JP2828289B2 - Method for producing polypropylene drawn tape yarn - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a stretched polypropylene tape yarn having high strength, high elongation, low resistance to longitudinal tearing, small denier unevenness, and excellent resistance to woven deterioration. Regarding the production method, the present invention provides a drawn polypropylene tape yarn useful as a woven yarn for various packaging bags and carpet base materials.

[Conventional technology]

BACKGROUND ART Conventionally, polypropylene stretched tape yarns are woven, and are often used as packaging materials for rice-wheat bags, cement bags, flexible containers, etc., and as carpet base materials.

However, in the conventional polypropylene stretched tape yarn, in order to impart high strength, for example, a method of stretching at a high magnification using a relatively high-molecular-weight polypropylene is difficult because of the occurrence of troubles such as breakage in the stretching process. Not only does it cause a decrease, but the tape yarn itself easily tears longitudinally and has a low elongation, and the woven fabric with this tape yarn has a large woven deterioration property, and as a result, it does not lead to improvement in strength, In order to solve these problems at once, the present inventors first melt extruded a relatively high molecular weight polypropylene at a relatively low temperature, and then withdrawn at a high draft rate, low peripheral speed roll and high peripheral speed A method of performing roll stretching by a peripheral speed difference in multiple stages, and
A method was invented for inventing a method of raising the temperature of a high peripheral speed roll during roll stretching (Japanese Patent Application Laid-Open Nos. Sho 61-252134,
No. 258013, JP-A-62-45713), these methods also have high strength, high elongation and vertical tear resistance, but they are not satisfactory in resistance to woven deterioration and denier. A new problem of unevenness also occurred.

[Problems to be solved by the invention]

The present invention has been made to solve the above-mentioned unresolved problems in the prior art in the polypropylene stretched tape yarn, and therefore, the present invention has high strength, high elongation,
An object of the present invention is to provide a method for producing a drawn polypropylene tape yarn which is less likely to be vertically split, has small denier unevenness, and has excellent resistance to woven fabric deterioration.

[Means for solving the problem]

The method for producing a polypropylene stretched tape yarn of the present invention is described in detail below.The polypropylene is melt-extruded onto a film, cooled and solidified to form a film, and then the film is cut into a tape, and a low peripheral speed roll is formed. In producing a polypropylene stretched tape yarn by stretching in the take-off direction while sliding on a heating curved plate provided between the high peripheral speed roll and the high peripheral speed roll, the melt flow rate of the polypropylene is 0.3 to 1.0 g / 10 minutes, and a curved body is provided preceding the heated curved plate, and the tape is slid on the peripheral surface of the curved body to fix the stretching start point on the peripheral surface. And

As the polypropylene used in the present invention,
A homopolymer of propylene is most preferred, but a copolymer of propylene with ethylene, butene-1, or the like, a mixture thereof, or the like may be used as long as the physical properties of the drawn tape yarn are not impaired. And the melt flow rate of this polypropylene is 0.3 to 1.0 g / 10 minutes, preferably 0.4
0.8 g / 10 min. If the melt flow rate is less than 0.3 g / 10 minutes, stretch breakage is likely to occur, and if the extrusion temperature is increased in order to prevent stretch breakage, strength, longitudinal tear resistance is reduced, and weaving deterioration resistance is also poor. On the other hand, if it exceeds 1.0 g / 10 minutes, the strength and the longitudinal tear resistance are inferior, and the fabric deterioration is inferior.

In the present invention, the polypropylene, if necessary, heat stabilizer, light stabilizer, lubricant, anti-blocking agent,
A flame retardant, an antibacterial agent, a pigment, and an inorganic filler and a dispersant thereof are added, melt-kneaded, melt-extruded into a film by a known method using a T-die, a circular die, etc., and cooled and solidified. Make a film.

The extrusion temperature at this time is preferably from 180 to 210 ° C, particularly preferably from 190 to 200 ° C. Extrusion temperature 18
If the temperature is less than 0 ° C, the extruded amount is reduced, and troubles such as breakage of stretching are likely to occur.On the other hand, if the temperature exceeds 210 ° C, the strength, the vertical tear resistance and the denier unevenness are small, and the excellent weaving deterioration resistance is excellent. This is because it is difficult to obtain a tape yarn.

Thereafter, the film is cut into a tape having a predetermined width, and the drawing direction is performed by sliding on a heating curved plate provided therebetween by a roll stretching method using a peripheral speed difference between a low peripheral speed roll and a high peripheral speed roll. And a relaxation heat treatment if necessary.

At this time, the temperature of the heating curved plate is preferably set to 100 to 140 ° C. If the temperature of the heated curved plate is less than 100 ° C., the stretching tension becomes large, and it becomes difficult to fix the stretching start point described later, and as a result, stretching breakage occurs or denier unevenness increases, while 140 ° C. Over, high strength,
This is because it is difficult to obtain a tape yarn having excellent resistance to woven fabric deterioration.

The stretching ratio at this time is preferably 4 to 6 times. If the draw ratio is less than 4 times, it is difficult to obtain a high-strength tape yarn, while if it exceeds 6 times, troubles such as stretch breakage are likely to occur, and the longitudinal tear resistance and the deterioration resistance to woven fabric are poor. This is because there is a tendency.

