JP4803192B2 - Low shrinkage aliphatic polyester fiber and method for producing the same - Google Patents

Description

  The present invention relates to a low shrinkage and thermally stable aliphatic polyester fiber and a method for producing the same. More particularly, the present invention relates to an aliphatic polyester fiber having a very low thermal shrinkage due to a low shrinkage rate of the fiber when a fabric structure is formed, and therefore excellent in processability for high-order processing, and a method for producing the same.

Aliphatic polyester fibers have attracted attention in recent years because of their biodegradability, and are increasingly used for textile applications for clothing. As these aliphatic polyester fibers, poly-ε-caprolactone fibers as found in Patent Document 1 and polybutylene succinate fibers as found in Patent Document 2 are known. However, since polycaprolactone fiber has a melting point as low as about 60 ° C., it cannot pass through a dyeing process, and is not satisfactory as a fiber for clothing. In addition, polybutylene succinate fibers have a melting point as low as about 110 ° C., and the shrinkage rate in hot water at 100 ° C. is extremely large.
JP-A-5-59611 Japanese Patent Laid-Open No. 9-74661

  An object of the present invention is to overcome the above-described problems and provide an aliphatic polyester fiber having a small shrinkage rate in hot water, particularly a shrinkage rate as a fabric structure, and a method for producing the same.

The problem of the present invention described above is that the maximum value of the shrinkage stress is ₀ to 0.2 cN / dtex, and the boiling water shrinkage rate S ₀ under no load and the boiling water shrinkage rate S ₁ under 0.01 cN / dtex load are as follows. The problem can be solved by the aliphatic polyester fiber characterized by satisfying the relationship of the following formulas 1 and 2.
S ₁ ≦ 5 (Formula 1)
S ₁ ≦ S ₀ × 0.8 (Expression 2)
In this case, the aliphatic polyester is a polylactic acid having L-lactic acid and / or D-lactic acid as a main repeating unit, and the ratio of L-lactic acid or D-lactic acid in the polylactic acid is 95 mol% or more. Preferably there is.

  In order to obtain a low-shrinkage aliphatic polyester fiber having these characteristics, in the method for producing an aliphatic polyester fiber in which a running yarn is brought into contact with a heated rotating roller to perform heat setting, the temperature of the rotating roller is set to 100. It is possible to employ a method for producing an aliphatic polyester fiber characterized in that the tension of the running yarn separated from the rotating roller is set to ˜150 ° C. and the tension of the running yarn is 0.2 cN / dtex or less.

  Further, in the method for producing an aliphatic polyester fiber in which the traveling yarn is brought into contact with a heated hot plate to perform heat setting, the temperature of the hot plate is set to 110 to 160 ° C., and the running yarn separated from the hot plate is used. The production method of the aliphatic polyester fiber characterized by setting the tension of the fiber to 0.2 cN / dtex or less can be used.

  Even when these production methods are adopted, the aliphatic polyester is a polylactic acid substantially having L-lactic acid and / or D-lactic acid as a main repeating unit, and the L-lactic acid or D-lactic acid of the polylactic acid. It is preferable to employ a ratio of 95 mol% or more.

  Since the fiber of the present invention has a low shrinkage rate and shrinkage stress, the shrinkage rate as a fabric structure is small. For this reason, the fabric hardly shrinks even by hot water treatment such as scouring and dyeing, it is possible to maintain a soft texture, and since the width is suppressed, the fabric weight can be reduced.

  The fibers in the fabric structure are constrained by adjacent fibers and are in a state where free shrinkage is difficult. However, when the shrinkage stress is higher than 0.2 cN / dtex, the shrinkage force of the fibers in the fabric structure can overcome the restraining force of the adjacent fibers and freely shrink, and the effect of low shrinkage. Cannot be obtained. The aliphatic polyester fiber of the present invention has a maximum shrinkage stress of 0 to 0.2 cN / dtex. In order to obtain low shrinkage characteristics, the shrinkage stress is preferably 0 to 0.1 cN / dtex.

