JPH02191718A - Heat bondable conjugate yarn - Google Patents

Abstract

PURPOSE:To obtain the title conjugate yarn having high crimp developing properties, containing bulkiness and recovery of elasticity, by arranging two kinds of polymers having different melting points on a concentric sheath part and core part and providing specific eccentric ratio and hollow ratio. CONSTITUTION:The aimed yarn which is conjugate yarn comprising two kinds of polymers having melting points with >=20 deg.C difference, forming a hollow core part 1 of a high-melting polymer such as polypropylene of the two polymers and a sheath part 2 of a low-melting polymer such as polyethylene, making the core part and the hollow core part 1a in the core part eccentric based on the sheath part and providing 0.1-0.7 eccentric ratio (ratio of distance between center of the sheath part and center of the core part and radius of the core part) of the core based on the sheath part, 0.1-0.7 eccentric ratio (ratio of distance between center of the sheath part and the center of the hollow part and radius of the core part) of the hollow part based on the sheath part and 5-40wt.% hollow ratio of the hollow part based on the core part.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a sheath-core type thermally bondable conjugate fiber, which is suitable for use in nonwoven fabrics.

(Prior art) A thermoadhesive composite fiber in the form of a sheath-core type, which is made of a polymer with a melting point difference of 2fjJ, has excellent bulkiness and elastic recovery, and is suitable for use in nonwoven fabrics, and its core is formed hollow. something is known. In this composite fiber, the core polymer has a hollow portion in the fiber axis direction, the adhesive component polymer forms a sheath portion, and the core portion is arranged eccentrically with respect to the sheath portion.

The hollow portion is formed concentrically with respect to the sheath portion and eccentrically with respect to the core portion.

(Problem to be solved by the invention) After the above-mentioned heat-adhesive composite fiber is spun and drawn.

The tow is mechanically crimped, subjected to a relaxing heat treatment, then cut to the desired length to form staples, and then carded into a web.

The conventional hollow heat-adhesive conjugate fibers are processed into a non-woven fabric by laminating the required number of sheets, heat-setting and melting the sheath parts to bond the core parts to each other.

Since the hollow part is formed concentrically with respect to the sheath part, the web is not sufficiently crimped during heat setting.
There was a problem that the resulting nonwoven fabric had poor bulkiness.

The present invention provides a heat-adhesive conjugate fiber that is excellent in crimp development during heat setting, and can be used to produce a nonwoven fabric that is rich in bulk and has good elastic recovery properties.

(Means for Solving the Problems) The heat-adhesive composite fiber of the present invention is composed of two types of polymers having a melting point difference of 20°C or more, and the high melting point polymer forms the hollow core 1. However, in the heat-adhesive composite fiber in which the sheath portion 2 is formed of a low-melting point polymer, the core portion 1 and the hollow portion 1a in the core portion 1 are both arranged eccentrically with respect to the sheath portion 2, and the sheath portion 2 is The eccentricity ratio of the core part 1 to the part 2 (the ratio d□/R of the distance d1 between the center of the sheath part 2 and the center of the core part 1 to the radius R of the core part 1), and the ratio of the hollow part 1a to the sheath part 2 Eccentricity ratio (distance between the center of the sheath part 2 and the center of the hollow part 1a d
, and the radius R of the core 1 (d, /R) are each 0.1.
~0.7, and the hollow ratio of the hollow portion 1a to the core portion 1 is 5 to 40%.

In this invention, polypropylene, polyethylene terephthalate, etc. are used as the high melting point polymer constituting the hollow core 1, and low melting point polymers constituting the sheath 2 include high density, medium density, Low-density polyethylene, ethylene/vinyl acetate copolymer, polypropylene, etc. are used.

The area ratio of the core portion 1 and the sheath portion 2 is 172 to
2/1 is preferable.The hollowness ratio of the hollow part 1a to the core part 1 is the cross-sectional area of the hollow part 1a.

It is expressed as a ratio (%) of the cross-sectional area of the core part 1 and the cross-sectional area of the hollow part 1a to the total area. It is preferable that the centers of the core part 1 and the hollow part 1a are located on one side of a straight line, and it is particularly desirable that the center points of the core part 1, the hollow part 1a, and the sheath part 2 are aligned in a straight line.

