JPH04296342A - Polyethylene resin composition and extrusion coating material - Google Patents

Abstract

PURPOSE:To provide a polyethylenic resin composition having excellent extrusion moldability and mechanical properties at ordinary or high temperature as well as mechanical properties at low temperature, and suitable for wire- coating, etc. CONSTITUTION:The objective composition is produced by compounding (A) a high-density polyethylene having a density of 0.945-0.955g/cm<3>, (B) a low- density polyethylene having a density of 0.915-0.935g/cm<3> and (C) an ultralow density polyethylene having a density of 0.875-0.905 at weight ratios (A/B/C) of (13-43)/(47-80)/(7-17). Preferably, the component B is a mixture of a low- fluidity straight-chain low-density polyethylene having a melt index of 0.2-2g/10min and a high-fluidity straight-chain low-density polyethylene having a melt index of 8-20g/10min and the component C is a mixture of a low-fluidity ultralow density polyethylene having a melt index of 0.2-2g/10min and a high- fluidity ultralow density polyethylene having a melt index of 3-10g/10min.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a polyethylene resin composition that has good extrusion moldability and mechanical properties at room temperature or high temperature, and also has excellent mechanical properties at low temperature, and extrusion coating for electric wires, cables, etc. The present invention relates to extrusion coating materials that are extremely suitable for.

0002

[Prior Art] Electric wires are used in any part of the world where humans live, and if their insulation is lost due to external pressure deforming their sheathing or tearing and damaging them, they become useless. It disappears. However, the wire coating material is -30℃
Mechanical properties such as flexibility and tensile elongation are often required even in the following low-temperature conditions.

By the way, conventional wire coating materials made of polyethylene resin include those made of high-density polyethylene, high-pressure low-density polyethylene, organic flame retardants, antimony trioxide, etc.; It had the disadvantage of poor mechanical properties. As a method for improving the mechanical properties at low temperatures, a method of adding an ethylene-vinyl acetate copolymer or an ethylene-ethyl acrylate copolymer is known.

0004

[Problem to be Solved by the Invention] However, it has been found that wire coating materials whose mechanical properties at low temperatures are improved (for example, by lowering the embrittlement temperature) using these methods deteriorate their mechanical properties at room temperatures. There was an issue.

[0005]Also, it is possible to use linear low density polyethylene instead of high pressure low density polyethylene, but if linear low density polyethylene and ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer are used, has poor compatibility and significantly deteriorates extrusion moldability, causing melt fractures and loss of surface smoothness during extrusion coating and film forming of electric wires and cables, etc.
Furthermore, there was a problem in that the mechanical properties at room temperature also deteriorated.

[0006]

[Means for Solving the Problem] As a result of intensive research into methods for overcoming these problems, the present inventors have found that high-density polyethylene such as high-pressure low-density polyethylene, linear low-density polyethylene, etc. By blending density polyethylene and ultra-low density polyethylene, it is possible to obtain a polyethylene resin composition that has good extrusion moldability and mechanical properties at room temperature, and also has excellent mechanical properties at low temperatures;
They have also discovered that this composition is extremely suitable as an extrusion coating material for electric wires, cables, etc., and have completed the present invention.

That is, the present invention provides high-density polyethylene (A
), low-density polyethylene (B), and ultra-low-density polyethylene (C), and a material for extrusion coating comprising this composition. It is something to do.

[0008] The high-density polyethylene (A) used in the present invention is, for example, a polyethylene with a density of 0.9 produced by a medium- or low-pressure polymerization method using ethylene as a main component.
35-0.965g/cm3, preferably density 0.9
Examples include homopolymers and copolymers of ethylene having a weight of 45 to 0.955 g/cm3, and those having a melt index (hereinafter abbreviated as MI) of 0.1 to 2 g/10 min are preferred. Here, the density is JIS
The value is measured according to K-6760, and MI is JIS
Temperature 190℃, load 2.16 according to K-6760
The value is measured in kg.

