JP2008163511A - Crimped polylactic acid yarn and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crimped polylactic acid yarn having all of excellent highly bulky property, high bulkiness-recovering property and heat resistance, also rich in touch feeling and elasticity, excellent in washing durability, and further having a good antistatic property and discoloration-preventing property. <P>SOLUTION: This crimped polylactic acid yarn of which fiber cross section is an eccentric hollow cross section, consisting of the polylactic acid is provided by satisfying all of the following requirements. Provided that, (1) Hollowness rate is 20 to 50%, (2) Crimping rate is 10 to 40%, and (3) eccentricity rate is 10 to 40%. Further the fiber surface is covered with a silicone-based polymer membrane, and the silicone-based polymer membrane contains an amino-modified silicone having an alkoxy terminal or amino-modified silicone having a hydroxy terminal and an aminoalkoxysilane as essential components. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a polylactic acid candy having both excellent bulkiness, bulkiness recovery and heat resistance, excellent texture and elasticity, excellent washing durability, and excellent antistatic and discoloration prevention properties. It relates to shrinking yarn.

  Aromatic polyester fibers such as polyethylene terephthalate are widely used because of their excellent mechanical properties, various fastnesses, and wash and wear properties. In recent years, it has been used in large quantities for clothing, as well as for industrial materials, sanitary materials, or for cotton inserts such as futons and cushions. However, in the use of filling cotton, filling cotton made of polyester fiber made of polyethylene terephthalate fiber is difficult to be decomposed by natural microorganisms and is partially recycled after use, but most of them require treatment such as incineration. Therefore, there is a drawback that the disposal is limited.

  In order to solve these problems, fibers using biodegradable polymers have been proposed.

For example, a side-by-side type composite fiber composed of two types of polyesters with different heat shrinkage properties, one of which is polylactic acid, has been proposed. However, when left in nature, components other than polylactic acid do not decompose and are discarded. The problem of restriction remains (Patent Document 1). In addition, a spontaneously crimped composite fiber in which different biodegradable aliphatic polyesters are eccentrically bonded has also been proposed, which eliminates the problem of disposal, but uses a resin with low crystallinity. There was a problem and the texture was not enough. In addition, since polyethylene glycol or the like is copolymerized with polylactic acid, the polymerization cost is high, and there is a problem in terms of quality and operation (Patent Document 2). Furthermore, composite fibers in which polylactic acids having different molecular weights are joined side-by-side have been proposed. However, since low molecular weight polylactic acid is used as one component, problems still remain in heat resistance and texture (Patent Document 3). Furthermore, although hollow polylactic acid fiber is known, it is necessary to give crimp separately (patent document 4).
JP 2000-54228 A JP 09-209216 A JP 2003-301332 A JP 2004-238754 A

  The object of the present invention is to solve the above-mentioned problems, and has both excellent bulkiness, bulkiness recovery and heat resistance, which cannot be achieved by the prior art, and also has a high texture and elasticity, and is excellent in washing durability. The present invention relates to a polylactic acid crimped yarn having excellent antistatic properties and discoloration prevention properties.

The inventors of the present invention have reached the present invention as a result of intensive studies to solve the above problems. That is, the present invention is as follows.
1. A polylactic acid crimped yarn comprising polylactic acid, the fiber cross section of which is an eccentric hollow cross section, and satisfies all of the following requirements.
(1) Hollow ratio is 20 to 50%
(2) Crimp rate of 10-40%
(3) Eccentricity is 10-40%
Polylactic acid crimped yarn listed.
2. 1. The fiber surface is coated with a silicone polymer film, and the silicone polymer film contains the following [A] and [B] as essential components. The polylactic acid crimped yarn described.
[A]: alkoxy-terminated amino-modified silicone or hydroxy-terminated amino-modified silicone [B]: aminoalkoxysilane 1. The silicone-based polymer film further contains at least one of the following [C] to [E] as a subcomponent. Or 2. The polylactic acid crimped yarn described.
[C]: Cationic surfactant [D]: Anionic surfactant [E]: Nonionic surfactant 2. The silicone-based polymer film contains the [A] to [E] components in the following ratio (weight ratio). The polylactic acid crimped yarn described.
([A] + [B]) / ([C] + [D] + [E]) = 50/50 to 90/10
5. 1. A polylactic acid melt polymer is spun from a die surface, and the spun yarn is cooled by cooling air flowing only from one direction. The manufacturing method of the polylactic acid crimped yarn of description.

