WO2001061083A1

WO2001061083A1 - Modified cross-section fiber and production method therefor

Info

Publication number: WO2001061083A1
Application number: PCT/JP2001/001195
Authority: WO
Inventors: Akira Ebihara; Teruyoshi Kawada; Sunao Takahira; Mamoru Harada; Masao Morioka; Toshiro Ono
Original assignee: Kanebo, Limited; Kanebo Gohsen, Limited
Priority date: 2000-02-21
Filing date: 2001-02-20
Publication date: 2001-08-23
Also published as: AU2001232349A1

Abstract

A modified cross-section fiber characterized in that a fiber cross-section shape is formed by combining a center element with 5 to 30 flower petal-like protrusions continuing and radially extending from the center element toward the outer periphery of the fiber, a length from the base to the tip end of each petal-like protrusion is 3 to 45% of the maximum outer diameter of the fiber, and each petal-like protrusion has at least two edges having angles of 45 to 115 degrees. The modified cross-section fiber is excellent in very-fine-fiber effect and physical effect due to a modified cross-section, and is applicable to, e.g., a rubbing cloth that is finely and uniformly oriented, and to a cleaning cloth, wiping cloth or texture cloth that can remove firmly deposited fine dust; and a production method for the fiber is provided.

Description

Description Unusual cross-section fiber and method for producing the same

TECHNICAL FIELD The present invention relates to a modified cross-section fiber having excellent physical effects such as rubbing for liquid crystal and cleaning for a hard disk, and a method for producing the same. More specifically, the present invention relates to a modified cross-section fiber having a petal-like protrusion in cross-section of a fiber and having at least two edge angles, and a method for producing the same. Background art

Conventionally, fibers of various cross-sections have been used in various shapes for clothing and the like, and have been used for polishing because they have a better physical action than round cross-sections, and in recent years also for rubbing cloths.

That is, rubbing is an alignment treatment method in which an alignment film covering a transparent electrode on a glass substrate is aligned in a certain direction using a member such as a polishing cloth in a liquid crystal display element manufacturing process.

Conventionally, as such a rubbing cloth, a cloth obtained by raising the woven fabric surface of synthetic fibers of nylon or polyester, chemical fibers such as rayon, or natural fibers such as cotton has been generally used. The conventional rubbing cloth is made by raising a large number of fibers, and the alignment film is rubbed at the fiber tip or at the fiber side close to the tip. The fiber diameter was too large to obtain a fine orientation.

In order to solve this problem, JP-A-62-269932, JP-A-02-198420 and the like attempt to obtain fine orientation using ultrafine fibers.

On the other hand, JP-A-56-97319, JP-A-6-469692, and JP-A-2772837 disclose attempts to obtain fine orientation using not-fine fibers but irregular-shaped fibers. As for irregular cross-section fibers, Japanese Patent Publication No. 39-29636 and Japanese Patent Publication No. 60-24845 disclose a fiber having a sharp edge by division, and Japanese Patent Application Laid-Open No. 279897 discloses a tooth profile. A cross-section fiber is disclosed.

Conventionally, hard disk cleaning, that is, cleaning treatment for removing fine dust and impurities adhering to the disk surface using a cloth and a liquid in the hard disk manufacturing process, has conventionally been performed using natural fibers such as cotton, nylon or polyester. Fabrics, liquids, etc., of non-synthetic cross-section ultrafine synthetic fibers, such as fabrics, nonwoven fabrics, flocky, etc., are generally used.In particular, in the case of synthetic fibers, ultrafine fibers are often used in response to fine dust .

However, in the case of rubbing, when ultrafine fibers are used to obtain a fine orientation as disclosed in JP-A-62-269932, JP-A-02-198420, etc., a pile or the like is used because the fibers are too thin. The part to be raised is collapsed, and the rubbing effect itself is not sufficiently obtained.

Further, when a fiber having only a groove in the length direction as disclosed in JP-A-56-97319 and JP-A-6-46932 is used, a portion in contact with the alignment film is rounded. The rubbing effect is insufficient. In addition, the fiber described in Japanese Patent No. 2772837 in which the outer end of the projection has an acute angle is difficult to actually produce industrially due to a problem in manufacturing technology.

