JP3694103B2 - Naturally degradable composite fiber and its application products - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel splittable composite fiber capable of producing fibers and fiber structures that are naturally degradable and have excellent flexibility and a large specific surface area, and an application product thereof.
[0002]
[Prior art]
Conventional synthetic fiber made of synthetic resin has a slow degradation rate in the natural environment, generates a large amount of heat during incineration, damages the furnace, and increases carbon dioxide in the air. is necessary. For this reason, naturally degradable fibers made of aliphatic polyester are being developed, and contribution to environmental protection is expected. Some aliphatic polyesters have excellent fiber performance and are expected as new characteristic fiber materials, but fibers and fibers with various functions based on higher flexibility, special cross-sectional shape and large specific surface area. A product is desired. In response to such demands, conventional synthetic fibers are divided into split-type composite fibers, and are knitted fabrics, nonwoven fabrics, artificial leather, artificial suedes, high-performance wiping cloths, high-performance filters that excel in flexibility and gloss. Have been developed and widely used. However, split-type composite fibers have not been proposed yet in the field of fibers that decompose in a natural environment. The reason is that a combination of spinning materials (polymers) suitable for division and a division method are not yet known.
[0003]
[Problems to be solved by the invention]
An object of the present invention is a novel composite fiber that is naturally degradable, has an improved splitting ability, can produce fibers and fiber structures having excellent flexibility and a large specific surface area, and applications thereof In providing products. The present inventors have intensively studied the degradation of biodegradable polymers by chemical treatment, and found the fiber of the present invention that can be divided by chemical treatment.
[0004]
[Means for Solving the Problems]
The purpose is as follows: (1) a crystalline polymer [A] of an aliphatic polyester having a melting point of 140 ° C. or higher and “ an organic compound having a sulfone group and an organic compound having a sulfate group ” with respect to the aliphatic polyester. A composition [B] in which at least one selected compound is mixed in an amount of 1 to 50% by weight is composited in a single fiber, and (2) the composition [B] is a polymer in a cross section. This is achieved by the composite fiber of the present invention, characterized in that [A] is separated into at least two parts.
[0005]
Here, the aliphatic polyester includes (1) a hydroxyalkyl carboxylic acid such as glycolic acid, lactic acid, and hydroxybutyl carboxylic acid, (2) an aliphatic lactone such as glycolide, lactide, butyrolactone, and caprolactone, (3 ) Aliphatic diols such as ethylene glycol, propylene glycol, butanediol, hexanediol, etc. (4) Polyalkylene glycols such as polyethylene glycol, polypropylene recall, polybutylene ether, copolymers thereof, (5) Diethylene glycol , Oligomers of polyalkylene ethers such as triethylene glycol, ethylene / propylene glycol, bishydroxyethoxybutane, (6) polypropylene carbonate, polybutylene carbonate , Polyalkylene carbonate glycols such as polyhexane carbonate, polyoctane carbonate, polydecane carbonate and their oligomers, (7) aliphatic such as succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid A component derived from an aliphatic polyester polymerization raw material such as dicarboxylic acid as a main component, that is, 50% by weight or more (especially 60% or more), which is a homopolymer of aliphatic polyester, a block or / and random of aliphatic polyester 50% by weight or less (block or / and lander) of other components such as aromatic polyester, polyether, polycarbonate, polyamide, polyurea, polyurethane, polyorganosiloxane, etc. in the copolymerized polymer and aliphatic polyester ) Includes all copolymerized ones and / or mixed ones.
[0006]
The purpose of modifying aliphatic polyesters by copolymerization and mixing is to reduce crystallinity, lower melting point (reduction in polymerization temperature and molding temperature), improve melt flowability, impact resistance, and improve flexibility and elastic recovery. , Decrease or increase in heat resistance, glass transition temperature and heat shrinkability, friction coefficient, dyeability, improvement in hydrophilicity and water repellency, improvement in adhesion with other components, improvement or suppression of decomposability, and the like.
