JPS61258013A - Production of polypropylene drawn tape yarn - Google Patents

Abstract

PURPOSE:To obtain the titled tape yarn having high strength and high elongation, slightly being teared longitudinally, by extruding polypropylene in a molten state, cooling and solidifying it to give a film, cutting it into tapes and drawing them under specific conditions. CONSTITUTION:Polypropylene is extruded into a film in a molten state by the use of an extruder, cooled and solidified while being taken up, to form a polypropylene film. Then, the polypropylene film is cut into tapes with a given width, the films are drawn in the take-up direction by roll drawing method as the first stage and drawn at <=1.5 draw ratio as the second and the following stages to give the aimed tape yarn.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a method for producing polypropylene stretched tape yarn that has high strength, high elongation, and is resistant to vertical tearing, and is suitable for use in various packaging bags and carpet base materials. The object of the present invention is to provide a polypropylene drawn tape yarn useful as a woven yarn, etc.

(b) Prior Art Conventionally, polypropylene drawn tape yarns have been woven and widely used as packaging materials such as rice and wheat bags, cement bags, flexible containers, etc., and as carpet base materials.

However, in conventional polypropylene drawn tape yarns, in order to impart high strength, the method of drawing to a high ratio using, for example, relatively high molecular weight polypropylene,
Not only does the occurrence of problems such as stretch breakage in the drawing process lead to a decrease in the quality of the fabric, but the tape yarn itself is prone to vertical tearing and has a low elongation of 11 [11], making the woven fabric made from this tape yarn difficult to form. However, in order to improve the longitudinal cracking properties, methods have been proposed to add calcium carbonate to polypropylene, rubber, ethylene propylene copolymer, etc. At present, longitudinal fissures are not sufficient to improve properties, and furthermore, there is a problem in that their addition causes a decrease in formability and strong electrical properties of the tape yarn.

(c) Problems to be Solved by the Invention The present invention has been made in view of the above-mentioned current situation. It is an object of the present invention to provide a manufacturing method that can be stably manufactured without causing troubles such as stretching breakage. (2) Means for solving the problems The method for manufacturing polypropylene stretched tape yarn of the present invention is described in detail below. Then, in producing polypropylene stretched tape yarn tm by melt extruding polypropylene into a film, cooling and solidifying it to form a polypropylene film, cutting the polypropylene film into tape shapes and stretching in the take-up direction, It is characterized in that the stretching is divided into two or more stages, and the stretching in the first stage is carried out by a roll stretching method, and the stretching in the second and subsequent stages is carried out at a stretching ratio of 1.5 times or less.

The polypropylene used in the present invention is most preferably a homopolymer of propylene, but copolymers of propylene and ethylene, butene-1, etc., and copolymers thereof may also be used as long as they do not impair the physical properties of the drawn tape yarn. It may also be a mixture of the following.

In addition, this polypropylene melt flow rate) a, 0
．． It is preferable that it is 3-2.5P/1G.

If the melt flow rate is less than 0.3P710 minutes, it will be difficult to increase the draw ratio and it will be difficult to stably produce a tape yarn having high tensile strength.

In addition, if the extrusion temperature is increased to increase the stretching ratio,
Elongation and longitudinal cracking cause a decrease in strength. On the other hand, 2.5P/
If the time exceeds 10 minutes, it becomes difficult to obtain a tape yarn that has high strength, high elongation, and is resistant to longitudinal tearing.

In the present invention, the polypropylene is added with a heat stabilizer, a light stabilizer, a lubricant, an antiblocking agent, a flame retardant, an antibacterial agent, a pigment, an inorganic filler, a dispersant thereof, etc. as necessary, A known method using a T-die, circular die, etc., preferably at 200 to 240°C.
It is melt-extruded into a film at a temperature of , and then cooled and solidified to form a polypropylene film. Here, the extrusion temperature is 200℃
If the temperature is less than 240°C, the extrusion rate will decrease and troubles such as drawing breakage will occur, resulting in cracking. On the other hand, if it exceeds 240°C, it will be difficult to obtain a tape yarn with high tensile strength, elongation, and longitudinal tear strength. .

In the present invention, when the polypropylene film is slit to a predetermined width to form a tape and stretched in the take-up direction, it is essential to carry out this stretching in two or more stages. With only one stage of stretching, it is not possible to stably produce a tape yarn that has high strength, high elongation, and is resistant to longitudinal tearing.

Furthermore, in the present invention, this two or more stages of stretching,
The first stage is a roll stretching method, and the second and subsequent stages are carried out at a stretching ratio of 1.5 times or less.

