JP2000234218A - Polyamide conjugated fiber having excellent heat retaining property and feeling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject fiber capable of preparing a fabric not easily collapsed and exhausted, having lightness, heat retaining property and slight twisting the same as cotton surface and excellent in feeling by limiting area ratios of the sheath, the hollow part and the insular part of fiber section within specified ranges. SOLUTION: This fiber is a sheath-core fiber consisting of polyamide such as nylon 6 and the core comprises a hollow part 2 and an insular part 3 wherein the area ratio of the sheath 1 is 5-55% based on the fiber sectional area, the area ratio of the hollow part 2 is >=20% and the area ratio of the insular part 3 is >=10%. The sheath is an readily alkali-soluble thermoplastic resin including 5-80 wt.% polyamide such as (5-sodium sulfoisophthalic acid-coplymerized) polyethylene terephthalate and the sheath 1 is obtained by alkali reduction of the sheath-core conjugated fiber consisting of a polyamide resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conjugate fiber having a hollow portion made of polyamide, which can be knitted and woven to obtain a lightweight, heat-insulating cloth having an excellent texture. It relates to a conjugate fiber.

[0002]

2. Description of the Related Art In order to impart lightness and heat retention to a fabric made of polyamide fiber, the form of the polyamide fiber is made hollow, a high degree of irregularity is provided to provide a space between the fibers, and There is a method of forming hollow fibers having a high degree of irregularity. However, such a fiber has a problem in that the fiber formability is poor, and the hollow portion is cracked and the fiber shape is deformed in the processing up to fabric.

[0003] In order to solve this problem, there has been proposed a fiber which is formed into a conjugate fiber having no hollow portion in the spinning step, formed into a fabric, and then the hollow portion is formed by reducing the amount of alkali. For example, JP-A-3-124857,
JP-A-3-249266, JP-A-4-245985, the hollow fiber obtained by reducing the alkali-weight of the core-sheath conjugate fiber with polyamide sheath, polyester core, and the core and sheath. Fibers with spaces between them have been proposed.

[0004] These fibers have improved yarn-making properties,
In the case of hollow fibers, crushing occurs when the ratio of the sheath is small,
Further, since the strength was low, the fabric obtained from this fiber had sagging and was inferior in heat retention. On the other hand, even for fibers having a space between the core and the sheath, the entire core is made of polyester, so that the resulting fabric has a problem in that it is excellent in abrasion and stiffness but poor in flexibility. In addition, since a part of the polyester in the core is subjected to weight reduction processing to form a space, the speed of weight reduction processing is slow, and there is also a problem in cost.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, has a high hollow ratio, is hard to be crushed even if the ratio of the sheath portion is small, and has no sagging when knitting and weaving. The technical object of the present invention is to provide a polyamide conjugate fiber which is rich in the fiber and has a light twist similar to that of the cotton surface on the fiber surface, and is capable of obtaining a cloth having a cotton-like and excellent texture. It is.

[0006]

Means for Solving the Problems The present inventors have studied to solve such problems, and as a result, have reached the present invention. That is, the present invention relates to a core-sheath composite fiber made of polyamide, in which the core portion is composed of a hollow portion and an island portion, and the area ratio of the sheath portion in the fiber cross section is 5 to 55%, and the area ratio of the hollow portion is 5%. The gist of the present invention is a polyamide composite fiber having a heat retaining property and an excellent texture, characterized in that the proportion of the island-shaped portion is at least 20% and the proportion of the island-shaped portion is at least 10%.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The polyamide conjugate fiber of the present invention is a core-sheath conjugate fiber, in which the core portion is composed of a hollow portion and an island portion, and the sheath portion and the island portion are composed of polyamide. The polyamide in the present invention is an amide bond (-CONH-) formed from an aminocarboxylic acid, a lactam or a diamine and a dicarboxylic acid.
Is a polymer or a copolymer having The following are examples of monomers for forming such a polyamide.

