JPH11229237A - Sheath-core type conjugate yarn to be fibrillated - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheath-core type conjugate yarn capable of being fibrillated, having excellent spinnability, developing a fibril by alkali weight-loss treatment, providing a fabric such as woven fabric, knitted fabric, or the like, which causes neither pilling nor whitening by abrasion. SOLUTION: This sheath-core type conjugate yarn comprises a sheath part composed of two kinds of polyester components different in alkali solubility. A readily alkali-soluble polyester component (component B) 3 is dissolved and removed and a fine fibril is formed by an alkali weight-loss treatment. An alkali slightly soluble polyester component (component A) 2 constituting the sheath part satisfies the following conditions. (a) The intrinsic viscosity of the polymer in spinning is >=0.6. (b) The retention ratio of intrinsic viscosity before and after a wet heat treatment (in boiling water for 30 minutes) is 70-92%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a core-sheath type conjugate fiber having a sheath portion composed of two kinds of polyester components having different alkali-solubility. Is eluted and becomes a fibrillated fiber.

[0002]

2. Description of the Related Art Various types of fibrillated fibers have been proposed in order to improve the texture of the obtained woven or knitted fabric.
Above all, it is well known that a core portion of a core-sheath type conjugate fiber is formed from fibrils by subjecting a conjugate fiber composed of two components having different solubility to alkali reduction treatment.

[0003] As a core-sheath type conjugate fiber for producing fibrils by performing an alkali weight reduction treatment, Japanese Patent Application Laid-Open No. 2-2516
No. 73 discloses a composite fiber in which nylon and polyester are disposed in a sheath portion as two components having different solubility.
No. 73 discloses a conjugate fiber in which a readily alkali-soluble polyester and a normal polyester are disposed in a sheath portion.

[0004] Considering the spinnability, cost, color tone of the obtained fiber, and the like, the latter conjugate fiber in which an alkali-soluble polyester and ordinary polyester are disposed in a sheath portion is preferable. However, in the case of a composite fiber in which an alkali-soluble polyester and a normal polyester are arranged in a sheath portion only, when this fiber is used to form a woven or knitted fabric and fibrillated by alkali reduction treatment, pilling or abrasion whitening of the fibril portion is remarkably conspicuous. As a result, there is a problem that the use for clothing is limited.

[0005] To solve this problem, Japanese Patent Laid-Open Publication No.
No. 38 proposes a conjugate fiber using a low-viscosity polyester having an intrinsic viscosity [η] of 0.48 to 0.60 as a component of a sheath which is hardly soluble in alkali. However,
When this composite fiber is subjected to alkali weight reduction treatment to generate fibrils, the abrasion whitening of the resulting fibrillated fiber fabric is improved, but pilling is likely to occur, and yarn breakage occurs during spinning and stretching. However, there is a problem that the yarn operability is poor.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, has good spinnability, develops fibrils when subjected to an alkali weight reduction treatment, and obtains a woven or knitted fabric. It is an object of the present invention to provide a fibrilable core-sheath type composite fiber which does not cause pilling or abrasion whitening.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a sheath portion is made of a core-sheath type composite fiber composed of two kinds of polyesters having different alkali-solubility. By using a polyester whose viscosity is reduced by wet heat treatment as a soluble polyester component, it has sufficient strength during spinning, has good spinnability, expresses fibrils in the weight loss step, and fibrils in the wet heat treatment step such as dyeing. The inventors have found that the problem of pilling or abrasion whitening is solved by lowering the viscosity of the portion, and arrived at the present invention.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a sheath portion is composed of two types of polyester components having different alkali solubility, and the alkali-soluble polyester component (component B) is dissolved by performing alkali weight reduction treatment. A core-sheath composite fiber from which fine fibrils are removed,
Alkali poorly soluble polyester component (A
Component) satisfies the following requirements: a core-sheath type composite fiber that can be fibrillated. (A) The intrinsic viscosity of the polymer at the time of spinning is 0.6 or more. (B) The intrinsic viscosity retention rate before and after wet heat treatment (for 30 minutes in boiling water) is 70 to 92%.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The core-sheath type composite fiber capable of being fibrillated according to the present invention has a sheath portion composed of a polyester having a component B which is easily soluble in alkali and a component A which is hardly soluble in alkali.
Polyester whose viscosity is reduced by wet heat treatment. By subjecting the composite fiber to an alkali weight reduction treatment, the component B is dissolved and removed, and fine fibrils are formed.

