JPH06212515A - Tapered fiber, its production and napped product composed thereof - Google Patents

Abstract

PURPOSE:To obtain tapered fiber, capable of providing a napped product without a difference in color or gloss such as blackening, white fading or whitening of seams due to lying fuzz. CONSTITUTION:This tapered fiber is core-sheath type conjugate polyester-based fiber having at least one end formed into a tapered shape, recessed parts having 0.5-5mum diameter formed at a ratio of 0.1-20 recessed parts/100mum<2> in an exposed core part and recessed parts having 0.2-0.7mum diameter at a ratio of 20-1000 recessed parts/100mum<2> on the fiber surface other than the exposed core part. Furthermore, this napped product has the tapered fiber as fuzz.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a tense, chewy texture,
Concerning the tapered fiber which has excellent coloring properties and color depth, and which constitutes a napped product in which white blur does not occur in the seam after sewing,
Artificial suede from interior fields such as seats and carpets
The present invention relates to a polyester napped product having a wide range of uses in the fields of clothing, clothing, etc., and a tapered fiber constituting the product.

[0002]

2. Description of the Related Art Standing products such as cut pile, moquette, double russel, velour, and velvet have various appearances and textures, and interior materials for vehicles such as car seats;
It is used in a wide range of fields such as interiors for carpets and blankets; artificial suedes, clothes, etc. Fibers made of polyester, especially polyethylene terephthalate, are used for clothing.
Widely used in fields such as industrial and construction.

Particularly, in recent years, in the use of interior materials for vehicles, the excellent light resistance of polyethylene terephthalate fiber has been utilized, and the amount thereof used is rapidly increasing. However, the napped product made of this polyethylene terephthalate fiber has a harder touch than acrylic, nylon, rayon, silk, wool, etc., and the appearance such as gloss and luster is remarkably inferior. Even when dyed, the napped part of the napped product is smoother than the napped part made of natural fibers such as wool and silk, so that it is difficult to obtain a mild luster and the texture is not natural. There were drawbacks such as difficulty in obtaining color depth.

In general, in order to make the napped product look darker in color, a super bright type in which inorganic fine particles are not added to the polyester fiber may be used. However, a napped product using this fiber in the napped part has a coloring property. Although it improves, glare may be seen depending on the viewing angle, impairing luxury and
Not practical. In order to eliminate this glaring feeling, a semi-dull type thread in which a small amount of titanium oxide is added to polyester fiber is used for the napped part, but the color development deteriorates and the color turns white when dyed in a light color system. It looks and lacks luxury. In addition, the color tone of the napped portion varies depending on the viewing angle, and gloss and color density change, and it often looks partially darkened or looks whitish as if covered with dust.
Further, when the napped product is sewn, napped hair falls at the sewn portion, and the napped hair collapse portion looks whitish, so-called seam whitening occurs, which has a drawback of impairing a very high-grade feeling. One of the causes is that the refractive index of the polyester fiber is large and the surface reflectance is large due to the smooth surface shape,
There is a decrease in color developability due to a large difference in refractive index between the side surface and the cross section of the polyester fiber.

Various proposals have been made in order to improve such a drawback, that is, to improve the coloring property of the polyester fiber used for the napped portion of the napped product. First, in a core-sheath type composite fiber having a polyester fiber as a core and a cationic dyeable polyester as a sheath, the sheath is dyed in a darker color than the core so that the fiber side surface is exposed on the surface of the napped product. However, it is disclosed in JP-A-62-268855 that it is made inconspicuous. However, since the sheath is dyed with a cationic dye and darkened, the light resistance is deteriorated and it may not be used depending on the application.

Further, in the core-sheath type composite polyester fiber, by adding more titanium oxide to the core portion than in the sheath portion, the specular reflection on the side surface of the conjugate fiber is made small so that there is no great difference from the specular reflection on the cross section of the conjugate fiber. Disclosed in Japanese Patent Laid-Open No. 124858/1993, and Japanese Patent Laid-Open No. 1-306646 discloses a pile fabric having good colorability and no glare by adding inorganic fine particles having a high refractive index only to the sheath. Has been done. However, by adding inorganic fine particles having a high refractive index such as titanium oxide to the core and / or the sheath, the surface reflectance of the polyester fiber cross section approximates to the surface reflectance of the fiber side surface, and the composite fiber is raised. It has not been possible to solve the problem of white blurring and whitening of seams caused by the extreme fall of hair of the napped products.

