JP2583372B2 - High shrinkage conjugate fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly shrinkable conjugate fiber having a saponified ethylene / vinyl acetate copolymer as a core component and nylon 6 as a sheath component, which is suitable for clothing and a method for producing the same.

[0002]

2. Description of the Related Art Polyamide fibers such as nylon 6 and nylon 66 have excellent texture, dyeing properties, and high elongation properties, and are widely used for clothing. I do not have.

For example, if a polyamide fiber having a high hot water shrinkage and a high heat shrinkage stress is used, it is possible to obtain a fabric having an appropriate tension, a waist, a resilience, and a swelling feeling by post-processing. Fiber has not been developed.

[0004] On the other hand, copolymers of olefins such as ethylene and propylene with vinyl acetate have excellent hydrophilicity and antistatic properties, and have a texture similar to natural fibers such as cotton and hemp. give. According to the study by the present inventors, it has been found that saponified ethylene / vinyl acetate copolymer (hereinafter abbreviated as EVA) gives fibers having high heat shrinkage stress. However, these copolymers do not have hot water resistance, and those whose components are exposed on the fiber surface do not become practically usable fibers unless subjected to hot water treatment such as acetalization.

In Japanese Patent Publication No. 54-38663, a hydrophobic thermoplastic resin such as polyamide or polyester is used as a sheath component.
There has been proposed a conjugate fiber having a texture improved by using hydrophilic olefin-modified polyvinyl alcohol as a core component and increasing the water-absorbing swelling property of the core component polymer.
Japanese Patent Publication No. 54-32874 proposes that the composite fiber is strongly twisted to obtain a woven fabric having an improved texture by utilizing a restoring stress caused by hot water swelling force. However, since these fibers use a polyvinyl alcohol-based copolymer having a low olefin content as a core component to improve hydrophilicity, melt spinning is difficult, and at the same time, when a composite fiber is used, The strength is remarkably reduced and does not have high heat shrinkage stress. Also, Japanese Patent Publication No. 56-5846
Is a composite fiber consisting of a hydrophobic thermoplastic resin and EVA
Is disclosed. However, this invention does not
To improve the antistatic properties and dyeability of fibers made of conductive resin
In the technology disclosed in this publication, high heat
Fibers with shrinkage stress are not obtained.

The present inventors have previously found that a composite fiber having EVA as a core component and polyamide as a sheath component has a high heat shrinkage property (Japanese Patent Application No. 3-115317). It has been found that it is necessary to optimize the microstructure of each component of the composite fiber in order to stably exhibit high heat shrinkage characteristics.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to an excellent feeling, dyeing property, high elongation property and the like of polyamide fiber and E
It is intended to provide a highly shrinkable conjugate fiber which has a good texture and can stably exhibit a high heat shrinkage property by utilizing the property of a high heat shrinkage stress of the VA fiber, and a method for producing the same. is there.

[0008]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and the gist is as follows. (1) A composite fiber having EVA as a core component, nylon 6 as a sheath component, and a core / sheath weight ratio of 3/7 to 7/3, which simultaneously satisfies the following characteristics: Composite fiber. (B) Δn _E ≧ 0.032 [Δn _E : birefringence of core] (b) fc _E ≧ 0.89 [fc _E : degree of crystal orientation of core] (c) fc _N ≧ 0.86 [fc _N : of sheath (D) HWS × TS ≧ 5.0 [HWS: Shrinkage ratio of boiling water (%), TS:
Heat shrinkage stress (g / d)]

Hereinafter, the present invention will be described in detail. 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. If the ethylene content is less than this range, the melt viscosity increases and the melt spinnability decreases. Conversely, if the ethylene content is too high, the hydroxyl group content decreases, so that the hydrophilicity is impaired and the composite fiber with nylon 6 is reduced. Has poor water absorption properties. On the other hand, when the saponification degree is less than 95%, there is a problem that thermal decomposition occurs at the time of melt spinning and fusion occurs between the single yarns at the time of stretching. Also, EVA
Has a melting point of
It is preferable that the MI (melt index) measured at 150 ° C. or higher and 210 ° C. is in the range of 2 to 30.

Nylon 6 used as a sheath component has a relative viscosity (concentration of 1 g / dl, 96% sulfuric acid as a solvent, temperature of 25 ° C.).
Is preferably in the range of 2.0 to 4.0.

The composite ratio of the composite fiber is such that the weight ratio of the core and the sheath is 3 /.
It is necessary to be 7 to 7/3. If the EVA component in the core is less than this range, a conjugate fiber having a high heat shrinkage stress cannot be obtained. Conversely, if 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 a single-core type or a multi-core type as long as the EVA is covered with a polyamide.

