JP2008025059A - Polylactic acid fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid fiber that has excellent abrasion resistance, persistently maintaining the excellent effect for improving the wear resistance property, shows good process passing property in the steps of not only spinning and drawing, but also a variety of processing steps and weaving and knitting steps, thus the fiber can be obtained with good operability. <P>SOLUTION: This fiber includes at least one polylactic acid including silicon powder as one component wherein the content of the silicon power is 0.1 to 10 mass% par the fiber mass. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polylactic acid fiber having at least one component of polylactic acid containing silicone powder and having excellent wear resistance and high elongation properties.

  In recent years, polylactic acid fibers have been developed for various uses such as general clothing use, interior use such as curtains and carpets, and vehicle interior use. Among them, the development of industrial materials such as agricultural materials and civil engineering materials that require biodegradability is most expected.

  However, polylactic acid fiber has the disadvantage of poor wear resistance due to its high surface friction coefficient. Among industrial materials, it requires wear resistance, bending wear resistance, scratch resistance, and slidability. And development into the field was not progressing. For example, in netting processing such as safety nets used at construction sites and net-like bag materials such as bottom filters that are used by filling stones etc. in landfill revetments for rivers, harbors, etc. Since the knitting structure is complicated, the load and friction applied to the knitted fabric in the net making process are applied not only in a straight line but also in multiple directions. For this reason, there existed a fault that fluffing, a thread breakage, whitening, etc. arise in a processing process. In order to solve this problem, it is necessary to reduce the processing speed, and there is a problem that the operability is deteriorated.

  Further, when these textile products are used, they are subjected to friction and impact caused by the flow of stones packed inside the product, and are subjected to friction and impact caused by drift stones and driftwood outside the product. For this reason, there was a problem in durability, such as fluffing caused by loads from multiple directions repeatedly applied to the inside and outside of the product, and the fibers being worn out.

  Furthermore, the impact of the high surface friction coefficient of polylactic acid fibers is not limited to the problems of durability and processing during the production of the above-mentioned textile products, but also causes problems when manufacturing fibers. ing.

  For example, during melt spinning, since the yarn usually travels at a high speed of 1000 to 7000 m / min, fluff and yarn breakage are likely to occur due to increased friction between the yarn and the guides. Further, in the drawing process, the yarn is easily wound around the guides and the rollers and the yarn breakage is likely to occur. Further, in the crimping process, in particular, the false twisting process, the frictional force between the yarn and the twister becomes excessive, so that yarn breakage frequently occurs and the processing may be difficult. In addition, when weaving and knitting, not only the friction between the yarn and the metal, but also the friction between the yarn and the yarn, there is a problem that the generation of fuzz is remarkable and the process passability and the quality of the fabric are greatly reduced. there were.

  Patent Document 1 describes polylactic acid containing 0.1 to 5.0% by mass of fatty acid bisamide and / or alkyl-substituted fatty acid monoamide as a polylactic acid fiber with improved wear resistance and processability. Has been. And the manufacturing method which provides the spinning oil agent which contains at least 1 type of smoothing agent chosen from fatty acid ester, polyhydric alcohol ester, ether ester, silicone, and mineral oil to the melt-spun fiber is described.

  However, even in this polylactic acid fiber, the frictional resistance cannot be sufficiently reduced, and a large amount of fluff is generated at the time of drawing, and it is not possible to suppress the process passability in spinning and processing steps and the deterioration of product quality. It was.

  Patent Document 2 contains 0.1 to 30% by weight of a specific function-imparting agent as a biodegradable polyester fiber excellent in process stability from yarn production to weaving and weaving processes, and includes a total of lubricant and surfactant. The polyester fiber which added 70 mass% or more and the oil agent which exists in the range of 0.04-0.35 in an oiliness index is described. Patent Document 3 discloses that 50 to 98% by weight of polyorganosiloxane and / or mineral oil, 1 to 10% by weight of polyether-modified polyorganosiloxane and / or amino-modified polyorganosiloxane, and 8 to 8 carbon atoms on the fiber surface. Biodegradable polyester with a reduced coefficient of friction by applying an oil containing 1 to 10% by weight of a partial phosphate ester salt of a compound obtained by adding 0 to 10 moles of ethylene oxide and / or propylene oxide to 18 alcohols Fibers are described.

  However, since all of these fibers are provided with a specific oil agent on the fiber surface in order to improve the wear resistance, there is a problem that the effect of the wear resistance is reduced by dropping off the oil agent. Further, when heat treatment is performed at a high temperature during stretching or the like, smoke may be generated on the roller or the like, which causes a problem that the working environment is remarkably lowered.

