JPS59133238A - Ethylene/alpha-olefin copolymer composition - Google Patents

Abstract

PURPOSE:A resin composition suitable for use in wire-coating materials, prepared by mixing a specified ethylene/alpha-olefin copolymer with a high-pressure process low-density polyethylene. CONSTITUTION:The following components are mixed together: (A) 60-90wt% ethylene/4-10C alpha-olefin copolymer with a melt flow rate of 1-30g/10sec, ethylene content of 86-95mol%, density of 0.87-0.91g/cm<3>, crystallinity by X-ray method diffractometry of 5-25% and melting point by a differential scanning colorimeter of 60-100 deg.C, and (B) 40-10wt% high-pressure process low-density polyethylene with a melt flow rate of 0.1-100g/10sec and density of 0.91-0.925g/ cm<3>. The resin composition thus produced is excellent in stress cracking resistance, flexibility, weather resistance and aging resistance, as well as extrudability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ethylene/α-olefin copolymer composition. More specifically, the present invention relates to a resin composition mainly composed of an ethylene/α-olefin copolymer suitable as a wire coating material.

Various thermoplastic resins and elastomers such as butyl rubber and ethylene/propylene rubber are used as wire covering materials. Wire coating materials have flexibility, heat aging resistance,
It is required to have excellent electrical properties, mechanical strength, and weather resistance, as well as high melt tension and good extrusion texture for molding. In terms of electrical properties, polyolefin resins such as high-pressure low-density polyethylene, high-density polyethylene, and polypropylene, and polyolefin elastomers such as butyl rubber and ethylene-propylene rubber have excellent electrical properties. ), high-density polyethylene lacks flexibility, polypropylene has poor weather resistance, butyl rubber, ethylene-propylene rubber CNm strength color I.

All of the coating materials have their own drawbacks, such as poor mechanical strength unless carbon black is blended, and electrical properties deteriorate when carbon black is blended. Therefore, the present inventors have developed a method that has excellent ESCH and flexibility.
As a result of studies aimed at developing a resin composition for extrusion molding that has weather resistance, heat aging resistance, and excellent extrusion processability, we found that a specific ethylene/α-olefin copolymer and high-pressure low-density polyethylene were used. It has been found that the above object can be achieved by mixing, and the present invention has been achieved.

That is, the present invention provides a melt flow rate product (h+pR)
is 1 to 50g/10mln, ethylene content is 86
95 to 95 mo IV%, density 0.870 to 0.91
13 g 7cm3, X-ray crystallinity 5 to 2
5% and a melting point of 60 by differential scanning calorimetry (DsC).
Ethylene at 100°C to 100°C and α having 4 to 10 carbon atoms
- Copolymer (A) with olefin: 60 to 90% by weight and melt flow rate (MFR) of o, i to 10
0g/10+nin.

This invention provides an ethylene/α-olefin copolymer composition characterized by comprising 40 to 10% by weight of high-pressure low density polyethylene (B) with a density of 0.910 to 0.925 g/Cn13. be.

Ethylene/a-olefin copolymer (A
-) means MFP, (ASTM I) 1268, E)
is 1 to Og/IDm1n, preferably 1 to 2
0 g/10 m1n, ethylene content 86 to 95 mol%, preferably 87 to 94 mol%, density 0.8
70 to 0.910 g/an3, preferably 0.
880 to 0.9 D Og/C7n3, X-ray crystallinity of 5 to 25%, preferably 10 to 20
It is a random copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms and has a melting point of 60 to 100° C., preferably 60 to 90° C., as measured by % and DSC. M
If the FR is less than 1 g/10 min, the melt viscosity is high and molding is difficult, and if it is more than 60 g/10 m1n, the melt viscosity is low, the moldability is poor, and the mechanical strength is also low, which is not preferable. The ethylene content has a correlation with the density and crystallinity described below, but if it is less than 86 mol %, the mechanical strength is poor, and if it exceeds 95 mol %, it lacks flexibility and is poor in ESCH. Density is 0.870
If the weight is less than 7 cm3, the heat resistance and mechanical strength will be poor, and if it is more than 0.910 g/cm3, it will lack flexibility. Those with a crystallinity of less than 5% have poor mechanical strength;
Anything over 5% lacks flexibility. The melting point is ethylene.
It is a physical property value that represents the randomness of α-olefin 'I<M coalescence (t,).Those with a melting point of less than 60°C have poor heat resistance, and even if the density is within the range of the present invention, the melting point is 1 (30°C). '
Those exceeding C are copolymerized α-olefins in a block manner, and are inferior in mechanical strength and blocking resistance. The melting point in the present invention refers to the temperature increase rate 1 determined by DSC.
The temperature at the point showing a sharp endothermic peak determined from the endothermic curve at 0°C/m i 11 is 0. In addition, those with a molecular weight distribution (weight average molecular weight/number average molecule @) of 6 or less are further improved in mechanical strength. It is preferable because it is excellent. Further, those having a composition distribution σ of 2 or less are preferable because they further improve mechanical strength.
``The above molecular weight distribution is determined at 135°C after dissolving the ethylene/α-olefin copolymer (A) in 0-dichlorobenzene.
Gel permeation chromatography equipment (Gpe)
It is calculated by measuring the molecular weight distribution curve and then determining the weight average molecular weight and number average molecular weight. In addition, the composition distribution σ is obtained by completely dissolving the ethylene/α-olefin copolymer (A) in doxylene at 120°C, then lowering the temperature to room temperature, separating the p-xylene soluble part, and then Soxhlet extraction of the doxylene insoluble part. method, the extraction solvent was sequentially adjusted to n
-Hexane, benzene, n-hebutane, and p-xylene were used for extraction under the boiling point of each solvent, and each of the obtained extracts and p-xylene were used.
- The ethylene content of the xylene soluble portion and p-xylene unextracted material was measured and calculated using the following formula.