On the other hand, the fiber having a sharp edge as disclosed in Japanese Patent Publication No. 39-29636 and Japanese Patent Publication No. 60-24845 is not a multilobal fiber but a triangular shape of the divided fiber. Therefore, there is little contact between the edge of the portion that comes into contact with the material to be rubbed and the alignment film, and a precise rubbing effect cannot be expected. Japanese Patent Application Laid-Open No. 279897 discloses a multi-lobed filament from which the easily soluble component has been removed. No rubbing effect requiring physical action cannot be expected because there is no clear disclosure.

In addition, when a cloth made of ultrafine synthetic fibers is used for the cleaning cloth in response to fine dust, the fibers themselves are extremely fine, and the fibers themselves are rubbed by friction during cleaning. Due to the breakage or the displacement of the ultrafine fibers in the fabric structure due to the frictional stress, it is not possible to sufficiently remove the fine dust adhered firmly. Furthermore, if the dust has a strong adhesion to the disk, it cannot be sufficiently removed with a liquid.

In addition, when cotton is used for the hard disk cleaning cloth, there is a problem that dust is generated from the cloth itself.

The present invention solves the above-mentioned problems by providing excellent effects of ultrafine fibers and physical effects due to irregular cross-sections.For example, a rubbing cloth that performs fine, dense, and homogeneous orientation, and fine dust that is firmly attached It is an object of the present invention to provide a modified cross-section fiber that can be used for a cleaning cloth that can also remove blemishes, a wiping cloth, and a textured cloth, and a method for producing the same. Disclosure of the invention

In order to achieve the above object, the present invention requires the following configuration.

That is, the present invention provides a fiber cross-sectional shape comprising a central portion and a shape obtained by combining 5 to 30 petal-like projections which are continuous with the central portion and extend radially from the center toward the outer periphery of the fiber. The length from the base to the tip of the petal is 3 to 45% of the maximum outer diameter of the fiber, and each petal has at least two edges of 45 to 115 degree angle. It is a cross section fiber.

A rubbing cloth which is a cloth used for rubbing for liquid crystal alignment, wherein the rubbing cloth uses the irregular cross-section fiber in a portion in contact with a rubbing material.

Further, it is a cloth used for cleaning a hard disk, and is a cleaning cloth using the irregular cross-section fiber in a portion in contact with a disk material.

Further, the composite fiber is composed of at least two polymers, and one of the two polymers is a polymer having higher solubility than the other polymer, and the cross-sectional shape of the composite fiber is The polymer with low solubility is located almost at the center, and the polymer with high solubility forms 5 to 30 independent segments exposed on the outer periphery of the conjugate fiber. The bonding ratio between a polymer with a low solubility and a polymer with a high solubility is It is a composite fiber characterized by a ratio of 1: 2 to 9: 1.

The modified cross-section fiber according to the present invention can be produced by subjecting the conjugate fiber to conjugate spinning, and then dissolving and removing a polymer having high solubility. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view showing an example of a cross-sectional shape of a fiber constituting a rubbing cloth of the present invention.

FIG. 2 is a view showing an example of a petal-like projection in a cross-sectional shape of a fiber constituting a rubbing cloth of the present invention.

FIG. 3 is a view showing an example of a petal-like projection in a cross-sectional shape of a fiber constituting the rubbing cloth of the present invention.

FIG. 4 is an example of a cross-sectional view of a conjugate fiber used in the production of the present invention.

FIG. 5 is an example of a cross-sectional view of a conjugate fiber outside the present invention.

FIG. 6 is a schematic view of a raised cloth for a liquid crystal rubbing cloth using the modified cross-section fiber of the present invention.

FIG. 7 is an example of a schematic diagram of a die for spinning the conjugate fiber used in the present invention. FIG. 8 is an example of a schematic diagram of a die for spinning the conjugate fiber used in the present invention, and is a cross section taken along line XX ′ of FIG.

