KR890002110B1 - High strength polyethylene filament yarn's making method - Google Patents

Abstract

High density polyethylene chips having a melting rate of less than 0.9g/min and a fluorocarbon group copolymer are melt-mixed through a compounding machine having a twinscrew extruder to produce pellet chips, to which are added high density polyethylene chips and an antioxidant to be melt-drawn through a spinneret into a filament of high tenacity. The fluorocarbon group copolymer is composed of 1,1- difluoroethylene and hexafluoropropane to be added at the rate of 100-2000ppm to the total polyethylene. The filament has high tensility and good shrink resistance.

Description

Manufacturing method of high strength polyethylene filament yarn

The present invention relates to a method for producing a high strength polyethylene filament yarn.

Specifically, a fluorocarbon copolymer is added to a high-density polyethylene chip to make a pellet-shaped chip, and then mixed with a high-density polyethylene chip to which a fluorocarbon copolymer is not added, and melt-extruded in a filament form at an appropriate temperature range. By stretching at a high magnification, the present invention relates to a method for producing high-strength polyethylene filament yarn having excellent tensile strength and nodular strength shrinkage resistance compared to polyethylene filament yarn produced by a conventional method.

Most of the conventional polyethylene filament yarn was monofilament, and since the monofilament yarn has a lower specific gravity than other fiber materials such as nylon and polyester, it does not sink in water and has excellent hydrophobicity, flexibility, transparency, and toughness. Due to its superiority and low price compared to other organic fibers, it has been mainly used for fishing ropes, fishing nets and cords.

However, for the fiber used for such a purpose, the improvement of mechanical properties is recently requested | required, and especially in a fishing net etc., the improvement of tensile strength and crystal strength is urgently required. Accordingly, conventionally, filament yarn having a strength of 2-7 g / d is mainly obtained by melt extruding tens of thousands to hundreds of thousands of high-density polyethylene through an extruder, and then rapidly quenching it through a water tank directly under the nozzle and stretching it in one or multiple stages. In order to increase its strength, stretching was performed at a high draw ratio, or the extrusion temperature was increased to improve the uniformity and surface condition of the unstretched extrudate, which is the decisive cause of trimming during running of the yarn.

However, the main causes of lowering the homogeneity of the extrudate immediately after spinning are periodic or continuous melt fracture and Shark skin phenomena due to the viscoelastic intrinsic properties of high density polyethylene. The method of increasing the extrusion temperature cannot be a fundamental solution, but also has a problem of lowering the strength due to the cutting of the molecular chain due to the temperature rise. Particularly, when the hot polyma immediately after the melt extrusion is quenched in the tank directly under the nozzle, the poly Melt fracture phenomenon and sharkskin phenomenon tended to be more severe due to rapid contraction of the hemp.

On the other hand, in order to solve this problem, it is possible to select a polymer having a good fluidity, that is, a large melt index value, but this is not suitable for the production of high strength yarn because it is inversely related to the strength.

Also, the smaller the cross-sectional area of the extruded hole, that is, the extruded filament of sedenier, the more the melt fracture, the sharkskin shape, and the decrease in strength become significant. When the diameter of the extruded hole is 0.25 mm or less, the extrusion is performed. It was almost impossible. Fortunately, even if the thread is not trimmed at the time of stretching, this problem lowers the uniformity of each extrusion detention space, resulting in uneven stretching point between the single yarn filaments during hot stretching in the continuous process, making it difficult to stretch the entire filament at the same ratio without trimming. Therefore, high magnification stretching is also difficult.

On the other hand, when extruded into monofilament, it is possible to achieve high magnification and tensile strength can be satisfied. On the other hand, crystal strength is remarkably reduced, which has caused fatal defects when used for fishing nets.

Therefore, the present invention prevents cyclic or continuous melt fracture phenomenon and sharkskin phenomenon due to viscoelastic intrinsic properties during high-density polyethylene melt extrusion, and improves uniformity between spinning filaments and prevents elongation of elongation by stretching polyethylene. In order to obtain filament yarn, a suitable amount of fluorocarbon copolymer is added to a high density polyethylene chip to make a master badge, which is mixed with a high density polyethylene chip without fluorocarbon copolymer and added at an appropriate ratio, and an antioxidant is added in an extruder. Melt extrusion is carried out through a nitrogen atmosphere to cool, and the cooled unstretched yarn is wound in bobbins and stretched in 10,000 or more steps to produce polyethylene filament yarn having excellent tensile strength and nodule strength, no trimming and improved productivity. get There.

