JPH08246338A - Core-sheath fibrillated fiber or fabric - Google Patents

Abstract

(57) [Abstract] [Purpose] It is a natural fiber-like material that can be fibrillated by a simple method and is formed by minute fibrils after division. It has a soft feeling, swelling, warmth, and has anti-pilling and abrasion whitening resistance. The present invention relates to a core-sheath type fibrillated fiber or fabric which is excellent and has a firmness and elasticity. [Constitution] As for the sheath component, one component has an intrinsic viscosity of 0.48 to
It is a low-viscosity polyester of 0.60 (component A), the other component is a polyester (component B) having higher solubility than component A, and the weight ratio of component A / component B is 2 /
A composite fiber having a shape in which both components are bonded together at 1 to 10/1, comprising a polyester having 32 or more layers, and having a core component comprising polyester, the sheath component of the core-sheath type composite fiber A core-sheath type fibrillated fiber or cloth having fine fibrils produced by dissolving and removing the B component therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent pilling resistance and abrasion whitening resistance, is a natural fiber-like material, and has a soft feeling, a swelling feeling, a warm feeling, and a firm and firm core / sheath. Type fibrillated fiber or fabric.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 47-9533 discloses that at least two kinds of components having different coloring degrees are formed in a single filament by performing at least six phases of different phase bonding-splitting. A super multi-layer filament in which the number of layers constituting an arbitrary cross section of a single filament is 64 or more, which are substantially continuous along the longitudinal direction of the filament to form a continuous thin layer and are joined to each other. Is disclosed. However, this publication only discloses the filament and does not describe the subsequent treatment. When this filament is used as it is for a woven or knitted fabric, only the coolness of the texture peculiar to polyester is emphasized, and the feeling of wearing is extremely poor. It was

In JP-A-2-277880, a polyester multi-filament yarn consisting of a polyester component having a low alkali solubility and a polyester component having a high alkali solubility is subjected to a fluid treatment to form a lube fluff. Then, a method of weaving using this yarn and then dividing by weighing with alkali is disclosed. However, in this method, since the fluid treatment is performed before the alkali reduction treatment, the process is complicated and the productivity is remarkably impaired.

Further, in this publication, a polyester obtained by copolymerizing a third component in an amount of at most 5 mol% is used as a polyester component having a low alkali solubility, and polyethylene glycol or sulfoisophthalic acid is used as a polyester component having a high alkali solubility. A copolymer is used. In the former case, using polyester in the normal viscosity range,
When fibrillated by chemical treatment such as alkali reduction treatment or mechanical treatment such as false twist and used in woven or knitted fabric, pilling or abrasion whitening becomes noticeable, and its application to clothing is limited. .

According to this publication, when a third component as a polyester component having a low alkali solubility is copolymerized in an amount of 5 mol% at most, an intrinsic viscosity (hereinafter referred to as [η]) is certainly true.
However, the modified polyester having such a viscosity cannot solve the problem of pilling or abrasion whitening. Moreover, this publication does not disclose at all the reason why a polyester obtained by copolymerizing the third component up to 5 mol% was selected as the polyester component having a low alkali solubility.

In Japanese Patent Publication No. 61-167079, [η] is a polyester having a small alkali solubility.
Although a polyester of 65 to 0.75 is used, even at a viscosity in this range, pilling or abrasion whitening is conspicuous and it is not practical.

In Japanese Patent Laid-Open No. 63-152460, a block polyester polyester obtained by copolymerizing a normal polyester as a polyester component having a small alkali solubility and a polyethylene glycol as a polyester component having a large alkali solubility. An example using is disclosed. This also uses normal polyester as one of the components, so pilling or abrasion whitening remains unsolved.

Japanese Unexamined Patent Publication (Kokai) No. 6-57621 discloses a method in which a composite fiber of polyester and a binder having high solubility is divided and bundled to form a polyester ester elastic yarn and a woven or knitted fabric. Has been done. However,
This also uses normal polyester as a polymer with low solubility, similarly pilling after fibrillation,
The problem of whitening wear arises.

