JP2005206991A - Polylactic acid multi-filament for fiber separation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid multi-filament having excellent fiber-forming property, fiber-separating property and weaving property, stably and at a low cost. <P>SOLUTION: This polylactic acid multi-filament is provided by having ≥3.0 cN/dtex breaking strength, without containing inorganic particles and having ≤0.130 dynamic frictional coefficient between fiber to fiber each other, ≥4 and ≤10 number of single fibers constituting the filament and ≥80 L value of its color tone. The filament is suitable for woven or knitted fabrics to be used as a material for living, hygienic material and clothing material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polylactic acid multifilament for splitting, and more particularly to a polylactic acid multifilament for splitting that can be split with high productivity in a splitting process.

  In recent years, in order to prevent industrial waste from polluting the environment, the use of biodegradable materials has attracted attention, and among these, biodegradable fibers made of polylactic acid polymers have attracted attention.

In particular, tea bags and draining nets have been proposed to impart a biodegradable function in consideration of the environment. Monofilaments are used for tea bags and draining nets because of the required dimensional stability, extraction performance, and draining performance. For example, there is a method of obtaining a polylactic acid monofilament by melt-spinning polylactic acid having an L-form ratio of 95.0 or more and 99.5% or less and then heat-treating it at a draw ratio of 2.8 (see Patent Document 1). , Monofilaments that are not split filaments are used, and not only cannot be industrially manufactured at low cost because they are produced as monofilaments from the spinning stage. Since the discharge amount per nozzle | cap | die fell, there existed a problem that melt | dissolution residence time became long and the thread breakage in the yarn making process by heat deterioration occurred frequently. Some drainage nets use polylactic acid multifilaments (see Patent Document 2). However, since multifilaments are used, sufficient extraction performance as a tea bag cannot be obtained, and there is a problem that drainage performance is insufficient in a draining net.
Polylactic acid multifilaments for splitting can be used as monofilaments by splitting, so that sufficient draining performance can be obtained compared to multifilaments, and it can be manufactured at a lower cost than making monofilaments. is there. However, since polylactic acid fibers have the characteristics that the coefficient of friction is high and the wear resistance is low in the first place, there is a problem of inducing splitting of yarns by rubbing single yarns in the splitting process. However, it was difficult to produce polylactic acid multifilament for splitting.
For example, when the manufacturing method described in Patent Document 1 described above is applied, the preheating temperature at the time of stretching is 85 ° C. and the stretching ratio is 2.8 times, and thus the surface morphology of the obtained polylactic acid fiber is considered to be smooth. The dynamic friction coefficient between single yarns exceeds 0.130, and it is not possible to separate the fibers with good processability in the fiber separation process. Moreover, since the preheating temperature at the time of drawing is 95 ° C. and the draw ratio is 2.0 times when the method shown in Patent Document 2 is applied, it is considered that the surface form of the polylactic acid fiber is similarly smooth, and between the single yarns. The dynamic friction coefficient exceeds 0.130, and it cannot be separated with good processability in the separation process.
JP 2001-131826 A JP 2002-145401 A

  An object of the present invention is to provide a polylactic acid multifilament for splitting that is suitable for use in woven and knitted fabrics for use in living materials, sanitary materials, and clothing materials.

  A polylactic acid multifilament for splitting, having a breaking strength of 3.0 cN / dtex, no inorganic particles, and a yarn / yarn dynamic friction coefficient between single yarns of 0.130 or less.

  The present invention stabilizes polylactic acid multifilaments for splitting having excellent process passability in subsequent splitting and weaving processes by setting the breaking strength and the yarn / yarn dynamic friction coefficient between single yarns to the optimum ranges.・ Provided at low cost.

  Hereinafter, the present invention will be described in detail.

  The polylactic acid multifilament for splitting in the present invention is required to have a strength of 3.0 cN / dtex or more. If the strength of the polylactic acid multifilament for splitting is less than 3.0 cN / dtex, yarn breakage frequently occurs in the splitting process, and it is impossible to weave with high productivity in the weaving process. More preferably, it is 3.3 cN / dtex or more.

