JP3694101B2 - 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 fibers made of synthetic resin have a slow degradation rate in the natural environment and generate a large amount of heat during incineration, and therefore need to be reviewed from the standpoint of protecting the natural environment. 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.
[0004]
[Means for Solving the Problems]
The object of the present invention is achieved by an aliphatic polyester composite fiber that satisfies all of the following items (1), (2), (3), and (4), and an application product thereof.
(1) A crystalline polymer [1] of an aliphatic polyester having a melting point of 140 ° C. or higher, a crystalline segment (H) of an aliphatic polyester having a melting point of 140 ° C. or higher, a melting point of 120 ° C. or lower, and a glass transition point of 30 ° C. or lower. The block copolymer [2] to which the aliphatic polyester segment (S) is bonded is combined in a single fiber.
(2) One or both of the polymer [1] and the polymer [2] contain 0.05% by weight or more of the polyorganosiloxane component.
(3) In the cross section, the polymer [2] separates the polymer [1] into at least two parts.
(4) Both the polymer [1] and the polymer [2] occupy a part of the surface of the fiber.
[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 [1] of an aliphatic polyester having a melting point of 140 ° C. or higher and an aliphatic polyester block copolymer [2] having a specific structure are combined (bonded). Here, the segment is a part of the polymer molecular chain and may be called a block.
[0008]
Specific examples of preferable polymer [1] include poly L-lactic acid (melting point 175 ° C.), poly D-lactic acid (175 ° C.), polyhydroxybutyrate (180 ° C.), polyglycolic acid (230 ° C.). ), And those obtained by copolymerizing or / and mixing small amounts of other components. In general, changes in crystallinity and melting point are slow in block copolymerization, 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]
The molecular weight of the polymer [1] is not particularly limited, but in many cases, it 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. Here, the melting point was determined by using a scanning differential calorimeter (hereinafter referred to as “DSC”) for a sample that was sufficiently stretched and / or heat-treated and dried, and a sample weight of about 10 mg, in nitrogen, at a heating rate of 10 ° C./min. The endothermic peak value temperature due to melting of the polymer crystal as measured by. 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. In the present invention, the temperature of the minimum value (center value) of the endothermic peak 6 due to melting of the crystal is taken as the melting point, and the total endothermic amount of the endothermic peak 6 (integral value, proportional to the area of the hatched portion in FIG. 10) The endothermic amount. 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.
[0010]
The polymer [1] is a component having high crystallinity and low heat shrinkability. Suitable for the polymer [1] include the crystalline homopolymer and a small amount (for example, 30% or less, particularly 20% or less) of the second component or the third component to such an extent that the crystallinity is not significantly impaired. The thing which copolymerized or / and mixed the component is mentioned. From the viewpoint of the strength and heat resistance of the product obtained from the fiber of the present invention, the endothermic amount when the polymer [1] is melted needs to be 20 J / g or more, particularly preferably 30 / g or more, and more than 40 J / g. Is most preferred. In many cases, the melting endotherm of the homopolymer of the crystalline aliphatic polyester is about 50 J / g or more. Similarly, from a practical standpoint, the melting point of the polymer [1] needs to be 140 ° C. or higher, preferably 150 ° C. or higher, particularly preferably 160 ° C. or higher, and most preferably 170 ° C. or higher.
[0011]
Polymer [2] is composed of an aliphatic polyester crystalline segment having a melting point of 140 ° C. or higher (H, hereinafter sometimes referred to as a hard segment) and an aliphatic polyester segment having a melting point of 120 ° C. or lower and a glass transition point of 30 ° C. or lower. (S, hereinafter may be referred to as a soft segment) is a block copolymer to which the polymer [1] and the polymer [2] are easily separated. However, the divided fibers become thinner. For high shrinkage, the hard segment is preferably strong and its melting point needs to be 140 ° C. or higher, preferably 150 ° C. or higher, particularly preferably 160 ° C. or higher, and most preferably 170 ° C. or higher. On the other hand, the softer the softer the softer the segment, the greater the thermal shrinkage. In the case of crystallinity, the melting point needs to be 120 ° C or lower, preferably 100 ° C or lower, particularly preferably 90 ° C or lower, 80 or lower or non-crystalline (non-crystalline) Crystallinity) is the most preferred. For example, when treated with water at 100 ° C., the polymer [2] contracts strongly if the melting point of the soft segment is 100 ° C. or less. However, the melting point of the hard segment is 140 ° C. or higher, and the polymer [2] shrinks but does not melt. Similarly, in order to realize large shrinkage, the glass transition point of the soft segment is preferably 20 ° C. or less, particularly preferably 0 ° C. or less. When the soft segment of the polymer [2] is completely amorphous, the melting point is the same as the glass transition point. Examples of polyesters particularly suitable for the soft segment of the polymer [2] and having a melting point of 120 ° C. or lower and a glass transition point of 0 ° C. or lower include polyethylene succinate, polyethylene adipate, polyethylene sebacate, polycaprolactone, Polyethylene azelate, polyethylene decanate, polypropylene succinate, polypropylene adipate, polypropylene sebacate, polypropylene azelate, polypropylene decanate, polybutylene succinate, polybutylene adipate, polybutylene sebacate, polybutylene azelate, poly 2 to 2 carbon atoms such as butylene decanate, polyhexane succinate, polyhexane adipate, polyhexane sebacate, polyhexane azelate, polyhexane ndecanate And polyalkylene alkylates and their components (random and block) copolymer having a linear or a branched alkyl group of degree. In addition, a polyester ether in which an oligomer of a polyalkylene glycol such as diethylene glycol, triethylene glycol, or ethylene / propylene glycol and an aliphatic dicarboxylic acid is combined is also preferable as the soft segment.