The finely divided fibrils have a very fine single yarn denier, and when they are used in a woven or knitted fabric, pilling occurs, and their application to clothing and the like is significantly limited. Also, whitening due to abrasion becomes remarkable, and anti-pilling property,
There was hardly any excellent whitening of wear.

Various examples of using a low-viscosity polyester for imparting anti-pilling property have been proposed. For example, JP-A-53-130347 and JP-B-60-479.
No. 40 and Japanese Patent Publication No. 61-14259, [η]
An example using a low viscosity polyester having a value of less than 0.48 is disclosed. However, although the anti-pilling property can be certainly imparted with [η] in this range, from the viewpoint of workability, it is very difficult to industrialize a low viscosity polyester in this viscosity range.

Japanese Unexamined Patent Publication Nos. 54-38954 and 5
No. 4-38955, Japanese Patent Publication No. 60-52220, and Japanese Patent Publication No. 61-11329 disclose examples in which a third component is added to reduce the viscosity of polyester and to exhibit anti-pilling property. . In this case, it is described that [η] is in the range of less than 0.54, but this method involves the complexity of industrial production of adding the third component and leads to an increase in production cost. Moreover, these low-viscosity polyesters are used as a single polymer, which is different from the manifestation of the anti-pilling effect in our intended conjugate.

[0012]

DISCLOSURE OF THE INVENTION The present inventors have no problem of pilling or whitening of wear, and furthermore, the fine fibrils present on the surface layer of the fiber will make a soft feeling, a swelling feeling, and a warm feeling of span adjustment. I thought. First,
The method for producing fibrils is such that the single yarn denier after splitting becomes thin (1) In the cross section of the composite fiber, one component does not completely surround the other component, but both components are joined in layers. And the number of layers is at least 32
And (2) As a treatment method, a dissolution treatment by a known chemical treatment such as alkali reduction was performed. By adopting the structure as in (1), fibrillation can be achieved by simple treatment such as alkali reduction without performing complicated treatment during division. (3) In order to provide the anti-pilling property and abrasion whitening resistance that we have aimed for, we have decided to use the low-viscosity polyester conventionally used as a single polymer as the A component. In the present invention, a homopolyester having a reduced viscosity is used without adding the third component. Further, in the composite fiber, there is no example in which the low-viscosity polyester has been used so far, and as a result of diligent study on the appropriate viscosity range of the polyester and the spinning conditions, the low-viscosity polyester having the viscosity range of 0.48 to 0.60 is used. By doing so, anti-pilling property, abrasion whitening,
A composite fiber satisfying all the operability and the like was obtained. (4)
The cross section of the composite fiber was made into a core-sheath type. By doing this,
Although the sheath portion is fibrillated by the dissolution treatment, the core portion substantially remains even after the fibrillation treatment, so that a natural fiber-like texture is expressed, and a fibrillated fiber or fabric with firmness and elasticity is obtained. .

[0013]

The present inventors have completed the present invention as a result of intensive studies. That is, the present invention
In the sheath portion, one component is a low-viscosity polyester (A component) having an intrinsic viscosity of 0.48 to 0.60, and the other component is a polyester (B component) having higher solubility than the A component. / B component weight ratio is 2/1 to 10/1
And a composite fiber having a shape in which both components are bonded together, comprising polyester having 32 or more layers, and having a core portion made of polyester, wherein B in the sheath portion of the core-sheath type composite fiber is
It is a core-sheath type fibrillated fiber or cloth having fine fibrils formed by dissolving and removing the components.

The core-sheath type fibrillated composite fiber referred to in the present invention means that the core portion is made of polyester, the sheath portion is made of two kinds of polyester components having different solubilities, and the sheath portion has a cross section of a single filament. A composite fiber in which one component of one component does not surround the other component and both components are joined in a layered manner. However, a part may be enclosed as long as the object and effect of the present invention are not impaired. Specifically, as shown in FIGS. 1 and 2, a multilayer structure in which the A component and the B component of the sheath portion are alternately and continuously layered can be given. In such a multi-layer structure, the B component having a high solubility is completely dissolved and removed by the dissolution treatment and only fibrils of the A component are produced, or the B component is partially left and the A component is passed through the B component. The comrades are partially joined.

