BICOMPONENT ELASTIC FIBER COMPOSITE MATERIAL, ELASTIC MULTIFILAMENT FIBER INCLUDING THE COMPOSITE MATERIAL, AND THE MANUFACTURING METHOD FOR THE SAME

Abstract

A bicomponent elastic fiber composite material, which has a linear density of 20-150 deniers, a stretchability of 300-600%, and a deformation rate of 0-25% after stretching to 400%. The bicomponent elastic fiber composite material includes an inner core fiber and a sheath outer layer, wherein the inner core fiber includes a polystyrne copolymer material of a styrene-butadiene block copolymer (SBS), a styrene-ethylene-butylene-styrene block copolymer (SEBS) or a thermoplastic polyolefin elastomer (TPO), or includes a thermoplastic polystyrene elastomer (TPS). The sheath outer layer includes polypropylene (PP) or polyethylene (PE). Thereby, the present invention can realize zero pollution while recycled and reused. In addition, the present invention has excellent properties of elasticity, dyeability, acid and alkali resistance, quick-drying and non-absorbency, antibacterial and deodorizing, and has a soft texture. Further, the elastic multifilament fiber including the composite material has the full effect of the bicomponent elastic fiber composite material.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of Taiwanese patent application No. 108101077, filed on Jan. 10, 2019, which is incorporated herewith by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fiber composite material, in particular, to a bicomponent elastic fiber composite material having elasticity which is formed by using a thermoplastic elastic material to constitute an inner core fiber, using a thermoplastic material to constitute a sheath outer layer, and cladding the sheath outer layer to a surface of the inner core fiber; an elastic multifilament fiber including the composite material; and a manufacturing method for the same.

2. The Prior Arts

In recent years, with the prevalence of the fashion of leisure sports, the sales volume of functional sports fabrics have also increased. Meanwhile, the demand for fabric functionality has gradually increased as well. For example, in addition to being lighter, moisture wicking, antibacterial, and deodorant, it is further desired that an elastic fiber fabric having a close-fitting comfort can reduce restraint feeling. Therefore, in material technology, there is a need for more moving possibility between stretching force and restoring force, and a need for striking an optimal balance between functionality and comfort.

Since the process steps have been improved year by year, the elastic textile fiber technology has already have advantages of easier-to-manufacturing, processing, durability, rapid production efficiency, and low cost and has been widely used in many functional sports fabrics.

However, in the conventional art, the general elastic fiber fabric still has the following disadvantages to be overcome.

First, take an elastic fiber fabric made of a diene-based elastic fiber (elastic thread) as an example, it is not suitable for a user who has severe allergic symptoms to latex. Generally, synthetic rubber such as neoprene, butyl rubber, and the like is used instead to avoid allergic reactions. However, the cost of synthetic rubber is generally higher, so that the elastic fiber fabric made of synthetic rubber is less competitive.

In addition, the materials which are more widely used to make elastic fiber fabrics also include polyurethane fiber (Spandex). However, there are several problems for polyurethane fiber: first, there are problems of difficulties in recycling; second, it produces dioxin which seriously pollutes the environment while burning; third, it has poor weather resistance and light resistance which affect the service life.

Further, polyether ester elastic fibers are also common materials for elastic fiber fabrics. However, since the fiber hardness of the polyether ester elastic fiber is higher, it affects the softness of the elastic fiber fabric. Meanwhile, since the processing conditions are also rigorous, more precise processing machines must be used and the price is considerably expensive as a result.

Moreover, each of the elastic fibers is formed by directly drawing the one-component elastomer, resulting in an inter-adhesion problem among multiple elastic fibers of the elastic fiber fabric.

