JPH09310230A - Production of split type polyester conjugate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a split type polyester conjugate fiber, capable of stably melt-spinning the conjugate fiber at a high speed and having a small variation in dyeability. SOLUTION: This split type polyester conjugate fiber in which a slightly soluble component is divided into plural portions with an easily soluble component in the cross section of the fiber is melt-spun at a spinning speed of >=2500m/min. Therein, the easily soluble component is a polyester A containing a sulfonate salt group-having aromatic discarboxylic acid component in an amount of 1.3mol% based on the whole dicarboxylic acid component of the polyester A and further containing a polyalkylene glycol having an average mol.wt. of 1000-10000 in an amount of 5-15wt.%, and the slightly soluble component is a polyester B containing ethylene terephthalate units in an amount of >=80mol.% based on the whole constituting units. The components A and B satisfy the conditions of the following inequalities: [B]>[A], 2200>=[A]>=1000, and 2500>=[B]>=1200, wherein the [A] and [B] express the melt viscosities (dPa.s) of the polyesters A and B, respectively, at a temperature of 290 deg.C and at a shear speed of 1000s<-1> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of melt-spinning a splittable polyester conjugate fiber in which a difficult-to-eluting component is divided into a plurality of components in a cross section of the fiber at a high speed of 2500 m / min or more. It is about.

[0002]

2. Description of the Related Art Conventionally, an easily eluting component having an easily eluting property with respect to a specific solvent or a chemical substance and a hardly eluting component having a difficult eluting property have been used. A method widely available is one in which a split-type composite fiber in which the eluting component is divided into a plurality of parts is spun, and the easily eluting component is removed by a solvent or a chemical agent to obtain a fiber made of a difficult-eluting component with extremely fineness. It is being appreciated.

In particular, the easily-eluting component and the hardly-eluting component are composed of polyester-based components which are compatible with each other, and the hydrolysis of the easily-eluting component with alkali is made faster than that of the hardly-eluting component, thereby enabling division. Fiber has the following advantages and many proposals have been made so far. (1) The elution device, operation, chemicals, etc. are not special, there is no corrosiveness to the elution device, and it is safe and inexpensive. (2) Stable processing without problems such as yarn breakage or peeling between the easily-eluting component and the difficult-to-eluting component in the processes leading to the final product before elution treatment such as spinning, drawing, and knitting and weaving. You can (3) It has sufficient practical strength in the knitting and weaving process and the woven and knitted products.

For example, Japanese Patent Laid-Open Nos. 62-78213 and 1-
In 162825, polyethylene terephthalate as a difficult-to-dissolve component, a specific amount of an aromatic dicarboxylic acid component having a sulfonate group as a readily-dissolvable component, and,
A composite fiber using a polyester containing a specific amount of polyalkylene glycol is disclosed.

When such a composite fiber is formed into a fiber, 1500
If melt spinning is performed at a relatively low speed of m / min or less, there is no particular problem with the spinnability and the performance of the obtained fiber, but if the spinning speed is 2500 m / min or more to improve productivity, spinnability is improved. Is deteriorated and yarn breakage occurs in the spinning process, or the performance of the fiber composed of the difficult-to-dissolve component after elution varies, and in particular, the quality of the knitted fabric is deteriorated due to the variation in dyeability. there were.

[0006]

DISCLOSURE OF THE INVENTION According to the present invention, in a transverse cross section of a fiber, a split-type polyester composite fiber in which a difficult-to-dissolve component is divided into a plurality of easily-dissolvable components is stabilized at a spinning speed of 2500 m / min or more. It is intended to provide a method for producing a splittable polyester conjugate fiber, which can be melt-spun and can be obtained by subjecting the obtained fiber to an elution treatment to obtain a fiber composed of a component that is difficult to elute with little variation in dyeability. To do.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and its gist is as follows. In the cross section of the fiber, 2500m of split-type polyester composite fiber in which the difficult-to-dissolve component is divided into a plurality of easily-dissolvable components
In melt-spinning at a spinning speed of 1 / min or more, 1 to 3 mol% of the dicarboxylic acid component is an aromatic dicarboxylic acid component having a sulfonate group as an easily-eluting component, and has an average molecular weight of 1,000 to 10,000. Polyester A containing 5 to 15% by weight of polyalkylene glycol is used, and as a hardly-eluting component, polyester B having 80 mol% of all constituent units is ethylene terephthalate is used. A method for producing a splittable polyester conjugate fiber, characterized in that the following conditions are satisfied. [B]> [A] 2200 ≧ [A] ≧ 1000 2500 ≧ [B] ≧ 1200 where [A] and [B] are polyester A, respectively.
And the melt viscosity (dPa · s) of polyester B at a temperature of 290 ° C. and a shear rate of 1000 s ⁻¹ .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The composite fiber in the present invention has a form in which, in the cross-section of the fiber, the easily eluting component polyester A is divided into a plurality of hardly eluting component polyester B. FIG. 1 is a schematic cross-sectional view of a specific example of such a composite fiber.

