JP2003105629A - Polylactic acid stereo complex fiber excellent in heat resistance and textile product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid-based fiber, wherein textile products consisted of the fiber, such as textiles and nonwoven fabrics, can be well heat- treated in its production and treatment and feeling of the textile products is not damaged when ironed, and to provide textile products comprising the fiber. SOLUTION: This polylactic acid stereo complex fiber excellent in heat resistance is a fiber comprising polylactic acid polymer, wherein the polymer forms a stereo complex, has >=90% high temperature crystal fused phase based on whole crystal phase, >=190 deg.C melting starting temperature of the high temperature crystal fused phase and <=10% hot water shrinkage. And the textile product using the fiber is also provided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polylactic acid stereocomplex fiber having excellent heat resistance and a fiber product containing the fiber.

[0002]

2. Description of the Related Art A technique for making polylactic acid, which is a thermoplastic, into fibers by a melt spinning method is known. In particular, poly-L-lactic acid having a high L-lactic acid content is crystalline and has a melting point of 170 to Since it has a relatively high melting point of 180 ° C. among thermoplastics having biodegradability, it can be widely used as a fiber for clothing or industrial use.

However, when it is used as a fiber for clothing, for example, when it is ironed like a synthetic fiber such as general-purpose polyester or polyamide, the texture is hard even if the fiber is not melted. I have a problem. Therefore, when ironing a cloth made of polylactic acid fiber, it is necessary to set a particularly low temperature and be extremely careful, and there is a serious problem that the application to the field of clothing is significantly limited.

In the process of manufacturing and processing a woven or knitted fabric or a non-woven fabric, problems such as remarkable shrinkage or entanglement with rolls are likely to occur when passing through a heat treatment zone or a heat roll.

By the way, a polylactic acid stereocomplex in which poly-L-lactic acid and poly-D-lactic acid are stereospecifically bound and fibers thereof are known as polylactic acid having a higher melting point. For example, JP-A-63-2649
Japanese Unexamined Patent Publication No. 13 discloses a polylactic acid fiber produced by spinning and drawing from a blend of poly-L-lactic acid and poly-D-lactic acid.

JP-A-63-241024 describes a poly (R-lactide) part bonded to a poly (S-lactide) part, wherein at least one of the above parts is a copolymer. Disclosed are some polylactide compositions.

Further, Japanese Patent Application Laid-Open No. 4-501109 discloses a polymer composition having poly (R-lactide) segments interdigitated with poly (S-lactide) segments and having a biological activity. The drag that holds the part
Threads and devices for delivery are disclosed.

Further, Japanese Patent Laid-Open No. 2000-17163 discloses that an amorphous polymer containing poly-L-lactic acid as a main component and an amorphous polymer containing poly-D-lactic acid as a main component are melt-blended. The resulting polylactic acid stereocomplex composition is disclosed.

The melting point of the above-disclosed polylactic acid stereocomplex is 10 to 60 ° C. higher than that of ordinary poly-L-lactic acid. However, even though these are stereocomplex fibers having a high melting point, the above-mentioned ironing characteristics are not necessarily improved, and even if the melting point is actually 30 ° C. or more higher than that of the conventional poly-L-lactic acid fiber. Nevertheless, it has been observed that the texture is still hard.

[0010]

DISCLOSURE OF THE INVENTION The present invention is to solve the above-mentioned problems, and it is possible to satisfactorily perform heat treatment in the manufacturing and processing steps of textile products such as woven and knitted fabrics and nonwoven fabrics made of polylactic acid fibers. It is an object of the present invention to provide a polylactic acid-based fiber and a fiber product made of the same, which is possible and does not harden the texture when ironed on the fiber product made of the polylactic acid-based fiber.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present inventor has conducted earnest studies on the thorough investigation of the cause of hardening of the texture of the polylactic acid fiber during ironing and its countermeasures.

[0012] In the process of investigating the cause of the hardening of the texture of the polylactic acid-based fiber during ironing, it is important that the polylactic acid stereocomplex fiber first has a high abundance ratio of the high-temperature crystalline melting phase. Moreover, it has been found that the phenomenon that the polylactic acid-based fiber is hardened by the heat treatment is closely related to the melting start temperature of the high temperature crystal melting phase. Then, the abundance ratio of the high temperature crystal melting phase in the polylactic acid stereocomplex fiber is set to a specific range,
Moreover, the subject could be achieved by setting the melting start temperature of the high temperature crystal melting phase to a specific temperature.