Examples of the aminocarboxylic acid include 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and the like. Examples of the lactam include ε-caprolactam and ω-laurolactam. As the diamine, tetramethylene diamine, hexamethylene diamine, undecamethylene diamine, dodecamethylene diamine, 2,2,2-trimethylhexamethylene diamine, 2,
Examples thereof include 4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, 2,4-dimethyloctamethylenediamine, and metaxylenediamine.

The dicarboxylic acids include adipic acid, sebacic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, Hydroterephthalic acid, hexahydroisophthalic acid, diglycolic acid and the like can be mentioned.

[0010] Specifically, nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 116
, Nylon 11, Nylon 12, Nylon MXD6, etc. are preferred, and Nylon 6 is particularly preferred in view of cost and spinnability.

These polyamides have other copolymer components, an antistatic agent, a plasticizer, a pigment, a colorant, a flame retardant, a reinforcing agent, a lubricant, and the like, to the extent that the original properties are not impaired.
An antistatic agent, an antioxidant, an ultraviolet absorber, a light stabilizer and the like may be added.

The degree of polymerization of the polyamide may be within the range used for general clothing, and in the case of nylon 6, the relative viscosity is preferably 2.0 to 3.5. It is not preferable that the relative viscosity is larger or smaller than this range because the spinnability rapidly decreases.

It is preferable that the polyamide constituting the sheath and the core island is of the same type, but they may be of different types.

Next, the shape of the polyamide composite fiber of the present invention will be described with reference to the drawings. 1 (A) to 1 (D) are schematic cross-sectional views showing the cross-sectional shape of the polyamide composite fiber of the present invention. In the polyamide composite fiber of the present invention, the area ratio of the sheath 1 in the fiber cross section is 5 to 55%, preferably 10 to 45%.
%, The area ratio of the hollow portion 2 is 20% or more, and the island-shaped portion 3
Is 10% or more.

The polyamide conjugate fiber of the present invention has such a structure, and since both the core and the island-like portion are made of polyamide, even if the ratio of the sheath portion is small and the ratio of the hollow portion is high, The strength is maintained by the island-like portions, the fibers are not crushed, and the heat retention is excellent. Then, when weaving and weaving, a light twist similar to the cotton surface is generated on the fiber surface, and a cotton-like fabric having excellent texture is obtained.

When the ratio of the sheath portion is less than 5%, the sheath portion becomes too thin, the sheath portion is easily broken, and the fiber surface is easily fibrillated. On the other hand, if it exceeds 55%, the sheath becomes thick, and the same light twisting as on the cotton surface as described above does not occur, resulting in poor texture. In addition, when the island-shaped portion of the core is substantially connected to the sheath,
The sheath portion also includes this island-shaped portion.

Next, if the area ratio of the hollow portion is less than 20%, the obtained fabric is inferior in heat retention, and if the ratio of the island portion is less than 10%, the fiber strength cannot be maintained. Then, the fabric is crushed, and the resulting fabric has sagging.

The core may have a single island (FIGS. 1C and 1D) or a plurality of islands (FIGS. 1A and 1B). The existing position may be any position. And the shape of the sheath and the core in the fiber cross section is
In addition to a circular cross section, a deformed shape such as a flat, six-lobe, or triangular cross section may be used. Above all, a circular cross section is preferable because it is easy to twist like a cotton surface.

The polyamide conjugate fiber of the present invention may be produced by melt-spinning directly from a spinneret in order to obtain the above-described core-sheath structure. In order to produce the core with good operability without causing the alkali, the core is made of an alkali-soluble thermoplastic resin containing 5 to 80% by weight of a polyamide. It is preferable to elute the thermoplastic resin to obtain the polyamide composite fiber of the present invention.

In this case, the alkali-soluble thermoplastic resin containing polyamide used for the core of the core-sheath composite fiber is not particularly limited as long as it can be melt-spinned by blending with polyamide and can reduce the alkali. ,
A polymer or a copolymer having an ester bond (—COO—) is preferred. Examples of the polymer or copolymer having an ester bond include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Among them, polyethylene terephthalate is preferred in terms of cost.

