JPH09302530A - Naturally degradable composite fiber and its application products - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a dividable composite fiber capable of producing a knitted woven fabric, a non-woven fabric and other fiber structures which are naturally degradable and extremely soft and have excellent functions. And SOLUTION: The conjugate fiber of the present invention comprises a crystalline polymer 1 of an aliphatic polyester having a melting point of 140 ° C or higher, and a melting point of 140 ° C.
Crystalline segment and melting point 1 of the above aliphatic polyester
A block copolymer 2 having an aliphatic polyester segment having a glass transition point of 20 ° C. or lower and a glass transition point of 30 ° C. or lower is combined in a single fiber, and one or both of the components 1 and 2 contain a polyorganosiloxane component. Contains 0.05% or more,
In cross section, the block copolymer contains at least 2 other components.
It is separated into two parts, and both components 1, 2 occupy a part of the surface of the fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel dividable composite fiber capable of producing a fiber or a fiber structure which is naturally degradable and has excellent flexibility and a large specific surface area and its applied product. Regarding

[0002]

2. Description of the Related Art Conventional synthetic fibers made of synthetic resin have a slow decomposition rate in a natural environment and generate a large amount of heat upon incineration. Therefore, it is necessary to review the natural environment from the viewpoint of protecting the natural environment. For this reason, naturally decomposable fibers made of aliphatic polyesters are being developed and are expected to contribute to environmental protection. Some of the 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. Product desired. In response to such a request, the conventional synthetic fiber,
As a method of splitting splittable conjugate fibers, knitted fabrics, nonwoven fabrics, artificial leather, artificial suede, high performance wiping cloth, high performance filters, etc., which have excellent flexibility and gloss, have been developed and widely used. However, split-type composite fibers have not yet been proposed in the field of fibers that decompose in the natural environment. The reason is that the combination of the spinning materials (polymers) suitable for splitting and the splitting method have not been known yet.

[0003]

It is an object of the present invention to produce fibers and fibrous structures which are naturally degradable, have improved splittability and have excellent flexibility and large specific surface area. The present invention is to provide a new composite fiber and its applied products.

[0004]

The above object of the present invention is to provide an aliphatic polyester-based conjugate fiber and its applied product which satisfy all of the following items (1), (2), (3) and (4). To be achieved. (1) A crystalline polymer [1] of an aliphatic polyester having a melting point of 140 ° C. or higher, a crystalline segment (H) of the aliphatic polyester having a melting point of 140 ° C. or higher, and 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 the single fiber. (2) One or both of the polymer [1] and the polymer [2] contain a polyorganosiloxane component in an amount of 0.05% by weight or more. (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.

Here, the aliphatic polyester means (1)
Hydroxyalkylcarboxylic acids such as glycolic acid, lactic acid and hydroxybutylcarboxylic acid, (2) aliphatic lactones such as glycolide, lactide, butyrolactone and caprolactone, (3) ethylene glycol,
Aliphatic diols such as propylene glycol, butanediol, hexanediol, etc., (4) polyethylene glycol, polypropylene recall, polybutylene ether, polyalkylene glycols such as copolymers thereof, (5) diethylene glycol, triethylene glycol Oligomers of polyalkylene ethers such as ethylene / propylene glycol, bishydroxyethoxybutane, and (6) polyalkylene carbonate glycols such as polypropylene carbonate, polybutylene carbonate, polyhexane carbonate, polyoctane carbonate, polydecane carbonate, and These oligomers, such as (7) succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid. A main component, that is, 50% by weight or more (particularly 60% or more) of a component derived from an aliphatic polyester polymerization raw material such as an aliphatic dicarboxylic acid, and a homopolymer of the aliphatic polyester, a block of the aliphatic polyester, or / And random copolymer,
And other components in the aliphatic polyester, such as aromatic polyester, polyether, polycarbonate, polyamide, polyurea, polyurethane, polyorganosiloxane, etc. up to 50% by weight (block or / and random)
Includes all copolymers and / or mixtures.

