JP2003286659A - Polylactic acid stereo complex fiber structure excellent in durable water repellency and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid stereo complex fiber structure suppressing hardening of its hand by heat treatment and excellent in durable water repellency. <P>SOLUTION: The polylactic acid stereo complex fiber structure excellent in durable water repellency is composed of a fiber comprising a polylactic acid stereo complex obtained by mixing a poly-L-lactic acid with a poly-D-lactic acid and has a water-repellent resin layer on the surface of the fiber structure. The content of the water-repellent resin is preferably ≥0.2 wt.% based on the weight of the fiber structure. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polylactic acid stereocomplex fiber structure excellent in durable water repellency and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, as interest in environmental problems has increased, aromatic polyesters are not easily decomposed in a natural environment, and therefore biodegradable materials have been required to be substituted from the viewpoint of environmental protection. .

[0003] Aliphatic polyester fibers are being used in various fields because of their biodegradability and good mechanical properties. In particular, poly-L-lactic acid having a high L-lactic acid content is crystalline and has a melting point. Since it has a relatively high melting point among the biodegradable thermoplastics of 170 to 180 ° C., it can be widely used as a fiber for clothing or industrial use.

However, in the process of manufacturing and processing woven or knitted fabrics and nonwoven fabrics, if they are processed under the same conditions as synthetic fibers such as general-purpose polyesters and polyamides, they will remarkably shrink when passing through a heat treatment zone or a heat roll. , And troubles such as being entangled with the roll are likely to occur. Further, when resin processing is performed, depending on the resin, it is not possible to process at a temperature sufficient for film formation due to problems such as curing of polylactic acid fiber, and thus the durability of the film is insufficient. For example,
Fluorine-based water repellents that are commonly used in water-repellent finishing of synthetic fibers such as polyester and polyamide require dry heat treatment at 150 ° C or higher to form a durable film. Since the polylactic acid fiber was cured by dry heat treatment at a temperature of 150 ° C., sufficient treatment could not be performed at the temperature necessary for film formation, and the durability of water repellency was insufficient.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a polylactic acid stereocomplex fiber structure which solves the above problems, suppresses the hardening of the texture by heat treatment, and is excellent in durable water repellency, and a method for producing the same. This is a technical issue.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems and has the following structure. (1) A fiber structure composed of fibers composed of a polylactic acid stereocomplex obtained by blending poly L-lactic acid and poly D-lactic acid, and having a water-repellent resin layer on the surface of the fiber structure. A polylactic acid stereocomplex fiber structure excellent in durability and water repellency, which is characterized in that (2) The content of the water-repellent resin is 0.
The polylactic acid stereocomplex fiber structure having excellent durability and water repellency according to the above (1), which is 2% by mass or more. (3) In producing the polylactic acid stereocomplex fiber structure excellent in durable water repellency according to the above (1) or (2), curing after water repellent treatment is performed at a temperature of 150 ° C. or higher. A method for producing a polylactic acid stereocomplex fiber structure excellent in durable water repellency.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. First, the polylactic acid stereocomplex mainly constituting the fiber structure of the present invention will be described. Poly-L-lactic acid has a left-handed helical structure, while poly-L-lactic acid
Since D-lactic acid has a right-handed helical structure, if these are uniformly mixed, a stereospecific bond occurs between the two components, and poly-L-lactic acid or poly-D-lactic acid is formed alone. Form a tighter and stronger crystal structure than the crystal structure. This crystal structure is called a stereo complex. Due to the formation of this stereo complex, the melting point of the polylactic acid-based polymer becomes high and the heat shrinkage rate becomes low.

The polylactic acid stereocomplex is L-
Poly-L-lactic acid containing lactic acid as a main component and poly-D-lactic acid containing D-lactic acid as a main component are mixed in a solution state or a molten state to form a stereospecific bond between these two components. Can be formed by. For example, Poly-L
-Lactic acid and poly-D-lactic acid are respectively dissolved in a solvent such as methylene chloride, chloroform, ethane chloride, N-methylpyrrolidone, dimethylformamide, tetrahydrofuran, butyrolactone, trioxane, and mixed and stirred, and then the solvent is heated under reduced pressure. It can be formed by removing. Further, the chips of poly-L-lactic acid and poly-D-lactic acid can be formed by mixing and melting and kneading them with a biaxial extruder.

