JP2000328367A - Polyolefin-based splittable composite fiber and fiber molded article using the same - Google Patents

Abstract

(57) [Summary] [Problem] To provide a polyolefin-based splittable conjugate fiber which is easy to split without adding any additive for improving splittability, and a dense and well-formed fiber molded article using the same. To do. (1) The fiber is composed of at least two components of a polyolefin resin, and in a fiber cross section, each component is alternately arranged in a radial pattern, and has a hollow portion in the center of the fiber. Is 5 to 40%, and the ratio (W / L) of the average length W of the fiber outer peripheral arc and the average thickness L from the hollow portion to the fiber outer peripheral portion of one resin component is 0.25 to 2.5.
A polyolefin-based splittable conjugate fiber, and (2)
The polyolefin-based splittable conjugate fiber is at least 3
0% by weight or more, and the splittable conjugate fiber is split into 50% or more to obtain a fiber molded body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin splittable conjugate fiber having excellent splittability. More specifically, a polyolefin-based splittable conjugate fiber having excellent splitting properties, which can be suitably used in the field of industrial materials such as battery separators, wipers, and filters, and in the field of sanitary materials such as diapers and napkins. The present invention relates to a fiber molded body used.

[0002]

2. Description of the Related Art Conventionally, as a method for obtaining ultrafine fibers, it has been known to use sea-island type or split type composite fibers. In the method using sea-island composite fibers, a plurality of components are combined and spun into sea-island composite fibers, and one component of the obtained composite fibers is dissolved and removed to obtain ultrafine fibers. Although this method can obtain very fine fibers, it is uneconomical to dissolve and remove one component. On the other hand, the method of using the splittable conjugate fiber is a method in which a resin of a plurality of components is combined and spun to form a conjugate fiber. Utilizing the splittable conjugate fiber into a large number of fibers to obtain ultrafine fibers.

For example, splittable conjugate fibers typified by a combination of a polyester resin and a polyolefin resin, a combination of a polyester resin and a polyamide resin, and a combination of a polyamide resin and a polyolefin resin are easily split by physical stress. However, the ultrafine fibers obtained by splitting and the fiber molded body made of the fibers are mixed with different types of polymers, and at present, their use in industrial materials where chemical resistance is required is limited. is there.

[0004] On the other hand, in the case of a combination of polyolefin resins having excellent chemical resistance, the compatibility of the resins is relatively good as compared with the combination of the above-mentioned different kinds of polymers. Needed to increase the physical impact. For this reason, the obtained nonwoven fabric has a so-called unevenness, such as a divided portion and a non-divided portion, and the composite fiber moves by a physical impact, and a thick portion and a thin portion are formed. It was never satisfactory because of poor formation and the need to significantly reduce the processing speed of high pressure liquid flow treatment.

In order to improve this, Japanese Patent Laid-Open No. Hei 4-2892 has been proposed.
Japanese Patent Laid-Open Publication No. 2 (1999) -2000 discloses that by adding an organosiloxane and a modified product thereof, splittable composite fibers of the same polymer can be easily split. However, although the splittability is somewhat improved, the nonwoven fabric using the split fibers has many problems such as reduced strength and poor workability at the time of secondary processing.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyolefin-based splittable conjugate fiber which can improve these drawbacks, and a fiber molded article using the same. That is, the present invention provides a polyolefin-based splittable conjugate fiber that can be easily split without using any special additives for improving splittability, and a dense and well-formed fiber molded article using the same. It is in.

The present inventors have conducted intensive studies to achieve the above object. As a result, the composite fiber is composed of at least two components of a polyolefin resin, and in the fiber cross section, each component is a conjugate fiber having hollow portions alternately arranged radially, and the hollow ratio of the hollow portions is 5 to 40%. The ratio W / L of the average length W of the fiber outer peripheral arc and the average thickness L from the hollow portion to the fiber outer peripheral portion of one resin component constituting the fiber is defined as 0.25 to 2.5. It has been found that the splittable conjugate fiber that satisfies becomes a splittable conjugate fiber that is easy to split, and that the use of the splittable conjugate fiber results in a dense and well-formed fiber molded body. Completed the invention.

[0008]

The present invention has the following arrangement to solve the above-mentioned problems. (1) A composite fiber composed of at least two components of a polyolefin-based resin, and in a fiber cross-section, each component is arranged alternately in a radial pattern and has a hollow portion in the center of the fiber. 5-40%, and the average length W of the fiber outer peripheral arc of one resin component constituting the fiber
And the ratio of the average thickness L from the hollow portion to the outer peripheral portion of the fiber (W /
L) is 0.25 to 2.5, wherein the polyolefin-based splittable conjugate fiber is characterized in that:

(2) The shape of the hollow portion in the fiber cross section is
2. The polyolefin-based splittable conjugate fiber according to claim 1, which has a shape including at least one curved portion having a radius of curvature (ρ) smaller than the radius of a circle having the same area as the hollow portion.

(3) The melt flow rate of at least two components of the polyolefin resin constituting the fiber after fiber molding is 10 to 100 g / 10 minutes, and the melting point of the polyolefin resin is the highest among the polyolefin resins. The ratio (MFR-A) of the melt flow rate (MFR-A) of the high resin component (hereinafter referred to as A component) to the melt flow rate (MFR-B) of the resin component having the lowest melting point (hereinafter referred to as B component). 3. The polyolefin splittable conjugate fiber according to any one of the above item 1 or item 2, wherein (/ MFR-B) is from 0.1 to 5.

(4) The polyolefin split type composite according to any one of the above items 1 to 3, wherein the combination of at least two components of the polyolefin resin is a combination of a polypropylene resin and a polyethylene resin. fiber.