At this time, in the first step, a roll stretching method is used, the stretching temperature is preferably 110 to 140C, and the stretching ratio is preferably 3 to 140C.
After stretching, heat treatment is performed at a relaxation rate of 5 to 10 m as necessary.

Here, when using a hot plate stretching method, an oven stretching method, etc. other than the roll stretching method, the obtained tape yarn becomes easily creased, has low strength, and has low elongation. In addition, if the stretching temperature is less than 110°C or the stretching ratio exceeds 7 times, problems such as stretching breakage will occur and the quality will be poor, and the obtained tape yarn will tend to tear longitudinally and have a low elongation. easy. When the degree of stretching exceeds 140° C. and when the stretching ratio is less than 3 times, it becomes difficult to obtain a tape yarn with high strength.

In addition, from the second stage onwards, there are no particular restrictions on the stretching method.
The stretching temperature is preferably 120 to 150°C, the stretching ratio is 1.5 times or less as the total stretching ratio after the second stage, and after stretching, heat treatment is performed at a relaxation rate of 5 to 10 as required.

Here, if the stretching temperature is less than 120°C, troubles such as stretching breakage will easily occur; if it exceeds 150°C, it will be difficult to obtain a tape yarn with high strength.

If the stretching ratio exceeds 1.5 times, problems such as stretching breakage will occur, and the resulting tape yarn will have low longitudinal cracks, low strength, and low elongation.

(E) Functions and Effects Since the method for producing a stretched polypropylene tape yarn of the present invention has the above-described structure, a stretched polypropylene tape yarn that has high strength, high elongation, and is resistant to vertical tearing can be formed by stretching and tearing. It can be manufactured stably without any trouble.

(c) Example 1 - Example 1.2, Comparative Example 1.2 Propylene homopolymer (melt flow rate 0.5f
/10 minutes) in a die using a 65 w B extruder.
After melt-extruding into a film at 15°C and cooling and solidifying it while taking it off at a speed of 15 m/min to form a polypropylene film, the polypropylene film was cut into tapes and taken off at a temperature of 120°C using a roll stretching method. The first stage of stretching is carried out in the direction of
A 1200 denier polypropylene drawn tape yarn was produced by performing a second stage drawing at a temperature of 5°C and a 5th relaxation heat treatment at 145°C.

Note that the stretching ratio at this time was as shown in Table 1.

Table 1 shows the occurrence of stretching breaks during production, as well as the tensile strength, tensile elongation, and longitudinal tear strength of the obtained stretched polypropylene tape yarn.

The occurrence of stretching breakage was expressed by the number of yarn breaks when a total of 60 tape yarns were continuously produced for 3 hours. In addition, tensile strength and tensile elongation are JIS
Z1533 was used to measure the longitudinal crack strength.
It is expressed as the value obtained by dividing the average load (f) when tearing across the G temple by the test piece thickness -).

Example 3 A polypropylene drawn tape yarn was produced under the same conditions as in Example 2, except that the second stage drawing method was a hot plate method.

Comparative Example 3 A tape yarn was produced under the same conditions as in Example 2, except that the first stage drawing method was an oven method.

Comparative Example 4 A tape yarn was produced under the same conditions as in Example 2, except that the first stage drawing method was a hot plate method.

Comparative Example 5 A tape yarn was produced in the same manner as in Example 2, except that only one step of drawing was performed by the roll drawing method at a temperature of 145°C.

Comparative Example 6 A tape yarn was produced in the same manner as in Example 2, except that only one step of drawing was performed by hot plate drawing at a temperature of 145°C.

In addition, using the stretched tape yarns of Example 2.3 and Comparative Example 2.3, both the warp and weft were 12
A plain weave fabric was woven by driving at a rate of 100 mm/inch.

Table 2 shows the measurement results of the tensile strength and weaving rate of the obtained woven fabric.

Note that each of these physical properties was measured by the following method.

Table 2 according to tensile strength crab JIS L1068

Claims (1)

[Claims] In producing a polypropylene stretched tape yarn by melt extruding polypropylene into a film, cooling and solidifying it to form a polypropylene film, cutting the polypropylene film into tape shapes and stretching in the take-up direction, the stretching is performed by 2 times. Divided into more than one stage, and the first
A method for producing a polypropylene stretched tape yarn, characterized in that the stretching in the first stage is carried out by a roll stretching method, and the stretching in the second and subsequent stages is carried out at a stretching ratio of 1.5 times or less.