The copolymer component of the copolymer having an ester bond includes isophthalic acid, phthalic anhydride, 5-sodium sulfoisophthalic acid, naphthalenedicarboxylic acid, diethylene glycol, propylene glycol,
, 4-cyclohexanedimethanol, pentaerythritol, 4-hydroxybenzoic acid, ε-caprolactam, adipic acid, sebacic acid, 1,4-butanediol, 1,6-
Hexanediol, polyethylene glycol and the like can be mentioned. These copolymerization components may be added as needed, and among them, 5-sodium sulfoisophthalic acid and polyethylene glycol are particularly preferable because addition thereof facilitates alkali reduction.

When polyethylene terephthalate is used as the alkali-soluble thermoplastic resin, the polyethylene terephthalate preferably has a relative viscosity of 1.0 to 1.6. If the relative viscosity is larger than this range, spinning stress is high and it is difficult to control oriented crystallization. On the other hand, if the relative viscosity is smaller than this range, the viscosity difference from polyamide becomes too large, which is not preferable.

In addition, the alkali-soluble thermoplastic resin also includes
Like the polyamide resin, other copolymer components and various additives may be added to the extent that the original properties are not impaired. If titanium oxide is contained as a matting agent, etc., when the alkali is reduced, the titanium oxide tends to adhere to the inner wall of the hollow portion and cause spots of gloss. It is preferable that both of the plastic resins do not substantially contain titanium oxide.

It is preferable that the alkali-soluble thermoplastic resin contains polyamide in an amount of 5 to 80% by weight. That is, since the polyamide forms an island portion after the alkali weight reduction treatment, if the amount of the polyamide is more than 80% by weight, it becomes difficult to make the hollow portion in the fiber cross section 20% or more, while 5% by weight. If it is less than 10%, it is difficult to make the island-shaped portion in the fiber cross section 10% or more.

As a method for uniformly dispersing the polyamide in the alkali-soluble thermoplastic resin, it is preferable to knead the polyamide during spinning. For example, it is preferable to use a kneading method using a static mixer in a line in an extruder or to prepare a master chip of a polyamide and an alkali-soluble thermoplastic resin.

The fiber shown in FIG. 1 is obtained by performing the alkali reduction treatment as described above.
(A) is an example in which a plurality of island-shaped portions (polyamide) are irregular and present, (B) is an example in which the island-shaped portions are aggregated to some extent and a part of them is attached to the sheath, (C), ( D) is (A) or (B)
This is an example in which aggregation of a plurality of islands further progresses to form one island.

Next, a method for producing the polyamide composite fiber of the present invention will be described. When spinning and manufacturing the polyamide composite fiber of the present invention having a hollow portion formed from the beginning,
When producing a core-in-sheath composite fiber in which a core portion contains an alkali-soluble thermoplastic resin and a hollow portion is formed by alkali reduction treatment, melt spinning is performed using a known composite spinning apparatus.

The melt-spun yarn is cooled to a temperature lower than the glass transition temperature, and a drawn yarn is obtained at a speed of 400 to 5000 m / min. The presence or absence and the temperature and length of the heating cylinder, the temperature of the cooling air, the blowing amount, the take-up speed, the discharge amount, and the number of holes in the base are appropriately adjusted.

The obtained yarn is stretched, and the stretching may be performed by any of a two-step method in which the yarn is once wound and then stretched, and a direct spinning and stretching method in which the yarn is continuously stretched without winding. . In addition, any of cold stretching and hot stretching may be used. Examples of the heating device in the thermal stretching include a hot roll, a heat plate, a steam jet device, and the like, and these may be appropriately used in combination. The drawn yarn is subjected to a heat treatment or a relaxation treatment as necessary.

In the case of the conjugate fiber containing the alkali-soluble thermoplastic resin in the core portion, in order to obtain the polyamide conjugate fiber of the present invention, the alkali-soluble thermoplastic resin is subjected to alkali weight reduction treatment and eluted and removed at the stage of forming the fabric. It is preferable, but the method of weight reduction is not particularly limited, and caustic alkali (concentration: 10 to 100 g / l, temperature: about 80 to 120 ° C.), for example, caustic soda or caustic potash is used.
The treatment conditions are appropriately adjusted depending on the thickness of the sheath, the kind of polyamide or the alkali-soluble thermoplastic resin, the degree of oriented crystallization of the fiber, and the like.

