JP3487722B2 - Composite fibers that can be made into fine fibers - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, composite fibers generally known as sea-island fibers have been known. This sea-island fiber is one in which one polymer component is dispersed in an island shape in another polymer component (resultingly in a sea-like shape) in the fiber cross section. By extracting and removing the sea-like polymer component, By generating thin fibers composed of island-shaped polymer components or extracting and removing island-shaped polymer components, it is possible to form porous fibers composed only of sea-shaped polymer components. In the case of (1), it has been used for various purposes, mainly for artificial leather, and in the case of the latter, mainly for filtration and liquid retention.

However, each of the sea-like polymer component and / or the island-like polymer component constituting the sea-island fiber is a synthetic polymer such as polyamide, polyester, polyolefin, or polystyrene which is hardly decomposed in the natural world. Therefore, the solvent from which the synthetic polymer was extracted was recovered,
Had to handle. However, much effort was required to recover and treat the solvent from which this synthetic polymer was extracted.

Further, after forming a fiber sheet such as a non-woven fabric using this sea-island fiber, the sea-like polymer component of the sea-island fiber is extracted and removed to obtain a thin fiber composed of the island-like polymer component. Although a method of forming a fiber sheet composed is known, the fiber sheet formed by such a method is
No matter what method is used, the application may be limited due to the large pore size of the fiber sheet.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to form a fiber sheet having a small pore size, which is easy to process the polymer component removed from the fiber. It is an object of the present invention to provide a composite fiber that can be obtained.

[0006]

Means for Solving the Problems The finely fibrillar composite fiber of the present invention (hereinafter simply referred to as “composite fiber”) is a crystalline biodegradable polymer component (hereinafter referred to as “crystalline component”).
Including, made of two or more biodegradable polymer component, the biodegradable polymer component of the same kind, it is substantially divided biodegradable polymer component of different kinds into two or more, even deer, these raw
The degradable polymer component is composed of a lactic acid-based copolymer and an aliphatic polyester.
Stell polymer and / or aliphatic polyester amide
A polymer component which is composed of a combination with a copolymer and is difficult to remove as a removing agent for the biodegradable polymer component in all of these biodegradable polymer components (hereinafter referred to as "difficulty-removable component"). together contain these, the respective flame removability heavy
Difficult-to-remove polymerization where the combined components have a melting point difference of 10 ° C or more
Contains two or more body components.

Therefore, even if the biodegradable polymer component of the conjugate fiber is removed and the removed product is left in nature or discarded, it does not decompose and does not damage the environment. Is. Further, the conjugate fiber of the present invention can be split between biodegradable polymer components, and after splitting,
Obtained by removing this biodegradable polymer component, the fine fibers composed of the hard-to-removable component are thin, and even if the fine fibers are in a bundle, since even thin, as possible out to be more easily dispersed fine fibers. Therefore, when the conjugate fiber of the present invention is used, it is possible to form a uniform fiber sheet having a smaller pore size , and moreover, a different difficult-to-remove component of 10 ° C.
By including the hard-to-remove component having the above melting point difference,
It is possible to improve the strength of the fiber sheet.

[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 at the same time, a fiber sheet containing the conjugate fiber or a fine fiber generated from the conjugate fiber. The fiber sheet containing is also excellent in strength.

The crystallinity of the crystalline component means, for example, a glass transition temperature, a crystallization temperature and a melting temperature in a thermal analysis method such as a differential scanning calorimeter (DSC). This crystalline component is not particularly limited,
For example, an aliphatic polyester polymer, an aliphatic polyesteramide copolymer, or D-lactic acid of 0.05 to 30 is used.
It is possible to use a lactic acid-based copolymer or the like in which mol% copolymerization or L-lactic acid is 0.05 to 30 mol% copolymerization. Among these crystalline components, the aliphatic polyester-based polymer and the aliphatic polyesteramide-based copolymer are thermoplastic and can act as an adhesive component before splitting to generate fine fibers or after generating fine fibers. Therefore, it can be preferably used. Moreover, since the lactic acid-based copolymer has excellent heat resistance, it can be preferably 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, and by neutralizing the solution hydrolyzed with an alkaline solution with an acid, it is possible to treat with activated sludge, which is environmentally friendly. 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. Copolymer or copolymer, 3-hydroxypropionate, 3
-Hydroxybutyrate, 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxyvalerate, polymers or copolymers of β-hydroxyalkanoates such as 4-hydroxybutyrate, polyethylene oxalate, polyethylene Condensation polymer of diol and dicarboxylic acid such as succinate, polyethylene adipate, polyethylene azelate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, polybutylene sebacate, polyhexamethylene sebacate, polyneopentyl oxalate. Or, there are copolymers, etc., as the aliphatic polyester amide-based copolymer, to the above aliphatic polyester-based polymer, capramide,
There are copolymers of aliphatic amides such as tetramethylene adipamide, undecanamide, laurolactamide and hexamethylene adipamide. Among them, aliphatic polyester-based polycondensation polymers or copolymers of diols and dicarboxylic acids, especially polyethylene succinate and polybutylene succinate are excellent in spinnability and are therefore suitable crystalline components.