That is, the present invention is a fiber comprising a polylactic acid-based polymer, wherein the polymer forms a stereo complex, and the high temperature crystal melting phase of the polymer accounts for 90% or more of the entire crystal phase. A polylactic acid stereocomplex fiber excellent in heat resistance, characterized by having a melting start temperature of a high temperature crystal melting phase of 190 ° C. or higher and a hot water shrinkage ratio of 10% or lower. .

The present invention also provides a fiber product characterized by containing the above-mentioned polylactic acid stereocomplex fiber.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The polylactic acid stereocomplex fiber of the present invention is a fiber made of a polylactic acid-based polymer, and the polymer forms a stereocomplex.

In the present invention, the polylactic acid-based polymer forming a stereocomplex is a poly-L-lactic acid containing L-lactic acid as a main component and a poly-lactic acid containing D-lactic acid as a main component.
Composed of D-lactic acid.

Here, poly-L-containing L-lactic acid as a main component
Lactic acid means 70-100 mol% of L-lactic acid and D-lactic acid or
It is composed of 0 to 30 mol% of a copolymer other than D-lactic acid, while poly-D-containing D-lactic acid as a main component.
Lactic acid means 70-100 mol% of D-lactic acid and L-lactic acid or
It is composed of 0 to 30 mol% of a copolymer other than L-lactic acid.

Examples of copolymerizable monomer components other than D, L-lactic acid include oxyacids, lactones, dicarboxylic acids, and polyhydric alcohols which are copolymerizable 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.

Next, the stereocomplex formed by the polylactic acid polymer will be described. Poly-L-lactic acid has a left-handed helix structure, whereas poly-D-lactic acid has a right-handed helix structure. Therefore, when these are uniformly mixed at the molecular level, a stereospecific bond between the two components is formed. Occurs, and forms a tighter and stronger crystal structure than the crystal structure formed in the case of poly-L-lactic acid or poly-D-lactic acid alone. This crystal structure is called a stereo complex. Due to the formation of this stereo complex,
The polylactic acid-based polymer has a high melting point and a low heat shrinkage ratio.

The stereocomplex in the polylactic acid polymer is obtained by mixing the poly-L-lactic acid having L-lactic acid as a main component and the poly-D-lactic acid having D-lactic acid as a main component in a solution state or a molten state. Then, it can be formed by causing a stereospecific bond between these two components.
For example, poly-L-lactic acid and poly-D-lactic acid are respectively methylene chloride, chloroform, ethane chloride, N-methylpyrrolidone, dimethylformamide, tetrahydrofuran,
It can be formed by dissolving in a solvent such as butyrolactone or trioxane, mixing and stirring, and then removing the solvent under heating and reduced pressure. In addition, the chips of poly-L-lactic acid and poly-D-lactic acid are mixed and melted with a biaxial extruder.
It can be formed by kneading. The mixing ratio of these two components is preferably such that the L-lactic acid unit and the D-lactic acid unit are substantially 1: 1.

The polylactic acid-based polymer formed by forming the stereocomplex constituting the fiber of the present invention exhibits certain characteristics when subjected to differential scanning calorimetry, that is, the high temperature crystalline melting phase is the crystalline phase. Account for over 90% of the total,
Moreover, the melting start temperature of the high temperature crystal melting phase is 190 ° C. or higher.

FIG. 1 shows a fiber made of a polylactic acid-based polymer forming the stereocomplex of the present invention, which was analyzed by differential scanning calorimetry (DSC: Differential Sca).
3 shows a melting endotherm curve (DSC curve) when performing "Ning Calorimetery". 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.

In a polylactic acid-based polymer formed by forming a stereocomplex, at least two endothermic peaks are ordinarily used depending on the kind or composition ratio of constituent polymer components, the preparation conditions of the stereocomplex, and the formation state. Indicates that two crystalline phases are present. The first is 165 to 180 ° C, which is the melting point peculiar to each polymer component such as poly-L-lactic acid and poly-D-lactic acid.
The low temperature crystalline melting phase (X) observed in Fig. 2 is the other, which is recognized with the formation of the stereocomplex.
230 ° C. high temperature crystalline melting phase (Y).

The relative proportions of the high temperature crystalline melting phase and the low temperature crystalline melting phase are calculated from the respective amounts of heat of crystalline melting, that is, the areas of 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. Ratio (%) of high-temperature crystal melting phase to total crystal phase = Y ×
100 / (Y + X) In the above formula, Y is the area represented by the endothermic peak of the high temperature crystalline melting phase, and X is the area represented by the endothermic peak of the low temperature crystalline melting phase.