Moreover, what added the metal particle in polyester is described as what improves the abrasion resistance of a polyester monofilament (patent document 4). However, such a monofilament has a problem that although the wear resistance is improved to some extent, a contact portion such as a roller surface is worn during spinning, drawing and processing. In addition, a thin single filament fineness such as a multifilament has been difficult to manufacture due to problems such as nozzle pack pressurization and metal particle dispersion.
JP 2004-091968 JP2003-138485 JP2005-200793 JP 3-76813

  The present invention solves the above-mentioned problems, is a polylactic acid fiber excellent in wear resistance, is excellent in the durability of the effect of improving wear resistance, and not only spinning and drawing processes, but also various processing processes In addition, it is a technical problem to provide a polylactic acid fiber that is excellent in process passability and can be obtained with good operability in the knitting and weaving process.

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

  That is, the present invention provides a polylactic acid fiber comprising polylactic acid containing silicone powder as at least one component, and containing 0.1 to 10% by mass of silicone powder based on the fiber mass. It is a summary.

Hereinafter, the present invention will be described in detail.
The polylactic acid fiber of the present invention is a fiber having at least one component of polylactic acid containing silicone powder, and even if it is a single component type consisting only of polylactic acid containing silicone powder, It may be a composite type fiber (composite fiber) composed of the polylactic acid contained and other components.

  Examples of polylactic acid containing silicone powder include poly-D-lactic acid, poly-L-lactic acid, a copolymer of D-lactic acid and L-lactic acid, and a copolymer of D-lactic acid and hydroxycarboxylic acid. And a polymer selected from the group consisting of a copolymer of L-lactic acid and hydroxycarboxylic acid, a copolymer of D-lactic acid, L-lactic acid and hydroxycarboxylic acid, or a blend thereof, L- A mixture of lactic acid and D-lactic acid (stereo complex) can be mentioned.

  Examples of the hydroxycarboxylic acid in the case of copolymerizing hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxyoctanoic acid and the like. Among these, hydroxycaproic acid or glycolic acid is particularly preferable from the viewpoint of microbial degradation performance and low cost.

  In any of the polymers, the polylactic acid preferably has an L-lactic acid content ratio (copolymerization ratio or mixing ratio) in the polylactic acid of 85.0 to 99.5 mol%. Since the ratio of L-lactic acid is a factor affecting the heat resistance, when the content ratio of L-lactic acid is lower than this range, the melting point is low, the fiber is inferior in heat resistance, the yarn-making property is deteriorated, and the heat stretching is performed. It becomes difficult to do. On the other hand, when the content ratio of L-lactic acid is higher than this range, the crystallization temperature becomes high, so that the decomposition rate becomes low and the fiber is inferior in biodegradability.

  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 once generate lactide which is a cyclic dimer, followed by ring-opening polymerization, and L-lactic acid and 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, but the polylactic acid used in the present invention is a polylactic acid obtained by any method. Also good.

  In order to improve various properties such as strength, the number average molecular weight of polylactic acid is preferably as high as possible, preferably 50,000 or more, more preferably 100,000 or more, and even more preferably 200,000 or more. A number average molecular weight of less than 50,000 is not preferable because the strength and elongation characteristics of the fiber are lowered. On the other hand, if the number average molecular weight exceeds 300,000, the biodegradation performance peculiar to polylactic acid is impaired, which is not preferable.

  The silicone powder contained in the polylactic acid is preferably spherical in shape, and particularly preferably spherical.

  And as a particle size of silicone powder, it is preferable that an average particle diameter is 5 micrometers or less, and it is preferable that it is 2 micrometers or less especially. When the average particle diameter exceeds 5 μm, problems such as clogging of the filter medium and a decrease in spinning operability due to thread breakage occur when spinning in the polylactic acid, and also cause thread breakage in the drawing process. Cheap.

The silicone powder has a general formula (RSiO _3/2 ) n [where R is a monovalent organic group, and n is an integer of 1000 or more. Or a spherical silicone rubber fine particle obtained by a hydrosilylation reaction between a vinyl group-containing polysiloxane and a methyl hydrogen polysiloxane, or a spherical silicone resin fine particle comprising a silsesquioxane having a three-dimensional network structure represented by Is preferred.

  Examples of the monovalent organic group R in the general formula include alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl groups, aryl groups such as phenyl and tolyl groups, vinyl groups, and allyl groups. Illustrative examples include alkenyl groups such as 3,3,3-trifluoropropyl group, γ-mercaptopropyl group, γ-glycidoxypropyl group, γ-methacryloxypropyl group, etc. In view of the above, it is preferable that 50 mol% or more of all R is a methyl group.

  And the polylactic acid fiber of this invention contains 0.1-10 mass% of silicone powder with respect to fiber mass, and it is preferable to make it contain 0.5-5.0 mass% especially. When the content of the silicone powder is less than 0.1% by mass, the effect of improving the wear resistance becomes insufficient. On the other hand, when the content exceeds 10% by mass, the fluidity of the polylactic acid decreases, and spinning, stretching, and winding are not possible. As the operability deteriorates, the mechanical properties such as strength and elongation are inferior.