[0007]
In the composite fiber of the present invention, a crystalline polymer [A] of an aliphatic polyester having a melting point of 140 ° C. or higher and an aliphatic polyester composition [B] in which a specific component is mixed are combined (bonded). . Since the composition [B] is more decomposable by an aqueous alkaline solution than the polymer [A], the fiber of the present invention is easily divided by the aqueous alkaline treatment.
[0008]
The polymer [A] has a relatively small decomposability with an alkaline aqueous solution, and specific examples of preferable ones include poly L-lactic acid (melting point 175 ° C.), poly D-lactic acid (175 ° C.), poly 3-hydroxybutyrate (the same 180 ° C.), polyglycols Lido (same 230 ° C.) homopolymer such, and they were mainly small amounts of other components copolymerized or / and mixed modified polyester and the like. In general, in block copolymerization, the crystallinity and melting point decrease slowly, and the ratio of copolymerization components is preferably 50% or less, particularly 1 to 40%, and in most cases 1 to 30%. And the change in the melting point is remarkable, and the ratio of the copolymer component is preferably 0.5 to 20%, particularly preferably 1 to 10%. Of course, changes in the melting point and crystallinity due to copolymerization vary greatly depending on the copolymerization component, so it is necessary to pay attention to the melting endotherm and melting point of the crystal due to DSC. Changes in melting point and crystallinity due to the mixing of other components also vary considerably depending on the mixing component and mixing ratio, but are often not as significant as random copolymerization.
[0009]
In order to suppress hydrolysis due to alkali, it is also preferable to introduce a water repellent component into the polymer [A] by mixing or copolymerization. Examples of the water repellent component include fatty acids having 10 or more carbon atoms, particularly 15 or more alkyl groups, aliphatic alcohols, esters, amides, waxes, polyethylene and derivatives thereof, polyorganosiloxanes (for example, polydimethylsiloxane) and the like. Derivatives and the like. The mixing ratio or copolymerization ratio (weight) is not particularly limited, but in most cases, a range of about 0.1 to 20%, particularly about 0.5 to 10% is preferably used. The molecular weight of the polymer [A] is not particularly limited, but is preferably 50,000 or more, particularly preferably in the range of 70,000 to 300,000, and most preferably in the range of 80,000 to 200,000.
[0010]
In the present invention, the melting point is about 10 mg of sample weight in nitrogen, heated at a rate of 10 ° C./min for a sample that has been sufficiently stretched or / and heat-treated and dried using a scanning differential calorimeter (hereinafter referred to as DSC). It is the endothermic peak value temperature due to melting of the polymer crystal when measured under conditions. FIG. 10 schematically shows a DSC curve. The figure shows an example of measurement of a quenched sample that is hardly crystallized, 4 shows the change in the baseline due to glass transition, 5 shows the exothermic peak of crystallization due to heating during measurement, and 6 shows the endothermic peak due to melting of the crystal. Show. In a sufficiently crystallized sample, the baseline change 4 and the exothermic peak 5 due to glass transition disappear and are hardly observed. The melting point is the temperature of the minimum value (center value) of the endothermic peak 6 due to melting of the crystal, and the total endothermic amount of the endothermic peak 6 (integral value, proportional to the area of the shaded portion in FIG. 7) is the endothermic amount at the time of melting. To do. The glass transition point is the central temperature of the baseline change 4, but the same applies to the peak value temperature of the main dispersion of mechanical loss in the measurement of viscoelasticity. The unit of endothermic amount is Joule / gram (hereinafter referred to as J / g). When there are a plurality of melting points in a mixture or a block copolymer, the highest melting point (in the present invention) is taken as the melting point. However, if the endothermic peak at the highest temperature is negligible, for example, less than 5 J / g, and if there is a main peak at a lower temperature, for example, 20 J / g or more, the substantial melting point (polymer Extremely softening and temperature at which flow begins) may be considered the main peak. The melting endotherm is the sum of all melting endothermic peaks.