The purpose of modifying the aliphatic polyester by copolymerization or mixing is to lower the crystallinity, lower the melting point (lower the polymerization temperature and molding temperature), improve the melt fluidity, impact resistance,
Improvement of flexibility and elastic recovery, heat resistance, decrease or increase of glass transition temperature and heat shrinkage, improvement of friction coefficient, dyeability, hydrophilicity and water repellency, improvement of adhesion with other components, decomposability Improvement or suppression may be mentioned.

The composite fiber of the present invention is obtained by combining (bonding) a crystalline polymer [1] of an aliphatic polyester having a melting point of 140 ° C. or higher with an aliphatic polyester block copolymer [2] having a specific structure. There is. Here, the segment is a part of the polymer molecular chain and is sometimes called a block.

Specific examples of preferred polymers [1] include poly L-lactic acid (melting point 175 ° C.), poly D-lactic acid (175 ° C.), polyhydroxybutyrate (180 ° C.).
C.), homopolymers such as polyglycolic acid (at 230.degree. C.), and those obtained by copolymerizing and / or mixing a small amount of other components. Generally, in block copolymerization, changes in crystallinity and melting point are gradual, and the proportion of the copolymerization component is 50% or less, particularly 1 to 40%, often 1 to 30%.
% Is preferable, but in random copolymerization, changes in crystallinity and melting point are remarkable, and the proportion of the copolymerization component is preferably 0.5 to 20%, particularly preferably 1 to 10%. Of course, changes in melting point and crystallinity due to copolymerization greatly vary depending on the copolymerization component, so it is necessary to pay attention to the melting endothermic amount and melting point of crystals by DSC. The changes in melting point and crystallinity due to the mixing of other components also vary considerably depending on the mixing components and the mixing ratio, but they are often not as remarkable as in random copolymerization.

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, most preferably in the range of 80,000 to 200,000. Here, the melting point is a scanning differential calorimeter (hereinafter referred to as DSC).
Of a sample that has been sufficiently stretched or / and heat treated and dried, and the endotherm of the polymer crystal melted when measured under the conditions of a sample weight of about 10 mg, a temperature rising rate of 10 ° C./min in nitrogen. It is the peak temperature. FIG.
The DSC curve is schematically shown in FIG. The figure shows a measurement example of a quenched sample that is hardly crystallized, 4 shows a change in baseline due to glass transition, 5 shows an exothermic peak of crystallization due to heating during measurement, and 6 shows an endothermic peak due to melting of crystal. Show. In the fully crystallized sample, the baseline change 4 and the exothermic peak 5 due to the 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 shaded area in FIG. 10) The amount of heat absorbed. The glass transition point is the center temperature of the change 4 of the baseline, but it is the same at the peak value temperature of the main dispersion of the mechanical loss in the measurement of viscoelasticity. The unit of heat absorption is joule / gram (hereinafter referred to as J / g)
And When there are a plurality of melting points in a mixture or block copolymer, the highest melting point is defined as the melting point (in the present invention). However, if the endothermic peak at the highest temperature is negligible, for example, an endothermic amount of less than 5 J / g, and if there is a main peak at a lower temperature, for example, an endothermic amount of 20 J / g or more, the substantial melting point (polymer is Extremely softening and flow starting temperature) may be regarded as the main peak. The melting endotherm is the sum of all melting endotherms.

The polymer [1] is a component having high crystallinity and low heat shrinkability. Suitable examples of the polymer [1] include:
Examples of the crystalline homopolymer and those obtained by copolymerizing and / or mixing a small amount (for example, 30% or less, especially 20% or less) of the second component and the third component to the extent that the crystallinity is not significantly impaired. To be From the viewpoint of strength and heat resistance of the product obtained from the fiber of the present invention, the endothermic amount of the polymer [1] at the time of melting needs to be 20 J / g or more, particularly preferably 30 / g or more, and 40 J / g or more. Is most preferred. The homopolymer of crystalline aliphatic polyester has a melting endotherm of about 50 J / g or more in many cases.
Similarly, from a practical point of view, the melting point of the polymer [1] is 140
Need to be above ℃, preferably above 150 ℃, 160
A temperature of at least ℃ is particularly preferable, and a temperature of at least 170 ℃ is most preferable.