(5) The first resin, wherein the combination of at least two components of the polyolefin resin is a combination of a stereoregular polystyrene resin and a polypropylene resin.
Item 4. The polyolefin-based splittable conjugate fiber according to any one of Items 3 to 3.

(6) The polyolefin splittable conjugate fiber according to any one of the above items 1 to 5, wherein the single-fiber fineness before splitting is 0.6 to 10 dtex and the single-fiber fineness after splitting is less than 0.6 dtex. The polyolefin-based splittable conjugate fiber according to any one of claims 1 to 7.

(7) The polyolefin splittable conjugate fiber according to any one of (1) to (6) above,
A fibrous molded article containing 0% by weight or more and 50% or more of the splittable conjugate fiber is split.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Examples of the polyolefin resin used in the polyolefin-based splittable conjugate fiber of the present invention include aliphatic α-olefins having 2 to 8 carbon atoms, such as ethylene, propylene, 1-butene, 1-pentene, and 4-methyl-1-pentene. , 3-
Olefin homopolymers such as methyl-1-butene, 1-hexene, 1-octene and the like,
Copolymers of more than one kind, these α-olefins and other olefins and / or small amounts of other ethylenically unsaturated monomers such as butadiene, isoprene, pentadiene-
Examples thereof include copolymers with ethylenically unsaturated monomers such as 1,3, styrene and α-methylstyrene, and mixtures of two or more of these. Further, examples of other olefin-based resins include stereoregular polystyrene-based resins.

[0016] The stereoregular polystyrene resin is ¹³ C
-Tacticity measured by NMR method,
Existence ratio (fraction) of a plurality of continuous structural units, for example, diat for two, triad for five,
In the case of the resin, it can be indicated by a pentad. However, as the stereoregular polystyrene resin used in the present invention, it is found at 145.35 ppm due to the syndiotactic structure from the analysis by the ¹³ C-NMR method. The syndiotacticity of the racemic pentad calculated from the area of the absorption peak indicates that the pentad fraction is 85%.
Polyalkylstyrene such as polystyrene, polymethylstyrene, polyethylstyrene, polyisopropylstyrene, and polyhalogenated styrene such as polychlorostyrene, polybromostyrene, and polyfluorostyrene having a syndiotacticity of at least 95% or more. , Polyhalogenated alkylstyrenes such as polychloromethylstyrene, polyalkoxystyrenes such as polymethoxystyrene and polyethoxystyrene, and polybenzoic acid ester styrenes. These can be used alone or in combination. Needless to say, it is a copolymer of monomers composing these polymers or a copolymer containing these monomers as a main component.

That is, at least one monomer selected from the above-mentioned monomer group, olefin monomers such as ethylene, propylene, butene, hexene, heptene, octene and decene, diene monomers such as butadiene and isoprene, and cyclic olefin monomers And copolymers having a syndiotactic styrene structure with a cyclic diene monomer or a polar vinyl monomer such as methyl methacrylate, maleic anhydride, acrylonitrile and the like. Commercial products can be used as these homopolymers or copolymers.

Typical examples of the polyolefin resin include a polypropylene resin and a polyethylene resin. Examples of the polypropylene resin include propylene homopolymer, propylene containing 70% by weight or more of propylene, and propylene. Other copolymers with the above-mentioned α-olefin, for example, ethylene-propylene copolymer, ethylene-propylene-butene copolymer and the like can be mentioned.

The polyethylene resins include high-density polyethylene (HDPE) and low-density polyethylene (L
DPE), linear low-density polyethylene (LLDPE) and the like. Among them, high-density polyethylene resin is preferable.

The melt flow rate (hereinafter abbreviated as MFR) of the polypropylene-based resin and the polyethylene-based resin among the polyolefin-based resins is not particularly limited as long as it can be spun.
/ 10 minutes is preferred, and more preferably 5 to 70 g / 1.
0 minutes.

The polyolefin-based splittable conjugate fiber of the present invention can be arbitrarily combined with a polyolefin-based resin composed of at least two components among the above-mentioned ones. When used in the field of materials and the like, a more preferable combination is a combination of two components of a polypropylene-based resin and a polyethylene-based resin, which has high chemical resistance and is advantageous in cost.

Here, any combination of the above-mentioned polyolefin-based resins is possible. For example, a combination of completely identical resins such as a polypropylene resin and a mixture of mixtures having the same composition ratio, such as a polypropylene resin, is out of the scope of the present invention. Excluded.

In the case of the combination of the two components of the polypropylene resin and the polyethylene resin which are suitably used for the polyolefin-based splittable conjugate fiber of the present invention, the polypropylene resin becomes the high melting point resin (component A). . Specific examples of such polypropylene resins include syndiotactic polypropylene and isotactic polypropylene polymerized with a Ziegler-Natta catalyst, a metallocene catalyst, and the like. The MFR-A of the polypropylene resin which is a high melting point resin may be in a range where melt spinning is possible, and the MFR-A after fiber molding is 10 to 10 by changing spinning conditions and the like.
There is no particular problem within the range of 0 g / 10 minutes. MFR-A after fiber molding is more preferably 10 to 70 g /
10 minutes. MFR-A after fiber molding is 10 g / 10
If it is less than minutes, the hollow ratio can be maintained high, but it is easy to spin and it is difficult to spin into fine fibers. When the MFR-A after fiber molding exceeds 100 g / 10 minutes,
It is difficult to maintain a high hollow ratio, and when spinning a filament, spinnability may be deteriorated.