[0011]
The polymer [A] is a component having high crystallinity and a low hydrolysis rate, but preferably has high heat resistance and low heat shrinkability. From the viewpoint of the strength and heat resistance of the product obtained from the fiber of the present invention, the melting point of the polymer [A] needs to be 140 ° C. or higher, preferably 150 ° C. or higher, particularly preferably 160 ° C. or higher, and 170 ° C. or higher. Most preferred. Similarly, from a practical standpoint, the endothermic amount when the polymer [A] is melted is preferably 20 J / g or more, particularly preferably 30 / g or more, and most preferably 40 J / g or more. In many cases, the melting endotherm of the homopolymer of the crystalline aliphatic polyester is about 50 J / g or more.
[0012]
The composition [B] is at least one selected from the group consisting of a crystalline or amorphous aliphatic polyester and a specific hydrophilic compound, ie, “ an organic compound having a sulfone group and an organic compound having a sulfate ester group”. It is a mixture of seed compounds. By this hydrophilic component, the composition [B] becomes extremely sensitive to water and an aqueous solution of an alkali metal (sodium, potassium, lithium, calcium, magnesium, etc.) compound, and is easily hydrolyzed. As a result, the composite fiber of the present invention Can be divided, or can be divided easily when other means such as mechanical means or chemical swelling method are used in combination. For this purpose, the decomposition rate of the composition [B] in a fibrous form in a weakly alkaline aqueous solution, for example, in an aqueous solution of 3% by weight of sodium carbonate (sodium carbonate) at 98 to 100 ° C., that is, the weight reduction rate per unit time. Of the polymer [A] . It is preferably 5 times or more, particularly preferably 2 times or more, particularly preferably 5 times or more, most preferably 10 times or more, and usually a range of about 5 to 200 times is widely used .
Most preferably, the hydrophilic compound to be mixed with the composition [B] can be melt-mixed with the aliphatic polyester, and the composition [B] can be melt compound-spun.
[0014]
Examples of the organic compound having a sulfone group and the organic compound having a sulfate ester group, which are hydrophilic compounds mixed in the composition [B], include vinyl sulfonic acid, sulfonated styrene (sodium salt), and sodium methallyl sulfonate. , Thermoplastic polymers obtained by polymerizing or copolymerizing vinyl monomers having a sulfone group (sodium salt, etc.) such as 2-acrylamido-2-methylpropane sulfonic acid soda, alkylbenzene sulfonate soda, sulfate esters of various higher alcohols (sodium salt), etc. These surfactants may be mentioned. Incidentally, these sulfone compounds and sulfates, it is when the thermoplastic is not necessarily high, and mixed with a polyether such as a non-ionic surfactant or polyethylene glycol, that excellent melt fluidity can be obtained Many. In particular, sulfone compounds have the highest practicality because they are excellent in heat resistance.
[0016]
The mixing ratio of the hydrophilic compound to be mixed in the set Narubutsu [B] is in the range of 1 to 50 wt%, often is suitable in the range of about 3 to 30 wt%, 5-20 wt % Range is most widely used.
[0017]
The main component (50% or more) of the composition [B] is an aliphatic polyester, which is easily hydrolyzed with an alkali. For that purpose, those having low crystallinity, for example, those having an endothermic amount of 30 J / g or less, particularly 20 J / g or less, are preferable. Similarly, the aliphatic polyester forming the composition [B] preferably has a melting point of 120 ° C. or less, particularly preferably 100 ° C. or less, and similarly, an aliphatic polyester component having a melting point of 120 ° C. or less, particularly 100 ° C. or less, of 10% by weight or more, It is also preferable that 20% or more is copolymerized or / and mixed. Similarly, the glass transition point of the aliphatic polyester is preferably 30 ° C. or lower, and particularly preferably 0 ° C. or lower. An aliphatic polyester having a low melting point and glass transition point has a high decomposition rate in an alkaline aqueous solution at 100 ° C. or lower.