The polymer [2] comprises a crystalline segment (H, sometimes referred to as a hard segment hereinafter) of an aliphatic polyester having a melting point of 140 ° C. or higher, and an aliphatic polyester having a melting point of 120 ° C. or lower and a glass transition point of 30 ° C. or lower. A block copolymer in which a polyester segment (S, which may be referred to as a soft segment hereinafter) is bonded, and due to its structure, it is significantly shrunk by heating. As a result, the polymer [1] and the polymer [2] are The fibers are easily separated and the divided fibers become thin. For high shrinkage, the hard segment is preferably strong and its melting point must be 140 ° C or higher.
Or higher, particularly preferably 160 ° C. or higher, 170
Most preferred is above ℃. On the other hand, the softer the soft segment is, the larger the heat shrinkage is, which is preferable. In the case of crystalline, the melting point needs to be 120 ° C or lower, 100 ° C or lower is preferable, 90 ° C or lower is particularly preferable, and 80 or lower or non-crystalline (non-crystalline). Crystallinity is the most preferred. For example, when treated with water at 100 ° C., if the melting point of the soft segment is 100 ° C. or less, the polymer [2] shrinks strongly. 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 lower, and particularly preferably 0 ° C. or lower. 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 having a melting point of 120 ° C. or lower and a glass transition point of 0 ° C. or lower, which are particularly suitable for the soft segment of the polymer [2], include polycaprolactone, polyethylene succinate, polyethylene adipate, and polyethylene sebacate. Polyethylene azelate, polyethylene decanate, polypropylene succinate, polypropylene adipate, polypropylene sebacate, polypropylene azelaate, polypropylene decanate, polybutylene succinate, polybutylene adipate, polybutylene sebacate, polybutylene azelaate, poly 2 to 2 carbon atoms such as butylene decanate, polyhexane succinate, polyhexane adipate, polyhexane sebacate, polyhexane azelaate, polyhexane decaneate And polyalkylene alkylates and their components (random and block) copolymer having a linear or a branched alkyl group of degree. In addition to this, polyester ethers obtained by combining oligomers of polyalkylene glycols such as diethylene glycol, triethylene glycol, ethylene / propylene glycol and the like with an aliphatic dicarboxylic acid are also preferable as the soft segment.

Generally, homopolymers are often crystalline, but by copolymerizing two or more thereof, the soft segment (S) of the block copolymer [2] has a reduced crystallinity or is amorphous. Can be transformed. The molecular weight of the soft segment is not particularly limited, but is, for example, 1000 to 1
50,000, especially 2000 to 100,000 is often preferable.
Most preferred is 000 to 50,000. A plasticizer or the like may be added to further soften the soft segment.

The hard segment (H) of the polymer [2] is a high melting point crystalline segment. Examples of such high melting point aliphatic polyesters are as described above. In order to strengthen this type of hard segment, it is necessary to have high crystallinity. In order to maintain crystallinity, homopolymer is most preferable, and the amount of the second component is suppressed even in the case of modification by copolymerization or mixing. That is, for example, the amount of the second component is preferably 20% or less, particularly preferably 10% or less, most preferably 5% or less. The molecular weight of the hard segment is not particularly limited, but is preferably 5,000 to 200,000, particularly preferably 8,000 to 100,000, and most preferably 10,000 to 50,000.

The hard segment (H) and the soft segment (S) of the polymer [2] are combined to form a block copolymer. The bonding method is not particularly limited, and ordinary chemical bonding may be used. For example, an ester bond, an amide bond, a urethane bond, a urea bond or the like may be used. For example, a low-melting point aliphatic polyester for a soft segment, which has a hydroxyl group at the terminal, may be reacted (polymerized) with lactide or clicolide to form a hard segment. Alternatively, the polyester for the soft segment and the polyester for the hard segment, both of which have a hydroxyl group at the terminal, may be reacted with a dicarboxylic acid anhydride or a halide for subsequent joining. In these cases, the seam is an ester bond. It is also possible to react the terminal hydroxyl group with diisocyanate and connect it with a urethane bond. Hard segment (H) of polymer [2]
The weight ratio of the soft segment (S) to the soft segment (S) is not particularly limited because it differs depending on each component, but in order to make the strength, elastic modulus, heat resistance, heat shrinkability, etc. of the fiber within the preferable range, this ratio is 2 / 8 to 8/2, especially 3/7 to
A range of 7/3 is preferable, and a range of 4/6 to 6/4 is most preferable in many cases. The stronger the hard segment,
The softer the soft segment, the more effective it is in each case.

