JPH0368126B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a filament, and more particularly, to a method for producing a filament that can produce a filament with good drawability, high strength, and excellent flexibility, creep resistance, abrasion resistance, and transparency. It is. Conventionally, filament resin compositions used for fishing nets, golf course nets, rockfall prevention nets, etc. have a density of 0.950 and are generally referred to as high-density polyethylene.
Ethylene copolymers (hereinafter referred to as high-density polyethylene) with a density of about g/cm ³ or more are often used. When flexibility is particularly required, an appropriate amount of high-pressure low-density polyethylene is blended with the above-mentioned high-density polyethylene. In the case of a resin composition for yarn for net making, unlike a resin composition for yarn for rope net making, strength is not required as much, but rather creep resistance, abrasion resistance, flexibility,
Various physical properties such as nodular strength and linear strength are required, and it is important that these physical properties are balanced.
However, high-density polyethylene is inferior in flexibility, abrasion resistance, linear strength, etc., and has not yet achieved satisfactory creep resistance. Therefore, various studies have been made on the melt index of the resin composition, the shape of the nozzle used when forming the yarn, the stretching temperature, etc. with a focus on the stretching ratio, but when the stretching ratio is set to a low ratio, Although the flexibility, abrasion resistance, and linear elongation are improved to some extent, the improvement is not significant, and on the contrary, the creep resistance is significantly deteriorated, so that satisfactory physical properties cannot be obtained. Furthermore, when low-density polyethylene is blended with high-density polyethylene, the flexibility is improved, but the strength and creep resistance are significantly reduced, and here too, it is not possible to obtain physical properties that are balanced and satisfactory with respect to the required properties. . As a result of intensive studies in view of the above circumstances, the present inventors have discovered a resin composition that has excellent flexibility, creep resistance, and abrasion resistance, and also has the necessary strength, and which has a good balance of these physical properties for use in filaments. , completed the invention. The filament resin composition used in the present invention is a linear polyethylene (hereinafter referred to as resin A) having a short chain branching with a density of 0.930 g/cm ³ or less and a melt index (hereinafter referred to as MI) of 0.2 to 10 g/10 min. ) 5 to 75% by weight and a density of 0.940 g/cm ³ or more,
It consists of 25 to 95% by weight of polyethylene (hereinafter referred to as resin B) with an MI of 0.1 to 10 g/10 min, and the MI of the resin composition is 0.2 to 2 g/10 min. Resin A used in the present invention is produced by using a Ziegler type catalyst consisting of a transition metal compound and an organometallic compound to produce ethylene, propylene, butene-1, hexene-1, 4-methylpentene-1, hexene-1, and hexene-1.
It is a resin mainly composed of ethylene, which can be obtained by copolymerizing α-olefins such as 1, octene-1, and decene-1. The polymerization method and conditions are not particularly limited, and it can be produced by any method such as a gas phase method, a slurry method, a liquid solution method, or a melt method. Further, the density of resin A used in the present invention needs to be 0.930 g/cm ³ or less. When the density exceeds 0.930 g/cm ³ , although a certain level of strength can be obtained, abrasion resistance, creep resistance, flexibility, etc. deteriorate, and various physical properties become unbalanced. In other words, a rapid improvement effect on abrasion resistance, creep resistance, and flexibility was observed at a density of 0.930 to 0.940 g/cm ³ , and this is an improvement effect that could never be predicted from high-density polyethylene. Density 0.910~0.925, especially from the viewpoint of creep resistance and flexibility
g/cm ³ is preferred. Furthermore, the MI of resin A used in the present invention (measured value when loaded with 2160 g at a temperature of 190°C) is 0.2 ~
It is necessary to be 10g/10min. This MI
When the amount is less than 0.2 g/10 min, the stretchability is significantly reduced, and only a low stretching ratio is possible, making it impossible to obtain the desired strength. Furthermore, if the MI exceeds 10 g/10 min, it becomes possible to stretch at a high magnification, but the achieved strength becomes low and it becomes impossible to maintain a balance with wear resistance, creep resistance, flexibility, etc. Resin B used in the present invention includes homopolymers as well as copolymers similar to those exemplified for resin A. In addition, the density of resin B used in the present invention is