[0031]

Next, the present invention will be described specifically with reference to examples. The measurement of the characteristic values is as follows. (a) Relative viscosity of polyamide A solution having a concentration of 1.0 g / dl was measured at a temperature of 25 ° C. using 96% sulfuric acid as a solvent. (b) Relative viscosity of polyester The measurement was carried out at a concentration of 0.5 g / dl and a temperature of 20 ° C. using an equal weight mixture of phenol and tetrachloroethane as a solvent. (c) Strong elongation Measured according to the method described in JIS L-1013 7.5.1. (d) Alkali weight loss rate (%) It was calculated by the following equation. [(Weight before weight loss-weight after weight loss) / weight before weight loss] x
100 (e) Fiber surface shape (presence or absence of twist and sheath breakage) The fiber surface was observed with an electron microscope at a magnification of 3000 times, and light twist similar to the cotton surface and the presence or absence of sheath breakage in the sheath portion were examined. (f) Ratio of sheath portion, hollow portion and island portion After the fiber cross section was photographed with an optical microscope or an electron microscope, the area of each was measured from the photograph, and the ratio to the total cross sectional area was determined. (g) The basis weight of the fabric The fabric after the alkali weight reduction treatment was converted into a 25 cm x 25 cm test piece,
Dry enough to be below the equilibrium moisture content, 20 ℃, 65% RH
After being left in the room for 24 hours to achieve water equilibrium, the weight of the test piece was measured, the weight of the obtained test piece was converted to per 1 m ^2, and the average value of five cloths was used as the basis weight. . (h) Texture of Fabric The fabric after the alkali weight loss treatment was judged to have a cotton-like texture and flexibility by touch. Those excellent in both of these properties were evaluated as good, and those inferior were evaluated as bad. (i) Insulation (CLO value) Using a fabric after the alkali weight reduction treatment, humidify the environment in an environment of 20 ° C and 65% RH, and place it on a Sm ² hot plate set at 40 ° C ± 0.1 ° C. The heat loss amount released from the hot plate to the environment through the fabric in a stable state after a lapse of one minute from the hot plate is calculated from the hot plate area Sm ² and the power consumption EW by the following formula.
At this time, in order to prevent heat radiation due to convection from the hot plate, the surroundings of the hot plate were covered with a resin case having an opening / closing opening at an upper portion to prevent a wind. CLO value = (1 / 0.155) x (20 x S / E)

Example 1 Nylon 6 having a relative viscosity of 2.5 (manufactured by Unitika, hereinafter abbreviated as N6), 2.0 mol% of 5-sodium sulfoisophthalic acid,
Using polyethylene terephthalate (manufactured by Unitika, hereinafter abbreviated as AS; alkali-soluble thermoplastic resin) obtained by copolymerizing 12.0 mol% of polyethylene glycol, N6 is used for the sheath portion and AS is used for the core portion using an ordinary composite melt spinning apparatus. 30% by weight of N6
The mixed resin contained therein was arranged, and melt-spun at 285 ° C. using a spinneret having 24 circular holes having a hole diameter of 0.35 mm so that the ratio of the sheath was 16% by weight. Then, the yarn spun from the die is passed through a heating cylinder (5 cm) heated to 300 ° C., and solidified by blowing cooling air (speed: 0.8 m / sec) at a temperature of 18 ° C. This was wound up at a speed of 4300 m / min to obtain a highly oriented undrawn yarn. The obtained undrawn yarn was drawn so as to have a draw ratio of 1.297, and was drawn at a speed of 680 m / min to obtain a fiber of 70 denier / 24 filaments. Table 1 shows the results of measuring the strength and elongation of the obtained fibers.
Shown in Next, the obtained fiber was knitted in a tube, scoured with 2 g / l of actinol, and then mixed with 40 g / l of caustic soda for 30 minutes, 100
An alkali weight reduction treatment was performed at ℃ to obtain a fabric comprising the polyamide composite fiber of the present invention.