The polylactic acid stereocomplex used in the present invention is formed by blending poly L-lactic acid and poly D-lactic acid. Here, poly-L-lactic acid means
It is composed of 70 to 100 mol% of L-lactic acid and 0 to 30 mol% of D-lactic acid or a copolymer other than D-lactic acid, while poly-D-lactic acid is 70 to 70 mol% of D-lactic acid. 100
Mol% and L-lactic acid or copolymer other than L-lactic acid 0 to 30
And mol%.

Examples of the copolymerization monomer component other than L, D-lactic acid include oxyacids, lactones, dicarboxylic acids, polyhydric alcohols and the like which can be copolymerized with lactic acid monomers or lactide. Further, various polyesters, polyethers, polycarbonates and the like which are composed of these components and have a functional group capable of forming an ester bond are also included.

In the polylactic acid stereocomplex used in the present invention, the blending ratio of poly-L-lactic acid and poly-D-lactic acid is not particularly limited, but the mass ratio is 2: 3.
To 3: 2, more preferably 1: 1 in order to improve the content of the stereocomplex crystal.

Further, the polylactic acid stereocomplex used in the present invention has a differential scanning calorimetry (DSC: Diff).
initial Scanning Colorime
Those which exhibit certain characteristics when subjected to a trey) are preferable, that is, the high temperature crystalline melting phase occupies 90% or more of the entire crystalline phase, and the melting initiation temperature of the high temperature crystalline melting phase is 190%.
It is preferably at least ° C.

FIG. 1 shows a melting endothermic curve (DSC curve) when fibers made of the polylactic acid stereocomplex used in the present invention are subjected to differential scanning calorimetry. In the melting endotherm curve (a), the heat quantity of the endothermic peak (heat quantity of crystal fusion)
Indicates the amount of the crystalline phase of the polymer, and this endothermic amount is
It is represented by the shaded area in the figure.

The polylactic acid stereocomplex usually exhibits at least two endothermic peaks depending on the constituents or composition ratios of the constituting polymer components, the preparation conditions of the stereocomplex, and the formation state, and two crystalline phases are formed. Indicates that it exists. One is a low temperature crystalline melting phase (X) observed at 165 to 180 ° C., which is a melting point peculiar to each polymer component such as poly-L-lactic acid and poly-D-lactic acid, and the other is stereo. It is a high temperature crystalline melting phase (Y) at 190 to 230 ° C. which is recognized as the complex is formed.

The relative proportions of the high-temperature crystal melting phase and the low-temperature crystal melting phase are calculated from the respective crystal fusion heat amounts, that is, the area sizes represented by the two endothermic peaks of the melting endothermic curve (a). can do. Therefore,
The ratio of the high temperature crystal melting phase to the entire crystal phase is calculated by the following formula (1). Ratio (%) of high-temperature crystal-melting phase to the whole crystal phase = Y × 100 / (Y + X) (1) where X: area represented by endothermic peak of low-temperature crystal-melting phase Y: high-temperature crystal-melting phase Area represented by endothermic peak

When the ratio of the high temperature crystalline melting phase to the entire crystalline phase is less than 90%, when the fiber structure composed of the fibers made of this polylactic acid stereocomplex is heat treated, the fibers are softened and partly. Melting may start and the texture of the fiber structure tends to become hard, which is not preferable. Further, when the fiber structure is a woven or knitted fabric or a non-woven fabric, there is a problem that the fiber shrinks or is entangled with the heat roll due to heat treatment such as passing through a heat treatment zone or a heat roll during manufacturing / processing. It is not preferable because it tends to occur.

Next, regarding the melting start temperature of the high temperature crystal melting phase, this is the onset temperature of the endothermic peak of the high temperature crystal melting phase and the endothermic peak D of the low temperature side.
It is the temperature at the point where the tangent line drawn at the maximum slope of the SC curve and the straight line extending the low temperature side baseline to the high temperature side intersect. More specifically, it is an onset temperature displayed when automatically measured at a temperature rising rate of 20 ° C./min using Pyris 1 manufactured by Perkin Elmer.