It is necessary that it is 0.940 g/cm ³ or more. density
If it is less than 0.940 g/cm ³ , the linear strength of the filament in particular decreases, making it impossible to achieve the desired object of the present invention. Furthermore, the MI of resin B used in the present invention
(Measurement value when a load of 2160g is applied at a temperature of 190℃) is
It is necessary that it is 0.1-10g/10min. MI
If it is less than 0.1g/10min, the stretchability will be poor,
Netsuking is not stable, stretching breaks, and whitening of the filament occurs, making it impossible to obtain a high-quality filament.
Furthermore, if the MI exceeds 10 g/10 min, the elongation and knot strength will be insufficient. Regarding the mixing ratio of resin A and resin B in the resin composition used in the present invention, if there is too much resin B, that is, if there is too little resin A, the abrasion resistance, creep resistance, flexibility, etc. will be significantly deteriorated. Become. On the contrary, resin B
If the amount of resin A is too small, that is, if the amount of resin A is too large, the linear strength and knot strength will decrease. The mixing ratio of resin A and resin B is 5 to 75% by weight of resin A and 25 to 75% by weight of resin B.
95% by weight, preferably 50-90% by weight of resin B to 10-50% by weight of resin A. The MI (measured value when a load of 2160 g is applied at a temperature of 190° C.) of the resin composition needs to be 0.2 to 2 g/10 min. When the MI is less than 0.2 g/10 min, the drawability is significantly reduced, and the filament becomes cloudy and its transparency deteriorates. Also, MI
If it exceeds 2 g/10 min, there is no problem with both stretchability and transparency, but linear strength and knot strength are significantly reduced, and abrasion resistance and creep resistance are also extremely poor. Both resin A and resin B used in the present invention preferably have an HLMI/MI (JIS K6760) of 40 or less in order to further improve spinnability and stretchability in the present invention. In other words, this HLMI/MI is
When it exceeds 40, problems arise in terms of spinnability and stretchability, and the strength at the same magnification becomes weak.
When HLMI/MI is 40 or less, the spinnability and stretchability are good, and the strength at the same magnification is also high.
Stretching at a relatively low magnification is sufficient. An antioxidant is added to the filament resin composition used in the present invention in order to improve the antioxidative properties of the filament, and a metal soap is added in order to improve the extrudability from a nozzle. A specific example of the metal soap is calcium tearate. Specific examples of antioxidants include 2,6-ditertiary
Examples include butyl 4-methylphenol and suateryl thiodipropionate. Furthermore, the resin composition for filaments of the present invention may contain auxiliary components such as ultraviolet deterioration inhibitors, lubricants, and pigments, if necessary. Next, to further explain the method for producing a filament of the present invention, resin A and resin B are blended at a preferable mixing ratio, an antioxidant and a metal soap are added thereto, and the blend is extruded into a filament. After cooling, the filament is heated above 80℃ to 120℃.
It is stretched 6 times or more preferably 6 to 12 times in the following temperature range. Specifically, the above-mentioned blend is melted and extrusion molded into a monofilament to serve as a raw yarn at a shear rate of 400 to 1800 and a draft ratio of 1 to 5 using, for example, a round nozzle or an irregularly shaped nozzle. After cooling this unstretched monofilament with water,
Stretching is carried out at a temperature of 120°C at a stretching ratio of 6 times or more. In this case, the nozzle shear rate is
If it is less than 400, thread unevenness will occur in the filament, and unlike ropes that are formed by twisting hundreds or more filaments together, fishing nets, golf course nets, etc. Problems arise with raw yarn for things such as rockfall prevention nets. Further, when extruded at a shear rate of 1800 or more, there is a problem that the filament surface becomes rough and cannot be stretched. Resin A used in the present invention is much more susceptible to draft ratio than high-density polyethylene,
The set draft ratio is 1 or more, and the higher the draft ratio is, the higher the strength can be obtained as long as the drawability is not reduced. Preferably 1.5
A range of 4 to 4 is good. If the draft ratio is less than 1, troubles such as yarn wobbling will occur. In addition, the stretching temperature is preferably 80 to 120℃, preferably