In the present invention, it is essential to provide a curved body in front of the heated curved plate, whereby the tape is slid on the peripheral surface of the curved body to set the stretching start point on the peripheral surface. It is fixed to. Therefore, this curved body has a convex cross section in the tape take-off direction and does not rotate.

At this time, the temperature of the curved body is preferably 40 to 100 ° C, and particularly preferably 50 to 80 ° C. If the temperature of the curved body is lower than 40 ° C., troubles such as stretching breakage are likely to occur, while if it exceeds 100 ° C., it becomes difficult to fix the stretching start point.As a result, stretching breakage occurs and denier unevenness occurs. This is because they tend to be large.

Hereinafter, the stretching step in the present invention will be described with reference to the drawings.

In FIG. 1, 1 is a low peripheral speed roll, 4 is a high peripheral speed roll, and the unstretched tape 5 and the stretched tape yarn 6 passing therethrough are sufficiently brought into contact with the peripheral surface of the roll to prevent slipping or the like. Then, they are pressed by rubber rolls 1a, 4a and the like, respectively. Reference numeral 3 denotes a heating curved plate having a curved surface having a convex cross section on one side. Reference numeral 2 denotes a curved body provided before the heated curved plate 3, which has an elliptical cross section, is made of metal, has a surface matte finish, and is non-rotating. In addition, 2a and 2b are guide rolls. The shape, setting position, setting temperature, and the like of the curved body 2 are appropriately determined according to various properties such as a melt flow rate of the polypropylene used, an extrusion temperature, a film thickness, a tape width, a stretching temperature, and a stretching ratio. Selected.

In the present invention, the unstretched tape 5 is slid between the low peripheral speed roll 1 and the high peripheral speed roll 43 on the heating curved plate 3 provided therebetween (in the direction of arrow in FIG. 1). In the production of the stretched tape yarn 6 by stretching in (1), the stretching start point is fixed on the circumferential surface by sliding on the circumferential surface of the curved body 2.

[Action and effect]

The method for producing a stretched polypropylene tape yarn of the present invention has the above structure, uses polypropylene having a melt flow rate in a specific range, and provides a curved body to fix the stretching start point on its peripheral surface, so that high strength is obtained. In addition, it is possible to stably produce a drawn polypropylene tape yarn having a high elongation, a resistance to longitudinal tearing, a small denier unevenness, and an excellent resistance to woven fabric deterioration, without causing forming troubles such as drawing breakage.

〔Example〕

Examples 1 to 6 and Comparative Examples 1 to 4 A propylene homopolymer was T
After being melt-extruded into a film with a die, cooled and solidified into a film while taking it at a speed of 12 m / min, the film is cut into a tape, and between a low peripheral speed roll and a high peripheral speed roll. By taking the stretching process shown in FIG. 1, the starting point of stretching is fixed on the peripheral surface of the curved surface by sliding on the peripheral surface of the curved surface, and the film is stretched in the take-off direction while sliding on the heated curved plate. After that, a 7% relaxation heat treatment was performed at 140 ° C. to produce a 1500 denier polypropylene stretched tape yarn. At this time, the melt flow rate, extrusion temperature, curved body temperature, heated curved board temperature, and stretch ratio of polypropylene were as shown in the table.

The measurement results of the tensile strength, tensile elongation, longitudinal tear strength, and denier unevenness of the obtained polypropylene stretched tape yarn are shown in the table. The tensile strength and tensile elongation are
Measured according to JIS Z1533, the longitudinal tear strength is the average when a test piece with a 30 mm tear in the stretching direction from one end in the stretching direction was torn in a 180 degree direction at a speed of 200 mm / min over a length of 50 mm. Load (g) to test piece thickness (mm)
It is expressed by the value divided by. The denier unevenness was calculated by the following equation for 50 samples sampled at a length of 90 cm.

Furthermore, using the obtained stretched tape yarn, a warp and a weft are driven at a rate of 15 yarns / inch with a sulzer type loom to form a plain woven fabric, and the tensile strength and the woven fabric deterioration rate of the woven fabric are measured. The results are shown in the table. The tensile strength was measured according to JIS L1068, and the weaving deterioration rate was calculated by the following equation.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a stretching step in the production method of the present invention. 1; low peripheral speed roll 2; curved body 3; heated curved plate 4; high peripheral speed roll 5; polypropylene tape 6; polypropylene drawn tape yarn

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-258013 (JP, A) JP-A-61-252134 (JP, A) JP-A-64-245715 (JP, A) JP-A-60-1985 239538 (JP, A) JP 42-8410 (JP, B1) JP 51-40175 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) D01F 6/04-6 / 06 D01D 5/42 D02J 1/22 301

Claims (1)

(57) [Claims] 1. A method in which a polypropylene is melt-extruded into a film, cooled and solidified to form a film, cut into a tape, and provided between a low peripheral speed roll and a high peripheral speed roll. In manufacturing a polypropylene stretched tape yarn by stretching in the take-off direction while sliding on a heated curved plate, the melt flow rate of the polypropylene is set to 0.3 to 1.0 g / 10 minutes, and the polypropylene is preceded by the heated curved plate. A method for producing a drawn polypropylene tape yarn, characterized in that a curved surface is provided, and the tape is slid on the peripheral surface of the curved surface to fix a stretching start point on the peripheral surface.