In particular, the fabric has a high-temperature requirement while dyeing and setting (thermal dimensional stability, antiwrinkling). Further, for example, elastic fibers of polyurethane fibers (Spandex), polyester, and polyamide (Nylon) must withstand a high temperature of 180-240° C. with thermosetting. Moreover, the thermosetting temperature of such polyurethane elastic fibers is above 180° C., which is higher than the melting point of polypropylene (PP) fibers of 160° C. As a result, after cladding the polypropylene fibers to such polyurethane elastic fibers to form yarns, the effect of thermosetting is affected by the difference in glass transition (Tg) between different materials. It is well known that when the temperature is too low, the elastic fiber fabric cannot be wrinkle-free and stabilized in size; however, when the temperature is too high, the polypropylene fiber will convert into fluid state, lose its fiber configuration, and will be unusable as a result.

The existing polypropylene fiber is a fiber which becomes colored by adding colored masterbatch while producing the fibers. However, this will result in lower color diversity than the traditional method in which the cloth is dyed and finished after weaving.

For example, the polyester fiber has a dyeing temperature of about 130-135° C., the Nylon fiber (Nylon 66) has a dyeing temperature of about 110° C., and the OP elastic yarn has a dyeing temperature of about 125° C., which is quite high. In particular, although the OP elastic yarn (polymerized yarn) has dyeability, it is not colored, that is, the dye adheres only at the surface, so the overall dyeing fastness is extremely poor.

SUMMARY OF THE INVENTION

A primary objective of the present invention is to provide a bicomponent elastic fiber composite material, wherein the inner core fiber is constituted of a thermoplastic elastic material and the sheath outer layer is constituted of a thermoplastic material, so that the present invention has excellent elasticity.

Another objective of the present invention is to provide a bicomponent elastic fiber composite material which has excellent dyeability.

Yet another objective of the present invention is to provide a bicomponent elastic fiber composite material which has the advantages of acid and alkali resistance, quick-drying and non-absorbency, antibacterial and deodorizing, recyclable, and reusable. It has a soft texture, which is suitable for applying in thin coats, close-fitting clothing or diapers, capable of making the dressing more comfortable.

Still another objective of the present invention is to provide an elastic multifilament fiber including the composite material and the manufacturing method for the same, wherein the made elastic multifilament fiber has the full effect of the bicomponent elastic fiber composite material.

In order to achieve the objectives mentioned above, the present invention provides a bicomponent elastic fiber composite material, which is a bicomponent fiber structure with a core sheath or a core spun, comprising an inner core fiber and a sheath outer layer. The inner core fiber includes a polystyrene copolymer material of a styrene-butadiene block copolymer (SBS), a styrene-ethylene-butylene-styrene block copolymer (SEBS) or a thermoplastic polyolefin elastomer (TPO), or includes a thermoplastic polystyrene elastomer (TPS). The sheath outer layer clads to an outer surface of the inner core fiber and includes polypropylene (PP) or polyethylene (PE).

Wherein a ratio of a thickness of the sheath outer layer to a radius of the inner core fiber is between 1:9 to 9:1.

Wherein the bicomponent elastic fiber composite material has a linear density of 20-150 deniers and a stretchability of 300-600%.

Wherein the bicomponent elastic fiber composite material has a deformation rate of 0-25% after stretching to 400%.

Preferably, the inner core fiber has a stretchability of 100-600%.

Preferably, the sheath outer layer has dyeability.

Preferably, the polypropylene has a graft-dyeing base for dyeing.

Preferably, the ratio of the thickness of the sheath outer layer to the radius of the inner core fiber is 9:1, and the bicomponent elastic fiber composite material has a linear density of 30 deniers and a stretchability of 500%, and the bicomponent elastic fiber composite material has a deformation rate of 1% after stretching to 400%.