In the core-sheath type fibrillated composite fiber of the present invention, it is preferable that the multi-layer laminated structure of the A component and the B component of the sheath portion is uniformly continuous along the longitudinal direction of the filament, but a part thereof. May contain a discontinuous structure. A yarn having a uniformly continuous structure is preferable because it has good spinnability and drawing operability and does not give rise to defects after it is made into a product. In addition, fibrillation means that the B component of the sheath portion of the fibrillated composite fiber is completely dissolved and removed and only the A component is left, or the B component partially remains, and the A component is passed through the B component. It means that the comrades are in a partially joined form. Here, although it is preferable that the B component is completely dissolved and removed, even if a part of the B component remains, the effect of the present invention is sufficiently exhibited. In the present invention, this is called fibrillated fiber.
The present invention also includes a fibrillated fiber and a woven or knitted fabric made of the fibrillated fiber.

The dicarboxylic acid component used in the polyester having a low solubility (component A) constituting the sheath in the present invention includes terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and 1,5-naphthalenedicarboxylic acid. ,
4,4′-diphenyldicarboxylic acid, bis- (4-carboxyphenyl) sulfone, 1,2-bis (4-carboxyphenyl) ether, 1,2-bis (4-carboxyphenyl) ethane, diphenyl-p , P'-dicarboxylic acid, p-phenylenediacetic acid, diphenyl oxide-
P, p'-dicarboxylic acid, trans-hexahydroterephthalic acid, and ester-forming derivatives thereof such as alkyl ester, aryl ester, ethylene glycol ester and the like can be mentioned. Among them, useful terephthalic acid, 2,6-naphthalenedicarboxylic acid as a main component, and adipic acid, sebacic acid, azelaic acid, decamethylene dicarboxylic acid, and other fats as dibasic acid components copolymerizable with these aromatic dicarboxylic acids One or more kinds of group dicarboxylic acids and ester-forming derivatives thereof can be used within a limit of 10 mol%.

On the other hand, as the glycol component, ethylene glycol, 1,2-propylene glycol, 1,4-
Butanediol, trimethylene glycol, 1,6-hexanediol, 1,4-cyclohexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol -S and ethylene glycol, polyethylene glycol adducts thereof, diethylene glycol, polyethylene glycol and the like. Among them, useful ethylene glycol,
It is possible to use 1,4-butanediol as a main component, and at least one other copolymerizable ester-forming derivative as a main component, up to 10 mol% of the diol component.

The above polyester copolymer, for example, a dicarboxylic acid component containing terephthalic acid or 2,6-naphthalenedicarboxylic acid as a main component and ethylene glycol or 1,
An aromatic polyester composed of a glycol component containing 4-butanediol as a main component is produced by a known method.

Pigments, matting agents, optical brighteners, ultraviolet absorbers,
Various kinds of acid value inhibitors, antistatic agents and ether bond inhibitors such as organic amines and organic carboxylic acid amides may be used as required.

The [η] of the polyester is 0.48 to 0.
60, preferably 0.50 to 0.55. When [η] is less than 0.48, spinning and drawing operability are significantly deteriorated. On the other hand, when [η] is larger than 0.60, the anti-pilling property or the whitening of wear is remarkably deteriorated.

The highly soluble polyester (component B) constituting the sheath portion by the method of the present invention has a sulfonate group, for example, sodium 3,5-di (carbomethoxy) benzenesulfonate, 1,8- Di (carbomethoxy)
A compound such as sodium naphthalene-3-sulfonate or sodium 2,5-bis (hydroxyethoxy) benzenesulfonate or a known compound having a polyethylene glycol component was added and copolymerized during the production of the polyester. Examples include modified polyester and the like.