  According to the present invention, a polylactic acid basket having both excellent bulkiness, bulkiness recovery and heat resistance, excellent texture and elasticity, excellent washing durability, and excellent antistatic and discoloration prevention properties. A crimped yarn can be provided.

  Hereinafter, the present invention will be described in detail.

  The polylactic acid referred to in the present invention refers to a polymer obtained by polymerizing oligomers of lactic acid such as lactic acid or lactide, and those having an optical purity of 90% or more of L-form or D-form are preferred. When the optical purity of the L-form or D-form is 90% or higher, the melting point becomes high. The optical purity of the L-form or D-form is more preferably 97% or more. In addition, components other than lactic acid may be copolymerized as long as the properties of polylactic acid are not impaired, polymers and particles other than polylactic acid, flame retardants, antistatic agents, matting agents, deodorants, antibacterial agents An additive such as an agent, an anti-acid agent or a color pigment may be contained. An end-capping agent such as a carbodiimide compound may be contained for the purpose of suppressing hydrolysis of polylactic acid and suppressing deterioration of physical properties of the product over time. From the balance between mechanical properties and moldability, the polylactic acid polymer molecular weight is preferably 50,000 to 500,000 in terms of weight average molecular weight. More preferably, it is 100,000 to 300,000.

  The method for producing polylactic acid used in the present invention is not particularly limited. Specifically, there is a manufacturing method disclosed in JP-A-6-65360. That is, a direct dehydration condensation method in which lactic acid is dehydrated and polymerized as it is in the presence of an organic solvent and a catalyst. Further, there is a method in which at least two types of homopolymers disclosed in JP-A-7-173266 are copolymerized and transesterified in the presence of a polymerization catalyst. Furthermore, there is a method disclosed in US Pat. No. 2,703,316. That is, an indirect polymerization method in which lactic acid is once dehydrated to form a cyclic dimer and then subjected to ring-opening polymerization.

  The polylactic acid used in the present invention preferably has a melting point of 130 ° C. or higher. When the melting point is lower than 130 ° C., there is a risk that the quality of the product may be impaired, for example, the fusion between single yarns becomes significant during spinning, particularly spinning, and further, such as drawing failure. The melting point is preferably 150 ° C. or higher, more preferably 160 ° C. or higher.

The polylactic acid crimped yarn of the present invention has an eccentric hollow cross section. By setting it as an eccentric hollow cross section, spiral crimp can be provided and the bulkiness is improved. The hollow ratio of the eccentric hollowed polylactic acid crimped yarn of the present invention is 20 to 50%, and the eccentricity is 10 to 40%.

In addition, the hollow ratio said here represents the area ratio of the hollow part with respect to the area calculated | required from the external shape of the fiber cross section in percentage. The eccentricity is a percentage of the difference between the center of gravity of the polylactic acid fiber and the center of gravity of the hollow portion in the fiber cross section.

  The hollow ratio is preferably higher from the viewpoint of reducing the apparent density and improving the spiral crimp expression, but if it is too high, the hollow portion is crushed or cracked. A preferable hollow ratio is 20% to 35%.

  The eccentricity is preferably higher from the viewpoint of improving the spiral crimp expression, but if it is too high, the discharged yarn bends during spinning, and if this progresses excessively, the spun yarn adheres to the spinneret and is cut. And stable spinning cannot be performed. Moreover, the crack of a hollow part generate | occur | produces. A preferable eccentricity is 20 to 30%.