  It is important that the polylactic acid used in the polylactic acid multifilament for fiber separation of the present invention does not contain inorganic particles. If inorganic particles are contained in the fiber, the inorganic particles may contaminate the soil after decomposition in the soil. Further, the yarn / yarn dynamic friction coefficient between single yarns needs to be 0.130 or less. When the yarn / yarn dynamic friction coefficient between single yarns exceeds 0.130, yarn breakage occurs frequently due to the yarns rubbing in the fiber separation process, and this is not the subject of the present invention.

  The single yarn fineness of the polylactic acid multifilament for splitting in the present invention is preferably 15 dtex or more and 40 dtex or less. Generally, in the splitting process, an average splitting tension of 30 cN is applied to the single yarn, and in order to stably split in consideration of the tension fluctuation in the splitting process, the absolute strength of the single yarn, that is, the single yarn fineness and the fiber strength Is preferably 45 cN or more. That is, if the single yarn fineness is 15 dtex or more and the strength of the present invention is 3.0 cN / dtex, the single yarn absolute strength is 45 cN or more, and it is preferable because the yarn can be divided more stably without breaking the yarn in the division step. . Further, when the single yarn fineness is high, there is a problem in that the package form is drum or cheese, and there is a problem that yarn dropping frequently occurs and the yarn breaks. Therefore, the single yarn fineness in the present invention is preferably 40 dtex or less.

  The polylactic acid multifilament for splitting of the present invention is preferably in the range of 4 to 10 single yarns. When the number of single yarns is small, the productivity decreases and it becomes difficult to produce polylactic acid fibers industrially at low cost, and the discharge amount of the polylactic acid polymer per die during melt spinning decreases, The melt residence time becomes long, and there is a risk of inducing yarn breakage in the yarn making process due to thermal deterioration, yarn breakage and fluffing during the fiber separation process. In addition, when the number of single yarns is large, entangled portions are generated during running of the yarn due to the high yarn / inter-yarn friction that is the original characteristic of polylactic acid fibers, which only induces uneven drawing and uneven heat treatment between single fibers. In addition, thread breakage may occur frequently during the subsequent splitting process. Moreover, since the quality becomes inferior when the woven or knitted fabric is formed from the drawing unevenness between the single fibers and the heat treatment unevenness, the number of single yarns in the present invention is preferably 4 to 10. Further, considering the uniformity of quality and physical properties and industrially stable production, the more preferable number of single yarns is 6-8.

  The color tone L value of the polylactic acid multifilament for splitting of the present invention is preferably 80 or more. The color tone L value of the polylactic acid fiber is a value that varies depending on the fiber surface state. A polylactic acid fiber having a color tone L value of less than 80 has a smooth fiber surface, a high coefficient of friction, and a polylactic acid fiber originally having low wear resistance may induce thread breakage in the fiber separation process. A polylactic acid fiber having a color tone L value of 80 or more is preferable because moderate irregularities are present on the fiber surface, so that the friction coefficient is low and excellent wear resistance is obtained. Also, if the color tone L value exceeds 97, the unevenness of the fiber surface becomes excessive, cracks may occur in the fiber, and the strength of the fiber may be reduced, and the friction coefficient and strength that can be more stably separated in the separation process In order to obtain the above, the color tone L value is more preferably 85 or more and 97 or less.