Examples of the low-density polyethylene (B) include high-pressure low-density polyethylene and linear low-density polyethylene. Among them, it is manufactured by low pressure polymerization method using ethylene and α-olefin, and has a density of 0.9.
Linear low-density polyethylene with a density of 15 g/cm3 or more and less than 0.935 g/cm3 is preferable because it has excellent mechanical strength, and these have any stereoregularity of atactic, isotactic, or syndiotactic. Good too. Examples of the α-olefin in the linear low density polyethylene include α-olefins having 4 or more carbon atoms, such as butene-1, 4-methyl-pentene-1, hexene-1, octene-1, etc. .

[0010] Furthermore, as the low-density polyethylene (B), when low-flow linear low-density polyethylene (B1) and high-flow linear low-density polyethylene (B2) are used in combination, the low-flow linear low-density polyethylene (B2) has excellent fluidity. This is preferable because it facilitates high-speed extrusion coating of electric wires, cables, etc.

[0011] As the low-flow linear low-density polyethylene (B1), one having an MI of 4 g/10 min or less is usually used. .2 to 2 g/10 min is preferable.

High fluidity linear low density polyethylene (B2
), those with an MI of 6 g/10 min or more are usually used, but in particular, those with an MI of 8 to 20 g/10 min are used because they provide a composition with good fluidity and excellent high-speed extrusion moldability.
Preferably, it is in the range of in.

As the ultra-low density polyethylene (C), any polyethylene having a lower density than the above-mentioned low density polyethylene (B) can be used, for example, a density of 0.875 g/cm.
Examples include low-density polyethylene having a density of 3 or more and less than 0.915 g/cm3. Among them, the density is 0.875 to 0.905 g because it provides a composition with excellent mechanical strength at low temperatures.
/cm3 low density polyethylene is preferred.

[0014] Furthermore, as the above-mentioned ultra-low density polyethylene (C), when a combination of low-fluidity ultra-low-density polyethylene (C1) and high-fluidity ultra-low-density polyethylene (C2) is used, it has excellent fluidity and can be used for electric wires and cables. These ultra-low density polyethylenes (
It is particularly preferred to use linear low density polyethylene (B1) and highly fluid linear low density polyethylene (B2) together with C1) and (C2).

Here, low fluidity ultra-low density polyethylene (C
As for 1), those having an MI of 2 g/10 min or less are usually used, and those having an MI in the range of 0.2 to 2 g/10 min are particularly preferable in that a composition with excellent mechanical properties can be obtained.

[0016] As the highly fluid ultra-low density polyethylene (C2), one having an MI of 3 g/10 min or more is usually used. is preferably in the range of 3 to 10 g/10 min.

[0017] In the present invention, high density polyethylene (A)
and low density polyethylene (B) and ultra low density polyethylene (
The usage ratio of C) is the weight ratio (A)/(B)/(
C) is (10-45)/(40-80)/(5-20)
(However, the sum of A, B, and C is 100) is the normal range, and in particular, it is possible to obtain a composition with an excellent balance of mechanical properties at low temperatures and mechanical properties at room temperature. A range of (20 to 42)/(45 to 65)/(12 to 17) (where the sum of A, B, and C is 100) is preferable.

[0018] Furthermore, when low-flow linear low-density polyethylene (B1) and high-flow linear low-density polyethylene (B2) are used together as linear low-density polyethylene (B), the usage ratio is , their weight ratio (B1)/(B2
) is usually in the range of 3/7 to 7/3, and in particular, 4
A range of /6 to 6.5/3.5 is preferred.

[0019] Furthermore, when low-fluidity ultra-low-density polyethylene (C1) and high-fluidity ultra-low-density polyethylene (C2) are used together as ultra-low density polyethylene (C), the usage ratio is determined by their weight ratio ( C1 )/(C2 ) is 2
The range of /8 to 7/3 is normal, and in particular, 3/7 to 6/4 in that a composition with excellent high-speed extrusion moldability can be obtained.
It is preferable that the range is as follows.