Examples of lactic acid-based copolymers include:
Examples thereof include copolymers of D-lactic acid and L-lactic acid, copolymers of D-lactic acid and hydroxycarboxylic acid, and copolymers of L-lactic acid and hydroxycarboxylic acid. 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 preferably used.

The aliphatic polyester polymer and /
Alternatively, a combination of an aliphatic polyesteramide-based copolymer and a lactic acid-based copolymer is a preferable combination because the crystalline components are likely to be divided to generate fine fibers. 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. It is a combination.

The composite fiber of the present invention is composed of two or more kinds of biodegradable polymer components containing the above-mentioned crystalline component. This combination may be composed of only two or more kinds of crystalline components, or may contain an amorphous biodegradable polymer component (hereinafter referred to as "amorphous component"). When the former is composed only of crystalline components, the composite fiber itself is excellent in strength, and the fiber sheet containing this composite fiber or the fiber sheet containing fine fibers generated from the composite fiber is also excellent in strength, and the latter non- If it also contains a crystalline component, it is more excellent in biodegradability.

The amorphous property of the amorphous component means, for example, in a thermal analysis method such as a differential scanning calorimeter (DSC), a glass transition temperature is shown but a crystallization temperature and a melting temperature are not shown. As this amorphous component, for example, D
-Copolymerization of lactic acid from 30.05 to 69.95 mol%, or L-
There is a lactic acid-based copolymer in which lactic acid is copolymerized in an amount of 30.05 to 69.95 mol%. More specifically, there are copolymers of D-lactic acid and L-lactic acid, copolymers of D-lactic acid and hydroxycarboxylic acid, copolymers of L-lactic acid and hydroxycarboxylic acid, and the like. Among them, those obtained by copolymerizing D-lactic acid and L-lactic acid in a molar ratio of 30.05: 69.95 to 69.95: 30.05 are more excellent in biodegradability and can be suitably used. This amorphous lactic acid-based copolymer is preferable because it is likely to be divided into fine fibers when combined with the above-mentioned crystalline component aliphatic polyester-based polymer or aliphatic polyesteramide-based copolymer. It is a combination. Therefore, polyethylene succinate and / or polybutylene succinate, and D-lactic acid and L-lactic acid are 3
A preferred combination is a combination with those copolymerized at a molar ratio of 0.05: 69.95 to 69.95: 30.05.

The composite fiber of the present invention is composed of two or more kinds of biodegradable polymer components containing a crystalline component, and more than two different biodegradable polymer components by the same kind of biodegradable polymer component. Since the biodegradable polymer components are substantially divided into, the biodegradable polymer components can be separated and separated.

The same type of biodegradable polymer component means that the side-by-side type composite fiber is spun from a target resin and then the side-by-side type composite fiber is stretched with a finger to apply a shearing force to form two fibers. It is a substance that is difficult to split. Different types of biodegradable polymer components are two fibers produced by spinning the side-by-side type composite fiber from the target resin, then stretching this side-by-side type composite fiber with a finger and applying a shearing force. It can be divided into other fibers.

The divided state is that the crystalline component and / or the amorphous component is roughly divided by the crystalline component, and the crystalline component and / or the amorphous component is substantially divided by the amorphous component. There is.