  The crimp rate is 10 to 40%, preferably 15 to 30%. When the crimping rate is less than 10%, the bulkiness is not sufficiently generated. On the other hand, when the crimping rate exceeds 40%, the entanglement becomes too high, resulting in entanglement and poor card passage.

  The number of crimps is not particularly limited, but is preferably 3/25 mm to 20/25 mm from the viewpoint of balance of bulkiness characteristics. If the number of crimps is too low, a good texture with a light feeling will not be achieved, and if it exceeds 20 peaks / 25 mm, the bulkiness may be reduced.

  The polylactic acid crimped yarn in the present invention is preferably coated with a silicone polymer film on the fiber surface in order to obtain excellent bulky resilience. When the fiber surface is covered with the silicone polymer film, the slipperiness is excellent and the short fibers are very easy to unravel. This makes it possible to produce a high-quality fiber product in which the short fibers are uniformly dispersed and the cotton has very little coarseness.

The polylactic acid crimped yarn of the present invention is covered with a silicone polymer film, and the silicone polymer film in the present invention contains the following [A] and [B] as essential components. Is preferred.
[A]: alkoxy-terminated amino-modified silicone or hydroxy-terminated amino-modified silicone [B]: aminoalkoxysilane.

  As the alkoxy-terminated amino-modified silicone or hydroxy-terminated amino-modified silicone used in the present invention, those represented by the following general formula (1) are preferable, and the amino equivalent is 1000 to 10,000, and the viscosity at 25 ° C. is 100 to 10,000 Pa · s. More preferably.

Wherein R1 to R5 are alkyl groups having 1 to 5 carbon atoms, R6 to R7 are hydrogen or alkyl groups having 1 to 5 carbon atoms, and A1 is an alkyl group having 1 to 5 carbon atoms having 1 to 5 amino groups. Group, m and n each represents a positive integer.)

  Preferable specific examples include methoxy-terminal amino-modified silicone.

  As an amino alkoxysilane used by this invention, what is shown to following General formula (2) is preferable.

(In the formula, R8 to R10 each represent an alkyl group having 1 to 5 carbon atoms, and A2 represents an alkyl group having 1 to 5 carbon atoms having 1 to 5 amino groups.)

  Preferable specific examples include methyldimethoxydiaminosilane.

The silicone-based polymer film in the present invention preferably contains at least one of the following [C] to [E] as subcomponents in addition to the above preferable essential components.
[C]: Cationic surfactant [D]: Anionic surfactant [E]: Nonionic surfactant

  The cationic surfactant in the present invention is a flexible electrostatic agent, preferably a quaternary ammonium sulfate salt or a quaternary ammonium phosphate salt, and more preferably a quaternary ammonium phosphate salt represented by the general formula (3).

(In the formula, R11 represents an alkyl group having 6 to 22 carbon atoms, and R12 to R15 each represents hydrogen or an alkyl group having 1 to 5 carbon atoms.)

  Preferable specific examples include trimethyl lauryl ammonium dimethyl phosphate.

  The anionic surfactant in the present invention is an antistatic smoothing agent or a reaction catalyst between essential components, preferably a metal soap having 8 to 22 carbon atoms, and more preferably a metal soap having 12 to 18 carbon atoms. The metal of the metal soap is preferably an alkali metal. Preferable specific examples include potassium laurate.

  The nonionic surfactant in the present invention is not particularly limited as long as the main component can be emulsified, and examples thereof include polyoxyalkylene aliphatic ether and polyoxyalkylene aromatic ether. Preferable specific examples include polyoxyethylene tridecyl alcohol.

It is important that the silicone-based polymer film covering the fiber surface of the polylactic acid crimped yarn of the present invention contains the components [A] to [E] in the following ratio (weight ratio).
([A] + [B]) / ([C] + [D] + [E]) = 50/50 to 90/10

  That is, the ratio between the essential component and the subcomponent must be within the range satisfying the above formula, and is preferably 60/40 to 80/20. If [A] + [B] is less than 50, the texture is poor, and if it exceeds 90, the antistatic property is deteriorated and problems such as poor process passage occur. In addition, the product becomes inferior, such as yellowing.