FIG. 9 is an example of an electron micrograph of a cross section of a fiber constituting the rubbing cloth of the present invention, showing a cross-sectional shape of the fiber.

Next, reference numerals will be described.

A is the modified cross-section fiber of the present invention.

B is petals.

L1 is the maximum outer diameter, and L2 is the length from the base to the tip of the petal. E is the edge angle of the petals of the present invention.

F is the edge angle of the petal of the present invention.

〇 is a pile. P is a base cloth. · In FIGS. 7 and 8, reference numeral 1 denotes an inner core orifice, which is a polymer (b) flow path. 2 is a polymer (a) flow path, 3 is a polymer (b) flow path, 4 is a conducting hole, and 5 is an orifice. A is a polymer having high solubility, and b is a polymer having low solubility. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.

The fiber used in the present invention is a synthetic fiber, and polyester, polyamide, polyolefin and the like are useful. Examples of the polyester include polyethylene terephthalate, polybutyrene terephthalate, polyethylene naphthalate, polyethylene oxybenzoate, poly 1,4-dimethylcyclohexane terephthalate, polypivalolactone, and copolyesters containing these as main components. is there. Examples of the polyamide include nylon 6, nylon 66, nylon 1.1, nylon 12, nylon 61, and copolyamides containing these as main components. As the polyolefin, for example, polyethylene, polypropylene and the like are useful. When used for rubbing, polyester, nylon 11 and nylon 12 are preferred. When used for a cleaning cloth, polyester and nylon 6 are preferred.

Next, the cross-sectional shape of the modified cross-section fiber in the present invention will be described with reference to FIGS. 1, 2, and 3. FIG. FIG. 1 shows the cross-sectional shape of the modified cross-section fiber of the present invention, and FIGS. 2 and 3 show an example of the tip of a petal-like projection.

The cross-sectional shape of the irregular cross-section fiber in the present invention is continuous with the center portion (A) of the fiber and the center portion (A) of the fiber, that is, a plurality of petal-like projections (B) connected to the center portion (A). Each petal-like projection (B) has a shape extending radially from the center (A) toward the tip of the fiber.

Further, each protrusion (B) has at least two edges. That is, each protrusion

In (B), the starting point of the protrusion, which is the overlapping part of the protrusion (B) and the center of the fiber (A) If the two parts are (e) and (f), respectively, and the end points of the outer periphery extending toward the outer periphery of the fiber are (e,) and (f '), respectively, then (e) (e,) and (f) The line connecting (f ') and (e') (f ') on the outer periphery of the protrusion is a straight line or a curve close to a straight line, and (e) (e') (f ') and (ί) (f ') (e') is at least two edges.

The angle (E :), (F). Of each edge toward the inside of the protrusion must be between 45 and 115 degrees. That is, when rubbing, by setting the angles (E) and (F), which are the contact surfaces with the rubbed member, to 45 to 115 degrees, a sharp edge acts and uniform orientation can be obtained.

For angles (E) and (F), line (e) (e,), line (e ') (ί,), line (f)

If any of (f ') is a curve, use the tangent of the curve to calculate the edge angle. That is, if the line (e) (e ') is a curve at the angle (E), the curve

(e) The angle between the tangent s at (e ') to (e') and the line connecting (e ') and (f') to the inside of the projection of the edge is defined as angle (E). . If the line (e ') (f') is a curve, the tangent t at (e ') to the curve (e') (f ') and the line connecting the line (e) (e') Angle (E) is the angle of the edge projection toward the inside. Line (e) (e ') and line

If the two connecting (e ') and (f') are curves, the tangent s at (e ') to the curve (e) (e') and the curve (e ') (f') Let the angle (E) be the inward angle of the protrusion of the edge with the tangent t at (e '). Similarly, if the angle (F) is a curve, its tangent is used for calculating the angle.

In addition, the depression between one petal and its adjacent projection, that is, between each petal

(G) may be V-shaped or U-shaped. The central portion of the cross-sectional shape may have a hollow portion.

