JPH0827626A - Conjugated fiber and its production - Google Patents

Abstract

PURPOSE:To provide useful for obtaining a cloth which a lightweight fiber capable of being treated with an alkali without causing a slimy touch peculiar to a polyamide, excellent in water absorption, water, retention and water release and useful for obtaining a cloth suitable to a sportswear and a material for water absorbing rug. CONSTITUTION:This combined fiber is composed of 70 to 50wt.% polyamide and 30 to 50wt.% polyester and has <=90 ester amide exchange reactivity index (r). The polyester component constitutes a continuous layer exposed on the fiber surface [provided that the ester amide exchange reactivity index (r) is a value calculated from absorption peak heights (h1) and (h2) at 1635cm<-1> and 1165cm<-1> in an absorption spectrum obtained by measurement of infrared absorption spectrum according to the formula r=100h2/h1]. If a polyamide having >=60(meq/kg) amount of amino terminal group is used in melt blending 70wt.% to 50wt.% polyamide with 30 to 50wt.% polyester, the spinning process can be stably performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polyamide-based mixed fiber, which is suitable as a material for sports clothes, materials for water-absorbent rugs, etc., and a method for producing the same. More specifically, the present invention relates to a polyamide-based mixed fiber capable of providing a novel polyamide fiber which does not exhibit a slimy feeling peculiar to polyamide fiber due to alkali treatment, is lightweight, and is excellent in water absorption performance, water retention performance and water discharge performance, and a method for producing the same.

[0002]

2. Description of the Related Art As a method for removing the slimy feeling peculiar to polyamide fibers, 1 to 10% by weight of polyester is uniformly mixed and melted with polyamide, and the mixed fibers obtained by spinning and stretching are treated with an alkali metal hydroxide. Treated (hereinafter simply referred to as alkali treatment), 50 of polyester in the yarn
A method has been proposed in which at least 50% by weight is eluted to form fine streaky irregularities in the lengthwise direction of the fiber surface (Japanese Patent Publication No. 45-1646).

However, this method has a problem in that productivity is extremely poor due to frequent occurrence of yarn breakage during spinning and fluff yarn breakage during drawing. Further, there is a problem that the polyester in the yarn remains without being completely eluted and removed even by the alkali treatment, and the dyeing property of the polyamide is hindered. Japanese Unexamined Patent Publication No. 2-175965 proposes, for the purpose of solving such a problem, a method in which a polyester containing an organic sulfonic acid metal salt and a polyamide are mixed and spun. However, even with the proposal, the problem of spinnability could not be solved. Furthermore, since the fibers obtained by the above-mentioned prior art only have streak-shaped fine pores in the lengthwise direction, the texture of the fibers is silk-like, and the water-absorbing performance, water-retaining performance, and water-discharging performance of the object of the present invention. The performance could not exceed cotton.

[0004]

The object of the present invention is to eliminate the slimy feeling peculiar to polyamide fibers by alkali treatment, and to develop a novel polyamide fiber which is lightweight and has excellent water absorption performance, water retention performance and water discharge performance. It is to provide a mixed fiber and a manufacturing method capable of stably manufacturing the mixed fiber.

[0005]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems of the prior art, and as a result,
By using a polyamide-based mixed fiber with a specific ester amide exchange reaction index, the polyester component can be completely eluted and removed by alkali treatment, and it is completely different from the fiber with streak-like micropores obtained by the conventional technology. It has been found that a new polyamide fiber can be obtained. Further, in the production of such a mixed fiber, a production method has been found by which a polyamide having a specific amount of amino terminal groups is used to significantly improve yarn breakage during spinning and drawing, and the present invention has been completed.

That is, the present invention relates to polyamides 70 to 5
A mixed fiber composed of 0% by weight and 30 to 50% by weight of polyester and having an ester amide exchange reactivity index r of 9
A mixed fiber having a value of 0 or less and a polyester exposed on the fiber surface as a continuous phase (wherein the ester amide exchange reaction index r is an absorption spectrum obtained by measurement of an infrared absorption spectrum, 163
From the absorption peak height h1 of 5 cm ^{−1 and} the absorption peak height h1 of 1165 cm ⁻¹ , the formula: r = 100h2 / h
It is a value calculated by 1. ) And polyamide 70-
When 50% by weight and 30 to 50% by weight of polyester are melt-mixed, the amount of amino terminal groups is 60 (meq / kg)
A method for producing a mixed fiber is characterized by using the above polyamide.