However, in the formula, X represents the ethylene content (mol %) of each fraction, M represents the average ethylene content (mol %) of the unfractionated copolymer, and Wi represents the weight fraction of each fraction.

Specifically, the α-olefin having 4 to 10 carbon atoms to be copolymerized with ethylene is 1-butene, 1-pentene, 1-
hexene, 4-methyl-1-pentene, 1-octene,
It is 1-decene, and is a mixture of one or more of these a-olefins. Copolymers with propylene are not preferred because they have poor mechanical strength.

The high-pressure low-density polyethylene (B) used in the present invention is a polyethylene with a large number of branches produced by so-called high-pressure radical polymerization, and has an MFT of 0.1 to 1 Do
g/10mln, preferably 0.5 to 80g/
10m1n, density 0.91 D to 0.925 g
/an3, and more preferably the swell ratio, which represents the degree of long chain branching, i.e., the internal diameter (Di 2.
Q mm, extrusion speed 10 m from a nozzle with a length of 15 mm
The ratio (Ds/D) of the diameter of the strand extruded at m/min (Ds) to the nozzle inner diameter (1) is 1.5 or more.

In addition, the high-pressure low-density polyethylene referred to in the present invention refers to copolymerized polyethylene with other polymerizable monomers such as α-olefin, vinyl acetate, and acrylic ester, as long as the purpose of the present invention is not impaired. It may be a combination.

The composition of the present invention comprises the ethylene/α-olefin copolymer (A): 60 to 90% by weight, preferably 70 to 80% by weight, and the high-pressure low density polyethylene (B):
It consists of 40 to 10% by weight, preferably 60 to 20% by weight. Copolymer (the amount of /J is 90%
If it exceeds 60% by weight, it has poor extrusion processability and fluidity, and if it has a low melt tension and is less than 60% by weight, it is E S CFf.

Less flexible. As a method for obtaining the composition, the ethylene/α-olefin copolymer (c) and the high-pressure low-density polyethylene (B) may be mixed in a predetermined range using various known methods, such as -blender, ribbon butt/under, Examples include a method of mixing with a Henschel mixer, a Tampura blender, etc., or a method of melt-kneading with an extruder, Nigu, Panburi mixer, etc. after mixing, and then pulverizing or granulating.

The composition of the present invention obtained by the above method preferably has a melt flow rate of 15 g/10 m1ntJ+W, and a composition having a melt flow rate of 15g/10m1n or more has a low melt tension and a stable shape of an extruded product. The improvement effect is small.

The composition of the present invention includes weathering stabilizers, heat stabilizers, antistatic agents, lubricants, pigments, dyes, inorganic or organic fillers,
Various additives, such as nucleating agents, plasticizers, and anti-aging agents, which are usually added to polyolefins, may be added to the extent that the purpose of the present invention is not impaired.

The composition of the present invention has excellent mechanical strength, flexibility, transparency, and ESol- (compared to conventional high-pressure processed low-density polyethylene, and also has excellent mechanical strength and flexibility compared to butyl rubber and EPDM. Since it has excellent heat aging resistance, weather resistance, and ozone resistance, it is suitable for use in tubes, pipes, etc., and especially for electric wires.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples in any way unless they go beyond the gist of the invention.

Example 1 Production of ethylene/1-butene copolymer> Ethylene/1-butene copolymerization reaction was carried out continuously using a +06 stainless steel polymerization vessel equipped with a stirring blade.

That is, hexane is continuously supplied as a polymerization solvent from the top of the polymerization vessel at a rate of 54/hour. 'Meanwhile, the polymerization liquid is continuously drawn out from the lower part of the polymerization vessel so that the polymerization liquid in the polymerization vessel is always 54%.