[0010] The fibrillation means that the B component is completely dissolved and removed, leaving only the A component, or the B component partially remains, and the A components are partially joined to each other via the B component. It means that it will be in the form that was done.

The polyester of the component A must have an intrinsic viscosity of the polymer at the time of spinning of 0.6 or more. If the intrinsic viscosity of the polymer of the component A is less than 0.6, yarn breakage or the like is likely to occur at the time of spinning, operability is deteriorated, and the strength of the obtained yarn is reduced. The upper limit of the intrinsic viscosity of the polymer during spinning is preferably about 0.9. In addition, the intrinsic viscosity in the present invention is a value measured at 20 ° C. using an equivalent mixture of phenol and ethane tetrachloride as a solvent.

Further, the polyester of the component A must have an intrinsic viscosity retention of 70 to 92% before and after wet heat treatment (30 minutes in boiling water). 70% intrinsic viscosity retention before and after wet heat treatment
If it is less than 10, the strength of the fiber after the heat treatment is reduced. Also,
If the retention of the intrinsic viscosity before and after the wet heat treatment exceeds 92%, if pilling occurs, the resulting pilling does not fall off easily, so that the fabric made of this fiber is pilling or abrasion whitening.

Although the intrinsic viscosity after the wet heat treatment is not particularly limited, it is preferably 0.55 or more in order to prevent the strength of the yarn after the wet heat treatment such as dyeing from becoming too low. preferable.

Since the fiber of the present invention is a composite fiber, it is difficult to take out only the component A and measure the intrinsic viscosity before and after the wet heat treatment. Therefore, the intrinsic viscosity retention rate is a value obtained by spinning and stretching a yarn using the polyester containing only the component A, and performing wet heat treatment using the yarn as described below. The drawn yarn containing only the component A is treated in boiling water for 30 minutes, and the intrinsic viscosity [η] ₀ of the drawn yarn before the wet heat treatment and the intrinsic viscosity [η] ₁ of the drawn yarn after the wet heat treatment are obtained, and calculated by the following equation. Things. Intrinsic viscosity retention (%) = ([η] ₁ / [η] ₀ ) × 10
0

The polyester of the component A is such that the acid component is composed of terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4 naphthalenedicarboxylic acid and the like, and among them, terephthalic acid, 2,6-naphthalene Dicarboxylic acids are preferred, and a small amount of aliphatic dicarboxylic acids such as adipic acid, sebacic acid and azelaic acid may be copolymerized with these aromatic dicarboxylic acids.

On the other hand, as the glycol component, ethylene glycol, propylene glycol, 1,4-butanediol, trimethylene glycol, 1,6-hexanediol, 1,4-cyclohexanediol, neopentyl glycol and the like can be used. Especially, it is preferable to use ethylene glycol and 1,4-butanediol as main components.

Further, the polyester of the component A is used with respect to all the acid components of the polyester in order to obtain the intrinsic viscosity of the polymer and the intrinsic viscosity retention before and after the wet heat treatment.
The phosphorus compound represented by the following formula (1) is used in an amount of 0.5 to 1.5
Preferably, it is copolymerized by mol%.

[0018]

Embedded image

The compound represented by the formula (1) includes phosphoric acid, tri-n-butyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate and the like.
The phosphorus compound may be added at any stage before the polycondensation reaction between the acid component and the glycol component is started.

On the other hand, the polyester of the component B is a polyester which is easily soluble in alkali, and preferably has a solubility 5 times or more than that of the polyester of the component A, more preferably 15 times or more. Here, the solubility is a comparison based on the weight loss rate when treated in a 2% by weight aqueous sodium hydroxide solution at 100 ° C. for 30 minutes.

The polyester of the component B comprises the same acid component and glycol component as the polyester of the component A and has a sulfonate group, for example, 3,5.
And sodium di- (carbomethoxy) benzenesulfonate, 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, and copolymerized polyesters obtained by copolymerizing polyethylene glycol.