The present invention will be described in more detail below. Polyamides used in the present invention include nylon 6, nylon 66, nylon 610, nylon 612, nylon 4
6, aliphatic polyamides such as nylon 12 are used. Further, these polyamides may be copolymers or copolymers of terephthalic acid, isophthalic acid and the like. Nylon 6 and nylon 66 are generally used. It is important to use these polyamides as specific end group-modified polyamides as described later in the production method.

The polyamide may contain additives such as an antistatic agent, a heat stabilizer, a flame retardant, a matting agent and a coloring agent, if necessary. On the other hand, as the polyester used in the present invention, terephthalic acid or its ester-forming derivative is a main acid component and ethylene glycol is a main alcohol component, polyethylene terephthalate (hereinafter abbreviated as PET), polybutylene terephthalate, polytetraene. Methylene terephthalate, polyethylene naphthalate, etc., or copolymers thereof are used. In general use, PET, polyester obtained by copolymerizing PET with polyalkylene glycol represented by polyethylene glycol, or organic sulfonic acid metal salt-containing polyester is used.

In the mixed fiber of the present invention, the mixing ratio of polyamide and polyester is 70 to 50% by weight of polyamide,
It is characterized by comprising 30 to 50% by weight of polyester. When the mixing ratio of the polyamide exceeds 70% by weight, the surface of the fiber becomes smooth and it becomes difficult to form the fine fibrils which are the object of the present invention. On the other hand, if the mixing ratio of polyamide is less than 50% by weight, the produced fibrils will be dispersed in the treatment bath or the washing bath during the alkali treatment, and it will be impossible to maintain a continuous fiber form.

The mixing ratio of polyamide is 65 to 50% by weight.
Then, after alkali treatment, the continuous fiber in which fine fibrils are aggregated, which is the object of the present invention, is obtained. In this mixing ratio, the polyamide has an average diameter of 2 μm or less and is finely dispersed in a stripe shape in the fiber axis direction. A more preferable mixing ratio of polyamide is 60 to 50% by weight. In this case, the polyamide fibrils are finely dispersed with an average diameter of about 1 μm to 0.5 μm. The state of such fine dispersion can be easily observed by an electron microscope by the method described later (FIG. 3). According to this observation, it is extremely difficult to observe the end portion of the fibril. From this, it can be said that in the mixed fiber of the present invention, the polyamide substantially forms continuous fibers having a stripe shape in the fiber axis direction.

The mixed fiber of the present invention must have an ester amide exchange reaction index r of 90 or less. The ester-amide exchange reaction index r is calculated by Seizo et al.
Volume 7 No. 302, 1970)) in reaction index proposed by, the absorption spectrum obtained by measuring the infrared absorption spectrum, the peak height h1 of amide absorption 1635 cm ^-1, the peak height in absorbance 1165 cm ^-1 It is a value calculated from h2 by the following equation.

R = 100h2 / h1 FIG. 1 shows an example of measuring the peak heights h1 and h2. The ester amide exchange reaction index r is an index indicating the sum of the ester-amide exchange reaction generated by the polyester-polyamide main chain exchange reaction and the ester-amide exchange reaction generated by the polyester-polyamide end reaction. is there. That is, the smaller the value of the ester-amide exchange reaction index r, the more the ester-amide exchange reaction progresses.

The ester-amide exchange reaction index r is 90.
Above that, it can be said that the polyamide and polyester are simply mixed or exist with almost no reaction. 1 and 2, the ester amide exchange reaction index r
The infrared absorption spectra of two examples with different values are shown. Figure 1
The ester amide exchange reaction index r is about 70, and FIG. 2 is about 95.