When the melting start temperature of the high temperature crystalline melting phase of the polylactic acid stereocomplex used in the present invention is less than 190 ° C., when the fiber structure composed of the fibers of the polylactic acid stereocomplex is subjected to heat treatment,
The fibers may soften and start to partially melt, and the texture of the fiber structure tends to become hard, which is not preferable. Also,
When the fiber structure is a woven or knitted fabric or a non-woven fabric, it is easy to cause troubles such as fiber shrinkage or entanglement with the heat roll due to heat treatment such as passing through a heat treatment zone or a heat roll during manufacturing / processing. Become.

The melting start temperature of the high temperature crystalline melting phase of the polylactic acid stereocomplex used in the present invention is preferably 190 ° C. or higher, more preferably 210 ° C. or higher.
In the polylactic acid stereocomplex used in the present invention, the ratio of the high-temperature crystal melting phase to the entire crystal phase may be 100%, and the polylactic acid stereocomplex may be composed of only the high-temperature crystal melting phase having a melting start temperature of 190 ° C. or higher. .

The hot water shrinkage of the fiber comprising the polylactic acid stereo complex used in the present invention is preferably 10% or less, more preferably 5% or less. Hot water shrinkage is 1
When it exceeds 0%, when a fiber product such as a woven or knitted fabric or a non-woven fabric is formed using such a fiber having a high hot water shrinkage ratio, the fiber shrinks in the processing step to harden the texture, or the flat surface quality. Is difficult to obtain, which is not preferable.

In the present invention, the hot water shrinkage ratio means that a fiber having a length of 50 mm is immersed in boiling water (100 ° C.) for 15 minutes, and then the length after immersion (N mm) is measured. Calculated according to 2). Hot water shrinkage rate (%) = [(50−N) / 50] × 100 (2) The fiber made of the polylactic acid stereocomplex used in the present invention is obtained as follows. You can

In the polylactic acid stereocomplex, the ratio of the high temperature crystalline melting phase to the entire crystal phase depends on the composition ratio of L-lactic acid and D-lactic acid, which are symmetric constituents, and on the preparation and formation conditions of the stereocomplex. . The composition ratio of L-lactic acid and D-lactic acid is close to 1: 1,
Further, the ratio of the high temperature crystal melting phase can be increased by uniformly mixing the poly-L-lactic acid and the poly-D-lactic acid in a solution state or a molten state at the molecular level.

Poly-L-lactic acid and poly-D-lactic acid are mixed in a solution state or a molten state, or poly-L-lactic acid
A stereo complex is formed by mixing and melting and kneading chips of lactic acid and poly-D-lactic acid in a biaxial extruder, and thereafter, fibers are formed by melt spinning or solvent spinning.

Then, the obtained fiber is heated at a temperature lower than the melting start temperature of the high temperature crystal melting phase and in a temperature range that promotes crystallization, that is, 120 to 190 ° C., more preferably 160 to 175 ° C. set. This heat setting promotes crystallization, increasing the proportion of the high temperature crystal melting phase,
It is possible to improve the melting start temperature of the high temperature crystal melting phase and reduce the hot water shrinkage rate. This heat setting is performed at the time of stretching or false twisting of the fiber made of the polylactic acid stereocomplex, or after that. It is possible to perform heat setting at such a high temperature because the polylactic acid stereocomplex has a crystalline melting point as high as 190 to 230 ° C., and the melting point as in conventional mere poly-L-lactic acid is 170. This is not possible with a temperature of about ℃.