A feature of the conjugate fiber of the present invention is that the requirement (d) is satisfied, that is, the product of the boiling water shrinkage HWS (%) and the heat shrinkage stress TS (g / d) is 5.0 or more. It is in. By satisfying this condition, it is possible to obtain a fabric that has a good texture and a suitable tension by post-processing, a feeling of elasticity, resilience, and swelling.

In order to satisfy the above-mentioned heat shrinkage characteristics, it is necessary that the composite fiber satisfies the above requirements (a) to (c). First, the birefringence Δn _E of the core component EVA
Must be 0.032 or more, and in a low orientation state where Δn _E is less than 0.032, a sufficiently high heat shrinkage property is not exhibited.
Further, the crystal orientation degree fc _E of the core component EVA is 0.89 or more,
Degree of crystal orientation fc _N nylon 6 sheath component is required to be 0.86 or more. Unless the degree of crystal orientation of both is in this range, a sufficiently high heat shrinkage property is not exhibited.

Next, an example of the method for producing the conjugate fiber of the present invention will be described. First, a composite fiber having EVA as a core component and nylon 6 as a sheath component is melt-spun, cooled and solidified, and then an oil agent is applied to take it off.

In the composite fiber of the present invention, the crystal has a high arrangement,
Nylon 6 and EVA, which are components of the conjugate fiber, are hydrophilic polymers, and water is greatly involved in the growth of their crystals. Therefore, it is necessary that the oil agent used in the spinning be a straight type that does not substantially contain moisture. When a water emulsion type oil agent is used, the undrawn yarn has a large crystal size in both nylon 6 and EVA. In particular, in the crystal type of nylon 6, the ratio of α-type crystals that are stable against heat increases. That is, when an oil agent containing water is applied, the unstretched yarn already has a stable structure, which makes stretching difficult. Further, in the drawn fiber, high orientation of crystal and high orientation of molecular chains are not achieved, and it is difficult to exhibit high shrinkage characteristics. The amount of oil applied is preferably 0.4 to 1.0% by weight with respect to the fiber, but the oil applying method may be any of an oiling roller method, a guide oiling method and the like.

The take-off speed varies depending on the core-sheath ratio and the like, but is in the range of 800 to 3000 m / min. Pickup speed 800m
In order to exhibit high heat shrinkage characteristics at a rate of less than 1 / min, the stretching ratio must be increased, so that peeling is likely to occur at the interface between EVA and nylon 6, which is not preferable. On the other hand, if the take-up speed exceeds 3000 m / min, the draw ratio becomes too small, and the desired fiber having high heat shrinkage characteristics cannot be obtained, which is not preferable.

Next, the drawn undrawn yarn is drawn once or once without winding. Stretching is performed at a magnification such that the residual elongation after stretching is 20 to 30%.
This is performed by so-called hot stretching. By hot stretching, the ratio of the α-type crystal of nylon 6 is increased, the hot water resistance is improved, and fibers having high heat shrinkage characteristics are obtained. The stretching temperature varies depending on the ethylene content of the EVA used, the core-sheath ratio of the composite fiber, and the like. However, a stretcher equipped with a heater having a temperature close to the crystallization temperature of the EVA, for example, a contact hot plate or a non-contact heat box Stretched in the zone. On this occasion,
Before feeding to the stretching zone, the heater may be preheated at a temperature near the glass transition point of EVA, for example, a heating roller. The hot stretching may be performed in one stage or in two or more stages, and may be performed in advance of the thermal stretching in order to perform pre-stretching for applying pretension.

The spinning and drawing conditions are desirably selected so that the ratio α / γ of the α-type crystal and the γ-type crystal of nylon 6 is 1.6 or less for the undrawn yarn and 9.0 or more for the drawn yarn.

[0020]

Next, the present invention will be described in detail with reference to examples. In addition, the measuring method of the characteristic value in this invention is as follows. (a) High elongation Using a Shimadzu Autograph DSS-500, sample length 3
The measurement was performed at 0 cm and a tensile speed of 30 cm / min. (b) Initial Young's modulus It was determined from the initial slope of the load-elongation curve obtained at the time of measuring the elongation. (c) Boiling water shrinkage rate The yarn was formed into a loop of 50 cm, an initial load of 1/30 g / d was applied to determine the length A, then freed, immersed in boiling water for 15 minutes, air-dried, and dried again. The length B was determined by applying a load of / 30 g / d, and was calculated by the following equation. Boiling water shrinkage rate (%) = [(AB) / A] × 100 (d) Heat shrinkage stress Using a KE-2 type heat shrinkage stress measuring device manufactured by Kanebo Engineering Co., Ltd., a 16 cm long sample is looped to 8 cm. age,
The measurement was performed 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 defined as the heat shrinkage stress.) (E) Birefringence The birefringence was measured by an interference fringe method using a transmission quantitative interference microscope manufactured by Carl Zeiss Jena. (f) Degree of crystal orientation Using a RAD-RB type X-ray diffractometer manufactured by Rigaku Denki, IVA of EVA on a meridian appearing at a diffraction angle 2θ of around 70 to 85 °
20), the half-value width β (゜) of the azimuthal intensity distribution curve of each I (0140) of nylon 6 was measured and calculated by the following equation. fc = (180−β) / 180 (g) α / γ ratio A RAD-RB type X-ray diffractometer manufactured by Rigaku Corporation records a diffraction curve up to a diffraction angle 2θ = 12 to 28 °, performs waveform separation, The ratio of the integrated intensity of the α-type crystal and the γ-type crystal appearing at around 2θ = 20 to 24 ° was calculated.