Then, in all biodegradable polymer components,
The biodegradable polymer component remover contains a difficult-to-remove component. Therefore, after dividing between the biodegradable polymer components, if the biodegradable polymer is removed, it is possible to generate fine fibers composed of a difficult-to-remove component, and fine fibers composed of the difficult-to-remove component are Since it is obtained by removing the biodegradable polymer component after being divided, it is in the form of a bundle, but it is thinner than a bundle of conventional fine fibers, and the fine fibers can be easily dispersed. Therefore, it is possible to form a uniform sheet having a smaller pore size.

As the removing agent for the biodegradable polymer component, there are solvents, enzymes, microorganisms and the like. Among them, the solvent has a high removal rate and is easy to handle, and therefore can be preferably used. Among these solvents, water-based ones are suitable for production because they are easier to handle and process, and an alkali solution that can easily extract the biodegradable polymer component can be most preferably used. In the case of removing with this alkaline solution, the environment is not damaged if it is neutralized with an acid solution and discarded after extraction.

The term "difficulty removing property" means that the removal rate of the biodegradable polymer component to be removed is ½ or less, and the difficult removal component varies depending on the remover of the biodegradable polymer component. However, for example, when the biodegradable polymer component is removed with a suitable alkaline solution, as a difficult-to-remove component, polyolefin such as polyethylene, polypropylene, polystyrene, nylon 11, nylon 12, nylon 6, nylon 6,
One or more of nylon 66 such as nylon 66 and modified nylon, polyester such as polyester and modified polyester, ester elastomer, olefin elastomer and urethane elastomer can be used. Among these, polyolefin resin is excellent in alkali resistance and hardly loses mass, so that it can be preferably used.

[0021] Incidentally, in the composite fibers of the present invention, having a melting point difference of 10 ° C. or more as a flame removal component, by including two or more flame removal components, flame removability having the highest melting point The difficult-to- remove components other than the components are fused . this
Therefore, it is possible to improve the strength of the fiber sheet,
The hiding property can be improved by forming a film by melting . It should be noted that different kinds of difficult-to-remove components are judged based on their melting points.

Further, it is more preferable that the hardly-removable component is composed of only the polyolefin resin component, because it has excellent chemical resistance and can be adapted to various uses. In particular,
If polypropylene is included as the polyolefin-based resin component, the separation performance can be improved by making it into an electret, and therefore it can be preferably used. Also,
In the case of containing polypropylene, it can be fused without adversely affecting the polypropylene so that the strength of the fiber sheet can be improved and / or the hiding property can be improved. It preferably comprises a density polyethylene.

The composite fiber of the present invention will be described below with reference to FIG. It should be noted that FIG. 1 shows a composite fiber in which one type of crystalline component is divided by one type of amorphous component, but a composite fiber composed of only two or more types of crystalline components,
The same split state also in the case of a composite fiber composed of two types of amorphous components and two or more crystalline components, or a composite fiber composed of two or more types of amorphous components and one or more crystalline components If it is good.

FIG. 1 (a) shows a composite fiber in which the crystalline component 2 is divided into two by the amorphous component 1 and the hard-to-remove component is contained in any of the biodegradable polymer components. , This composite fiber is divided into one fiber containing the amorphous component 1 as the sea component and two fibers containing the crystalline component 2 as the sea component, and then the amorphous component 1 and the crystalline component 2 are separated. If removed, fine fibers composed of the hard-to-remove components 3 and 4 can be generated. It is not necessary for the amorphous component 1 to divide the crystalline component 2 into two parts. If the crystalline component 2 is divided into three or more parts as shown in FIGS. Since the fibers generated in this manner are finer and the fine fiber bundle composed of the hard-to-remove component obtained by removing the biodegradable polymer component of the generated fiber is smaller, it is preferable. Preferably, the average fiber diameter of the fiber before removal of the biodegradable polymer component is divided into four or more (in the case of a fiber having an irregular cross-sectional shape, a value converted into a circular cross-section),
20 μm or less, preferably 10 μm or less, more preferably 6 μm
It is preferable to design so as to be m or less.

