JP3070259B2 - Polyolefin-based splittable 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 splittable fiber which is composed of only a polyolefin and has an excellent process passage property.

[0002]

2. Description of the Related Art When manufacturing nonwoven fabrics and the like, there is a step of carding staple fibers to form a web.
In general, the lower limit of the fineness of carding is 1 denier, and in the case of finer fibers, special carding techniques and conditions must be adopted. In the case of producing carpet, since the content of the thick denier fiber is large, the lower limit tends to be further thicker. In recent years, a softer hand has been required, and in order to obtain a nonwoven fabric using fibers of fineness, there is a strong demand for fibers of cardable fineness. Conventionally,
2. Description of the Related Art There is known a method of obtaining fine denier fibers by splitting splittable fibers obtained by complex spinning two or more polymers 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. By the way, a conventional splittable fiber obtained by simply spinning a polymer which is incompatible with each other, has a denier of 1 denier or more at the time of spinning. There is a disadvantage that division occurs in a raw cotton manufacturing process such as cutting and carding cannot be performed. Further, since the conventional splittable fiber is a combination of different types of polymers, the resulting product is a cotton blend of those polymers. At present, fibers such as polyamide and polyester combined with this are inevitably mixed and a desired product cannot be obtained. Attempts to overcome these drawbacks of splittable fibers include the combination of a plurality of α-polyolefins having a specific hardness, monomer carbon number and molar ratio (substantially two out of polyethylene, polypropylene, polymethylpentene). (Japanese Patent Laid-Open Publication No. 3-137222). However, even if such a combination is used, there is no problem in a low-speed card machine because of the combination of essentially incompatible polymers.
In high-speed card machines, division occurs during carding, which is unsuitable for commercial production. Further, in the case of a composite fiber obtained by combining polypropylenes or polyethylenes, division in the carding step does not occur, but fine denier fibers cannot be obtained without division in the final step such as needle punching and water needle.

[0003]

A splittable fiber made of 100% polyolefin, which does not cause splitting in processes such as spinning, drawing, and carding, and can be split well in processes such as needle punching and water jetting. I will provide a.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to improve these drawbacks of the conventional splittable fiber, and as a result, have found that the first component consisting of polypropylene contains a specific mixture of polypropylene and polyethylene. The inventor has found that a composite fiber obtained by combining two components has an expected performance, and has completed the present invention. That is, the present invention provides a first component composed of polypropylene and a methyl branch number of 1.5 / 100.
High-density polyethylene having a temperature of 0 C or more is a polyolefin-based splittable fiber comprising a second component consisting of a mixture added to the following amount of polypropylene, both components being constituent units of the fiber cross section. 75 ≦ M × (100−P) ≦ 140 M: Number of methyl branches per 1000 C in high-density polyethylene P: Weight% of high-density polyethylene in second component

The present invention will be described in more detail. The polypropylene used in the present invention is a fiber-forming crystalline polypropylene, not only a homopolymer of propylene,
A copolymer containing propylene as a main component and ethylene or butene-1 as a copolymer component may be used. Further, the polypropylene used for the first component and the polypropylene used for the second component may be the same or different. In the second component used in the present invention, as the polyethylene to be added to the polypropylene, a high-density polyethylene having a number of methyl branches of 1.5 / 1000C or more is used.
High-density polyethylene means that the density is 0.945 g / cm ³
The above polyethylene is produced using a Ziegler catalyst, a chromium oxide catalyst or a molybdenum oxide catalyst. Here, the methyl branch refers to a methyl group directly branched from the main chain of polyethylene, and does not include a methyl group not directly connected to the main chain such as a terminal methyl group of an ethyl branch.
The number of such methyl groups can be determined by a nuclear magnetic resonance spectrum of a carbon atom having a mass number of 13. In addition, 1
000C is the number of carbon atoms in the polyethylene main chain.
It indicates how many methyl groups are branched per 00 carbons. The number of methyl branches in polyethylene is 1.
If the number is less than 5 / 1000C, the spinnability and the fiber properties are significantly deteriorated when blended with polypropylene. The upper limit of the number of methyl branches is not particularly limited, but ease of production,
From the cost, 8 to 9 pieces / 1000C will be the practical upper limit.

