JP2549773B2 - Composite fiber and its manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite fiber containing a saponified ethylene / vinyl acetate copolymer as a core component and a polyamide 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, by using a polyamide fiber having a high shrinkage ratio of hot water and a high heat shrinkage stress, it is possible to obtain a fabric having appropriate tension, waist, resilience, and bulge by post-processing. No polyamide fiber has been developed. That is, a polyamide fiber having a high hot water shrinkage can be obtained by appropriately selecting a drawing condition, but a polyamide fiber having a high heat shrinkage stress is presumed to be related to a hydrogen bond peculiar to a polymer, You can't get it just by controlling.

[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. Further, according to the studies made by the present inventors, it has been found that a saponified ethylene / vinyl acetate copolymer having a high ethylene content (hereinafter abbreviated as EVA) gives a fiber having a 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.

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 having an improved texture by strongly twisting the composite fiber and utilizing the restoring stress due to 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. Also, Japanese Patent Publication No. 56-5846
Is a composite fiber consisting of a hydrophobic thermoplastic resin and EVA
Is disclosed. However, this invention is
To improve the antistatic properties and dyeability of fibers made of conductive resin
However, in the technology disclosed in this publication, high heat
Fibers with shrinkage stress are not obtained.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to the excellent texture, dyeability, and strength / elongation characteristics of polyamide fiber and E
The present invention intends to provide a conjugate fiber having a good texture and heat shrinkage property, and a method for producing the same, by taking advantage of the high heat shrinkage stress property of the fiber from VA.

[0007]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and the gist is as follows. (1) With ethylene content of 35 to 70 mol% and EVA having a saponification degree of 95% or more as a core component and polyamide as a sheath component, the core-sheath weight ratio is 7/3 to 3/7 and the hot water shrinkage ratio is A composite fiber characterized by having a heat shrinkage stress of not less than 15% and not less than 0.32 g / d.

(2) Ethylene content 35-70 mol
%, A saponification degree of 95% or more, when producing a composite fiber having EVA as a core component and polyamide as a sheath component, the melt spun yarn is drawn at a take-up speed V of 800 to 3500 m / min, and 120 ° C. or more, A draw ratio DR satisfying the following formula in a draw zone in a temperature range lower than the melting point of the core component by 15 ° C. or more.
A method for producing a composite fiber, which comprises stretching the composite fiber. 1.0 + 1250 / V ≦ DR ≦ 2.5 + 1250 / V

The present invention will be described in detail below. The EVA used as the core component in the present invention must have 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, the melt spinnability is decreased, and conversely, when the ethylene content is large, the amount of hydroxyl groups is decreased, the hydrophilicity is impaired, and the composite fiber with polyamide is , The water absorption property is inferior. 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. further,
EVA is compound melt-spun with polyamide,
It is preferable that the MI (melt index) measured at a melting point of 150 ° C or higher and a viscosity of 210 ° C is in the range of 2 to 30.

The polyamide used as the sheath component may be any one that can be melt-spun, such as nylon 6,
Examples thereof include nylon 66, polymethaxylylene adipamide, and copolymers and blends containing these as the main components.
Above all, nylon 6 has a melting point close to that of EVA.
Is preferred. Polyamide has a relative viscosity of 2.0- (measured at a concentration of 1 g / dl and a temperature of 25 ° C. using 96% sulfuric acid as a solvent).
The range of 4.0 is preferable.

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. 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 either a single-core type or a multi-core type as long as EVA is covered with polyamide, and a concentric type is preferable in consideration of the spinnability.

The feature of the conjugate fiber in the present invention is that it simultaneously satisfies a hot water shrinkage ratio of 15% or more and a heat shrinkage stress of 0.32 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. If either one of the hot water shrinkage rate and the heat shrinkage stress falls below the above range, a desired fabric having a good texture cannot be obtained.

Next, the method for producing the conjugate fiber of the present invention will be described in detail. First, a composite fiber having EVA as a core component and polyamide as a sheath component is melt-spun and a spun yarn is spun at 800 to 3500 m.
Pick up at a pick-up speed of / min. When the take-up speed is less than 800 m / min, the productivity is poor, and the draw ratio must be increased, so that peeling easily occurs at the interface between EVA and polyamide, which causes deterioration of the strength / elongation property of the fiber. 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 ratio and high heat shrinkage stress.

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

The stretching must be carried out by so-called 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,
Since EVA has a glass transition temperature of 45 to 75 ° C., it is necessary to heat and stretch it. Stretching temperature is EVA used
Although it depends on the ethylene content, the core-sheath ratio of the composite fiber, etc., it is drawn in a drawing zone equipped with a heater having a temperature close to the crystallization temperature of EVA, for example, a contact hot plate or a non-contact heat pox. At this time, it is desirable to preheat with a heater having a temperature near the glass transition point of EVA, for example, a heating roller, before being supplied to the stretching zone.

At this time, the draw ratio must be within the range that satisfies the above formula. If the draw ratio is too low, fibers having sufficient hot water shrinkage and heat shrinkage stress cannot be obtained, and the residual elongation is too large to be used as clothing fibers. Further, if the stretching ratio is too high, peeling easily occurs at the interface between EVA and polyamide, which is not preferable.

The hot 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.

[0019]

EXAMPLES Next, the present invention will be specifically described by way of 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) Hot water shrinkage A loop of 50 cm was used for the yarn, an initial load of 1/30 g / d was applied to obtain the length A, which was then freed and immersed in boiling water for 15 minutes, then naturally dried and again. The length B was obtained by applying a load of 1/30 g / d, and 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 16 cm long sample was formed into a loop. The measurement was performed at an initial load of 1/30 g / d and a temperature rising rate of 100 ° C./min. (The peak value of the heat shrinkage stress curve is the heat shrinkage stress.)

