JPH06207322A - High-shrinkage conjugate fiber and its production - Google Patents

Abstract

PURPOSE:To provide a conjugate fiber producible on an industrial scale in high productivity, exhibiting the characteristics of nylon 6 as well as a saponified ethylene-vinyl acetate copolymer and having excellent feeling and heat- shrinkability. CONSTITUTION:The objective conjugate fiber contains a mixture of a saponified ethylene-vinyl acetate copolymer with 0.5-10wt.% of polyethylene as a core component and nylon 6 as a sheath component and has a core/sheath weight ratio of 7/3-3/7, a hot-water shrinkage of >=17% and a thermal shrinkage stress of >=0.37g/d.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a highly shrinkable composite fiber suitable for clothing, which comprises a saponified product of ethylene / vinyl acetate copolymer mixed with polyethylene as a core component and nylon 6 as a sheath component, and its production. It is about law.

[0002]

2. Description of the Related Art Polyamide fibers have excellent texture, dyeability, and strength / elongation characteristics and are widely used for clothing, but they do not have sufficient performance depending on the application.

For example, by using a polyamide fiber having a high shrinkage ratio of hot water and a high heat shrinkage stress, a fabric having appropriate tension, waist, resilience, and swelling can be obtained by post-processing. No polyamide fiber has been developed.

On the other hand, copolymers of vinyl acetate with olefins such as ethylene and propylene have excellent hydrophilicity and antistatic property, and have a texture similar to natural fibers such as cotton and hemp. give. In addition, saponified ethylene / vinyl acetate copolymer with a high ethylene content (hereinafter abbreviated as EVA)
Is known to give fibers with high heat shrinkage stress.
However, these copolymers do not have hot water resistance, and those whose components are exposed on the fiber surface cannot be put into practical use unless they are subjected to hot water treatment such as acetalization.

JP-B-54-38663 discloses that a hydrophobic thermoplastic resin such as polyamide or polyester is used as a sheath component,
A composite fiber having an improved texture has been proposed by utilizing the fact that the core component polymer has a large water-absorption swelling property by using a hydrophilic olefin-modified polyvinyl alcohol as a core component. In addition, Japanese Patent Publication No. 54-32874 proposes to obtain a woven fabric with an improved texture by subjecting this composite fiber to strong twisting and utilizing the restoring stress resulting from the hot water swelling force. However, in these fibers, since a polyvinyl alcohol-based copolymer having a low olefin content is used as a core component in order to improve hydrophilicity, melt spinning is difficult and, at the same time, the strength of the fiber is significantly decreased. Also, it does not have high heat shrinkage stress.

Further, Japanese Patent Laid-Open No. 4-327212 discloses E
A composite fiber having a high heat shrinkage stress in which VA is a core component and polyamide is a sheath component has been proposed. However, this composite fiber has a problem in that EVA is gelated by heat during melt spinning, resulting in poor spinnability. Although gelation of EVA can be suppressed to some extent by using a spinning device that reduces the amount of heat applied to EVA, the cost of the device increases, and in the case of composite spinning with nylon 6 having a higher melting point than EVA, EVA There was a limit to the suppression of gelation.

[0007]

DISCLOSURE OF THE INVENTION The present invention can be produced industrially with high productivity, and has excellent texture, dyeability, high elongation property and the like of nylon 6 fiber and high fiber of EVA. Taking advantage of the property of heat shrinkage stress,
An object of the present invention is to provide a composite fiber having a good texture and heat shrinkage property and a method for producing the same.

[0008]

The present invention is intended to solve the above-mentioned problems, and its gist is as follows. (1) Composite fiber in which saponified ethylene / vinyl acetate copolymer is mixed with 0.5 to 10% by weight of polyethylene as a core component and nylon 6 is a sheath component, and the core-sheath weight ratio is 7/3 to 3/7. And the hot water shrinkage is 17% or more, and the heat shrinkage stress is
Highly shrinkable conjugate fiber characterized by being 0.37 g / d or more. (2) A high-shrinkage composite characterized by melt-spinning a composite fiber comprising a saponified ethylene / vinyl acetate copolymer blended with polyethylene as a core component and nylon 6 as a sheath component, and then hot drawing. Fiber manufacturing method.