In addition, the aliphatic polyester fiber of the present invention has a boiling water shrinkage ratio S ₀ under no load and a boiling water shrinkage ratio S ₁ under a load of 0.01 cN / dtex satisfy the relationship of the following formulas 1 and 2. is important.
S ₁ ≦ 5 (Formula 1)
S ₁ ≦ S ₀ × 0.8 (Expression 2)
The boiling water shrinkage ratio S ₁ under a load of 0.01 cN / dtex corresponds to the shrinkage ratio of the fibers in boiling water when the fibers exist as a fabric structure such as a woven fabric or a knitted fabric. The S ₁ are those of 5% or less, and more preferably 3% or less.

Since the aliphatic polyester of the present invention has a sufficiently small shrinkage stress, the boiling water shrinkage S ₁ under a load of 0.01 cN / dtex is smaller than the shrinkage S ₀ of the fiber under no load. S ₁ is S ₀ × 0.8 or less, and S ₁ is preferably S ₀ × 0.5 or less for lower shrinkage characteristics.

  The fiber of the present invention comprises an aliphatic polyester. Examples of the aliphatic polyester include polylactic acid, polyglycolic acid, poly-3-hydroxypropionate, poly-3-hydroxybutyrate, and poly-3-hydroxybutyrate varieties. Polyoxyacids such as acrylates, polycondensates of aliphatic dicarboxylic acids and aliphatic diols, polyesters obtained by ring-opening polymerization of aliphatic cyclic esters such as polypivalolactone, and blends and modified products thereof However, the present invention is not limited to these examples. Among these, from the viewpoint of a high melting point and a low shrinkage rate, it is preferably a polylactic acid having L-lactic acid and / or D-lactic acid as a main repeating unit, and the ratio of L-lactic acid or D-lactic acid in the polylactic acid. Is preferably 95 mol% or more.

  The method for producing polylactic acid includes a two-stage lactide method in which L-lactic acid and / or D-lactic acid is used as a raw material to form lactide, which is a cyclic dimer, and then ring-opening polymerization is performed, and L-lactic acid and / or Alternatively, a one-step direct polymerization method in which dehydration condensation is directly performed in a solvent using D-lactic acid as a raw material is known. The polylactic acid used in the present invention may be obtained by any method.

  The average weight molecular weight of polylactic acid is usually at least 50,000, preferably at least 100,000, preferably 100,000 to 300,000. If the average weight molecular weight is lower than 50,000, only fibers having low strength properties can be obtained.

  The melting point of polylactic acid is 100 ° C. or higher, preferably 140 ° C. or higher, and most preferably 160 ° C. or higher. If the melting point is less than 100 ° C, the product quality is extremely low, such as poor stretchability due to the occurrence of fusion between single yarns, and fusing defects during dyeing, heat setting, and friction heating. Therefore, it cannot be used for swimsuit applications. Here, the melting point means the peak temperature of the 1st run melting peak obtained by DSC measurement.

  The polylactic acid in the present invention may be a copolymerized polylactic acid obtained by copolymerizing other components having ester forming ability in addition to L-lactic acid and D-lactic acid. The copolymerizable component includes glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, hydroxycarboxylic acids such as 6-hydroxycaproic acid, ethylene glycol, propylene glycol, butanediol, neo Compounds containing a plurality of hydroxyl groups in the molecule such as pentyl glycol, polyethylene glycol, glycerin and pentaerythritol or derivatives thereof, compounds containing a plurality of carboxylic acid groups in the molecule such as adipic acid, sebacic acid and fumaric acid Or a derivative thereof.

  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. Furthermore, inorganic fine particles and organic compounds can be added as necessary as a matting agent, deodorant, flame retardant, yarn friction reducing agent, antioxidant, coloring pigment, and the like.

  However, in order to maintain a low shrinkage rate, it is preferable that either L-lactic acid or D-lactic acid occupies 95 mol% in the aliphatic polyester polymer.