In addition, the length (L2) from the base to the tip of each petal-like projection on the fiber section of the rubbing material to be raised or on the fiber cross section of the fabric of the cleaning cloth is 3 to 45 times the maximum fiber outer diameter (L1). %, And by specifying the ratio of (L 2) and (L 1) in this way, it is possible to increase the rubbing effect without breaking down the hair, and to suppress the deviation of the fibers in the woven fabric and provide a strong It can demonstrate cleaning power. Here, the length (L 2) from the center to the tip of each petal on the fiber cross section means the length between (e) and (e ') or the length between (f) and (f') I do. Here, the starting point of the projection, which is the overlapping portion of the projection (B) and the center (A) of the fiber, is used as the base, and the curve connecting the starting points is used as the center.

On the other hand, the number of the petals of the present invention needs to be 5 to 30, preferably 5 to 10. If the number of petals is less than 5, the number of edges is small, and precise orientation cannot be obtained even when rubbing is performed. In addition, the capture of fine dust is reduced, and a sufficient cleaning effect cannot be obtained. If the number is more than 30, the interval between the projections becomes narrow, and a precise orientation cannot be obtained even when rubbing is performed. Also, the petals become too small, and the petals are crushed by friction during cleaning.

In addition, the maximum outer diameter (L 1) of the modified cross-section fiber fiber of the present invention is preferably 7 to 30 m when used for a rubbing cloth. When the maximum outer diameter is in this range, an optimum pile density for rubbing is obtained, hair is hardly broken down, and a dense orientation is obtained at the time of rubbing. That is, the length is preferably 7 m or more from the viewpoint that hair is hard to fall, and is preferably 30 m or less from the viewpoint that an optimum pile density is obtained and a dense orientation is obtained.

When the fiber of the present invention is used for a rubbing cloth, it is preferably used, for example, for a pile portion of a pile-like structure as shown in FIG. In this case, the pile's filament density is preferably 20,000 to 50,000 filaments / cm ² , and the pile length is preferably l to 3 mm. The angle between the base fabric and the pile is not particularly limited, but is preferably 60 to 120 degrees. The type of the base fabric to be used is not a problem as long as it is an ordinary woven or knitted fabric, but a woven fabric is preferable in view of dimensional stability. Use a conductive fiber in which a conductive component is kneaded into a pile or a base cloth to make a base cloth with excellent antistatic properties, or combine the fiber used for the base cloth with polyester and a low-melting polyester to heat-treat the low-melting polyester. It is also good to dissolve and glue the base of the pile to prevent the hair from falling down.

When the fiber of the present invention is used for a cleaning cloth, it is preferably used for the weft portion of a satin woven fabric. In this case, the weft and filament density is between 100 and 100 Lament Z cm is preferred.

Further, when used for a cleaning cloth, the maximum fiber outer diameter (L 1) is preferably 7 to 30 // m. When the maximum outer diameter is in this range, an optimum weft density for a cleaning cloth can be obtained, a sufficient grinding effect can be obtained, and fine dust can be efficiently cleaned. That is, 7 m or more is preferable from the viewpoint of obtaining a strong grinding effect, and 30 m or less is preferable from the viewpoint of increasing the weft density and increasing the efficiency of cleaning fine dust.

Next, the method for producing the modified cross-section fiber of the present invention will be described below.

In general, there are methods for producing irregular cross-section fibers, such as direct spinning, and dissolving or splitting of conjugate fibers, but any method can be used as long as the above-mentioned irregular cross-section fibers can be obtained. It is. However, as a method for obtaining the above-mentioned irregular cross-section fiber industrially stably, there is a method of dissolving the conjugate fiber as follows.

In the method for producing an irregular cross-section fiber according to the present invention, a composite fiber comprising a plurality of polymers having different solubilities in a solvent is used, and at least two edges are obtained by dissolving a polymer having a solubility in a dog. A fiber having an irregular cross section is produced.

The conjugate fibers used in the present invention must have different solubility in a solvent. Here, a description will be given using a composite fiber composed of two types of fiber-forming polymers, wherein one of the two types of polymers is composed of a polymer that is easily dissolved in water or an aqueous solution of Alcali.