The present invention will be described in detail below. EVA used as a core component in the present invention preferably has an ethylene content of 35 to 70 mol% and a saponification degree of 95% or more. When the ethylene content is less than this range, the melt viscosity is increased and the melt spinnability is decreased, and when the ethylene content is more than the above range, the hydroxyl group content is decreased, so that the hydrophilicity is impaired and the composite fiber with nylon 6 is added. Has poor water absorption properties. If the degree of saponification is less than 95%, problems such as thermal decomposition during melt spinning and fusion between single yarns during drawing occur, which is not preferable. Furthermore, EV
Since A is composite melt-spun with Nylon 6, it preferably has a melting point of 150 ° C or higher and a MI (melt index) measured at 210 ° C in the range of 2 to 30.

Nylon 6 used as a sheath component has a relative viscosity (using 96% sulfuric acid as a solvent, a concentration of 1 g / dl and a temperature of 25 ° C.).
It is preferable that the measurement) is in the range of 2.0 to 4.0.

The composite ratio of the composite fibers is such that the weight ratio of core-sheath is 3 /
It is necessary to make it 7 to 7/3. When the EVA component of the core is less than this range, a composite fiber having a high heat shrinkage stress cannot be obtained. On the contrary, when the EVA component is too large, a part of the core component is exposed on the fiber surface, which causes a problem in hot water resistance. .

The composite form may be either a single-core type or a multi-core type as long as EVA is covered with nylon 6, and a concentric type is preferable in view of yarn-forming property.

The point of the present invention is that EVA is used as a core component.
The point is to use a mixture of polyethylene. The content of polyethylene must be 0.5 to 10% by weight of the core component. If it is less than this range, the effect of improving spinnability is poor, and conversely, if it is too much, spinnability decreases and high heat Fibers with shrinkage stress cannot be obtained.

Further, the conjugate fiber of the present invention simultaneously satisfies a hot water shrinkage rate of 17% or more and a heat shrinkage stress of 0.37 g / d or more. By having the shrinking properties that satisfy both of them at the same time, it is possible to obtain a fabric having a good texture and having appropriate tension, waist and resilience, and swelling after post-processing.

Next, the method for producing the conjugate fiber of the present invention will be described in detail. First, EVA is blended with polyethylene as a core component and nylon 6 as a sheath component, and the composite fiber is melt-spun and the spun yarn is taken at a take-up speed of 800 to 3500 m / min. If the take-up speed is less than 800 m / min, productivity will be poor, and the draw ratio must be increased, so peeling easily occurs at the interface between the core component and the sheath component, which causes deterioration of the strength and elongation properties of the fiber. Is not preferable. on the other hand,
If the take-up speed exceeds 3500 m / min, the draw ratio becomes too small, and it is not possible to obtain fibers having the desired high hot water shrinkage and high heat shrinkage stress.

Next, the drawn undrawn yarn is wound once or continuously drawn without winding.

The stretching must be carried out by hot stretching. In the case of ordinary polyamide fibers for clothing, since the glass transition point is near room temperature, cold stretching may be used, but EVA has a glass transition temperature of 45 to 75 ° C., so it is necessary to heat and stretch. The stretching temperature varies depending on the ethylene content of EVA used, the core-sheath ratio of the composite fiber, etc.
Stretching is performed in a stretching zone equipped with a heater having a temperature close to the crystallization temperature of VA, for example, a contact hot plate or a non-contact heat pox. At this time, before supplying to the stretching zone, EVA
It may be preheated by a heater having a temperature near the glass transition point of, for example, a heating roller.

The thermal stretching may be carried out in one stage or in multiple stages of two or more stages, and preliminary stretching for imparting pretension may be carried out prior to the thermal stretching. The draw ratio is preferably a draw ratio at which the elongation of the drawn yarn is 20 to 30%. At a low draw ratio such that the elongation of the drawn yarn exceeds 30%, not only a fiber having a sufficient hot water shrinkage ratio and heat shrinkage stress cannot be obtained, but also the elongation of the drawn yarn is too large, and it is used as a fiber for clothing. I can not use it. If the stretching ratio is too high,
Peeling easily occurs at the interface between the core component and the sheath component, which is not preferable.