[0018]
The molecular weight of the composition [B] is not particularly limited, but in order to perform melt composite spinning with the polymer [A], it is desirable that the melt viscosity is approximately equal to or close to that of the polymer [A]. The overall weight average molecular weight is preferably close to that of the polymer [A]. That is, the average molecular weight of the composition [B] is preferably 50,000 or more, particularly preferably 70,000 to 300,000, and most preferably in the range of 80,000 to 200,000.
[0019]
Composition [B] is obtained by mixing the aliphatic polyester and the hydrophilic compound. Although the mixing method is not particularly limited, for example, both pellets and powder may be mixed at a predetermined ratio and melt-mixed with a screw extruder, a twin-screw extrusion kneader, or the like. Similarly, both melted separately may be mixed with a mechanical stirring device or may be mixed with a static mixer. The static mixer repeats the division and merging of the polymer flow by a flow guide device, and may be used in combination with a mechanical stirring device. Moreover, when there is no hindrance to the polymerization of the aliphatic polyester, it may be mixed in the polymerization step. In many cases, the composition [B] is completely decomposed and removed in the processing step and does not remain in the final product. Therefore, the coloration and dyeing fastness are not often a problem. However, the hydrolysis product is preferably completely decomposed, for example, by an activated sludge process. It is easy to select a biodegradable substance as the hydrophilic compound.
[0020]
In the cross section of the composite fiber of the present invention, it is necessary that the composition [B] separates the polymer [A] into at least two parts (hereinafter sometimes referred to as layers). With this composite structure, when the composition [B] is decomposed and removed, the fiber of the present invention can be divided into a plurality of fibers, and a fiber with a small fineness and a special cross section can be obtained. As the number of layers of the polymer [A] in the single fiber increases, a thin fiber having a large specific surface area can be obtained. The number of divisions needs to be 2 or more, and about 3 to 50, especially about 4 to 30 is most widely used. Those having a division number of about 3 to 10 are suitable for dresses, blouses, women's underwear, etc., and those having 4 to 30 are ultra-fine fibers such as ultra-high density knitted fabric, nonwoven fabric, artificial suede, artificial leather, filter, Suitable for wiping cloth and the like.
[0021]
The cross section of the fiber of the present invention can be arbitrarily selected from a circular shape, an oval shape, a flat shape, a gourd shape, a polygonal shape, a multi-leaf shape, and other various non-circular shapes (an irregular shape) and a hollow shape. Similarly, the single yarn fineness (before division) is also arbitrarily selected according to the purpose of use, but usually 0.5 to 50 denier, particularly 1 to 30 denier is preferably used, and 1.5 to 20 denier. Is the most widely used.
[0022]
The fiber of the present invention can be produced by complex-spinning the polymer [A] and the composition [B] by melt, wet, dry, dry-wet or other methods. In particular, melt spinning is preferable because of its high efficiency. For example, melt spinning can be performed at a low speed of a winding speed of 500 to 2000 m / min, a high speed spinning of a winding speed of 2000 to 5000 m / min, or an ultra-high speed spinning of a winding speed of 5000 m / min or more. Or heat treatment. In general, stretching is performed about 3 to 6 times for low speed spinning and about 1.5 to 2.5 times for high speed spinning, and stretching is unnecessary or about 2 times or less for ultra high speed spinning. A so-called spin draw method in which spinning and drawing are continuously performed can also be preferably applied.
[0023]
Similarly, a method such as a melt blow method, a flash spinning method, or a spun bond method in which the polymer [A] and the composition [B] are combined and spun from an orifice and simultaneously made into a nonwoven fabric can be applied.
