JPH05279578A - Intimate rubber-plastic mixture - Google Patents

Abstract

PURPOSE:To recycle rubber-plastic waste used for covering wires and cables, which waste has been hard to thermally dispose of in common combustion furnaces because of the high calorific value of the waste, and rubber-plastic waste overflowed from extruders in the course of production of wires and cables, by mixing a rubber-plastic waste resulting from the use thereof for wires and cables with unused rubbers and plastics to provide an intimate rubber- plastic mixture free of a practical problem with lowering of properties in comparison with the properties of unused rubbers and plastics not mixed with the rubber-plastic waste. CONSTITUTION:50-90wt.% unused rubbers and plastics are blended with 10-50wt.% powder of rubber-plastic waste having an average particle size of at most 100mum and resulting from the use thereof wires and cables.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a thermoplastic rubber / plastic and a rubber used for coating electric wires / cables.
It relates to a mixture of plastic with waste materials.

[0002]

2. Description of the Related Art In recent years, environmental pollution due to an increase in rubber and plastic waste has become a serious problem. From the viewpoint of environmental protection, it is a social issue to reuse these rubbers and plastics and to produce no waste as much as possible. Has become a demand.

In the field of electrical cables, especially in power cables, the proportion of plastic insulated power cables is increasing,
As the number of removed cables increases, the need for processing rubber and plastic waste materials such as cross-linked polyethylene insulation layers and protective coating layers is increasing. It is also necessary to treat rubber / plastic waste that overflows from the extruder during rubber / plastic extrusion of plastic insulated power cables.

As a method of recycling rubber / plastic waste, for example, in Japanese Patent Laid-Open No. 2-295720, a waste plastic material crushed to a particle size of 4 mm or less, preferably 0.3 mm in average, is compounded with another resin. However, when the waste plastic is cross-linked, particularly when the degree of cross-linking is high, this method has the drawback that the moldability of the resulting composite material is extremely poor. ing.

Further, Japanese Patent Laid-Open No. 62-260844 discloses that
A method of melting and utilizing a mixture of two or more kinds of polyolefin-based thermoplastic resins having different structures by adding ceramic ultrafine particles is disclosed. However, in this case as well, the crosslinkable polymer cannot be heat-mixed. It is out of scope and has not led to significant progress in the recycling of waste plastics in general.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a rubber used for coating electric wires and cables, which has been difficult to incinerate due to its large calorific value in conventional combustion furnaces.
It is also intended to reuse plastic waste materials, and rubber / plastic waste materials that overflow from the extruder during the production of electric wires / cables. It is intended to provide a rubber / plastic mixture having almost no deterioration in properties as compared with a non-mixed product when used in a mixture with a plastic.

[0007]

In order to solve the above problems, in the present invention, a) rubber / plastic 50 to 9 is used.
Provided is a rubber / plastic mixture comprising 0% by weight and b) 10 to 50% by weight of powder of a rubber / plastic waste material used for coating electric wires / cables having an average particle size of 100 μm or less.

Examples of the rubber / plastic which is the component a) of the present invention include polyvinyl chloride, polyethylene,
Olefin homopolymers such as polypropylene, polybutene-1, poly-4-methyl-pentene-1, and interpolymers such as ethylene, propylene, butene-1, 4-methyl-pentene-1, hexene-1, octene-1. , Copolymers of ethylene with vinyl acetate, unsaturated carboxylic acid, unsaturated carboxylic acid ester, etc., and butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-vinyl acetate One or two or more kinds of admixtures selected from synthetic rubbers such as copolymer rubbers may be mentioned.

The rubber / plastic waste material as the component b) is used for coating electric wires / cables, and its main constituents are low-, medium-, and high-density polyethylene, ultra-low-density polyethylene, and linear low-density polyethylene. It is composed of polyethylene, ethylene-propylene rubber, ethylene-based copolymers such as ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer, and polyvinyl chloride, and one or a mixture of two or more thereof, or a cross-linked product thereof. These rubbers
The waste plastic material is obtained, for example, by collecting the insulating layer or sheath of the removed cable, or the overflow of the extruder when the insulating layer or sheath is extrusion-coated, and pulverizing these.