In the present invention, since the transesterification index r of the ester amide is 90 or less, the polyamide and the polyester are not simply mixed but chemically reacted and bonded. Such a chemical bond is
The mixed state of the polyamide and the polyester of the mixed fiber of the present invention and the alkali treatment property and the fibrous form of the polyamide fiber obtained by the treatment are suitable for achieving the object of the present invention. In the present invention, the ester amide exchange reaction index r is preferably 80 or less.

The mixed state of the polyester in the mixed fiber of the present invention is 70 to 50% by weight of polyamide and 30 to 50% by weight of polyamide, so that the polyester becomes a continuous phase and the fiber surface is present despite the excess polyamide. It is characterized by being exposed to. As a result, most or all of the polyester component can be dissolved and removed by the alkali treatment. The mixed fiber of the present invention has a dissolution removal rate of the polyester component of about 95% by alkali treatment.
The above is a major feature.

It is generally known that in the case of mixing incompatible polymers, components having a small mixing ratio form a so-called island phase. It is impossible to dissolve and remove all of the island phase components by alkali treatment. On the other hand, in the present invention, even though the proportion of polyester is less than 50% by weight, a continuous phase, so-called sea phase, is formed in the fiber, and since it is exposed on the fiber surface, it is almost completely treated by the alkali treatment. It can be dissolved and removed.

It is assumed that the characteristic mixed state of the present invention is closely related to the ester amide exchange reaction index r. The most preferable mixed state is a so-called co-continuous phase state in which the polyamide and the polyester are mixed as a whole and mixed so that the sea-island phase is hard to be identified. When the mixed fiber of the present invention is treated with an alkali, a fibril fiber consisting essentially of polyamide is obtained.

Dissolution of the polyester from the mixed fibers desirably removes about 90% or more of its mixing ratio. Further, when the dissolution and removal of the polyester from the mixed fiber is insufficient, the absorption of the dye is hindered during dyeing of the polyamide, resulting in a defect of light dyeing. Alkaline treatment
After knitting or weaving the fiber of the present invention to form a fiber structure, it is desirable to treat the fiber with a known alkaline aqueous solution. As the alkaline aqueous solution, sodium hydroxide, potassium hydroxide,
Known alkaline aqueous solutions such as lithium hydroxide and sodium carbonate are used.

FIG. 3 shows an electron micrograph of a fibile fiber obtained by alkali treatment when the mixing ratio of polyamide in the mixed fiber of the present invention is in a preferable range of 60 to 50% by weight. The fibril fiber obtained by subjecting the mixed fiber of the present invention to alkali treatment has 1735 peculiar to polyester.
No ester bond of cm ^-1 was observed, and the polyester component was completely dissolved and removed by the alkali treatment.

The fibril fiber obtained by subjecting the mixed fiber of the present invention to alkali treatment is an aggregate of polyamide fibril fibers having a diameter of about 2 μm or less, which are arranged substantially parallel to each other in the fiber axis direction. Such a fibril fiber does not exhibit the slimy feeling peculiar to ordinary polyamide for clothing, is lightweight, and is a fiber excellent in water absorption performance, water retention performance, and water discharge performance.

The manufacturing method of the present invention will be described below. In the production method of the present invention, polyamide 70-5
When 0% by weight and 30 to 50% by weight of polyester are melt-mixed, a polyamide having an amino terminal group amount of 60 (meq / kg) or more is used. When the amount of the amino terminal group is 60 (meq / kg) or more, the ester-amide exchange reaction index r reaches 90 or less by melt mixing with the polyester.

The amount of amino terminal groups of the polyamide can be easily adjusted by using a known amine type end-blocking agent at the stage of polymerizing the polyamide. For example, in general-purpose polyamides such as nylon 6 and nylon 66, diamines such as hexamethylenediamine and piperazine are used. The polymerization degree of the polyamide is not particularly limited as long as it is a fiber-forming one having a molecular weight of about 10,000 or more.