Examples of the polymer having low solubility include polyester, polyamide, and polyolefin. When used for rubbing, polyester, nylon 11 and nylon 12 are preferred. When used for a cleaning cloth, polyester and nylon 6 are preferred.

Further, as a polymer having high solubility, a copolymer polyester having a high hydrolysis rate, for example, a polyethylene terephthalate copolymerized with dicarbonic acid having a polyalkyleneglycol / metal sulfonate group is useful. . Also other polymers Water-soluble (including hot water-soluble) polymers are also preferred because of their versatility. Polyoxyethylene, polyvinyl alcohol, water-soluble polyamide and the like are useful as the water-soluble polymer. Polyoxyethylene having a relatively large molecular weight, for example, 100,000 or more, particularly preferably 500,000 or more is often preferable, and polypinyl alcohol having a melting point of about 150 to 180 ° C. is preferable. . Examples of the water-soluble polyamide include a polyamide comprising a carboxylic acid and a diamine in which one or both ends of a piperazine ring are alkylaminated, and a polyamide obtained by copolymerizing a lactam and the like. For example, a polyamide composed of N, N'bisaminopropylpyrazine and adipic acid is preferable because it is soluble in hot water.

In the polymer used for the conjugate fiber of the present invention, it is necessary that the bonding ratio between the polymer having low solubility and the polymer having high solubility is 1: 2 to 9: 1. If the ratio of the polymer having higher solubility than 1: 2 is large, the center of the polymer becomes small and the hair falls down, and the rubbing effect is not sufficient. If the ratio of the polymer is large, a rubbing effect cannot be sufficiently obtained because a necessary and sufficient depth and a dense alignment groove are not formed to align the liquid crystal in rubbing.

In the polymer used in the conjugate fiber of the present invention, the viscosity ratio during melting of the polymer having high solubility and the polymer having low solubility at the time of melt spinning is preferably 0.5 to 2.0. Preferably it is 0.7 to 1.8. Such a viscosity ratio can be measured by the ratio of the reciprocal of the MI value of a polymer having high solubility and the reciprocal of the MI value of a polymer having low solubility measured at a temperature equal to the melt spinning temperature. The measurement of such MI value is defined by the following method.

Put the orifice (hole diameter 0.5, hole length 1.0 thigh) and piston in the cylinder of the melt indexer, set the temperature to a predetermined value, and after the temperature rises to the set value, Stabilize for at least 5 minutes.

Pull out the piston from the cylinder, and put about 3 g to 5 g of sample into the sample port of the cylinder using the mouth. The sample is pushed firmly with a push rod and the piston is inserted. This time is defined as the preheating start point, and time measurement is started from the preheating start point.

Next, put a weight of 2160 g on the piston.

Count from the starting point of preheating, and accurately measure the weight of the sample extruded from the orifice to 1 nig on the balance for 3 minutes between 6 and 9 minutes later.

This measurement is repeated three times, and when the average value of the three weight measurements is defined as Mg,

The Ml value is defined by the following equation.

M I value = (10/3) X M

By specifying the viscosity ratio in this manner, the polymer having low solubility after removing the soluble dog polymer can be provided with an edge of 45 to 115 degree angle, If it is less than 5, the edge angle will exceed 115 degrees, and if it exceeds 2.0, the edge angle may be less than 45 degrees. For this purpose, for example, there is a method of reducing the water content of a polymer having high solubility during melt spinning to 100 ppm or less.

The conjugate fiber of the present invention uses a combination of the above-mentioned polymers and has a specific shape described below.

Hereinafter, the shape of the composite fiber of the present invention will be described with reference to the drawings.

FIG. 4 shows an example of a cross section of the composite fiber of the present invention.

