JPH1060738A - Splittable conjugate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain such a conjugate fiber as to be easy to treat polymer component(s) removed therefrom, and capable of giving fibrous sheets small in pore size. SOLUTION: This splittable conjugate fiber is composed of two or more kinds of biodegradable polymer component including crystalline one(s) and has such structure that different kind(s) of biodegradable polymer component is roughly divided into two or more portions by the identical kind of biodegradable polymer component, and also at least one biodegradable polymer component contains polymer component(s) hard to be removed by a remover for this biodegradable polymer component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite fiber which can be made into a fine fiber.

[0002]

2. Description of the Related Art Conventionally, composite fibers generally called sea-island fibers have been known. This sea-island fiber is a fiber cross-section in which one polymer component is dispersed in the form of an island in another polymer component (resulting in a sea-like shape). By extracting and removing the sea-like polymer component, By generating fine fibers consisting of island-shaped polymer components or extracting and removing island-shaped polymer components, porous fibers consisting only of sea-like polymer components can be formed. In the case of (1), artificial leather has been used, and in the case of (2), filtration and liquid retention materials have been mainly used.

However, the sea-like polymer component and / or the island-like polymer component constituting the sea-island fiber are all synthetic polymers, such as polyamide, polyester, polyolefin and polystyrene, which are hardly decomposed in nature. Because there was, the solvent that extracted the synthetic polymer was recovered,
Needed to be processed. However, a great deal of labor was required to recover and treat the solvent from which the synthetic polymer was extracted.

Further, after forming a fiber sheet such as a non-woven fabric using the sea-island fiber, a sea-like polymer component of the sea-island fiber is extracted and removed, and a thin fiber composed of the island-like polymer component is used. A method of forming a configured fiber sheet is known, but a fiber sheet formed by such a method is:
Regardless of the method used, the fiber sheet has a large pore diameter, and its use may be limited.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a fiber sheet having a small pore size, in which the polymer component removed from the fibers can be easily treated. It is an object of the present invention to provide a composite fiber that can be used.

[0006]

Means for Solving the Problems The composite fiber capable of being made into a fine fiber (hereinafter, simply referred to as "composite fiber") of the present invention is a crystalline biodegradable polymer component (hereinafter, referred to as "crystalline component").
Comprising two or more types of biodegradable polymer components, wherein different types of biodegradable polymer components are substantially divided into two or more by the same type of biodegradable polymer component, and at least one The biodegradable polymer component contains a polymer component that is hardly removable (hereinafter, referred to as a “hard-removable component”) as a remover for the biodegradable polymer component.

[0007] Therefore, even if the biodegradable polymer component of the conjugate fiber is removed and the removed material is left or discarded in the natural world, it does not decompose and does not destroy the environment. It is. Further, the conjugate fiber of the present invention can be divided between the biodegradable polymer components, and after the division,
Obtained by removing this biodegradable polymer component, the fine fibers comprising the hard-to-remove component are fine, even if the fine fibers are in a bundle form, compared to a bundle of fine fibers obtained from conventional sea-island fibers. Since the fine fibers can be dispersed more easily, if the composite fiber of the present invention is used,
A uniform fiber sheet having a smaller pore size can be formed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Since the conjugate fiber of the present invention contains a crystalline component, the conjugate fiber itself is excellent in strength and the fiber sheet containing the conjugate fiber or the fine fiber generated from the conjugate fiber Is also excellent in strength.

The crystallinity of the crystalline component means that it indicates a glass transition temperature, a crystallization temperature, and a melting temperature in a thermal analysis method such as a differential scanning calorimeter (DSC). Although this crystalline component is not particularly limited,
For example, an aliphatic polyester-based polymer, an aliphatic polyesteramide-based copolymer, or D-lactic acid is 0.05 to 30%.
A lactic acid-based copolymer in which mol% copolymerization or L-lactic acid is copolymerized in an amount of 0.05 to 30 mol% can be used. Among these crystalline components, aliphatic polyester-based polymers and aliphatic polyesteramide-based copolymers are thermoplastic and can act as an adhesive component before splitting and generating fine fibers, or after generating fine fibers. Therefore, it can be suitably used. In addition, lactic acid-based copolymers are excellent in heat resistance and therefore can be suitably used. In addition, these crystalline components
Both are hydrolyzed with an alkaline solution and can be easily removed, so they are easy to handle in the process.Moreover, by neutralizing the solution hydrolyzed with an alkaline solution with an acid, it is possible to treat with activated sludge. It is kind.