  Moreover, as for the aliphatic polyester fiber in this invention, it is desirable for the intensity | strength of a fiber to be 2 cN / dtex or more. When the strength is less than 2 cN / dtex, it is not preferable because a yarn breakage stop at the time of weaving or weaving occurs or the strength of the fabric or knitted fabric is reduced, resulting in a decrease in product strength. More preferably, it is 3 cN / dtex or more, and most preferably 4 cN / dtex or more.

The aliphatic polyester fiber according to the present invention is, for example, a method for producing an aliphatic polyester fiber in which a running yarn is brought into contact with a heated rotating roller, and the temperature of the rotating roller is set to 100 to 150 ° C. It can be produced by a method for producing an aliphatic polyester fiber, wherein the tension of the traveling yarn separated from the rotating roller is 0.2 cN / dtex or less. When the temperature is less than 100 ° C., the shrinkage rate may be too high, which is not preferable. The higher the temperature of the heated rotating roller, the lower the fiber shrinkage ratio S ₀ , but at temperatures exceeding 150 ° C., fiber fusion may occur, which is not preferable. The temperature of the heated rotating roller is more preferably 110 to 130 ° C.

  The running yarn can be brought into contact with the rotating roller by contacting the fiber with a part of the circumference of the roller, or by using a heated rotating roller and a separate roller with different axes in combination. It may be circulated. The heated rotating roller may be a mirror surface or may be a satin roller having a rougher surface than the mirror surface.

  Moreover, it is preferable that the tension | tensile_strength of the running yarn after contacting a heating roller is 0.2 cN / dtex or less. When the tension is too high, the shrinkage stress tends to be high, so that the effect of the low shrinkage of the present invention is reduced.

  FIG. 1 is a process diagram showing an example of a method for producing an aliphatic polyester fiber of the present invention. In FIG. 1, the running yarn is supplied at a constant speed by a feed roller 3 and preheated by a preheating roller 4, and is then drawn in a drawing zone 5 with a heat setting means 1 that is a heated rotating roller. The traveling yarn leaving the heat setting means 1 which is a heated rotating roller is measured for tension at a tension measuring place 2 between the next roller and this value is 0.2 cN / dtex or less. It is preferable.

FIG. 2 is a process diagram showing another example of the method for producing an aliphatic polyester fiber of the present invention. In FIG. 3, the traveling yarn is taken up by the preheating roller 4 and drawn with the heat setting means 1 which is a heated rotating roller. Heat setting means 1 which is a heated rotating roller
The traveling yarn separated from the winder is measured for tension at 2 where the tension is measured with the winder, and this value is preferably 0.2 cN / dtex or less.

  Even when these production methods are adopted, the aliphatic polyester is a polylactic acid substantially having L-lactic acid and / or D-lactic acid as a main repeating unit, and the L-lactic acid or D-lactic acid of the polylactic acid. It can be preferably adopted that the ratio is 95 mol% or more.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, each characteristic value in an Example was calculated | required with the following method.

A. A sample with a shrinkage stress of 20 cm is looped to 10 cm, and the temperature is increased from room temperature to 200 ° C. using a thermal stress measuring machine TYPEPE-2S manufactured by Kanebo Engineering under conditions of an initial load of 0.03 cN / dtex and a heating rate of 150 ° C./min. A warm heat shrink stress curve is obtained. The maximum shrinkage stress (cN / dtex) at this time was read and used as the fiber shrinkage stress (cN / dtex).

B. Strength Using a tensile tester (Tensilon UCT-100 type) manufactured by Orientec Co., Ltd., a tensile test was conducted under the conditions of a sample length of 20 cm and a tensile speed of 20 cm / min. did.

