JP2006188799A - Polylactic acid false-twist textured yarn package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid false-twist textured yarn package slight in developing the crimp alteration and mechanical strength drop with time of the polylactic acid false-twist textured yarn, affording good weavability/knittability and enabling high-grade woven/knitted fabrics to be obtained. <P>SOLUTION: The package is such that the polylactic acid false-twist textured yarn is wound in the form of a cheese. This package has a wound density of 0.3-0.6 g/cm<SP>3</SP>and is characterized by that the mechanical strength retention of the false-twist textured yarn is 70-100%, wherein the mechanical strength retention (%) is defined by (B/A)×100 [wherein, A is the mechanical strength of the false-twist textured yarn determined immediately after unreeling it from the package, and B is the mechanical strength of the false-twist textured yarn determined immediately after unreeling it from the above package which is left to stand for 3 months under the standard conditions (20°C, 65% RH)]. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a package made of a polylactic acid false twisted yarn, and more specifically, a polylactic acid false twist capable of obtaining a good knitting property and an excellent quality woven or knitted fabric with little change in strength over time. It relates to a processed yarn package.

  In recent years, polylactic acid fibers have been used for clothing and industrial materials as low environmental impact materials because of their excellent biodegradability and plant-derived materials.

  In general, thermoplastic fibers such as polyethylene terephthalate and nylon are generally subjected to false twisting by a method such as friction false twist and spindle false twist to give crimp. However, polylactic acid is significantly different from polyethylene terephthalate and nylon in polymer characteristics, has a low melting point and remarkably softens upon heating, so that conventional conditions cannot be employed as they are.

  Usually, the false twisting temperature of polylactic acid fiber is about 80 to 100 ° C. when the processing speed is 100 m / min. For this reason, the false twisted yarn obtained has low crimp fastness, that is, the change in crimp characteristics over time is large, and when wound under the same conditions as polyester, the crimp decreases with time and the strength decreases. It will be remarkable. When such a change with time occurs, in the case of knitting and weaving, since the fibers wound in several types of packages are used, the strength and crimp of the fibers constituting the woven or knitted fabric become uneven, There was a problem that the quality of the obtained woven or knitted fabric was lowered.

  In the invention described in Patent Document 1, it is proposed to obtain a polylactic acid false-twisted yarn having a small shrinkage after hydrothermal treatment, high crimpability, and high quality by using specific drawing false twist conditions. ing.

However, in the polylactic acid false twisted yarn described in Patent Document 1, a highly crimped false twist yarn could be obtained. However, focusing on only the drawn false twist conditions, the winding conditions were the same as those for ordinary polyester fibers. Therefore, crimping and strength are reduced with time, and the quality of the product when it is made into a woven or knitted fabric cannot be improved.
Japanese Patent Laid-Open No. 2002-285438

  The present invention solves the problems as described above, the change of crimp of polylactic acid false twisted yarn over time, the occurrence of reduced strength is less, good knitting properties are obtained, and excellent An object of the present invention is to provide a polylactic acid false twisted yarn package capable of obtaining a quality woven or knitted fabric.

  As a result of investigations to solve the above problems, the present inventors have reached the present invention.

That is, the present invention is a package in which false twisted yarn obtained by false twisting polylactic acid fiber is wound into a cheese shape, and the winding density is 0.3 to 0.6 g / cm ^3. The gist of the polylactic acid false twisted yarn package is characterized in that the strength retention of the false twisted yarn indicated by is 70 to 100%.
Strength retention (%) = (B / A) × 100
However, A is the strength measured immediately after unwinding the false twisted yarn unwound from the package. B shows the strength measured immediately after unwinding the false twisted yarn in the same manner as A after leaving the package measured in A in the standard condition (temperature 20 ° C, humidity 65%) for 3 months. .

  According to the polylactic acid false twisted yarn package of the present invention, since the wound polylactic acid false twisted yarn has little change in crimp over time, the strength is less reduced, so that good weaving properties can be obtained and excellent quality can be obtained. It becomes possible to obtain a woven or knitted fabric.

  Hereinafter, the present invention will be described in detail.

  The polylactic acid constituting the polylactic acid fiber in the present invention is preferably one having L-lactic acid or D-lactic acid as the main repeating unit, and is a copolymerized polylactic acid obtained by copolymerizing other components having ester forming ability. There may be. Among these, from the viewpoint of achieving a high melting point, a copolymer or mixture in which the ratio of L-lactic acid to D-lactic acid is (L-lactic acid) / (D-lactic acid) = 95/5 to 100/0 in terms of molar ratio is preferable. .

  Further, in the polylactic acid, an inorganic material such as a matting agent, a plasticizer, an antioxidant, an ultraviolet absorber, a deodorant, a color pigment, or an organic compound can be added as necessary.