The fiber made of the polylactic acid stereocomplex described above can be used in the form of, for example, monofilament, multifilament, short-cut fiber, staple, etc. Further, even if the cross-sectional shape is a round cross section, it is an atypical cross section. It may be hollow or non-hollow. Furthermore, the single yarn fineness is not particularly limited and may be determined according to the required characteristics depending on the application, but is about 0.5 to 200 decitex. The form of the fibers may be crimped. For use as a cushioning material or the like, one having a conjugate type three-dimensional crimp composed of two kinds of polylactic acid stereocomplexes having different polymerization degrees and copolymerization rates is preferable. Fibers composed of polylactic acid stereocomplex, particularly when applied with a dry non-woven fabric oil agent for polyester fibers, a wet non-woven fabric oil agent or a spinning oil agent, are particularly slippery silicone-based or non-silicone lubricants. May be given.

The fibrous structure of the present invention comprises a woven fabric, a knitted fabric, a net, a spun yarn, a braid, a wet papermaking sheet produced by dispersing short-cut fibers in water, a spunbonded non-woven fabric, and a short fiber. Which is obtained by opening the staples by a card machine or the like to accumulate the staples, a short fiber non-woven fabric in which fibers are entangled by subjecting the webs to needling processing and spunlacing, and the web is a heat embossing device. A heat-bonded nonwoven fabric or the like in which fibers are heat-bonded by heat treatment using a thermocompression bonding device, a hot air treatment device, or the like.

The above-mentioned fiber structure may consist only of polylactic acid stereocomplex fibers, but polylactic acid stereocomplex fibers and natural fibers such as cotton, wool and hemp, rayon, solvent-spun cellulose fibers and the like. Recycled fibers, synthetic fibers such as polyester, nylon, acrylic, etc. may be mixed to prepare a mixed yarn, a mixed yarn, a mixed knitted fabric, a mixed cotton non-woven fabric or the like.

Further, the fiber structure of the present invention has a water repellent resin layer on its surface. The water-repellent resin layer referred to here is a commonly used padding method, spray method, or the like, using a known water-repellent agent such as a fluorine-based water repellent, a paraffin-based water repellent, and a polysiloxane-based water repellent. It is formed by performing a drying process and a curing process after being processed by a known method. When particularly good water repellency is required, a compound such as an acrylic ester or a methacrylic ester containing a perfluoroalkyl group is used as a water repellent,
A method of impregnating a fiber structure in an aqueous dispersion prepared so as to contain 0.2% by mass or more with respect to the fiber mass, and then drying after squeezing with a mangle, or after spraying the aqueous dispersion and drying. A known method may be used in which a water repellent is added to the fiber structure by a method or the like and then the fiber structure is cured.

The curing is preferably performed at a temperature of 150 ° C. or higher. Curing temperature is 150
When the temperature is lower than 0 ° C, the formation of the water-repellent resin film may be insufficient and durability is deteriorated, which is not preferable. Further, a melamine-based, isocyanate-based, imine-based crosslinking agent or the like may be used in combination with the water-repellent agent in order to improve the water-repellent durability.
Further, an antistatic agent or a softening agent for suppressing the generation of static electricity, and various finishing agents for imparting other functions may also be used in combination as long as the durable water repellency is not deteriorated.

[0030]

Since the fiber structure of the present invention is composed of fibers made of polylactic acid stereocomplex, its heat resistance is improved, and curing at the time of water repellent treatment is performed at a temperature sufficient to form a water repellent resin film. It can be performed. for that reason,
It has durable water repellency and retains excellent water repellency even after repeated washing.

[0031]

EXAMPLES Next, the present invention will be specifically described by way of examples, but the present invention is not limited to these. Moreover, the measurement and evaluation in the examples were carried out by the following methods. (1) Thermal characteristics Perkin Elmer's Pyris 1 was used, and from the DSC curve when automatically measured at a heating rate of 20 ° C / min, the ratio of the high temperature crystalline melting phase, the melting start temperature of the high temperature crystalline melting phase, the high temperature The melting temperature of the crystalline melting phase was determined. (2) Water repellency Measured by JIS L-1092 spray method. (3) Washing method It was measured according to JIS L-0217 103 method. (4) A sensory test based on feeling handling was performed and evaluated according to the following criteria. A: Very good, with no texture hardening. B: There is almost no hardening of the texture and it is good. C: Hardness of texture is clearly observed.