[0024]
The composite fiber of the present invention can be in any form depending on the purpose of use, such as continuous filament, monofilament, multifilament, cut staple, spun yarn and the like. Among the composite fibers of the present invention, those having a composite structure other than the core-sheath type or sea-island type and having a particularly weak silicon mutual component and weakened mutual adhesiveness between components may show peeling or cracking only by stretching. is there. Peeling and splitting further proceeds by heating, swelling, alkali treatment, and the like. The alkali treatment can be performed with an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate or other alkaline compounds at room temperature or under heating. The type, concentration, pH, treatment time and the like of the alkali compound are arbitrary, but PH of 7.5 or more, particularly 8 or more are often preferable. However, since the polymer [A] is also decomposed when the pH is too high, it is preferable to select conditions under which the polymer [A] is not significantly decomposed or damaged.
[0025]
On the other hand, when the decomposability and releasability are weak, a mechanical method such as false twisting, kneading, and tapping may be applied as necessary in addition to heating and swelling. That is, the composite fiber of the present invention can be applied to division by other chemical methods or mechanical methods in addition to division by alkali treatment. The peeling method using a mechanical method or the like has an advantage that the weight loss is small as compared with a method in which the composition [B] is hydrolyzed and completely removed by alkali and divided. In general, during fiber production or processing into a knitted fabric, it is often preferable that separation or division is suppressed to a latent level, and after making into a knitted fabric or the like, complete separation and division, for example, in a dyeing finishing process is often performed. This is because ultrafine fibers and ultrafine fibers are easy to cut due to friction in manufacturing and processing steps and often cause trouble.
[0026]
The composite fiber of the present invention includes various pigments, dyes, colorants, water repellents, water absorbents, flame retardants, stabilizers, antioxidants, ultraviolet absorbers, metal particles, inorganic compound particles, crystal nucleating agents, lubricants, plastics. Agents, antibacterial agents, fragrances and other additives can be mixed.
[0027]
The fibers of the present invention can be used alone or in combination with other fibers to produce yarns, strings, ropes, knitted fabrics, woven fabrics, non-woven fabrics, paper, composite materials and other structures. When mixed with other fibers, it is particularly preferable to use a mixture with natural organic fibers such as cotton, wool and silk, and natural degradable fibers such as aliphatic polyester fibers, since a completely natural degradable product can be obtained.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
The cross section of the composite fiber which is an Example of this invention to FIGS. 1-9 is shown. In the figure, 1 indicates a polymer [A], 2 indicates a composition [B], and 3 indicates a hollow portion. FIG. 1 is an example of a three-layer parallel type and a two-divided type. The parallel type refers to a structure in which both components are arranged alternately. FIG. 2 is an example in which the polymer [A] is divided into four layers by the layer of the radial composition [B]. The radial type means that one component, for example, the composition [B] is in a radial form. 3 is a 9-layer radial type, FIG. 4 is a 9-layer multiple parallel type, FIG. 5 is a combination of a parallel type and a radial type, FIG. 6 is a core-sheath type with 7 cores, and FIG. Is an island type in which the islands are dispersed in the sea, FIG. 8 is an example of a non-circular radiation type, and FIG. 9 is an example of a hollow radiation type. In addition to FIGS. 1-9, a wide variety of combinations are possible according to the present invention. In addition to the polymer [A] and the composition [B], a third component can be combined. For example, a third polymer may be disposed in place of the hollow portion in FIG.
[0029]
The composite ratio (cross-sectional area ratio) between the polymer [A] and the composition [B] is not particularly limited, and may be arbitrarily selected according to the purpose. In many cases, the composite ratio is preferably in the range of 20/1 to 1/2, and the range of 10/1 to 1/1 is widely used. That is, it is often preferable that the ratio of the polymer [A] is larger than that of the composition [B] because the weight loss due to alkali hydrolysis is small.
[0030]
【Example】
In the following examples,% and parts are by weight unless otherwise specified. The molecular weight of the aliphatic polyester is a weight average value of dispersion of polymer components excluding components having a molecular weight of 1000 or less in GPC analysis of a 0.1% chloroform solution of a sample.