Further, the surface (side surface) of the polyester fiber
It is known that by roughening the surface, when light hits the rough surface, the light is absorbed inside the fiber while repeating zigzag reflection in the concave portion, and the surface reflectance becomes small. There is. By applying this technology, the sheath surface of the core-sheath type composite fiber is roughened, the reflectance of the fiber surface is reduced, and the tip is tapered to diffusely reflect the light hitting the detail. It is also disclosed in JP-A-4-214412 that the reflectance is increased and the difference in surface reflectance between the fiber cross section and the fiber side surface of the polyester-based composite fiber is reduced. By this technique, the difference in the surface reflectance between the fiber cross section and the fiber side surface of the polyester-based composite fiber is reduced, and the blackening and white blurring of the napped product using the fiber as the napped part are eliminated, but the extreme whitening of the seam is achieved. It has not been enough to eliminate color spots in cases of severe hair fall.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a napped product having no color difference or gloss difference such as blackening, white blurring, whitening of seams due to hair collapse, and the like. To provide a possible tapered fiber.

[0009]

Means for Solving the Problems The inventors of the present invention have earnestly studied a napped product having polyester fibers in the napped part, as a result of a study aimed at a cloth using a high-grade wool in the napped part, and as a result, We found a napped product that has excellent coloring properties and mild luster, and has no color difference or gloss difference such as blackening, white blurring due to hair fall, whitening of seams, etc., and a soft texture.

According to the present invention, at least one of the tips is a tape.
It is a core-sheath type composite polyester fiber which is tapered in a pared shape, and the core exposed portion is formed with 0.1 to 20 recesses having a diameter of 0.5 to 5 μm / 100 μm ↑ 2. And, the diameter of the fiber surface other than the exposed core is 0.2 to 0.7 μm.
The concave fibers are tapered fibers formed at a ratio of 20 to 1000/100 μm ↑ 2. Further, the present invention is a napped product in which the core is exposed at the tip of the nap and the range of 20% or more of the nap length from the tip of the nap is tapered. A core containing 0.5 to 5% by weight of alkali-eluting particles such as colloidal silica in the sheath portion and 0.3 to 15% by weight of alkali-non-eluting particles such as titanium oxide in the core portion. It is possible to taper the tips of the naps by subjecting a napped product having naps made of sheath-type composite polyester fiber to nap raising, and to give irregularities of a specific shape to the fiber side surface and the exposed core portion of the taper. .

The core-sheath type composite polyester fiber (hereinafter abbreviated as composite fiber) in the present invention is a composite fiber having a single-core or multi-core core-sheath cross section, and is capable of melt composite spinning and has a core portion. It is preferable to use a combination of polyester components having mutual adhesiveness with the sheath portion. A single core is particularly preferable, and a single core may be concentric or eccentric.

Further, the cross section of the composite fiber and the cross section of the core part may be not only a round cross section but also a modified cross section, and the shapes of the cross section of the composite fiber and the cross section of the core part may be the same or different. The composite ratio of the core and the sheath in the composite fiber is 20/80
To 70/30 (weight ratio), especially 30/70 to 60-4
A range of 0 is preferred.

Polyethylene terephthalate (PE) is used as the polyester constituting the core and sheath of the composite fiber.
T), polybutylene terephthalate (PBT), polynaphthalene terephthalate (PEN) and the like, and a small amount of a copolymerization component such as diethylene glycol or neopentyl as long as the crystallinity of the polyester itself is not impaired. It is also possible to copolymerize glycol, cyclohexane dimethanol, cyclohexane dicarboxylic acid, isophthalic acid, sulfoisophthalic acid and its sodium salt, polyalkylene glycol and the like. Further, additives such as a gloss improver, a flame retardant, a dye improver and an ultraviolet absorber may be contained.

Further, the degree of polymerization of polyester is not particularly limited, and a range used for ordinary fibers, for example, an intrinsic viscosity of about 0.6 to 0.8 is preferably used.