The average fiber diameter of the fine fibers composed of the hard-to-remove component obtained by removing the biodegradable polymer component is 3 μm.
It is preferably below, more preferably below 2 μm, most preferably below 1 μm. If the number of fine fibers composed of the hard-to-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. 500 or more fine fibers composed of, more preferably 2,000
It is preferable that the hard-to-remove component is dispersed in an island shape so that 0 or more can be generated. The fine fibers composed of the hard-to-remove component are preferably uniformly dispersed in the biodegradable polymer component, but they may be partially distributed. Further, the cross-sectional shape of the fine fibers composed of the hard-to-remove component does not have to be circular, and may be elliptical, elliptical, polygonal, or the like, and is not particularly limited.

[0026] The flame is removed component, by being included in the biodegradable polymer component of the whole hand, it is possible to reduce the amount of biodegradable component divided, yet high fiber density fiber Ru it is possible to obtain a sheet. Contact name hardly removed components are contained in one biodegradable polymer component, but need not one, but two or more kinds of flame removed components may be mixed, each biodegradable When the polymer component your capital to free Murrell flame removal component consists only of the polymer component of the same type, when that caused the fine fibers made of flame removed components, densely fine fibers consisting of poorly removed components of the same type To do. Therefore, by melting this fine fiber or by melting it in the external environment, it is possible to impart various properties such as making the pore size of the fiber sheet more uniform and partially changing the degree of hydrophilicity. It is suitable.

Incidentally, the division by the amorphous component 1 is preferable because the amorphous component 1 is exposed on the fiber surface and completely divided, because fine fibers are more likely to be generated, but the amorphous component 1 is preferable. It is not necessary that the component 1 is exposed to the fiber surface and is completely divided, and if it is almost divided, that is, if the end of the amorphous component 1 is within 5 μm from the fiber surface, the difficult-to-remove component is It can be divided into fibers comprising a biodegradable polymer component containing. It is preferable that the amorphous component 1 has a linear cross-sectional shape because it is more easily divided and fine fibers are easily generated. However, the amorphous component 1 has a curved shape or a fan shape as shown in FIG. Is also good. As shown in FIG. 1 (e), when the amorphous component 1 has a fan-shaped cross-section, the size of all the fibers made of the biodegradable polymer component including the hardly-removable component is almost the same. It is possible to obtain a more uniform fiber sheet, because the fine fibers composed of the hard-to-remove component obtained by removing the biodegradable polymer component of this fiber consist of fiber bundles of the same size. Is preferred. The cross-sectional shape of the composite fiber does not have to be circular, and may be elliptical, oval, polygonal, or the like, and is not particularly limited.

Such a conjugate fiber can be obtained by appropriately combining the usual conjugate spinning method and / or mixing spinning method,
It can be easily spun. For example, the composite fiber having the cross-sectional shape illustrated in FIG. 1 (e) is formed by extruding a mixed melt of an amorphous component and a hard-to-remove component from the small pores, and between the small pores extruding the mixed melt. It can be obtained by extruding a mixed melt of a crystalline component and a hard-to-remove component from the small holes, then compounding and stretching.

Using the conjugate fiber of the present invention as described above, a woven fabric, a knitted fabric, a non-woven fabric or the like is formed, and then the conjugate fiber is divided to generate fine fibers, or the conjugate fiber is divided to form fine fibers. A fiber sheet having a small pore size and excellent uniformity can be formed by forming the fiber sheet after the generation.

A fiber sheet using the conjugate fiber of the present invention contains fine fibers composed of a hard-to-remove component, has a small pore size and is excellent in uniformity. Suitable for a variety of applications such as base fabrics, masks, medical protective materials, battery separators, air-conditioning or liquid filters, synthetic or artificial leather substrates, outer garment materials, interior materials, cleaning materials, liquid retention materials, etc. it can. It should be noted that the fiber sheet is dyed, raised, laminated, molded,
By embossing or chemically or physically surface-treating, various functions can be added to suit various uses.

Examples of the present invention will be described below, but the invention is not limited to the following examples. The melting point, average pore size, air permeability, etc. shown in the examples were determined by the following methods.

Melting point: Using a differential scanning calorimeter (manufactured by Mac Science Co., Ltd., DSC-3100 type), a heating rate of 10
The melting point was measured at the condition of ° C / min, and the melting point was the temperature at which the exothermic value was the extreme value.

