JP2001089940A - Polyester-based splittable type conjugate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester-based splittable type conjugate fiber capable of providing a superfine fiber by carrying out an alkali weight reduction processing and imparting a soft touch feeling to a woven or a knit fabric while retaining a practical strength even after the weight reduction. SOLUTION: This conjugate fiber has a cross-sectional shape of the fiber split into plural pieces with a readily alkali-eluted component. The alkali weight reduction rate of a polyester B used as a split sparingly alkali-eluted component is <0.05 wt.%/min and the alkali weight reduction rate of a polyester A used as the readily alkali-eluted component is higher than the alkali weight reduction rate of the polyester B by >=10 times. The Young's modulus of the yarn after the splitting is <=35 g/D.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a fine fiber having good dyeability and alkali resistance and having a soft feeling, wherein a plurality of hardly-eluting components are used. The present invention relates to a polyester-based splittable conjugate fiber split into two.

[0002]

2. Description of the Related Art A splittable conjugate fiber in which a hardly-eluting component is divided into a plurality of components by a readily-eluting component in a fiber cross section is spun using an alkali with an easily-eluting component and a hardly-eluting component. A method for obtaining ultrafine fibers by removing easily eluting components with a solvent is widely used.

[0003] In particular, the easily-eluting component and the hardly-eluting component are composed of mutually compatible polyester-based components, and the rate of hydrolysis of the easily-eluting component by alkali is faster than that of the hardly-eluting component, so that the component can be separated. Fibers have been widely used so far due to the following advantages. (1) Alkaline weight reduction processing of polyester fiber is common, and the chemicals and dissolution equipment are not special, and are safe and inexpensive. (2) Before elution treatment such as spinning, drawing and weaving, stable processing is possible without troubles such as peeling between easily eluting components and hardly eluting components. (3) It has sufficient practical strength in the knitting and weaving process and the woven and knitted fabric. For example, JP-A-62-78213 and JP-A-1-260018 disclose a specific amount of copolymerization of an aromatic dicarboxylic acid component having a sulfonate group as polyethylene terephthalate as a hardly eluting component and a sulfonate group as an easily eluting component. A composite fiber using a polyester containing a specific amount of a polyalkylene glycol is disclosed.

[0004] Although ultrafine fibers can be produced by this method, it is difficult to obtain a soft feel which is most important by using ultrafine fibers because of the rigidity of polyethylene terephthalate.

[0005] Further, the ultrafine fibers from which the easily elutable components have been eluted and removed by alkali treatment have a large surface area as compared with ordinary single-fiber fineness fibers, so that they are greatly damaged by alkali and the yarn strength is reduced. There was a problem.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and it is easy to reduce the alkali content of a splittable polyester composite fiber divided into a plurality of portions by an alkali-eluting component. Providing a polyester splittable composite fiber that can quickly remove only the eluting component and perform stable alkali weight reduction processing, and the split ultrafine fiber has alkali resistance and a soft feel. Is a technical task.

[0007]

That is, the present invention relates to a polyester B used as a divided alkali hardly-eluting component in a conjugate fiber in which the cross-sectional shape of the fiber is divided into a plurality by an alkali-eluting component. Is less than 0.05% by weight / minute, and the weight loss rate of polyester A, which is used as an alkali-eluting component, is at least 10 times faster than the weight loss rate of polyester B. Has a Young's modulus of 35 g / D
A summary of a polyester splittable conjugate fiber characterized by the following.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

[0009] The conjugate fiber of the present invention has a form in which, in the cross section of the fiber, the hardly-eluting component is divided into a plurality by the alkali-eluting component.
FIGS. 1A to 1F are schematic cross-sectional views of a specific example of such a conjugate fiber. In FIG. 1, the hardly-eluting component B is divided into a plurality of components by the alkali-eluting component A, and each of the hardly-eluting components B is preferably 0.3D or less ultrafine fiber after the division.

In the present invention, the divided polyester B has an alkali weight loss rate of less than 0.05% by weight / minute, and the polyester A used as the alkali-eluting component has an alkali weight loss rate of the polyester B. It is necessary that the alkali weight loss rate of the polyester B, which is a divided component, is at least 10 times faster than that of the polyester A, which is an easily eluting component, than the speed. The upper limit of the alkali weight loss rate of the polyester A is 30% of the alkali weight loss rate of the polyester B.
About twice is preferable.