The temperature is 90-100℃. Although stretching is possible to some extent even when the stretching temperature is 80° C. or lower, problems such as whitening occur during stretching, which significantly reduces strength, abrasion resistance, and creep resistance. Furthermore, the stretching ratio is 6 to 12 times, preferably 8 to 11 times.
When the stretching ratio is lower than 6 times, the stability of the netting point during stretching is poor, and not only is the stretching unstable, but the knot strength required for a general monofilament is low and the creep resistance is extremely poor. On the other hand, when the stretching ratio exceeds 12 times, many problems occur such as stretching breakage, whitening, abrasion resistance, elongation and knot strength reduction. Although the above is a case of a monofilament, even in the case of an aligned fiber formed by connecting several monofilaments, it is possible to manufacture the fiber by using the same molding conditions as above. When forming this aligned fiber, several nozzles connected through a slit are used, or several nozzles placed close together are used to obtain the extruded resin using a ballast effect, or the extruded resin is melted using a guide, etc. Conventionally known means, such as a method of partially adhering in a state, can be employed. The filament obtained by the method of the present invention has a linear strength of 4 to 8 g/d, a flexibility index of 5 to 15, a creep resistance of 20% or less, and an abrasion resistance of 300 or more, and has excellent flexibility, creep resistance, and abrasion resistance. It is a filament that has excellent properties, has the necessary strength, and has a good balance of these physical properties. By the way, it is generally said that reducing the density of the resin results in poor stretchability and a large decrease in strength, but it is true that high-pressure polyethylene and blended polyethylene of high-pressure polyethylene and medium-low pressure polyethylene have poor stretchability and are difficult to stretch. The maximum magnification is about 7 to 8 times. Moreover, the stretching method, especially the stretching temperature, must be fully considered.
Normally, stretching was not possible unless the temperature was about 80°C or lower.
Moreover, the strength was only about 2 to 4 g/d at most, which was not strong enough to withstand general filament used in fishing nets, golf course nets, rockfall prevention nets, etc., and it also had drawbacks in creep resistance and abrasion resistance. . However, the monofilament and fiber of the present invention have a linear strength of 4 to 8 as described above.
g/d, flexibility index 5 to 15, creep resistance 20% or less, abrasion resistance 300 or more, and has a good balance of physical properties as a general filament, making it suitable for general net making such as fishing nets, golf course nets, rockfall prevention nets, etc. It is most suitable as yarn for use. Although the monofilament according to the present invention is somewhat inferior in strength as a rope yarn, it has excellent flexibility, abrasion resistance, and creep resistance.
It can also be used as yarn for ropes that require these physical properties. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Examples 1 to 4 and Comparative Examples 1 to 3 Resins A-1 to A-4 and B-1 shown in Table 1,
C ₁ C ₂ C ₃ C ₄ AD 160 250 270 290 280 D ₁ D ₂ 270 270 (℃) 1.0 m/mφ, 150 hole nozzle using B-2 under the following conditions with an extruder of 75 m/mφ extrusion speed
Extrusion at 1100~1500sec ^-1 , air gap 60
After cooling with water, the film was placed in boiling water at 100° C. and wet-stretched at a stretching speed of 120 m/min. The fineness setting was 400De. In addition, resins A and B contain 2,6-di-tertiary butyl 4-methylphenol per 100 parts by weight of each resin.
0.1 part by weight of stearyl thiodipropionate 0.05 and calcium stearate 0.15 are added.

[Table] The results of each example are shown in the second table below along with the results of comparative examples.
Shown in the table.

【table】

[Table] Comparative Example 1 has sufficient linear and knot strength, but has a higher flexibility index than Examples 1 to 4.
Poor wear resistance and creep resistance. In Comparative Example 2, the density is almost the same as in Example 1, but the flexibility index is also high, and the abrasion resistance and creep resistance are also inferior. Also, the strength is low.

Claims (1)

[Claims] 1 Density 0.930g/ ^cm3 or less, melt index
5-75% by weight of linear low-density polyethylene with short chain branching of 0.2-10g/10min and density 0.940
g/ ^cm3 or more, melt index 0.1~10g/
The method is characterized in that a filament is obtained from a resin composition for a filament, which is made of a resin composition of 25 to 95% by weight of polyethylene and has a melt index of 0.2 to 2 g/10 min, mixed with an antioxidant and a metal soap. Method of manufacturing filament.