Hereinafter, the present invention will be described in detail with reference to examples. The evaluation in the examples followed the following method.
1. Total fineness (dtex)
Using a measuring machine manufactured by Asano Kikai Co., Ltd., the obtained multifilament was sampled 1000 m, the weight was measured, and the weight value converted to 10,000 m was defined as the fineness.
2. Single yarn fineness (dtex)
The multifilament is disassembled into single yarns, and the single yarns are converted into SEACH CO. Measurement was performed using a DENIER COMPUTER made by LTD under a load of 1/10 of the fineness of the multifilament with a sample length of 5 cm.
3. Yarn / yarn dynamic friction coefficient After splitting into single yarn, it is passed through a pulley with a diameter of 35 mm at a yarn speed of 55 m / min, contact angle 90 °, pulley twist twice, pulley entry side tension: T1 = 10, measurement temperature 20 ° C Under conditions of ± 5 ° C. and humidity 60% RH ± 10%, the pulley exit side tension: T2 was measured for 30 seconds, and the yarn / yarn friction coefficient was calculated by the following equation. For the measurement of the tension, an HS4000μ type tension meter manufactured by Eiko Sangyo Co., Ltd. was used for both T1 and T2.
Yarn / yarn dynamic friction coefficient = 0.4697 x Log (T2 / T1)
4). Breaking strength (cN / dtex), elongation at break (%)
Multifilaments were measured using a TENSILON / UTM-III-100 manufactured by TOYO BALDWIN under the measurement conditions of a sample length of 20 cm and a tensile speed of 20 cm / min.
5). Color tone L value The surface of a measurement sample obtained by winding 5 g of a product on an aluminum plate at 6.0 cm × 4.5 cm is measured with a SM color computer manufactured by Suga Test Instruments under 0-d ° illumination and light receiving conditions, and displayed as Hunter Lab. It was displayed as the L value of the L, a, and b values of the system.
6). Thread-making properties 100 pieces of cheese-like package of 10 kg of product, that is, less than 5 times of yarn breakage from the number of yarn breaks that occurred until 1,000 kg of product was completed, △, 10 times less than 10 times The number of times was set as x, and ◯ and Δ were set as pass.
7). Splitting properties Using a Kanda Giken straight splitting machine, 10 full polylactic acid multi-filament cheese-shaped packages for splitting 10 kg of full-pipe products are used as parent yarns and split into 1 kg per filament at a speed of 200 m / min. The split filament yarn full ratio was 85% or more, ○ was 75% or more and less than 85%, Δ was less than 75%, and ○ and Δ were acceptable.

Example 1
Spinning temperature 230 using a poly-L-lactic acid polymer 6201D (number average molecular weight 84,000, optical purity 97.8%) manufactured by Cargill Dow Co., Ltd. with a one-stage drawing type direct spinning drawing machine shown in FIG. The yarn melted and discharged at a discharge rate of 97 g / min per spinneret from a spinneret having a discharge hole number of 10 at ℃ is cooled and passed through a stretch roller with a surface speed of 980 m / min, and then a surface temperature of 75 ° C. and a surface speed of 1000 m / min. The first hot roller for 1 minute, the second hot roller with a surface temperature of 120 ° C. and the surface speed of 3400 m / minute, after preheating and drawing heat treatment, with a winding tension of 0.1 cN / dtex, polylactic acid multi-fiber for separation The filament was wound into a cheese-like package.

  The obtained fiber had a single fiber fineness of 27 dtex, a single yarn number of 10, a strength of 3.6, a yarn breakage number of 2 times, a split filament yarn fullness of 94%, and good yarn-making and splitting properties. .

Example 2
The polylactic acid multifilament for separation was wound up in the same manner as in Example 1 except that the number of discharge holes of the base was set to 4 and the discharge amount per base was set to 39 g / min. The number of thread breaks was 9 and the split fiber width was 89%. Both the yarn-making property and the splitting property were good.

Example 3
The polylactic acid multifilament for splitting is wound in the same manner as in Example 1 except that the discharge amount per die is 150 g / min so that the single yarn fineness of the resulting polylactic acid multifilament for splitting is 40 dtex. I took it. Although yarn breakage occurred due to yarn dropping during unwinding in the splitting process, the split split full winding rate is 85%, and there is no problem in actual production and good splitting. It was sex.

Example 4
The polylactic acid multifilament for splitting is wound in the same manner as in Example 1 except that the discharge amount per mouthpiece is 56 g / min so that the single yarn fineness of the obtained polylactic acid multifilament for splitting is 15 dtex. I took it. Yarn breakage occurred due to an increase in the melt residence time of the polylactic acid polymer due to a decrease in the polymer discharge amount per die, but the number of thread breakage was 8 times, and it was thought to be caused by fluctuations in the splitting tension. Although splitting yarn breakage occurred, the splitting yarn full tube rate was 80%, and both the yarn-making property and the splitting property were at a level with no problem.

Example 5
The polylactic acid multifilament for splitting is wound up in the same manner as in Example 1 except that the surface speed of the second hot roller is changed so that the color tone L value of the resulting polylactic acid multifilament for splitting becomes 95. It was. The number of yarn breaks was 3 times, and the full fiber split ratio of the split filament yarn was improved to 98% due to a decrease in the friction coefficient.

