JP3037791B2 - Polyolefin-based split fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin-based split short fiber having excellent processability.

[0002]

It is known that split fibers can be obtained by combining two or more polymers which are incompatible with each other. JP-A-2-169720 discloses a combination of a polyolefin and a polyester or nylon, and JP-A-2-169723 discloses a combination of a polyester and a polyamide.

[0003]

The production of nonwoven fabrics, carpets and the like using staple fibers requires a carding step, and the single fiber fineness that can be carded is generally limited to 1 denier. For smaller deniers, special carding techniques and conditions must be employed. In the case of a maker mainly using thick denier carpets, the lower limit tends to be further thicker. By the way, the conventional split fibers obtained by simply compounding mutually incompatible polymers have a drawback in that the splitting occurs in the carding step and, in the worst case, in the raw cotton production step, making the carding difficult. As an attempt to solve such a drawback, for example, as described in JP-A-2-169722, a polyester fiber is copolymerized with a metal salt sulfonate in a composite fiber of polyamide and polyester, and further steam or hot water is used. Stretched in 10
A split fiber characterized by being subjected to constant-length heat treatment at 0 to 160 ° C. dry heat has been proposed. However, this split fiber also uses an expensive raw material called a special copolymer,
It is still unsuitable for commercial production, such as the need to perform specific stretching and heat treatment. Furthermore, since the conventional split fibers are composed of composite fibers obtained by combining different kinds of polymers, there is a drawback that the obtained product is a cotton blend of these different kinds of polymer fibers and the use thereof is limited.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies to improve these disadvantages of the conventional split short fibers,
The present inventors have found that the intended purpose can be achieved by compound spinning of polypropylene and a mixture of polypropylene and polyethylene in a parallel type, and have completed the present invention. That is, the present invention provides a first component comprising polypropylene,
Polypropylene 50 to 20% by weight and polyethylene 50 to
The second component consisting of 80% by weight is arranged in parallel so that the contact length between the first component and the second component in the fiber cross section is 0.95 to 1.10 times the fiber diameter. Characterized in that it is a polyolefin-based split short fiber.

The polypropylene used as the first component in the present invention is a crystalline polymer containing propylene as a main component. In addition to a propylene homopolymer, a random copolymer or a block copolymer containing ethylene, butene-1 or the like as a copolymer component. Can be used. In the present invention, the second component is used in a mixture of polypropylene and polyethylene. As this polypropylene, a crystalline polymer similar to the polypropylene used as the above-mentioned first component is used, but it is not necessary to be the same type of polymer as the first component. Also, as polyethylene, low density polyethylene,
Medium density polyethylene, high density polyethylene, linear low density polyethylene and the like can be used. Stabilizers, colorants, fillers and the like which are usually added to these resins can be added to such an extent that the object of the present invention is not impaired.

[0006] The content of polyethylene in the second component is 50
The reason is that the content of polyethylene is 8% by weight.
If the content exceeds 0% by weight, division occurs in the carding step and the raw cotton production step. If the polyethylene content is less than 50% by weight, division does not occur in the carding step or the raw cotton production step, but a very large physical external force is required in the final step. This is because the fiber may be cut off at the same time. The reason why the contact length between the first component and the second component in the fiber cross section is limited to 0.95 to 1.10 times the fiber diameter is that when the length is less than 0.95 times, the contact length is divided in the carding step or the raw cotton manufacturing step. If the ratio exceeds 1.10 times, no division occurs in the carding process or the raw cotton production process, but a very large physical external force is required in the final process. This is because the fiber may be cut before. Obtaining such a conjugate fiber having a fiber cross section can be easily carried out by using a usual parallel type conjugate spinning apparatus and adjusting the conjugate ratio and melt viscosity of both components.

[0007]

The present invention will be further described with reference to Examples and Comparative Examples. In addition, the division | segmentation rate of the fiber used in each example was measured by the following method. The sample is embedded in wax and cut with a microtome at a right angle to the fiber axis to obtain a 10 μm thick sample section. This is observed with a microscope, and the division ratio is determined according to the following definition. Observing n fibers (n is 100 or more) and assuming that the number of undivided fibers is m, the division ratio (%) of the divided short fibers = ((nm) / n) × 1
Examples 1 to 8 and Comparative Examples 1 to 3 A parallel type composite fiber was melt-spun with a combination of various polymers shown in Table 1 and stretched 3.5 times with a hot roll at 95 ° C. After applying mechanical crimping with a stuffer box, the fiber was cut to a fiber length of 64 mm to obtain raw cotton of each split short fiber. Table 1 shows the composition, component ratio, boundary / diameter ratio, and fiber denier of each component. Then each raw cotton b - La - Ca - Ca in at de machine 50 m / min speed - and Deingu, a web having a mass per unit area of 180 g / m ^2, followed by Ferutoni the web - 300 present in punching machine having a dollar / cm
After processing at a needle density of ² , a punching machine having a crown needle was used to process at a needle density of 700 needles / cm ² . Table 1 shows the degree of fiber division after raw cotton, after carding, and after needle punching.

[0008]

[Table 1]

The physical properties of the polymers indicated by the symbols in the table are as follows: PP1: polypropylene, MFR = 30, melting point 165
° C, homopolymer PP2: polypropylene, MFR = 7, melting point 161
° C, random copolymer containing ethylene 0.4% PE1: High density polyethylene, MI = 16, melting point 13
4 ° C PE2: linear low density polyethylene, MI = 6, melting point 1
26 ° C

[0010]

The split staple fiber of the present invention does not split at the time of raw cotton production or at the time of passing through a process such as carding, and has a good process-passing property. In addition, division can be performed by mechanical impact processing such as needle punching or water jet. The nonwoven fabric using the split short fiber of the present invention has excellent drapability with a flexible touch and polyolefin 1
It is made of 00% material and has excellent chemical resistance, heat retention and the like.

Claims (1)

(57) [Claims] 1. A first component comprising polypropylene, 50 to 20% by weight of polypropylene and 50 to 80% of polyethylene.
% By weight of the first component in the fiber cross section.
The contact length between the component and the second component is 0.9 to the fiber diameter.
An olefin-based split short fiber, which is arranged in a parallel type so as to be 5 to 1.10 times.