In order to achieve the objectives mentioned above, the present invention provides a manufacturing method for an elastic multifilament fiber including a composite material, which includes the following steps:

a stretching step: stretching a bicomponent elastic fiber composite material to several times;

a surrounding step: commonly surrounding a plurality of surrounding fibers to outside of the bicomponent elastic fiber composite material, and wherein an elasticity of each of the surrounding fibers is lower than that of the bicomponent elastic fiber composite material;

an air entangling step: commonly forming a plurality of air entanglement knots on the plurality of surrounding fibers and the bicomponent elastic fiber composite material to form an elastic multifilament fiber, and wherein the plurality of air entanglement knots divide the elastic multifilament fiber into a plurality of sections; and

a relaxing step: relaxing the bicomponent elastic fiber composite material such that the elastic multifilament fiber contracts back to a normal state by the deformation rate of the bicomponent elastic fiber composite material, and thus, in each section of the elastic multifilament fiber, a length of the bicomponent elastic fiber composite material is equal to a distance between adjacent two air entanglement knots, and a length of each of the surrounding fibers is greater than the distance between adjacent two air entanglement knots.

Preferably, the bicomponent elastic fiber composite material is stretched to three times in the stretching step.

Preferably, the material of each of the surrounding fibers is polyester.

In order to achieve the objectives mentioned above, the present invention provides an elastic multifilament fiber including a composite material, which includes a bicomponent elastic fiber composite material and a plurality of surrounding fibers.

Wherein the plurality of surrounding fibers commonly surround outside of the bicomponent elastic fiber composite material and commonly contact the bicomponent elastic fiber composite material by a plurality of air entanglement knots, and an elasticity of each of the surrounding fibers is lower than that of the bicomponent elastic fiber composite material.

Wherein the plurality of air entanglement knots divide the elastic multifilament fiber into a plurality of sections

Wherein in each section of the elastic multifilament fiber, a length of the bicomponent elastic fiber composite material is equal to a distance between adjacent two air entanglement knots, and a length of each of the surrounding fibers is greater than the distance between adjacent two air entanglement knots.

Preferably, the material of each of the surrounding fibers is polyester.

The effect of the present invention is that the inner core fiber is constituted of a thermoplastic elastic material and the sheath outer layer is constituted of a thermoplastic material, such that the bicomponent elastic fiber composite material and the elastic multifilament fiber including the composite material of the present invention both have excellent elasticity.

Further, the bicomponent elastic fiber composite material and the elastic multifilament fiber including the composite material of the present invention can provide excellent dyeability by the dyeable sheath outer layer.

Moreover, the bicomponent elastic fiber composite material and the elastic multifilament fiber including the composite material of the present invention can both provide the advantages of acid and alkali resistance, quick-drying and non-absorbency, antibacterial and deodorizing, recyclable, and reusable. It has a soft texture, which is suitable for applying in thin coats, close-fitting clothing or diapers, capable of making the dressing more comfortable.

In addition, the polypropylene (PP) constituting the sheath outer layer has a characteristic of low-temperature dyeing itself (a melting point about 70-110° C. lower than 160° C.), which is far lower than 130-135° C. of polyester (PET), 110° C. of nylon (Nylon 66), 125° C. of OP elastic yarn, such that the thermal energy and the dyeing time can be reduced to achieve energy-saving effect.

Furthermore, the bicomponent elastic fiber composite material of the present invention can utilize the sheath outer layer and the inner core fiber for one-time fiber drawing production, which not only has a simpler production process but also has a lower raw material cost than the commercially available elastic yarn (Spandex). Further, there is almost no pollutant generated during the production process. Moreover, it is very easy to recycle and reuse to achieve the circular economy of recycling and reuse.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating the structure of a bicomponent elastic fiber composite material of the present invention;

FIG. 2 is a cross-sectional view illustrating an elastic fiber fabric produced by feeding a plurality of bicomponent elastic fiber composite materials of the present invention into a loom in a multifilament manner;

FIG. 3 is a flow chart illustrating the manufacturing method for an elastic multifilament fiber of the present invention;

FIG. 4 is a schematic view illustrating the stretching step, surrounding step, air entangling step of the manufacturing method for the elastic multifilament fiber of the present invention; and

FIG. 5 is a schematic view illustrating the relaxing step of the manufacturing method for the elastic multifilament fiber of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the present invention will be described in more detail below with reference to the drawings and the reference numerals, such that those skilled in the art can implement it after studying this specification.