In the case of obtaining ultrafine fibers from splittable conjugate fibers, it is usually necessary to carry out a weight reduction treatment quickly in a short time in consideration of alkali damage to the ultrafine fibers.
Therefore, the difference between the weight loss rates of the polyester A and the polyester B is increased as much as possible. However, by setting the rate of weight loss of polyester B to less than 0.05% by weight / minute, which is an extremely low rate for polyester, it is possible to approach the rate of weight loss of polyester B to polyester A by up to about 1/10. It is assumed that. When polyester B, such as polyethylene terephthalate (hereinafter abbreviated as PET), whose alkali weight loss rate exceeds 0.05% by weight / minute is used as the polyester B, the ultrafine fibers divided during the alkali treatment have a large damage. Therefore, in order to quickly perform the weight reduction treatment time, a condition of about 1/40 to 1/200 times the alkali weight reduction rate ratio of polyester B to polyester A is adopted. Further, when the alkali weight loss rate of the split polyester B exceeds 0.05% by weight / minute, or the alkali weight loss rate of the split component polyester B exceeds 1/10 times the polyester A of the easily eluting component. Since the alkali hydrolysis rate of both components is too fast, the rate of weight loss of not only polyester A but also polyester B cannot be controlled, and it is difficult to control the target weight loss rate, and the yarn after alkali weight reduction has a uniform fineness. , And the cross-sectional shape is lost.
Therefore, it is important that the polyesters A and B have the following structures.

First, as the polyester A, it is preferable to use a polyester mainly composed of an ethylene terephthalate unit from the viewpoint of alkali weight loss and spinnability. In order to increase the alkali weight loss rate, it is preferable that the dicarboxylic acid component is copolymerized with an aromatic dicarboxylic acid component having a sulfonate group, and the amount is 2 to 20% by weight. Further, those containing a polyalkylene glycol having an average molecular weight of 1,000 to 10,000 are preferred. Polyalkylene glycol is dissolved in polyester A as soon as possible with an alkali to form polyester A.
It acts to increase the dissolution rate by cutting the molecular chain of, and increasing the surface area by generating voids on the surface.

The aromatic dicarboxylic acid component containing a sulfonate group includes 5-sodium sulfoisophthalic acid, 5-sodium sulfoterephthalic acid, 5-potassium sulfoisophthalic acid, 5-potassium sulfoterephthalic acid, and 5-lithium sulfoisophthalic acid. Examples thereof include acids and the like, and 5-sodium sulfoisophthalic acid is particularly preferable. The copolymerization amount is appropriately selected depending on the difference in the alkali weight reduction rate between the polyester A and the polyester B.
The range of 3.0 mol% is preferable, and it is preferable to minimize the copolymerization amount in terms of spinning operability and cost.

Next, it is important that the polyester B is excellent in dyeing properties, alkali resistance, light resistance and dimensional stability and has an excellent soft feeling after splitting.
Polyester B alkali weight loss rate is 0.05% by weight
/ Min, and the Young's modulus of the yarn obtained after splitting of the splittable conjugate fiber must be 35 g / D or less. The method for this is not particularly limited, but it is preferable to use polytrimethylene terephthalate (hereinafter abbreviated as PTT) as a polyester that can satisfy both conditions.

The PTT may contain a small amount of a copolymer component. Examples of the copolymer component include aromatic dicarboxylic acid components such as 5-sodium sulfoisophthalic acid, isophthalic acid, phthalic anhydride and naphthalenedicarboxylic acid. , Adipic acid, sebacic acid and other aliphatic dicarboxylic acid components, ethylene glycol, diethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, alkylene oxide adducts of bisphenol A, alkylene oxide adducts of bisphenol S, etc. And a hydroxycarboxylic acid component such as 4-hydroxycarboxylic acid and ε-caprolactone. Furthermore, additives, matting agents, pigments, and the like for the purpose of imparting functions such as antistatic, flame retardant, light resistance, and antifouling properties may be added to the polymer.

[0016]

The polyester splittable conjugate fiber of the present invention is characterized in that, when subjected to alkali weight reduction treatment, only the easily leasable component is rapidly dissolved and removed, and the strength of the yarn after splitting into ultrafine fibers is small, and the polyester splittable conjugate fiber has a small strength. This makes it possible to impart a soft texture to the surface. This is because, by using PTT as polyester B, which is a hardly eluted component that is divided into a plurality, the Young's modulus of the fiber after division is reduced,
This is because fibers having an excellent soft feeling can be obtained. In addition, since the alkali resistance is extremely high, it is possible to reduce the alkali weight loss rate of the polyester A, which is an easily elutable component, and it is possible to reduce the content of a component for accelerating the alkali weight loss rate.