On the other hand, the polyester used in the production method of the present invention is not particularly limited as long as it is a fiber-forming one having a molecular weight of about 10,000 or more, but has a surface tension of 38 to 55 dyn for the purpose of enhancing affinity with polyamide. It is desirable to use polyester / cm. The surface tension of ordinary polyethylene terephthalate is 36 dyn / cm. The polyester having such a high surface tension can be obtained by copolymerizing polyester with polyethylene glycol, a metal salt of an organic sulfonic acid, or the like. In particular, when polyethylene terephthalate copolymerized with about 5 to 25% by weight of polyethylene glycol is used, the compatibility with polyamide is improved and the spinnability of the mixed fiber is improved. Furthermore, the diameter of the fibrils is reduced, and the extractability of the ester component is improved even in the alkali treatment, which is preferable.

In the production method of the present invention, a known extruder or static kneader is used to mix the polyamide and the polyester. In general, a method of chip-blending the both in advance and then melt-mixing using a uniaxial or biaxial extruder is adopted. In the melt mixing, it is desirable to carry out the mixing at a temperature of about 270 ° C. to 310 ° C. for about 3 minutes or more for the purpose of sufficiently reacting the polyamide and the polyester.

Known methods are used for the subsequent spinning and drawing after melt mixing. The spinning and stretching may be continuous, or may be once wound into a package and then stretched. Next, if necessary, known crimping or temporary twisting may be performed. Furthermore, without winding the fiber, high speed jetting
It may be formed into a laminated shape.

[0026]

The present invention will be described in more detail with reference to the following examples. In the examples, each measurement was performed by the following method. <Amino end group amount> 90% phenol with polyamide 4
It was dissolved at a concentration of wt% and neutralized by 0.02N hydrochloric acid by a conventional method to determine the amount of amino terminal groups.

<Surface tension> The surface tension of polyester is J
The wetting index was measured according to IS-K6768. <Observation of Mixed State> Regarding the fiber cross section, after freezing and cleaving the fiber in liquid nitrogen, the cleaved part was immersed in a 10 wt% sodium hydroxide aqueous solution at room temperature for about 20 hours to dissolve the polyester component. Then, after washing with water and drying, the cross section was observed with a scanning electron microscope at a magnification of 5,000 by a conventional method.

The fiber side surface was also treated and observed in the same manner. <Alkali Weight Loss Ratio> Fiber was used as a one-piece knitted fabric, and an immersion treatment was performed with a 5% by weight aqueous solution of sodium hydroxide at a bath ratio of 1: 100 at 95 ° C. for 30 minutes. From the weight measurement of the knitted fabric before and after the treatment, the alkali weight loss rate was calculated by the following formula.

Alkali weight loss rate (%) = {(A−B) / A} × 100 where A = Sample weight before weight reduction B = Sample weight after weight reduction <Water absorption rate> Sample after alkali weight reduction treatment is placed in water After soaking for 20 minutes, the water content of the sample after being dehydrated for 5 minutes with a Centru type centrifugal dehydrator at 3500 rpm was taken as the water absorption rate.

The cotton had a water absorption of 44% by weight in this measurement.

[0031]

Example 1 In this example, the effect of the amount of amino end groups of the polyamide used for melt mixing will be described. As polyamide, relative viscosity 2.65 (1% by weight in 95% sulfuric acid)
As shown in Table 1, nylon 66 having different amino terminal groups was used. As polyester, 51 parts of dimethyl terephthalate, 26 parts of polyethylene glycol having a molecular weight of 6000, and 23 parts of ethylene glycol were polymerized by a conventional method to give a polyethylene glycol copolymerization ratio of 2
5% by weight of polyester were obtained. The intrinsic viscosity (measured in orthochlorophenol at 1% by weight) of this copolyester was 0.65 and the surface tension was 51.

Chip blend spinning was performed with a mixing ratio of nylon 66 and copolyester of 60:40 by weight.
In spinning, the discharge rate per hole was 2.56 g / min, a spinneret having a hole diameter of 0.30 mmφ and 12 holes was used, and spinning was performed at a spinning temperature of 290 ° C. The spinnability was judged by the upper limit of the speed at which the winding speed was increased stepwise under the above-mentioned constant extrusion conditions and stable winding was possible without yarn breakage.