  The silicone polymer film of the present invention can be attached to a crimped yarn as a silicone oil to form a film. The amount of the oil agent attached to the polylactic acid crimped yarn is not particularly limited, but is generally preferably 0.01 to 10% by weight relative to the weight of the crimped yarn, and more preferably 0.1% in view of the initial bulkiness. ~ 1% by weight is good.

  The polylactic acid crimped yarn of the present invention can be produced, for example, as follows.

  Polylactic acid polymer is melted and spun using a normal spinning machine. At this time, in order to obtain a hollow eccentric cross section, for example, the shape of the discharge hole is a hollow base made of four slits, and the hollowness and eccentricity are changed and adjusted by adjusting the structure and arrangement of the slits. It is preferable that the polylactic acid melt polymer is spun from the die surface, and the spun yarn is cooled by cooling air flowing only from one direction. In particular, cooling immediately after spinning is performed by strongly blowing 20 ° C. cooling air, and after winding, a slight mechanical crimp is imparted after liquid bath stretching. Next, after the oil agent is applied, the fiber of the present invention can be obtained by high-temperature heat treatment in a relaxed state to develop a spiral-shaped crimp.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these specific examples.

(1) Fineness:
The fineness (dtex) was measured by the method shown in JIS L-1015.

(2) Number of crimps:
The number of crimps (mountain / 25 mm) was measured by the method shown in JIS L-1015.

(3) Thermal yellowing degree:
Each fiber sample after 1 g of sample cotton was allowed to stand at 170 ° C. for 24 hours was opened and each fiber sample was aligned so that the fibers were parallel to each other. The b value was measured using “SM-3”. The Δb value obtained by subtracting the b value before standing from the b value after standing was defined as the degree of thermal yellowing, and 1 or less was marked as ◎.

(4) Withstand voltage:
The sample cotton is allowed to stand for 12 hours under the conditions of a temperature of 30 ° C. and a relative humidity of 40%, and then the sample cotton is introduced so that the sliver basis weight is 4.3 g / m. Using a TOYODA CK-7D manufactured by Toyota Industries Corporation as a card machine, in the card process, 10 cm on the web with a width of 30 cm running at a temperature and humidity of 50 m / min. [V] was measured. This measurement was repeated 5 times, and the average value of the values was desired to be −500 to 500 [V].

(5) Durability of texture Side cotton 25 cm × 25 cm (No. 40 / No. 40: T120 pieces / L120 pieces (inch)) is stuffed with open sample cotton having a basis weight of 0.04 g / cm ² and JIS 1096 After washing 10 times by the method shown in Method A of 6.2.1990, the texture was judged in three stages based on tactile sensation.

(6) Hollow ratio An area (A) and a hollow cross section obtained from an outer shape including a hollow portion of a thread (hollow cross section short fiber) 1 as shown in FIG. The area (B) of the hollow portion 2 was calculated from the following formula, the number of measurements was 20 times, and the average value of the values was defined as the hollow ratio.
Hollow ratio (%) = (B / A) × 100.

(7) Eccentricity Taken a cross-sectional photograph of the yarn with an optical microscope manufactured by Nippon Optical Co., Ltd., as shown in FIG. 1, the center of gravity (C) of the yarn (hollow cross-section short fiber) 1, the center of gravity (D) of the hollow portion and The fiber radius was obtained and calculated from the following formula. The number of measurements was set to 20 times, and the average of the values was defined as the eccentricity.
Eccentricity (%) = distance between (C−D) / fiber radius × 100.

(8) Biodegradability A sample of 10 g of the obtained fiber was buried in the soil and taken out after 6 months. When the strength of this fiber is less than 50% of the initial strength before burying, the biodegradability is good (○), and the strength exceeds 50% of the strength before burying. Was evaluated as having poor biodegradability (×). Tensile strength (cN) was determined in accordance with the method described in JIS L-1015.