  The results of Examples 1 to 5 are summarized in Table 1.

Comparative Example 1
Winding the polylactic acid multifilament for splitting in the same manner as in Example 1 except that the surface speed of the second hot roller was changed so that the strength of the resulting polylactic acid multifilament for splitting was 2.6 cN / dtex I took it. Although there was no problem with the yarn-splitting property with 5 yarn breaks, the splitting of the split yarn frequently occurred due to the decrease in strength, and 1 kg of the full-length splitting yarn could not be collected at all.

Comparative Example 2
The polylactic acid multifilament for splitting was wound up in the same manner as in Example 1 except that the first hot roller temperature was changed so that the color tone L value of the obtained polylactic acid multifilament for splitting was 75. Although the number of yarn breaks was 7 and the spinning performance was not a problem, the surface of the polylactic acid multifilament for splitting was excessively smooth, so the yarn / yarn dynamic friction coefficient between single yarns was 0.141, and the splitting process As a result, the splitting of the split yarn, which seems to be caused by the rubbing of the yarns, occurred frequently, and 1 kg of the full-split yarn was not obtained at all.

Comparative Example 3
The polylactic acid multifilament for splitting was wound up in the same manner as in Example 1 except that the number of discharge holes of the die was set to 2 and the discharge amount per die was 19 g / min. The yarn breakage due to thermal deterioration due to the remarkable increase in the polymer residence time accompanying the decrease in the polymer discharge amount per die was frequent, and the number of yarn breaks was 24, which was a level that could not be produced. The resulting polylactic acid multifilament for splitting had a single fiber fineness of 26 dtex and a split fiber fullness of 73%, which was a level that could not be produced.

Comparative Example 4
The polylactic acid multifilament for separation was wound up in the same manner as in Example 1 except that the number of discharge holes of the die was set to 14 and the discharge amount per die was set to 136 g / min. Although the number of yarn breaks was 3 and there was no problem in yarn production, the split filament yarn full tube rate was 70%, which was a level that could not be substantially produced.

Comparative Example 5
The polylactic acid multifilament for splitting is wound in the same manner as in Example 1 except that the discharge amount per cap is 45 g / min so that the single yarn fineness of the resulting polylactic acid multifilament for splitting is 12 I took it. The yarn breakage due to thermal deterioration due to the remarkable increase in the polymer residence time accompanying the decrease in the polymer discharge amount per die frequently occurred, and the number of yarn breaks was 18 times, which was a level that could not be substantially produced. Further, in the splitting, the splitting tension could not be endured, the yarn breakage occurred frequently, and even if the splitting speed was reduced to 100 m / min, it was not improved, and a full pipe 1 kg of splitting yarn was not obtained at all. .

Comparative Example 6
The polylactic acid multifilament for splitting was wound up in the same manner as in Example 1 except that the discharge amount per die was 205 g / min. The obtained polylactic acid fiber had a single fiber fineness of 50 dtex, frequent thread breakage that was attributed to a marked decrease in cooling uniformity, and the number of thread breaks was 16. Also, in the splitting and weaving processes, the broken bobbin package collapses and the fabric texture collapses due to thread breakage that seems to be due to uneven physical properties in the longitudinal direction of the fibers and excessive rigidity due to the increase in single fiber fineness. Was generated, and the splitting yarn full pipe ratio was 71%, which was a level that could not be substantially produced.

  Table 1 summarizes the results of Examples 1 to 5 and Comparative Examples 1 and 2.

Schematic of a single-stage drawing type direct spinning drawing machine that can be used in the present invention

Explanation of symbols

1: base 2: cooling device 3: stretch roller 4: first hot roller 5: second hot roller 6: cheese package

Claims (3)

  A polylactic acid multifilament for splitting having a breaking strength of 3.0 cN / dtex or more, no inorganic particles, and a yarn / yarn dynamic friction coefficient between single yarns of 0.130 or less.   The polylactic acid multifilament for splitting according to claim 1, wherein the number of single yarns constituting the multifilament is 4 or more and 10 or less, and the single yarn fineness is 15 dtex or more and 40 dtex or less.   The polylactic acid multifilament for splitting according to claim 1 or 2, wherein the color tone L value is 80 or more.

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