The molecular weight of the polymer [2] is not particularly limited, but in many cases it is preferably 50,000 or more, particularly preferably 70,000 to 300,000, most preferably 80,000 to 200,000.

The first factor by which the conjugate fiber of the present invention can be split (peeled) relatively easily is the difference in the heat shrinkage force and / or shrinkage ratio between the polymer [1] and the polymer [2]. Is big. The shrinkage rate of the polymer [1] due to boiling water is 20.
% Or less, particularly preferably 15% or less, 10%
The following are the most preferable. Similarly, the shrinkage rate 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, and 2
0% or more is particularly preferable, and 30% or more is most preferable.
Generally, the more soft segments (low melting point component) in the polymer [2], the greater the shrinkage rate. According to the above description, the polymer [1] and the polymer [2] can be selected to easily realize a sufficient difference in shrinkage.

The second reason why the conjugate fiber of the present invention can be relatively easily divided is that one or both of the polymer [1] and the polymer [2] contain a polyorganosiloxane component.
Mutual adhesiveness is low. The polyorganosiloxane has a side chain of an alkyl group and / or an aryl group, and examples thereof include polydimethylsiloxane, polymethylethylsiloxane, polydiethylsiloxane, polymethylphenylsiloxane, and polydiphenylsiloxane. Are often most preferred. The more polyorganosiloxane component in the polymer,
The adhesiveness between the polymer [1] and the polymer [2] is reduced, and peeling is facilitated. The content of the polyorganosiloxane component of at least one of both polymers must be 0.05% by weight or more, preferably 0.1% or more, particularly preferably 0.3 to 8%, and 0.5 The range of ~ 5% is most widely used. In particular, the polyorganosiloxane component is preferably contained in the polymer [2] in a larger amount than in the polymer [1] or used only in the polymer [2]. The method of incorporating the polyorganosiloxane into the polymer [1] and / or the polymer [2] includes a copolymerization method and a mixing method. The copolymerization method may be carried out by reacting (polymerizing) a polyorganosiloxane having a hydroxyl group at the terminal with an aliphatic polyester polymerization raw material, for example, lactide or glycolide, and mixing with an aliphatic polyester having a hydroxyl group at the terminal to form a dicarboxylic acid. An anhydride, a dicarboxylic acid halide, a diisocyanate or the like may be reacted to bond both. For example, a prepolymer obtained by reacting an equimolar amount of diisocyanate with an end hydroxyl group of polysiloxane (having an isocyanate group) can be mixed and reacted with an aliphatic polyester having a hydroxyl group. However, the copolymerization method has a difficult problem of uniformly mixing and reacting a very small amount of silicon compound with a large amount of aliphatic polyester.

The mixing method is a method in which a polyorganosiloxane is mixed with an aliphatic polyester, but the two have poor mutual affinity and it is quite difficult to mix them uniformly. One method of improving affinity is the application of surfactants. Another method is to use 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. It is relatively easy and most practical to uniformly mix the separately produced block copolymer with the aliphatic polyester. is there. It is relatively easy to separately produce this block copolymer because a required amount is small, and thus a special device or method such as a powerful stirring device, an ultrasonic device, or a surfactant can be applied. In this case, the ratio of the polyorganosiloxane component in the block copolymer of the aliphatic polyester and the polyorganosiloxane is 5 to 95%, especially 1
The range of 0 to 90% is preferable, and the range of 20 to 80% is most often used. This block copolymer can be used as a dispersant (surfactant) when dispersing (mixing) the polyorganosiloxane in the aliphatic polyester, has a wide range of applications, and is particularly useful in the present invention.