Please refer to FIG. 1 which is a schematic view illustrating the structure of a bicomponent elastic fiber composite material 1 of the present invention. The present invention provides a bicomponent elastic fiber composite material 1 comprising an inner core fiber 10 and a sheath outer layer 20. The sheath outer layer 20 clads to an outer surface of the inner core fiber 10, wherein the inner core fiber 10 is constituted of a thermoplastic elastic material and the sheath outer layer 20 is constituted of a thermoplastic material, and thus the bicomponent elastic fiber composite material 1 of the present invention has excellent elasticity. Preferably, the sheath outer layer 20 is constituted of a dyeable thermoplastic material, and thus the bicomponent elastic fiber composite material 1 of the present invention may also have dyeability.

In particular, the bicomponent elastic fiber composite material 1 of the present invention is essentially a bicomponent fiber structure with a core sheath or a core spun. In particular, the bicomponent elastic fiber composite material 1 of the present invention has a linear density of 20-150 deniers and a stretchability of 300-600%. The bicomponent elastic fiber composite material 1 of the present invention has a deformation rate of 0-25% after stretching to 400%.

Further, the inner core fiber 10 includes a polystyrene copolymer material of a styrene-butadiene block copolymer (SBS), a styrene-ethylene-butylene-styrene block copolymer (SEBS) or a thermoplastic polyolefin elastomer (TPO), or includes a thermoplastic polystyrene elastomer (TPS). Furthermore, the inner core fiber 10 has a stretchability of 100-600%.

It is well known that the thermoplastic polystyrene elastomers (TPS) mentioned above, which are also referred to as styreneic block copolymers or SBCs for short, are a type of thermoplastic elastomer with the largest production currently in the world and having the properties most similar to that of rubber. Currently, there are mainly four types in the species of SBCs series, that is: styrene-butadiene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS) and styrene-ethylene-propylene-styrene block copolymer (SEPS), wherein SEBS and SEPS are hydrogenated copolymers of SBS and SIS, respectively.

Further, the hard segment of the thermoplastic polyolefin elastomer (TPO) is a polyolefin material such as polypropylene (PP) or polyethylene (PE) or the like, wherein the soft segment thereof is a rubber such as ethylene propylene diene monomer (EPDM) and the like. Generally, it is formed by polymerization using metallocene as a catalyst, wherein the hard segment and the soft segment are directly combined by a covalent bond, so that this kind of the thermoplastic polyolefin elastomer (TPO) is also referred to as M-POE.

In addition, the sheath outer layer 20 may include polypropylene (PP) or polyethylene (PE) and has dyeability. A ratio of a thickness of the sheath outer layer 20 to a radius of the inner core fiber 10 may be between 1:9 to 9:1 for adjusting the best properties of softness, stretchability, restoring rate, tensile stress and the like according to practical needs. The polypropylene mentioned above may preferably have graft-dyeing bases for enhancing dyeability.

In a preferred embodiment, the ratio of the thickness of the sheath outer layer 20 to the radius of the inner core fiber 10 is 9:1, and the bicomponent elastic fiber composite material 1 has a linear density of 30 deniers and a stretchability of 500%, and the bicomponent elastic fiber composite material 1 has a deformation rate of 1% after stretching to 400%.

Since the polypropylene (PP) constituting the sheath outer layer 20 has a characteristic of low-temperature dyeing itself (about 70-110° C. lower than 160° C.), which is much lower than 180° C. of polyurethane fibers (Spandex), 130-135° C. of polyester (PET), 110° C. of Nylon 66, and 125° C. of the OP elastic yarn, so the thermal energy and the dyeing time can be reduced to achieve energy-saving effect.

