JPS58144113A - Production of polyethylene multifilament yarn for fish net - Google Patents

Abstract

PURPOSE:Polyethylene is melt extruded through a nozzle with a specific hole diameter, taken up at a specific draft ratio and drawn to produce a polyethylene multifilament yarn that is suitable for use in fish nets, because of its high knot strength. CONSTITUTION:Polyethylene is melt extruded through a spinneret with a plurality of nozzles of 0.4-1.1mm. hole diameter, taken up at a draft ratio of 1.1-6.0 (V1/V0 where V0 is extrusion speed and V1 is spinning speed) and the bundled yarn is drawn at a 7-12 draw ratio to give a multifilament yarn of less than 100 denier fineness. The resultant multifilament yarn is suitable for use in gill nets.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyethylene multifilament for fishing nets, and more specifically, to a method for producing polyethylene multifilament for fishing nets, and more specifically, the present invention relates to a method for manufacturing polyethylene multifilament for fishing nets, and more specifically, a polyethylene multifilament for fishing nets that has a fineness of 100 denier or less per filament yarn and has excellent knot strength. The present invention relates to a method for producing filaments.

The present invention will be explained below with reference to a gillnet in which the head of a fish is entangled in the mesh to catch it.

Conventionally, 880 denier (No. 4) or 1100 denier (No. 6) nylon monofilament has been used as thread for gillnets.This is because nylon is superior to goose material in terms of knot strength. This is because other conventionally known materials could not meet the knot strength required for gillnets.In other words, 880 denier nylon monofilament or 11OO denier monofilament was conventionally used for gillnets. It is fully patented as a gill net.

This is not because of its superior properties, but rather because it was unable to meet the knot strength required for gillnets made from other materials. Although it is true that gillnets made of nylon monofilament are generally accepted as extremely common and there are few questions about their characteristics, detailed research by the present inventors shows that It has become clear that gillnets made of nylon monofilament have the following drawbacks.

(1) Nylon has water absorption and adsorption properties, so it
If the net is used for more than a day, it will absorb dirt and become too conspicuous in the water, reducing the amount of fish caught. As a result, the effective area for fishing dormitories becomes smaller.

(3) For the same reason as (2), it is easy to come into contact with rocks on the ocean floor and is often damaged.

(4) The thread is thick, between 880 and 1100 deniers, and is difficult to entangle with fish.

(6) Due to the anti-tidal force of nylon, the entire net becomes bulky and narrow.
/A I'm tired of working on board the ship.

(6) Due to the hydrophilicity and water absorption properties of nylon, its strength in water decreases.

It is not easy to improve. For example (4
) can be overcome by using multifilament, which has the disadvantage that the monofilament is thick and does not easily entangle with fish. further increases, and the contact area between seawater and the filament also increases, resulting in a greater decrease in strength in water. Also, in order to overcome the disadvantages of (2) and (3), it is possible to use a float with a high buoyancy to force the net to stand up, but in this case, the entire net will be pulled and the fish will not be caught. The disadvantage is that the net becomes difficult to entangle upon contact.

Considering that gillnets made of nylon monofilament have the above-mentioned drawbacks, the inventor of the present invention proceeded with studies to realize an ideal gillnet. Polyethylene, which had been largely ignored due to its knot strength as a filament and other physical properties, focused on its superiority to nylon as a material itself, and conducted intensive research to create a polyethylene filament with superior knot strength. As a result, we have completed the present invention.

More specifically, the fineness of conventional polyethylene filaments is approximately 400 denier at the thinnest, and with this thickness, knot strength comparable to nylon cannot be obtained, and it is necessary to make it even thinner. The present invention has been completed based on this.

That is, in the present invention, 0Jfiφ~t per filament single yarn
A nozzle with a diameter of aswφ is not used, and the take-up speed v1 is set to 1.1<v1 for the ethylene resin discharge speed V.
Melt-spun in the range /'b < 6ρ, then stretched 7 to 12 times with the filaments interfering with each other,
A method for producing polyethylene multifilament for fishing nets, characterized in that the fineness per single filament is 100 denier or less.0 A method for producing polyethylene filaments having a thickness of 400 denier or less, especially 200 denier or less, per single filament. It is said that it is difficult to manufacture polyethylene filaments with excellent knot strength by reducing the fineness to 100 deniers or less as in the present invention. The aim is to find conditions for producing ethylene multifilament as long as it has excellent physical properties, especially knot strength, as a filament for use. Figure 1 shows the fiber thickness (denier)
As shown in the relationship between and knot strength, it has become clear that in the case of polyethylene filaments, the knot strength is significantly improved when the fiber thickness becomes too denier or less.