Example 1 A concentric conjugate fiber having an ethylene content of 44 mol%, a saponification degree of 98%, an MI 13.0 EVA as a core component, and a nylon 6 having a relative viscosity of 2.60 as a sheath component was melt-spun according to a conventional method, Cooling air was blown from the lateral direction to cool the undrawn yarn at various take-up speeds V shown in Table 1, and the undrawn yarn was wound up.

The spinning temperature was 21 on the EVA side of the core component.
At 0 ° C, the nylon 6 side of the sheath component was set to 260 ° C, and the spinneret temperature was set to 260 ° C.

Next, the undrawn yarn is fed to a drawing machine and predrawn to 1.013 times between the first roller at room temperature and the second roller at 50 ° C., and then the second roller and the third roller at room temperature are combined. In between
While being brought into contact with a hot plate of 140 ° C., drawing was performed so that the draw ratio DR was the ratio shown in Table 1 to obtain a 70d / 24f composite yarn.

The results of measuring the yarn quality characteristics of the obtained composite yarn are shown in Table 1.

[0024]

[Table 1]

It should be noted that in No. 1 consisting of EVA alone, fusion occurred and the hot water shrinkage ratio could not be measured, and in No. 2 containing a large amount of EVA, similar partial fusion was observed. . Also,
In No. 3 having a slow take-up speed, the stretching ratio was large, and therefore, when the cross-sectional shape was observed, peeling was partially observed at the interface between both components.

As is clear from Table 1, in Examples Nos. 4, 5 and 6 of the present invention, the hot water shrinkage is 15%.
As described above, the characteristic is that the heat shrinkage stress is 0.32 g / d or more. On the other hand, in Nos. 2 and 9 in which the core component or the sheath component is out of the range of the present invention, the heat shrinkage stress is lower than 0.32 g / d,
It showed a value similar to that of No. 10 fiber consisting of nylon 6 only. Further, the draw ratio is lower than the range of the present invention.
In No. 7 and No. 8 in which the take-up speed is larger than the range of the present invention, both the hot water shrinkage rate and the heat shrinkage stress are 15 respectively.
%, Lower than 0.32 g / d.

Example 2 Unstretched yarn obtained by melt spinning in the same manner as in Example 1 at a core-sheath weight ratio of 5/5 and a take-up speed of 1200 m / min was fed to a stretching machine, and a first roller at room temperature was used. 1.01 with the second roller at 50 ℃
After being pre-stretched to 3 times, while being brought into contact with the hot plate of each temperature shown in Table 2 between the second roller and the third roller at room temperature, the stretching ratio was 3.24 times, and 70d / 24f A composite yarn was obtained.

The results of measuring the yarn quality characteristics of the obtained composite yarn are shown in Table 2.

[0029]

[Table 2]

In Nos. 11 and 12 which are the examples of the present invention, the hot water shrinkage is 15% or more and the heat shrinkage stress is 0.32 g / d.
The above characteristics are shown. On the other hand, in No. 13 in which the temperature of the hot plate is lower than 120 ° C, winding due to single yarn breakage occurs frequently on the third roller, and the temperature of the hot plate is higher than the melting point of EVA No. 14
Then, the drawability was poor such that a part of the yarn was fused and the yarn after drawing was cured.

Example 3 A core-sheath weight ratio was set to 5/5, and a yarn spun at a take-up speed of 1200 m / min in the same manner as in Example 1 was continuously wound without being once wound, and then taken up with a take-up roller and 50 ° C. Pre-stretched 1.013 times between the two rollers, and then stretched between the second roller and the third roller at 140 ° C through a non-contact type heat box at 140 ° C so that the stretching ratio becomes 3.0 times. Then, a 70d / 24f composite yarn was obtained.

There is no problem in spinning and drawability, and the yarn quality characteristics of the obtained composite yarn are strength 6.51 g / d, elongation 21.1%, initial Young's modulus 65.2 g / d, hot water shrinkage 17.9%, heat Shrinkage stress 0.42
It was g / d.

[0033]

EFFECTS OF THE INVENTION According to the present invention, the excellent texture, dyeing property, strength and elongation property of polyamide fiber and the high heat shrinkage stress of fiber from EVA are utilized.
A composite fiber is provided that has good hand and heat shrink properties.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunichi Kiriyama, 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Central Research Laboratories (72) Inventor Shigemitsu Murase, 23, Uji Kozakura Uji City, Kyoto Prefecture Unitika Central Research Institute ( 72) Inventor Masatsugu Mochizuki 23, Uji Kozakura, Uji City, Kyoto Prefecture Unitika Central Research Institute (56) References Japanese Patent Publication No. 54-38663 (JP, B2)

Claims (2)

(57) [Claims] 1. An ethylene content of 35 to 70 mol%, a saponification degree
95% or more of saponified ethylene / vinyl acetate copolymer is the core component and polyamide is the sheath component, and the core-sheath weight ratio is 7 / 3-
3/7, hot water shrinkage of 15% or more, heat shrinkage stress of 0.
A composite fiber characterized by being 32 g / d or more. 2. Ethylene content 35-70 mol%, Ken
When a saponified ethylene / vinyl acetate copolymer having a degree of chemical conversion of 95% or more is used as a core component and a polyamide is used as a sheath component, a melt-spun yarn is produced at 800 to 3500 m /
A method for producing a conjugate fiber, which is drawn at a drawing speed V of minutes and drawn at a draw ratio DR satisfying the following formula in a drawing zone in a temperature range of 120 ° C. or higher and a temperature of 15 ° C. or higher lower than the melting point of the core component. 1.0 + 1250 / V ≦ DR ≦ 2.5 + 1250 / V