Examples of the aliphatic polyester polymer include polymers or copolymers of α-hydroxy acids such as glycolic acid and lactic acid, and ω-hydroxyalkanoate polymers such as ε-caprolactone and β-propiolactone. Coalescing or copolymer, 3-hydroxypropionate, 3
Polymers or copolymers of β-hydroxyalkanoates such as -hydroxybutyrate, 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxyvalerate, 4-hydroxybutyrate, polyethylene oxalate, polyethylene Polycondensates of diols and dicarboxylic acids such as succinate, polyethylene adipate, polyethylene azelate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, polybutylene sebacate, polyhexamethylene sebacate, and polyneopentyl oxalate Or a copolymer, as the aliphatic polyester amide copolymer, the above aliphatic polyester polymer, capramide,
There are copolymers of aliphatic amides such as tetramethylene adipamide, undecanamide, laurolactamide, and hexamethylene adipamide. Among these, aliphatic polyester-based condensation polymers or copolymers of diols and dicarboxylic acids, especially polyethylene succinate and polybutylene succinate are preferred crystalline components because of their excellent spinnability.

[0011] Examples of the lactic acid-based copolymer include, for example,
There are a copolymer of D-lactic acid and L-lactic acid, a copolymer of D-lactic acid and hydroxycarboxylic acid, a copolymer of L-lactic acid and hydroxycarboxylic acid, and the like. Among these, D-
A copolymer of lactic acid and L-lactic acid in a molar ratio of 0.05: 99.95 to 30:70 has excellent heat resistance.
It can be suitably used.

The aliphatic polyester polymer and / or
Alternatively, when an aliphatic polyesteramide-based copolymer and a lactic acid-based copolymer are combined with each other, a fine fiber is easily generated by dividing the crystalline components, which is a preferable combination. Therefore, it is preferable to combine polyethylene succinate and / or polybutylene succinate with a copolymer of D-lactic acid and L-lactic acid in a molar ratio of 0.05: 99.95 to 30:70. Combination.

The conjugate fiber of the present invention comprises two or more types of biodegradable polymer components containing the above-mentioned crystalline components. This combination may be composed of only two or more crystalline components, or may include an amorphous biodegradable polymer component (hereinafter, referred to as “amorphous component”). When only the former crystalline component is used, the conjugate fiber itself is excellent in strength, and the fiber sheet containing the conjugate fiber or the fiber sheet containing fine fibers generated from the conjugate fiber is also excellent in strength. When a crystalline component is also contained, the biodegradability is more excellent.

The non-crystallinity of the non-crystalline component means that, for example, in a thermal analysis method such as a differential scanning calorimeter (DSC), it shows a glass transition temperature but does not show a crystallization temperature and a melting temperature. Good, as the amorphous component, for example, D
-Lactic acid is copolymerized from 30.05 to 69.95 mol%, or L-
There is a lactic acid-based copolymer in which lactic acid is copolymerized from 30.05 to 69.95 mol%. More specifically, there are a copolymer of D-lactic acid and L-lactic acid, a copolymer of D-lactic acid and hydroxycarboxylic acid, a copolymer of L-lactic acid and hydroxycarboxylic acid, and the like. Above all, those obtained by copolymerizing D-lactic acid and L-lactic acid at a molar ratio of 30.5: 69.95 to 69.95: 30.05 are more excellent in biodegradability and can be suitably used. This amorphous lactic acid-based copolymer is preferably used in combination with the aliphatic polyester-based polymer and the aliphatic polyesteramide-based copolymer, which are the above-mentioned crystalline components, because the fiber easily divides into fine fibers. It is a combination. Therefore, polyethylene succinate and / or polybutylene succinate, D-lactic acid and L-lactic acid are 3
It is a preferred combination to combine with a copolymer having a molar ratio of 0.05: 69.95 to 69.95: 30.05.