Average Pore Size: Mercury Porosimeter (CARL
O ERBA STRUMENTAZIONE P
It was measured by mercury porosimetry using OROSIMETER 2000).

Air permeability: According to JIS P8117, the non-woven fabric is made into a standard Gurley Densometer (Gurley Den
The measurement was carried out by mounting it on a meter. That is, 64
The average number of seconds required for 100 ml of air to pass through a nonwoven 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) in a mass ratio of 6: 4. Mass ratio of the prepared system (A resin component unit), polybutylene succinate and polypropylene (MI = 65):
Using a system (B resin component unit) dry-blended in 4, melt-spun 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-shaped B resin component unit in which polypropylene was uniformly dispersed was divided into eight, and a yarn having a fineness of 0.89 mg / m having a cross-sectional shape 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, this yarn was drawn in a warm bath at 90 ° C. to have a fineness of 220 μg / m, and then cut into 10 mm to form a composite fiber.

Then, using 100% of this composite fiber,
A fiber web having an areal density of 50 g / m ² was formed by a wet papermaking method. Then, the fiber web was heat-treated in an oven at 125 ° C., fused with the polybutylene succinate component of the composite fiber, and then placed on a net having an opening of 0.147 mm (wire diameter 0.14 mm), A nozzle plate having nozzles with a diameter of 0.13 mm and a pitch of 0.6 mm ejects a water flow having a pressure of 11.8 MPa and inverts it, and ejects a water flow having a pressure of 11.8 MPa from the same nozzle plate as one cycle. The entangled fiber web was formed by performing two cycles of treatment to split the composite fibers at the same time as they were entangled to generate fine fibers. The average fiber diameter of the fibers constituting this entangled fiber web was 4 μm.

The entangled fibrous web is then heated to a temperature of 80.
The polylactic acid copolymer and polybutylene succinate were decomposed and extracted by immersing in a 14 mass% aqueous sodium hydroxide solution at 20 ° C. for 20 minutes to obtain a polypropylene ultrafine fiber bundle having an area density of 20 g / m ² and a thickness of 100 μm ( Average fineness 5.
Fiber web (average) of 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.) Fiber diameter 0.3 μm) was formed.

Then, the fiber web in which the polypropylene ultrafine fiber bundle and the polyethylene ultrafine fiber bundle are entangled is placed on an iron plate having a thickness of 10 mm in the perkren, and the electric wire is placed 5 mm above the iron plate. 1 ultrasonic wave with a frequency of 19.5 kHz and an amplitude of 50 μm from a strain type ultrasonic horn
Irradiation for 2 seconds gave 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 non-woven fabric is subjected to Shore B hardness of 80.
Line pressure between the resin roll and the metal roll is 1.5 kN / c
m at a speed of 10 m / min and an areal density of 20 g /
m ² , thickness 50 μm, average fiber diameter 0.4 μm polypropylene ultrafine fibers and average fiber diameter 0.2 μm polyethylene ultrafine fibers were uniformly dispersed, average pore diameter 0.20 μm, air permeability 2
A non-woven fabric of 5 sec / 100 ml was obtained.

Next, this non-woven fabric was 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 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 in a mass ratio of 6: 4. Using a system (A resin component unit) dry-blended with B and a system (B resin component unit) dry-blended with polybutylene succinate and polypropylene (MI = 124) at a mass ratio of 6: 4, Melt spinning at 240 ℃,
A fan-shaped A resin component unit in which high-density polyethylene is uniformly dispersed has eight fan-shaped B resin component units in which polypropylene is uniformly dispersed, and has a cross-sectional shape similar to that of FIG. A yarn having 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. Then, this thread 90
After stretching in a warm bath at ℃ to a fineness of 240 μg / m, 1
It was cut to 0 mm to form a composite fiber.

Next, using 100% of this composite fiber,
A fiber web having an areal density of 50 g / m ² was formed by a wet papermaking method. Then, the fiber web was heat-treated in an oven at 125 ° C., fused with the polybutylene succinate component of the composite fiber, and then placed on a net having an opening of 0.147 mm (wire diameter 0.14 mm), A nozzle plate having nozzles with a diameter of 0.13 mm and a pitch of 0.6 mm ejects a water flow having a pressure of 11.8 MPa and inverts it, and ejects a water flow having a pressure of 11.8 MPa from the same nozzle plate as one cycle. The entangled fiber web was formed by performing two cycles of treatment to split the composite fibers at the same time as they were entangled to generate fine fibers. The average fiber diameter of the fibers constituting this entangled fiber web was 4.2 μm.