[0031]
Example 1
3 parts of polyethylene glycol (PEG) having a molecular weight of 8000 and hydroxyl groups at both ends, 98 parts of L-lactide, 100 ppm of tin octylate, and 0.1 part of Ciba Geigy's antioxidant Irganox 1010 were mixed, and 188 ° C. in a nitrogen atmosphere. For 12 minutes in a twin-screw extruder and finally 0.1% of silicon oil (dimethylsiloxane) was mixed, extruded from the die, formed into a cooling chip, and treated in a nitrogen atmosphere at 140 ° C. for 4 hours ( (Solid phase polymerization), washed with acetone containing 0.1% hydrochloric acid, and then washed 5 times with acetone and dried to obtain a block copolymer BP1 of polylactic acid (PLA) and PEG. Polymer BP1 has a molecular weight of 122,000, a PEG component content of about 3%, a melting point of 174 ° C., and a melting endotherm of 55 J / g when fully oriented and crystallized. However, it is excellent in melt fluidity and stretchability, and melt compound spinning is easy.
[0032]
Random copolymer of polybutylene succinate (PBS) and polybutylene adipate (PBA) in a molar ratio of 4/1. Both ends are hydroxyl groups and have a molecular weight of 125,000, a melting point of 93 ° C., 80 parts, and a molecular weight of 20000. 5 parts of PEG, 20 parts of L-lactide, 30 ppm of tin octylate and 0.1 part of the above irganox were mixed, and then polymerized in the same manner as the polymer P1 to form a block copolymer of the PBS / PBA copolymer and polylactic acid. MP1 having a melting point of 90 ° C. was obtained from a mixed composition of a polymer (PBS / PBA / PLA) and a block copolymer of polylactic acid and polyethylene glycol (PLA / PEG). Assuming that the reactivity of each hydroxyl group is equal and all lactide has reacted, the PLA component in the PBS / PBA / PLA block copolymer is about 18%, the molecular weight is about 150,000, and the PLA / PEG block copolymer. The PLA component is estimated to be about 52%, and the molecular weight is estimated to be about 40,000. Both polymers have a common component called PLA, so the affinity is quite high and they are uniformly mixed.
[0033]
A PEG / PLA block copolymer obtained by mixing 20 parts of L-lactide, 20 parts of the above-mentioned Irganox, and 20 ppm of tin octylate with 80 parts of PEG having a molecular weight of 20000 is a PEG / PLA block copolymer obtained by reacting at 180 ° C. for 30 minutes. Is BP2. 50 parts of PEG having a molecular weight of 20,000, 50 parts of sodium dodecylbenzenesulfonate and 0.3 part of the above irganox were mixed and stirred at 180 ° C. under a pressure of 1 Torr for 1 hour to completely dehydrate 1 part and 4 parts of BP2. MP3 is melt-mixed at 180 ° C. MP4 is obtained by melt-mixing MP3 and MP1 at a ratio of 7/93 at 220 ° C.
[0034]
BP1 and MP4 are melted separately at 220 ° C. and sent to a composite spinneret while being metered by a gear pump. BP1 is component 1, MP4 is component 2, and a composite ratio (volume ratio) of 4/1 is shown in FIG. It is compounded radially and spun from an orifice with a diameter of 0.25 mm at 220 ° C., cooled in air, wound at a speed of 1500 m / min while being oiled, stretched 3.9 times at 80 ° C., and then tensioned Under heat treatment at 100 ° C., a drawn yarn F1 having a 75 denier / 25 filament was obtained. For comparison, similar to the drawn yarn F1, except that a composite fiber obtained by using BP1 not mixed with a silicon compound as a component 1 and a polybutylene succinate having a melting point of 116 ° C. and a molecular weight of 125,000 as a component 2 is drawn. The yarn is F2 (comparative example).