(Function) The heat-adhesive composite fiber of the present invention is mechanically crimped and heat-relaxed in the same manner as before, then carded to form a web, and the resulting webs are laminated and bonded by heating. However, since both the sheath part 2 and the hollow part 1a are eccentric with respect to the core part 1, the crimp that occurs during the bonding process increases. That is, since the center of the sheath part 2 is offset from the center of the core part 1, the composite fiber develops crimping due to the heating during the bonding process, and in the process of developing the crimping, the sheath part 2 melts, After this melting, the hollow part 1a is eccentric with respect to the core part 1, so as the sheath part 2 melts, the sheath part 2
The core portion 1 released from the bundle exposure exhibits three-dimensional crimp due to the structural anisotropy of the eccentricity of the hollow portion 1a, and as a result, a nonwoven fabric with high bulkiness is obtained. Especially the core part 1. When the centers of the hollow portion 1a and the sheath portion 2 are arranged on a straight line, the single-fold contraction is maximized. Since the core part 1 constituting this nonwoven fabric has a hollow part 1a, the single bending moment becomes large, and the bulkiness and elastic recovery properties are improved. However, the eccentricity ratio d, /R of the core part 1 with respect to the sheath part 2 and the eccentricity ratio of the hollow part 1a with respect to the sheath part 2 dz/R
If each is less than 0.1, there is no effect of eccentricity, and the expression of crimp is insufficient.5 On the other hand, if it exceeds 0.7, the core part 1 is moved from the sheath part 2, and the core part l to hollow part 1a
becomes easily exposed, and elastic recovery properties decrease. In addition, if the hollowness ratio of the hollow part 1a to the core part 1 is less than 5%, there is no effect of providing the hollow part 1a, the bending moment as a fiber becomes small, the elastic recovery property is insufficient, and on the contrary
If it exceeds this, the hollow portion 1a tends to collapse under high loads, resulting in insufficient bulkiness and elastic recovery.

Note that in the relaxation heat treatment after mechanical crimping, the treatment temperature is preferably set at a low temperature, for example, 60 to 80° C., to suppress the development of crimping and facilitate carding.

(Example) As a high melting point polymer, the melting point is 264°C and the intrinsic viscosity is 0.63.
The above polyethylene terephthalate was heated at 295°C, and the high density polyethylene was heated at 265°C. Each was melt-extruded and continuously spun at a discharge rate ratio of 50/50 and a spinning temperature of 285°C.
The obtained undrawn yarn was drawn under predetermined conditions to produce five types of heat-adhesive conjugate fibers, which were then mechanically crimped in a stuffer box and subjected to relaxing heat treatment at 70°C for 10 minutes. This was cut into 51-length staples, placed in a card machine to make a card web, and the card web was treated with hot air at 140° C. for 1 minute under no load to obtain a nonwoven fabric. The physical properties of the fiber and nonwoven fabric under the manufacturing conditions of 1 Mi are shown in the table below.

In Table 1, the thickness A of the nonwoven fabric is a value measured under a load of 2 g/d, and the thickness B is a value measured after being left for 5 days with a load of 2 g/cd applied. Further, the core eccentricity ratio is the eccentricity ratio d, /R of the core 1 to the sheath 2, and the hollow eccentricity ratio is the eccentricity ratio d2/R of the hollow part 1a to the sheath 2.
It is.

As is clear from the table above, the heat-adhesive composite fiber of Example 1.2 of the present invention has excellent number of shrinkages per roll and shrinkage ratio, and has a large thickness A and thickness B when processed into a nonwoven fabric. , has excellent bulkiness and elastic recovery. On the other hand, in Comparative Example 1, the hollow part eccentricity ratio is zero, so Example 1,
Compared to Example 2, there is less crimp and the thicknesses A and B of the nonwoven fabric are smaller, and since Example 2 does not have a hollow part, it has even poorer bulkiness.

(Effects of the Invention) The thermoadhesive conjugate fiber of the present invention has a melting point of the sheath portion at least 20° C. lower than that of the core portion, and is therefore suitable for use in manufacturing nonwoven fabrics. Moreover, since both the core and the hollow part in the core are eccentric with respect to the sheath, when forming a web and thermally bonding it, it has a high degree of crimping and is highly bulky. 1. A nonwoven fabric with good elastic recovery properties can be obtained. In addition, during the relaxing heat treatment after applying one machine crimp, the treatment temperature is set low to suppress the occurrence of crimp.

It is possible to prevent a decline in card machine passability.

The obtained nonwoven fabric has good elastic recovery properties due to the presence of a hollow portion in the core.

[Brief explanation of the drawing]

The drawing is a cross-sectional view of an embodiment of the invention. 1: Core portion, 1a: Hollow portion, 2: Sheath portion. Patent applicant: Toyobo Co., Ltd. Agent: Patent Attorney, Yoshi 1) Ryo Tsukasa

Claims (1)

[Scope of Claims] [1] Consists of two types of polymers whose melting points differ by 20°C or more, the polymer with a high melting point forming a hollow core, and the polymer with a low melting point forming a sheath. In the heat-adhesive composite fiber to be formed,
Both the core and the hollow part in the core are arranged eccentrically with respect to the sheath, and the eccentricity ratio of the core to the sheath is (
The ratio of the distance between the center of the sheath and the center of the core to the radius of the core), and the eccentricity ratio of the hollow to the sheath (the distance between the center of the sheath and the center of the hollow and the radius of the core) A heat-adhesive conjugate fiber, characterized in that the ratio of the hollow portion to the core portion is from 0.1 to 0.7, and the hollow ratio of the hollow portion to the core portion is from 5 to 40%.