On the other hand, the polyethylene resin is a low melting point resin (component B) lower than the melting point of the polypropylene resin, and specifically, a high density polyethylene (HDP).
E), linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE).
Further, a mixture of two or more of these may be used. The MFR-B of the polyethylene resin as a raw material may be any range as long as it can be melt-spun, and if the MFR-B after fiber molding is within the range of 10 to 100 g / 10 minutes due to a change in spinning conditions, etc. There is no. MFR-B after fiber molding is more preferably 10 to 60 g / 10 minutes. MFR-B
If it is less than 10 g / 10 minutes, the hollow ratio can be kept high, but the spinnability becomes extremely poor, and it becomes difficult to spin fine fibers. When MFR-B exceeds 100 g / 10 minutes, it is difficult to maintain the hollow ratio, and when spinning a filament, spinnability may be deteriorated.

When the resin having the highest melting point among the at least two components of the polyolefin resin constituting the composite fiber after forming the polyolefin-based splittable composite fiber of the present invention is the component A, the MFR of the component A is MFR- A, and when the MFR of the B component when the resin having the lowest melting point is the B component is MFR-B, the ratio of the MFR (MFR-A / M
FR-B) is preferably from 0.1 to 5, more preferably from 0.5 to 3. If this value is less than 0.1 or exceeds 5, the difference between the flowability of the two components in the spinneret during melt spinning, the difference in melt tension after being discharged into a hollow shape, and the increase in viscosity during cooling. Due to factors such as
It is difficult to maintain the hollow ratio and spin with good spinnability.

The polyolefin resin according to the present invention may further contain an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizer, a nucleating agent, an epoxy stabilizer, a lubricant within a range not to impair the effects of the present invention. , Antibacterial agents, flame retardants, antistatic materials, pigments,
Additives such as a plasticizer and a hydrophilic agent may be appropriately added as necessary.

The shape of the polyolefin-based splittable conjugate fiber of the present invention is not particularly limited as long as the inside of the fiber is hollow and can be split by high-pressure liquid flow treatment or the like.
In the case of the splittable conjugate fiber composed of the two-component polyolefin resin represented by A and B, a cross-sectional shape in which the A and B components are alternately arranged can be exemplified. Of course, in the case of a splittable conjugate fiber composed of a multi-component polyolefin resin, it is preferable that each component has a cross-sectional shape in which the components are alternately arranged.

When the polyolefin-based splittable conjugate fiber obtained in the present invention is split by high-pressure liquid flow treatment or the like, the average fineness of the ultrafine fibers after splitting is 0.5 dtex or less, particularly 0.3 dtex or less. Preferably, Therefore, the number of segments of the splittable conjugate fiber having a hollow inside can be determined so that the average fineness of the ultrafine fiber is 0.5 decitex or less. Although there is an advantage that the subsequent fineness is reduced, the number of segments is preferably 4 to 32 in terms of ease of fiber production. The fineness of each segment does not need to be the same, and when the splittable conjugate fiber is not completely split, there are a plurality of different sizes between the undivided splittable conjugate fiber and the completely split ultrafine fiber. Fine fibers may be mixed.

Next, the fiber cross section of the polyolefin-based splittable conjugate fiber of the present invention will be described. The fiber cross section of the polyolefin-based splittable conjugate fiber of the present invention is at least A,
The polyolefin resin of the B2 component is a composite fiber having a hollow portion at the fiber center portion, which is arranged alternately in a radial pattern. In the fiber cross section, from the average length W of the fiber outer peripheral arc of one resin component and the hollow portion. It is necessary that the ratio (W / L) of the average thickness L to the outer periphery of the fiber satisfies 0.25 to 2.5. When W / L is less than 0.25, each segment becomes flaky. Accordingly, the splittable conjugate fiber has a structure in which thin pieces are laminated, and high energy is required to achieve splitting and fineness. That is, the contact ratio of the A and B components increases, and division becomes difficult. If it exceeds 2.5,
Because the number of divisions is small or the hollow ratio is too large, the spinning property is secured, and the fineness of a single yarn after the division and fineness does not become too small, and the present invention is easily divided into ultrafine fibers. Depart from the gist of

The area occupied by the hollow portion at the fiber center in the fiber cross section of the polyolefin-based splittable conjugate fiber of the present invention;
That is, the hollow ratio is 5% to 40%, more preferably,
10 to 30%. When the hollow ratio is less than 5%, the value of L is large, the contact area between adjacent components is large, and when the undivided fiber is divided into fine fibers by physical stress, the fibers are hardly crushed, and the A and B components are hardly broken. It is necessary to increase the energy required for peeling off at the contact interface. The hollow ratio is 40%
When the value exceeds L, the value of L becomes small, the contact area between adjacent components is small, and fine splitting by physical stress easily proceeds, but unsplit fibers are produced while maintaining spinnability and productivity. It becomes difficult to do. That is, the hollow ratio is 5% to 40%.
%, More preferably 10 to 30%, it is possible to obtain a fiber which can be easily split while maintaining spinnability and productivity. Furthermore, the hollow part is not only at the fiber center,
Alternatively, when the spinning is performed by adding a foaming agent to one of the components B, a hollow portion can be present in one of the components A or B by the action of the foaming agent. Since this hollow portion exists at the boundary between the A and B components and reduces the contact area between the adjacent components, the impact energy required for division can be reduced, and the ease of division can be significantly improved. Here, examples of the foaming agent include azodicarbonamide, barium azodicarboxylate, N, N-dinitrosopentamethylenetetramine, p-toluenesulfonyl semicarbazide, trihydrazinotriazine and the like. There is no problem even if the outer peripheral surface of the fiber is a perfect circle, an elliptical cross section, or an irregular cross sectional shape such as a triangular to octagonal square.