The polymer constituting the core is not particularly limited as long as it has a fiber-forming ability and has a lower alkali solubility than the polyester of component B.
It has the same solubility as the polyester of the component A, and it is preferable to use polyethylene terephthalate from the viewpoint of mechanical properties.

The above-mentioned polyesters of the A and B components in the sheath portion and the polymer in the core portion may be added with a pigment, a matting agent, a fluorescent whitening agent, an ultraviolet absorber during polycondensation or melt spinning.
An antioxidant, an antistatic agent, and an ether bond inhibitor such as an organic amine and an organic carboxylic acid amide may be added as required.

Furthermore, the fibrillable core-sheath type composite fiber of the present invention has a shape in which the A component and the B component constituting the sheath portion are alternately joined to at least 32 layers, and the weight ratio (A / B) is preferably 1/1 to 10/1. That is, the B component exists in the A component as an independent phase, and in particular, as shown in FIG. 1, in the cross section, one sheath component is joined in a shape that does not surround the other component. Preferably, the two components are continuously joined in a layer shape along the longitudinal direction of the filament. By adopting such a shape, the spinning and drawing operability is improved, and the defects of the product are reduced. The number of these layers is preferably 32 or more in total for the A and B layers in order to further improve the feeling of the light brushed tone.

In order to obtain such a conjugate fiber having a multilayer structure, the component A and the component B can be obtained by blending at the time of spinning. However, industrially, a method using a static mixer is preferable. . The relationship between the number of layers and the number of mixer stages (n) in the multilayer structure of the sheath portion is as follows. When the number of mixer stages is (n), the maximum number of layers is 2 ⁿ . Therefore, the number of layers can be changed by changing the number (n) of stages of the mixer. For example, if the number (n) of mixer stages is 6, the number of layers can be up to 64, and if (n) is 7, the number of layers can be up to 128. Therefore, when the number of layers is increased, thinner fibrils can be formed, and when the number of layers is reduced, thicker fibrils can be formed. However, the upper limit is preferably about 64.

Further, the weight ratio (A / B) of the component A and the component B constituting the sheath is 1/1 to 10/1, and more preferably 2/1.
/ 1 to 5/1. The ratio of the B component is A
If it is higher than the component, it elutes up to the fibrils during the alkali weight reduction, and the remaining fibrils are liable to fall off in the subsequent processing. On the other hand, when the ratio of the component A is higher than 10/1, the amount of eluted components is too small, and it becomes difficult to produce fine fibrils.

The cross-sectional shape of the core-sheath type conjugate fiber of the present invention may be any shape such as a round cross section, a triangular cross section, a Y cross section, a U cross section, and a flat cross section for both the core and the sheath. The shapes of the core and the sheath may be the same or different.
The thickness may be uneven in the length direction by changing the stretching conditions.

The alkali weight reduction treatment for forming fibrils in the core-sheath type conjugate fiber of the present invention includes a treatment using an aqueous alkali solution or the like. Examples of the alkali used include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like.
Among them, it is preferable to use sodium hydroxide which is inexpensive and has a large elution ability.

The concentration of such an alkali compound varies depending on the kind of the alkali compound, treatment conditions and the like, but is usually 0.1 to 20% by weight, preferably 1 to 10% by weight.

The alkali weight reduction treatment may be performed in the form of a yarn or a woven or knitted fabric, usually in a warm bath at 60 to 100 ° C. or in a steam at 100 to 150 ° C. for 1 minute to 1 minute.
Done in a time range. The weight loss rate is 40% by weight or less, preferably 10 to 30% by weight. Weight loss rate is 40
If the content is more than 10% by weight, the polyester of the component A also tends to be dissolved, and the mechanical properties and the like of the fibrillated fiber tend to be reduced. If the weight loss rate is less than 10% by weight, the composite fiber of the present invention cannot be sufficiently fibrillated. Regardless of before or after this treatment, there is no problem even if the bonding surface is peeled off due to mechanical refraction such as false twist.

The core-sheath type conjugate fiber of the present invention becomes a fibrillated fiber in which the fibril is generated in the sheath portion by the component B being completely or partially eluted by such weight reduction treatment. . In the alkali weight reduction treatment, the B components of all the filaments do not need to be reduced uniformly and to the same extent, and the weight loss rate may be different depending on the filament.