C. Boiling water shrinkage under no load (S ₀ )
The sample is scraped 10 times, and the original length L0 is measured under a load of 0.1 cN / dtex. After removing the load to make it unloaded, the sample soot is removed for 15 minutes in a boiling water bath adjusted to 100 ° C. After this is air-dried, the post-treatment length L1 is measured under a load of 0.1 cN / dtex. The value obtained by the following equation was used as the boiling water shrinkage under no load.
S ₀ (%) = {(L 0 −L 1) / L 0} × 100

D. Boiling water shrinkage under load of 0.01 cN / dtex (S ₁ )
The sample is scraped 10 times, and the original length L0 is measured under a load of 0.1 cN / dtex. After removing the load, the load is attached so as to be 0.01 cN / dtex, and the soot of the sample is removed for 15 minutes in a boiling water bath adjusted to 100 ° C. After removing the load and air-drying it, the post-treatment length L1 is measured under a load of 0.1 cN / dtex. The value obtained by the following equation was used as the boiling water shrinkage under no load.
S ₁ (%) = {(L 0 −L 1) / L 0} × 100

E. A plain woven fabric (taffeta) having a warp yarn density of 100 yarns / cm and a weft yarn density of 100 yarns / cm is produced using fibers for measuring the shrinkage of the fabric. A 10 cm line is drawn in the weft direction of the woven fabric, and both ends are marked with a marker, followed by hot water treatment at 100 ° C. × 1 hr. After air drying, the distance L1 (cm) between the markers was measured, and the value obtained by the following equation was used as the shrinkage of the fabric.
Fabric shrinkage rate (%) = {(10−L 1) / 10} × 100

F. The tension of the running yarn (cN) is measured using a three-point tension meter, and the value obtained by dividing the value by the fineness (dtex) of the fiber at the measurement location is the tension of the running yarn (cN / dtex). It was.

Example 1
A poly-L-lactic acid chip having a melting point of 168 ° C., a weight average molecular weight of 120,000 and an L-form ratio of 98 mol% was dried for 12 hours in a vacuum dryer set at 105 ° C. The dried chip was melted by a pressure melter type spinning machine at a melter temperature of 220 ° C., introduced into a melt spinning pack having a spinning temperature of 220 ° C., and spun from a die hole of 0.23 mmφ−0.30 mmL. The spun yarn was cooled by a chimney wind at 20 ° C. and 30 m / min, and after converging by applying an oil agent, the spun yarn was taken up at 3000 m / min to obtain an undrawn yarn. The type of undrawn yarn obtained was 122 dtex-36f.

  This undrawn yarn was preheated and drawn at a first roller temperature of 90 ° C. using a hot roller-hot roller type drawing machine, and heat set at a 2nd roller temperature of 120 ° C. The 3rd roller temperature was room temperature. The stretching speed was 800 m / min, each roller was rotated 6 times, and the magnification between the 1st roller and the 2nd roller was 1.44 times, and the space between the 2nd roller and the 3rd roller was 1.005 times. The tension between the 2nd roller and the 3rd roller, which are heat setting rollers, was 0.02 cN / dtex.

  The physical properties of the fibers are as shown in Table 1. The mechanical properties were excellent and no problem in handling occurred. The shrinkage of the fabric made using this fiber was a very small value of 2.2%.

Example 2
A fiber was obtained in the same manner as in Example 1 except that the temperature of the 2nd roller was 130 ° C. The shrinkage rate of the fabric made using this fiber was a very small value of 1.3%.

Example 4
The fiber spun in the same manner as in Example 1 was cooled by a chimney wind at 20 ° C. and 30 m / min, and after converging by applying an oil agent, the first hot roller rotating at 1500 m / min and 4500 m / min. The film was stretched 3 times between the rotating second hot rollers. The first hot roller was 90 ° C and the second hot roller was 140 ° C. Winding was performed such that the tension of the running yarn coming out of the second hot roller was 0.15 cN / dtex.

  The physical properties of the fibers are as shown in Table 1. The mechanical properties were excellent and no problem in handling occurred. The shrinkage of the fabric made using this fiber was a small value of 3.5%.