The shape of the hollow part in the fiber cross section of the polyolefin-based splittable conjugate fiber of the present invention partially corresponds to a curved surface having a radius of curvature (ρ) smaller than the radius (r) of a circle having the same area as the hollow part. The shape preferably includes at least one or more. In other words, the hollow shape is not a perfect circle, but by taking a shape having a partial strain, a thin portion is formed in the thickness of the hollow split-type composite fiber in which each component constituting the composite fiber is alternately arranged. The parts are easily separated due to physical stress, and are easily divided. Further, once one part of the hollow splittable conjugate fiber is peeled and split, the hollow shape becomes a horseshoe shape, and the structure becomes easy to receive the physical stress of the high-pressure liquid flow treatment, so the splitting proceeds easily. . In other words, when the cross-sectional shape of the hollow portion at the center of the fiber is not a perfect circle, but is partially a so-called uneven cross-sectional shape, the state is basically unstable against impact. For this reason, it is easily divided with smaller impact energy. The radius of curvature is not particularly limited as long as the radius of curvature (ρ) is smaller than the radius (r) of a circle having the same area as the hollow portion, since the hollow portion has a shape having distortion. When the radius (ρ) is close to the radius r of the circle, the shape of the hollow portion becomes close to a circle, and the effect of easy division is reduced, so that ρ <0.8r is more preferable, and ρ <0.7 is more preferable.
r.

In the polyolefin splittable conjugate fiber of the present invention, the conjugate ratio of the conjugate fiber composed of at least two components of the polyolefin resin is from 10/90 to 90.
/ 10% by weight, the sum of the used resin components is 10%.
0% by weight, more preferably 30 / 70-7.
0/30% by weight, most preferably a two-component polyolefin resin having a composite ratio of 50/50% by weight.
It is. By setting the compounding ratio in such a range, a cross-sectional shape in which the used polyolefin-based resin composed of at least two components is uniformly arranged is obtained. Furthermore, the fineness after division and fineness is constant, and a more uniform fiber aggregate can be obtained.

The single-filament fineness of the polyolefin-based splittable conjugate fiber of the present invention before splitting is not particularly limited.
It is preferably 0.6 to 10.0 decitex (hereinafter, sometimes referred to as dtex), and more preferably,
1.0 to 6.0 dtex. Single yarn fineness is 0.6 dt
If it is less than ex, the spinnability in the melt spinning step tends to decrease. On the other hand, if it exceeds 10.0 dtex, it becomes difficult to obtain a highly uniform fiber aggregate even if the obtained web is divided into fine fibers by a high-pressure water flow method or the like. Further, the average single fiber fineness after division is preferably less than 0.6 dtex, more preferably 0.5 dtex or less.
When it is 0.6 dtex or more, it is difficult to obtain a uniform and well-formed soft fiber molded article due to fineness, which is the largest characteristic of the split fibers.

Hereinafter, as an example of the polyolefin-based splittable conjugate fiber of the present invention, a method for producing a splittable conjugate fiber combining two components of a polypropylene resin and a high-density polyethylene resin will be described. A long fiber made of the resin is spun using a normal melt spinning machine. In spinning, the spinning temperature is preferably in the range of 200 to 330 ° C., and the take-off speed is preferably about 40 m / min to 1500 m / min. Stretching may be performed in multiple stages if necessary,
The stretching ratio is usually preferably about 3 to 9 times. Further, the obtained tow is crimped as required and then cut into a predetermined length to obtain short fibers. The above description discloses the process for producing short fibers, but it is also possible to form a long fiber tow into a web using a fiber separation guide or the like without cutting the tow. After that, it is formed into a fiber molded body according to various uses through a higher processing step as required. In addition, after spinning and drawing, the fiber molded article is wound up as a filament yarn and knitted or woven to form a knitted woven fabric, or the short fiber is formed into a spun yarn, and then knitted or woven to form a knitted woven fabric. May be formed.

That is, the fiber molded body may be in any form as long as it is in the form of a cloth.
There is a nonwoven fabric or a nonwoven fiber aggregate. Further, it can be made into a cloth form by a method such as cotton blending, blending, blending, twisting, knitting, and blending. Here, the non-woven fiber aggregate is, for example, a card-like method, an air laid method, a web-like material made uniform by a method such as a papermaking method, or a woven fabric, a knitted fabric,
It refers to one obtained by laminating various nonwoven fabrics.

In this step, after spinning the fiber, a surfactant can be adhered to the fiber surface for the purpose of preventing static electricity of the fiber and imparting smoothness for improving the processability of the fiber molded article. The type and concentration of the surfactant are appropriately adjusted according to the application. As a method of attachment, a roller method, a dipping method, a pad dry method, or the like can be used. The attachment may be performed in any of the spinning step, the stretching step, and the crimping step. Further, regardless of whether the fibers are short fibers or long fibers, a surfactant can be attached to the fiber molded article other than the spinning step, the stretching step, and the crimping step, for example, after molding the molded article.

Although the fiber length of the polyolefin-based splittable conjugate fiber of the present invention is not particularly limited, when a web is produced using a card machine, it is generally 20 to 76 m.
In general, in the paper making method and the air laid method, those having a fiber length of 2 mm to 20 mm are preferably used.
If the fiber length is less than 2 mm, the fiber will move due to physical impact, and the fiber itself will not easily receive the energy required for division. If the fiber length is significantly larger than 76 mm, the web cannot be formed uniformly by a carding machine or the like, and it is difficult to form a web having a uniform formation.