[0006] Hitherto, it has been considered that polypropylene and polyethylene are incompatible with each other, so that when resin blending is performed, spinnability is greatly reduced and fiberization cannot be performed. However, in the case of high-density polyethylene having 1.5 / 1000C or more methyl branches, it was found that spinning properties and fiber properties were hardly reduced even if polypropylene and resin were blended. The content of high-density polyethylene in the second component must be within the range of the following formula. 75 ≦ M × (100−P) ≦ 140 M: The number of methyl branches per 1000 C in the high density polyethylene P: The weight% of the high density polyethylene in the second component The reason is that M × (100−P) is 75 If the ratio is less than the above, division occurs in the carding process and the raw cotton manufacturing process. In addition, when the ratio exceeds 140, the division does not occur in the carding process or the raw cotton production process, but a very large force is required when performing the division in the final process, and in an extreme case, the fiber may be broken before the division. . Here, a specific calculation example is shown. For example, the number of methyl branches is 3.0 / 10
When the high density polyethylene of 00C is 60% by weight and the polypropylene is 40% by weight, M × (100−P) =
3.0 × (100−60) = 120, and this composition meets the requirements of the present invention. To the first component and the second component, stabilizers, coloring agents, fillers and the like which are usually added to the polyolefin fiber can be added to such an extent that the object of the present invention is not impaired.

In the splittable fiber of the present invention, various arrangements of the first component and the second component can be considered. For example, the first component and the second component are arranged in a two-layer, two-component parallel type. (FIGS. 1 and 2), those in which the first component and the second component are arranged in a parallel type of a multilayer two-component having three or more layers (FIGS. 3 and 4), and radiation. One in which the first component of the mold shape and the second component are arranged in a shape that complements the radiating portion, or vice versa (FIGS. 5, 6, 7, 8, and 9). And FIG. 9) are typical examples.
Further, the cross-sectional shape of the fiber may be not only a circle but also an irregular shape such as an ellipse, a square, a triangle, or a star. In short, as long as the object of the present invention is to obtain a result excellent in easy division in the final step without division at the time of passing through the process, the arrangement structure and cross-sectional shape thereof are not limited at all. Although the splittable fiber of the present invention is not split in the fiber production step and the carding step, it can be split easily in processing steps such as needle punching and water jet.

[0008]

The present invention will be further described with reference to Examples and Comparative Examples. Each of the spinnerets has a nozzle diameter of 0.6 mm,
The number of nozzles is 350 and the extrusion amount is 200 g / min.
Unified. The evaluation method is as follows.・ Spinnability: The number of yarn breaks per 100 kg of spinning amount is 1
Less than 1 times, 1 times or more and less than 3 times, and 3 times or more, ×. Splitting ratio of splittable fiber: A sample (fiber bundle) is embedded in wax, and cut by a microtome at a substantially right angle to the fiber axis to obtain a 10 μm thick sample section. This is observed with a microscope, and assuming that the number of undivided fibers of 100 or more fibers (n) is m, the division ratio (%) of the splittable fiber = (1−m / n) × 100・ Card passing property: The fiber is 20m / with a roller card machine.
Carding at a speed of min and passing all of the following three items was judged as "good", and if any item was rejected, it was judged as "poor". • The web sinking was that - obtained without the fiber was visually inspected to the cylinder, were taken from that there is no plaque, obtained any of the 10 locations of the web 25c
The weight of m-square specimens must be within ± 15% of the average value.