Generally, Nigiri ethylene filament is melt-spun from a spinning nozzle, cooled and taken out while being drafted, then stretched in a heated state, further annealed, and then wound up. However, polyethylene has poor draftability + (threadability) in the molten state, and thread breakage tends to occur during stretching, making it difficult to produce thin threads of 100 deniers or less. .

When manufacturing polyethylene filaments, the thickness of the filament is determined by the nozzle diameter and the draft ratio (vi/vo: v is the resin discharge speed from the nozzle, vl is the take-up speed) and the drawing ratio.

Therefore, if one wants to make a thin polyethylene filament having a denier of less than 100 denier, it is sufficient to determine these conditions, but among these conditions, the draw ratio has a great influence on the physical properties of the obtained polyethylene filament. FIG. 2 shows the relationship between stretching ratio and various physical properties. This is a comparison of the physical properties of a multifilament made of 10 single yarns of 66 deyres produced at different draw ratios, and the knot strength reached its maximum value near the draw ratio. It does not change much and reaches a maximum at a ratio of 9, which exceeds the limit, and rapidly decreases as the stretching ratio increases, and when the stretching ratio exceeds 9, it is no longer possible to obtain a practically sufficient hooking strength. On the other hand, the tensile strength increases rapidly as the stretching ratio increases, but a sufficient value cannot be obtained when the stretching ratio is 7 or less. In other words, when the stretching ratio is in the range of 7 to 12, all physical properties such as knot strength, hook strength, and tensile strength show practically sufficient values.

Therefore, among the factors that determine the thickness of the polyethylene filament, the stretching ratio is limited to 7 to 1 in the present invention. Fiber thickness (100 denier or less) and stretching ratio (7
-12) are determined, then spinning conditions such as nozzle diameter and draft ratio are determined. Draft ratio ('Vi/V
, ) can be obtained using the following formula.

Dn-Dr However, in the above formula, vl: Take-up speed (tx/5ea) L: Nozzle diameter (1) P: Melt density of resin (gd) = 0.73 Dn: Denier (d) Dr: Stretching ratio nozzle diameter Table 1 shows the draft ratio when various changes were made to the denier, denier, and stretching ratio. The ethylene resin used in this table is high-density polyethylene with a melt index of 0.45 and a melt density (p) of 0.73.
g shoulder.

Table 1 As is clear from Table 1, the draft ratio (V, /V・
) exceeds 6D, problems tend to occur during spinning, and when it exceeds around 6.7, spinning becomes difficult.◇On the other hand, when the draft ratio (V1/'V・) is ID, the spinning +) Since the ethylene resin meanderes in the cooling tank, it is necessary to maintain it at least 1.1 or higher.

Regarding the nozzle, if the diameter exceeds 1.1111Wφ, the draft ratio and stretching ratio must be increased.
Spinning breakage or drawing breakage occurs frequently, making spinning practically impossible, and when the oAM is less than 11φ, the number of spinning breakages increases. The shape of the nozzle opening is not limited to a circular shape, and may be an irregularly shaped nozzle, but it is necessary that the average diameter is within the above range. The spacing between the nozzles when spinning multifilament is not particularly limited, but if it is necessary to create a wafer shape in the subsequent drawing process, it may be determined taking that into consideration. It's good to do that. For example, in [interference shape 1], the filaments in a semi-molten state are brought into contact with each other by applying an external force or passing through a narrow gap immediately after the filaments are spun or threaded, and the filaments are lightly made semi-molten. Obtained by melt contact bonding. [In addition to using the method described above, interference shape 1 may also be obtained by actively providing a slit in the spinning nozzle, spinning a thin film connected to the filaments, and connecting the filaments with each other by this thin film.] . In addition, multifilament can be spun without any special means during spinning,
"Interference shape 1" is created by other means such as tightly bundling during the stretching process.
You can create it.

The polyethylene resin that has been melt-spun and then drafted under the conditions described above is further subjected to a stretching process. Stretching treatment essentially imparts various physical properties to the polyethylene filament, and as explained earlier with reference to FIG. The stretching ratio is limited to 7 to 1 times from the viewpoint of tensile strength and, more importantly, knot strength.

In the present invention, a specific nozzle diameter and a specific draft ratio are selected because it is necessary to obtain a thin filament with a single yarn denier of 100 denier or less and the drawing ratio is limited to 7 to 12 times. The stuttering ethylene resin that has been subjected to draft treatment is thinner than in the conventional case, and is prone to stretch breakage during the stretching process.