The ratio of component A and component B (hereinafter referred to as component A / component B) constituting the sheath is 2/1 to 10/1, preferably 3/1 to 5/1. A component / B component is 2 /
When it exceeds 1, not only does the amount of the polyester component having a large solubility become too large and an economically serious problem arises, but also the spinning and drawing operability deteriorates remarkably. Also, A component / B component is 10/1
When it is smaller, the amount of the highly soluble polyester component is too small so that fibrillation does not substantially occur.

It is necessary that the solubility of the component B is higher than that of the component A, and the solubility of the component B is at least 3 times or more, more preferably 10 times or more, particularly preferably 30 times or more. It has a sex. Here, the solubility may be a comparison in a 2% sodium hydroxide aqueous solution at 100 ° C., for example.

The polyester used as the core component in the present invention has a fiber-forming ability, is less soluble than the component B, and has the same solubility as the component A. There is no particular limitation. For example, the above polyester or the one obtained by copolymerizing the third component when forming the above polyester may be used.

The cross-sectional shape of the core-sheath type fibrillated composite fiber referred to in the present invention may be a known shape such as a round cross section, a triangular cross section, a Y cross section, a U cross section or a flat cross section for both the core and the sheath. The shape of the part is preferably a modified cross section such as a triangular cross section, a Y cross section, a U cross section, or a flat cross section from the viewpoint of easy fibrillation. Further, the shapes of the core portion and the sheath portion may be the same or different.

According to the present invention, the highly soluble polyester (component B) in the sheath portion of the fibrillated composite fiber is removed by the dissolution treatment. The dissolution treatment method and solvent are not particularly limited as long as they can efficiently dissolve the target polyester component, and examples thereof include alkali weight reduction treatment using an alkaline aqueous solution or the like. Examples of the alkali used in the alkali dissolution treatment include oxides, hydroxides and carbonates of alkali metal compounds (hereinafter referred to as alkali compounds), such as lithium hydroxide, sodium hydroxide, potassium hydroxide and hydroxide. Examples include cesium, rubidium hydroxide, sodium carbonate, potassium carbonate and the like. Among these, it is preferable to use sodium hydroxide, which has a low cost and a large elution ability.

The concentration of the alkaline compound varies depending on the type of the alkaline compound, the treatment conditions, etc.
The range is 1 to 20% by weight, preferably 1 to 10% by weight. The alkali reduction treatment is usually performed in a warm bath at 60 to 100 ° C or in steam at 100 to 150 ° C for 1 minute to 1 hour. The weight loss rate due to alkali weight loss is usually 40% by weight or less, preferably 10 to 30% by weight. When the weight loss rate exceeds 40% by weight, polyester having a small alkali solubility tends to be dissolved, and the mechanical properties of the fibrillated fiber are deteriorated. If the weight loss rate is less than 10% by weight, the fibrillation of the composite fiber of the present invention is not sufficiently performed. Further, regardless of before and after this treatment, there is no problem even if the joint surface is peeled off by mechanical refraction such as false twist.

The number of layers constituting an arbitrary cross section of the sheath of the present invention must be 32 or more, preferably 64 or more in total of A and B layers. When the number of layers is less than 32, good fibrils are not expressed and the desired texture cannot be obtained. Further, the single yarn fineness of the composite fiber after fibrillation is 0.
It is 1 denier or less, preferably 0.05 denier or less.

In the fibrillation by alkali reduction treatment or the like, it is not necessary that the B components of all filaments be uniformly and equally reduced, and the weight reduction rate may be different depending on the filament. That is, in the filament, there are mixed filaments in which the B component is completely dissolved and removed to form fibrils of only the A component, partially fibrillated, or hardly fibrillated. May be. These filaments differ in the degree of B component weight loss due to alkali weight loss treatment, and as a result,
After the fibrillation, the fluctuation of the single yarn denier between the filaments occurs. In order to develop a soft feeling, a swelling feeling, and a warm feeling in the natural fiber-like object which is the object of the present invention, it is preferable that there is such a variation in denier between filaments.