Example 1 Polylactic acid containing L-lactic acid as a main component and having a number average molecular weight of 72,000 (L-lactic acid unit: 98.8%, D-lactic acid unit:
1.2%) and polylactic acid containing D-lactic acid as a main component and having a number average molecular weight of 68,000 (L-lactic acid unit: 1.4%, D
-Lactic acid unit: 98.6%) is melt-kneaded with a twin-screw extruder at 200 to 230 ° C. for about 10 minutes with the same mass, and then extruded in water into a strand shape, and chips are produced. did.

Next, using this chip, a spinning temperature of 225
Melt spinning was carried out at a spinning speed of 3000 m / min from a spinneret having a round hole at ℃. Subsequently, the film was drawn at a drawing temperature of 120 ° C. and a draw ratio of 1.3 to obtain a polylactic acid stereocomplex fiber having 110 decitex 36 filaments. Next, false twisting was performed at a heater temperature of 120 ° C. to obtain a polylactic acid stereocomplex false twisted yarn of 84 decitex 36 filaments. Regarding the thermal characteristics of the obtained false twist textured yarn, the ratio of the high temperature crystal melting phase was 92%, the melting start temperature of the high temperature crystal melting phase was 193 ° C, and the melting temperature of the high temperature crystal melting phase was 204 ° C.

Next, two double twisted yarns (500 times / m) of polylactic acid stereocomplex false twisted yarns were used as warp yarns.
84 decitex 36 filament polylactic acid stereocomplex false twisted yarn 4 plied yarn (150 times /
m) was used as the weft, and a plain woven fabric was woven with a warp density of 95 / 2.54 cm and a weft density of 45 / 2.54 cm. Subsequently, this woven fabric was scoured at 80 ° C. for 20 minutes in a bath containing 1 g / l (l) of a surfactant and dried at 130 ° C.
After pre-setting at 50 ° C. for 1 minute and dyeing with a recipe of the following formulation 1 in a jet dyeing machine at 120 ° C. for 30 minutes,
It was dried at 130 ° C.

[0035] (Prescription 1)   Cibacet Blue EL-FG 0.5% omf   (Ciba Specialty Chemicals Co., Ltd .: Disperse dye)   Nikka Sunsalt SN-130 0.5g / l   (Nichika Chemical Co., Ltd .: Dispersant)   Acetic acid (48%) 0.2 cc / l

Then, the above fabric was impregnated with an aqueous solution of the following formulation 2 using a padder, and the solution was squeezed with a mangle under the condition of a squeezing ratio of 46%, followed by drying at 130 ° C., followed by a temperature of 150.
The woven fabric of Example 1 was obtained by performing curing under conditions of ° C and a time of 45 seconds.

[0037] (Prescription 2)   Asahi Guard AG-925 8% by mass   (Fluorine-based water repellent manufactured by Asahi Glass Co., Ltd.)   Sumitex Resin M-3 0.3% by mass   (Sumitomo Chemical Co., Ltd., melamine resin)   Sumitex Accelerator ACX 0.3% by mass   (Sumitomo Chemical Co., Ltd., melamine resin catalyst)

Example 2 Polylactic acid containing L-lactic acid as a main component (L-lactic acid unit: 99)
Mol%, D-lactic acid unit: 1 mol%, melting point: 169 ° C., relative viscosity: 1.885), and polylactic acid containing D-lactic acid as a main component (L-lactic acid unit: 1 mol%, D -Lactic acid unit: 99 mol%, melting point: 168 ° C, relative viscosity: 1.
901) and the same amount of chips were mixed and dried under reduced pressure with stirring.

Using a conventional melt spinning apparatus, the mixed chips thus obtained were subjected to a spinning temperature of 235 ° C. through a spinneret having a round hole,
Melt spinning was performed at a spinning speed of 1000 m / min. Subsequently, stretching is carried out at a stretching temperature of 130 ° C. and a stretching ratio of 2.9, and 110
A polylactic acid stereocomplex fiber having 36 decitex filaments was obtained. Next, false twisting was performed at a heater temperature of 120 ° C. to obtain a polylactic acid stereocomplex false twisted yarn of 84 decitex 36 filaments. Regarding the thermal characteristics of the obtained false twisted yarn, the ratio of the high temperature crystal melting phase was 99%, the melting start temperature of the high temperature crystal melting phase was 206 ° C, and the melting temperature of the high temperature crystal melting phase was 218 ° C.

