JP2792234B2 - Polyethylene resin composition and extrusion coating material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyethylene resin composition having excellent mechanical properties and high-speed extrusion moldability, relates to a highly preferred extrusion coating materials to extrusion coating, such as a wire or cable.

[0002]

2. Description of the Related Art An electric wire is no longer useful if its insulation is lost due to deformation or tearing of its coating due to external pressure. However, the electric wire covering material is required to have high mechanical properties such as rigidity and tear strength.

Conventionally, as a method for improving the mechanical properties of an electric wire covering material made of a polyethylene resin, a method using a high-molecular-weight polyethylene resin (Japanese Patent Application Laid-Open No. 57-133136) or a linear A method using a polyethylene resin (JP-A-57-11747) and the like are known.

[0004]

However, the wire coating materials whose mechanical properties have been improved by these methods have the drawback that the fluidity is reduced and the extrudability is significantly deteriorated. Particularly in the case of extrusion coating molding or film molding of electric wires and cables, etc., in recent years, it has been required to be able to withstand molding at an extremely high speed, but a melt fracture is induced during molding due to a decrease in fluidity. For example, there is a problem that the surface smoothness is lost and the original mechanical properties cannot be obtained.

[0005]

Means for Solving the Problems The present inventors have made intensive studies on a method for overcoming such disadvantages, and as a result, have found that high-density polyethylene has low-flow linear low-density polyethylene and high-flow linear low-density polyethylene. By blending with high-density polyethylene, it maintains both the rigidity of high-density polyethylene and the mechanical strength of linear low-density polyethylene, and has excellent fluidity,
The present inventors have found that a polyethylene resin composition capable of high-speed extrusion coating of electric wires and cables can be obtained, and have accomplished the present invention.

That is, the present invention relates to a high-density polyethylene and a low-density polyethylene.
For polyethylene resin composition consisting of high density polyethylene
Oite, density of 0.94~0.965g / cm ^3, melt
High density polye with index of 0.1 ~ 2g / 10min
With styrene (A), the density is 0.915 to 0.935 g / cm ³
And the melt index is 0.2-2g / 10min
Flowable linear low density polyethylene (B ₁ ) and density
In 0.915~0.935g / cm ^3, a melt index
Flowable linear low-density polymer having a water content of 8 to 20 g / 10 min.
High-density polyethylene (A) consisting of styrene (B ₂ )
And low flow linear low density polyethylene (B ₁ ) and high flow
Weight with total of dynamic linear low density polyethylene (B ₂ )
Ratio (A) / {(B ₁ ) + (B ₂ )} is 1/6 to 3/2
Low flow linear low density polyethylene (B ₁ ) and high flow
Weight ratio of dynamic linear low density polyethylene (B ₂ )
(B ₁ ) / (B ₂ ) is 3/7 to 7/3.
To provide a polyethylene resin composition for extrusion coating .

[0007] As high-density polyethylene (A) used in the present invention, medium-pressure or with ethylene as a main component was prepared by low pressure polymerization processes, the density 0.9 4 ~
0.965 g / cm ³ of a homopolymer and a copolymer of ethylene, among which the melt index is 0.1.
Those in the range of 1 to 2 g / 10 min are preferred. Here, the density is a value measured according to JIS K-6760, and the melt index is a value measured at a temperature of 190 ° C. and a load of 2.16 kg according to JIS K-6760.

The linear low-density polyethylenes (B ₁ ) and (B ₂ ) are produced by a low-pressure polymerization method using ethylene and an α-olefin, and have a density of 0.915 to 0.935 g.
/ Cm ³ , and may have any stereotacticity of atactic, isotactic or syndiotactic. Examples of the α-olefin in the copolymer include α-olefins having 4 or more carbon atoms, such as butene-1, 4-methyl-pentene-1, hexene-1, and octene-1.

Low flow linear low density polyethylene (B
₁ ) The melt index is 0.2 to 4 g / 1
In general , those having a melt index of 0. 0 min are used because a composition having excellent mechanical properties can be obtained.
Those in the range of 2 to 2 g / 10 min are preferred.

The high flow linear low density polyethylene (B ₂ ) has a melt index of 8 to 20 g / g.
Normally used those 10Mi n but a melt index in that composition Of these flowability excellent good fast extrusion moldability is obtained preferably in a range of 10 to 20 g / 10min.

The amount of the high-density polyethylene (A) used depends on the high-density polyethylene (A), the low-flow linear low-density polyethylene (B ₁ ) and the high-flow linear low-density polyethylene (B ₂ ). Weight ratio to total (A) / ｛(B ₁ ) +
(B ₂ )｝ is usually in the range of 1/6 to 3/2 ,
Above all, the range of 3/7 to 5/5 is preferable from the viewpoint of obtaining a composition having excellent mechanical properties, particularly rigidity and high-speed extrusion moldability.

Further, linear low-density polyethylene (B ₁ )
The ratio of (B ₂ ) and (B ₂ ) is determined by their weight ratio (B ₁ ) / (B
₂ ) is usually in the range of 3/7 to 7/3, and especially 5/5 to 6.5 / 3.5 in that a composition having excellent mechanical properties and high-speed extrusion moldability can be obtained. A range is preferred.

