JPS59116408A - Drawn molded article having creep resistance - Google Patents

Abstract

PURPOSE:A drawn molded article useful as a fishing net, etc., having improved creep resistance, obtained by extruding a crystalline ethylenic copolymer having double bonds in the molecule in a molten state, drawing it. CONSTITUTION:A crystalline ethylenic copolymer having >=1, preferably 3-15 double bonds based on 1,000 carbon atoms in the molecule obtained by polymerizing ethylene and a diolefin (e.g., 1,3-butadiene, etc.) or ethylene, an alpha- olefin (e.g., propylene, etc.) and the diolefin is extruded in a molten state, and drawn by one or multiple stage, to give the desired drawn molded article having creep resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stretch molded article with improved creep resistance. Conventionally, polyethylene stretch molded products have been widely used for ropes, fishing nets, etc., but when used for a long time, sagging and walnuts occur due to creep, which poses a problem. In addition, especially in the case of high-strength monofilaments that require high strength, their practical strength is significantly limited due to creep elongation.

Based on the above, the present inventors have conducted various studies to solve this problem, and as a result, a stretched molded product obtained from a crystalline ethylene copolymer containing double bonds in the molecule has the above problem. The inventors have discovered that this is effective in solving the problem, and have arrived at the present invention. That is, the present invention uses ethylene and diolefin or ethylene.

Obtained by melt extrusion and stretching of a crystalline ethylene copolymer containing one or more double bonds per 1000 carbon atoms in the molecule, which is a copolymer with other α-olefins and diolefins. It is a stretch molded product with improved creep resistance.

The crystalline ethylene copolymer referred to in the present invention is a copolymer of ethylene and diolefin, or a copolymer of ethylene, α-olefin, and diolefin. As a diolefin,
1,3-butadiene, 1,4-hexadiene, l,5-
Hexadiene, diclopentadiene, ethylidene-2-
Examples include norbornene, among which 1,3-butadiene is particularly preferred. Examples of the α-olefin include those having 3 to 20 carbon atoms, particularly preferably propylene, 1-butene, 1-1 hexene, or 1-4-methylpentene.

The copolymerization ratio of α-olefin is preferably 5 mol % or less, taking into consideration the decrease in strength due to the decrease in density.

The above copolymer needs to contain one double bond per 1000 carbon atoms in one molecule, particularly preferably from 3 to 15 double bonds/100 OC. If the number of double bonds is less than 1, a sufficient effect cannot be obtained, and if the number is too large, the density will decrease. Considering the formability or stretchability of the molded product and the strength of the obtained stretched molded product, the melt index is 0.1.
~2. og/lomm is preferred. Further, there is no particular restriction regarding the molecular weight distribution, but in order to improve the strength and stretch processability of the stretched product, HL]'1llI /M
It is desirable that I is 50 or less, that is, the molecular weight distribution is narrow.

The method for producing the above copolymer is not particularly limited; for example, it can be produced by a known polymerization method using a Ziegler catalyst, a Phillips catalyst, etc., which are widely used in the polymerization of ethylene. -13386
or Japanese Patent Application No. 57-106736.

The stretched product of the present invention is produced by a melt extrusion stretching method. That is, it is obtained by melt-extruding a crystalline ethylene-based copolymer and subjecting it to one-stage or multi-stage stretching. Extrusion conditions vary slightly depending on the melt index and ■I/MI value of the ethylene copolymer used, but usually,
Cylinder temperature 150~300℃ Die temperature 200~3
In the range of 30'C. In the present invention, lubricants, stabilizers, ultraviolet absorbers, pigments, fillers, etc. can be used as necessary.

According to the present invention, the creep resistance can be significantly improved without reducing the strength and elongation of conventional stretched thermoplastic resin molded products. Also, the rope that will be processed from now on,
The quality and durability of nets etc. can be greatly improved.

For example, ropes for fixed nets may suffer from long-term loads.
For applications where the rope itself is not allowed to stretch at a certain level of tension, conventional ropes have a long service life due to creep resistance, even if there are no problems with weather resistance or residual strength. However, by using the rope according to the present invention, the service life can be greatly extended.

Next, the present invention will be explained in more detail by giving Examples and Comparative Examples.

In Examples and Comparative Examples, monofilaments were molded under the following conditions.

Extruder: 40m1m9!6 Extrusion humidity: C, 160, C2250, C8290H29
0D290°C/z/l/; 1. On/m96X10n/mLX4,
oH air gap; 5 cm Cooling water tank temperature; 30°C Wet stretching method Stretching temperature; The physical properties of were measured by the following method.

1) MI, HLMI; JIS K67582
) Strength/elongation; JIS L 1073 grip interval 300 mm; take-up speed 300 min/m; temperature 20°C; 3) Creep resistance; load 29/Denichino L measurement time 8 hr; sample length 300 m/m 4) Double bond number measured by infrared absorption spectrum and C'''NMR Example 1 20 g of magnesium ethylate, 1 aluminum trichloride
．． A co-pulverized product obtained by co-pulverizing 66 g and diphenyljethoxysilane 272I using a vibrating ball mill and 88 g of titanium tetrachloride were reacted at 90°C in an n-hebutane solvent to obtain a solid catalyst component. .

Using 25 mq of this solid catalyst component and 07 mmol of triisobutylaluminum, 8 g of butadiene was charged in 70 ml of isofutane, and the hydrogen partial pressure was adjusted to 15 kg at 90°C.
/L:I? Polymerization was carried out at L (gauge pressure) ethylene partial pressure of 5 kg/d (gauge pressure) for 30 minutes. The resulting copolymer of ethylene and butadiene had a melt index of 05 and a number of double bonds of 5 per 1000 carbon strands. Table 2 shows the physical properties of the monofilament. Example 2~
5. In Comparative Examples 1 to 3 and Example 1, the ethylene copolymers shown in Table 1 were obtained by changing the type and amount of comonomer.

Table-1 Table 2 shows the physical properties of each monofilament.

Claims (1)

[Scope of Claims] ]) Copolymers of ethylene and diolefins, or copolymers of ethylene, other α-olefins, and diolefins, containing one or more double bonds per 1000 carbon atoms in the molecule. 2) Stretched product with improved creep resistance obtained by melt-extruding and stretching a crystalline ethylene-based copolymer having
14-hexadiene, 1,5-hexadiene, diclopentadiene, and ethylidene-2-norbornene. 3 to 15 per 1000 carbon atoms. Stretched product according to item 1 or item 2 4) The crystalline ethylene copolymer has a melt index of o, 1 to 2. og/lom= and see (IJ4I /M
Stretch molded product according to any one of claims 1 to 3, wherein I is 50 or less