[0012]
In general, homopolymers are often crystalline, but the soft segment (S) of the block copolymer [2] may be reduced in crystallinity or become amorphous by copolymerization of two or more of them. I can do it. Although the molecular weight of a soft segment is not specifically limited, For example, 1000-150,000, especially 2000-100,000 are preferable, and 5000-50,000 are the most preferable. In order to further soften the soft segment, a plasticizer or the like may be added.
[0013]
The hard segment (H) of the polymer [2] is a high-melting crystalline segment. Examples of such a high melting point aliphatic polyester are as described above. To strengthen this type of hard segment, it is necessary to have high crystallinity. To maintain crystallinity, homopolymers are the most preferable, and the amount of the second component is suppressed even in the case of modification by copolymerization or mixing. For example, the amount of the second component is preferably 20% or less, particularly preferably 10% or less, and most preferably 5% or less. The molecular weight of the hard segment is not particularly limited, but is preferably 5000 to 200,000, particularly preferably 8000 to 100,000, and most preferably 10,000 to 50,000.
[0014]
The hard segment (H) and soft segment (S) of the polymer [2] are combined to form a block copolymer. The bonding method is not particularly limited and may be a normal chemical bond. For example, an ester bond, an amide bond, a urethane bond, a urea bond, or the like may be used. For example, a hard segment may be formed by reacting (polymerizing) lactide or glycoride to a low melting point aliphatic polyester for soft segment having a hydroxyl group at the terminal. In addition, both a soft segment polyester having a hydroxyl group at the terminal and a hard segment polyester may be reacted with a dicarboxylic acid anhydride or a halide to succeed. In these cases, the seam is an ester bond. It is also possible to react diisocyanate with the terminal hydroxyl group and connect it with a urethane bond. The weight ratio of the hard segment (H) and the soft segment (S) of the polymer [2] is not particularly limited because it differs depending on each component, but the fiber strength, elastic modulus, heat resistance, heat shrinkability, etc. are preferable. In order to obtain a range, this ratio is preferably in the range of 2/8 to 8/2, more preferably in the range of 3/7 to 7/3, and most preferably in the range of 4/6 to 6/4. The harder the hard segment and the softer the soft segment, the more effective each is.
[0015]
The molecular weight of the polymer [2] is not particularly limited, but in many cases is preferably 50,000 or more, particularly preferably 70,000 to 300,000, and most preferably in the range of 80 to 200,000.
[0016]
The first factor that the composite fiber of the present invention can be divided (peeled) relatively easily is that the difference between the heat shrinkage force and / or the shrinkage rate of the polymer [1] and the polymer [2] is large. It is. The shrinkage ratio of the polymer [1] with boiling water is preferably 20% or less, particularly preferably 15% or less, and most preferably 10% or less. Similarly, the shrinkage of the polymer [2] is preferably 20% or more, particularly preferably 30% or more, and most preferably 40% or more. The difference in shrinkage between the polymer [1] and the polymer [2] is preferably 10% or more, particularly preferably 20% or more, and most preferably 30% or more. In general, the more soft segments (low melting point components) in the polymer [2], the greater the shrinkage. According to the explanation so far, the polymer [1] and the polymer [2] can be selected to easily realize a sufficient difference in shrinkage.
