temperature as described in Table 1, followed by heat setting at a temperature of 155 ° C. and 0.5% relaxation treatment, and a winding speed of 320 m / min. The drawn yarn was wound up at. The above-described biodegradability evaluation was performed using this drawn yarn.
Table 1 shows the strength of the drawn yarn, the drawability during drawing, and the biodegradability.
[0035]
(Comparative Example 2)
By setting the polymerization temperature of L-lactide to 180 ° C., the polymerization time to 6 minutes, and the solid-phase polymerization temperature to 130 ° C., PLLA having a melting point of 176 ° C. and a weight average molecular weight of 79,000 was obtained and melted using this polymer Except for spinning, yarn was produced in the same manner as in Example 1, and an undrawn yarn was drawn at the number of drawing stages, the draw ratio, and the drawing temperature as described in Table 1 to obtain a drawn yarn made of PLLA. It was. The drawn biodegradability was evaluated using this drawn yarn.
Table 1 shows the strength of the drawn yarn, the drawability during drawing, and the biodegradability.
[0036]
(Comparative Example 3)
Polybutylene succinate (PBS) having a melting point of 112 ° C. and a weight average molecular weight of 14,000 was dried under reduced pressure at 80 ° C. for 12 hours, and then melt-spun. A die having 96 annular 3-row holes and 96 0.6φ discharge holes was used, and an extruder type melt spinning machine was used for extrusion. Under the above conditions, the above polybutylene succinate was used for melt spinning at a spinning temperature of 180 ° C., and after passing through an atmosphere in a heating cylinder having a length of 300 mm and a temperature of 200 ° C. immediately after spinning, After passing through the chimney and cooling with a chimney wind at a wind speed of 25 m / min to give an oil, an undrawn yarn of 3330 dtex / 96 fil was wound up by taking it up at a speed of 1500 m / min. The undrawn yarn was drawn at the drawing stage number, draw ratio, and drawing temperature described in Table 1, followed by heat setting at a temperature of 155 ° C., relaxation treatment of 0.5%, and a winding speed of 320 m / min. The drawn yarn was wound up. The above-described biodegradability evaluation was performed using this drawn yarn.
Table 1 shows the strength of the drawn yarn, the drawability during drawing, and the biodegradability.
[0037]
(Comparative Example 4)
By performing yarn production in the same manner as in Example 1 except that the winding speed of the undrawn yarn was set to 750 m / min, and by drawing the undrawn yarn at the number of draw stages, draw ratio, and draw temperature as described in Table 1. A drawn yarn made of PLLA was obtained. The drawn biodegradability was evaluated using this drawn yarn.
Table 1 shows the strength of the drawn yarn, the drawability during drawing, and the biodegradability.
[0038]
【The invention's effect】
By the method for producing an aliphatic polyester fiber of the present invention, even in high-strength stretching, it is possible to perform stable stretching with very little fuzz and yarn breakage, good stretchability, and efficient production at low cost. . The resulting aliphatic polyester fiber has high strength and is extremely excellent in quality without fluff and whitening, and is widely suitable and useful for clothing and industrial use.
[0039]
Furthermore, these fibers are highly biodegradable in the natural environment and have the advantage that they are easily degraded in the natural environment after use. In addition, the degradability can be arbitrarily controlled by changing the design of the fabric or product by the fineness and fiber structure of the fibers used, or the weaving design or coating.
[Brief description of the drawings]
FIG. 1 is a drawing showing an example of an embodiment of the present invention.
[Explanation of symbols]
1: Stretching roller
2: Heat set roller
3: Relaxing roller
4: Contact hot plate
5: Winder
6: Yarn path guide roller
7: Swing arm
8: Yarn feeding section

Claims (4)

An aliphatic polyester polymer mainly composed of polylactic acid mainly composed of L-lactic acid and / or D-lactic acid having a weight average molecular weight of 100,000 to 400,000 was melt-spun and taken up at a take-up speed of 1200 to 2200 m / min . Thereafter, when performing two-stage or three-stage multistage drawing, the draw ratio Mn of the nth stage (1 ≦ n ≦ N) satisfies the following formula (1).
(1) 1 ≦ Mn ≦ M _T ^{1 / N} × 1.5
However, M _T is the total draw ratio (M _T = M ₁ × M ₂ ×... × M _N ), and N is the number of draw stages (N ≧ 2). The method for producing an aliphatic polyester multifilament according to claim 1 , wherein the take-up speed is 1800 m to 2200 m / min . The method for producing an aliphatic polyester multifilament according to claim 1 or 2, wherein the polylactic acid has a weight average molecular weight of 100,000 to 1870,000. The production of the aliphatic polyester multifilament according to any one of claims 1 to 3, wherein the first stage stretching temperature (T ₁ ) and the last stage stretching temperature (T _N ) satisfy the following formulas (2) and (3), respectively. Method.
(2) Tg-5 ≦ T ₁ ≦ Tg + 40
(3) Tm-30 ≦ T _N ≦ Tm-5
However, Tg is the glass transition point (° C.) of the polymer used for melt spinning, and Tm is the melting point (° C.) of the polymer.

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