In order to taper the tip of the composite fiber by alkali treatment, it is preferable that the alkali dissolution rate of the polyester used in the sheath is higher than the alkali dissolution rate of the polyester used in the core, which will be described later. Depending on the type and amount of the added inorganic fine particles, the alkali dissolution rate may be reversed in the sheath portion and the core portion, so that the combination of polyesters may be appropriately set so that the tip of the composite fiber is tapered by the alkali treatment. is necessary. However, if the difference in the rate of alkali dissolution between the polyester in the sheath and the core is too large, decomposition due to alkali treatment occurs selectively, and as a result, a good tapered shape can be obtained, but the fineness of the entire fiber decreases and Only weak napped products may be obtained. In addition, the alkali dissolution rate means that the polyester constituting the sheath portion and the core portion (when the additive is contained, the additive is added at the same composition ratio), respectively, the same fineness and the same number of filaments as the composite fiber Thread and 4
Using 0 g / liter of sodium hydroxide aqueous solution, 9
It is shown as a weight loss rate when treated at 6 ° C. for 40 minutes.

A feature of the present invention is that a specific number of recesses having different sizes are formed on the surface (sheath surface) of the composite fiber other than the exposed core portion and the surface of the exposed core portion of the tapered portion. That is, the surface of the composite fiber other than the exposed core portion (the surface of the sheath portion) has 20 to 1 concave portions having a diameter of 0.2 to 0.7 μm.
It is formed at a rate of 000 pieces / 100 μm ↑ 2, and 0.1 to 20 concave portions having a diameter of 0.5 to 5 μm are formed in the exposed core portion of the tapered portion.
They are formed at a ratio of 100 pieces / 100 μm ↑ 2.

First, the recesses formed on the surface of the composite fiber (sheath surface) other than the exposed core portion will be described. The diameter of the recess is the lowest point of the recess existing in the outer peripheral direction perpendicular to the fiber axis and the distance on the plane to the lowest point of the adjacent recess, and the distance and the number are determined by a scanning electron microscope. It can be measured. Such recesses are formed on the fiber surface (sheath surface) other than the tapered core-exposed portion, but need not be formed over the entire fiber surface other than the core-exposed portion, and at least the tip other than the core-exposed portion may be formed. The object of the present invention is achieved by being formed on the detailed surface. In order to obtain a deeper color depth and a mild luster, it is preferable to form recesses over the entire fiber surface except the exposed core.

When there are only recesses having a diameter of less than 0.2 μm as defined above, or when the number of recesses having a diameter of 0.2 to 0.7 μm is less than 20/100 μm ↑ 2, the fiber surface is There is little decrease in specular reflectance, and there is a glitter of gloss.
There is little improvement effect on netsock. On the other hand, if the diameter exceeds 0.7 μm, light is diffused, and the light absorption on the fiber surface is rather reduced. Further, the diameter is 0.2 to 0.7 μm
If the number of recesses in the range of 1000 exceeds 100/100 μm ↑ 2, the rough surface structure of the fiber surface becomes too small, and the rough surface structure collapses due to abrasion or the like, rather becoming a mirror gloss and the color tends to become dull and whitish. . In order to reduce specular reflection of light on the fiber surface (sheath surface) and promote absorption of light into the fiber, there are 50 to 500 recesses having a diameter of 0.4 to 0.6 μm / 100 μm ↑ 2. Is preferably present.

Next, the concave portion formed in the core exposed portion in the tapered portion of the composite fiber will be described. The diameter of the recess formed in the exposed core portion is the same as the definition of the diameter of the recess formed on the fiber surface (sheath surface), and the diameter and the number thereof can be measured by a scanning electron microscope. The diameter defined above is 0.5
If there are only recesses of less than μm, or if the diameter is 0.5-5 μ
When the number of recesses in the range of m is less than 0.1 / 100 μm ↑ 2, black spots are likely to occur. On the other hand, if the diameter exceeds 5 μm, the tactile sensation of a napped product using the taper fiber of the present invention as a nap is deteriorated. Further, even if the number of recesses having a diameter in the range of 0.5 to 5 μm exceeds 20/100 μm ↑ 2, the napped product also has a poor touch.

In order to reduce the light absorption of the exposed portion of the core, 0.1 to 10 concave portions having a diameter of 0.7 to 2 μm /
It is preferably present in the range of 100 μm ↑ 2.