Regarding the relationship between the number of layers in the multilayer structure of the sheath portion and the number of stages (n) of the mixer, when the number of stages of the mixer is (n), the maximum number of layers is 2 ⁿ . However, the number of layers can be changed by changing the number (n) of stages of the mixer. For example, if the number of mixer stages (n) is 6, the maximum number of layers is 64, and if (n) is 7, the maximum number of layers is 128.
Can be Therefore, it is possible to form thinner fibrils by increasing the number of layers and thicker fibrils by decreasing the number of layers.

[0031]

As described above, in the present invention, a low-viscosity polyester is used as the polyester component having a low solubility of the sheath component, and a compound having a sulfonate group or polyethylene glycol is used as the polyester component having a high solubility. Since the modified polyester copolymerized with is used, pilling does not occur and abrasion whitening hardly occurs after fibrillating only the sheath portion by dissolution treatment such as alkali reduction. Further, by having a multi-layered structure and having 32 or more layers, fibrillation can be achieved only by a simple treatment such as alkali reduction, and the productivity is very good industrially. Further, since the core portion remains without undergoing fibrillation substantially, it is possible to obtain a fibrillated fiber or cloth having excellent elasticity and stiffness.

[0032]

The present invention will be described in detail with reference to the following examples. In the examples, "parts" means "parts by weight" unless otherwise specified, and "%" means "% by weight" unless otherwise specified. The intrinsic viscosity [η] was determined by a conventional method at 20 ° C in a mixed solvent of phenol / tetrachloroethane = 6/4. The melting point was determined from the endothermic peak of a differential scanning calorimeter (hereinafter referred to as DSC) manufactured by Rigaku Denki Co., Ltd. Further, the scanning electron microscope (hereinafter referred to as SEM) measurement was carried out with an Akashi scanning electron microscope manufactured by Akashi Seisakusho. The abrasion test was carried out by using a universal abrasion test manufactured by Shimadzu Corporation under a condition of 500 times and 1000 times under a load of 500 g. The anti-pill test was made by Daiei Kagaku Seiki Seisakusho.
5 hours, 10 hours, 2 using ICI pilling tester
The measurement was performed under the condition of 0 hours.

Example 1 (A) Polymerization step of PET component (A component) having low alkali solubility: 388 parts of dimethyl terephthalate, 248 parts of ethylene glycol, and 0.07 with respect to dimethyl terephthalate. %
Zinc acetate, 0.02% titanyl oxalate and 0.0
A mixture consisting of 1% antimony trioxide was added to 150-23
A transesterification reaction was carried out by heating at 0 ° C. for 120 minutes. Then, the temperature in the system was reduced to 275 ° C. in 30 minutes and the pressure in the system was reduced to 0.2 mmHg in 45 minutes, the reaction was continued for 60 minutes as it was, and the polymer was extruded into a cord and cut. After forming pellets having a size of 2.5 mmφ × 3 mm, the pellets were dried to a water content of 0.005%. The obtained polymer had an intrinsic viscosity [η] = 0.54 and a melting point of 259 ° C.

(B) Polymerization step of PET component (B component) having high alkali solubility 1500 parts of dimethyl terephthalate, ethylene glycol
1100 parts, 49.0 parts of sodium 3,5-dicarbomethoxybenzenesulfonate (5.0 mol% with respect to dimethyl terephthalate) and 1.2 parts of calcium acetate were added at 155 to 220 ° C. And heated for 130 minutes to carry out a transesterification reaction. Then, 0.6 part of antimony trioxide, 0.5 part of trimethyl phosphite, and 7.5 parts of titanium dioxide were added, and the temperature in the system was 30 minutes, and 27
0.2mm by reducing the pressure in the system to 5 ° C over 45 minutes
The reaction was continued for 60 minutes as Hg. The polymer was extruded into a cord shape and cut into pellets each having a size of 2.5 mmφ × 3 mm, and then dried to a water content of 0.005%. The viscosity of the obtained polymer was [η] = 0.54. The melting point was 256 ° C.