(9) Heat resistance evaluation (melting point)
A differential scanning calorimeter DSC-7 manufactured by Perkin Elma was used, and the rate of temperature increase was measured under the condition of 10 ° C./min. The temperature at which a peak was obtained in the obtained endothermic curve was taken as the melting point.

Example 1
A polylactic acid chip (Nature Works, grade 6201D) having a melting point of 170 ° C. was dried with a hot air dryer set at 100 ° C. for 10 hours. The dried chip was melt-spun with a pressure melter type spinning machine at a melter temperature of 240 ° C. and introduced into the melt pack at a spinning temperature of 240 ° C., and the slit width was 0.13 mm, the slit diameter was 1.2 mm, the hole length was 0. Spinning was performed from an eccentric hollow spinneret having 180 holes with 30 mm pores. The spun yarn was asymmetrically cooled by a chimney wind at 20 ° C. and 160 m / min. After cooling, the oil agent was applied and converged, and then taken out at 1200 m / min to obtain an undrawn yarn. The obtained undrawn yarn was employed and was drawn up to 700,000 dtex, 3.0 times in a 90 ° C. liquid bath, then mechanically crimped with a stuffer box, cut to 76 mm, and a hollow ratio of 30% A short polylactic acid fiber having an eccentricity of 20% was obtained (SF-1). Oil was given to the fiber so that the oil agent shown in Table 2- (1) was 0.5% by weight with respect to the fiber by a spray method, and heat treatment was performed at 145 ° C. for 10 minutes. Table 1 shows the evaluation results for the obtained cotton. There was no discoloration due to polylactic acid, no yellowing due to heat treatment, and excellent bulkiness due to structural difference crimp.

Example 2
A polylactic acid chip (Nature Works, grade 6201D) having a melting point of 170 ° C. was dried with a hot air dryer set at 100 ° C. for 10 hours. The dried chip was melt-spun with a pressure melter type spinning machine at a melter temperature of 240 ° C. and introduced into the melt pack at a spinning temperature of 240 ° C., and the slit width was 0.13 mm, the slit diameter was 1.2 mm, the hole length was 0. Spinning was performed from an eccentric hollow spinneret having 180 holes with 30 mm pores. The spun yarn was asymmetrically cooled by a chimney wind at 20 ° C. and 100 m / min. After cooling, the oil agent was applied and converged, and then taken out at 1200 m / min to obtain an undrawn yarn. The obtained undrawn yarn was employed and was drawn up to 700,000 dtex, 3.0 times in a 90 ° C. liquid bath, then mechanically crimped with a stuffer box, cut to 76 mm, and a hollow ratio of 30% A short polylactic acid fiber having an eccentricity of 20% was obtained (SF-2). The oil agent shown in Table 2-1 was applied to the fiber by spraying so as to be 0.5% by weight with respect to the fiber, followed by heat treatment at 145 ° C. for 10 minutes. Table 1 shows the evaluation results for the obtained cotton. There was no discoloration due to polylactic acid, no yellowing due to heat treatment, and excellent bulkiness due to structural difference crimp.

Comparative Example 1
Polylactic acid chips having a melting point of 170 ° C. (Nature Works; grade 6201D) and polylactic acid chips having a melting point of 150 ° C. (Nature Works; grade 6751D) were each dried for 10 hours with a hot air drier set at 100 ° C. In a compound spinning machine, melt spinning at a melter temperature of 240 ° C., introducing the melt into a melt pack at a spinning temperature of 240 ° C., and 180 pores having a slit width of 0.13 mm, a slit diameter of 1.2 mm, and a pore length of 0.30 mm are provided. A side-by-side type composite yarn was obtained by spinning from a spinneret having holes. Then, after giving and converging the oil, it was taken up at 1200 m / min to obtain an undrawn yarn. The obtained undrawn yarn is employed and is drawn to 700,000 dtex, and is drawn 3.0 times in a 90 ° C liquid bath, then mechanically crimped with a stuffer box, cut to 76 mm, and polylactic acid short fiber Got. The oil agent shown in Table 2-1 was applied to the fiber by spraying so as to be 0.5% by weight with respect to the fiber, followed by heat treatment at 145 ° C. for 10 minutes. Table 1 shows the evaluation results for the obtained cotton. Although the obtained raw cotton was excellent in bulkiness and texture, it was inferior in yellowing and heat resistance due to heat treatment since a low melting point polymer was used.

