JPS62280241A - Polyethylene resin composition - Google Patents

Abstract

PURPOSE:To obtain the title compsn. having excellent flame retardance, mechanical characteristics and low-temp. resistance to brittleness and producing no toxic gas when being burnt, comprising a specified linear low-density polyethylene (PE) and an inorg. metal hydroxide and/or an inorg. metal hydrate. CONSTITUTION:100pts.wt. in total of 20-70wt% linear low density PE contg. ethylene units and 0.2-20mol% alpha-olefin units whose carbon no. is 6 or more and melt index and density are 0.05-5.0g/10min and 0.900-0.930g/cm<3>, respectively, and 80-30wt% inorg. metal hydroxide [e.g. Mg(OH2)] and/or an inorg. metal hydrate (e.g. 2MgO.6SiO2.3H2O) are blended with 6 or less pts.wt. carbon black whose average particle size is 1-300mum, if necessary.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial application field] The present invention relates to a polyethylene resin composition.

More specifically, the present invention relates to a polyethylene resin composition that has excellent flame retardancy, does not generate toxic gas even if burned, and has excellent mechanical properties and low-temperature embrittlement resistance, and is suitable as a material for covering electric wires, for example.

[Prior Art and its Problems] Conventionally, in order to make thermoplastic resin flame retardant, a halogen compound has been added to the resin as a flame retardant. However, when a thermoplastic resin containing a halogenating agent is burned, it has the disadvantage that toxic gas is generated.

In order to overcome this drawback, it has been proposed to mix magnesium oxide and fine carbon powder with a thermoplastic resin (see Japanese Patent Publication No. 10898/1989).

Although the composition described in the above-mentioned publication has solved the above-mentioned drawbacks, since a large amount of inorganic filler is blended into the thermoplastic resin, the elongation of the composition is significantly reduced and the low-temperature embrittlement temperature is low. New problems have arisen, such as the rise in

[Object of the invention] The object of the invention is to provide a polyethylene resin composition that has excellent flame retardancy, does not generate toxic gas when burned, and has excellent tensile properties such as elongation and low-temperature embrittlement. It is to be.

Another object of the present invention is to provide a polyethylene resin composition that is excellent for use as a material for covering electric wires, for example.

[Means for achieving the above object] In order to achieve the above object, as a result of intensive research, this inventor selected a specific polyethylene resin as a thermoplastic resin and selected a specific compound as an inorganic filler. The inventors have discovered that the above object can be achieved by combining these, and have arrived at the present invention.

``In other words, the outline of this invention is that ethylene units and carbon 1
20 to 70% by weight of linear low-density polyethylene having &6 or more α-olefin units and a melt index of 0.05 to 5.0 g/lG min, and inorganic metal ice oxides and/or inorganic metals. Hydrate 80-3
This is a polyethylene resin composition characterized in that it contains 0% by weight.

The linear low density polyethylene (hereinafter abbreviated as LLDPE) has ethylene and carbon atoms of 6 or more, preferably 6 to 6.
10 α-olefins, such as hexene-1,4-methyl-pentene-1, octene-1, decene-1, etc.
- LLDPEs obtained by copolymerizing one or more olefins in an amount of 0.2 to 20 mol %, especially 1 to 10 mol % in the liquid phase or gas phase are preferable. Density is 0.900~0.940g
/ crrr', preferably 0.910 to 0.93
0 g/crrI′, and the melt index (
MI) from 0.05 to 5 g/10 min, preferably from 0.1 to
There is one with 3.0 g/10 minutes.

Here, the number of carbon atoms of the α-olefin in the LLDPE is 5.
If it is below, the tensile properties and low-temperature embrittlement of the polyethylene resin composition may deteriorate, which is not preferable.

In addition, when the content of α-olefin units having 6 or more carbon atoms in this LLDPE exceeds 20 mol%, the tensile strength
As the elastic modulus decreases, heat resistance may also decrease.
Moreover, if the content is less than 0.2 mol%, this α-
The effect of containing an olefin unit may not be apparent.