In general, stretch breakage occurs because the cross-sectional area of the stretched portion is extremely reduced compared to other parts, which is greater than the rate at which the strength of the stretched yarn increases due to molecular orientation accompanying stretching at the stretching temperature. It is a type of stress concentration. Therefore, in order to prevent this phenomenon, it is necessary to actively disperse stress. However, when looking at each single filament in a multifilament, it is difficult to disperse stress over the entire length of each single filament. Therefore, when stress is concentrated at one point in a single filament, it is necessary to disperse the stress to other filaments.

In the present invention, it is specified that the drawing is carried out with the filaments interfering with each other, which means that the stress during drawing is dispersed between the filaments. For this reason, as mentioned above, the saggi theory*si praise-
-# Partial contact bonding between single filament threads,
It is necessary to connect and bond the filaments together through a thin film. Alternatively, if such a means is not available during spinning, it is necessary to bundle a certain number or more of single filaments into a bundled yarn, and draw the yarn while dispersing stress by the frictional force between the filaments. If the drawing process is not performed with the filament single yarns interfering with each other to such an extent that such stress can be dispersed, drawing breakage will occur, making it practically difficult to manufacture filaments.

As described in detail above, the present invention has a structure in which a single filament is applied to a 0.
Using a nozzle with a diameter of 4II11φ to IJφ, the take-up speed v1 is
It is characterized by melt spinning C1 (Vl/￥・<6D) and then drawing it by 7 m with the filaments interfering with each other to make the fineness per filament 100 denier or less. In short, the conditions for industrially producing polyethylene multifilament, an unprecedented polyethylene multifilament of 100 denier or less, for obtaining the required knot strength as yarn for fishing nets, have been clarified for the first time. This is what I did.

Therefore, the present invention provides a yarn with excellent knot strength as raw yarn for fishing nets.
In addition to having the effect of industrially producing polyethylene multifilament of 0.00 denier or less, specifically without troubles such as spinning breakage or stretching breakage, the fishing net knitted from the raw yarn produced by the present invention has the following effects. It has the following advantages.

) Excellent in knot strength, hooking strength, and tensile strength.

←) Even if you leave it in the water for a long time, it does not stick to the net, so it does not absorb dirt, and the dirt will not make the net stand out and reduce the quality of your catch.

(c) Since the specific gravity is lighter than water, it stands up easily in water,
Effective fishing area is large. For example, the water depth is 913 m.

When the current was 11 to 2 Ω knots with respect to the net surface, ten polyethylene multifilaments of 66 denier obtained by the present invention were single-twisted at 100 T/m, and the mesh was 8011!
As shown in Figure 3 (&), the rise of the gillnet made with MSW knots between size 100 and 4 was 64 m with a float of -24 g/m% and a sink of 126 g/a; A gill net made in the same manner using six nylon multifilaments (denier) had a rise of 4.7 m under the same conditions, as shown in FIG. 3(b). Therefore, in terms of area ratio, the yarn using the yarn according to the present invention showed a larger value than the conventional product by 36%.

(2) For the same reason as mentioned in the previous section, the net does not lie on the seabed, so there is less damage caused by rocks on the seabed.

←) Because of the thin filament of less than 100 denier, it entangles well with fish and once caught, the fish will not escape.

(F) It has less rebound force than nylon, so it is not bulky and can be used smoothly when casting or hauling nets.

(g) It does not absorb water and its strength does not decrease in water. In other words, since the strength is the same when dry on land and when underwater or wet, it is possible to predict the need for repair and the risk of tearing.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between fiber thickness (denier) and knot strength, Figure 142 is a graph showing the relationship between stretching ratio and various physical properties, and Figure 3 (, ) is a graph showing the relationship between fiber thickness (denier) and knot strength. FIG. 8(b) is a side view showing how the used gillnet stands up in the sea; FIG. 8(b) is a side view showing how the conventional gillnet using nylon monofilament stands up in the sea. Patent applicant: Kosei Rayon Co., Ltd. Representative: Takeshi Hiroe

Claims (1)

[Claims] Q per filament single yarn, 4 ffφ~1. Discharge speed V of polyethylene resin using a nozzle having a diameter of L cod φ,
For, take-up speed v, l-1< VL/v, <
6J: A method for producing ethylene multifilament for fishing nets, which comprises melt spinning in the range of J and then forming a single filament.