In the present invention, the napped portion of the napped product is
By using tapered fibers in which concave portions of different shapes are formed on the exposed portion of the core of the tapered portion and the fiber surface (sheath surface) other than the exposed portion, not only blackening, white blurring, etc., but also whitening of seams It is possible to obtain a napped product in which

That is, the light incident on the fiber surface of the napped portion is canceled by the fine recesses formed on the fiber surface (sheath surface) other than the exposed core portion, and the reflected light interferes with each other, and also around the recessed portion. The reflected light decreases due to repeated reflection and absorption that occur one after another, and the specular reflectance of the fiber surface (sheath surface) decreases. On the other hand, the diameter of the concave portion formed in the exposed core portion is larger than the diameter of the concave portion formed in the fiber surface (sheath surface), and the number thereof is small. Therefore, the light incident on the exposed core portion is diffused by the concave portion. Therefore, the light absorption of the exposed core portion is reduced. Further, since the exposed core portion is tapered, the side surface and the cross section of the fiber of the napped portion cannot be distinguished.

Usually, a napped product in which polyester fibers are napped has a small specular reflectance of the polyester fiber cross section,
Since the surface of the polyester fiber has a small light absorption property, problems such as blackening, white blurring, and whitening of seams have occurred, but the present invention has solved these problems.

The tapering in the napped portion is preferably within a range of 20% or more of the napped length from the tip of the napped hair, and in order to prevent hair collapse, it is preferable that the range of 50% or less of the napped hair is tapered. . The tapered portion means a portion where the diameter of the napped hair is substantially smaller than that of the root portion of the napped hair, specifically, a portion where the diameter of the napped hair is 90% or less of the root diameter.

The napped product of the present invention preferably has a nap length of 10 mm or less, particularly 5 mm or less. 10 mm
If it exceeds, the effect of the present invention is gradually reduced. A nap density of 7 × 10 ↑ 3 to 8 × 10 ↑ 6 / cm ↑ 2 is suitable, and more desirably 10 ↑ 4 to 2 × 10 ↑ 5 /
It is cm ↑ 2. If the napped density is too high, it is difficult to uniformly taper the tips of the napped parts by the alkaline treatment described later, while if it is too low, it is difficult to form an appropriate tapered shape.

If the untapered roots of the tapered fibers that make up the naps are too thin, hair fall is likely to occur and the feel becomes weak. Therefore, the fineness of the root of the napped hair is 2
A range of -6 denier is preferred. Conventionally, when the denier is 3 denier or more, the napped part is tingling and gives discomfort, but
According to the present invention, since the tingling sensation is eliminated, fibers having a large fineness can be used as the napped portion, and the hair falling property is improved. In the napped product of the present invention, all the fibers constituting the napped part do not have to be the above-mentioned tapered fibers, and a part of the napped part, for example, 30% or more of the number of fibers constituting the napped part may be the above-mentioned tapered fiber. However, it is preferable that 50% or more is a tapered fiber.

The following method may be mentioned as one method for tapering the conjugate fiber of the present invention and forming a recess having a specific shape on the surface thereof. A core-sheath type composite polyester fiber containing 0.3 to 15% by weight of non-alkali-eluting inorganic fine particles in the core and 0.5 to 5% by weight of alkali-eluting inorganic fine particles in the sheath is By processing
It is possible to taper at least one of the tip portions into a taper shape, and to form a specific number of concave portions having a specific shape on the exposed core portion and the fiber surface other than the exposed core portion.

The non-alkali eluting inorganic fine particles contained in the core include titanium oxide, zirconium oxide, zinc oxide,
Examples thereof include lithopone and barium sulfate. Among these, titanium oxide is preferable because it is easily dispersed uniformly in polyester and has a higher refractive index than polyester. When the content of the fine particles is less than 0.3% by weight, the number of recesses formed in the exposed core of the tapered fiber of the present invention is reduced,
Even if the alkali reduction processing conditions are adjusted, the desired concave shape cannot be obtained. On the other hand, when the content of the fine particles exceeds 15% by weight, nozzle clogging and yarn breakage during spinning occur, and the spinnability is significantly impaired. The average particle size of the non-alkali-eluting inorganic fine particles is not particularly limited, but 0.1 to 20 concave parts having a diameter of 0.5 to 5 μm / 100 μm in the exposed core of the tapered fiber are used.
In order to be formed at a ratio of 2, it is preferably 1.0 μm or less, and particularly preferably 0.5 μm or less.