In the cross section of the fiber 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 are part of the surface of the fiber. Must be occupied. By this composite structure,
The fiber of the present invention can be divided into a plurality of fibers, and a fiber having a small fineness and a special cross section can be obtained. The larger the number of layers of the polymer [1] in the single fiber, the finer the fiber having a large specific surface area. The number of divisions must be two or more, and about 3 to 20 is most widely used. Those with a division number of about 3 to 10 are suitable for dresses, blouses, women's underwear, etc., and those with a number of 4 to 20 are ultra-fine fibers, such as ultra-high density knitted fabrics, nonwoven fabrics, artificial suede, artificial leather, filters, Suitable for wiping cloth and the like.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION FIGS. 1 to 9 show cross sections of composite fibers suitable for the present invention. In the figure, 1 is the polymer [1],
2 is a polymer [2] and 3 is a hollow part. FIG.
Is an example of a 3-layer parallel type and a 3-division type. The parallel type means 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 radial layer of the polymer [2]. Radial refers to one of the components, eg polymer [2], in radial form. 3 is a 9-layer radial type, FIG. 4 is a 9-layer multiple parallel type, FIG. 5 is a petal-shaped 9-layer radial type, FIG. 6 is a combination of radial type and multiple parallel type, and FIG. 7 is a non-circular radial type. , FIG. 8 is a modified multiple parallel type, FIG.
Is an example of the hollow emission type. Besides FIGS. 1-9, a wide variety of composites are possible in accordance with the present invention. In addition to the polymer [1] and the polymer [2], a third component can be compounded. For example, a third polymer may be arranged instead 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.

The composite ratio (cross-sectional area ratio) of 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 20/1 to 1 /
The range of 5 is preferable, and the range of 10/1 to 1/2 is widely used. That is, it is often preferable that the ratio of the low shrinkage component 1 is larger than that of the high shrinkage component 2, and the composite ratio in the range of 10/1 to 1/1 is most widely used.

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 multilobe shape, various non-circular shapes (atypical 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 most widely used.

The fiber of the present invention can be produced by composite spinning of the polymer (1) and the polymer (2) by a melt method, a wet method, a dry method, a dry-wet method or the like. In particular, melt spinning is preferred because of its high efficiency. For melt spinning, for example, a winding speed of 500
~ 2000m / min low speed spinning, winding speed 2000 ~
High speed spinning at 5000m / min, winding speed 5000m /
Ultra-high-speed spinning of min or more is possible, and stretching and heat treatment can be performed as necessary. 3 for low-speed spinning
Approximately 6 to 6 times, in high speed spinning, approximately 1.5 to 2.5 times, and in ultra high speed spinning, stretching is often unnecessary or approximately 2 times or less. A so-called spin draw method in which spinning and drawing are continuously performed can also be preferably applied.

Similarly, a method such as a melt blow method, a flash spinning method or a spun bond method, in which the polymer (1) and the polymer (2) are compounded and spun through an orifice and simultaneously made into a nonwoven fabric, can be applied. .

The conjugate fiber of the present invention may be in any form such as continuous filament, monofilament, multifilament, cut staple, etc. depending on the purpose of use. Among the conjugate fibers of the present invention, those having a large number of silicon components and particularly weakened mutual adhesiveness between the components may show peeling or cracks only by stretching. If it is heated or swelled, peeling / dividing proceeds further. When the releasability is weak, in addition to heating and swelling, a mechanical method such as false twisting, kneading, and tapping may be applied as necessary. A method in which the polymer [2] is dissolved and removed with a solvent and divided is also applicable, but the peeling method is preferable because it causes no weight loss. In general, during fiber production or during processing into a knitted fabric or the like, it is often preferable to suppress peeling to a latent degree, and after forming into a knitted fabric or the like, complete peeling / dividing is often performed, for example, in a dyeing finishing step. This is because ultrafine fibers and ultrafine fibers are easy to cut due to friction during manufacturing or processing and often cause troubles.

The composite fiber of the present invention contains various pigments, dyes, colorants, water repellents, water absorbing agents, flame retardants, stabilizers, antioxidants,
UV absorber, metal particles, inorganic compound particles, crystal nucleating agent,
Lubricants, plasticizers, antibacterial agents, fragrances and other additives can be mixed.

The fibers of the present invention can be used alone or in a mixture with other fibers for producing yarns, strings, ropes, knits, woven fabrics, nonwoven fabrics, papers, composite materials and other structures. When mixed with other fibers, natural organic fibers such as cotton, wool and silk,
It is particularly preferable to use it in combination with a naturally degradable fiber such as an aliphatic polyester fiber because a completely naturally degradable product can be obtained.

