Lyocell multi-filament for tire cord and method of producing the same

Abstract

Disclosed is a lyocell multi-filament for a tire cord and a method of producing the same. The method includes i) dissolving mixed powder of cellulose and polyvinyl alcohol in a mixed solvent of N-methyl morpholine N-oxide and water to prepare a dope, ii) extruding the dope using a spinning nozzle including orifices through air gaps into a conical upper coagulation bath to solidify the dope to produce a multi-filament, iii) feeding the multi-filament through a lower coagulation bath to a washing bath, and washing the multi-filament, and iv) drying and oiling the washed multi-filament and winding the resulting multi-filament. At this time, the orifices each have a diameter (D) of 100 to 300 μm, a length (L) of 200 to 2400 μm, and a ratio of the length to the diameter (L / D) of 2 to 8, and are spaced apart from each other at intervals of 2.0 to 5.0 mm. The method provides a lyocell multi-filament having excellent physical properties useful as a tire cord, thereby producing a tire for an automobile having improved driving stability, dimensional stability, and uniformity using the tire cord.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention pertains to a lyocell multi-filament for a tire cord, a method of producing the same, the tire cord and a tire for an automobile using the same. More particularly, the present invention relates to a lyocell multi-filament for a tire cord, which has excellent physical properties for the tire cord, thereby providing a tire with improved driving stability, dimensional stability, and uniformity for an automobile, a method of producing the same, the tire cord and a tire for an automobile using the same. [0003] 2. Description of the Related Art [0004] As well known to those skilled in the art, a material of a tire cord used as a framework constituting a tire is selected from the group consisting of polyester, nylon, aramid, rayon, and steel. In this regard, it is required that the material of the tire cord has the following excellent physical properties: 1) high strength and initial modulus, 2) excel...

AI Technical Summary

Benefits of technology

[0024] Therefore, the present invention has been made keeping in mind the above disadvantages occurring in the prior art, and an object of the present invention is to provide a method of producing a lyocell filament with excellent tenacity and modulus for a tire cord in high yield, thereby producing a tire with improved driving stability, dimensional stability, and uniformity for an automobile.

Problems solved by technology

However, the above materials cannot have all the above excellent physical properties as described above, so the material of the tire cord depends on the intended use of the tire cord.

However, the rayon tire cord has relatively low tenacity and its modulus is greatly degraded by moisture, so it is difficult to control moisture and quality of the tire during the production of the tire including the rayon tire cord.

Additionally, even if the tire including the rayon tire cord is manufactured, when a surface of the tire is damaged and moisture penetrates into the damaged tire, strength and modulus of the tire are reduced, thus being poor in terms of its performance.

However, the lyocell fiber has not been used as the tire cord because of the spinning related problems.

Further, in the case of producing the lyocell fiber, when a solution including NMMO (N-methyl morpholine N-oxide), water, and cellulose at relatively high temperature of 80 to 130° C. is spun in such a way that a spinning nozzle is dipped in a coagulation bath according to the traditional wet spinning method, the solution is too quickly coagulated to secure desirable physical properties.

Additionally, it is difficult to sufficiently vaporize the solvent from a high viscous cellulose solution of about 10000 poises using only the dry spinning method.

However, they are not useful to be directly applied to the production of a lyocell multi-filament, because filaments are apt to adhere to each other because of a great number of filaments, so desired spinning efficiency is not obtained.

As well, the lyocell fiber produced by the above processes has inadequate tenacity and elongation for use as a tire cord.

However, it is difficult to commercialize this process because of various disadvantages, for example the recovery of the coagulation solution containing salts.

Accordingly, this patent is disadvantageous in that it is difficult to secure the tire cord with desired physical properties after twisting or dipping.

Practically, it is difficult to control spinning conditions of quenching in the air-gap, washing, and drying of the fiber during spinning of the fiber with large denier in comparison with the spinning process of the fiber with small denier, so rarely securing desired physical properties of the fiber and scarcely maintaining uniformity of the filaments.

Accordingly, it is nearly impossible to produce the industrial fiber referring to physical properties of the fiber with 50 filaments.

However, this patent is disadvantageous in that elongation is a relatively high 15.4% and tenacity is at most 47.8 cN / tex, thus securing insufficient competitiveness of the fiber for use as a tire cord in terms of tenacity and productivity.

However, U.S. Pat. No. 4,255,300 does not disclose the fact that the tenacity of the fiber is improved because polyvinyl alcohol is added to cellulose.

However, this patent is disadvantageous in that the fiber has very poor tenacity to be used as an industrial filament or a tire cord.

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