[0017]
The second factor that the composite fiber of the present invention can be divided relatively easily is that one or both of the polymer [1] and the polymer [2] contains a polyorganosiloxane component, and therefore the mutual adhesiveness is low. It is. The polyorganosiloxane has a side chain of an alkyl group or / and an aryl group, and examples thereof include polydimethylsiloxane, polymethylethylsiloxane, polydiethylsiloxane, polymethylphenylsiloxane, and polydiphenylsiloxane. Is most preferred. The more the polyorganosiloxane component in the polymer, the lower the adhesion between the polymer [1] and the polymer [2] and the easier the peeling. The content of at least one polyorganosiloxane component of both polymers must be 0.05% by weight or more, preferably 0.1% or more, particularly preferably in the range of 0.3 to 8%, 0.5% A range of ˜5% is most widely used. In particular, the polyorganosiloxane component is preferably contained in the polymer [2] in a larger amount than the polymer [1] or is used only in the polymer [2]. Methods for incorporating the polyorganosiloxane into the polymer [1] or / and the polymer [2] include a copolymerization method and a mixing method. In the copolymerization method, polyorganosiloxane having a hydroxyl group at the terminal and an aliphatic polyester polymerization raw material such as lactide or glycolide may be reacted (polymerized), mixed with an aliphatic polyester having a hydroxyl group at the terminal, for example, dicarboxylic acid. An anhydride, dicarboxylic acid halide, diisocyanate and the like may be reacted to bond them together. For example, a prepolymer (having an isocyanate group) obtained by reacting an equimolar diisocyanate with a polysiloxane terminal hydroxyl group can be mixed and reacted with an aliphatic polyester having a hydroxyl group. However, the copolymerization method has a difficult problem that a very small amount of silicon compound is uniformly mixed and reacted with a large amount of aliphatic polyester.
[0018]
The mixing method is a method in which polyorganosiloxane is mixed with aliphatic polyester, but both have poor mutual affinity, and it is quite difficult to mix uniformly. One method of improving affinity is the application of surfactants. Another method is a method using a block copolymer of an aliphatic polyester and a polyorganosiloxane. The method for producing the block copolymer of the aliphatic polyester and the polyorganosiloxane is as described above, and it is relatively easy and most practical to mix the separately prepared block copolymer into the aliphatic polyester. is there. Producing this block copolymer separately is relatively easy because it requires a small amount and can be applied with special devices and methods such as powerful stirring devices, ultrasonic devices, surfactants and the like. In this case, the ratio of the polyorganosiloxane component in the block copolymer of aliphatic polyester and polyorganosiloxane is preferably 5 to 95%, particularly preferably 10 to 90%, and most preferably 20 to 80%. Used. This block copolymer can be used as a dispersant (surfactant) when polyorganosiloxane is dispersed (mixed) in an aliphatic polyester, has a wide range of applications, and is particularly useful in the present invention.
[0019]
In the fiber cross section of the present invention, the polymer [2] separates the polymer [1] into at least two parts (hereinafter sometimes referred to as layers), and both components occupy part of the fiber surface. Need to be. With this composite structure, the fiber of the present invention can be divided into a plurality of pieces, and a fiber having a special cross section with a small fineness can be obtained. As the number of layers of the polymer [1] in the single fiber increases, a finer fiber having a larger specific surface area can be obtained. The number of divisions needs to be 2 or more, and about 3 to 20 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 20 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.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
1 to 9 show a cross section of a composite fiber suitable for the present invention. In the figure, 1 is a polymer [1], 2 is a polymer [2], and 3 is a hollow part. FIG. 1 shows an example of a three-layer parallel type and a three-part split type. The parallel type refers to a structure in which both components are arranged alternately. FIG. 2 is an example in which the polymer [1] is divided into four layers by the layer of the radial polymer [2]. The radial type means that one component, for example, the polymer [2] is in a radial form. 3 is a nine-layer radiation type, FIG. 4 is a nine-layer multiple parallel type, FIG. 5 is a petal-like nine-layer radiation type, FIG. 6 is a combination of a radial type and a multiple parallel type, and FIG. 8 is an example of a modified multiple parallel 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 [1] and the polymer [2], a third component may be combined. For example, a third polymer may be disposed in place of the hollow portion in FIG. A composite structure in which one component occupies the entire surface of the fiber, such as a core-sheath type or a sea-island type, cannot be used in the present invention.
[0021]
The composite ratio (cross-sectional area ratio) between the polymer [1] and the polymer [2] 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 1/5, and the range of 10/1 to 1/2 is widely used. That is, those having a larger ratio of the low shrinkage component 1 than the high shrinkage component 2 are often suitable, and the composite ratio is most widely used in the range of 10/1 to 1/1.
[0022]
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.