Examples 2 to 7 and Comparative Examples 1 to 4 The same as Example 1 except that the ratio of the sheath during melt spinning and the ratio of N6 in the polymer of the core were changed as shown in Table 1. I went to.

Examples 8 to 9 Instead of the core AS, polyethylene terephthalate (hereinafter abbreviated as PET) having a relative viscosity of 1.38 (Example 8), polypropylene terephthalate (hereinafter abbreviated as PPT) (Example 9)
Was performed in the same manner as in Example 1 except that was used.

In Examples 1 to 9 and Comparative Examples 1 to 4, the alkali weight loss rate, the basis weight, texture, and heat retention of the fabric after the alkali weight loss treatment, and the fiber surface shape of the fiber taken out from the fabric after the alkali weight loss treatment Table 1 shows the results of measuring (evaluating the presence or absence of twisting and tearing of the sheath), the ratio of the sheath portion, the island-shaped portion, and the hollow portion and evaluating them.

[0036]

[Table 1]

As is clear from Table 1, in Examples 1 to 9, since the core was made of nylon and an alkali-soluble polyester, when the alkali was reduced, the weight could be reduced quickly. And the fiber after weight loss has no sheath crack on the surface,
Twist was observed, light weight, good texture, good CLO value, and excellent heat retention. On the other hand, Comparative Example 1
In the above, since the core portion was all polyester obtained by copolymerizing 5-sodium sulfoisophthalic acid and polyethylene glycol, the rate of weight loss was slow, and the fiber after the weight loss treatment had too little island-shaped portion, Since the fabric was torn, the obtained fabric was inferior in texture. Since the fiber of Comparative Example 2 had too little hollow portion, no twist was observed on the fiber surface, and the obtained fabric was inferior in both heat retention and texture. In Comparative Example 3, since the ratio of the sheath portion was too small, the sheath was broken, and the obtained fabric had poor texture. Since the fiber of Comparative Example 4 had too much sheath portion, no twist was observed on the fiber surface, and the obtained fabric was inferior in texture.

[0038]

The fiber of the present invention has a high hollow ratio, is hard to be crushed even if the ratio of the sheath portion is small, has no sagging, is lightweight, has excellent heat retention, and is as light as the cotton surface. Since it has a twist, it is possible to obtain a fabric excellent in texture such as heat retention and flexibility by knitting and weaving.

[Brief description of the drawings]

FIGS. 1A to 1D are schematic cross-sectional views showing an embodiment of a polyamide conjugate fiber of the present invention.

[Explanation of symbols]

 1 sheath part 2 hollow part 3 island part

Continued on the front page (72) Inventor Kazuaki Taruishi 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika F. term in Central Research Laboratory 4L031 AA20 AB06 AB10 BA11 CA01 DA00 DA01 4L041 AA08 AA18 AA20 BA04 BA05 BA16 BA17 BA24 BA42 BC04 BC20 BD14 CA06 CA08 CA16 CA21 DD01 DD11 DD14 DD18 EE08 EE15 EE20 4L045 AA05 BA03 BA18 BA20 BA24 BA49 BA51 BA60 CA25 CB09 CB13 DA15 DA23 DA42 DA48 DC03

Claims (2)

[Claims] 1. A core-sheath conjugate fiber comprising a polyamide, wherein a core portion comprises a hollow portion and an island-like portion, and the area ratio of the sheath portion in the fiber cross section is 5 to 55%, and the area ratio of the hollow portion is 2%.
A polyamide composite fiber having heat retention and excellent texture, characterized in that the area ratio of the island-shaped portion is 0% or more and 0% or more. 2. The core according to claim 1, wherein the core is obtained by subjecting a core-sheath conjugate fiber made of a polyamide resin to alkali reduction treatment, and the sheath is obtained by subjecting the core-sheath composite fiber made of a polyamide resin to 5-80% by weight of polyamide. Polyamide conjugate fiber with heat retention and excellent texture.