JP6807789B2 - High-strength hollow fiber - Google Patents

Description

The present invention relates to a high-strength hollow fiber having high strength while having a hollow structure having voids inside.

Fibers made of synthetic resin are widely used for clothing and various industrial applications. Among them, high-strength synthetic fibers are used in various fields in order to make the best use of their physical characteristics. However, there is a problem that the stronger the strength, the more rigid the fiber becomes, which makes production and processing difficult.

On the other hand, as the synthetic fiber, hollow fiber is widely used as a means for enhancing wearing comfort from the viewpoint of physical properties such as heat retention and flexibility. However, it is difficult to process high-strength synthetic fibers, and it is very difficult to obtain hollow fibers, particularly hollow fibers having sufficiently small internal voids.

For example, Patent Document 1 discloses a method for producing an aramid (aromatic polyamide) hollow fiber in which a clarified solution in which insoluble particles are separated is used as a spinning stock solution for wet spinning. It was difficult to produce the hollow fiber, and the hollow fiber had an inner diameter of 0.5 mm and a film thickness of 10 μm at most.

JP-A-2002-20928

An object of the present invention is to provide a high-strength hollow fiber having high strength while having a hollow structure having voids inside.

The high-strength hollow fiber of the present invention is a fiber in which the synthetic resin is made of a para-aromatic polyamide resin , has a hollow structure having a diameter of 100 μm or less, and has a strength of 10 cN / dtex or more. Further, it is preferable that the hollow portion has a film thickness of 10 to 35 μm and the synthetic resin is a copolymerized aromatic polyamide resin.

According to the present invention, there is provided a high-strength hollow fiber having high strength while having a hollow structure having voids inside.

Schematic diagram of the spinneret for hollow fibers used in Example 1 of the present invention. Schematic diagram of the spinneret for hollow fibers used in Example 2 of the present invention.

The high-strength hollow fiber of the present invention is a fiber in which the synthetic resin is made of a para-aromatic polyamide resin , has a hollow structure having a diameter of 100 μm or less, and has a strength of 15 cN / dtex or more.

The synthetic resin constituting the fiber of the present invention is a resin having fiber moldability, and is a resin capable of forming fibers by discharging a solution containing a resin component from a spinneret. Above all, it is preferable that the synthetic resin is a total aromatic polyamide resin from the viewpoint of physical properties such as fiber strength.

As described above, the total aromatic polyamide preferably used in the present invention is a polymer in which one or more divalent aromatic groups are linked by an amide bond, and the aromatic group has two or more aromatic groups. A ring may be present, and the aromatic ring may be directly bonded or may be bonded via oxygen or sulfur. Further, the hydrogen atom of the divalent aromatic group may be substituted with a halide, a lower alkyl group, or a phenyl machine.

Such a totally aromatic polyamide that can be preferably used in the present invention can be obtained, for example, by reacting an aromatic dicarboxylic acid chloride component and an aromatic diamine component in a solution in an amide-based polar solvent. Is. In particular, from the viewpoint of strength, a para- based total aromatic polyamide is preferable, and from the viewpoint of easily adjusting the hollow shape when obtaining hollow fibers from a polymer solution, a copolymerized total aromatic polyamide is preferable. preferable.

Here, the aromatic dicarboxylic acid chloride component used in the production of the total aromatic polyamide is not particularly limited, but is preferably terephthalic acid chloride from the viewpoint of the physical characteristics of the obtained fiber. Similarly, the aromatic diamine component used in the production of the total aromatic polyamide is not particularly limited, but from the viewpoint of the physical characteristics of the obtained fiber, p-phenylenediamine and 3,4'-diaminodiphenyl ether are used. It is preferable to use them in combination. By using such a para- based copolymerized total aromatic polyamide, it is possible to maintain the strength and the hollow shape at a high level.

The ratio of the aromatic dicarboxylic acid chloride component to the aromatic diamine component in the total aromatic polyamide that can be preferably used is 0.99 to 1.10 as the molar ratio of the aromatic dicarboxylic acid chloride component to the aromatic diamine component. It is preferably in the range. Further, it is preferably in the range of 0.95 to 1.05. If the molar ratio of the aromatic dicarboxylic acid chloride component is out of this range, the progress of the reaction with the aromatic diamine component may be hindered and the degree of polymerization may be lowered.

The high-strength hollow fiber of the present invention is a fiber made of the synthetic resin as described above and has a hollow structure having a diameter of 100 μm or less. Further, it is preferably in the range of 3 to 80 μm, and particularly preferably in the range of 10 to 30 μm. If the diameter of the hollow portion is larger than 100 μm, the cross-sectional shape of the fiber is easily crushed, and the effect of the hollow fiber cannot be obtained. Further, if the diameter of the hollow portion is too small, the amount of air contained is reduced, the heat retention property is lowered, and the properties peculiar to the hollow fiber such as sweat absorption cannot be exhibited. Further, when the dope is discharged as in the present invention and then solidified through the air gap to form a fiber shape, the hollow portion is crushed and stable production cannot be performed.