[0028]

EXAMPLES In the following examples,% and parts are by weight unless otherwise specified. The molecular weight of the aliphatic polyester is
In GPC analysis of a 0.1% chloroform solution of a sample, it is a weight average value of dispersion of a high molecular component excluding a component having a molecular weight of 1,000 or less.

[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 0.05 part of Irganox 1010, an antioxidant of Ciba-Geigy Co. Mix, melt and stir polymerize in a twin-screw extruder at 188 ° C for 15 minutes in a nitrogen atmosphere, extrude from a die and form cooling chips, and then process in a nitrogen atmosphere at 140 ° C for 4 hours (solid phase polymerization).
Then, it was washed with acetone containing 0.1% of hydrochloric acid, washed with acetone 5 times, and then dried 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%, and a melting point of 17
Melting endotherm when fully oriented and crystallized at 4 ° C is 55
J / g, melting point, crystallinity, etc. are almost the same as polylactic acid homopolymer, but melt flowability and drawability are excellent, melt composite spinning is easy, and shrinkage ratio of the drawn yarn by boiling water is often It is about 10 to 15%.

A random copolymer of polybutylene succinate and polybutylene adipate in a molar ratio of 4/1, having hydroxyl groups at both ends with a molecular weight of 125,000 and a melting point of 93 ° C. 2
5 parts, 76 parts of L-lactide, and 80 ppm of tin octylate were mixed and polymerized in the same manner as the polymer P1 to give about 3 parts of polylactic acid and polybutylene succinate / adipate.
A block copolymer P2 of / 1 was obtained. Polymer P2 has a molecular weight of 117,000 and has two melting endothermic peaks by DSC. Its melting point and melting endotherm are 168 ° C. (36 J /
g) at 86 ° C. (6.5 J / g), it is estimated that they correspond to the polylactic acid segment and the polybutylene succinate / adipate copolymer segment, respectively, but the melting point (typical value) of this polymer is 168. ℃. The shrinkage ratio of the drawn yarn obtained from the polymer P2 due to boiling water is about 30 to 70% in most cases. L-lactide 1
1/50 mol of octyl alcohol and 100 ppm of tin octylate were mixed per mol, and the mixture was polymerized in the same manner as the polymer P1.
This polylactic acid is referred to as polymer P3. After mixing and reacting an equimolar amount of hexane diisocyanate with the polymer P3 melted at 180 ° C., the obtained prepolymer having an isocyanate group at the end is added with polydimethylsiloxane having a hydroxyl group at one end and a molecular weight of 5500. Mole mixed,
After melt-mixing with a twin screw extruder at 180 ° C., element 120
Polylactic acid / polydimethylsiloxane obtained by reacting for 30 minutes while passing through a static mixer having about 55/45
The block copolymer of the above is referred to as polymer P4.

Polymer P2 was melted at 220 ° C. and fed, while polymer P4 melted at 220 ° C. was 3%.
After mixing and further mixing in a Kenix type static mixer having 60 elements, the mixture was fed to the composite spinneret by a metering pump. On the other hand, polymer P1 is heated at 220 ° C with a screw extruder.
Melted and supplied to the composite spinneret with a metering pump, the polymer P1 as the component 1, the polymer P2 / polymer P4 mixture as the component 2, and the radiation ratio as shown in FIG. 2 at the composite ratio 4/1 (volume ratio). Combined, spun out from an orifice with a diameter of 0.20 mm, cooled in air and oiled 1500 m
At a speed of / min and stretched at 80 ° C by a factor of 3,9,
Then heat treated at 100 ° C under tension to 75 denier /
A drawn filament F1 of 25 filaments was obtained.

For comparison, polymer P1 and polymer P2
(Without using a silicon compound), the following drawn yarn F
The conjugate fiber obtained in the same manner as 1 is used as a drawn yarn F2 (comparative example). A circular knitted fabric was produced using the drawn yarn F1, put into boiling water, boiled for 15 minutes, taken out, dried, and brought into contact with a rotary roll around which sandpaper was wound to obtain a raised knitted fabric K1. The napped fibers in the knitted fabric K1 obtained from the fiber of the present invention were almost divided, and the knitted fabric had an extremely soft touch. Similarly, the napped fibers in the raised knit K2 obtained by boiling, drying, and raising the knit obtained from the drawn yarn F2 of the comparative example were hardly divided, and the feel of the knit K2 was hard. .

