KR910003065B1 - Manufacturing method of polypropilene yarn - Google Patents

Abstract

Polypropylene resin of melt index 6-15 is extruded in film form by extruder onto which a T-die or inflator is mounted. This extruded filmy resin is cutted into proper form, drawed in multi- stages, raised, heat treated and wound to form polypropylene fiber suited for optical cables or wire cloths. Specifically, multi- stage drawing is 3 stage and whole draw ratio is 6.0. In raising, needled cylindrical roller with needle density above 10 ea/cm2 is used. The raising process is carried out in overfeed or relaxed condition. Also heat is applied at 150 deg. C for 20 sec. The resulting polypropylene fiber satisfies the required properties of cables or wires which call for low elongation and heat shrimkage.

Description

Manufacturing method of polypropylene for optical cable or wire sheath

The present invention relates to a manufacturing method of polypropylene yarn for optical cable or wire coating.

In general, an optical cable or an electric wire is coated with a cushioning material around an optical fiber or a copper wire, and an outermost layer is coated with a synthetic resin. The polypropylene yarn, which is an object of the present invention, is used as a cushioning material or a coating material of an optical cable or an electric wire.

Polypropylene yarn is used for pile yarns such as rope yarns or dolls, and its use is extremely diverse. In recent years, polypropylene yarns are also widely used for carpet bubble paper instead of natural hemp.

However, rope and pile yarns are relatively demanding and can be produced simply by extruders consisting of T-die or blowing devices and slitting devices that cut films to a certain width.

However, the polypropylene yarn thus prepared has a high fineness of diamond-like fibrils expressed by the stretching effect, and the size of the formed diamond-shaped mesh is large, which is not suitable for use in optical cables or malleable coatings in addition to conventional applications.

The required properties of polypropylene used for cables or wires should not be high in elongation and heat shrinkage.

Elongation is to give resistance to dissociation and tension from reel during installation of optical cable, and thermal shrinkage is to give shape stability by preventing shrinkage against heat received during manufacturing process or final resin coating.

Therefore, the required properties of polypropylene for the optical cable or wire are less than 10% elongation, less than 4% of dry heat shrinkage, and more than 25kg of cutting strength. To maximize the buffering and coating effect, fibril fineness is required. It should be thin and the mesh size of diamond should be small.

This is because the greater the fineness of the fibrils, the higher the potential thermal contraction rate and the lower the coating capacity. Therefore, the inventors of the present invention have been able to devise the present invention as a result of intensive studies for producing an optical cable or a polypropylene yarn for wire coating which can satisfy the above required properties.

That is, in the present invention, the polypropylene resin having a melt index of 6-15 is extruded onto a film using an extruder equipped with a T-die or an inflation apparatus, cut into appropriate widths, multi-stretched, and brushed. The present invention relates to a method for producing an optical cable or a polypropylene fiber coating for electric wire coating, characterized by winding by heat treatment.

In the present invention, the multi-stage stretching process, which can be discussed in particular, can prevent whitening due to over-stretching of polypropylene, which can be caused by a conventional stretching method, and can maximize the stretching effect. There is an advantage that can form a finer mesh at the raising step of. In addition, the multi-stage stretching of the present invention refers to at least two or more stages and the three-stage stretching in the present invention, the fruit may be used for the hot water bath (hot water bath) or heat transfer or hot air circulation method.

However, the reason for employing the brushing process in the present invention is to improve the coverage of the polypropylene yarn for the optical fiber, and the fibrill forming the diamond-like mesh can be made finer to form microfibrils, thereby increasing the coating effect.

The method of raising is to use a needle-shaped or rolled cylinder-type roller and adjust the thickness and density of the needle according to the desired fineness and fibril level.

In general, the needle density is preferably at least 10 bones / cm 2, more preferably at least 50 bones / cm 2, and in order to improve workability and increase the raising effect, it is preferable to perform in an overfeed or relaxation state. The degree should be adjusted according to the melt index of polypropylene.

The melt index of the polypropylene is good in the range of 6-15, if the melt index is too high, the size of the mesh is large, on the contrary too low, there is a problem in the workability in the stretching and brushing process.

On the other hand, in the present invention, the annealing after raising is because the relatively high potential heat shrinkage due to the stretching effect of the stretching process and high elongation due to raising in the relaxed state can be reduced.

In addition, the thickness of the individual fibrils generated in the raising process of the present invention is finer, but less than 40μ (10D) is preferred, 20μ (5D) or less is more preferable.

The total fineness of the polypropylene yarn produced by the present invention is preferably at least 10,000 denier or more, more preferably 15,000 denier.

EXAMPLE

The polypropylene resin having a melt index of 10 was extruded at 205 ° C into a film at 143 g / min using an extruder equipped with an inflation apparatus, cut and cut into three stages (2.5 × 2.0 × 1.2) so that the total draw ratio was 6.0. And then brushed (110 immersion water / cm2 supercharge rate 11%) to form fibrills with 0.5-2.15 deniers, followed by heat treatment (150 ° C, 2.5 seconds), followed by winding at 79.5 m / min Polypropylene yarns were prepared.

Comparative Example 1

The same process as in Example 1 was omitted.

Comparative Example 2

The same process as in Example 1 was omitted.

Comparative Example 3

The same process as in Example 1 was performed, but the drawing, raising, and heat treatment were omitted.

Physical properties of the polypropylene yarn prepared in the above Examples and Comparative Examples are shown in Table 1.

TABLE 1

Claims (4)

An optical cable characterized in that the polypropylene resin having a melt index of 6-15 is extruded into a film using an extruder with a T-die or an inflation apparatus, cut into appropriate widths, multi-stretched and brushed, and then heat-treated and wound up. Manufacturing method of polypropylene company for electric wire coating. 2. The method of claim 1, wherein the multistage stretching is three stages of stretching, and the total draw ratio is 6.0. The method for manufacturing an optical cable or electric wire covering polypropylene yarn according to claim 1, wherein the raising is performed in a supercharged or relaxed state by using a needle-type cylinder-type roller having a needle density of 10 or more per square centimeter. The method of claim 1, wherein the heat treatment is performed at 150 ° C. for 20 seconds.