The number of stages (n) of the mixer is set to 6, and the ratio of the A component and the B component constituting the sheath portion is set to A component / B component = 3/1 by weight ratio, and the core component (A [Eta] = 0.65 polyester produced according to the method described in (1), and a spinning temperature of 280 with an extruder so that the weight ratio of the core portion to the sheath portion is 1/1. Melt spinning was performed at a temperature of ℃ and a winding speed of 1000 m / min. Then a magnification of 3.6
Roller heater at 85 ° C. at a stretching speed of 730 m / min.
Stretching with a plate heater set at 150 ° C,
A drawn yarn of 50d / 24f was obtained. According to the section observation of the undrawn yarn, the number of layers of the multilayer structure of the sheath portion was 64, which was theoretical.

Subsequently, the drawn yarn was tubular knitted with three yarns (total denier was 150 denier), and the mixture was alkali-treated with a 1% aqueous sodium hydroxide solution at a bath ratio of 1/100. Melting treatment temperature 98 ° C, melting treatment time 15 minutes, 20
Min, 25 min, 30 min, 35 min, 40 min, and the dissolution treatment of the polyester (component B) having a large alkali solubility in the sheath portion was performed. Next, S of the tubular knitted fabric after the alkali dissolution treatment
EM measurements were performed. As a result, it was confirmed that as the alkali dissolution treatment time became longer, fibrillation proceeded, and rayon-like fibrils were generated.

(C) Pilling Test Three fibrillated composite fibers before alkali dissolution treatment obtained by the above method were knitted into three plies and subjected to alkali dissolution treatment as described above, and then 5% owf Miketone polyester. High-pressure dyeing was carried out at 130 ° C. for 1 hour using a blue. Then, a pilling test was performed using the dyed tubular knitted fabric. As a result, almost no pilling was observed under any of the conditions.

(D) Abrasion whitening test Three fibrillated composite fibers before alkali dissolution treatment obtained by the above-mentioned method were knitted into three ply yarns and then at 130 ° C. using 5% owf miketone polyester blue. High-pressure dyeing took 1 hour. Then, an abrasion test was conducted using the dyed tubular knitted fabric. As a result, whitening due to abrasion was slight under any of the conditions.

Example 2 All steps were carried out as described in Example 1 except that the number of stages (n) of the mixer was changed to 5. Also in this case, when the section of the undrawn yarn was observed, the number of layers of the multilayer structure of the sheath portion was 32, which was the theoretical number. Also in this case, it was confirmed that as the alkali dissolution treatment time became longer, fibrillation proceeded and rayon-like fibrils were generated. Subsequently, a pilling test and a friction test were carried out as described in Example 1.
In this case, pilling did not occur under any condition, and whitening due to wear was slight.

Comparative Example 1 All steps were carried out in the same manner as in Example 1 except that the number of stages (n) of the mixer was changed to 3. Also in this case, when the section of the undrawn yarn was observed, the number of layers of the multilayer structure of the sheath portion was 8 which was the theoretical number. Also in this case, it was found that the fibrillation progressed as the alkali dissolution treatment time became longer, but the amount of fibrils generated was significantly smaller than that in Example 1 or Example 2. Furthermore, Example 1 or Example 2
It was found that pilling was more frequent than in the above and whitening due to abrasion was also noticeable.

Example 3 A low viscosity polyester (component A) was polymerized according to the method described in Example 1 to prepare a polyester having [η] = 0.50. All were carried out by the process described in Example 1 except that this polyester was used. Also in the section observation of this undrawn yarn, the number of layers of the multilayer structure of the sheath portion was 64, which was in accordance with the theory. Also in this case, it was confirmed that the fibrillation proceeded as the alkali dissolution treatment time became longer, and rayon-like fibrils were generated, the pilling was less likely to occur, and the whitening due to abrasion was slight.

Example 4 The procedure of Example 3 was repeated except that the number of mixer stages (n) was changed to 5. Also in the section observation of this undrawn yarn, the number of layers of the multilayer structure of the sheath portion was 32, which was theoretical. Also in this case, it was confirmed that as the alkali dissolution treatment time became longer, fibrillation proceeded and rayon-like fibrils were generated. In addition, pilling was small and whitening due to wear was slight.