When the ratio of the high temperature crystalline melting phase to the entire crystalline phase is less than 90%, when the fiber product made of this fiber is ironed, the fiber may soften and may partially melt. The texture of the product becomes hard, which is not preferable. We also manufacture woven and knitted fabrics and non-woven fabrics using this fiber.
At the time of processing, when heat treatment such as passing through a heat treatment zone or a heat roll is performed, the fiber is likely to shrink, and the trouble of being entangled with the heat roll is likely to occur, so that the object of the present invention is achieved. It is not possible because it is not possible.

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 D on the low temperature side of the endothermic peak.
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 polymer forming the stereocomplex forming the fiber of the present invention is less than 190 ° C., the fiber product made of this fiber is ironed. When this is done, the fibers may soften and begin to partially melt, and the texture of the fiber product becomes hard, which is not preferable. Further, when manufacturing or processing a woven or knitted fabric or a non-woven fabric using this fiber, the fiber shrinks or is entangled with the heat roll when a heat treatment such as passing through a heat treatment zone or a heat roll is performed. That trouble is likely to occur.

In the present invention, the melting start temperature of the high temperature crystalline melting phase of the polylactic acid polymer formed by forming the stereocomplex forming the fibers is 190 ° C. or higher, preferably 210 ° C. or higher.

In the polylactic acid-based polymer which constitutes the fiber of the present invention, the ratio of the high temperature crystalline melting phase to the entire crystalline phase is 100%, and only the high temperature crystalline melting phase having a melting start temperature of 190 ° C. or higher is used. It may be

The hot water shrinkage of the fiber made of the polylactic acid polymer of the present invention is 10% or less, preferably 5% or less. When the hot water shrinkage ratio exceeds 10%, when a fiber product such as a woven or knitted fabric or a non-woven fabric is produced using such a fiber having a high hot water shrinkage ratio, the fibers shrink in the processing step and the texture is poor. Also, when the iron is ironed after being made into a textile product, especially when the iron is applied with steam, the fibers shrink due to the heat,
Loss of proper play (misalignment) in the texture and structure of the textile product, which reduces drapeability and makes the texture harder.

The hot water shrinkage ratio of the present invention is 100
A fiber having a length of 50 mm is dipped in (° C.) for 15 minutes, and the length (N (mm)) after the immersion is measured and calculated by the following formula.

Hot water shrinkage (%) = ((50-N) / 5
0) x 100

The fiber made of the polylactic acid-based polymer which forms the above-mentioned stereocomplex of the present invention can be obtained as follows.

In the polylactic acid type polymer formed by forming a stereo complex, 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 the constituents, and the stereo ratio. Preparation of complex
Depends on formation conditions. The composition ratio of L-lactic acid and D-lactic acid is 1
The ratio of the high-temperature crystal melting phase can be increased by bringing the poly-L-lactic acid and the poly-D-lactic acid into a close relationship to 1 and mixing them uniformly at a molecular level in a solution state or a molten state.

Poly-L-lactic acid and poly-D-lactic acid are mixed in a solution state or a molten state, or chips of poly-L-lactic acid and poly-D-lactic acid are mixed and melted and kneaded in a twin-screw extruder, respectively. By doing so, a stereo complex is formed, 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,
The melting start temperature of the high temperature crystal melting phase can be improved and the hot water shrinkage can be suppressed. This heat setting is performed during or after the drawing or false twisting of the polylactic acid stereocomplex fiber. It is possible to perform heat setting at such a high temperature because the polylactic acid-based polymer forming the stereo complex has a high crystal melting point such as 190 to 230 ° C.
-It was not possible with lactic acid having a melting point of about 170 ° C.

The polylactic acid stereocomplex fiber of the present invention can be used in the form of, for example, a monofilament, a multifilament, a short cut fiber or a staple.

The polylactic acid stereocomplex fiber may have a round cross section, a modified cross section, or a hollow or non-hollow cross section. Furthermore, the 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 made of a polylactic acid-based polymer formed by forming two kinds of stereocomplexes having different polymerization degrees and copolymerization rates is preferable. The polylactic acid stereocomplex fiber is provided with an oil agent for dry non-woven fabric, an oil agent for wet non-woven fabric, or an oil agent for spinning, which is particularly slippery, to the polylactic acid stereocomplex fiber. May be.

Further, the fiber product 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. A web formed by stacking staples by opening a staple with a card machine, etc.
The web is subjected to a needling process, a spunlace process, and a short fiber non-woven fabric in which the fibers are entangled with each other. The web is subjected to heat treatment using a hot embossing device, a thermocompression bonding device, a hot air treatment device, etc. It is a heat-bonded nonwoven fabric or the like that is heat-bonded.