In the present invention, it is preferable that the easily-eluting component polyester A has a dissolution rate in alkali more than 5 times faster than the hardly-eluting component polyester B. Therefore, in the polyester A, 1 to 3 mol% of the dicarboxylic acid component is an aromatic dicarboxylic acid component having a sulfonate group, and the average molecular weight is 1000 to
It is necessary to contain 5 to 15% by weight of 10000 polyalkylene glycol.

As the aromatic digalvonic acid component having a sulfonate group, 5-sodium sulfoisophthalic acid,
5-sodium sulfoterephthalic acid, 5-potassium sulfoisophthalic acid, 5-potassium sulfoterephthalic acid, 5
-Lithium sulfoisophthalic acid, 5-phosphonium sulfoisophthalic acid and the like can be mentioned.

When the copolymerization amount of the aromatic dicarboxylic acid component having a sulfonate group in the polyester A is less than 1 mol%, the dissolution rate in alkali becomes slow and the difference in the dissolution rate with the hardly soluble component can be increased. It gets harder. On the other hand, when the copolymerization amount exceeds 3 mol%, the spinnability at high speed is deteriorated and yarn breakage easily occurs in the spinning process.

The polyalkylene glycol contained in the polyester A dissolves in the polyester A with an alkali quickly to break the molecular chain of the polyester A and to generate voids on the surface to increase the surface area. Acts to accelerate the dissolution rate.

Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, copolymers of polyethylene glycol and polypropylene glycol, and the like.

Polyalkylene glycol has a molecular weight of 10
It must be between 0 and 10000. When the molecular weight is smaller than this, the glass transition temperature of the polyester A is lowered, so that fusion is likely to occur in the spinning step and the spinnability is deteriorated. Is not preferred. On the other hand, if the molecular weight is too large, the compatibility with the polyester becomes poor and it is difficult to make the polyester A uniformly contained.

When the content of the polyalkylene glycol is less than 5% by weight, the dissolution rate of the polyester A in the alkali becomes slow, while when it exceeds 15% by weight, the spinnability is deteriorated and the spinning process becomes difficult. Thread breakage easily occurs.

If necessary, the polyester A may be blended with an antioxidant such as a hindered phenol compound or a heat-resistant agent.

As the polyester B, which is the other component of the present invention, which is a poorly soluble component, it is necessary to use a polyester in which 80 mol% or more of all constituent units are ethylene terephthalate. In particular, polyethylene terephthalate composed of a terephthalic acid component and an ethylene glycol component is preferable, but a copolymerized third component may be used as long as the dissolution rate in alkali is not so increased. Specific examples of the copolymerization component include aromatic dicarboxylic acids such as isophthalic acid and naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid and azelaic acid, diols such as diethylene glycol and 1,4-butadiol, p- Examples thereof include hydroxycarboxylic acids such as hydroxybenzoic acid and β-hydroxyethoxybenzoic acid.

The polyester B may contain, if necessary, a matting agent such as titanium dioxide, an antioxidant such as a hindered phenol compound, a heat-resistant agent, a flame retardant, an antistatic agent, a coloring agent, and the like. Can be blended.

In the present invention, polyesters A and B are used in order to enable stable melt spinning and to make uniform the performance of the fiber comprising the hardly-eluting component after the elution treatment.
It is necessary that the melt viscosity of the above satisfies the conditions of the above formulas (1) to (3).

If the melt viscosity of polyester A is higher than the melt viscosity of polyester B when the requirements of the formula are not satisfied,
If the elongation of the composite fiber is set within an appropriate range, the draw ratio on the polyester B side in the drawing step will be outside the appropriate range. Variation easily occurs.

If the melt viscosity of the polyester A is smaller than the range defined by the formula, the melt viscosity is too low, resulting in poor spinnability and easy yarn breakage during the spinning process. On the other hand, when the melt viscosity of the polyester A is larger than the range of the formula, even if the condition of the formula is satisfied, the polyester B in the stretching step is
Since the draw ratio on the side is out of the appropriate range, the dyeability of the fiber made of the hardly-eluting component after the elution treatment tends to vary.