Comparative Example 2
(SF2) obtained in Example 2 was supplied with oil of 2 shown in Table 2 by spraying so as to be 0.5% by weight with respect to the fiber, and was subjected to heat treatment at 145 ° C. for 10 minutes. . As shown in Table 1, the obtained fibers had poor antistatic properties and were discolored by heat treatment. Moreover, the feeling of squeaking after washing became strong and the slipperiness was poor.

Comparative Example 3
A polylactic acid chip (Nature Works, grade 6201D) having a melting point of 170 ° C. was dried with a hot air dryer set at 100 ° C. for 10 hours. The dried chip was melt-spun with a pressure melter type spinning machine at a melter temperature of 240 ° C. and introduced into the melt pack at a spinning temperature of 240 ° C., and the slit width was 0.13 mm, the slit diameter was 1.2 mm, the hole length was 0. Spinning was performed from a hollow spinneret having 180 holes with 30 mm pores. The spun yarn was asymmetrically cooled by a chimney wind at 20 ° C. and 100 m / min. After cooling, the oil agent was applied and converged, and then taken out at 1200 m / min to obtain an undrawn yarn. The obtained undrawn yarn is employed and is drawn to 700,000 dtex, and is drawn 3.0 times in a 90 ° C liquid bath, then mechanically crimped with a stuffer box, cut to 76 mm, and polylactic acid short fiber Got. The oil agent shown in Table 2-2 was applied to the fiber by spraying so that the amount of oil was 0.5% by weight with respect to the fiber, and heat treatment was performed at 145 ° C. for 10 minutes. Table 1 shows the evaluation results for the obtained cotton. The obtained fiber was poor in antistatic property and discolored by heat treatment. Further, the feeling of squeezing after washing was strong and the slipperiness was poor, and crimping due to structural difference crimping did not occur, and sufficient bulkiness could not be obtained.

It is the schematic explaining the method of calculating | requiring a hollow rate and an eccentric rate.

Explanation of symbols

1: Cross section of eccentric hollow fiber (cross section: A)
2: Eccentric hollow part (hollow part area: B)
3: Fiber center of gravity position: C
4: Center of gravity of hollow part: D

Claims (5)

A polylactic acid crimped yarn comprising polylactic acid, the fiber cross section of which is an eccentric hollow cross section, and satisfies all of the following requirements.
(1) Hollow ratio is 20 to 50%
(2) Crimp rate of 10-40%
(3) Eccentricity is 10-40% The polylactic acid crimped yarn according to claim 1, wherein the fiber surface is coated with a silicone polymer film, and the silicone polymer film contains the following [A] and [B] as essential components.
[A]: alkoxy-terminated amino-modified silicone or hydroxy-terminated amino-modified silicone [B]: aminoalkoxysilane The polylactic acid crimped yarn according to claim 1 or 2, wherein the silicone-based polymer film further contains at least one of the following [C] to [E] as a subcomponent.
[C]: Cationic surfactant [D]: Anionic surfactant [E]: Nonionic surfactant The polylactic acid crimped yarn according to claim 3, wherein the silicone-based polymer film contains the components [A] to [E] in the following ratio (weight ratio).
([A] + [B]) / ([C] + [D] + [E]) = 50/50 to 90/10   2. The method for producing a polylactic acid crimped yarn according to claim 1, wherein the polylactic acid melt polymer is spun from the die surface, and the spun yarn is cooled by cooling air flowing only from one direction.

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