Examples of the alkali-eluting inorganic fine particles contained in the sheath include silica, calcium carbonate, kaolin, etc. Among them, colloidal silica having a smaller refractive index than polyester is preferable. The content of the fine particles is 0.
When it is less than 5% by weight, the number of recesses formed on the fiber surface other than the exposed core portion of the tapered fiber of the present invention is small, and the effect of the present invention is difficult to be achieved. On the other hand, when the content of the fine particles exceeds 5% by weight, although the number of concave portions increases, agglomerates of particles are likely to occur and the uniformity of yarn production is likely to be impaired.
The average particle size of the alkali-eluting inorganic fine particles is not particularly limited, but the diameter is 0.
20 to 1000 recesses of 2 to 0.7 μm / 100 μm
In order to form at a rate of ↑ 2, it is preferably 0.2 μm or less, and particularly preferably 0.1 μm or less.

The particle size of the inorganic fine particles is determined by an optical method or laser.
It is the value measured by the scattering method.

The alkali treatment conditions may be those used in ordinary alkali weight loss processing, but it is preferable to use a hydrolyzing agent solution containing a thickener from the viewpoint of uniformity of tapering. Examples of the hydrolyzing agent include alkaline compounds such as sodium hydroxide and potassium hydroxide. Depending on the case, a hydrolysis accelerator such as laurylbenzylammonium chloride or cetyltrimethylammonium chloride may be used in combination.

Examples of the thickener contained in the hydrolyzing agent include starch, natural gum, natural polymer sizing agents such as seaweed (sodium alginate); polyvinyl alcohol, sodium polyacrylate, styrene-maleic acid copolymer. Examples thereof include synthetic polymer sizing agents, etc., but are not particularly limited as long as the sizing agent is non-hydrolyzable with respect to the composite fiber and is uniformly dispersed in the hydrolyzing agent liquid. Good. The viscosity of the hydrolyzing agent solution containing the thickener is 10 at room temperature in order to suppress the hydrolyzability and the capillary phenomenon of the hydrolyzing agent solution and to obtain a desired tapered shape.
0-2000 cps. It is preferably in the range of.

Further, the alkali treatment for tapering the composite fibers constituting the napped portion of the napped product and forming the recesses is performed in the same manner as the alkali treatment of the composite fibers. Pile
By using a method such as pile weaving, moquette, double russel, velour, velvet or tufting, and electric flocking, padding with a hydrolyzing agent solution containing a thickener at the napped tip of the napped product composed of the above-mentioned composite fiber as the napped part. Coating method, gravure coating method, kiss coating method, knife coating method, printing method, rotary screen method, and method using a printing machine. Among these methods, a padding method, for example, a napped product is passed through the hydrolyzed agent liquid with the napped surface of the napped product facing down so that only the napped portion is immersed on the hydrolyzed agent liquid surface. It is preferable to use a method of squeezing with a mangle to remove the hydrolyzing agent solution, because a recess having a specific shape is formed up to the root of the napped hair. The pick-up rate when squeezing with a mangle is 30 to 70 relative to the weight of the napped product.
It is preferable to squeeze the liquid so that the hydrolyzing agent liquid is contained in an amount of 40% by weight, particularly 40 to 60% by weight. Further, the viscosity of the hydrolyzing agent liquid when it is applied by this padding method is particularly 150 to 1000 cps. Is preferable, and when sodium hydroxide is used as the hydrolyzing agent, the alkali concentration is preferably in the range of 1 to 30% by weight.

As a heat treatment method for a napped product in which the hydrolyzing agent liquid is applied to the napped portion by any of these methods, there are techniques such as dry heat treatment with hot air and infrared heater, and wet heat treatment with steam. However, in the case of dry heat treatment, the hydrolyzing agent liquid may dry up more quickly than necessary and a sufficient treatment effect may not be obtained, so the fiber composition of the napped portion,
It is preferable to appropriately select the heat treatment method, the heating temperature, the treatment time, etc. from the type, the content of the treatment agent, other treatment conditions, and the like. The heat treatment conditions include a treatment temperature of 80 to
It is preferable to perform the moist heat treatment at 180 ° C. for a treatment time of 5 to 120 minutes.