In the drawing, H indicates a polymer having low solubility, and I indicates a polymer having high solubility. Here, the polymer having low solubility is a fiber-forming polymer, and the polymer having high solubility is a polymer which is a fiber-forming polymer and is easily dissolved in water or an aqueous alkaline solution. The polymer with low resolvability is continuous to the center of the single yarn, that is, a core segment connected to the center and having a petal-like projection at the tip. The polymer with high solubility is composed of segments that are exposed from the outer periphery of the fiber to the inside of the fiber, and the number of segments is 5 to 30 and each segment exists independently of each other. And discontinuous. The core segment, a polymer having low solubility, separates each segment of the polymer having high solubility.

The maximum outer diameter of the conjugate fiber of the present invention is 7 to 30 when used for a rubbing cloth. m is preferred. When used for a cleaning cloth for a hard disk or the like, the diameter is preferably 30 to 30 m.

Weaving or knitting is performed using the conjugate fiber of the present invention, and substantially all of the soluble dog polymer is dissolved and removed to obtain the above-described rubbing cloth and cleaning cloth of the present invention. Further, the conjugate fiber of the present invention can be used as a stable, processed into a non-woven fabric and dissolved and removed easily soluble components.

Action)

The effect of the modified cross-section fiber of the present invention will be described.

In order to perform fine, dense, and uniform orientation in the rubbing treatment, it is necessary that the portion in contact with the alignment film of the rubbed member is fine, dense, and the rubbing treatment of the rubbed member is constant.

In the present invention, since the atypical cross-section fiber of the present invention has a plurality of petal-like projections and each petal-like projection has two or more corner edges, the portion of the fiber that comes into contact with the alignment film is the petal projection. Finer, denser and more uniform alignment can be obtained because the film is thinner by the number of layers and the edge surface has a high alignment regulating force. Further, by specifying the ratio of the length from the base to the tip of each petal-shaped protrusion of the fiber and the maximum outer diameter of the fiber, the stability of the single fiber itself is obtained, and the brushed fabric is uniform without falling down. And a fine and dense orientation action can be produced. In addition, when the fiber of the present invention is used for a cleaning cloth, since the atypical cross-sectional fiber of the present invention has a plurality of petals and each petal has two or more corner edges, Petals with a thickness equivalent to ultrafine fibers and with two or more sharp edges are not only fixed to the core of the filament, but also adjacent to each other. By preventing the filaments in the fabric structure and thus the petal-like protrusions from shifting, the grinding effect of the sharp wedges of the petal-like protrusions is effectively exerted, and sufficient cleaning is carried out even for fine dust adhered firmly. It is effective.

Hereinafter, the present invention will be described specifically with reference to examples. (Example 1)

Polyethylene terephthalate (hereafter referred to as polymer P1) with an intrinsic viscosity of 0.64 measured with a mixed solution of phenol and tetrachlorene 6: 4 (weight ratio) at 20 ° C, an intrinsic viscosity of 0.688, and softening A polyethylene glycol copolymer (hereinafter referred to as polymer P2) having a temperature of 244.5 ° C and an alkali-soluble property was prepared. The polymer P2 was dried to a moisture content of 54 ppm. The MI values of the dried polymers PI and P2 at 290 ° C were 2.55 and 1.44, respectively. Next, polymer P1 was melted at 295 ° C and polymer P2 at 280 ° C using separate screw extruders, and metered and extruded with a gear pump so that P1ZP2 = 2 21 (volume ratio). Guided to the die pack shown in Fig. 7 and Fig. 8 at 290mm, extruded from the orifice, composite-spun both components, wound up at 1 152mZm i η, then rolled 3.27 times with a hot roller at 85 ° C. It was stretched, contacted with a hot plate at 150 ° C, and heat-treated to obtain a multifilament of 109.8 dtex / 50 f composite fiber. Let A be the sample name of this multifilament. Fig. 4 shows a cross-sectional view.

(Example 2)

Except for changing the fineness, a multifilament having a fineness of 222.3 dtex was obtained in the same manner as in Example 1. Let B be the sample name.

(Example 3)

1 11 1. Composite fiber of ldtex / 50 f in the same manner as in Example 1 except that the cap pack was changed to that of Fig. 8 for 16 divisions and the capacity ratio was changed to P1ZP2 = 3/1. Was obtained. Let C be the sample name.