In the high-strength hollow fiber of the present invention, the film thickness of the hollow portion is preferably 10 to 35 μm. Further, it is preferably in the range of 15 to 35 μm, and particularly preferably in the range of 20 to 35 μm. If the film thickness of the hollow fiber is small, the strength of the fiber is lowered, and the fiber tends not to be a high-strength fiber. Further, if the film thickness is too large, not only the hollow structure is not formed and the peculiar physical properties cannot be obtained, but also the hollow fiber cannot be stably produced.

The high-strength fiber needs to have a strength of 10 cN / dtex or more, but more preferably 12 cN / dtex or more, and particularly preferably in the range of 15 to 30 cN / dtex. Normally, it was difficult to obtain hollow fibers with such high-strength fibers, but in the present invention, the desired high-strength hollow fibers can be obtained by the production method described below.

Another method for producing a high-strength hollow fiber of the present invention is to discharge a synthetic resin dissolved in a solution into the air from a plurality of divided caps to form a fibrous material having a hollow structure, and after wet solidification, 5 It is a manufacturing method characterized by stretching more than twice.

Here, as the synthetic resin for forming fibers, the above-mentioned resin having fiber moldability can be used, and in the production method of the present invention, it is preferable to dissolve such a resin in a solution and use it.

Among them, the resin preferably used is a totally aromatic polyamide resin from the viewpoint of physical properties such as fiber strength. Among them, a para- based total aromatic polyamide is preferable from the viewpoint of strength, and a copolymerized total aromatic polyamide is preferable from the viewpoint of easily adjusting the hollow shape when obtaining hollow fibers from a polymer solution. preferable. In particular, the aromatic dicarboxylic acid chloride component is preferably terephthalic acid chloride, and the aromatic diamine component is preferably a combination of p-phenylenediamine and 3,4'-diaminodiphenyl ether. By using such a para- based copolymerized total aromatic polyamide, it is possible to maintain the strength and hollow shape of the finally obtained fiber at a high level. The ratio of the aromatic dicarboxylic acid chloride component to the aromatic diamine component is preferably in the range of 0.99 to 1.10 as the molar ratio of the aromatic dicarboxylic acid chloride component to the aromatic diamine component. Further, it is preferably in the range of 0.95 to 1.05.

In the production method of the present invention, the solvent for polymerizing the resin forming such fibers or when the resin is used for dissolution for forming the fibers is preferably an amide-based polar solvent. Of these, it is most preferable to use highly soluble N-methyl-2-pyrrolidone, which is suitable for producing a total aromatic polyamide. It is also a good method to neutralize the hydrochloric acid in the system by adding a basic inorganic compound after the completion of the polymerization reaction.

In the method for producing a high-strength hollow fiber of the present invention, a synthetic resin dissolved in such a solution is discharged into the air from a plurality of divided caps to form a fibrous material having a hollow structure. The base for forming such hollow fibers preferably has a shape as shown in FIGS. 1 and 2, for example.

The synthetic resin solution discharged from the spinneret is landed on the coagulating liquid through an air gap and coagulated, and becomes a fiber shape by so-called wet coagulation. In the manufacturing method of the present invention, there is an air gap immediately after the spinneret is discharged, and the fibers are preliminarily fiberized in the air. The components discharged from the plurality of time-divided caps are fused to form a hollow structure. However, it is preferable that the air gap is short for the purpose of ensuring the final physical characteristics of the fiber, and it is preferable that the distance from the discharge to the coagulating liquid is short in order to maintain the hollow structure inside the fiber. However, if the air gap is too short, the coagulating liquid tends to adhere to the mouthpiece due to the shaking of the coagulating liquid surface, resulting in poor discharge. Further, the air gap length is preferably 5 mm or more and 30 mm or less. In particular, it is more preferably in the range of 10 mm or more and 25 mm or less.

Further, in the production method of the present invention, the resin having fiber moldability as described above is wet-coagulated, and the composition of the coagulating liquid is when synthetic fibers, particularly aromatic polyamide fibers, are used. It is preferably a poor solvent for the total aromatic polyamide. The composition does not necessarily have to be single, and for example, a mixed solution of NMP and water may be used. The temperature of the coagulating liquid is preferably 30 ° C. or higher. More preferably, it is 60 ° C. or higher. However, if the temperature of the coagulating liquid is too high, the coagulating liquid volatilizes, and mist-like droplets adhere to the base surface to cause ejection failure. Therefore, 100 ° C. or lower is appropriate. The higher the temperature of the coagulant, the easier it is to form a hollow structure. This is because the faster the solidification rate, the easier it is to maintain the shape at the time of discharge.
After that, it is preferable to sufficiently remove the solvent from the undrawn yarn formed by further carrying out a washing step.