The conjugate fiber of the present invention is composed of two or more types of biodegradable polymer components containing a crystalline component, and more than two different types of biodegradable polymer components are formed by the same type of biodegradable polymer component. , The biodegradable polymer components can be separated and separated.

The same kind of biodegradable polymer component is obtained by spinning a side-by-side type conjugate fiber from a target resin and then stretching the side-by-side type conjugate fiber with a finger to apply a shearing force to the two fibers. It refers to those that are difficult to split. Two different biodegradable polymer components are obtained by spinning side-by-side type composite fibers from the target resin, stretching the side-by-side type composite fibers with a finger, and applying shear force. That can be divided into fibers.

The divided state includes a case where the crystalline component and / or the amorphous component is substantially divided by the crystalline component, and a case where the crystalline component and / or the amorphous component is substantially divided by the amorphous component. There is.

The at least one biodegradable polymer component contains a hard-to-remove component as a remover for the biodegradable polymer component. Therefore, after dividing between the biodegradable polymer components, if this biodegradable polymer is removed, it is possible to generate fine fibers composed of the hardly removable component, and the fine fibers composed of the hard removable component are Because it is obtained by removing the biodegradable polymer component after being divided, it is a bundle, but it is finer than the conventional bundle of fine fibers, and the fine fibers can be more easily dispersed. Therefore, a uniform fiber sheet having a smaller hole diameter can be formed.

Examples of the biodegradable polymer component remover include a solvent, an enzyme, and a microorganism. Among them, the solvent is preferably used because it has a high removal rate and is easy to handle. Among these solvents, aqueous solvents are more suitable for production because they are easier to handle and process, and an alkali solution from which a biodegradable polymer component is easily extracted can be most preferably used. In the case of removing with an alkali solution, the environment is not damaged if the solution is neutralized with an acid solution and discarded after extraction.

The term "removability" means that the removal rate of the biodegradable polymer component to be removed is one half or less of the removal rate, and the difficulty removal component varies depending on the remover for the biodegradable polymer component. However, for example, when the biodegradable polymer component is removed with a suitable alkali solution, the hard-to-remove component includes polyethylene, polypropylene, polyolefin such as polystyrene, nylon 11, nylon 12, nylon 6,
One or more kinds of nylons such as nylon 66 and modified nylon, polyesters such as polyester and modified polyester, ester elastomers, olefin elastomers, and urethane elastomers can be used. Among them, polyolefin resins are excellent in alkali resistance and hardly cause a decrease in mass, so that they can be suitably used.

The hard-to-removable component only needs to be at least one kind, but includes two or more hard-to-removable components including a hard-to-removable component having a melting point difference of 10 ° C. or more as a different hard-to-removable component. In this case, the strength of the fiber sheet can be improved by fusing at least one type of hard-to-removable component other than the hard-to-removable component having the highest melting point, or the film can be concealed by melting into a film. It is a suitable combination of hard-to-remove components because it can improve the removability. It should be noted that the type of the hardly removable component is determined based on the melting point.

Further, it is more preferable that the hard-to-remove component comprises only a polyolefin-based resin component because it has excellent chemical resistance and can be adapted to various uses. Especially,
When polypropylene is contained as the polyolefin-based resin component, the separation performance can be enhanced by electretization, so that it can be suitably used. Also,
When it contains polypropylene, it is fused or densified so as to improve the strength of the fiber sheet by fusing without adversely affecting the polypropylene and / or to improve the concealing property. Preferably, it contains high density polyethylene.

The conjugate fiber of the present invention will be described below with reference to FIG. FIG. 1 shows a conjugate fiber obtained by dividing one kind of crystalline component by one kind of amorphous component.
The same split state applies to a composite fiber composed of two types of amorphous components and two or more types of crystalline components, or a composite fiber composed of two or more types of amorphous components and one or more types of crystalline components. Is fine.