Examples 1 and 2 and Comparative Examples 1 to 5 By using the first and second components shown in Table 1, side-by-side composite fibers having a cross section shown in FIG. 1 were melt-spun. The component ratio (weight) was 1st component / 2nd component = 50/50. After spinning, 95
The film was stretched 3.5 times with a hot roll at ℃ and mechanically crimped with a stuffer box to obtain splittable fibers. The composition of each component, the component ratio, the value of M × (100−P) in each example,
Table 1 shows the fiber morphology, fiber denier, and spinnability. Next, each fiber was carded with a roller card machine at a speed of 50 m / min to obtain a web having a basis weight of 180 g / m ² . Subsequently, the web was processed at a needle density of 300 needles / cm ² by a punching machine having a felt needle, and then processed at a needle density of 700 needles / cm ² by a punching machine having a crown needle. Table 1 shows the division ratios of raw cotton, after carding, and after needle punching.

Examples 3 and 4 Using the first component and the second component shown in Table 1,
The side-by-side conjugate fiber having the cross section shown in the figure was melt-spun. Component specific weight) was 1 / component = 30/70. Thereafter, stretching, crimping, carding and needle punching were performed in the same manner as in Example 1. Table 1 shows the division ratios of raw cotton, after carding, and after needle punching. Example 5 Using the first and second components shown in Table 1,
The composite fiber having the cross section shown in FIG. 0 was melt spun. The component ratio (weight) was 1st component / 2nd component = 50/50. In the following test, the divided state was tested by treating in the same manner as in Example 1.

[0011]

[Table 1]

The resins indicated by symbols in the table are as follows: PP1: polypropylene, MFR = 15, melting point 165
° C PP2: polypropylene, MFR = 20, melting point 165
° C PE1: High density polyethylene, MI = 23, number of methyl branches = 2.1 / 1000C PE2: High density polyethylene, MI = 16, methyl branches = 4.9 / 1000C PE3: High density polyethylene, MI = 11 , Methyl branch number = 6.7 / 1000C PE4: high density polyethylene, MI = 11, methyl branch number = 1.0 / 1000C

[0013]

The splittable 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, has good processability, and does not use a chemical such as an alkali which may cause a problem such as waste liquid. Division is possible by mechanical impact treatment such as needle punching or water jet. The nonwoven fabric using the splittable fiber of the present invention has excellent drapability with a flexible touch and is made of a 100% polyolefin material, and thus has excellent chemical resistance, heat retention and the like.

[Brief description of the drawings]

1 is an explanatory view illustrating the arrangement of the first and second components of the dividable fibers. One in which both components are arranged in parallel (1), (2). Those in which both components are arranged in parallel with three or more layers (3) and (4). (5) to (10) in which one component is radially arranged in the other component.

Claims (7)

(57) [Claims] 1. A polyolefin system comprising: a first component comprising polypropylene; and a second component comprising a mixture in which high-density polyethylene having a number of methyl branches of not less than 1.5 / 1000 C is added to polypropylene in the following formula. Dividable fibers. 75 ≦ M × (100−P) ≦ 140 M: Number of methyl branches per 1000 C in high-density polyethylene P: Weight% of high-density polyethylene in second component 2. The polyolefin-based splittable fiber according to claim 1, wherein the first component and the second component are arranged in a two-layer two-component parallel type. 3. The polyolefin-based splittable fiber according to claim 1, wherein the first component and the second component are arranged in a three-layer or more multilayer two-component parallel type. 4. The polyolefin dividable fiber according to claim 1 in which the second component by the first component has a split fiber cross section into a plurality. 5. The polyolefin-based splittable fiber according to claim 4, which has a fiber cross section in which a first component in a radial shape and a second component are arranged in a shape complementary to the radiating portion. 6. The polyolefin-based splittable fiber according to claim 1, which has a fiber cross section in which the first component is split into a plurality by the second component. 7. The polyolefin-based splittable fiber according to claim 6, which has a fiber cross section in which a second component of a radial shape and a first component are arranged in a shape complementary to the radiating portion.