The entangled fibrous web is then heated to a temperature of 80.
The polylactic acid copolymer and polybutylene succinate were decomposed and extracted by immersing in a 14 mass% aqueous sodium hydroxide solution at 20 ° C. for 20 minutes to obtain 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 fibrous web (average fiber diameter 0.225 μm) in a mixed state with an average fiber diameter 0.2 μm and a melting point of 128 ° C. was formed.

The fiber web in which the polypropylene ultrafine fiber bundles and the polyethylene ultrafine fiber bundles are entangled is placed on an iron plate having a thickness of 10 mm in the perkren, and the electric wire is placed 5 mm above the iron plate. 1 ultrasonic wave with a frequency of 19.5 kHz and an amplitude of 50 μm from a strain type ultrasonic horn
Irradiation for 2 seconds gave 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 non-woven fabric is subjected to Shore B hardness of 80.
Line pressure between the resin roll and the metal roll is 1.5 kN / c
m at a speed of 10 m / min and an areal density of 20 g /
m ^2, average fiber diameter of polypropylene microfine fibers having an average fiber diameter 0.25μm thick 50μm there is 0.2μm polyethylene ultrafine fiber was uniformly dispersed, the average pore diameter 0.16 [mu] m, the nonwoven fabric and air permeability of 40 sec / 100 ml Obtained.

Next, this non-woven fabric was 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 polyethylene ultrafine fibers. , Average pore diameter 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 in a mass ratio of 6: 4. Dry-blended system (A resin component unit) and polybutylene succinate and polypropylene (MI = 65) were dry-blended in a mass ratio of 6: 4 (B resin component unit)
And was melt-spun at a spinning temperature of 240 ° C., and a fan-shaped A resin component unit in which high-density polyethylene was uniformly dispersed was divided into eight fan-shaped B resin component units in which polypropylene was uniformly dispersed. Thus, a yarn having a fineness of 0.89 mg / m having a cross-sectional shape 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, this yarn was drawn in a warm bath at 90 ° C. to have a fineness of 220 μg / m, and then cut into 10 mm to form a composite fiber.

Then, using 100% of this composite fiber,
A fiber web having an areal density of 50 g / m ² was formed by a wet papermaking method. Then, the fiber web was heat-treated in an oven at 125 ° C., fused with the polybutylene succinate component of the composite fiber, and then placed on a net having an opening of 0.147 mm (wire diameter 0.14 mm), A nozzle plate having nozzles with a diameter of 0.13 mm and a pitch of 0.6 mm ejects a water flow having a pressure of 11.8 MPa and inverts it, and ejects a water flow having a pressure of 11.8 MPa from the same nozzle plate as one cycle. The entangled fiber web was formed by performing two cycles of treatment to split the composite fibers at the same time as they were entangled to generate fine fibers. The average fiber diameter of the fibers constituting this entangled fiber web was 4 μm.

The entangled fibrous web is then heated to a temperature of 80.
The polylactic acid copolymer and polybutylene succinate were decomposed and extracted by immersing in a 14 mass% aqueous sodium hydroxide solution at 20 ° C. for 20 minutes to obtain 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
℃) and polyethylene ultrafine fiber bundle (average fineness 5.8 μg /
m, average fiber diameter 0.4 μm, melting point 128 ° C.) to form a fibrous web (average fiber diameter 0.4 μm).

Then, the fiber web in which the polypropylene ultrafine fiber bundle and the polyethylene ultrafine fiber bundle are entangled is placed on an iron plate having a thickness of 10 mm in a perkren, and an electric wire located 5 mm above the iron plate is placed. 1 ultrasonic wave with a frequency of 19.5 kHz and an amplitude of 50 μm from a strain type ultrasonic horn
Irradiation for 2 seconds gave 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 0.4 μm were uniformly dispersed.