[Example 2] The same procedure as in the above polymer P2 except that a hydroxyl group-terminated molecular weight was 128,000 and a melting point was 6
To 25 parts of polycaprolactone at 0 ° C., L-lactide 76
A block copolymer of polylactic acid / polycaprolactone = about 3/1 obtained by reacting parts of the same is designated as P5. The molecular weight of the polymer P5 is 103,000, and the melting point and melting endotherm by DSC are 166 ° C. (35 J / g) and 52 ° C. (6.6
J / g), the melting point (typical value) is 166 ° C., and the shrinkage of the drawn yarn obtained from this with boiling water is 30 in most cases.
It is about 70%. The conjugate fiber obtained in the same manner as the conjugate fiber F1 of Example 1 except that the polymer P5 was used instead of the polymer P2 is designated as F3. Using the conjugate fiber F3, a raised knit K3 was obtained in the same manner as the raised knit K1 of Example 1 below. The raised knitted fabric K3 according to the present invention was composed of fine fibers in which the naps were divided, and had an extremely soft touch.

[0034]

Industrial Applicability According to the present invention, a composite fiber which can be decomposed in a natural environment and can be split by heating or mechanical means was 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 leathers, and other fiber structures can be obtained. Materials (for example, high-performance filters, water absorbing materials, oil absorbing materials, etc.)
It can be applied to fields such as by making the most of its features and characteristics. Especially agriculture, horticulture, civil engineering, fisheries, machinery industry,
It is extremely useful for things such as packaging, household items, and other disposable items, as well as applications that require natural decomposition, and is expected to greatly contribute to environmental protection.

[Brief description of drawings]

FIG. 1 is an example of a cross-section of a three-layer side-by-side conjugate fiber useful in the present invention.

FIG. 2 is an example of a cross-section of a five-layer radiant conjugate fiber useful in the present invention.

FIG. 3 is an example of a cross section of a 9-layer radiant conjugate fiber useful in the present invention.

FIG. 4 is an example of a cross section of a 9-layer side-by-side conjugate fiber useful in the present invention.

FIG. 5 is an example of a cross section of a petal-shaped radial composite fiber useful in the present invention.

FIG. 6 is an example of a cross-section of a combined side-by-side radiant composite fiber useful in the present invention.

FIG. 7 is an example of a cross-section of a non-circular radial bicomponent fiber useful in the present invention.

FIG. 8 is an example of a cross-section of a non-circular side-by-side conjugate fiber useful in the present invention.

FIG. 9 is an example of a cross section of a hollow radiant conjugate fiber useful in the present invention.

FIG. 10 is an example of a DSC curve for a crystalline polymer.

[Explanation of symbols]

1 Polymer [1] 2 Polymer [2] 3 Hollow part 4 Change in baseline due to glass transition 5 Exothermic peak due to crystallization 6 Endothermic peak due to melting

Front Page Continuation (72) Inventor Yoshikazu Kondo 2-35-131, Kokutetsu, Hofu City, Yamaguchi Prefecture (72) Inventor Hiroshi Kajiyama 4-1 Kanebocho, Hofu City, Yamaguchi Prefecture

Claims (4)

[Claims] 1. An aliphatic polyester-based conjugate 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 the aliphatic polyester having a melting point of 140 ° C. or higher, and 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 the single fiber. (2) One or both of the polymer [1] and the polymer [2] contain a polyorganosiloxane component in an amount of 0.05% by weight or more. (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. 2. A crystalline polymer of an aliphatic polyester [1]
Is selected from the group of "polylactic acid, poly-3-hydroxybutyrate, polyglycolide and modified polyesters containing them as a main component", and the polyorganosiloxane component is selected from the group of "alkyl group and aryl group". The composite fiber of claim 1, which is a polysiloxane having at least one selected group. 3. The composite structure is selected from the group of “radial type, parallel type, and combination thereof”.
The described composite fiber. 4. A fiber and a fiber structure in which the composite fiber according to any one of claims 1 to 3 is used as at least a part and the composite fiber is divided.