Comparative Example 2 The procedure of Example 3 was repeated except that the number of mixer stages (n) was changed to 3. Also in the section observation of this undrawn yarn, the number of layers of the multilayered structure of the sheath portion was eight, which was the theoretical number. In this case as well, the fibrillation progresses as the alkali dissolution treatment time increases, but the amount of fibrils generated is significantly smaller than that in Example 3 or Example 4,
Furthermore, it was found that pilling was less likely to occur and whitening due to abrasion was remarkable.

Comparative Example 3 A polyester having [η] = 0.45 (component A) was prepared according to the method described in Example 1, and all the steps were carried out in the same manner as in Example 1 except that this polyester was used. Also in this case, fibrillation progresses as the alkali dissolution treatment time increases, and the amount of microfibrils generated is large.
Further, although pilling was small and whitening due to abrasion was slight, it was found that the operability was extremely poor and it was not suitable for practical use.

Comparative Example 4 A polyester having [η] = 0.63 (component A) was prepared according to the method described in Example 1, and all steps were carried out by the steps described in Example 1 except that this polyester was used. Also in this case, the fibrillation progresses as the alkali dissolution treatment time becomes longer, and the amount of fine fibrils is also good. However, it was found that pilling was noticeable and whitening due to abrasion was also noticeable. The above results are shown in Table 1.

However, the amount of fibrils generated in Table 1 means the amount of minute fibrils existing on the surface when SEM measurement is performed after subjecting three fibrillated composite fibers to tubular knitting and subjecting to alkali dissolution treatment. The sample with a large amount of fine fibrils and excellent texture was marked with ◯, and the sample with a small amount of minute fibrils was marked with x. In addition, the anti-pilling property means that three fibrillated composite fibers are knitted in a knitted yarn, the amount of alkali is reduced, the sample is subjected to high-pressure dyeing, and then a predetermined pilling test is performed to classify it, and a grade 4 or higher Is marked with ◯, grades 2-3 are marked with ∆, and grades below are marked with x. Further, the term "rubbing whitening resistance" means that three fibrillated composite fibers are knitted in a knitting yarn, the amount of alkali is reduced, and the sample is subjected to high-pressure dyeing.
A predetermined rubbing test was conducted, and white bleaching due to abrasion was barely noticeable with the naked eye, ◯ was slightly whitened due to abrasion, and Δ was markedly noticeable due to abrasion. In addition, the operability is the spinning and drawing operability, and the operability with good operability was marked with ◯, and the poor operability was marked with x.

[0047]

[Table 1]

[Brief description of drawings]

FIG. 1 is a drawing schematically showing a cross-sectional shape of a fibrillated composite fiber obtained in Example 1. When the number of stages (n) of the mixer is 6, the number of layers is theoretically 64. The white part of the sheath is a component having low solubility, and the black part is a component having high solubility. Also, the slanted line indicates the core. The ratio of the core portion to the sheath portion is 1: 1 (weight ratio).

FIG. 2 is a drawing schematically showing a cross-sectional shape of the fibrillated type composite fiber obtained in Example 2. When the number of mixer stages (n) is 5, the number of layers is theoretically 32. The white part of the sheath is a component having low solubility, and the black part is a component having high solubility. Also, the slanted line indicates the core. The ratio of the core portion to the sheath portion is 1: 1 (weight ratio).

Claims (2)

[Claims] 1. A sheath part, one component of which has an intrinsic viscosity of 0.48.
To 0.60 low viscosity polyester (component A), the other component is polyester having a higher solubility than component A (component B), and the weight ratio of component A / component B is 2 /
A composite fiber having a shape in which both components are bonded together at 1 to 10/1, comprising a polyester having 32 or more layers, and having a core portion made of polyester, the sheath portion of the core-sheath type composite fiber. 2. A core-sheath type fibrillated fiber, which has minute fibrils produced by dissolving and removing the B component. 2. A fabric made of the fiber according to claim 1.