The obtained false twisted yarn was woven, scoured, preset and dyed in the same manner as in Example 1 and the curing method was changed to 160 ° C. in the same manner as in Example 1. Water repellent treatment was performed to obtain the woven fabric of Example 2.

Comparative Example 1 Instead of a chip in which poly L-lactic acid and poly D-lactic acid were blended in equal mass, polylactic acid containing L-lactic acid as a main component and having a number average molecular weight of 72,000 (L-lactic acid unit: 98.8
%, D-lactic acid unit: 1.2%) Example 1 except that the heater temperature during false twisting was changed to 100 ° C.
A poly-L-lactic acid false twist textured yarn was obtained by the same method as described above. Regarding the thermal properties of the obtained false twisted yarn, the proportion of the high temperature crystal melting phase is 0.
%, The melting start temperature of the high temperature crystal melting phase was 169 ° C., and the melting temperature of the high temperature crystal melting phase was 181 ° C. Next, the dyeing temperature is 110 ° C., and the curing temperature after the water repellent treatment is 130.
A woven fabric of Comparative Example 1 was obtained in the same manner as in Example 1 except that the temperature was changed to ° C.

Comparative Example 2 A woven fabric of Comparative Example 2 was obtained in the same manner as in Example 1 except that the poly L-lactic acid false twist textured yarn of Comparative Example 1 was used and the dyeing temperature was changed to 110 ° C. Table 1 shows the evaluation results of the woven fabrics obtained in Examples 1 and 2 and Comparative Examples 1 and 2.

[0043]

[Table 1]

As is clear from Table 1, the woven fabrics (fibrous structures) of Examples 1 and 2 have excellent water repellency even after 20 times of home washing, and there is no hardening of the woven fabrics, which is excellent. It had a texture.

On the other hand, since the woven fabrics of Comparative Examples 1 and 2 use the polylactic acid fiber containing L-lactic acid as a main component, the texture of the woven fabrics can be obtained by lowering the curing temperature after the water repellent treatment (Comparative Example 1). Is good, but the water repellency after 20 times of home washing is poor, and when the curing temperature after the water repellent treatment is increased (Comparative Example 2), the water repellency after 20 times of home washing is excellent, but the fabric Was hardened and had a hard texture.

[0046]

The fiber structure of the present invention is excellent in heat resistance because it is composed of polylactic acid stereocomplex fiber, and has a texture even when cured at a temperature of 150 ° C. or higher during the water repellent treatment. It is possible to obtain a fibrous structure having excellent durability and water repellency without being cured. Therefore, it can be favorably used for sports clothes, ski wear, mountain wear and the like mainly for outdoor activities, outerwear such as coats and blouson, rain clothes, umbrellas, bags and the like.

[Brief description of drawings]

FIG. 1 is a graph showing an example of a melting endothermic curve (DSC curve) of a fiber made of a polylactic acid-based polymer forming a stereo complex.

[Explanation of symbols]

a Melting endotherm curve X Low temperature crystalline melting phase Y High temperature crystal melting phase

Claims (3)

[Claims] 1. A fiber structure comprising fibers of a polylactic acid stereocomplex obtained by blending poly L-lactic acid and poly D-lactic acid, and having a water-repellent resin layer on the surface of the fiber structure. A polylactic acid stereocomplex fiber structure with excellent durability and water repellency. 2. The polylactic acid stereocomplex fiber structure excellent in durable water repellency according to claim 1, wherein the content of the water repellent resin is 0.2% by mass or more based on the mass of the fiber structure. object. 3. When producing a polylactic acid stereocomplex fiber structure excellent in durable water repellency according to claim 1 or 2, curing after water repellent treatment is performed at a temperature of 150 ° C. or higher. A method for producing a polylactic acid stereocomplex fiber structure having excellent durability and water repellency.