That is, in the filament, there is a mixture in which the B component is completely dissolved and removed to become a fibril of only the A component, or a filament which has been partially fibrillated. As a result, in these filaments, the single yarn denier between the filaments after fibrillation starts to fluctuate, whereby a soft feeling, a swelling feeling and a warm feeling are exhibited in a natural fiber-like.

[0033]

The present invention will be described below in detail with reference to examples. In addition, the measurement and evaluation in an Example were performed as follows. (A) Intrinsic viscosity [η] Measured by the method described above. (B) Retention rate of intrinsic viscosity after wet heat treatment Measured and calculated by the above method. (C) Strength Using alkali-weight-reduced yarn, use Orientic Tensilon Universal Tester RTC-1210, sample length
The measurement was performed at 500 mm and a pulling speed of 500 mm / min. (D) Abrasion whitening resistance The obtained fiber was plied in three yarns, knitted in a tube, and treated with a 1% by weight aqueous sodium hydroxide solution at a bath ratio of 1: 100 and a treatment temperature of 98 ° C., followed by alkali reduction treatment. The sample as a dye
Miketon PET Black RN-SF (Disperse dye manufactured by Mitsui Toatsu Chemicals) 4% owf, Dianix Black FB-FS (Disperse dye manufactured by Mitsubishi Chemical Industries) 12% owf, Kayaoryl Black R-ED (Nippon Kayaku Co., Ltd.) 8% owf, acetic acid as an auxiliary
Bath ratio 1: 100, temperature 125 ° C, 1 in dyeing bath containing 0.2cc / l
High-pressure staining was performed under the condition of time. Then, with a load of 500 g using a universal wear tester manufactured by Shimadzu Corporation
Measurement was performed under the conditions of 500 times and 1000 times. When the whitening due to abrasion was slight and inconspicuous to the naked eye, ○ was given when whitening due to abrasion was slightly noticeable, and x when whitening due to abrasion was noticeable. (E) Anti-pilling properties The obtained fiber was knitted into three yarns and knitted in a tube, subjected to the same alkali weight reduction treatment and dyeing as in (d), and then subjected to 5 steps using an ICI pilling tester manufactured by Daiei Kagaku Seiki Seisaku-sho, Ltd. The time was measured and a series was assigned. Grade 4 or higher was rated as 、, grades 2 and 3 as Δ, and grade 1 or lower as x. (F) Fibril generation amount The obtained fibers were knitted into three yarns and knitted in a tube, subjected to the same alkali reduction treatment as in (d), and the degree of generation of microfibrils existing on the surface was observed with a scanning electron microscope. When the amount of generated fine fibrils was large, it was evaluated as ○. (G) Operability Evaluated by the number of yarn breaks during spinning and stretching.糸 indicates that the number of yarn breaks per 24 hours was 1 or less, and X indicates that the number was more than 1 time.

REFERENCE EXAMPLE 1 [Polyester of component A (poorly soluble in alkali)] A polyester comprising terephthalic acid (TPA) and ethylene glycol (EG), which contains 3% by weight of phosphoric acid before the polycondensation reaction. Was added so that the phosphoric acid content was 0.85 mol% with respect to 1 mol of all the acid components. Thereafter, as a polycondensation catalyst, 2 per 1 mol of the total acid component was used.
× 10 ^-4 mol of antimony trioxide was added and polycondensation was performed to obtain a polyester A1. Polyesters A2 to A7 were obtained in the same manner as A1, except that the type and content of the phosphorus compound were changed as shown in Table 1. Table 1 shows the limiting viscosities of these polyesters A1 to A7. These polyesters A2 to A7 were spun and drawn according to a conventional method to obtain a drawn yarn having a single yarn fineness of 1.5 denier, and the intrinsic viscosity retention was measured. Table 1 shows the intrinsic viscosity retention rate and the intrinsic viscosity after the wet heat treatment. Since A4 contained too much phosphoric acid, it gelled during polymerization and could not be spun.

[Polyester of Component B (Easily Alkali-Soluble)] A polyester comprising TPA and EG, wherein 3,5-
A mixture obtained by mixing sodium di (carbo-β-hydroxyethoxy) benzenesulfonate and dimethyl 5-sodium sulfoisophthalate in a molar ratio of 60:40 to give an amount of 2.5 mol% and sodium acetate 15 × 10 ^-4 mol Was added to carry out polycondensation to obtain a polyester B.