  The polylactic acid false twisted yarn in the present invention is a polylactic acid fiber subjected to false twisting, but the conditions of false twisting are not particularly limited. For example, false twisting with a false twist pin or a friction disk. The thing which processed is mentioned.

Generally, the polylactic acid false twisted yarn has a significant decrease in strength over time, and as a result of various investigations on the causes thereof, the present inventors have found that the polylactic acid false twisted yarn is weak against continuous stress load, and the stress is low. It has been found that the higher the strength, the more the strength decreases. That is, by reducing the winding tension as much as possible and lowering the winding density, the decrease in strength can be reduced. In addition, as described above, the polylactic acid false twisted yarn has a low crimp fastness and is crimped. It is important to reduce the winding density from the viewpoint of reducing the change with time of characteristics. Therefore, the polylactic acid false twisted yarn package of the present invention preferably has a winding density of 0.3 to 0.6 g / cm ³ , and more preferably 0.3 to 0.5 g / cm ³ .

When the winding density exceeds 0.6 g / cm ³ , the effects as described above cannot be achieved, and the strength reduction and crimp reduction with time increase. On the other hand, if it is less than 0.3 g / cm ³ , unsatisfactory unraveling tends to occur.

  The winding density in the present invention is measured as follows. A value R obtained by subtracting the mass of the paper tube from the mass of the entire package is divided by the volume Q of the wound portion of the yarn. Note that the volume Q of the winding portion of the yarn is such that the shape of the package is as shown in FIG. 2, so that the winding points A, B, G, H of the yarn and the points C, D, E of the end of the package are as follows. , F is used to measure the length of each line segment (ignoring bulges and ear heights and measuring the length as a straight line), and calculating the volume Q of the wound portion of the yarn from these lengths. (The volume of the paper tube 7 is excluded).

And as for the package of this invention, the strength retention of the wound twisted yarn is 70 to 100%, and it is preferable that it is 80 to 100% especially.
This strength retention is an index indicating that the decrease in strength over time is small. In the present invention, the strength retention rate is around 3 months, regardless of how much time has passed since winding. By looking at the change in strength, the change over time in the strength of the wound false twisted yarn is observed.

  If the strength retention is less than 70%, the wound false twisted yarn has a decrease in strength over time. When a woven or knitted fabric is used, a large number of packages are used. If the package is wound, the knitting and knitting properties are inferior, and an excellent quality woven or knitted fabric cannot be obtained. In addition, since it is preferable that the strength of the false twisted yarn after the elapse of 3 months is not lower than that of the yarn before 3 months, the upper limit of the retention rate is 100%.

  Further, the strength of the polylactic acid false twisted yarn wound around the package of the present invention (strength measured immediately after unwinding from the package) is preferably 1.8 cN / dtex or more, and in particular, 2.0 to It is preferably 5.0 cN / dtex. When the strength is less than 1.8 cN / dtex, fluff is likely to occur during weaving or in the preparation process, and the process passability is reduced. Moreover, from the viewpoint of polymer characteristics, production conditions, etc., the strength exceeding 5.0 cN / dtex tends to be disadvantageous in terms of cost.

  Moreover, it is preferable that the expansion / contraction rate of the polylactic acid false twisted yarn wound around the package of the present invention is 35% or more, and considering the polymer characteristics, production conditions, etc., it is 35-60%. It is preferable. If the stretch / elongation rate is less than 35%, the resulting knitted or knitted fabric has poor swell and stretch properties. On the other hand, in order for the expansion / contraction elongation ratio to exceed 60%, excessive heat treatment is required, and as a result, the strength tends to be low and brittle.

  The stretch / elongation rate means that the false twisted yarn is unwound and taken out from the package, left in a standard state (temperature 20 ° C., humidity 65%) for 24 hours, heat-treated in boiling water for 30 minutes, and then air-dried. The sample lengths L1 and L2 are measured according to JIS L-1013 stretch A method, and the stretch elongation rate (%) is calculated by the following formula.

Expansion / contraction elongation = [(L2-L1) / L1] × 100
L1 is the sample length (mm) after 30 seconds with a load of 0.176 mN × display tex number applied to the sample, and L2 is the sample length (mm) after 30 seconds with a load of 8.82 mN × display tex number applied. is there. The measurement is performed three times and expressed as an average value.

  Next, the manufacturing method of the polylactic acid false twisted yarn package of the present invention will be described using an example. FIG. 1 is a schematic process diagram showing one embodiment of an apparatus suitable for carrying out the present invention. Reference numeral 1 denotes a yarn feeding roller, 4 denotes a first take-up roller, and 5 denotes a second take-up roller. A first heater 2 and a twisting device 3 are provided between these rollers. The twist imparted to the supply yarn Y by the twisting device 3 goes back along the supply yarn Y toward the yarn feeding roller 1. The twist retroactively along the supply yarn Y is heat-fixed by the first heater 2 and the actual twist is imparted to the supply yarn Y. The supply yarn Y to which the actual twist is imparted by the first heater 2 is untwisted when it next exits the twisting device 3, and is fed from the first take-up roller 4 to the take-up device 6 via the second take-up roller 5. Be sent. At this time, if necessary, an interlacer is provided between the first take-up roller 4 and the second take-up roller 5 to impart entanglement to the yarn to improve the convergence of the yarn, or to the second heater at the same position. Can be added to reduce the yarn torque.