As a catalyst, (A) a reaction product of vanadium oxytrichloride and ethyl alcohol (prepared in a catalyst preparation container so that the molar ratio of vanadium oxytrichloride to ethyl alcohol was 1/1) was added in a polymerization vessel. so that the vanadium atomic concentration is 0.6 μIJ mol/l,
(D) Ethylaluminum sesquichloride ((CH)
A mixture 5 of Ancll, 5) and ethylaluminum dichloride [(CH)AlC12] (prepared so that the molar ratio of ethylaluminum sesquichloride and ethylaluminum dichloride was 7/6) was polymerized. Each was continuously fed into the polymerization vessel from the top of the vessel so that the concentration of aluminum atoms in the vessel was 4.8 mmol/β. Ethylene and 1-butene were fed from the top of the polymerization vessel at a rate of 650β and 0.7β per hour, respectively, and hydrogen gas was fed as a molecular weight regulator at a rate of 54 hours per hour.

The copolymerization reaction was carried out at 60° C. by circulating hot water through a jacket attached to the outside of the polymerization vessel. In this case, the pressure inside the polymerization vessel was 5.1 kq/crn2 (gujin).

When the copolymerization reaction is carried out under the conditions described above, an ethylene/1-butene copolymer can be obtained in a uniform solution state.

A small amount of methanol was added to the polymerization liquid taken out from the bottom of the polymerization vessel to stop the polymerization reaction, and the polymer was separated from the solvent by steam stripping treatment, and then dried under reduced pressure at 80°C overnight.

With the above operations, ethylene/1-butene copolymer (sample 1)
was obtained at a rate of 630 g/h.

The ethylene content of the copolymer measured by infrared absorption spectroscopy was 91.5 mol%, 1.4 F R3,3
g/10 min, density 0,889, crystallinity by χ ray 15z, melting point 66°C by DSC method, and molecular weight distribution (weight average molecular weight/number average molecular weight) 1.9.

Production and evaluation of the composition> 70% by weight of the copolymer obtained by the above method (sample 1) (
! l: High pressure low density polyethylene (Mirason FL6
0) and 30% by weight were blended in an extruder (extruder temperature 200°C, N2 sill).Then, the physical properties of the composition, copolymer (sample 1), and high-pressure low-density polyethylene were measured by the following method. .

Tensile strength at break (TB: k12/+J2): J IS
K 6301, but the test piece was a ring-shaped test piece with an inner diameter of J8 mm and an outer diameter of 2 Q mm.

Extrudability and extrusion texture: The composition was extruded using a capillary flow tester at 190°C, L/D = 45 mm/l, and a 5 mm nozzle, and the extrusion stress was 2.4 Omitted: The extrusion texture of the strand was evaluated using the gear pillar flow tester using the following five-grade scale.

1... No surface unevenness at all, good gloss 2... Almost no surface unevenness, no gloss 6... Slight surface unevenness, no gloss 4... Surface unevenness, no gloss 5 ...There are large irregularities on the surface and no gloss at all. Melt tension (g): Melt tension tester (manufactured by Toyo Seiki) at 150°C using a nozzle with L/D = 4 mm / 2.13 mm at one extrusion speed. It was determined under the conditions of 3 mm/min and a take-up speed of 20 rpm.

BSCR: Based on AST iD 1693, but the conditions are: Surfactant: Igepar 60% aqueous solution, Temperature: 50°
It was set as C.

1.8 parts by weight of dicumyl peroxide as a crosslinking agent and 0 parts by weight of Tsukurak MB (manufactured by Iriuchi Shinko Kagaku Kogyo Co., Ltd.) as an anti-aging agent for 100 parts by weight of heat aging-resistant composition 2.
．． 5 parts by weight and 0.5 parts by weight of Tsukrac 224 (manufactured by Irinai Shinko Kagaku Kogyo Co., Ltd.) were added and mixed and crosslinked at 175°C for 115 minutes.The crosslinked product was then left in air at 158°C for 7 days. The tensile strength at break and elongation at break before and after being left were measured according to JIS K 6301, and evaluated by the respective change rates ΔTB and ΔKB.In addition, Δ'rB,
ΔEB is the value of the strength at break 11j' and elongation at break after being left divided by the strength at break and elongation at break before being left, and is expressed in %.

The results are shown in Table 1. Tables 2 and 3 show the physical properties of the ethylene/α-olefin copolymer and high-pressure low-density polyethylene used in each Example and Comparative Example.

Examples 2 to 8 The same procedure as Example 1 was carried out except that the composition shown in Table 1 was used in place of the composition used in Example 1.

The results are shown in Table 1.

Comparative Examples 1 to 8 Comparative examples 1 to 8 were carried out in the same manner as in Example 1, except that the compositions shown in Table 1 were used in place of the compositions used in Example 1.

The results are shown in Table 1.

Claims (1)

[Claims] (1) Melt flow rate is 1 to 30g/1
0 min. Ethylene content lif& is 86 to 95 mol%, density is 0
．． 870 to 0.91087 cm, a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms (A ): 60 to 90% by weight, a melt flow rate of 0.1 to 100 g/10 m1n, and a density of 0.910 to 0.
925 g/(- high pressure low density polyethylene (B) =
An ethylene/α-olefin copolymer composition comprising 40 to 10% by weight.