In this evaluation, when the maximum spinnable speed exceeds about 1000 m / min, the spinnability is good. As is clear from Table 1, No. 1 having an ester amide exchange reaction index r within the range of the present invention. 1 to No. 3 had good spinnability. Further, No. 1 in Table 1 having good spinnability. 1 to No. For 3, the winding speed is 700m /
The unstretched yarn wound up in minutes was stretched 2.2 times at 50 ° C. to obtain a mixed fiber of 180d / 12f. Table 1 shows the properties of the fibers obtained by subjecting the mixed fibers to one-piece knitting and then subjecting them to alkali treatment.

No. 1 in Table 1 1 to No. The mixed fiber of No. 3 treated with alkali reduction was an aggregate of microfibril fibers and had high water absorption.

[0035]

Example 2 In this example, the mixing ratio of polyamide and polyester is shown. No. 1 of the first embodiment. In the combination of Nylon 66 of No. 2 and copolyester, the mixing ratio of both was mixed at the ratio shown in Table 2 and spun. The spinnability was good at a winding speed of 700 m / min.
A mixed fiber was obtained by drawing in the same manner as in Example 1.

Table 2 shows the properties of the fibers obtained by subjecting the mixed fibers to one-piece knitting and then subjecting to alkali reduction treatment. As is clear from Table 2, when the mixing ratio of polyamide is higher than the range of the present invention, the removal of the polyester component becomes insufficient. Further, when the mixing ratio of the polyamide is less than the range of the present invention, it was difficult to maintain the shape of the knitted fabric because the fiber form after alkali treatment collapsed.

[0037]

Example 3 In this example, the effect of the surface tension of polyester used for melt mixing will be described. As the polyamide, nylon 66 having a relative viscosity of 2.65 and an amino end group amount of 68 is used, and as the polyester, those obtained by copolymerizing polyethylene glycol at the ratio shown in Table 3 in the same manner as in Example 1 are used. I was there.

The nylon and polyester chips were mixed at a weight ratio of 60:40, melt-mixed and spun in the same manner as in Example 1. Table 3 shows the spinnability and the characteristics of the fiber after the alkali treatment.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

EFFECT OF THE INVENTION The mixed fiber obtained by the present invention does not show a slimy feeling peculiar to polyamide due to alkali treatment, is lightweight, and is excellent in water absorption performance, water retention performance and water discharge performance. It is possible to provide a cloth foil suitable for materials for use. Further, according to the production method of the present invention, such useful mixed fibers can be stably spun.

[Brief description of drawings]

FIG. 1 shows an infrared absorption spectrum of a mixed fiber having an ester-amide exchange reaction index r within the range of the present invention.

FIG. 2 shows an infrared absorption spectrum of a mixed fiber having an ester-amide exchange reaction index r outside the range of the present invention.

FIG. 3 shows an electron micrograph of fibril fibers obtained by subjecting the mixed fiber of the present invention to alkali treatment.

Claims (4)

[Claims] 1. A mixed fiber comprising 70 to 50% by weight of polyamide and 30 to 50% by weight of polyester, wherein the ester amide exchange reactivity index r is 90 or less and the polyester is exposed as a continuous phase on the surface of the fiber. A mixed fiber characterized by: (However, ester-amide interchange reaction index r is the absorption spectrum obtained by measuring the infrared absorption spectrum, the peak height h1 of the absorption of 1635 cm ^-1, the peak height h2 in absorbance 1165 cm ^-1, the formula: r = 100h2 / h1). 2. A mixed fiber comprising 65 to 55% by weight of polyamide and 35 to 45% by weight of polyester, wherein the polyamide in the mixed fiber has a mean diameter of 2 μm or less and is dispersed in a streak shape in the fiber axis direction, and The mixed fiber according to claim 1, wherein the polyester is exposed as a continuous phase on the surface of the fiber. 3. Production of a mixed fiber, characterized in that, when 70 to 50% by weight of polyamide and 30 to 50% by weight of polyester are melt-mixed, a polyamide having an amino terminal group amount of 60 (meq / kg) or more is used. Method. 4. Nylon 6 or nylon 66 is used as the polyamide, and the surface tension of the polyester is 38 to 38.
The method for producing a mixed fiber according to claim 3, characterized in that polyester of 50 dyn / cm is used.