Furthermore, the present invention can utilize the sheath outer layer 20 and the inner core fiber 10 for one-time fiber drawing production, which not only has a simpler production process but also has a lower raw material price than the commercially available elastic yarn (Spandex). Further, there is almost no pollutant generated during the production process. Moreover, it is very easy to recycle and reuse to achieve the circular economy of recycling and reuse.

In summary, the bicomponent elastic fiber composite material 1 of the present invention is characterized in that it has the advantages of acid and alkali resistance, quick-drying and non-absorbency, antibacterial and deodorizing, recyclable, and reusable. It has a soft texture, which is suitable for applying in thin coats, close-fitting clothing or diapers, capable of making the dressing more comfortable. Particularly, it has high elasticity and is easy to be dyed, and the dyeing fastness thereof is better. Furthermore, it can be mix-weaved with other fibers into functional fabrics with different high functionality, such as sports clothes or close-fitting clothing.

In addition, the bicomponent elastic fiber composite material 1 of the present invention has the characteristics of lower glass transition point, which can satisfy the dyeing and setting conditions of the polypropylene fiber while improving the problem of the fabric in boarding (for example, thermal dimensional stability), and thereby improved the situation that the yarn exchanges between face and back or the color fastness is deteriorated easily because the fibers are not capable of being dyed when the fiber is interweaved with fibers such as polyesters.

Further, fibers utilizing polypropylene having the graft-dyeing bases as the sheath outer layer 20 can have a better dyeability (SDY 110° C. dyeing) than the general polypropylene fiber, and have the same grade of washing fastness (SDY 110° C. dyeing) as polyester (PET). In particular, the practical needs of optimum properties of softness, stretchability, restoring rate, tensile stress and the like can be satisfied by adjusting the ratio of the thickness of the sheath outer layer 20 to the radius of the inner core fiber 10.

The following are explanations about further producing two types of elastic fiber fabrics by using the bicomponent elastic fiber composite material 1 of the present invention.

First, please refer to FIG. 2 which is a cross-sectional view illustrating an elastic fiber fabric 100 produced by feeding a plurality of bicomponent elastic fiber composite materials 1 of the present invention into a loom in a multifilament manner. A plurality of the bicomponent elastic fiber composite materials 1 of a preferred embodiment of the present invention are directly fed into a loom (not shown) in a multifilament manner to be woven into an elastic fiber fabric 100. Thus, the made elastic fiber fabric 100 also has the full effect of the described bicomponent elastic fiber composite material 1.

Next, please refer to FIGS. 3 to 5. FIG. 3 is a flow chart of the manufacturing method for an elastic multifilament fiber 3 of the present invention; FIG. 4 is a schematic view illustrating the stretching step, surrounding step, air entangling step of the manufacturing method for the elastic multifilament fiber 3 of the present invention; and FIG. 5 is a schematic view illustrating the relaxing step S40 of the manufacturing method for the elastic multifilament fiber 3 of the present invention. The present invention provides a manufacturing method for an elastic multifilament fiber 3, which includes a stretching step S10, a surrounding step S20, an air entangling step S30, and a relaxing step S40.

Stretching step S10: stretching a bicomponent elastic fiber composite material 1 to several times. Wherein, it is preferable to be stretched to three times.

Surrounding step S20: commonly surrounding a plurality of surrounding fibers 2 to outside of the bicomponent elastic fiber composite material 1, and wherein an elasticity of each of the surrounding fibers 2 is lower than that of the bicomponent elastic fiber composite material 1. Preferably, the material of each of the surrounding fibers 2 is polyester, which is almost inelastic.

Air entangling step S30: commonly forming a plurality of air entanglement knots P on the plurality of surrounding fibers 2 and the bicomponent elastic fiber composite material 1 to form an elastic multifilament fiber 3. The plurality of air entanglement knots P divide the elastic multifilament fiber 3 into a plurality of sections 31.

