Crimped composite fiber, and fibrous mass and testile product using the same

Abstract

A crimped conjugate fiber of the present invention is a conjugate fiber containing a first component and a second component, the first component containing polybutene-1 and linear low density polyethylene, the linear low density polyethylene content being 2 to 25 mass %, the second component 2 containing a polymer having a melting peak temperature at least 20° C. higher than the melting peak temperature of polybutene-1 or a polymer having a melting initiation temperature of 120° C. or higher, when viewed from a fiber cross-section, the first component occupies at least 20% of the surface of the conjugate fiber 10 and the centroid position of the second component not overlapping the centroid position of the conjugate fiber, the conjugate fiber is an actualized crimping conjugate fiber in which three-dimensional crimps have been developed or a latently crimpable conjugate fiber in which three-dimensional crimps are developed by heating. Accordingly, a crimped conjugate fiber having high elasticity, a high level of bulk recovery properties, and high durability against repetitive compression as well as high elasticity, a high level of bulk recovery properties, and high durability when used at high temperatures, and a fiber assembly that uses the crimped conjugate fiber are provided.

Description

TECHNICAL FIELD[0001]The present invention mainly relates to an actualized crimping conjugate fiber and a latently crimpable conjugate fiber suitable for a fiber assembly having high elasticity and a high level of bulk recovery properties, in particular a nonwoven fabric, and to a fiber assembly and a fiber product that use such a conjugate fiber.BACKGROUND ART[0002]Thermally bonded nonwoven fabrics containing a thermally fused conjugate fiber composed of a low-melting-point component that is exposed at least partially on the surface of the fiber and a high-melting-point component that has a melting point higher than that of the low-melting-point component are used in various applications, such as nonwoven fabrics used for hygienic materials, packaging materials, wet tissue, filters, wipers, and the like, nonwoven fabrics used for hard stuffing, chairs, and the like, and molded articles. In particular, as a urethane foam substitute, there is a growing demand for a nonwoven fabric ...

AI Technical Summary

Benefits of technology

[0019]In the crimped conjugate fiber of the present invention, the first component contains polybutene-1 and linear low density polyethylene, and the second component contains a polymer having a melting peak temperature at least 20° C. higher than the melting peak temperature of the polybutene-1 or a polymer having a melting initiation temperature of 120° C. or higher, and accordingly the fiber exhibits excellent spinnability, stretchability, crimp formability, and like properties. Accordingly, use of the crimped conjugate fiber of the present invention enables a conjugate fiber that has excellent bulk recovery properties and excellent thermal processability with which pieces of the fiber can be strongly thermally bonded to each other even in low-temperature thermal bonding processing as well as a fiber assembly and a fiber product that use the conjugate fiber to be obtained.

[0020]A nonwoven fabric that uses the crimped conjugate fiber of the present invention has both excellent initial bulk and excellent bulk recovery properties, and can be suitably used for cushioning materials and like hard stuffing, hygienic materials, packaging materials, filters, materials for cosmetics, women's brassiere pads, shoulder pads, and like low-density nonwoven fabric products. Also, the crimped conjugate fiber of the present invention can be suitably used for wadding for various pieces of bedding such as mattresses and blankets and various clothes due to the sufficient elasticity and repulsive force of the fiber itself.

Problems solved by technology

However, since this polyesterether elastomer is a copolymer of a hard polyester and a soft ether, and contains a soft component having low thermal resistance, this polyesterether elastomer is readily thermally softened, and the nonwoven fabric undergoes bulk reduction, or so-called sagging, during thermal processing.

As a result, a conjugate fiber in which such a polyesterether elastomer is used as a sheath component is problematic in that the initial bulk when formed into a nonwoven fabric is small, only giving a highly dense nonwoven fabric, and its applications are thus limited.

Furthermore, such a nonwoven fabric being compressed while being heated, or such a nonwoven fabric being repeatedly compressed is problematic in that, for example, the points where pieces of the fiber are bonded to each other and the fiber itself collapse or bend, and the fiber strength is impaired, and thus the hardness of the nonwoven fabric is significantly lower than that of the original nonwoven fabric.

However, while the initial thickness (initial bulk) of the nonwoven fabric is large, the bulk recovery properties, in particular the initial bulk recovery properties immediately after load removal, are not sufficient, and thus there is a problem in that its applications are limited.

The conjugate fiber disclosed in Patent Documents 4 and 5 is problematic in that, when a fiber web that uses the conjugate fiber is processed into a nonwoven fabric in which pieces of the component fiber are bonded to each other by thermal processing, or when pieces of the resulting nonwoven fabric are bonded to each other by thermal processing, since the so-called sheath component that occupies for most of the fiber surface is composed of polybutene-1 and polypropylene, which has a higher melting point than polybutene-1, a phenomenon occurs in which the apparent melting point of the sheath component is increased, and thermal bonding properties in a heat treatment at a low temperature and the strength of the nonwoven fabric after thermal bonding are not sufficient, and it is also difficult to adjust the temperature conditions for thermal bonding processing.

In addition to Patent Documents 1 to 5, extensive research has been made on a nonwoven fabric having excellent bulk recovery properties, a conjugate fiber suitable for such a nonwoven fabric having excellent bulk recovery properties, a nonwoven fabric that uses such a fiber, and the like, but there is still a problem in that deterioration of bulk recovery properties is observed when a load is applied repetitively, and a fiber and a nonwoven fabric that are suitable for use in applications such as cushioning materials for which a high level of bulk recovery properties are needed even after being repetitively compressed are not obtained.

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