When the short fiber non-woven fabric is used as a cushion material or a filter, the thickness is preferably 5 mm or more. The upper limit of the thickness is not particularly limited, but about 150 mm is preferable from the viewpoint of manufacturing equipment, manufacturing cost, and ease of use. The density of the cushion material is 0.01 g / cm ³
The above is preferable. In order to control the thickness and density of the non-woven fabric, it is possible to appropriately select the punch density by the needling process and to heat-compress at a temperature of about (melting point −5) ° C.

The fiber product may be composed only of polylactic acid stereocomplex fiber, but polylactic acid stereocomplex fiber and regenerated fiber such as natural fiber such as cotton, wool and hemp, rayon and solvent-spun cellulose fiber. , Synthetic fibers such as polyester, nylon, and acrylic can be mixed to form a mixed yarn, a mixed yarn, a mixed knitted fabric, a mixed cotton nonwoven fabric, and the like.

[0042]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

Examples 1-5, Comparative Examples 1-2 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).
Lactic acid unit: 98.6%) was melt-kneaded with a twin-screw extruder at 200 to 230 ° C. for about 10 minutes, and then extruded into water in a strand shape to perform cutting, thereby producing a chip.

Next, using this chip, melt spinning was performed at 225 ° C. at a spinning speed of 3000 m / min. To obtain a fiber, which was drawn at a draw ratio at the temperature shown in Table 1 and temporarily set at the temperature shown in Table 1. Twisted. Then, for Example 4 and Comparative Example 3, heat setting was performed at 165 ° C.

Thermal properties of various polylactic acid stereocomplex fibers obtained in Examples 1 to 5 and Comparative Examples 1 to 2 (high temperature crystal melting phase ratio, high temperature crystal melting phase melting start temperature, high temperature crystal melting phase melting point) Table 1 shows the spinning conditions and the ironing characteristics evaluated by the following methods.

(Thermal property) It was determined from a DSC curve when automatically measured at a temperature rising rate of 20 ° C./min using Pyris 1 manufactured by Perkin Elmer.

(Ironing characteristics) The obtained Examples 1 to 5,
Various polylactic acid stereocomplex fibers of Comparative Examples 1 to 3 were made into a multifilament of 84 decitex / 36 filaments, and this multifilament was knitted by a cylinder knitting machine having 270 needles to prepare a cylinder knit sample. . Water was sprayed so that the entire tubular knit sample was uniformly wet, and the texture after ironing with an iron set to a surface temperature of 180 ° C was evaluated by five panelists based on the following criteria. . A: Very good, without hardening of texture. B: There is almost no hardening of the texture and it is good. C: Hardness of texture is clearly observed.

[0048]

[Table 1]

Example 6 Polylactic acid consisting mainly of L-lactic acid (L-lactic acid unit: 99 mol%, D-lactic acid unit: 1 mol%, melting point 169 ° C., relative viscosity (equal mass mixture of phenol and ethane tetrachloride) As a solvent and a sample concentration of 0.5 g / dl and a temperature of 20 ° C.):
1.885) and polylactic acid mainly composed of D-lactic acid (L-lactic acid unit: 1 mol%, D-lactic acid unit: 9
An equal mass of a chip composed of 9 mol%, a melting point of 168 ° C. and a relative viscosity of 1.901) was mixed and dried under reduced pressure with stirring.

Using the usual melt spinning equipment, the obtained mixed chips were subjected to a spinning temperature of 235 ° C. and a total discharge amount of 313 g /
It was melt-spun as a minute. The spun yarn was cooled and then taken off at a take-off speed of 1000 m / min to obtain an undrawn fiber yarn. The obtained yarns were bundled, made into a tow of 110,000 decitex, drawn at a draw ratio of 2.9 and a draw temperature of 80 ° C.
After heat-setting with a heat drum at ℃, crimp it using a push-down crimper, cut it to a length of 51 mm, the high-temperature crystal melting phase ratio 99%, the high-temperature crystal melting phase melting start temperature 206 ℃, melting point 218 of high temperature crystal melting phase
℃, single yarn fineness 4.4 decitex, hot water shrinkage 1.8%
The polylactic acid stereocomplex fiber of was obtained.

The obtained polylactic acid stereocomplex fiber was passed through a carding machine and laminated with a cross lapper to obtain a web having a basis weight of 120 g / m ² . Further, this web was subjected to needling processing at a punch density of 192 punches / cm ² to obtain a nonwoven fabric of Example 6 having a thickness of 2 mm.