Further, if the melt viscosity of the polyester B is smaller than the range of the formula, the physical properties of the fiber composed of the hardly-eluting component after the elution treatment are deteriorated. On the other hand, when the melt viscosity of the polyester B is larger than the range of the formula, the melt viscosity is too high, and it becomes difficult to perform melt spinning by a usual method.

The intrinsic viscosities of the polyester A and the polyester B having the above melt viscosities are slightly different depending on the copolymerization substance and the amount of the copolymerization. However, the intrinsic viscosity of the polyester A is about 0.70 to 0.75. B is about 0.67
It is in the range of ~ 0.73.

The composite fiber can be manufactured by a conventional method. For example, a polyester spinneret designed to have a cross-sectional shape as shown in FIG. 1 can be obtained by sufficiently drying polyester A and B chips, and then using a general-purpose composite melt spinning machine table. A two-step method in which the yarn that is discharged and spun is cooled to apply an oil agent or the like, taken up at a speed of 2500 m / min or more, once wound, and then stretched and heat-treated to obtain a raw yarn, or a spinning process. There is a one-step method in which the discharged yarn is taken up by a heating roller, and is continuously drawn with a next heating roller without being wound into a raw yarn. In addition, in these steps, entanglement or the like can be added if necessary.

Next, after weaving and weaving the obtained raw yarn, weight reduction treatment is performed with an alkali such as an aqueous solution of sodium hydroxide,
Polyester A, which is an easily-eluting component, is eluted to obtain a fiber made of polyester B, which is a component having a fineness and is difficult to elute.

The weight reduction treatment is carried out, for example, by immersing the woven or knitted fabric in a sodium hydroxide aqueous solution having a concentration of 0.5% by weight at a temperature of 95 ° C.
This can be done by processing until a predetermined weight reduction rate is reached.

[0028]

[Function] Polyester A which is an easily-eluting component in the present invention
Has a relatively small amount of copolymerization of the aromatic dicarboxylic acid component having a sulfonate group, and therefore has excellent spinnability at high speed. Further, the polyalkylene glycol contained in a specific amount dissolves in the polyester A with an alkali quickly to break the molecular chain of the polyester A,
It has an action of generating voids on the surface to increase the surface area, etc., and exhibits a sufficiently high alkali dissolution rate as compared with polyester B which is a poorly-eluting component.

When a polymer having a different melt viscosity is compounded and discharged from the spinneret and thinned to form a fiber, the stress generated with respect to the take-up speed is not applied evenly to the fiber cross section, but rather the melt viscosity It is believed that more stress is placed on the higher polymer side. For this reason, the physical properties of the highly oriented unstretched conjugate fiber before stretching will reflect the molecular orientation of the polymer side with high melt viscosity, and the elongation of this conjugate fiber should be kept in an appropriate range during the stretching process. Then,
On the polymer side having a low melt viscosity, the draw ratio will be out of the proper range. In the present invention, since the melt viscosity of polyester B, which is a difficult-to-dissolve component, is made higher than that of polyester A, which is a readily-eluting component, the hard-to-dissolve component side is stretched at an appropriate stretch ratio, and after the elution treatment The dispersion of the physical properties and dyeing properties of the fiber composed of the poorly-eluting component is reduced.

[0030]

EXAMPLES Next, the present invention will be described in detail with reference to examples. The measurement and evaluation methods in the examples are as follows. (a) Intrinsic viscosity [η] Using an equal weight mixed solvent of phenol and ethane tetrachloride,
Measured in ° C. (b) Melt Viscosity A chip-shaped sample was dried under reduced pressure at 130 ° C. for 24 hours to remove water, and then measured using a flow tester (manufactured by Shimadzu Corporation, model CFT-500). (c) Alkaline dissolution rate ratio Polyester A and polyester B were individually melt-spun and drawn, and the drawn yarn obtained was subjected to weight reduction treatment at a temperature of 95 ° C for 15 minutes using an aqueous sodium hydroxide solution having a concentration of 0.5% by weight. Then, the respective alkali weight loss rates were obtained, and the ratio of the alkali weight loss rates was defined as the alkali dissolution rate ratio. (d) Dispersion of dyeability Ten samples of tubular knitted fabric were prepared and subjected to weight reduction treatment at a temperature of 95 ° C for 30 minutes using an aqueous solution of sodium hydroxide with a concentration of 0.5% by weight to completely remove easily-eluting components. Remove. Then, the weight-reduced tubular knitted fabric was dyed by a conventional method at a temperature of 130 ° C. for 60 minutes at a temperature of 130 ° C. using a dyeing solution of Terasil Navy Blue SGL (Ciba Geigy disperse dye) 1.0% owf and a bath ratio of 1:50. After washing and air-drying, the dyeability was judged as a standard sample by dyeing the tubular knitted fabric using ordinary polyethylene terephthalate drawn yarn of 70d / 48f under the same conditions, and the dyeability was similar. I asked. (The higher this ratio, the less variation in dyeability.)