Then, this non-woven fabric was subjected to Shore B hardness of 80.
Line pressure between the resin roll and the metal roll is 1.5 kN / c
m at a speed of 10 m / min and an areal density of 20 g /
m ^{2 with} a thickness of 50 μm, polypropylene ultrafine fibers with an average fiber diameter of 0.4 μm and polyethylene ultrafine fibers with an average fiber diameter of 0.4 μm, average pore diameter 0.32 μm, air permeability 1
A non-woven fabric of 3 sec / 100 ml was obtained.

Next, this non-woven fabric was 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 polyethylene ultrafine fibers. A non-woven fabric having an average pore diameter of 0.2 μm and an air permeability of 25 sec / 100 ml was obtained.

[0053]

EFFECTS OF THE INVENTION The finely fibrillated composite fiber of the present invention comprises two or more biodegradable polymer components containing a crystalline biodegradable polymer component , that is, a lactic acid-based copolymer and a fat. Tribe polies
Ter polymer and / or aliphatic polyester amide copolymer
A biodegradable polymer component of the same kind is substantially divided into two or more different biodegradable polymer components, and all of these biodegradable polymer components are combined. It is difficult to remove the biodegradable polymer component in the combined component , and the melting point is 10 ° C or more.
It contains two or more polymer components having a difference .

Therefore, even if the biodegradable polymer component of the fine fiber that can be made into fine fibers is removed and the removed product is left in nature or discarded, it will not be decomposed and will not destroy the environment. It is a composite fiber that can be easily processed into fine fibers.
Further, the finely fibrillar conjugate fiber of the present invention can be divided between biodegradable polymer components, and a hard-to-removable polymer obtained by removing the biodegradable polymer component after the division. The fine fibers composed of the coalesced component are thin, and even if the fine fibers are bundled, they are thinner than the bundle of fine fibers obtained from the conventional sea-island fiber, and therefore the fine fibers can be more easily dispersed . Therefore, by using the finely fibrillated composite fiber of the present invention, the pore diameter is smaller and uniform , and
Also, strength improvement and film formation by fusion using difference in melting point
It is possible to form a fiber sheet aiming at

[Brief description of drawings]

FIG. 1 (a) is a schematic cross-sectional view of an example of a fine fiber-forming conjugate fiber of the present invention (b) is a schematic cross-sectional view of another example of a fine fiber-forming composite fiber of the present invention (c). (D) A schematic cross-sectional view of another example of the fine fiber-convertible conjugate fiber of (d) A schematic cross-sectional view of another example of the fine fiber-convertible conjugate fiber of the present invention (e) Schematic cross-sectional view of another example

[Explanation of symbols]

1 Amorphous biodegradable polymer component 2 Crystalline biodegradable polymer component 3 Difficult-to-remove polymer component 4 Difficult-to-remove polymer component

Continuation of front page (51) Int.Cl. ⁷ Identification code FI // D06M 101: 32 D06M 101: 32

Claims (5)

(57) [Claims] 1. A composition comprising a crystalline biodegradable polymer component, 2
It consists or more biodegradable polymer component, the biodegradable polymer component of the same kind, the biodegradable polymer component of the heterogeneous are substantially divided into two or more, even deer, biodegradable polymer Success
Lactic acid-based copolymer and aliphatic polyester-based polymer
And / or a combination with an aliphatic polyesteramide-based copolymer
The biodegradable polymer component contains a difficult-to-remove polymer component as a remover for the biodegradable polymer component , and these hard-to-remove polymer components are contained in all of these biodegradable polymer components.
Is a difficult-to-remove polymer component having a melting point difference of 10 ° C. or higher.
A composite fiber that can be made into fine fibers, characterized by containing two or more kinds . 2. The finely fibrillar composite fiber according to claim 1, wherein the hardly removable polymer component is dispersed in an island shape. Of 3. A flame removability included in one biodegradable polymer component in the polymer component, characterized by comprising the only polymer component of the same kind, according to claim 1 or claim 2 A composite fiber that can be made into fine fibers. 4. A polymer component of the flame removability is characterized in that it consists of only the polyolefin resin component, fine fiberizable composite fiber according to any one of claims 1 to 3. As 5. The polymer component of the flame removability, characterized in that it contains at least a polyethylene component and a polypropylene component, which can be fine fiberization according to any one of claims 1 to 3 Composite fiber.