As an example of a method for producing a fibrous formed article comprising the polyolefin-based splittable conjugate fiber of the present invention, a method for producing a nonwoven fabric will be described. For example, using a short fiber produced by the above-mentioned method for producing a polyolefin-based split conjugate fiber, a required basis weight web is produced by a card method, an air laid method, or a papermaking method. Alternatively, a web may be directly produced by a melt blown method, a spun bond method, or the like. The web produced by the above method can be divided into fine fibers by a known method such as a needle punch method or a high-pressure liquid flow treatment to obtain a fiber molded body. Further, the fiber molded body can be further processed by a known processing method such as hot air or a hot roll. Also, when a web composed of very short fibers such as a paper making method is divided into fine fibers by a known method such as a needle punch method or a high-pressure liquid flow treatment, the fibers are split at the same time as the fibers move due to the physical stress. In some cases, fibers that are heat-fused at a melting point lower than the melting point of the resin constituting the polyolefin-based splittable conjugate fiber of the present invention are blended. Fabrication of the bonded nonwoven fabric can suppress formation failure.

The basis weight of the fiber molded article of the present invention is not particularly limited, but is preferably 10 to ²⁰⁰ g / m ² . When the basis weight is less than 10 g / m ² , when the fibers are divided into fine fibers by physical stress such as a high-pressure liquid flow treatment, a nonwoven fabric having poor formation may be obtained. On the other hand, if the basis weight exceeds 200 g / m ² , the basis weight is high, a high-pressure water flow is required, and it may be difficult to perform uniform and uniform division.

The fiber molded article of the present invention can be used by mixing other fibers with the splittable conjugate fiber of the present invention, if necessary, as long as it does not hinder the present invention. Examples of such other fibers include synthetic fibers such as polyamide, polyester, polyolefin, and acrylic; natural fibers such as cotton, wool, and hemp; regenerated fibers such as rayon, cupra, and acetate; and semi-synthetic fibers.

Next, the high-pressure liquid flow processing will be described.
As the high-pressure liquid flow device used for the high-pressure liquid flow treatment, for example, a hole diameter of 0.05 to 1.5 mm, particularly 0.1 to 0.5
A device in which a large number of injection holes having a diameter of 0.1 mm to 1.5 mm are arranged in a single row or in a plurality of rows is used. A high-pressure liquid stream obtained by jetting at a high water pressure from an injection hole is caused to collide with the web placed on a porous support member. Thereby, the undivided splittable conjugate fiber of the present invention is entangled and fined at the same time by the high-pressure liquid flow. The arrangement of the injection holes is arranged in a row in a direction orthogonal to the traveling direction of the web. As the high-pressure liquid flow, room temperature or hot water may be used, or another liquid may be optionally used.

The distance between the injection hole and the web is 10 to 1
It is good to be 50 mm. If this distance is less than 10 mm, the formation of the fiber molded body obtained by this treatment is disturbed,
On the other hand, if the distance exceeds 150 mm, the physical impact of the liquid stream on the web becomes weak, and confounding and fine splitting may not be performed sufficiently. The processing pressure of the high-pressure liquid flow is controlled by the manufacturing method and the required performance of the fiber molded body, but is generally 20 kg / cm ^{2 to} 200 kg.
/ Cm ² of the high-pressure liquid stream is preferably injected. Although it depends on the basis weight of the treatment, etc., within the range of the treatment pressure, when the high-pressure liquid flow is treated by sequentially increasing the pressure from a low water pressure to a high water pressure, the formation of the web is not disturbed, It becomes possible to divide the fine fibers. As a porous support member on which a web is placed when applying a high-pressure liquid flow, for example, 50 to 2
There is no particular limitation as long as the high-pressure liquid flow penetrates the web, such as a 00 mesh wire mesh or a synthetic resin mesh screen or a perforated plate.

After applying the high-pressure liquid flow treatment from one side of the web, the entangled web is subsequently inverted,
By performing the high-pressure liquid flow treatment, it is possible to obtain a fiber molded body that is dense on both sides and has good formation. After the high-pressure liquid flow treatment, moisture is removed from the treated fiber molded body. In removing the moisture, a known method can be employed. For example, after removing water to some extent using a squeezing device such as a mangrol, the water can be completely removed using a drying device such as a hot air circulation type dryer to obtain the fiber molded article of the present invention.

The polyolefin-based splittable conjugate fiber of the present invention is easier to split than conventional polyolefin-based splittable fibers, and can be split and made finer with less physical impact due to high-pressure liquid flow. For this reason, improvement of formation by high-speed high-pressure liquid flow processing and low-pressure high-pressure liquid flow, which are the rate-determining stages of spunlace, for example, in a web made of fibers having a short fiber length as in a papermaking method, the pressure of the high-pressure liquid flow Can be reduced, and problems such as the formation of the fiber molded article being disturbed and through holes being opened can be improved.

As described above, even a splittable conjugate fiber composed of polyolefin resin can be easily split, and a dense and well-formed fiber molded article can be obtained. Accordingly, the polyolefin resin can be suitably used in the field of industrial materials such as battery separators and wipers utilizing the chemical resistance of the polyolefin resin, the field of sanitary materials, and the field of medicine.

[0046]

EXAMPLES Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The terms used in the examples and comparative examples and methods for measuring physical properties are as follows.