FIG. 1 (a) shows a conjugate fiber in which a crystalline component 2 is divided into two by an amorphous component 1, and a hardly removable component is contained in any of the biodegradable polymer components. After splitting the composite fiber into one fiber having an amorphous component 1 as a sea component and two fibers having a crystalline component 2 as a sea component, the amorphous component 1 and the crystalline component 2 are separated. If removed, a fine fiber composed of the hardly removable components 3 and 4 can be generated. The division of the crystalline component 2 by the amorphous component 1 does not need to be divided into two, and as shown in FIGS. 1B to 1E, when the crystalline component 2 is divided into three or more, the composite fiber is divided. The resulting fiber is finer, and the fine fiber bundle comprising the hard-to-removal component obtained by removing the biodegradable polymer component of the generated fiber is preferable because it is smaller. Preferably, the fiber is divided into four or more, and the average fiber diameter of the fiber before removal of the biodegradable polymer component (in the case of a fiber having an irregular cross-sectional shape, a value converted into a circular cross-section) is
20 μm or less, preferably 10 μm or less, more preferably 6 μm
It is preferable to design so as to be not more than m.

The average fiber diameter of the fine fibers comprising the hard-to-remove component obtained by removing the biodegradable polymer component is 3 μm.
It is preferably at most 2 μm, more preferably at most 2 μm, most preferably at most 1 μm. If the number of the fine fibers composed of the hardly removable component is small, the amount of the fine fibers is small and only a fiber sheet having a low fiber density can be obtained, so the biodegradable polymer component is removed and the hardly removable component is removed. 500 or more fine fibers consisting of
It is preferable that the hard-removable components are dispersed in an island shape so that zero or more can be generated. The fine fibers comprising the hard-to-remove component are preferably uniformly dispersed in the biodegradable polymer component, but may be unevenly distributed. Further, the cross-sectional shape of the fine fiber comprising the hard-to-remove component does not need to be circular, and may be elliptical, elliptical, polygonal, or the like, and is not particularly limited.

The hardly removable component may be contained in at least one biodegradable polymer component, but if contained in all the biodegradable polymer components, the biodegradable component to be removed is removed. It is most preferable because the amount of the components can be reduced and a fiber sheet having a high fiber density can be obtained. The hard-to-removable component contained in one biodegradable polymer component does not need to be one kind, and two or more hard-to-remove products may be mixed. If the hard-to-removable component contained in each of the coalesced components consists only of the same type of polymer component, when the fine fibers of the hard-to-removable component are generated, the fine fibers of the same hard-to-removable component are densely packed. By melting the fine fibers or melting by the external environment, it is possible to impart various properties such as making the pore diameter of the fiber sheet more uniform or partially changing the degree of hydrophilicity. It is.

The division by the amorphous component 1 is preferable if the amorphous component 1 is exposed to the fiber surface and completely divided, since fine fibers are more likely to be generated. It is not necessary that the component 1 is exposed to the fiber surface and is completely divided. If the end of the amorphous component 1 is within 5 μm from the fiber surface, the hardly removable component is It can be divided into fibers composed of biodegradable polymer components. It is preferable that the cross-sectional shape of the amorphous component 1 is linear, because it is easier to divide and to generate fine fibers, but it is preferable that the cross-sectional shape be a curved shape or a fan shape as shown in FIG. Is also good. As shown in FIG. 1 (e), if the cross-sectional shape of the amorphous component 1 is a sector shape, the size of all the fibers composed of the biodegradable polymer component including the hard-to-remove component generated is substantially the same. It is possible to obtain a more uniform fiber sheet because the fine fibers comprising the hard-to-removal component obtained by removing the biodegradable polymer component of the fiber are composed of only fiber bundles of the same size. Is preferred. The cross-sectional shape of the conjugate fiber need not be circular, but may be elliptical, elliptical, polygonal, or the like, and is not particularly limited.

Such a conjugate fiber is appropriately combined with a normal conjugate spinning method and / or a mixed spinning method to obtain
It can be easily spun. For example, the composite fiber having the cross-sectional shape illustrated in FIG. 1 (e) extrudes a mixed melt of an amorphous component and a hard-to-removal component from the small holes, and positions the mixed fibers between the small holes for extruding the mixed melt. After extruding a mixed melt of the crystalline component and the hard-to-removable component from the small holes, the composite melt can be obtained by stretching.