(Comparative Example 1)

11 1 1.The composite fiber of ldte xZ50 f was prepared in the same manner as in Example 1 except that the cap pack was changed to one for 32 splits and the capacity ratio was changed to P1 / P2 = 3X1. Was obtained. Let D be the sample name.

(Comparative Example 2)

Except that the capacity ratio was changed to PlZPZ-l0Z1, the same method as in Example 1 was used. A multifilament of a composite fiber of 1.1 cite xZ50 f was obtained. Let E be the sample name.

(Comparative Example 3)

A multifilament multifilament of 111.1 dtex x50f was obtained in the same manner as in Example 1, except that the moisture content of the polymer P2 after drying was 194 ppm. Let F be the sample name.

(Example 4)-Nylon 6 (hereinafter referred to as polymer P3) having a relative viscosity of 2.51 and polymer P2 were prepared. The polymer P2 was dried to a moisture content of 67 ppm. Next, polymer P 3 is melted at 270 ° C and polymer P 2 at 273t: using separate screw extruders, and then pumped. 3? 2 = 371 (volume ratio), extruded into a die pack as shown in Fig. 7 and Fig. 8 at 270 ° C, extruded from the orifice and combined spinning both components, at 1152m / min The film was wound up, stretched 2.75 times with a hot mouth at 77 ° C., contacted with a hot plate at 160 ° C., and heat-treated to obtain a multifilament of 111. ldtex / 50 f conjugate fiber. Let G be the sample name.

(Comparative Example 4)

Polyethylene terephthalate having an intrinsic viscosity of 0.64 as measured with a mixed solution of phenol and tetrachloroethane 6: 4 (weight ratio) at 20 ° C is melted with a 295 ° C screw extruder and metered and extruded with a gear pump. Guide to a 290 ° C yarn pack for irregular cross-section yarn, extrude from the orifice, wind at 1152m / min, then stretch 3.27 times with an 85 ° C hot-hole, and heat at 150 ° C And heat-treated to obtain 83.3 dtex / 36 mm multifilament. Let the sample name be Η. Fig. 5 shows the cross-sectional view.

Next, 83.3 dtex / 24 f core-sheath composite fiber composed of polyester for the core and low-melting polyester for the sheath is used for the warp of the ground yarn constituting the base fabric. Using the composite fibers obtained in Examples 1 to 3 and Comparative Examples 1 to 4, the weft was composed of a core-sheath composite fiber of 55.5 dtex / 12 f and a conductive composite fiber of 22.2 dtex / 6 f. Velvet fabric was produced using twisted yarn. The resulting woven fabric is subjected to alkali reduction at 95 ° C for 20 minutes using a 1% aqueous sodium hydroxide solution to dissolve and remove the highly soluble polymer, and heat-treated to form a rubbing cloth. A rubbing treatment was applied to the polyimide film for liquid crystal. The cross section of the fiber of the obtained pile was photographed by an electron microscope, and the cross section was measured. An electron micrograph of Example 1 is shown in FIG.

Table 1 shows the results.

table 1

In Example 2, fine, dense, and uniform alignment grooves could be formed in the applied polyimide film as the rubbing member. In Example 3 in which the number of petals was increased to 16, a good rubbing effect was obtained, but in Comparative Example 1 in which the number of petals was increased to 32, the nurturing of the raised portion was not observed, but the space between the petals was narrow. As a result, sufficient alignment grooves could not be formed. In Comparative Example 2 in which the length of the petals was 2.6%, the length of the petals was too short to form a sufficient alignment groove. In Comparative Example 3, in which the moisture content of the P2 polymer was set to 194 ppm, the difference in viscosity balance between the two polymers during melting was too large, resulting in increased exposure of the P2 polymer to the fiber surface in the cross-sectional shape. As a result, the edge angle was as large as 130 degrees, and the rubbing effect was reduced. Even if it has petal-like protrusions as in Comparative Example 4, a fiber having a small number of petal-like protrusions and no edge formed at all did not form a necessary and sufficient dense alignment groove.

