JPH0214018A - Production of monifilament for twisted yarn - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention involves drawing a monofilament yarn having a core-sheath structure in which the core is a mixture of high-density polyethylene and polypropylene and the sheath is linear polyethylene. For some reason,
The present invention relates to a method for producing monofilament for twisting, which has high tensile strength and high knotting strength, has excellent abrasion resistance, and is suitable for use in ropes, fishing nets, and other applications that require knotting operations.

[Conventional technology]

Monofilaments of high-density polyethylene (hereinafter abbreviated as HDPE) are twisted or further knitted to take advantage of HDPE's excellent formability, mechanical strength, chemical resistance, water resistance, etc. It is widely used in ropes, fishing nets, and various nets.

However, in these applications, it has been pointed out that the knot strength is poor, especially when knotting operations are performed, and as a means of improving this, polypropylene (hereinafter referred to as P
It is abbreviated as P. ) has been proposed (see Japanese Patent Laid-Open No. 112023/1983).

On the other hand, in order to heat-seal and fix the weft and warp intersections in a fabric made of PP monofilaments, PP is used as the core, and HDP
A monofilament with a core-sheath structure in which a sheath is made of linear polyethylene (hereinafter abbreviated as LPE) such as E or linear low-density polyethylene is known (Japanese Patent Application Laid-Open No. 1983-1999).
(See Publication No. 21908).

[Problem to be solved by the invention]

It has been found that in the prior art method of improving the knot strength of HDPE monofilament by mixing PP, the knot strength is still insufficient and a new problem arises in that the abrasion resistance of the monofilament decreases.

Therefore, an object of the present invention is to provide a method for producing a monofilament for twisting, which has high tensile strength and high knot strength, and has excellent abrasion resistance.

[Means to solve the problem]

The method for producing a monofilament for twisting of the present invention has a melt index of 0.1 to 2.011710 minutes, a flow ratio of 10 or less (DPI 60 to 95% by weight),
Melt Flowray) 2>! It has a core-sheath structure in which the core is a mixture of 40 to 5% by weight of PP with a melt index of 0.2 to 10 g/10 min, and the sheath is LPE with a melt index of 0.311/10 min or more, and The method is characterized in that a monofilament yarn having a sheath cross-sectional area of 2 to 60 inches is extruded and then stretched at a stretching ratio of 5 to 12 times.

Note that the melt index (hereinafter abbreviated as MI) is defined as 190°C,
It was measured at a load of 2.16 klF, and the flow ratio (hereinafter abbreviated as FR) is the same as the above load of 2.1 klF.
2, 16 to MI at 6 kg 190 °C, ratio of MT 10 at load 10 to 9, MT1o
/Mr2.16, and the melt flow rate (hereinafter abbreviated as MFR) is the same (JTSK721
Measurements were made at 230°C and a load of 2.16 kg in accordance with the Standard.

In the present invention, H constituting the core of the monofilament
As DPK, the density is preferably 0,940 FI/
cm3 or more, ethylene homopolymers, copolymers of ethylene and up to 15% by weight of propylene, butene-1, etc., and the MI thereof is 0.1 to 2.0 g/10 min, preferably 0. It is selected from those with an FR of 10 or less, preferably 5 to 9 at 3 to 1.5 V for 10 minutes.

The MI of the HDPE core is 0.11! /10 minutes,
In extrusion molding of raw yarn, problems such as increased back pressure and generation of shark skin occur. Also, MI
exceeds 2.0g/10 minutes and FR exceeds 10,
In either case, tensile strength and knot strength are insufficient.

Examples of the PP constituting the core of the monofilament include propylene homopolymers, copolymers of propylene and up to 35% by weight of ethylene, butene-1, etc., and their MFR is 0.2 to 10g710. minutes, preferably 0
．． 5 to 8.011710 minutes.

If the MF'R of pp in the core is less than 0.2Ii/10 minutes,
As in the case of HD'PE, the problem of poor formability of the yarn arises, and on the other hand, 10 I! If the time exceeds 10 minutes, the tensile strength and knot strength will be insufficient.

The mixing ratio of HDPE and pp in the core is 60~60 for the former.
95 weights, preferably 60 to 90 weights, the latter being 40
If the mixing ratio is outside this range, the knot strength will be poor.

On the other hand, the LPE constituting the sheath portion of the monofilament includes so-called linear low density polyethylene, medium density polyethylene, high density I-lyethylene, etc. Among them, those having a density of 0g30&z~3 or more are preferable. Its Ml is 0
．． 3.9/10 minutes or more, preferably 0.5-10g/1
The HDPK that makes up the core is selected from 0 minutes.
It is preferable that the RItT is larger than the RItT of 6. The method for producing a monofilament for twisting of the present invention includes adding an antioxidant, an ultraviolet absorber, a lubricant, and an electrostatic charge to the HDPE and the PP that constitute the core, as necessary. Additives such as inhibitors and colorants are added and melt-kneaded at the above-mentioned mixing ratio using an extruder, Banbury mixer, Henschel mixer, etc. to form the core. The LPE added with the additive is used as a sheath, and the cross-sectional area of the sheath with respect to the total cross-sectional area is 2 to 60 mm, preferably 5 to 5 mm.
After extrusion-molding monofilament yarn having a core-sheath structure, which occupies 5 strands, it is stretched at a stretching ratio of 5 to 12 times, and heat-treated if necessary.

If the cross-sectional area of the sheath is less than 2 inches, no improvement in wear resistance will be observed, while if it exceeds 60 inches, the knot strength will be reduced.

Furthermore, if the stretching ratio is outside the above-mentioned range, the tensile strength or knot strength will be poor.

〔Example〕

Examples 1 to 3, Comparative Examples 1 to 9 One extruder equipped with a core-sheath type die extruded a mixture of HDPE and PP shown in the table that constitutes the core, and also constituted the sheath. The LPE shown in the table is fed from the other extruder to one extruder to extrude the monofilament yarn having the core-sheath structure shown in the table, and then stretched in heated water at about 100°C to a stretching ratio of 9.5 times. By doing so, a 400 d monofilament for twisting was produced.

Each monofilament obtained was evaluated for tensile strength, knot strength, and abrasion resistance, and the results are shown in the table.

In addition, the abrasion resistance was measured using 3,760 twisted yarns.
With one end fixed and a constant load applied to the other end, the fluff and standing condition were observed when sliding in contact with a rotating steel cylinder, and evaluated using the following rankings.

A: No fluff at all B: Partially fluffy C: There is fluff all over the surface. 〔Effect of the invention〕

Claims (1)

[Claims] High-density polyethylene 60-95 with a melt index of 0.1-2.0 g/10 minutes and a flow ratio of 10 or less
Weight% and melt flow rate of 0.2-10g/10
The core-sheath structure has a core made of a mixture of 40 to 5% by weight of polypropylene and a sheath made of linear polyethylene with a melt index of 0.3 g/10 minutes or more, and
After extruding monofilament yarn in which the cross-sectional area of the sheath portion occupies 2 to 60% of the total cross-sectional area, the stretching ratio is 5 to 1.
A method for producing a monofilament for twisting yarn, which is characterized by stretching it twice.