(1) Melt flow rate (MFR) Measured according to JIS K7210. Raw material polypropylene resin: Condition 14 Raw material polyethylene resin: Condition 4 Raw material syndiotactic polystyrene resin: JIS
Measured in accordance with K7210 at a test temperature of 300 ° C and a test load of 21.18N. Polyolefin resin after fiber molding: Condition 14

(2) (W / L) Measurement Method The following values were calculated from cross-sectional photographs of arbitrarily selected 10 undivided conjugate fibers, and the W / L was calculated from the average value. W: Average value of the length of a certain component's outer circumferential arc L: Average value of the thickness of a certain component

(3) Hollow ratio (%) It was calculated from the photograph of the cross section of the undivided conjugate fiber according to the following equation. Hollow ratio (%) = (cross-sectional area of hollow part / total cross-sectional area including hollow part of fiber) × 100

(4) Number of radii of curvature (ρ) <(r) The radius (r) of a circle having the same area as the cross-sectional area of the hollow part measured in the measurement of the hollow ratio was calculated, and a cross-sectional photograph of the undivided composite fiber was obtained. To r
Count the number of smaller radii of curvature (ρ).

(5) Spinnability The spinnability at the time of melt spinning was evaluated according to the following three scales based on the incidence of the number of yarn breaks. ：: No breakage of yarn occurred and operability was good. Δ: Thread breaks occur 1 to 2 times per hour ×: Thread breaks occur 4 times or more per hour, causing operational problems.

(6) Stretch ratio Calculated by the following equation. Stretching ratio = take-up roll speed (m / min) / supply roll (m
/ Min)

(7) Fiber Tensile Strength / Elongation Measured according to JIS-L1013 method using an Autograph AGS500D manufactured by Shimadzu Corporation at a test length of 100 mm and a tensile speed of 100 mm / min.

(8) Tensile strength and elongation of non-woven fabric A non-woven fabric having a width of 5 cm was used as an autograph manufactured by Shimadzu Corporation.
The breaking strength of the nonwoven fabric in the MD direction was measured using AGS500D. Measurement was performed at a test length of 100 mm and a tensile speed of 200 mm / min, and the measurement temperature was room temperature.

(9) Measurement of splitting ratio The nonwoven fabric after splitting is covered with wax, and sliced at right angles to the fiber axis with a microtome to prepare a sample piece. This is observed with a microscope, the cross-sectional image of the fiber is image-processed, and the total cross-sectional area (A) of the fiber in which 70% or more of the segment is divided and the total cross-sectional area (B) of the undivided fiber are measured. Was calculated by the following equation. Division ratio (%) = {A / (A + B)} × 100

(10) Average single yarn fineness after division From the single yarn fineness before division and the number of segments that can be divided, the average single yarn fineness after divided fineness was calculated by the following formula. Average single yarn fineness after division (dtex / f) = fineness before division (dtex / f) / number of segments that can be divided (pieces)

(11) Formation For 10 panelists, the distribution unevenness of the fibers of the nonwoven fabric (1 m square) after the division and fine processing was visually determined and evaluated according to the following criteria. ：: Seven or more felt that there were few spots and no through holes. B: Four to six persons felt that there were few spots and no through holes. X: Three or less felt that there was little unevenness.

(12) High-pressure liquid flow treatment A web prepared by a roller card machine, an air laid machine, a paper machine, or the like is placed on an 80-mesh plain weave conveyor belt, and the conveyor belt speed is 20 m / min.
A high-pressure liquid flow was ejected by passing immediately below a nozzle having a nozzle diameter of 0.1 mm and a nozzle pitch of 1 mm. First, after a preliminary treatment (2 stages) at 2 MPa, a 4-stage treatment was performed with a high-pressure liquid flow at a water pressure of 5 MPa. Turn the web over and press 5M
By performing a four-stage treatment with a high-pressure liquid flow of Pa, a divided and finely divided nonwoven fabric was obtained. Here, the stage refers to the number of times that the ink has passed just below the nozzle.

Examples 1 to 3 Using two components, a polypropylene resin (propylene homopolymer, melting point: 163 ° C.) as the high melting point resin A and a high density polyethylene resin (melting point: 131 ° C.) as the low melting point resin B,
Using a splittable conjugate fiber base, a splittable conjugate fiber having a fiber cross-sectional shape shown in FIG. 1 having a volume ratio of resin A to resin B of 50/50 and single yarn denier of 7.5 dtex was spun. In the take-off step, the alkyl phosphate potassium salt was deposited. The obtained undrawn yarn is 90 ° C.
The film was stretched at 4.3 times, mechanically crimped, and cut into a length of 51 mm. The obtained short fibers were formed into a web by a roller card machine, subjected to the high-pressure liquid flow treatment, and then dried with a dryer at 80 ° C. to obtain a fiber molded body. The measurement results of spinning / drawing conditions, fiber properties, composite shape, non-woven fabric properties, division ratio, and the like are shown in Table 1 below.

Example 4 A polypropylene resin (propylene homopolymer, melting point: 163 ° C.) was used as the high melting point resin A, and a high density polyethylene resin (melting point: 131 ° C.) was used as the low melting point resin B.
A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 having a volume ratio of resin A to resin B of 70/30 and single yarn denier of 7.5 dtex was spun using a split type composite fiber base. In the take-off step, the alkyl phosphate potassium salt was deposited. The obtained undrawn yarn is 90 ° C.
The film was stretched at 4.3 times, mechanically crimped, and cut into a length of 51 mm. The obtained short fibers were formed into a web by a roller card machine, subjected to the high-pressure liquid flow treatment, and then dried with a dryer at 80 ° C. to obtain a fiber molded body. The measurement results of spinning / drawing conditions, fiber properties, composite shape, non-woven fabric properties, division ratio, and the like are shown in Table 1 below.