Using the conjugate fiber of the present invention as described above, a woven fabric, a knitted fabric, a non-woven fabric, etc. are formed and then the conjugate fiber is divided into fine fibers, or the conjugate fiber is divided into fine fibers. After the generation, the fiber sheet is formed, whereby a fiber sheet having a small pore size and excellent uniformity can be formed.

The fiber sheet using the conjugate fiber of the present invention contains fine fibers composed of components that are difficult to remove, and has a small pore size and excellent uniformity. Suitable for various applications such as base cloth, mask, medical protective material, battery separator, air conditioning or liquid filter, synthetic or artificial leather base material, outer garment material, interior material, cleaning material, liquid retaining material, etc. it can. In addition, dyeing process, raising process, laminating process, molding process,
Various functions can be added by embossing or chemical or physical surface treatment to suit various applications.

Examples of the present invention will be described below, but the present invention is not limited to the following examples. In addition, melting | fusing point, an average pore diameter, air permeability, etc. shown in the Example were calculated | required by the following method.

Melting point: Using a differential scanning calorimeter (manufactured by Mac Science, Model DSC-3100), the temperature was raised at a rate of 10
The temperature was measured under the condition of ° C./min, and the temperature at which an extreme value was obtained in the obtained melting heat curve was defined as the melting point.

Average pore size: mercury porosimeter (CARL)
O ERBA STRUMENTAZIONE P
OROS METER 2000) by a mercury intrusion method.

Air permeability: In accordance with JIS P8117, the nonwoven fabric is made of a standard Gurley Densometer (Gurley Densometer).
The measurement was carried out by attaching to a thermometer. That is, 64
The average number of seconds required for 100 ml of air to pass through a non-woven fabric having an area of 5 mm ² was measured.

[0035]

【Example】

Example 1 Dry-blended polylactic acid-based copolymer (molar ratio; L-lactic acid: D-lactic acid = 95: 5) and high-density polyethylene (MI = 18) at a weight ratio of 6: 4. Of the obtained system (A resin component unit), polybutylene succinate and polypropylene (MI = 65) in a mass ratio of 6:
Using the system (B resin component unit) dry-blended in 4, melt spinning at a spinning temperature of 240 ° C, and a fan-shaped A resin component unit in which high-density polyethylene is uniformly dispersed,
A fan with a fineness of 0.89 mg / m having a cross section similar to that of FIG. 1 (e) was obtained by dividing a fan-shaped B resin component unit in which polypropylene was uniformly dispersed into eight pieces. The volume ratio of the A resin component unit and the B resin component unit constituting this yarn was 1: 1. Next, the yarn was drawn in a warm bath at 90 ° C. to a fineness of 220 μg / m, and then cut into 10 mm to form a conjugate fiber.

Next, 100% of the composite fiber is used,
A fiber web having an areal density of 50 g / m ² was formed by a wet papermaking method. Next, this fiber web was heat-treated in an oven at 125 ° C. and fused with the polybutylene succinate component of the conjugate fiber, and then placed on a net (0.14 mm in wire diameter) with an opening of 0.147 mm, A cycle of discharging a water flow at a pressure of 11.8 MPa from a nozzle plate having a nozzle having a diameter of 0.13 mm and a pitch of 0.6 mm, inverting the same, and discharging a water flow at a pressure of 11.8 MPa from a similar nozzle plate is defined as one cycle. The composite fiber was divided at the same time as being entangled by two-cycle treatment, and fine fibers were generated to form an entangled fiber web. The average fiber diameter of the fibers constituting the entangled fiber web was 4 μm.

Next, the entangled fiber web is heated to a temperature of 80
The polylactic acid-based copolymer and the polybutylene succinate were decomposed and extracted by immersing in a 14 mass% aqueous sodium hydroxide solution at 20 ° C. for 20 minutes, and a polypropylene ultrafine fiber bundle having an area density of 20 g / m ² and a thickness of 100 μm ( Average fineness 5.
8 μg / m, average fiber diameter 0.4 μm, melting point 166 ° C.) and polyethylene ultrafine fiber bundle (average fineness: 5.8 μg / m, average fiber diameter 0.2 μm, melting point 128 ° C.) A fiber diameter of 0.3 μm) was formed.