  And in the winding device 6, it can be set as the package of the winding density prescribed | regulated by this invention by adjusting the winding tension | tensile_strength at the time of winding, ie, an overfeed rate, and a traverse angle suitably. A preferable range of the twill angle is 12 to 17 degrees. When the twill angle is less than 12 degrees, a so-called bulge that the end face of the package swells becomes tight, and it is easy to cause collapse or twill. If the twill angle exceeds 17 degrees, both ends of the package side face become so-called ear height, and the winding hardness of the ear high portion becomes extremely hard, and there is a tendency to cause release failure and deterioration of the quality of the yarn.

Next, the present invention will be described more specifically with reference to examples. In addition, the measuring method and evaluation method in an Example and a comparative example were performed with the following method.
(1) Winding density It measured and calculated by the said method.
(2) Strength Unwinding and taking out false twisted yarn from the obtained package (immediately after false twisting), obtaining a positive fineness according to JIS L-1013, and following a standard time test of tensile strength, Shimadzu Using an autograph AGS-5KNG manufactured by Seisakusho, measurement was performed at a sample length (grip interval) of 20 cm and a pulling speed of 20 cm / min.
(3) Strength retention rate It measured and calculated by the said method. The strength was measured by the method (2) above.
(4) Stretch / elongation rate It measured and calculated by the said method.
(5) Unraveling property Evaluated by the number of stops when 5 packages (3 kg roll) obtained were unwound at 500 m / min. X.
(6) Fabric quality A smooth knitted fabric is produced using 30 of the obtained packages (3 kg roll), dyeing is performed in a conventional manner, and the surface quality is visually determined. ○: Good, Δ: Somewhat Evaluation was made in three stages: defective and x-defective.

Examples 1-4, Comparative Examples 1-2
Melting spinning was performed using a chip of polylactic acid (a copolymer of L-lactic acid and D-lactic acid, molar ratio (L / D = 99/1)) having a melting point of 168 ° C. and a number average molecular weight of 72,000, Taking up was performed at a take-up speed of 3200 m / min to obtain a highly oriented undrawn yarn of 110 dtex / 36 fil. Using this highly oriented undrawn yarn as a supply yarn, false twisting was performed under the drawing and false twisting conditions shown in Table 1 according to the steps shown in FIG. The processing speed shown in Table 1 is the speed of the first take-up roller 4, and the stretch ratio is based on the ratio of the speed of the supply roller 1 and the first take-up roller 4 in FIG.
Table 1 shows the characteristics and evaluation of the obtained package.

As is clear from Table 1, the polylactic acid false twisted yarn package of the present invention obtained in Examples 1 to 4 has good unraveling properties and retains the strength of the wound polylactic acid false twisted yarn. Since the rate was also high, a high-quality knitted fabric could be obtained.
On the other hand, since the winding density of the package obtained in Comparative Example 1 was too high, the strength retention of the wound polylactic acid false-twisted yarn was low, and the resulting knitted fabric had a reduced quality. It was. Since the package of Comparative Example 2 had a winding density that was too low, the unwinding property was remarkably poor, and the process passability when obtaining a knitted fabric was poor.

It is a schematic process drawing which shows one embodiment of the manufacturing process of the package of this invention. It is a schematic diagram which shows the calculation method of the winding density of the package of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Yarn supply roller 2 1st heater 3 Twisting device 4 1st take-up roller 5 2nd take-up roller 6 Winding device Y supply yarn 7 Paper tube

Claims (3)

A package in which a false-twisted yarn obtained by subjecting polylactic acid fiber to false twisting is wound into a cheese shape, the winding density is 0.3 to 0.6 g / cm ³ , and the false twisted yarn represented by the following formula A polylactic acid false twisted yarn package characterized by having a strength retention of 70 to 100%.
Strength retention (%) = (B / A) × 100
However, A is the strength measured immediately after unwinding the false twisted yarn unwound from the package. B shows the strength measured immediately after unwinding the false twisted yarn in the same manner as A after leaving the package measured in A in the standard condition (temperature 20 ° C, humidity 65%) for 3 months. . The polylactic acid false twisted yarn package according to claim 1, wherein the stretch elongation rate measured immediately after unwinding the false twisted yarn unwound from the package is 35% or more. The polylactic acid false twisted yarn package according to claim 1 or 2, wherein the polylactic acid fiber is made of polylactic acid containing L-lactic acid as a main component.