[0035]
A circular knitted fabric is produced using the drawn yarn F1, and it is put into a 3% aqueous solution of sodium carbonate at 98 ° C., treated for 10 minutes, taken out, dried, and contacted with a rotating roll wound with sandpaper, and a raised knitted fabric K1 was obtained. The napped fibers in the knitted fabric K1 obtained from the fibers of the present invention were almost divided, and the knitted fabric had a very soft touch. Similarly, the raised fibers in the raised knitted fabric K2 obtained by boiling, drying and raising the knitted fabric obtained from the drawn yarn F2 of the comparative example are hardly divided, and the knitted fabric K2 has a hard touch. .
[0036]
Example 2
Instead of the PBS / PBA random copolymer (melting point: 93 ° C.) of Example 1, polybutylene succinate (homopolymer) having a melting point of 116 ° C. and a molecular weight of 125,000 was used. In the same manner as above, a drawn yarn F3 was obtained, and the circular knitted fabric obtained therefrom was treated in the same manner as the raised knitted fabric K1 of Example 1 to obtain a raised knitted fabric K3. The raised knitted fabric K3 was excellent in flexibility because the nappings were completely divided like the raised knitted fabric K1.
[0037]
【The invention's effect】
According to the present invention, composite fibers that can be decomposed in a natural environment and can be easily divided by treatment with an alkaline aqueous solution have been obtained for the first time. The fibers of the present invention can be used to produce extremely soft and high-performance knitted fabrics, nonwoven fabrics, artificial suedes, artificial leather, and other fiber structures. It can be applied to fields such as high-performance filters, water-absorbing materials, oil-absorbing materials, etc., taking advantage of its features and characteristics. In particular, it is extremely useful for items that are disposable in fields such as agriculture, horticulture, civil engineering, fisheries, machinery industry, packaging, household goods, and other applications that require natural degradability, and is expected to contribute greatly to environmental protection. .
[Brief description of the drawings]
FIG. 1 is a cross section of a three-layer parallel type composite fiber according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a four-layer radiation type composite fiber that is an example of the present invention.
FIG. 3 is a cross-sectional view of a nine-layer radiating conjugate fiber that is an example of the present invention.
FIG. 4 is a cross-sectional view of a 9-layer parallel type composite fiber that is an example of the present invention.
FIG. 5 is a cross-sectional view of a composite fiber in which a parallel type and a radial type according to an embodiment of the present invention are combined.
FIG. 6 is a cross section of a core-sheath type composite fiber having seven cores according to an embodiment of the present invention.
FIG. 7 is a cross section of a sea-island type composite fiber that is an example of the present invention.
FIG. 8 is a cross-sectional view of a non-circular radiating conjugate fiber that is an example of the present invention.
FIG. 9 is a cross-sectional view of a hollow radiation type composite fiber that is an example of the present invention.
FIG. 10 is an example of a DSC curve of an amorphous polymer by a scanning differential calorimeter.
[Explanation of symbols]
1 Polymer [A] 2 Composition [B] 3 Hollow portion 4 Baseline change due to glass transition 5 Exothermic peak due to crystallization 6 Endothermic peak due to melting of crystal

Claims (4)

(1) At least selected from the group consisting of a crystalline polymer [A] of an aliphatic polyester having a melting point of 140 ° C. or higher and “ an organic compound having a sulfone group and an organic compound having a sulfate group ” with respect to the aliphatic polyester. The composition [B] in which 1 to 50% by weight of one compound is mixed is combined in a single fiber, and (2) the composition [B] is a polymer [A] in a cross section. A composite fiber characterized by being separated into at least two parts.   The polymer [A] is selected from the group of “poly L-lactic acid, poly D-lactic acid, poly 3-hydroxybutyrate, polyglycolide, and modified polyester containing them as a main component”, and the composition [ 2. The composite fiber according to claim 1, wherein the aliphatic polyester constituting B] contains 10% by weight or more of a component having a melting point or a softening point of 120 ° C. or less.   The composite fiber according to claim 1, wherein the composite structure is selected from the group of “radiation type, parallel type, multi-core type, sea-island type, and combinations thereof”.   A fiber and a fiber structure in which the conjugate fiber according to claim 1 is used at least in part, and the conjugate fiber is at least partially divided.

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