The fiber web in which the ultrafine fiber bundle of polypropylene and the ultrafine fiber bundle of polyethylene is entangled is placed on an iron plate having a thickness of 10 mm in a perch and an electric wire located 5 mm above the iron plate. An ultrasonic wave having a frequency of 19.5 kHz and an amplitude of 50 μm is transmitted from a distorted ultrasonic horn.
Irradiation was performed for 2 seconds to obtain a nonwoven fabric in which polypropylene ultrafine fibers having an average fiber diameter of 0.4 μm and polyethylene ultrafine fibers having an average fiber diameter of 0.2 μm were uniformly dispersed.

Next, this nonwoven fabric was subjected to a Shore B hardness of 80.
1.5 kN / c linear pressure between resin roll and metal roll
m at a speed of 10 m / min, and a surface density of 20 g /
m ² , a 50 μm thick polypropylene microfiber having an average fiber diameter of 0.4 μm and a polyethylene ultrafine fiber having an average fiber diameter of 0.2 μm are uniformly dispersed. The average pore diameter is 0.20 μm and the air permeability is 2.
A nonwoven fabric of 5 sec / 100 ml was obtained.

Next, this nonwoven fabric is sandwiched between smooth glass plates so as not to cause surface shrinkage during heating, and heat-treated in an oven at 130 ° C. for 30 minutes to partially fuse only the polyethylene ultrafine fibers. , Average pore size 0.16 μm,
A nonwoven fabric having an air permeability of 40 sec / 100 ml was obtained.

Example 2 A dried polylactic acid-based copolymer (molar ratio: L-lactic acid: D-lactic acid = 95: 5) and high-density polyethylene (MI = 18) were mixed at a mass ratio of 6: 4. Using a system (A resin component unit) dry-blended with a polybutylene succinate and a polypropylene (MI = 124) at a mass ratio of 6: 4 (B resin component unit) at a spinning temperature of Melt spinning at 240 ° C,
The fan-shaped B resin component unit in which polypropylene is uniformly dispersed is divided into eight by the fan-shaped A resin component unit in which high-density polyethylene is uniformly dispersed, and has a cross-sectional shape similar to that of FIG. A yarn with a fineness of 0.88 mg / m was obtained. The volume ratio of the A resin component unit and the B resin component unit constituting this yarn was 1: 1. Next, the thread is
After stretching in a warm bath at a temperature of 240 ° C. to a fineness of 240 μg / m,
It was cut to 0 mm to form a composite fiber.

Next, 100% of the composite fiber is used,
A fiber web having an areal density of 50 g / m ² was formed by a wet papermaking method. Next, this fiber web was heat-treated in an oven at 125 ° C. and fused with the polybutylene succinate component of the conjugate fiber, and then placed on a net (0.14 mm in wire diameter) with an opening of 0.147 mm, A cycle of discharging a water flow at a pressure of 11.8 MPa from a nozzle plate having a nozzle having a diameter of 0.13 mm and a pitch of 0.6 mm, inverting the same, and discharging a water flow at a pressure of 11.8 MPa from a similar nozzle plate is defined as one cycle. The composite fiber was divided at the same time as being entangled by two-cycle treatment, and fine fibers were generated to form an entangled fiber web. The average fiber diameter of the fibers constituting the entangled fiber web was 4.2 μm.

Next, the entangled fiber web is heated to a temperature of 80
The polylactic acid-based copolymer and the polybutylene succinate were decomposed and extracted by immersing in a 14 mass% aqueous sodium hydroxide solution at 20 ° C. for 20 minutes, and a polypropylene ultrafine fiber bundle having an area density of 20 g / m ² and a thickness of 100 μm ( Average fineness 6.
4 μg / m, average fiber diameter 0.25 μm, melting point 166 ° C.)
And polyethylene ultrafine fiber bundle (average fineness 6.4 μg / m,
A fiber web (average fiber diameter of 0.225 μm) was formed in a mixed state with an average fiber diameter of 0.2 μm and a melting point of 128 ° C.