  Silicone powder can be added to and mixed with polylactic acid at any stage from polymerization to spinning process. A master chip containing a high concentration of silicone powder in polylactic acid is produced in advance and then spun. Sometimes added to polylactic acid and mixed.

  In addition, when the polylactic acid fiber of the present invention is a composite fiber, the other component used together with the polylactic acid containing silicone powder is not particularly limited as long as it is a thermoplastic resin, but polylactic acid not containing silicone powder is used. Alternatively, polyester having a main component of polyethylene terephthalate, polyamide, or the like can be used.

  Polyesters based on polyethylene terephthalate include dicarboxylic acid components such as isophthalic acid, 5-sodium sulfoisophthalic acid, phthalic anhydride, adipic acid and sebacic acid as copolymerization components, and 1,6-hexadiol and cyclohexane. A diol component such as dimethanol may be contained.

  The polylactic acid fiber of the present invention may be a multifilament composed of a plurality of single yarns or a monofilament composed of a single yarn. The cross-sectional shape of the single yarn may be a round shape, a polygonal shape or a multi-leaf shape, or may have a hollow portion. Moreover, examples of the cross-sectional shape when the polylactic acid fiber (single yarn) of the present invention is a composite fiber include a core-sheath type, a bonded type, a parallel type, a split type, a multilayer type, a radial type, and a sea-island type. However, in any shape, it is preferable that the polylactic acid containing silicone powder is exposed to the fiber surface.

  Moreover, when setting it as composite fiber, it is preferable that the ratio of the polylactic acid containing silicone powder shall be 10 mass% or more in fiber mass. If it is less than 10% by mass, a sufficient effect of improving wear resistance cannot be obtained.

When the polylactic acid fiber of the present invention is a multifilament, the single yarn fineness is preferably 1 to 200 dtex, and the total fineness is preferably 36 to 5000 dtex, and particularly preferably 36 to 1500 dtex. In the case of a monofilament, the fineness is preferably 150 to 5000 dtex.
Furthermore, the polylactic acid fiber of the present invention may be used as a long fiber or a short fiber.

  In the polylactic acid fiber of the present invention, as long as the effect is not impaired, for example, a heat stabilizer, a crystal nucleating agent, a matting agent, a pigment, a light resistance agent, a weather resistance agent, an antioxidant, Antibacterial agents, fragrances, plasticizers, dyes, surfactants, surface modifiers, various inorganic and organic electrolytes, fine powders, flame retardants and other additives and fatty acid amides that increase knot strength, such as metaxylylene bisstearyl Amide, metaxylylene bis oleyl amide, xylene bis stearamide, ethylene bis stearyl amide, ethylene bis stearamide, and the like can be added.

  Next, the manufacturing method of the polylactic acid fiber (multifilament, long fiber) of this invention is demonstrated. A polylactic acid chip containing a high concentration of silicone powder is manufactured in advance, and this is mixed with the polylactic acid chip at the time of spinning, or the silicone powder and the polylactic acid chip are mixed at the time of spinning, and these are used for melt spinning. Do. In the case of a composite fiber, melt spinning is performed using other components using an ordinary composite spinning apparatus. After melt spinning, the yarn is cooled, an oil agent is applied, and after being wound up as an undrawn yarn or once without being wound up, it is continuously drawn. At this time, the draw ratio is set to 4 to 8 times, and heat drawing is performed at 130 to 145 ° C. using a heating roller between the rollers, and winding is performed.

  Since the polylactic acid fiber of the present invention uses at least a part of polylactic acid containing silicone powder, it has excellent wear resistance and excellent durability of the effect of improving wear resistance. Thus, it is possible to obtain good operability without occurrence of yarn breakage. Moreover, since the polylactic acid fiber of the present invention is excellent in process passability in various processing steps and knitting and weaving steps, it can be suitably used in various fields such as apparel use, industrial materials, and civil engineering use.