Example 5 A polypropylene resin (propylene homopolymer, melting point: 163 ° C.) was used as the high melting point resin A, and a high density polyethylene resin (melting point: 133 ° C.) was used as the low melting point resin B.
Using a splittable conjugate fiber die, a splittable conjugate fiber having a fiber cross-sectional shape shown in FIG. 2 having a volume ratio of resin A to resin B of 50/50 and single yarn denier of 4.0 dtex was spun. In the take-off step, the alkyl phosphate potassium salt was deposited. The obtained undrawn yarn is 90 ° C.
It was stretched at 4.1 times and cut into a length of 5 mm to obtain short fibers having a water content of 20% by weight. To this short fiber, 20% by weight of a sheath / core type composite fiber of polypropylene / low density polyethylene (EAC fiber, Chisso Corporation) was added, and a square sheet machine (25
cm x 25 cm) and a web was formed by a papermaking method. Use a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd.
After drying for minutes, preliminary bonding was performed to obtain a web. After performing the high-pressure liquid flow treatment, the mixture was further dried with a dryer at 80 ° C. to obtain a fiber molded body. Spinning / drawing conditions, fiber properties,
The measurement results of the composite shape, non-woven fabric physical properties, division ratio, and the like are shown in Table 1 below.

Example 6 A spinneret for splittable conjugate fiber was prepared by using a polypropylene resin (propylene homopolymer, melting point: 165 ° C.) as the high melting point resin A and a linear low density polyethylene resin as the low melting point resin B. The volume ratio of resin A to resin B was 50 /
A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 having a denier of 50 and a single yarn of 7.5 dtex was spun. In the take-off step, the alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 3.8 times, and cut into a length of 5 mm to obtain a short fiber having a water content of 20% by weight. To this short fiber, 20% by weight of a sheath / core type composite fiber of polypropylene / low density polyethylene (EAC fiber, Chisso Corporation) was added, and a square sheet machine (25 cm × 25) was added.
cm) and made into a web by a papermaking method. Dry at 105 ° C for 3 minutes using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd.
Pre-bonding was performed to obtain a web. After performing the high-pressure liquid flow treatment, the mixture was further dried with a dryer at 80 ° C. to obtain a fiber molded body. Spinning / drawing conditions, fiber properties, composite shapes,
The measurement results such as the properties of the nonwoven fabric and the division ratio are shown in Table 1 below.

Examples 7 and 8 Using a polypropylene resin (propylene homopolymer, melting point 163 ° C.) as the high melting point resin A and a high density polyethylene resin (melting point 131 ° C.) as the low melting point resin B,
FIG. 1 shows a volume ratio of resin A and resin B of 50/50 and single yarn denier of 20.0 dtex using a splittable composite fiber base.
Was spun into a splittable conjugate fiber having the fiber cross-sectional shape shown in FIG. In the take-off step, the alkyl phosphate potassium salt was deposited. The obtained undrawn yarn is 90 ° C.
The film was stretched at a ratio of 4.0 times, cut into a length of 51 mm by mechanical crimping. The obtained short fibers were formed into a web by a roller card machine, subjected to the high-pressure liquid flow treatment, and then dried with a dryer at 80 ° C. to obtain a fiber molded body. The measurement results of spinning / drawing conditions, fiber properties, composite shape, non-woven fabric properties, division ratio, and the like are shown in Table 1 below.

Example 9 Using two components, a polypropylene resin (propylene homopolymer, melting point: 163 ° C.) as the high melting point resin A and a high density polyethylene resin (melting point: 133 ° C.) as the low melting point resin B,
FIG. 2 showing a 50/50 volume ratio of resin A to resin B and a single yarn denier of 50.0 dtex using a split type composite fiber base.
Was spun into a splittable conjugate fiber having the fiber cross-sectional shape shown in FIG. In the take-off step, the alkyl phosphate potassium salt was deposited. The obtained undrawn yarn is 90 ° C.
It was stretched at 5.0 times, mechanically crimped, and cut to a length of 51 mm. The obtained short fibers were made into a web by a roller card machine, subjected to the high-pressure liquid flow treatment, and then dried with a dryer at 80 ° C. to obtain a fiber molded body. Example 1
The spinning / drawing conditions, fiber properties, composite shape, nonwoven fabric properties, division ratio, and other measurement results of No. 9 are shown in Table 1 below.

Example 10 Syndiotactic polystyrene resin (styrene homopolymer, syndiotacticity in racemic pentad: 95%, melting point 270 ° C.) was used as high melting point resin A, and polypropylene resin (propylene) was used as low melting point resin B. (Homopolymer, melting point: 163 ° C.), a fiber shown in FIG. 1 having a volume ratio of resin A to resin B of 50/50 and single yarn denier of 4.5 dtex using a split type composite fiber base. A splittable composite fiber having a cross-sectional shape was spun. In the take-off step, the alkyl phosphate potassium salt was deposited.
The obtained undrawn yarn was drawn at 120 ° C. and 1.7 times, and cut into 51 mm by mechanical crimping. The obtained short fibers were made into a web by a roller card machine, subjected to the high-pressure liquid flow treatment, and then dried with a dryer at 80 ° C. to obtain a fiber molded article of the present invention. The measurement results of the spinning / drawing conditions, fiber properties, composite shape, nonwoven fabric properties, division ratio, and the like of Example 10 are shown in Table 2 below.