The fiber web in which the ultrafine fiber bundle of polypropylene and the ultrafine fiber bundle of polyethylene is entangled is placed on an iron plate having a thickness of 10 mm in a perch, and an electric wire located 5 mm above the iron plate. An ultrasonic wave having a frequency of 19.5 kHz and an amplitude of 50 μm is transmitted from a distorted ultrasonic horn.
Irradiation was performed for 2 seconds to obtain a nonwoven fabric in which polypropylene ultrafine fibers having an average fiber diameter of 0.25 μm and polyethylene ultrafine fibers having an average fiber diameter of 0.2 μm were uniformly dispersed.

Next, this nonwoven fabric was subjected to a Shore B hardness of 80.
1.5 kN / c linear pressure between resin roll and metal roll
m at a speed of 10 m / min, and a surface density of 20 g /
m ² , a non-woven fabric having an average pore diameter of 0.16 μm and an air permeability of 40 sec / 100 ml in which polypropylene microfine fibers having an average fiber diameter of 0.25 μm and polyethylene microfine fibers having an average fiber diameter of 0.2 μm having a thickness of 50 μm are uniformly dispersed Obtained.

Next, this nonwoven fabric is sandwiched between smooth glass plates so as not to cause surface shrinkage upon heating, and heat-treated in an oven at 130 ° C. for 30 minutes to partially fuse only the polyethylene ultrafine fibers. , Average pore size 0.13 μm,
A nonwoven fabric having an air permeability of 180 sec / 100 ml was obtained.

Example 3 A dried polylactic acid-based copolymer (molar ratio: L-lactic acid: D-lactic acid = 95: 5) and high-density polyethylene (MI = 6) were mixed at a weight ratio of 6: 4. (B resin component unit), a system in which polybutylene succinate and polypropylene (MI = 65) are dry blended at a mass ratio of 6: 4.
Melt spinning is performed at a spinning temperature of 240 ° C., and a fan-shaped B resin component unit in which polypropylene is uniformly dispersed is divided into eight by a fan-shaped A resin component unit in which high-density polyethylene is uniformly dispersed. Thus, a yarn having a fineness of 0.89 mg / m having a cross section similar to that of FIG. 1 (e) was obtained. The volume ratio of the A resin component unit and the B resin component unit constituting this yarn was 1: 1. Next, the yarn was drawn in a warm bath at 90 ° C. to a fineness of 220 μg / m, and then cut into 10 mm to form a conjugate fiber.

Next, 100% of the composite fiber is used,
A fiber web having an areal density of 50 g / m ² was formed by a wet papermaking method. Next, this fiber web was heat-treated in an oven at 125 ° C. and fused with the polybutylene succinate component of the conjugate fiber, and then placed on a net (0.14 mm in wire diameter) with an opening of 0.147 mm, A cycle of discharging a water flow at a pressure of 11.8 MPa from a nozzle plate having a nozzle having a diameter of 0.13 mm and a pitch of 0.6 mm, inverting the same, and discharging a water flow at a pressure of 11.8 MPa from a similar nozzle plate is defined as one cycle. The composite fiber was divided at the same time as being entangled by two-cycle treatment, and fine fibers were generated to form an entangled fiber web. The average fiber diameter of the fibers constituting the entangled fiber web was 4 μm.

Next, the entangled fiber web is heated to a temperature of 80
The polylactic acid-based copolymer and the polybutylene succinate were decomposed and extracted by immersing in a 14 mass% aqueous sodium hydroxide solution at 20 ° C. for 20 minutes, and a polypropylene ultrafine fiber bundle having an area density of 20 g / m ² and a thickness of 100 μm ( Average fineness 5.8 μg / m, average fiber diameter 0.4 μm, melting point 166
° C) and a polyethylene ultrafine fiber bundle (average fineness 5.8 μg /
m, average fiber diameter 0.4 μm, melting point 128 ° C.) to form a fiber web (average fiber diameter 0.4 μm).

The fiber web in which the ultrafine fiber bundle of polypropylene and the ultrafine fiber bundle of polyethylene is entangled is placed on a 10 mm-thick iron plate in a perch, and an electric wire located 5 mm above the iron plate. An ultrasonic wave having a frequency of 19.5 kHz and an amplitude of 50 μm is transmitted from a distorted ultrasonic horn.
Irradiation was performed for 2 seconds to obtain a nonwoven fabric in which ultrafine polypropylene fibers having an average fiber diameter of 0.4 μm and ultrafine polyethylene fibers having an average fiber diameter of 0.4 μm were uniformly dispersed.