That is, the present invention will be described in more detail by melting a high density polyethylene chip having a melt index of 0.9 g / 10 min or less (as measured by ASTM-D 1238) and a fluorocarbon copolymer using a compounding machine having a twin screw extruder. Mix to make chips on the fillet.

, 방사구금공의 직경은 0.25-2.5mm

, 방사온도는 200-3550℃이다. 방사구금을 통해 방사된 필라멘트를 질소가스 분위기 또는 공기중에서 냉각시킨 다음 권취하며, 권취된 1가닥 또는 여러가닥의 필라멘트를 1단 또는 다단 연신을 행한다. 이때 연신온도는 128℃ 이하이며, 총 연신비는 7.0-25.0이 적당하다.In this case, the amount of the fluorocarbon-based copolymer is 1-5 wt% based on the high density polyethylene, and a copolymer of 1,1-difluoroethylene and hexafluoropropene is used. The fluorocarbon copolymer-containing high-density polyethylene chip and the fluorocarbon copolymer-containing high density polyethylene chip are mixed at an appropriate ratio, but the content of the fluorocarbon-based copolymer is high density polyethylene (containing fluorocarbon-based copolymer). 100-2000PPM, preferably 250-1000PPM, and 2,6-di-tert-butyl-4-methylphenol or n-octadecyl for high density polyethylene + high density polyethylene without fluorocarbon-based copolymer). -3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) -propionate, or 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol) , Or an oxidation inhibitor such as 4,4'-thio-bis- (3-methyl-6-tert-butylphenol) is added to 0.5 wt% or less with respect to the entire high density polyethylene, and then melt-extruded through an extruder and Quantified in the metering pump and through spinneret Radiate. The screw diameter of the extruder is 30mm

, The diameter of spinneret is 0.25-2.5mm

, Spinning temperature is 200-3550 ℃. The filament spun through the spinneret is cooled in a nitrogen gas atmosphere or in the air, and then wound up, and the single or multiple strands of the wound filament are stretched in a single or multistage manner. At this time, the stretching temperature is 128 ℃ or less, the total draw ratio is suitable 7.0-25.0.

As a result of continuous production of polyethylene filament yarn by the method according to the present invention, no trimming occurred, not only the surface uniformity of the filament was excellent, but also the tensile strength was 8.5g / d or more and the crystal strength was 4.0g / d or more. After prolonged immersion in room temperature water, there was no decrease in tensile strength and crystal strength, and it was found that dry heat and nonaqueous shrinkage were excellent.

Example 1-6

97.5 parts by weight of high-density polyethylene having a melt index of 0.8 g / 10 min and 2.5 parts by weight of copolymers of additives 1,1-difluoroethylene and hexafluoropropene were melt mixed in a compounding machine having a twin screw extruder Your chips.

Mix the chip and the high-density polyethylene chip containing no fluorocarbon copolymer, but mix so that the content of the fluorocarbon copolymer with respect to the entire polyethylene is as shown in Table 1, and as an antioxidant, 2,6-di After addition of -tert-butyl-4-methyl phenol (Table 1), the spinneret spins through a nozzle with 24 spinnerets, and then the multifilament cooled and solidified under a nitrogen atmosphere is wound at a speed of 450 m / min. The wound filament is stretched in three stages by passing four parts of the rollers driven at different speeds, and the stretching speed in the final stage is 760 m / min. The temperature of each stretching section is one stage (80 ° C) and two stages. (118 degreeC) and three steps (118 degreeC), and draw ratio is adjusted by the speed of a driving roller.

(See Table 1)

Tensile and Crystal Strength: Sample length 10cm, Tensile speed 1cm / min (using Instron)

Dry heat shrinkage: 100 ℃, 30min dry oven

Specific Shrinkage: 100 ℃ H ₂ O 30min

Claims (2)

A high-density polyethylene chip having a melt index of 0.9 g / min or less is added to the high-density polyethylene chip melt-mixed by adding a fluorocarbon copolymer to the high-density polyethylene chip without addition of the fluorocarbon copolymer and an antioxidant, followed by melt spinning. Method for producing a high strength polyethylene filament yarn, characterized in that. The method of claim 1 wherein the fluorocarbon-based copolymer is composed of 1.1-difluoroethylene and hexafluoropropene, characterized in that the addition of 100-2000PPM for the whole high density polyethylene.