Example 1 A concentric conjugate fiber having a core-sheath weight ratio of 5/5, comprising EVA having an ethylene content of 44 mol%, a saponification degree of 98% and MI 13.0 as a core component and nylon 6 having a relative viscosity of 2.60 as a sheath component. Is melt-spun according to a conventional method, and after cooling and solidifying, a straight type oil (12 parts by weight of a mineral oil-based oil containing a polyhydric alcohol ester component diluted with 88 parts by weight of a mineral oil) or a water emulsion type oil (polyvalent oil) An emulsion prepared by adding 88 parts by weight of water to 12 parts by weight of a mineral oil-based oil agent containing an alcohol ester component) was applied thereto, and the emulsion was taken up at a speed of 1000 m / min. (The oil adhesion amount and α / γ ratio of the undrawn yarn are shown in Table 1.) The spinning temperature was set at 210 ° C. for the EVA side of the core component and 260 ° C. for the nylon 6 side of the sheath component. The temperature was set at 260 ° C. Next, the undrawn yarn is supplied to a drawing machine, and 140 ° C. is applied between the first roller and the second roller.
While being in contact with the hot plate, the film was drawn so that the draw ratio DR became the ratio shown in Table 1, to obtain a 30d / 12f composite yarn. Table 2 shows the results of measuring the yarn properties of the obtained composite yarn.

[0022]

[Table 1]

[0023]

[Table 2]

In No. 1 using a straight type oil,
Nylon 6 and EVA crystals are in a high array state,
The birefringence of EVA was high, and the molecular chains were in a highly oriented state. In addition, the shrinkage property was large in both the hot water shrinkage rate and the heat shrinkage stress, and had high heat shrinkage properties. On the other hand, in No. 2 using the water emulsion type oil agent, both the crystal arrangement and the molecular chain orientation were low, and the heat shrinkage properties were inferior.

Example 2 The same core and sheath components as in Example 1 were used, and the same spinning oil as that in No. 1 of Example 1 was used. The yarn was produced in the same manner as in Example 1 at a speed and a draw ratio DR to obtain a composite yarn of 30d / 12f. Table 3 shows the results of measuring the properties of the obtained composite yarn. (N
Nos. 5 and 6 are Examples, and Nos. 3 to 4 and 7 to 8 are Comparative Examples. In the case of No. 3 consisting of EVA alone, fusion occurred, and the measurement of hot water shrinkage could not be performed.

[0026]

[Table 3]

As is evident from Table 3, Nos. 5 and 6, which are examples of the present invention, both exhibited characteristics of HWS × TS of 5.0 or more. On the other hand, No. 4 and DR with low take-off speed
In No. 7, the HWS × TS is lower than 5.0 and the nylon 6
Only the same value as that of No. 8 consisting of No. 8 was shown. In Examples 5 and 6 of the present invention, the EVA molecular chains have the crystal orientation satisfying the requirements (B) and (C), and the EVA molecular chains have the high orientation state satisfying the requirement (A). And a high heat shrink property is exhibited by these molecular structures. On the other hand, Nos. 4 and 7 having low heat shrinkage characteristics
Then, the requirements of (b), (c) and (a) are not satisfied.

[0028]

According to the present invention, the excellent texture, dyeing properties, high elongation and the like of nylon 6 fiber and the high heat shrinkage property of EVA fiber are utilized, and the nylon 6 fiber has a good texture and is stable. Thus, a highly shrinkable conjugate fiber that can exhibit high heat shrinkage characteristics is provided.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kazuya Nagatomi 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Central Research Institute Co., Ltd. (56) References JP-B-54-38663 (JP, B2)

Claims (1)

(57) [Claims] 1. A saponified ethylene / vinyl acetate copolymer having a core component and nylon 6 having a sheath component.
A highly shrinkable conjugate fiber which is 7 to 7/3, and simultaneously satisfies the following characteristics. (B) Δn _E ≧ 0.032 [Δn _E : birefringence of core] (b) fc _E ≧ 0.89 [fc _E : degree of crystal orientation of core] (c) fc _N ≧ 0.86 [fc _N : of sheath (D) HWS × TS ≧ 5.0 [HWS: Shrinkage ratio of boiling water (%), TS:
Heat shrinkage stress (g / d)]