Further, various additives can be added to the polyethylene resin composition and the extrusion coating material of the present invention as required. Representative examples of the additives are described below, but are not limited thereto, and various additives can be appropriately selected and used. (1) Modified resin: ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ultra-low density polyethylene (VLDPE), ethylene-propylene rubber (EPR), etc. (2) Organic flame retardants: chlorinated polyethylene, decabromodiphenyl oxide, tetrabromobisphenol A and derivatives thereof. (3) Inorganic flame retardant: antimony trioxide, aluminum hydroxide, magnesium hydroxide, zinc borate and the like. (4) Filler: alumina, kaolin, clay, calcium carbonate, talc, titanium oxide, silica and the like. (5) Colorant: inorganic pigment, organic pigment, dye, and the like. (6) Deterioration inhibitors: UV absorbers, antioxidants, metal deactivators, etc. (7) Stabilizers: lead stabilizers, zinc stabilizers, alkaline earth metal stabilizers, organotin stabilizers, etc. (8) Lubricants: paraffin, wax, fatty acid lubricant, silicone lubricant, stearamide amide lubricant, higher fatty acid metal salt lubricant, bisfatty amide lubricant, fatty amide lubricant, alkylamine lubricant, ester lubricant, Higher alcohol lubricants, etc. (9) Other additives: a dispersant, a copper damage inhibitor, a foaming agent, a plasticizer, a crosslinking agent, a crosslinking assistant, and the like.

The polyethylene resin composition and the extrusion coating material of the present invention can be prepared, for example, by mixing the above three components (A), (B ₁ ) and (B ₂ ) and, if necessary, additives with a usual kneading method, It is obtained by a method of kneading the above-mentioned various components using a kneader such as a single-screw extruder, a twin-screw extruder, a roll mill, a pressure kneader, and a Banbury mixer.

[0015]

Examples Examples, comparative examples and test examples are given below.
The present invention will be described in more detail, but the present invention is not limited thereby. The parts in the examples are on a weight basis.

The physical properties in each example were measured or evaluated by the following methods. (1) Melt index: Measured at a temperature of 190 ° C. and a load of 2.16 kg according to JIS K-6760.

(2) Tensile test: A sheet having a thickness of 1 mm was prepared from a sample by a pressing method and punched out with a No. 3 dumbbell of JIS K-6301 in accordance with the method according to JIS K-6760 (pulling speed 200 mm / min). The sample was subjected to a tensile tester to measure the breaking strength and the elongation at break.

(3) High-speed extrusion moldability: screw diameter 35
mm, a linear speed of 400 m / m using an extruder at a temperature of 200 ° C.
The sample was extrusion-coated on a core wire having a diameter of 0.4 mm to obtain an electric wire having an outer diameter of 0.76 mm, and the surface state of the obtained electric wire was evaluated visually and by palpation. The evaluation was 10 with the smooth good state being 10 and the worst rough state being 1.
It went in stages.

Examples 1-4 and Comparative Examples 1-6 Each component was dry-blended with the composition shown in Table 1 and then melt-kneaded at a temperature of 180 ° C. using a twin-screw extruder having a screw diameter of 30 mm and extruded. And pelletized. The physical properties of the obtained pellets were measured or evaluated by the above methods. Table 1 shows the results.

[0020]

[Table 1]

* 1) HDPE: high density polyethylene (MI: 0.8 g / 10 min, density: 0.95 g / cm ³ ). * 2) LLDPE-1: low-flow linear low-density polyethylene (MI: 1 g / 10 min, density: 0.92 g / cm ³ ). * 3) LLDPE-2: High-fluidity linear low-density polyethylene (MI: 10 g / 10 min, density: 0.91 g / cm ³ ). * 4) LLDPE-3: High-flow linear low-density polyethylene (MI: 18 g / 10 min, density: 0.92 g / cm ³ ). * 5) LDPE-1: low-flow high-pressure low-density polyethylene (MI: 0.25 g / 10 min, density: 0.924 g / cm ³ ). * 6) LDPE-2: High-flow high-pressure low-density polyethylene (MI: 2 g / 10 min, density: 0.922 g / cm ³ ). * 7) Modified resin: ultra-low density polyethylene (MI: 3.6 g / 10 min, density: 0.88 g / cm ³ ). * 8) Organic flame retardant: A combination of chlorinated polyethylene (chlorination ratio: 40%, density: 1.13 g / cm ³ ) and a tetrabromobisphenol A derivative in a weight ratio of 1/2.

[0022]

The polyethylene resin composition and the extruded coating material of the present invention have excellent mechanical properties such as tensile strength, hardness, rigidity and the like, and also have excellent fluidity, and especially excellent even at high shear. Shows fluidity. Therefore, at the time of extrusion molding,
In particular, high-speed extrusion molding (for example, in wire coating molding,
At a linear velocity of 400 m / min or more), a smooth, good molded product can be obtained without roughening of the surface, and it has excellent electrical insulation and adhesion to electric wires, and is very useful for covering electric wires. .

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08L 23/04 C08L 23/08

Claims (1)

(57) [Claims] 1. High density polyethylene and low density polyethylene
A polyethylene resin composition comprising a resin having a density of 0.94 to 0.965 g / cm ³ and a melt index
High-density polyethylene with a weight of 0.1 to 2g / 10min
(A) and a melt index having a density of 0.915 to 0.935 g / cm ³ .
Low flow linear low density with 0.2 ~ 2g / 10min
Polyethylene (B ₁ ) with a density of 0.915 to 0.935 g / cm ³ and a melt index
High fluidity linear low density with a weight of 8-20g / 10min
It becomes more polyethylene (B _2), and high density polyethylene (A), low flow linear low density po
Polyethylene (B ₁ ) and high flow linear low density polyethylene
Down the weight ratio of the sum of _{(B 2) (A) /} {(B 1) +
(B ₂ )｝ is 1/6 to 3/2, which is low flow linear low density polyethylene (B ₁ ) and high flow
Weight ratio (B ₁ ) of linear low density polyethylene (B ₂ ) /
(B ₂₎ extrusion, wherein the 3/7 to 7/3 der Rukoto
A polyethylene resin composition for coating .