When the obtained non-woven fabric was cut into 30 cm × 30 cm and ironed with an iron set to a surface temperature of 170 ° C., the ironing property was A and the texture was good.

Example 7 In Example 6, polylactic acid containing L-lactic acid as a main component (L-lactic acid
-Lactic acid unit: 95.5 mol%, D-lactic acid unit: 4.5 mol%, melting point 154 ° C, relative viscosity: 1.827), and polylactic acid mainly composed of D-lactic acid (L-lactic acid) Unit: 6 mol%, D-lactic acid unit: 94 mol%, melting point 151
A polylactic acid stereocomplex fiber was prepared in the same manner as in Example 6 except that an equal mass of a chip composed of ° C and relative viscosity of 1.873) was mixed.

The polylactic acid stereocomplex fiber thus obtained had a high temperature crystal melting phase ratio of 92%, a melting start temperature of the high temperature crystal melting phase of 196 ° C., a melting point of 205 ° C., and a single yarn fineness of 4.
It was 4 decitex and the hot water shrinkage rate was 2.6%.

When a nonwoven fabric was prepared in the same manner as in Example 6 and the obtained nonwoven fabric was ironed in the same manner as in Example 6, the ironing property was A and the texture was good.

Example 8 Example 6 was carried out in the same manner as in Example 6 except that the web had a basis weight of 50 g / m 2 and was embossed at 200 ° C. without needling.

When the obtained non-woven fabric was ironed in the same manner as in Example 6, the ironing property was A and the texture after ironing was good.

[0058]

INDUSTRIAL APPLICABILITY The polylactic acid stereocomplex fiber of the present invention is one in which the polymer constituting the fiber has a high abundance ratio of the high temperature crystalline melting phase and the melting start temperature of the high temperature crystalline melting phase is 190 ° C. or higher. In addition, since the hot water shrinkage rate is 10% or less, when ironing a textile product made of this fiber, it is not necessary to pay close attention to the set temperature of the iron and the ironing method. Temperature 180
The texture does not harden even when ironed at ℃.

Further, it is possible to favorably perform heat treatment in the manufacturing and processing steps of a textile product such as a woven or knitted fabric or a nonwoven fabric made of this fiber.

Further, since it has the above-mentioned thermal characteristics, it can be satisfactorily obtained when a fiber product is obtained by mixing the polylactic acid stereocomplex fiber of the present invention with another natural fiber or synthetic fiber. A heat treatment can be applied in a processing step, and the obtained textile product can be ironed well at 180 ° C.

Therefore, since careful attention is not paid to heat, the polylactic acid stereocomplex fiber of the present invention can be used in various fields, and in the field of non-woven fabric which is an example of a fiber product, Interlining material for ironing, filter for filtering hot medium,
Shoulder pads for high-temperature washing and drying, cotton cots and beds for furniture, mattresses, cushions, mats, cushioning materials such as cushions for automobiles and vehicle seats that heat up under hot weather or around the engine when running, ceiling materials, panel materials, It can be used favorably as a sound-absorbing material and a vibration-proof material.

[Brief description of drawings]

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

[Explanation of symbols]

a: melting endotherm curve X: Low temperature crystal melting phase Y: High temperature crystal melting phase

Continued front page    F term (reference) 4L035 AA02 AA05 BB33 BB40 BB89                       BB90 BB91 CC03 CC20 DD19                       EE01 FF01 FF05 HH01 HH10                 4L047 AA21 AB10 BA03 CB05 CB10                       CC02 CC07 CC09 CC12                 4L048 AA20 AA42 AA44 AA48 AC14                       CA06                 4L055 AF33 AF44 AF47 EA01 EA20                       EA32 FA19 GA23 GA39

Claims (3)

[Claims] 1. A fiber comprising a polylactic acid-based polymer, wherein the polymer forms a stereo complex, and the high temperature crystalline melting phase of the polymer occupies 90% or more of the entire crystalline phase, and has a high temperature. The melting onset temperature of the crystalline melting phase is 190
A polylactic acid stereocomplex fiber having excellent heat resistance, which has a hot water shrinkage of 10% or less and a temperature of not less than 0 ° C. 2. A polylactic acid-based polymer is composed of poly-L-lactic acid containing L-lactic acid as a main component and poly-D-lactic acid containing D-lactic acid as a main component. The polylactic acid stereocomplex fiber according to claim 1. 3. A fiber product comprising the polylactic acid stereocomplex fiber according to claim 1 or 2.