[0019]

EXAMPLES Next, the present invention will be specifically described by way of examples. The measuring method of the characteristic value and the like in the present invention are as follows. (a) Strength Elongation Using Shimadzu Autograph DSS-500, sample length
It was measured at 30 cm and a pulling speed of 30 cm / min. (b) Productivity The A grade yield (%) when 100 kg of drawn yarn was produced was evaluated according to the following four grades. ◎: 80 to 100, ○: 60 to less than 80, △: 40 to less than 60,
×: Less than 40 (c) Hot water shrinkage rate A loop of 50 cm was used to obtain a length A by applying an initial load of 1/30 g / d, and then freezing and immersing in boiling water for 15 minutes, then natural After drying, a load of 1/30 g / d was applied again to obtain the length B, which was calculated by the following formula. Hot water shrinkage (%) = [(A-B) / A] x 100 (d) Heat shrinkage stress Using a KE-2 type heat shrinkage stress measuring instrument manufactured by Kanebo Engineering Co., Ltd., a sample with a length of 16 cm was looped. 8 cm,
It was measured at an initial load of 1/30 g / d and a heating rate of 100 ° C./min.
(The peak value of the heat shrinkage stress curve is the heat shrinkage stress.)

Example 1 EVA having an ethylene content of 44 mol%, a saponification degree of 98% and MI 13.0 was blended with MI 32.0 linear polyethylene as a core component, and nylon 6 having a relative viscosity of 2.60 was used as a sheath component. The concentric conjugate fiber was melt-spun according to a conventional method, cooled and solidified, and a straight type oil agent was applied thereto, and then an undrawn yarn was wound at a speed of 1200 m / min. The spinning temperature was set at 190 ° C on the core component side and 260 ° C on the sheath component side, and the spinneret temperature was set to
It was set at 250 ° C. Then, the undrawn yarn is supplied to a drawing machine and drawn so that the draw ratio DR becomes the ratio shown in Table 1 while contacting the hot plate at 140 ° C. between the first roller and the second roller at room temperature, 30d / 12f composite yarn was obtained. The results of measuring the yarn quality characteristics of the obtained composite yarn are shown in Table 1.

[0021]

[Table 1]

As is apparent from Table 1, in Examples Nos. 3, 5, and 7 to 9 of the present invention, the hot water shrinkage rate was 1 in all cases.
7% or more, the heat shrinkage stress was 0.37 g / d or more, and the productivity was good. On the other hand, in Nos. 1 and 2 in which the content of polyethylene in the core component was 0 to 0.2% by weight, yarn breakage frequently occurred in the spinning and drawing steps, resulting in poor productivity. No. 4 with a large proportion of core components (large amount of EVA)
In No. 6, a partial fusion was observed when measuring the hot water shrinkage, and the core component ratio was small (the amount of EVA was small).
Both the hot water shrinkage rate and the heat shrinkage stress were low. Also,
In No. 10 containing a large amount of polyethylene in the core component, the productivity was poor, and both the hot water shrinkage rate and the heat shrinkage stress were low.

[0023]

EFFECTS OF THE INVENTION According to the present invention, the excellent texture, dyeability, strength and elongation characteristics of nylon 6 fibers and the high heat shrinkage stress of fibers from EVA are utilized.
It is possible to industrially produce a composite fiber having a good texture and heat shrinkage property with high productivity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Murakami 5 Ujitonouchi, Uji-shi, Kyoto Prefecture Unitika stock company Uji Plant (72) Inventor Yoko Mizozo 5 Ujitonouchi, Uji-shi, Kyoto Prefecture Unitika Uji Plant Co., Ltd.

Claims (2)

[Claims] 1. A saponified ethylene / vinyl acetate copolymer containing 0.5 to 10% by weight of polyethylene as a core component and nylon 6 as a sheath component, and a core-sheath weight ratio of 7/3 to 3 is obtained.
/ 7 is a composite fiber having a hot water shrinkage rate of 17% or more,
A highly shrinkable conjugate fiber having a heat shrinkage stress of 0.37 g / d or more. 2. A high shrinkage characterized by melt-spinning a composite fiber comprising a saponified ethylene / vinyl acetate copolymer mixed with polyethylene as a core component and nylon 6 as a sheath component, and then hot drawing. Method for producing elastic composite fiber.