Then, after the coagulated yarn is pulled up from the coagulating liquid, it is necessary to stretch the coagulated yarn five times or more in the method for producing a high-strength hollow fiber of the present invention. It is also preferable to dry the undrawn fibers before stretching. In the production method of the present invention, it has become possible to obtain sufficiently fine hollow fibers by stretching. Further, by stretching in this way, the molecular chains can be oriented and the final fiber physical characteristics can be improved. The method of stretching is not particularly limited, and various methods such as washing with water in a solidified yarn state, boiling water stretching, and heating and stretching in a dry yarn state can be adopted.

It is essential that the draw ratio is 5 times or more, but more preferably 8 times or more, particularly preferably in the range of 8 to 14 times. By controlling the draw ratio, it is possible to control the physical characteristics such as the elongation and strength of the obtained hollow fiber.

The stretching temperature is preferably in the range of 500 to 600 ° C., particularly when the hollow fiber has a glass transition temperature, at a temperature of + 220 ° C. or lower of the glass transition temperature, particularly + 180 ° C. or lower of the glass transition temperature. It is preferable to do so.

The high-strength hollow fiber of the present invention is, for example, a fiber obtained by such a manufacturing method, which is hollow but has high strength, is excellent in heat retention, texture, and reinforcing effect, and is used for various clothing and industrial materials. It has become possible to use it widely.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to the following Examples and Comparative Examples.

(1) Measurement of fineness 100 m of the obtained fiber was sampled using a measuring machine, and its mass was measured. The obtained value was multiplied by 100 to obtain the value of fineness.

(2) Measurement of fiber tensile strength Using a tensile tester (manufactured by INSTRON, "INSTRON", model: 5565), using a thread test chuck, based on the procedure of ASTM D885, the fiber is tensioned under the following conditions. The intensity was measured.
[Measurement conditions] Temperature: Room temperature, Test length: 75 mm, Tensile speed: 250 mm / min, Chuck distance: 500 mm

(3) Measurement of outer diameter of hollow portion A cross-sectional image of the obtained hollow fiber was photographed with a microscope (“Digital Microscope VHX-2000” manufactured by KEYENCE CORPORATION), and the diameter of the hollow portion was calculated from the image.

(4) Measurement of film thickness of hollow fiber In the same manner as in (3) above, a cross-sectional image of the obtained fiber is taken with a microscope (“Digital Microscope VHX-2000”), and the image shows the outer wall of the fiber. The thickness was calculated. It was measured at the point where the thickness of the outer wall of one fiber was maximized, and the value was taken as the thickness of the outer wall of the fiber.

[Example 1]
Terephthalic acid chloride is used as the aromatic dicarboxylic acid chloride component, p-phenylenediamine and 3,4'-diaminodiphenyl ether are used as the aromatic diamine component, and N-methyl-2-pyrrolidone (NMP) is used as the solvent for the polymerization. ) Was used to obtain a synthetic resin solution (polymer solution) for spinning a para -copolymerized aromatic polyamide having a polymer concentration of 6% by weight. This polymer solution is discharged from a discharge hole having the shape shown in FIG. 1 from a mouthpiece having 15 hollow discharge fibers, coagulated in an aqueous solution having an NMP concentration of 30% through a 10 mm air gap, and then washed with water. After drying, it was stretched 10 times at a temperature of 530 ° C. to obtain high-strength hollow fibers made of a totally aromatic polyamide resin. The glass transition temperature of this fiber was 370 ° C. Table 1 shows the physical characteristics of the obtained high-strength hollow fibers.

[Example 2]
In the same manner as in Example 1, however, the shape of the discharge hole was changed from that of FIG. 1 to that of FIG. 2, and the discharge amount of the polymer solution was set to 1/3 of that of Example 1 to obtain a high-strength hollow fiber. Table 1 also shows the shape and physical properties of the obtained high-strength hollow fibers.

[Comparative Examples 1 and 2]
Hollow fibers shown in Table 1 were obtained by melt spinning using a polyethylene terephthalate (polyester) resin (Comparative Example 1) and a nylon 6 resin (Comparative Example 2). Although the fiber satisfied the diameter and film thickness of the hollow portion, the strength was insufficient. The physical characteristics are also shown in Table 1.

Claims (3)

A high-strength hollow fiber in which the synthetic resin is a fiber made of a para-aromatic polyamide resin , has a hollow structure having a diameter of 100 μm or less, and has a strength of 10 cN / dtex or more. The high-strength hollow fiber according to claim 1, wherein the hollow portion has a film thickness of 10 to 35 μm. The high-strength hollow fiber according to claim 1 or 2, wherein the synthetic resin is a copolymerized aromatic polyamide resin.

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