Example 1 As polyester A, 5-sodium sulfoisophthalic acid (SIP-Na) was 2.5 mol% and polyethylene glycol (PEG) having an average molecular weight of 8000 was 13.3% by weight, and the intrinsic viscosity was 0.73 and the melt viscosity was 1550 dPa. s copolymerized polyethylene terephthalate, polyester B, polyethylene terephthalate (PET) with an intrinsic viscosity of 0.69 and a melt viscosity of 1650 dPa · s
Using a conventional composite spinning machine stand having a spinneret with 48 pores whose cross-sectional shape is designed so that polyester A divides polyester B into 8 as shown in FIG. 1 (d). , Spinning temperature 290 ℃, composite weight ratio A / B = 82/1
8, spun at a total discharge rate of 40 g / min, and wound at a speed of 3500 m / min while cooling and oiling to obtain 105d / 48f undrawn yarn. The alkali dissolution rate ratio of polyester A to polyester B was 8. Next, this unstretched yarn was drawn 1.56 times through a heating roller at 80 ° C, and then heat treated on a heat plate at 140 ° C and wound up,
70d / 48f drawn yarn was obtained.

Examples 2 to 4 and Comparative Examples 1 to 9 The procedure of Example 1 was repeated except that the polyester A and polyester B used were changed to those shown in Table 1.

With respect to the fibers obtained in the above Examples 1 to 4 and Comparative Examples 1 and 2, the results of measuring the variation in dyeability are summarized in Table 1. (In Comparative Examples 3 to 9, yarn breakage occurred frequently, and spinning was difficult.)

[0034]

[Table 1]

As is clear from Table 1, in Examples 1 to 4, stable spinning was possible at a high speed of 3500 m / min, and the fibers made of the polyester B, which was a poorly-eluting component after elution, had a variation in dyeability. It was few.

On the other hand, in Comparative Example 1, since the melt viscosity of polyester A is higher than that of polyester B,
In Comparative Example 2, since the melt viscosity of the polyester A was too high, high-speed spinning was possible for each, but the fibers made of the polyester B, which is a difficult to elute component after elution, had large variations in dyeability. . In Comparative Example 3, the melt viscosity of the polyester B is too high. In Comparative Example 4, the melt viscosity of the polyester A is too low. In Comparative Example 5, the melt viscosity of the polyester B is too low. In Comparative Example 6, the copolymerization amount of SIP-Na in Polyester A is too large, and in Comparative Example 7, the content of PEG in Polyester A is too large. Comparative Example 9 because the molecular weight of PEG is too high
However, since the molecular weight of PEG in polyester A was too low, yarn breakage occurred frequently when spinning at high speed, and a yarn could not be obtained.

[0037]

EFFECTS OF THE INVENTION According to the present invention, it is possible to stably melt-spin at a high speed of 2500 m / min or more, without yarn breakage or peeling between components, and by subjecting the obtained fiber to an elution treatment. A method for producing a splittable polyester conjugate fiber capable of obtaining a polyester fiber with less variation in dyeability is provided, and productivity can be improved and cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a specific example of a splittable polyester conjugate fiber according to the present invention.

[Explanation of symbols]

 A Polyester B which is an easily eluting component B B Polyester which is a hardly eluting component

Claims (1)

[Claims] 1. A melt-spinnable component when melt-spinning a splittable polyester composite fiber in which a sparingly-elutable component is divided into a plurality of parts in a cross section of the fiber at a spinning speed of 2500 m / min or more. As the polyester A, 1 to 3 mol% of the dicarboxylic acid component is an aromatic dicarboxylic acid component having a sulfonate group, and 5 to 15% by weight of a polyalkylene glycol having an average molecular weight of 1,000 to 10,000 is used. As a poorly soluble component,
A method for producing a splittable polyester conjugate fiber, wherein polyester B having 80 mol% of ethylene terephthalate is used, and the melt viscosities of polyesters A and B satisfy the following conditions. [B]> [A] 2200 ≧ [A] ≧ 1000 2500 ≧ [B] ≧ 1200 where [A] and [B] are polyester A, respectively.
And the melt viscosity (dPa · s) of polyester B at a temperature of 290 ° C. and a shear rate of 1000 s ⁻¹ .