As described above, according to the present invention, the napped tip of the napped product of the napped product in which the napped portion is composed of the core-sheath type composite polyester fiber is applied with a viscous liquid containing a hydrolyzing agent, and then the napped tip is heated. A napped product having a soft texture can be obtained by forming a tapered shape and forming a specific number of concave portions in a specific shape on the exposed core portion and the fiber surface other than the exposed core portion. Further, in the dyed napped product, the light incident on the fiber surface is reduced in reflected light due to the fine recesses formed on the fiber surface (sheath surface) other than the exposed core portion, and the fiber surface (sheath surface) Has a smaller specular reflectance. Further, since the light incident on the exposed core portion is diffused by the recess formed in the exposed core portion, the light absorption of the exposed core portion is reduced, and the exposed core portion is tapered, so Distinguishing the distinction between the side and cross section of the fiber, the problem of blackening and white blurring due to the difference in gloss and color, which were the drawbacks of conventional napped products made of polyester fiber, whitening of seams especially due to extreme hair collapse Is eliminated.

[0036]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The measured values in the examples are values measured according to the following method.

(1) Intrinsic Viscosity of Polyester (dl / g) A value measured at 30 ° C. by dissolving a sample in a mixed solvent of phenol / tetrachloroethane (equal weight ratio). (2) Concavity diameter and several 3 samples were observed with a scanning electron microscope at a magnification of 5000 times or more, and one sample was observed at 2 places. The number of recesses indicates the average.

(3) Evaluation of napped product The following points were sensory evaluated. Feeling ◎: The feel is smooth on the skin and the feeling is soft. ◯: It has a smooth feel. Δ: It has a slight tingling sensation. X: It has a tingling sensation and is rough. Appearance ◎: Appropriate luster and calm appearance. ◯: It has a mild luster. Δ: The appearance is white and brown. X: There is a feeling of glare. Black spot ◎: No black spot is observed. ◯: No black line is observed. Δ: It looks dark when viewed in direct sunlight. X: Black blemishes are observed on the entire fabric. White blur ◎: No white blur is observed. ○: White blur is difficult to see even when bent. Δ: White blur is noticeable when bent and viewed from a shallow angle. X: White blur is visible on the entire fabric. Whitening of seams ◎: No whitening of seams is observed. ○: Whitening of the seams is difficult to see. Δ: Whitening of the seams is not noticeable in the navy blue type, but is noticeable in the beige type. X: Whitening of seams is noticeable in both the dark blue type and the beige type.

Example 1 A refractive index of 2.5 and an average particle size of 0.2 μm and 0.0
Polyethylene terephthalate having an intrinsic viscosity of 0.65 or polybutylene terephthalate having an intrinsic viscosity of 0.80 containing 5 μm of titanium oxide in a ratio shown in Table 1 was used as a core, and the refractive index was 1.45. Then, polyethylene terephthalate having an intrinsic viscosity of 0.68 containing colloidal silica having an average particle diameter of 0.03 μm in a ratio shown in Table 1 is used as a sheath portion, and the composite ratio of the core portion and the sheath portion is 1: 2. The composite fiber (weight ratio) was spun and wound at a speed of 1000 m / min. After winding, it was drawn 3.2 times at 75 ° C. and heat-treated at 130 ° C. under tension to obtain a drawn yarn of 200 denier / 72 filament concentric core-sheath type composite fibers.

A double Russell knitted fabric was prepared using this drawn yarn (pile density: 18000 filaments / cm ↑ 2). Polyester yarn (75 denier / 24 filament) was used as the ground yarn. This knitted fabric is cut by shearing so that the pile length becomes 3 mm, and the pin tenter is used.
At 180 ° C., a preset process was performed by dry heat. Then, in the napped portion of the obtained knitted fabric, an aqueous sodium hydroxide solution containing 3% by weight of sodium alginate as a thickener (concentration: 28% by weight, 20 ° C., 65% by a B type viscometer)
R. H. Viscosity measured under the conditions of 12,000 cps. )
Was applied with a rotary screen and then H. T. A steam treatment was performed with a steamer at a temperature of 150 ° C. for a treatment time of 5 to 15 minutes.