[Polymer in core part] Polymerization was carried out in the same manner as in Component A except that phosphoric acid was not added, to obtain a polyester having an intrinsic viscosity of 0.69.

Examples 1 to 7 Comparative Examples 1 to 7 Core-sheath composite fibers having a cross-sectional shape as shown in FIG. 1 were produced using the components A and B and the polymer shown in Reference Example 1 for the core. At this time, the spinning temperature was set to 295 ° C. using a composite spinning device so that the ratio of the core portion to the sheath portion became 1/1 by weight.
Melt spinning was performed at a winding speed of 1000 m / min. Subsequently, the film was drawn with a heating roller (85 ° C.) at a magnification of 3.6 times and at a speed of 730 m / min, and heat-treated (150 ° C.) to obtain a 50d / 24f drawn yarn. Table 2 shows the number of layers of the sheath portion and the polymer ratio of the sheath portion (component A / component B) of the obtained composite fiber. Subsequently, the composite fiber is knitted into a tube, and a 1% by weight aqueous sodium hydroxide solution is used, and an alkali weight reduction treatment is performed under the conditions of a bath ratio of 1: 100 and a processing temperature of 98 ° C. so that the weight loss rate is about 20%. Was. Strength after alkali weight reduction treatment of the obtained composite fiber, abrasion whitening resistance, anti-pilling property, fibril generation amount,
Table 2 shows the operability measurement and evaluation results.

[0038]

[Table 1]

[0039]

[Table 2]

As is evident from Table 2, the core-sheath type composite fibers of Examples 1 to 7 can be obtained with good operability. When the fibers are subjected to an alkali weight reduction treatment, many fibrils are generated.
The knitted fabric obtained had a high evaluation of the anti-pilling property and the abrasion resistance whitening property. On the other hand, Comparative Example 1 had a low content of phosphoric acid of the component A and a high intrinsic viscosity retention after wet heat treatment, and Comparative Example 2 did not include the phosphorus compound in the component A. Since the intrinsic viscosity retention ratio before and after the wet heat treatment was high, both of them resulted in pilling and abrasion whitening when the resulting knitted fabric composed of composite fibers was subjected to alkali weight reduction treatment. In Comparative Example 3, since the intrinsic viscosity of the polymer at the time of spinning of the component A was too low, yarn breakage frequently occurred during spinning, and the operability was deteriorated, and a composite fiber could not be obtained.

[0041]

The core-sheath type conjugate fiber of the present invention is composed of a polyester having a low solubility by wet heat treatment as a polyester having a low solubility and a polyester having a high solubility. Can get well. In the core-sheath type composite fiber of the present invention, fibrils are generated only in the sheath part by the alkali weight reduction treatment, and the viscosity of the fibril part is reduced in a process such as dyeing. Hardly occurs. Furthermore, since the core remains substantially without fibrillation even after the alkali weight reduction treatment, it is possible to obtain a fibrillated fiber having excellent elasticity and firmness.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a fibrillable core-sheath type composite fiber of the present invention.

[Explanation of symbols]

 1 core 2 sheath (A component) 3 sheath (B component)

Claims (3)

[Claims] 1. A sheath comprising two kinds of polyester components having different alkali-solubility, and subjecting the alkali-reducing treatment to an alkali-soluble polyester component (B).
(Component) is dissolved and removed to form fine fibrils, wherein the fibril is characterized in that the alkali-insoluble polyester component (component (A)) constituting the sheath satisfies the following requirements. Core-sheath type composite fiber that can be converted. (A) The intrinsic viscosity of the polymer at the time of spinning is 0.6 or more. (B) The intrinsic viscosity retention rate before and after wet heat treatment (for 30 minutes in boiling water) is 70 to 92%. 2. The fibrilable core-sheath type conjugate fiber according to claim 1, wherein the polyester of the component A contains 0.5 to 1.5 mol% of the phosphorus compound represented by the formula (1) based on all the acid components. Embedded image 3. The composition according to claim 1, wherein the component (A) and the component (B) constituting the sheath portion are alternately joined to at least 32 layers, and the weight ratio (A / B) is 1/1 to 10/1. 3. The fibrilable core-sheath composite fiber according to 1 or 2.