Next, the present invention will be described specifically by way of examples. In addition, measurement and evaluation of various values in the examples were performed as follows.
(1) Tensile strength (cN / dtex), elongation (%)
Using an autograph AG-1 manufactured by Shimadzu Corporation, the sample length was 25 cm, the tensile speed was 300 mm / min, and the initial load was measured as 1/20 g of the fineness.
(2) Bending wear resistance (times)
A load of 100 g was applied to the obtained multifilament, and it was brought into contact with a round cross-section metal rod with a diameter of 20 mm around 1600 sandpaper at an angle of 90 degrees, traverse speed 6.7 mm / min, stroke speed 35 times / Reciprocating friction was performed under a speed condition of min, and the number of times until the multifilament broke was measured. (Passed over 3000 times)
(3) Twisted yarn strength (N), elongation (%)
Nine obtained multifilaments are twisted (under twisted) at a spindle rotation speed of 4000 rpm and 300 T / M using a ring twisting machine ST-30 type manufactured by Kyoritsu Machinery Co., Ltd. to obtain a twisted yarn. This twisted yarn was measured using an autograph AG-1 type manufactured by Shimadzu Corporation with a sample length of 25 cm, a tensile speed of 300 mm / min, and an initial load of 1/20 g of the fineness.
(4) Twist yarn bending wear resistance (times)
The twisted yarn produced in (3) is wound with a belt abrasion tester in accordance with the abrasion resistance test of JIS D4604 "Automobile parts seat belt", measuring conditions JIS D4604, load 200g, stroke length 330 ± 30mm, 1600 sandpaper Hexagonal bar (angular radius 0.5 ± 0.1mm, width across flats 6.35 ± 0.03mm) is contacted at an angle of 85 ± 2 degrees, and reciprocated at a speed of 30 ± 1 stroke / min. The number of times to break was measured. (Passed 100 times or more)
(5) Operability Spinning, stretching, and winding were continuously performed with 2 spindles for 24 hours, and the operability was evaluated in three stages by the number of yarn breakage during spinning as follows.
Number of thread breaks 0-5 times ○
Number of thread breaks 5-9 times △
Number of thread breaks 10 times or more ×

Example 1
Polylactic acid has a melting point of 170 ° C., a heat of fusion of 38 J / g, a mass ratio (mol% L-lactic acid / D-lactic acid) of 98.5 / 1.5, which is the content ratio of L-lactic acid and D-lactic acid, and a number average. A molecular weight 85000 was used. A master chip was obtained by containing 20% by mass of spherical silicone powder (KMP-590 manufactured by Shin-Etsu Chemical Co., Ltd.) having an average particle size of 2 μm in this polylactic acid.
Next, the master chip and polylactic acid were supplied to an extruder type melt spinning machine so that the silicone powder was 2.0% by mass with respect to the fiber mass, and melt kneaded. After melt spinning at a spinning temperature of 225 ° C. from a spinneret (surface diameter 230 mm, hole diameter 0.35 mm, hole number 140), the yarn was cooled and an oil agent was applied. Subsequently, without drawing once, heat drawing was performed between heat rollers heated to 135 to 145 ° C. at a draw ratio of 6.62 times, and drawn at 2300 m / min to obtain a multifilament having a total fineness of 1100 dtex and 140 filaments.

Examples 2-5, Comparative Examples 1-3
A multifilament of 1100 dtex and 140 filaments was obtained in the same manner as in Example 1 except that the content of the silicone powder in the fiber and the draw ratio were variously changed as shown in Table 1.

Example 6
Polylactic acid has a melting point of 170 ° C., a heat of fusion of 38 J / g, a mass ratio (mol% L-lactic acid / D-lactic acid) of 98.5 / 1.5, which is the content ratio of L-lactic acid and D-lactic acid, and a number average. A silicon powder-containing polylactic acid (master chip and polylactic acid) used in Example 1 was used as a core component with a molecular weight of 85000.
Using an extruder type composite melt spinning machine, the silicone powder content is added to 1.0% by mass with respect to the fiber mass, so that the core-sheath mass ratio (core / sheath) is 50/50. A multifilament having a total fineness of 1100 dtex and 140 filaments was obtained in the same manner as in Example 1 except that the composite fiber was spun and heat-drawn at a draw ratio of 6.42.

Examples 7-8, Comparative Examples 4-5
Example 6 except that the content of the silicone powder in the fiber was changed to the value shown in Table 1 by adjusting the addition amount of the master chip of the sheath component, and the draw ratio was changed to the value shown in Table 1. Similarly, a multifilament of 1100 dtex and 140 filaments was obtained.

  Table 1 shows the characteristic values and evaluation results of the multifilaments obtained in Examples 1 to 8 and Comparative Examples 1 to 5 and the twisted yarns obtained from the multifilaments.

  As is apparent from Table 1, the multifilaments and twisted yarns obtained in Examples 1 to 8 are excellent in wear resistance (flexible wear resistance), have good strength and elongation, and have good operability. I was able to get it.

  On the other hand, since the multifilament of Comparative Example 1 did not contain silicone powder, it was inferior in wear resistance. The multifilaments of Comparative Examples 2 and 4 were inferior in wear resistance because the silicone powder content was too small. Since the multifilaments of Comparative Examples 3 and 5 contained too much silicone powder, the operability was remarkably poor, and fibers could not be obtained.

Claims (1)

A polylactic acid fiber comprising a polylactic acid containing silicone powder as at least one component, and containing 0.1 to 10% by mass of silicone powder with respect to the mass of the fiber.