Relaxing step S40: relaxing the bicomponent elastic fiber composite material 1 such that the elastic multifilament fiber 3 contracts back to a normal state by the deformation rate of the bicomponent elastic fiber composite material 1. So that, in each section 31 of the elastic multifilament fiber 3, a length of the bicomponent elastic fiber composite material 1 is equal to a distance between adjacent two air entanglement knots P, and a length of each of the surrounding fibers 2 is greater than the distance between adjacent two air entanglement knots P. The made elastic multifilament fiber 3 has the full effect of the described bicomponent elastic fiber composite material 1.

A plurality of bicomponent elastic multifilament fibers 3 of the present invention may be further fed into a loom (not shown) to be woven into an elastic fiber fabric (not shown). Thus, the made elastic fiber fabric also has the full effect of the described bicomponent elastic fiber composite material 1.

The mentioned above are only preferred embodiments for explaining the present invention but intend to limit the present invention in any forms, so that any modifications or verification relating to the present invention made in the same spirit of the invention should still be included in the scope of the invention as intended to be claimed.

Claims

1. A bicomponent elastic fiber composite material, which is a bicomponent fiber structure with a core sheath or a core spun, comprising:

an inner core fiber including a polystyrene copolymer material of a styrene-butadiene block copolymer (SBS), a styrene-ethylene-butylene-styrene block copolymer (SEBS) or a thermoplastic polyolefin elastomer (TPO), or including a thermoplastic polystyrene elastomer (TPS); and

a sheath outer layer cladding to an outer surface of the inner core fiber, and including polypropylene (PP) or polyethylene (PE);

wherein a ratio of a thickness of the sheath outer layer to a radius of the inner core fiber is between 1:9 to 9:1;

wherein the bicomponent elastic fiber composite material has a linear density of 20-150 deniers and a stretchability of 300-600%; and

wherein the bicomponent elastic fiber composite material has a deformation rate of 0-25% after stretching to 400%.

2. The bicomponent elastic fiber composite material according to claim 1, wherein the inner core fiber has a stretchability of 100-600%.

3. The bicomponent elastic fiber composite material according to claim 1, wherein the sheath outer layer has dyeability.

4. The bicomponent elastic fiber composite material according to claim 3, wherein the polypropylene has a graft-dyeing base for dyeing.

5. The bicomponent elastic fiber composite material according to claim 1, wherein the ratio of the thickness of the sheath outer layer to the radius of the inner core fiber is 9:1, and the bicomponent elastic fiber composite material has a linear density of 30 deniers and a stretchability of 500%, and the bicomponent elastic fiber composite material has a deformation rate of 1% after stretching to 400%.

6. A manufacturing method for an elastic multifilament fiber, comprising the following steps:

a stretching step: stretching a bicomponent elastic fiber composite material to several times;

a surrounding step: commonly surrounding a plurality of surrounding fibers to outside of the bicomponent elastic fiber composite material, and wherein an elasticity of each of the surrounding fibers is lower than that of the bicomponent elastic fiber composite material;

an air entangling step: commonly forming a plurality of air entanglement knots on the plurality of surrounding fibers and the bicomponent elastic fiber composite material to form an elastic multifilament fiber, and wherein the plurality of air entanglement knots divide the elastic multifilament fiber into a plurality of sections; and

a relaxing step: relaxing the bicomponent elastic fiber composite material such that the elastic multifilament fiber contracts back to a normal state by the deformation rate of the bicomponent elastic fiber composite material, and thus, in each section of the elastic multifilament fiber, a length of the bicomponent elastic fiber composite material is equal to a distance between adjacent two air entanglement knots, and a length of each of the surrounding fibers is greater than the distance between adjacent two air entanglement knots;

wherein the bicomponent elastic fiber composite material is a bicomponent fiber structure with a core sheath or a core spun, comprises an inner core fiber and a sheath outer layer;