[0017]

Next, the present invention will be described in detail with reference to examples. Note that the measurement and evaluation of various characteristic values in the examples are as follows.
The procedure was as follows. (A) Strong elongation After knitting the conjugate fiber and performing refining at 60 ° C. for 20 minutes, a 25% alkali weight reduction treatment is performed by the method (b) described later, and then the knitted tube is unraveled. Using a Tensilon Universal Tester Model RTC-1210 manufactured by Orientic, a 50 cm sample was measured by a tensile test at a speed of 50 cm / min. (B) Alkali weight loss rate The alkali weight loss rate of each polyester is 75D / 36f
Of the drawn yarn is treated with a sodium hydroxide aqueous solution having a bath ratio of 1:50 and 10% by weight at a treatment temperature of 70 ° C. and a temperature of 5,1.
After treating for 0 and 20 minutes, the alkali weight loss rate at each weight loss time was calculated by the following formula, and the average value of the alkali weight loss rate at each time was taken as the alkali weight loss rate of the polyester. Alkali weight loss rate (% by weight / min) = [(AB) / A ×
100] / t A: Weight of tubular knitted fabric before weight reduction (g) B: Weight of tubular knitted fabric after weight reduction (g) t: Processing time (minutes) for alkali weight loss. (C) Texture The texture of the tubular knitted fabric used in (a) after the alkali weight loss treatment was evaluated by the following sensory test by 10 panelists. As an object of comparison, a judgment was made based on a difference in texture between the drawn yarn obtained in Comparative Example 1 and the tubular knitted fabric.・ ・ ・: Eight or more out of 10 evaluated as softer than the comparison. Δ: 4 to 7 out of 10 persons were evaluated as being softer than the comparison object. X: Three or less out of 10 persons were evaluated as being softer than the comparison object. ○ Only the evaluation of the tubular knitted fabric in the judgment was regarded as the passing point of the texture.

EXAMPLE 1 As polyester A, 0.5 mol% of 5-sodium sulfoisophthalic acid (SIP-Na) and 3.0% by weight of polyethylene glycol (PEG) having an average molecular weight of 8,000 were copolymerized to have an intrinsic viscosity of 0.1%. As the copolymerized PET 72 and the polyester B, PTT having an intrinsic viscosity of 0.92 was used, and the cross-sectional shape of the yarn was such that the polyester A divided the polyester B into eight as shown in FIG. Using a designed spinneret having 48 holes, spinning is performed at a spinning temperature of 270 ° C., a composite weight ratio of polyester A / B of 20/80, and a discharge rate of 31 g / min.
The yarn was wound at a speed of 1 minute and a highly oriented undrawn yarn of 110D / 48fil was collected.

Next, this highly oriented undrawn yarn is drawn 1.50 times through a heating roller at 70 ° C., and further heat-treated on a heat plate at 130 ° C. to obtain a 75D / 48 film.
Was obtained.

Example 4 As the polyester A, 2.0 mol% of SIP-Na and 14% by weight of PEG having an average molecular weight of 6000 were copolymerized to form a copolymerized PET having an intrinsic viscosity of 0.70. Using a PTT of 92 and a spinneret having 72 holes designed so that polyester A divides polyester B into four as shown in FIG. Temperature 270 ° C, polyester A /
Spinning at a composite weight ratio of B of 15/85 and a discharge rate of 32 g / min,
While cooling and applying an oil agent, the film was wound at a speed of 2800 m / min, and a highly oriented undrawn yarn of 110D / 72fil was collected.

Next, the highly oriented unstretched yarn is stretched 1 to 52 times through a heating roller at 68 ° C., and further heat-treated on a heat plate at 130 ° C. to obtain a 75D / 72 film.
Was obtained.

COMPARATIVE EXAMPLE 1 As polyester A, 2.5 mol% of 5-sodium sulfoisophthalic acid (SIP-Na) and 12.0 wt% of polyethylene glycol (PEG) having an average molecular weight of 8,000 were copolymerized. 72 copolymerized PET, polyester B
As shown in FIG. 1 (d), a spinneret having 48 holes is designed so that polyester A divides polyester B into eight pieces as shown in FIG. At a spinning temperature of 290 ° C., a composite weight ratio of polyester A / B of 80/20, and a discharge rate of 38 g / min., While cooling and applying an oil agent, winding at a speed of 3500 m / min. A highly oriented undrawn yarn was collected.

