Wholly aromatic polyamide fiber and process for producing the same

Abstract

A wholly aromatic polyamide fiber which has excellent mechanical properties (toughness factor) and can be produced while attaining a satisfactory operation stability in the fiber formation step. The fiber comprises 100 parts by mass of a wholly aromatic polyamide and 0.05 to 20 parts by mass of particles of a lamellar clay mineral, e.g., hectorite, saponite, stevensite, beidellite, montmorillonite, or swelling mica.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to wholly aromatic polyamide fibers containing a layer-structured clay mineral, and a production process thereof. More particularly, the present invention relates to wholly aromatic polyamide fibers containing a layer-structured clay mineral and having improved mechanical characteristics, particularly toughness, and a production process thereof. [0003] 2. Description of the Related Art [0004] Considerable interest has been focused on the imparting of high added value to polymers and enhancement of their performance in recent years. Compound materials obtained by containing a filler in a polymer have been actively developed in order to impart high added value and high performance to polymers. In the past, fibrous or acicular fillers have been used as reinforcing fillers for the purpose of improving the mechanical characteristics and heat resistance of polymers and, as a result, known pol...

AI Technical Summary

Benefits of technology

[0012] An object of the present invention is to provide wholly aromatic polyamide fibers having high mechanical properties, and a high toughness factor in particular, that can be spun with satisfactory process stability in a spinning process, and a process for industrially producing the same.

[0013] According to research conducted by the inventors of the present invention, drawn and oriented wholly aromatic polyamide fibers obtained by wet spinning and drawing a spinning liquid containing a wholly aromatic polyamide and a layer-structured clay mineral were found to have superior mechanical characteristics, and particularly superior toughness factor. More surprisingly, it was also found by the inventors of the present invention that, instead of completely uniformly dispersing each layer of the layer-structured clay mineral in the fibers, by scatteringly distributing a plurality of regions having a relatively high layer-structured clay mineral distribution density in the aromatic polyamide polymer matrix that composes the particles, the effect of improving the mechanical characteristics of the fibers, and particularly the toughness factor, can be further enhanced by the layer-structured clay mineral particles.

Problems solved by technology

However, the strength of a compound material is known to be greatly affected not only by the strength of the polymer serving as the matrix of the compound material as well as the strength of the filler itself, but also by the interface adhesion between the filler and polymer, and the quality of the wettability of the polymer to the filler has an effect not only on the ease of production, but also on the strength of the finished product.

For reasons such as these, it is not always possible to obtain a compound material having superior strength even if a filler or polymer having high strength and elasticity is used for the material.

Moreover, compound materials containing a filler are generally known to have the disadvantage of low ultimate elongation.

Although a known example of a process for improving fiber mechanical strength involves improving the degree of orientation of fibers by drawing, in the case of using such a process, as ultimate elongation is known to decrease with the improvement tensile strength, it becomes difficult to produce filaments having a high toughness factor.

However, these are all targeted at thermoplastic polyamide, and the use of a layer-structured clay mineral for non-thermoplastic polyamide, in the form of wholly aromatic polyamide fibers, is not disclosed in these patent documents.

However, the improvement of the mechanical properties of wholly aromatic polyamide fibers by containing a layer-structured clay mineral as filler, and wholly aromatic polyamide fibers containing a layer-structured clay mineral as filler and having a high toughness factor as a result of thereof, are not known from documents of the prior art.

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