wherein the inner core fiber includes a polystyrene copolymer material of a styrene-butadiene block copolymer (SBS), a styrene-ethylene-butylene-styrene block copolymer (SEBS) or a thermoplastic polyolefin elastomer (TPO), or includes a thermoplastic polystyrene elastomer (TPS);

wherein the sheath outer layer clads to an outer surface of the inner core fiber, and includes polypropylene (PP) or polyethylene (PE);

wherein a ratio of a thickness of the sheath outer layer to a radius of the inner core fiber is between 1:9 to 9:1;

wherein the bicomponent elastic fiber composite material has a linear density of 20-150 deniers and a stretchability of 300-600%; and

wherein the bicomponent elastic fiber composite material has a deformation rate of 0-25% after stretching to 400%.

7. The manufacturing method according to claim 6, wherein the bicomponent elastic fiber composite material is stretched to three times in the stretching step.

8. The manufacturing method according to claim 6, wherein the material of each of the surrounding fibers is polyester.

9. The manufacturing method according to claim 6, wherein the sheath outer layer has dyeability.

10. The manufacturing method according to claim 6, wherein the polypropylene has a graft-dyeing base for dyeing.

11. The manufacturing method according to claim 6, wherein the ratio of the thickness of the sheath outer layer to the radius of the inner core fiber is 9:1, and the bicomponent elastic fiber composite material has a linear density of 30 deniers and a stretchability of 500%, and the bicomponent elastic fiber composite material has a deformation rate of 1% after stretching to 400%.

12. An elastic multifilament fiber, comprising: a bicomponent elastic fiber composite material and a plurality of surrounding fibers;

wherein the bicomponent elastic fiber composite material is a bicomponent fiber structure with a core sheath or a core spun, comprises an inner core fiber and a sheath outer layer;

wherein the inner core fiber includes a polystyrene copolymer material of a styrene-butadiene block copolymer (SBS), a styrene-ethylene-butylene-styrene block copolymer (SEBS) or a thermoplastic polyolefin elastomer (TPO), or includes a thermoplastic polystyrene elastomer (TPS);

wherein the sheath outer layer clads to an outer surface of the inner core fiber, and includes polypropylene (PP) or polyethylene (PE);

wherein a ratio of a thickness of the sheath outer layer to a radius of the inner core fiber is between 1:9 to 9:1;

wherein the bicomponent elastic fiber composite material has a linear density of 20-150 deniers and a stretchability of 300-600%;

wherein the bicomponent elastic fiber composite material has a deformation rate of 0-25% after stretching to 400%;

wherein the plurality of surrounding fibers commonly surround outside of the bicomponent elastic fiber composite material and commonly contact the bicomponent elastic fiber composite material by a plurality of air entanglement knots, and an elasticity of each of the surrounding fibers is lower than that of the bicomponent elastic fiber composite material;

wherein the plurality of air entanglement knots divide the elastic multifilament fiber into a plurality of sections; and

wherein in each section of the elastic multifilament fiber, a length of the bicomponent elastic fiber composite material is equal to a distance between adjacent two air entanglement knots, and a length of each of the surrounding fibers is greater than the distance between adjacent two air entanglement knots.

13. The elastic multifilament fiber according to claim 12, wherein the material of each of the surrounding fibers is polyester.

14. The elastic multifilament fiber according to claim 12, wherein the sheath outer layer has dyeability.

15. The elastic multifilament fiber according to claim 12, wherein the polypropylene has a graft-dyeing base for dyeing.

16. The elastic multifilament fiber according to claim 12, wherein the ratio of the thickness of the sheath outer layer to the radius of the inner core fiber is 9:1, and the bicomponent elastic fiber composite material has a linear density of 30 deniers and a stretchability of 500%, and the bicomponent elastic fiber composite material has a deformation rate of 1% after stretching to 400%.