[0023]
The fiber of the present invention can be produced by complex-spinning the polymer (1) and the polymer (2) 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.
[0024]
Similarly, methods such as a melt blow method, a flash spinning method, and a spun bond method in which the polymer (1) and the polymer (2) are combined and spun from an orifice and simultaneously made into a nonwoven fabric can be applied.
[0025]
The composite fiber of the present invention can be in any form such as continuous filament, monofilament, multifilament, cut staple and the like. Among the composite fibers of the present invention, those having a large silicon component and particularly weakened mutual adhesiveness between components may be peeled off or cracked only by stretching. If it heats or swells, peeling and division further progress. When the peelability is weak, a mechanical method such as false twisting, kneading, or hitting may be applied as necessary in addition to heating and swelling. Although a method of dissolving and removing the polymer [2] with a solvent can be applied, the peeling method is preferred because there is no weight loss. In general, during fiber production or processing into a knitted fabric, it is often preferable to suppress the peeling to a latent level, and after making into a knitted fabric or the like, completely peel and divide, for example, in a dyeing finishing process. This is because extra fine fibers and extra extra fine fibers are easily 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]
【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.
[0029]
[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 10 parts of Ciba Geigy's antioxidant Irganox 1010 were mixed in a nitrogen atmosphere at 188 °. Polymerized by stirring and stirring in a twin-screw extruder for 15 minutes at C, extruded from the die, formed into a cooling chip, treated in a nitrogen atmosphere at 140 ° C for 4 hours (solid-phase polymerization), and acetone containing 0.1% hydrochloric acid. Washing was followed by washing 5 times with acetone and then drying to obtain a block copolymer P1 of polylactic acid and PEG. Polymer P1 has a molecular weight of 148,000, a PEG component content of about 3%, a melting point of 174 ° C., a melting endotherm of 55 J / g when fully oriented and crystallized, and a melting point and crystallinity of polylactic acid homopolymer. Although it is almost the same as a polymer, it is excellent in melt fluidity and stretchability, is easy to perform melt composite spinning, and the shrinkage ratio of the drawn yarn with boiling water is often about 10 to 15%.
[0030]
Random copolymer of polybutylene succinate and polybutylene adipate having a molar ratio of 4/1, both ends having hydroxyl groups, molecular weight 125,000, melting point 93 ° C. 25 parts, L-lactide 76 parts, tin octylate 80 ppm was mixed and polymerized in the same manner as the polymer P1 to obtain a block copolymer P2 of about 3/1 of polylactic acid and polybutylene succinate / adipate. The polymer P2 has a molecular weight of 17,000, two melting endothermic peaks by DSC, and its melting point and melting endotherm are 168 ° C. (36 J / g) and 86 ° C. (6.5 J / g), respectively. Presumably corresponding to the polybutylene succinate / adipate copolymer segment, the melting point (typical) of this polymer is 168 ° C. In many cases, the shrinkage ratio of the drawn yarn obtained from the polymer P2 with boiling water is about 30 to 70%. 1 mol of octyl alcohol and 100 ppm of tin octylate are mixed with 1 mol of L-lactide and polymerized in the same manner as polymer P1, and polylactic acid having a hydroxyl group at one end and a molecular weight of 6700 is obtained as polymer P3. To do. After equimolar hexane diisocyanate is mixed and reacted with polymer P3 melted at 180 ° C., the resulting prepolymer having an isocyanate group at one end is mixed with a polydimethylsiloxane having a hydroxyl group at one end and a molecular weight of 5500, etc. The resulting mixture was melt mixed with a 180 ° C. twin screw extruder and then reacted for 30 minutes while passing through a static mixer having an element 120. A block copolymer of polylactic acid / polydimethylsiloxane = about 55/45 was obtained. The polymer is designated as polymer P4.
[0031]
While polymer P2 is melted and sent at 220 ° C., 3% of polymer P4 melted at 220 ° C. is mixed with it, and further mixed in a Kenix type static mixer with 60 elements, and then supplied to the composite spinneret by a metering pump. did. On the other hand, the polymer P1 is melted at 220 ° C. with a screw extruder and supplied to the composite spinneret with a metering pump, the polymer P1 is component 1, the polymer P2 / polymer P4 mixture is component 2, and the composite ratio is 4/1 (volume). 2), it is spun from an orifice having a diameter of 0.20 mm, wound in air, wound at a speed of 1500 m / min while being oiled, and stretched 3.9 times at 80 ° C. Subsequently, heat treatment was performed at 100 ° C. under tension, and a 75 denier / 25 filament drawn yarn F1 was obtained.