(Example 5) Using the conjugate fiber obtained in Example 1 for the weft, polyester for the warp, weaving five satin woven fabrics, using a 1% aqueous sodium hydroxide solution at 95, and reducing the alkali for 20 minutes After dissolving and removing the polymer with high solubility by carrying out, a woven fabric with a warp density of 120 threads Z 2.5 cm (120 threads Z inch) and a weft density of 150 threads / 2.5 cm (150 threads / inch) I got The obtained woven fabric was slit at a width of 40 mm in the warp direction, and then wound into a roll to obtain a tape-shaped cleaning cloth.

When the obtained cleaning cloth was used in a hard disk cleaning process, the fine edges of the obtained weft fibers acted, and an excellent cleaning effect was obtained. The maximum outer diameter of the obtained fiber was 14.2 rn, the number of petals was 8, and the ratio of the length from the base to the tip of the petal to the maximum outer diameter of the fiber (L2ZL1) was 2 '. 4.4%, edge angle was 85 degrees.

(Example 6)

When the conjugate fiber obtained in Example 4 was used as a cleaning cloth in the same manner as in Example 5, fine edges of the obtained weft fibers acted, and an excellent cleaning effect was obtained. The maximum outer diameter of the obtained fiber was 15.4 / m, the number of petals was 8, and the ratio of the length from the base to the tip of the petal to the maximum outer diameter of the fiber (L2 / L1) Was 22.2% and the edge angle was 88 degrees.

(Comparative Example 5)

When the conjugate fiber obtained in Comparative Example 2 was used as a cleaning cloth in the same manner as in Example 5, the groove depth between the petal-like projections was not sufficient, and the petal-like projections between adjacent filaments were interlocked. No increase in grinding power was observed, and fine dust adhered firmly could not be removed, and the cleaning effect was not sufficient. The maximum outer diameter of the obtained fiber is 14.3 m, the number of petals is 8, and the ratio of the length from the base to the tip of the petal to the maximum outer diameter of the fiber (L2ZL1) is 2.6. %, The edge angle was 91 degrees.

(Comparative Example 6)

The fiber obtained in Comparative Example 4 was treated in the same manner as in Example 5 except for the weight loss step. When used as a leaning cloth, fine dust on the hard disk could not be removed because the number of petals was small and there were no sharp edges. Industrial applicability

As described above, the irregular shaped fiber of the present invention can impart fine and uniform orientation to the material to be wrapped by performing rubbing using a liquid crystal rubbing cloth. It can also be used for hard disk cleaning to remove fine dust. In addition, it can be applied to polishing, wiping cloth, texture cloth, medical use, clothing use, etc., where the edge is effective.

Further, according to the conjugate fiber of the present invention, such a modified cross-section fiber can be industrially manufactured stably.

Claims

1. The cross-sectional shape of the fiber is composed of a combination of a central portion and 5 to 30 petal-like projections that are continuous with the central portion and extend radially from the center toward the outer periphery of the fiber. Characterized in that the length from the tip to the tip is 3 to 45% of the maximum outer diameter of the fiber, and each petal has at least two edges of 45 to 115 degrees.

fiber. '

2. A rubbing cloth which is a cloth used for rubbing for liquid crystal alignment, wherein the rubbing cloth uses the modified cross-section fiber according to claim 1 in a portion which comes into contact with a rubbing material.

Enclosure

3. A cleaning cloth for cleaning a hard disk, wherein the cleaning cloth uses the irregular cross-section fiber according to claim 1 in a portion in contact with the disk material.

4. A composite fiber composed of at least two polymers, one of the two polymers being a polymer having a higher solubility than the other polymer, and the cross section of the composite fiber The polymer having a low solubility is located almost at the center, and the polymer having a high solubility has a shape of 5 to 30 independent segments exposed to the outer periphery of the composite fiber. A composite fiber, wherein the bonding ratio between the polymer having low solubility and the polymer having high solubility is 1: 2 to 9: 1.

5. A method for producing a fiber having a modified cross section, comprising conjugate spinning the conjugate fiber according to claim 4, and then dissolving and removing a polymer having high solubility.