Also, the MI of this LLDPE is 0.05 g/10
If it is less than 5.0 g/710 minutes, the moldability of the polyethylene resin composition may deteriorate, and if it exceeds 5.0 g/710 minutes, tensile elongation and low-temperature embrittlement may deteriorate.

Examples of the inorganic ice oxide include magnesium oxide, aluminum oxide, calcium oxide, etc., and examples of the inorganic metal hydrate include 2Mg0.6Si02.3
H20, A AC203・9SiO-3H20, ai2 o
3-3H20, hydration power Atsium silicate, and the like.

In this invention, each of the inorganic ice oxide and magnesium ice oxide may be used alone or in combination, and furthermore, the inorganic ice oxide or inorganic metal hydrate to be used is: It may be used alone or in combination of two or more types.

Among the above, glacial magnesium oxide is preferred.

Further, the inorganic metal ice oxide and/or inorganic metal hydrate in this invention has an average particle size of 2.2 to 8.0.
It is desirable that the average particle size is within the range of 2.5 to 5.0 lm, especially within the range of 2.5 to 5.0 lm. This is because the properties and low-temperature embrittlement properties are further improved.

This polyethylene resin composition is made of the above-mentioned specific LLDPE.
and the inorganic metal ice oxide and/or inorganic metal hydrate in a specific ratio.

The blending ratio is 20 to 70% by weight, particularly 25 to 80% by weight of the LLDPE, and 80 to 30% by weight of the inorganic metal ice oxide and/or inorganic metal hydrate.
, especially from 75 to 40% by weight.

If the blending ratio of the LLOPE is less than 20% by weight and the blending ratio of the inorganic metal ice oxide and/or inorganic metal hydrate exceeds 80% by weight, the tensile elongation and low-temperature embrittlement of the polyethylene resin composition will deteriorate. worsens, and the LL
When the blending ratio of DPE exceeds 70% by weight and the blending ratio of the inorganic metal ice oxide and/or inorganic metal hydrate is less than 30% by weight.

The flame retardancy of the polyethylene resin composition deteriorates.

Further, it is preferable that this polyethylene resin composition contains carbon black as a third component, because when carbon black is blended, the flame retardance of this polyethylene resin composition can be further improved.

This carbon black includes furnace black,
Any material can be used, such as thermal black, acetylene black, Kettin black, etc. produced by the furnace method, channel black, naphthalene black, etc. produced by the impact method.

From the viewpoint of improved flame retardancy, workability, uniform crosstalk, etc., carbon black with an average particle size of 1 to 300 m, particularly 5 to 120 m, is preferred.

In this case, the blending amount of carbon black is as follows:
6 parts by weight or less of carbon black, preferably 6 parts by weight or less, particularly 2 to 4 parts by weight, per 100 parts by weight of the LDPE and the inorganic metal ice oxide and/or inorganic metal hydrate. If more than 1 part is added, not only will the opposite effect occur, but the elongation rate will also decrease.

Furthermore, this polyethylene resin composition may contain antioxidants such as hindered phenol-based, phosphorus-based (phosphite-based, phosphate-based, etc.) and amine-based antioxidants, for example, benzotriazole, as long as they do not impede the purpose of the present invention. A benzophenone-based ultraviolet absorber, an aliphatic carboxylic acid ester-based external lubricant, a paraffin-based external lubricant, a commonly used flame retardant, a mold release agent, an antistatic agent, a coloring agent, etc. can be added. Examples of the hindered phenolic antioxidant include BIT (2,8-di-tert-butyl-P-cresol) and "Irganox 1078J" manufactured by Ciba Geigy.
, "Irganox 10IOJ (all indicate trade names)", "Ethyl 330J (trade name) manufactured by Ethyl Co., Ltd.,""Sumilizer GMJ (trade name) manufactured by Sumitomo Chemical Co., Ltd.", etc. can be suitably used.

In addition, inorganic fillers, organic fillers, rubber-like elastic bodies, etc. can be blended as necessary.