[0020] Furthermore, various additives can be added in required amounts to the polyethylene resin composition and extrusion coating material of the present invention, if necessary. Representative examples of additives are described below, but the present invention is not limited thereto, and various additives can be appropriately selected and used. (1) Modified resin: ethylene-propylene rubber (
EPR), acrylic acid-modified polyethylene, maleic anhydride-modified polyethylene, etc. (2) Organic flame retardants: chlorinated polyethylene, decabromodiphenyl oxide, tetrabromobisphenol A and its derivatives, etc. (3) Inorganic flame retardants: antimony trioxide, aluminum hydroxide, magnesium hydroxide, zinc borate, etc. (4) Fillers: alumina, kaolin, clay,
Calcium carbonate, talc, titanium oxide, silica, etc. (5) Colorants: inorganic pigments, organic pigments, dyes, etc. (6) Deterioration inhibitors: ultraviolet absorbers, antioxidants, metal deactivators, etc. (7) Stabilizers: Lead-based stabilizers, zinc-based stabilizers, alkaline earth metal-based stabilizers, organotin-based stabilizers, etc. (8) Lubricants: paraffin, wax, fatty acid lubricant, silicone lubricant, stearic acid amide lubricant, higher fatty acid metal salt lubricant, bis fatty acid amide lubricant, fatty acid amide lubricant, alkylamine lubricant, ester lubricant, Higher alcohol-based lubricants, etc. (9) Other additives: dispersants, copper damage inhibitors, foaming agents, plasticizers, crosslinking agents, crosslinking aids, etc.

The polyethylene resin composition and extrusion coating material of the present invention can be used, for example, in the above (A), (B) and (C).
) and additives if necessary, by a normal kneading method,
That is, it can be obtained by kneading the various ingredients described above using a kneading machine such as a single-screw extruder, twin-screw extruder, roll mill, pressure kneader, or Banbury mixer.

[0022]

[Example] Examples, comparative examples, and test examples are listed below.
The present invention will be explained in more detail, but the present invention is not limited thereto. Note that parts in the examples are based on weight.

Further, the physical properties in each example were measured or evaluated by the following methods. (1) MI: Temperature 19 according to JIS K-6760
Measurement was performed at 0° C. and a load of 2.16 kg.

(2) Tensile test: A 1 mm thick sheet was made from the sample using a press method, and the sheet was punched into a No. 3 dumbbell according to JIS K-6301. The sheet was tested according to the method according to JIS K-6760 (tensile speed 200 mm/min). It was applied to a tensile tester and the breaking strength and elongation at break were measured.

(3) Low-temperature embrittlement temperature test: A 2 mm thick sheet was prepared from the sample by pressing method, and JIS K-72
A test was conducted with the number of samples n = 3 according to the method according to No. 16, and 3
The lowest temperature at which no individual pieces were destroyed was measured.

(4) High-speed extrusion moldability: screw diameter 35
mm, using an extruder at a temperature of 200°C, linear speed 400m/m
A core wire with a diameter of 0.4 mm was extruded and coated with a sample to obtain an electric wire with an outer diameter of 0.76 mm, and the surface condition of the obtained electric wire was evaluated by visual inspection and palpation. The rating was 10 for the smooth and good condition and 1 for the worst rough condition.
I divided it into stages.

Examples 1 to 6 and Comparative Examples 1 to 2 After dry-blending each component with the composition shown in Table 1, it was melt-kneaded and extruded at a temperature of 180°C using a twin-screw extruder with a screw diameter of 30 mm. , pelletized. The physical properties of the obtained pellets were measured or evaluated by the above method. The results are shown in Table 1.