Next, this nonwoven fabric was subjected to a Shore B hardness of 80.
1.5 kN / c linear pressure between resin roll and metal roll
m at a speed of 10 m / min, and a surface density of 20 g /
m ² , a polypropylene microfiber having a thickness of 50 μm and an average fiber diameter of 0.4 μm and a polyethylene microfiber having an average fiber diameter of 0.4 μm are uniformly dispersed. The average pore diameter is 0.32 μm and the air permeability is 1.
A non-woven fabric of 3 sec / 100 ml was obtained.

Next, this nonwoven fabric is sandwiched between smooth glass plates so as not to cause surface shrinkage upon heating, and heat-treated in an oven at 130 ° C. for 30 minutes to partially fuse only the polyethylene ultrafine fibers. A nonwoven fabric having an average pore size of 0.2 μm and an air permeability of 25 sec / 100 ml was obtained.

[0053]

The composite fiber which can be made into a fine fiber according to the present invention is composed of two or more types of biodegradable polymer components including a crystalline biodegradable polymer component. As a result, a different type of biodegradable polymer component is substantially divided into two or more, and in at least one biodegradable polymer component, the biodegradable polymer component remover is difficult to remove. Contains polymer components.

Therefore, even if the biodegradable polymer component of the composite fiber which can be made into a fine fiber is removed and the removed material is left in the natural world or discarded, it does not decompose and destroy the environment. It is a conjugate fiber that can be processed into fine fibers.
Further, the conjugate fiber which can be made into a fine fiber of the present invention can be divided between the biodegradable polymer components. Fine fibers composed of coalesced components are fine, even if the fine fibers are bundled, since the fine fibers can be more easily dispersed because they are finer than the bundle of fine fibers obtained from conventional sea-island fibers. The use of the composite fiber capable of being made into a fine fiber of the present invention makes it possible to form a uniform fiber sheet having a smaller pore size.

[Brief description of the drawings]

FIG. 1A is a schematic cross-sectional view of an example of the conjugate fiber of the present invention which can be made into a fine fiber. FIG. 1B is a schematic cross-sectional view of another example of the conjugate fiber of the present invention which can be made into a fine fiber. (D) A schematic cross-sectional view of another example of the conjugate fiber capable of forming a fine fiber according to the present invention. (E) A conjugate fiber capable of forming a fine fiber of the present invention. Schematic sectional view of another example of

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Amorphous biodegradable polymer component 2 Crystalline biodegradable polymer component 3 Permanently removable polymer component 4 Permanently removable polymer component

Claims (7)

[Claims] Claims: 1. A crystalline biodegradable polymer component comprising:
It is composed of at least one kind of biodegradable polymer component, and the same kind of biodegradable polymer component substantially divides different types of biodegradable polymer components into two or more. A composite fiber capable of being made into fine fibers, characterized in that the coalesced component contains a polymer component that is difficult to remove as a remover for the biodegradable polymer component. 2. The biodegradable polymer component comprises a combination of a lactic acid-based copolymer and an aliphatic polyester-based polymer and / or an aliphatic polyesteramide-based copolymer. The conjugate fiber according to 1, which can be made into a fine fiber. 3. The composite fiber according to claim 1, wherein the hardly removable polymer component is dispersed in an island shape. 4. The method according to claim 1, wherein the hard-to-removable polymer component contained in one biodegradable polymer component comprises only the same type of polymer component. The conjugate fiber which can be made into a fine fiber according to the above. 5. Two or more types of hard-to-removable polymer components including a hard-to-removable polymer component having a melting point difference of 10 ° C. or more from different hard-to-removable polymer components. The conjugate fiber according to any one of claims 1 to 4, comprising a polymer component of 6. The hard-to-remove polymer component comprises only a polyolefin-based resin component.
The conjugate fiber capable of being made into a fine fiber according to claim 5. 7. The composite capable of forming a fine fiber according to claim 1, comprising at least a polyethylene component and a polypropylene component as the hardly removable polymer component. fiber.