[0032]
For comparison, polymer P1 and polymer P2 are used (without using a silicon compound), and a composite fiber obtained in the same manner as the drawn yarn F1 is hereinafter referred to as drawn yarn F2 (comparative example). A circular knitted fabric was produced by using the drawn yarn F1, put into boiling water, boiled for 15 minutes, taken out, dried, and contacted with a rotating roll wound with sandpaper to obtain a raised knitted fabric K1. 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. .
[0033]
[Example 2]
Polylactic acid / polycaprolactone obtained by reacting 76 parts of L-lactide with 25 parts of polycaprolactone having a molecular weight of 128,000 and a melting point of 60 ° C. One block copolymer is designated P5. Polymer P5 has a molecular weight of 103,000, its melting point and melting endotherm by DSC are 166 ° C. (35 J / g) and 52 ° C. (6.6 J / g), and its melting point (representative value) is 166 ° C. In many cases, the contraction of the drawn yarn with boiling water is about 30 to 70%. Similar to the composite fiber F1 of Example 1, except that the composite fiber obtained by using the polymer P5 instead of the polymer P2 is F3. Raised knitted fabric K3 was obtained using composite fiber F3 in the same manner as raised knitted fabric K1 of Example 1 below. The brushed knitted fabric K3 according to the present invention was composed of fine fibers with split nappings and had a very soft feel.
[0034]
【The invention's effect】
According to the present invention, a composite fiber which can be decomposed in a natural environment and can be divided by heating or mechanical means has been obtained for the first time. From the fibers of the present invention, extremely soft and high-performance knitted fabrics, non-woven fabrics, artificial suedes, artificial leather and other fiber structures can be obtained. It can be applied to the field of materials (for example, high-performance filters, water-absorbing materials, oil-absorbing materials, etc.) taking advantage of its features and characteristics. In particular, it is expected to contribute greatly to environmental protection as it is extremely useful for items that are disposable in the fields of agriculture, horticulture, civil engineering, fisheries, machinery industry, packaging, household goods, and other applications that require natural decomposition. The
[Brief description of the drawings]
FIG. 1 is an example of a cross section of a three-layer parallel type composite fiber useful in the present invention.
FIG. 2 is an example of a cross section of a five-layer radial conjugate fiber useful in the present invention.
FIG. 3 is an example of a cross section of a nine-layer radial conjugate fiber useful in the present invention.
FIG. 4 is an example of a cross section of a 9-layer parallel composite fiber useful in the present invention.
FIG. 5 is an example of a cross section of a petal-like radial conjugate fiber useful in the present invention.
FIG. 6 is an example of a cross section of a composite fiber in which a parallel type and a radial type useful for the present invention are combined.
FIG. 7 is an example of a cross section of a non-circular radial conjugate fiber useful in the present invention.
FIG. 8 is an example of a cross section of a non-circular side-by-side composite fiber useful in the present invention.
FIG. 9 is an example of a cross section of a hollow radiating conjugate fiber useful in the present invention.
FIG. 10 is an example of a DSC curve of a crystalline polymer.
[Explanation of symbols]
1 Polymer [1] 2 Polymer [2] 3 Hollow portion 4 Baseline change due to glass transition 5 Exothermic peak due to crystallization 6 Endothermic peak due to melting

Claims (4)

An aliphatic polyester composite fiber satisfying all of the following items (1), (2), (3) and (4).
(1) A crystalline polymer [1] of an aliphatic polyester having a melting point of 140 ° C. or higher, a crystalline segment (H) of an aliphatic polyester having a melting point of 140 ° C. or higher, a melting point of 120 ° C. or lower, and a glass transition point of 30 ° C. or lower. The block copolymer [2] to which the aliphatic polyester segment (S) is bonded is combined in a single fiber.
(2) One or both of the polymer [1] and the polymer [2] contain 0.05% by weight or more of the polyorganosiloxane component.
(3) In the cross section, the polymer [2] separates the polymer [1] into at least two parts.
(4) Both the polymer [1] and the polymer [2] occupy a part of the surface of the fiber. The crystalline polymer [1] of the aliphatic polyester is selected from the group of “polylactic acid, poly-3-hydroxybutyrate, polyglycolide and modified polyester containing them as a main component”, and a polyorganosiloxane component The composite fiber according to claim 1, wherein is a polysiloxane having at least one group selected from the group of "alkyl group and aryl group". The composite fiber according to claim 1, wherein the composite structure is selected from the group of “radiation type, parallel type, and combinations thereof”. A fiber and a fiber structure, wherein the composite fiber according to claim 1 is used at least in part and the composite fiber is divided.

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