Examples of the inorganic filler include carbonates such as calcium carbonate, magnesium carbonate, and dolomite, sulfates such as calcium sulfate and magnesium sulfate, sulfite groups such as calcium sulfite, talc, clay, mica, asbestos, glass fiber, and glass. peas, calcium silicate, montmorillonite, bentonite and other silicates, iron, zinc,
Examples include metal powders such as aluminum, ceramics such as silicon carbide and silicon athyl-7ide, their whiskers, carbon black, graphite, and carbon fibers. Mixtures of fillers can be used.

The inorganic filler may be in the form of particles, plates, or fibers, but preferably has a particle size in the range of 0.2 to 20 gm.

Examples of the rubbery elastic body include ethylene-propylene rubber, ethylene-propylene-nonconjugated diene rubber,
Ethylene-1-butene rubber, ethylene-isobutylene rubber, polyisobutylene, ethylene-isobutylene rubber,
Examples thereof include polybutadiene, styrene-butadiene rubber, acuti-2-dichlorobrobylene, MAS copolymer, MBS copolymer, MABS copolymer, and mixtures thereof. Among these rubber-like elastic bodies, ethylene-propylene rubber, ethylene-propylene-nonconjugated diene rubber, and the like are preferred.

This polyethylene resin composition can be produced, for example, by the following method.

In other words, ■ a method in which each component is tri-blended and then kneaded using a two-wheel mixer, ■ a method in which each component is added all at once to a Banbury mixer, etc., and kneaded, and ■ a masterbatch is made in advance and the remaining components are mixed. methods of kneading, etc.

This polyethylene resin composition has excellent flame retardancy and does not generate toxic gas when burned, so it is suitable as a material for covering electric wires such as communication cables and power lines.It also has excellent tensile properties and low-temperature embrittlement resistance. Therefore, it is suitable as a material for covering electric wires installed in cold regions. In addition, it can also be molded into various molded products such as sheets and films.

As the molding method, conventionally known methods such as extrusion molding, coextrusion molding, injection molding, air pressure molding, and mold molding can be employed.

[Effect of the invention] According to this invention, a specific linear low-density polyethylene and an inorganic metal ice oxide and/or an inorganic metal hydrate are blended in a specific ratio, so it has excellent flame retardancy. It also does not emit toxic gas even if burned, and has excellent tensile properties such as elongation and tensile strength, as well as low-temperature embrittlement.
A polyethylene resin composition suitable for a material for covering electric wires and the like can be provided.

[Example] (Examples 1 to 11, Comparative Examples 1 to 8) After preparing LLDPE, inorganic metal oxide, and carbon black, and triblending them in the proportions shown in Table 1,
The mixture was kneaded at 180°C to obtain pellets of the resin composition. Table 1 shows the results of tests using injection molded test pieces of this pellet.

Contents of each component> LLDPE A: MI = 1.0g/10 minutes,
Octene-1, unit content 4 mol% LLDPE B: M I = 2.5 octene-1
, unit content 8 mol% t, LDP! C: M I = 10 hexene-1,
Unit content 6 mol% LLDPE D: MI = 10.0, octene-1, unit content 2 mol% LDPE E: MI = 1.0, butene-1, unit content 4 mol% LLDPE F: MI =2.5, butene-1, unit content 6 mol% HOPE: High density polyethylene, M I = 1.0
LDPE: Low density polyethylene, MI=2.5M5-
A: Mg-B for Mg (OHh, average particle size 3.0)
: Mg(OH)2, average particle size 5.0 body Mg-G
: Mg(0)ri2. Average particle size 0. A-8 for B: A
Cross (OH) 3, average particle size 260 pieces Furnace: Furnace black, average particle size 20 meters pieces

Claims (1)

[Claims] (1) Contains an ethylene unit and an α-olefin unit having 6 or more carbon atoms, and has a melt index of 0.05 to
Linear low density polyethylene 20 which is 5.0g/10min
A polyethylene resin composition characterized in that it contains ~70% by weight and 80-30% by weight of an inorganic metal ice oxide and/or an inorganic metal hydrate.