Next, the highly oriented unstretched yarn was stretched 1.55 times through a heating roller at 80 ° C., and further heat-treated on a heat plate at 150 ° C. to obtain a 75d / 48f stretched yarn. .

Comparative Example 2 A drawn yarn was obtained in the same manner as in Comparative Example 1 except that the compositions of polyester A and polyester B were changed as shown in Table 1.

Examples 2-3 and Comparative Example 3 Except that the composition of polyester A was changed as shown in Table 1,
In the same manner as in Example 1, a drawn yarn was obtained. Table 1 also shows the evaluation results of the drawn yarns.

[0026]

[Table 1]

In Examples 1 and 2, the polyester A was subjected to SIP.
Although the content of PEG and PEG is low, the weight loss rate is slow as an alkali-soluble polymer, but the PTT is used for the polyester B, so the alkali weight loss rate ratio between the polyesters A and B is large, The weight loss splitting was good. In addition, since polyester B has good alkali resistance, the decrease in strong elongation after the alkali weight reduction treatment of the conjugate fiber was small. Also, since PTT is used, the Young's modulus of the yarn is low, and the texture of the tubular knitted fabric after weight reduction splitting is softer than that of the tubular knitted fabric using PET for polyester B. Was. In Examples 3 and 4, the rate of alkali weight loss of polyester A was reduced in Examples 1 and 2.
Since a polymer that is faster than that used is used, it is possible to shorten the alkali weight loss time. Polyester B
Since PTT is used, the cross-sectional shapes after weight loss are different in Examples 3 and 4, but the decrease in strong elongation after weight loss is small,
The texture of the knitted fabric was soft.

On the other hand, in Comparative Example 1, the alkali weight loss rate ratio between the polyester A and the polyester B was large, and the decrease in the elongation after the alkali weight loss treatment was small. However, since the polyester B was PET, the Young's modulus was higher than that of the examples, so that the texture of the tubular knitted fabric after the weight reduction was hard.

In Comparative Example 2, the rate of alkali weight loss of the polyester B was high, and the rate of weight loss of the polyester B as well as the polyester A during the alkali weight loss treatment of the conjugate fiber was high. Further, as for the weight-reduced split fiber, since the weight loss of the polyester B progressed, a part of the undivided fiber remained at a weight reduction rate of 25%, and SIP copolymerized PET was used. The texture of the tube knitted fabric became firmer than that.

In Comparative Example 3, although the rate of weight loss of polyester B was somewhat slow, the rate of weight loss of polyester A was also slow, so that the alkali weight loss time was prolonged and the decrease in strong elongation was large. Further, with respect to the weight-reduced split fiber, since the weight of the polyester B was reduced, a part of the undivided yarn remained at a weight reduction rate of 25%. Further, polyester B is P
Although TT was used, the texture of the tubular knitted fabric became firm due to the remaining unsplit fibers.

[0031]

The woven or knitted fabric using the polyester-based splittable conjugate fiber of the present invention can exhibit a soft texture by performing alkali weight reduction processing, and the strength of the yarn divided by weight reduction processing. The decrease is also small.

[Brief description of the drawings]

FIGS. 1 (a) to 1 (f) are schematic cross-sectional views showing specific examples of a splittable polyester-based composite fiber of the present invention.

[Explanation of symbols]

 A Polyester A of easy-eluting component B Polyester B C of low-eluting component Hollow portion

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L031 AA18 AA19 AB09 CA01 DA01 DA05 DA11 4L041 AA08 AA15 AA19 AA20 AA25 BA03 BA04 BA05 BA14 BA42 BC20 BD14 CA08 CA16 DD01 DD11 DD15 EE06 EE15 EE20 4L045 AA05 BA03 BA21 CA25 CA29 CB13 DC03

Claims (2)

[Claims] 1. A composite fiber in which the cross-sectional shape of a fiber is divided into a plurality of parts by an alkali-eluting component, the polyester B used as the divided alkali-eluting component has an alkali weight loss rate of 0.05% by weight. / Min, and the alkali weight loss rate of the polyester A used as the alkali-eluting component is 10 times or more faster than the alkali weight loss rate of the polyester B, and the yarn after splitting has a Young's modulus of 35 g / D or less. A polyester splittable composite fiber characterized by the above-mentioned. 2. The polyester-based splittable conjugate fiber according to claim 1, wherein the polyester B used as the hardly-eluting component is polytrimethylene terephthalate.