COMPARATIVE EXAMPLE 1 Using two components, a polypropylene resin (propylene homopolymer, melting point: 163 ° C.) as the high melting point resin A and a high density polyethylene resin (melting point: 133 ° C.) as the low melting point resin B,
Using a splittable conjugate fiber base, a splittable conjugate fiber having a fiber cross-sectional shape (hollow ratio 0%) shown in FIG. 4 having a volume ratio of resin A to resin B of 50/50 and single yarn denier of 7.5 dtex is obtained. Spun. In the take-off step, the alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 4.5 times, mechanically crimped, and cut into a length of 51 mm. The obtained short fibers were formed into a web by a roller card machine, subjected to the high-pressure liquid flow treatment, and then dried with a dryer at 80 ° C. to obtain a fiber molded body.

Comparative Example 2 A polypropylene resin (propylene homopolymer, melting point: 163 ° C.) was used as the high melting point resin A, and a high density polyethylene resin (melting point: 131 ° C.) was used as the low melting point resin B.
The split type composite fiber having the fiber cross-sectional shape shown in FIG. 1 having the volume ratio of the resin A and the resin B of 50/50 was spun using the split type composite fiber die. Sample could not be collected.

Comparative Example 3 Using two components, a polypropylene resin (propylene homopolymer, melting point: 163 ° C.) as the high melting point resin A and a high density polyethylene resin (melting point: 131 ° C.) as the low melting point resin B,
Using a split type composite fiber base, the resin A and the resin B have a volume ratio of 50/50 and a single yarn denier of 10.0 dtex.
Was spun into a splittable conjugate fiber having the fiber cross-sectional shape shown in FIG. In the take-off step, the alkyl phosphate potassium salt was deposited. The obtained undrawn yarn is 90 ° C.
The film was stretched at 5.5 times, mechanically crimped, and cut into a length of 51 mm. The obtained short fibers were made into a web by a roller card machine, subjected to the high-pressure liquid flow treatment, and then dried with a dryer at 80 ° C. to obtain a fiber molded body. Comparative Examples 1 to
Table 2 below shows the measurement results of the spinning / drawing conditions, fiber properties, composite shape, nonwoven fabric properties, division ratio, and the like of No. 3.

[0069]

[Table 1]

[0070]

[Table 2]

As is clear from Tables 1 and 2, the divided finely divided nonwoven fabrics of Examples 1 to 10 of the present invention were obtained in Comparative Examples 1 and 2.
Compared to No.3, it is highly divided under the same conditions. That is, even if the conventional high-pressure liquid flow treatment of high water pressure is not performed, since the division and fineness easily proceed, even a relatively low-weight nonwoven fabric can be divided without disturbing the formation. The cost of liquid flow treatment can also be significantly reduced.

[0072]

As described above, the polyolefin-based splittable conjugate fiber of the present invention is very easy to split, so that it is not necessary to add an additive for easily splitting, and it is not necessary to increase the physical impact. Therefore, a dense and well-formed fiber molded body can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a fiber cross section of a splittable conjugate fiber used in the present invention.

FIG. 2 is a schematic view of a fiber cross section of a splittable conjugate fiber used in the present invention.

FIG. 3 is a schematic view of a fiber cross section of a splittable conjugate fiber used in a comparative example.

FIG. 4 is a schematic view of a fiber cross section of a splittable conjugate fiber used in a comparative example.

[Explanation of symbols]

W: Represents the average length of the outer arc of the fiber of one resin component constituting the composite fiber. L: Represents the average thickness from the hollow portion of the conjugate fiber to the outer periphery of the fiber.

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4L041 AA07 AA19 AA20 BA04 BA05 BA11 BA42 BA49 BA59 BC04 BC20 BD03 BD06 BD07 BD11 BD20 CA36 CA37 CA38 CA47 DD01 DD05 DD14 EE06 EE20 4L045 AA05 BA21 BA24 BB30 CA40 DA60 4L027 AB08 AA09 AB10 CC12 EA05

Claims (7)

[Claims] 1. A composite fiber comprising at least two components of a polyolefin resin, wherein each component is alternately arranged radially in a fiber cross-section, and has a hollow portion in the center of the fiber. The hollow ratio is 5 to 40%, and the ratio (W / L) of the average length W of the fiber outer peripheral arc and the average thickness L from the hollow portion to the fiber outer peripheral portion of one resin component constituting the fiber. ) Is 0.25 to 2.5. 2. The hollow section in the fiber cross section has a shape including at least one curved surface having a radius of curvature (ρ) smaller than the radius of a circle having the same area as the hollow section.
The polyolefin splittable conjugate fiber according to the above. 3. The melt flow rate of at least two components of the polyolefin resin constituting the fiber after fiber molding is 10 to 100 g / 10 min, and the highest melting point among the polyolefin resins. Melt flow rate (MFR) of resin component (hereinafter referred to as A component)
-A) and the ratio (MFR-B) of the melt flow rate (MFR-B) of the resin component having the lowest melting point (hereinafter referred to as component B).
The polyolefin-based splittable conjugate fiber according to any one of claims 1 and 2, wherein (A / MFR-B) is from 0.1 to 5. 4. The polyolefin splittable conjugate fiber according to claim 1, wherein the combination of at least two components of the polyolefin resin is a combination of a polypropylene resin and a polyethylene resin. 5. The polyolefin splittable conjugate fiber according to claim 1, wherein the combination of at least two components of the polyolefin resin is a combination of a stereoregular polystyrene resin and a polypropylene resin. 6. The polyolefin splittable conjugate fiber according to any one of claims 1 to 5, wherein the single yarn fineness before splitting is 0.6 to 10 dtex and the single yarn fineness after splitting is less than 0.6 dtex. Polyolefin-based splittable conjugate fiber described 7. A fiber molded article comprising at least 30% by weight or more of the polyolefin-based splittable conjugate fiber according to any one of claims 1 to 6, wherein at least 50% of the splittable conjugate fiber is split.