Comparative Example 1
Polyethylene terephthalate containing 0.05 wt% of titanium dioxide as inorganic particles and having a melting point of 262 ° C. was dried with a vacuum dryer set at 150 ° C. for 5 hours. The dried chip was melted at a melter temperature of 285 ° C. with a pressure melter type spinning machine, introduced into a melt pack having a spinning temperature of 290 ° C., and spun from a 0.23D-0.30 L die hole. The spun yarn was cooled by a chimney wind of 30 m / min, applied with an oil agent and converged, and then taken up at 3000 m / min to obtain an undrawn yarn. The type of the undrawn yarn obtained was 156 dtex-36f.

  This undrawn yarn was preheated and drawn at a first roller temperature of 90 ° C. using a hot roller-hot roller type drawing machine, and heat set at a 2nd roller temperature of 130 ° C. The 3rd roller temperature was room temperature. The stretching speed was 800 m / min, each roller was rotated 6 times, and the magnification was 1.80 times between the 1st roller and the 2nd roller, and 1.005 times between the 2nd roller and the 3rd roller. The tension between the 2nd roller and the 3rd roller, which are heat setting rollers, was 0.31 cN / dtex.

The fiber physical properties are as shown in Table 1. The strength was as high as 5.0 cN / dtex, but the shrinkage stress was as high as 0.44 cN / dtex, so S ₀ and S ₁ were the same value. Therefore, the shrinkage rate of the fabric was as high as 7.3%.

Comparative Example 2
The same procedure as in Example 1 was used except that D-copolymerized polylactic acid having a melting point of 150 ° C., a weight average molecular weight of 150,000, and an L / D ratio of 94.8 / 5.2 was used instead of poly-L-lactic acid. A drawn yarn was obtained.

As shown in Table 1, the shrinkage stress was a low value of 0.12 cN / dtex, but S ₀ was a very high value of 46.9%, so S ₁ was also a high value of 25.0. . Therefore, the shrinkage rate of the fabric produced using this fiber was 21.1%, and it was extremely coarse due to significant shrinkage.

Comparative Example 3
In the same manner as in Example 1, an undrawn yarn of poly L lactic acid was obtained. This undrawn yarn was preheated and drawn at a first roller temperature of 70 ° C. using a hot roller-hot roller type drawing machine, and heat set at a 2nd roller temperature of 90 ° C. The 3rd roller temperature was room temperature. The stretching speed was 800 m / min, each roller was rotated 6 times, the magnification between the 1st roller and the 2nd roller was 1.4 times, and the space between the 2nd roller and the 3rd roller was 1.05 times. The tension between the 2nd roller and the 3rd roller, which are heat setting rollers, was 0.24 cN / dtex.

The physical properties of the fibers are as shown in Table 1. The mechanical properties were excellent and no problem in handling occurred. However, S ₀ of this fiber was as high as 15.4%, and S ₁ was also as high as 12.9%. Therefore, the shrinkage rate of the fabric produced using this fiber is as high as 10.7%, and the shape stability of the fabric is inferior.

It is process schematic which shows an example of the manufacturing method of the aliphatic polyester fiber of this invention. It is process schematic which shows another example of the manufacturing method of the aliphatic polyester fiber of this invention.

Explanation of symbols

1: Heat setting means 2: Tension measuring means 3: Feed roller 4: Preheating roller 5: Stretching zone

Claims (1)

In the method for producing polylactic acid fiber in which 95% by mole or more is made of L-lactic acid , heating and stretching is performed between the preheating roller (A) and the heated rotating roller (B). This is the only heat setting means in the process from spinning the fiber, going through the drawing process, and winding up, and when rotating the heated yarn by bringing the running yarn into contact with the heated rotating roller (B) A method for producing a polylactic acid fiber, characterized in that the temperature of the roller (B) is 100 to 150 ° C., and the tension of the traveling yarn separated from the rotating roller (B) is 0.2 cN / dtex or less.

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