[0028]

[Table 1]

*1) HDPE: High density polyethylene (MI: 0.8g/10min, density: 0.
95g/cm3). *2) LLDPE-1: Low fluidity linear low density polyethylene (MI: 1g/10min, density: 0.92g/
cm3). *3) LLDPE-2: Highly fluid linear low density polyethylene (MI: 18g/10min, density: 0.92g
/cm3). *4) EEA: Ethylene-ethyl acrylate copolymer (MI: 6g/10min, density:
0.93g/cm3). *5) EVA: Ethylene-vinyl acetate copolymer (MI: 6g/10min, density: 0.95
g/cm3). *6) VLDPE-1: Low fluidity ultra-low density polyethylene (MI: 0.4g/10min, density: 0.90g/
cm3). *7) VLDPE-2: Highly fluid ultra-low density polyethylene (MI: 3.6g/10min, density: 0.88g/
cm3). *8) Organic flame retardant: A combination of chlorinated polyethylene (chlorination rate: 40%, density: 1.13 g/cm3) and tetrabromobisphenol A derivative at a weight ratio of 1/2.

[0030]

Effects of the Invention The polyethylene resin composition and extrusion coating material of the present invention have good extrusion moldability and mechanical properties at room temperature or high temperature, and are also excellent in mechanical properties at low temperature. In addition, as low-density polyethylene, low-fluidity linear low-density polyethylene and high-fluidity linear low-density polyethylene are combined, or as ultra-low-density polyethylene, low-fluidity ultra-low-density polyethylene and high-fluidity ultra-low-density polyethylene are used together. Those that are used in combination with low-density polyethylene exhibit excellent fluidity even under high shear, and can be used in extrusion molding, especially at high speed extrusion molding (e.g., wire coating molding at a line speed of 400 m).
/min), a smooth molded product with no roughening of the surface can be obtained, and it has excellent electrical insulation properties and adhesion to electric wires, and is very useful as a coating for electric wires.

Claims (9)

[Claims] 1. A polyethylene resin composition comprising high density polyethylene (A), low density polyethylene (B) and very low density polyethylene (C). 2. The composition according to claim 1, wherein the low density polyethylene (B) is linear low density polyethylene. Claim 3: The density of the high-density polyethylene (A) is 0.
．． 945 to 0.955 g/cm3, the density of low density polyethylene (B) is 0.915 to 0.935 g/cm3
and the density of ultra-low density polyethylene (C) is 0.875
-0.905 g/cm3, and the low density polyethylene (B) is linear low density polyethylene.
Compositions as described. 4. The weight ratio (A)/(B)/(C) of high density polyethylene (A), low density polyethylene (B) and ultra low density polyethylene (C) is (13 to 43)/(47).
~80)/(7~17) (However, the sum of A, B, and C is 1
4. The composition according to claim 3, wherein the composition is 00). [Claim 5] Claim 3, wherein the low-density polyethylene (B) is a combination of a low-flow linear low-density polyethylene (B1) and a high-flow linear low-density polyethylene (B2). Compositions as described. [Claim 6] Low-flow linear low-density polyethylene (
B1) melt index is 0.2-2g/10m
in, and highly fluid linear low density polyethylene (B2
6. The composition according to claim 5, wherein the melt index of ) is 8 to 20 g/10 min. [Claim 7] The low-density polyethylene (B) is made of a combination of a low-flow linear low-density polyethylene (B1) and a high-flow linear low-density polyethylene (B2), and 4. The composition according to claim 3, wherein the low-density polyethylene (C) is a combination of low-fluidity ultra-low-density polyethylene (C1) and high-fluidity ultra-low-density polyethylene (C2). [Claim 8] Low-flow linear low-density polyethylene (
B1) melt index is 0.2-2g/10m
in, high fluidity linear low density polyethylene (B2) has a melt index of 8 to 20 g/10 min, low fluidity ultra low density polyethylene (C1) has a melt index of 0.2 to 2 g/10 min and high fluidity super The melt index of low density polyethylene (C2) is 3 to 10 g/
The composition according to claim 7, wherein the treatment time is 10 min. 9. A material for extrusion coating, characterized by comprising the composition according to any one of claims 1 to 8.