The treated knitted fabric is a dark blue system or a beige system.
Dyeing was carried out on an Overmeier dyeing machine using various types of disperse dyes. When the tip of the napped portion of the dyed sample was observed with an optical microscope, 25 to 30% of the napped length was tapered into a taper shape. When the exposed core portion of the tapered portion and the fiber surface other than the exposed core portion were observed with a scanning electron microscope, concave portions having the diameter and number shown in Table 1 were observed.

The pile yarns of Samples 2 to 6, which have a taper shape and a gentle taper shape, have a tense, a waist and a visually deep color forming property although the touch is soft. , Blackening, white blurring and whitening of the seams were barely noticeable. In the pile yarn of Sample 1, since the number of recesses formed in the exposed core portion was small, whitening of the seams occurred in both the navy blue type and the beige type.

[0043]

[Table 1]

Comparative Examples 1 to 8 The same procedure as in Example 1 was repeated except that the type and content of the inorganic fine particles contained in the core portion and / or the inorganic fine particles contained in the sheath portion were changed as shown in Table 2. Russell knitted fabric was created. Then, the napped portion of the knitted fabric was tapered with an aqueous sodium hydroxide solution containing a thickening agent under different treatment conditions, and dyeing of navy blue and beige. The dyed knitted fabric was evaluated. The results are shown in Tables 2 and 3.

[0045]

[Table 2]

[0046]

[Table 3]

In the double-raschel knitted fabric of Comparative Example 1, since a small amount of fine recesses were formed on the exposed core by alkali treatment, stains were hard to attach, but black spots, white blur, and whitening of the seams were particularly noticeable. -It was conspicuous in Ju system. Since the double Russell knitted fabric of Comparative Example 2 has only a small amount of large recesses formed on the surface of the sheath, the color development after dyeing has no depth, the appearance is inferior, and the whitening of seams is navy blue or -Ju system was outstanding. The double-russell knitted fabrics of Comparative Example 3 and Comparative Example 4 were inferior in appearance because white dents were not formed on the surface of the sheath, and white blurring and whitening of seams were conspicuous. In the double Russell knitted fabric of Comparative Example 5, since the diameter of the recess formed on the surface of the sheath is too large,
The light absorption was small and the appearance was very poor. Since the double Russell knitted fabrics of Comparative Example 6 and Comparative Example 7 do not have recesses of the diameter and the number specified in the present invention, black blemishes, white blurs,
The whitening of seams has not been resolved. In the double Russell knitted fabric of Comparative Example 8, the diameter and number of the recesses formed in the exposed core portion and the sheath portion are reversed from those of the knitted fabrics obtained in the examples, and the texture is inferior, and black spots, white blurring, The whitening of the seams has not been improved.

[0048]

Industrial Applicability The tapered fiber of the present invention is a core-sheath type composite fiber in which both the core component and the sheath component are made of polyester polymer, and at least one of the tip ends is tapered into a taper shape. The core exposed portion of the tapered portion and the surface of the sheath component are formed with concave portions having different diameters, and a napped product using the fibers as naps has a supple texture and excellent color development, Since it has a deep color, there is no difference in gloss or color difference such as blackening or white blurring, and whitening of the seam does not occur, it is suitable for car seats and the like.

[Brief description of drawings]

FIG. 1 is a photograph showing the surface shape of an exposed core portion of a tapered portion of a tapered fiber of the present invention.

FIG. 2 is a photograph showing the surface shape of the fiber side surface (sheath surface) in the tapered fiber of the present invention.

Claims (3)

[Claims] 1. A core-sheath type composite polyester fiber in which at least one tip is tapered in a taper shape,
The exposed core has a recess of 0.1 to 20 with a diameter of 0.5 to 5 μm.
20 / recesses having a diameter of 0.2 to 0.7 μm are formed on the fiber surface other than the exposed core portion.
Tapered fibers formed at a ratio of up to 1000 pieces / 100 μm ↑ 2. 2. A core-sheath type composite polyester having a core portion containing 0.3 to 15% by weight of non-alkali eluable inorganic fine particles and a sheath portion containing 0.5 to 5% by weight of alkali eluting inorganic fine particles. A method for producing a tapered fiber, which comprises subjecting a base fiber to an alkali treatment to form a taper end. 3. A napped product having napped fibers of the tapered fiber according to claim 1, wherein the core is exposed at the tip of the napped part.