It is essential that the powder of the rubber / plastic waste material of the component (b) has an average particle size of 100 μm or less. When the average particle size is 100 μm or less, the dispersibility / compatibility with the component a) can be increased to homogenize the mixture, and the defective rate of the appearance after molding can be reduced. Also, rubber
The waste plastic material may contain an inorganic filler or the like, or may be one which is crosslinked by heating after adding an organic peroxide or by irradiation with ultraviolet rays.

In order to pulverize the crosslinked and / or non-crosslinked rubber / plastic waste material used as the component b) of the above rubber / plastic mixture into a desired particle size, it is necessary to prevent the waste material from being dissolved while increasing the high sensibility. It is necessary to make a cut. Therefore, for example, a method of using a bead mill or the like, filling a container with water or an organic solvent that does not dissolve the crosslinked rubber / plastic composition, and pulverizing the container with the outside cooled is preferable.

The blending ratio of the component b) in the mixture is 5
-50% by weight, preferably 10-20% by weight. If the compounding amount is less than 5% by weight, the utilization rate of the waste material in the rubber / plastic mixture is low, and if it exceeds 50% by weight, the characteristics of the component a) as the base material may be impaired, or the fine powder of This is because the desired appearance may not be obtained when the mixture is formed into a molded product due to poor dispersion.

The mixture of the present invention is obtained by melt-kneading the components a) and b) with a Banbury mixer, a pressure kneader, a kneading extruder, a twin-screw extruder, a roll, or the like, which is commonly used, to form pellets. In addition to being used as a sheathing material for electric wires / cables or other molded products, or as a masterbatch, both components may be dry-blended when molding a structure using the mixture of the present invention.

The admixture of the present invention comprises an inorganic filler,
It is also possible to mix an organic flame retardant or the like and reuse it as a flame-retardant resin composition.

In the present invention, other synthetic resins, antioxidants,
Lubricants, various organic / inorganic pigments, UV inhibitors, dispersants, copper damage inhibitors, neutralizing agents, foaming agents, plasticizers, antifoam agents, crosslinking agents, flow improvers, weld strength improvers, cores Additives such as agents may be added to the mixture of components a) and b) as long as the characteristics are not impaired.

[0016]

EXAMPLES Examples of the present invention are shown below.

Example 1 An insulating layer made of cross-linked polyethylene recovered from a 66 kv CV cable (having a gel fraction of 84% obtained by cross-linking low-density polyethylene having a density d = 0.918 g / cm ³ with dicumyl peroxide) was ball-milled. After preliminarily pulverizing to a particle size of 1 mm with, a suspension of water prepared by adjusting the concentration of the crosslinked polyethylene pulverized product to a concentration of 15% by weight is filled in a bead mill container having a volume of 1 liter, and in the presence of 0.2 μm Zr beads. After pulverizing with, the resulting suspension water was sieved to obtain a crosslinked polyethylene fine powder having an average particle size of 7 μm.

The resulting crosslinked polyethylene fine powder was blended in a ratio of 20 parts by weight with respect to 100 parts by weight of an ethylene-ethyl acrylate copolymer having an EA content of 15% by weight, followed by kneading with a Banbury. The kneaded product was sequentially passed through a strand extruder and a pelletizer to obtain a pellet-shaped plastic mixture having an average particle size of 2 mm.

The obtained plastic mixture is made to have a thickness of 1 mm.
After being formed into a sheet of No. 3, it was a test piece punched out with a No. 3 dumbbell, and the tensile speed was 200 mm / min with Tensilon.
As a result of a tensile test, the elongation rate of 675% and the tensile strength of 1.3 kgf / cm ² were obtained. The appearance of the sheet was very good. This value is
With respect to the elongation rate of 820% and the tensile strength of 1.2 kgf / mm ^{2 of the} ethyl acrylate copolymer, 80% or more was maintained in each case, and there was no problem in industrial use.

Example 2 A resin composition overflowing from an extruder when the insulation layer of a 66 kv CV cable was extrusion-coated (density d = 0.
(2 parts by weight of dicumyl peroxide and an antioxidant were previously contained in 100 parts by weight of 918 g / cm ³ low-density polyethylene) were recovered and crosslinked by heating at 180 ° C., and then the particle size was 1 mm with a ball mill. After preliminarily pulverizing the mixture into a bead mill container having a capacity of 1 liter, the cross-linked polyethylene pulverized product was filled with suspension water adjusted to have a concentration of 15 wt%, pulverized in the presence of 0.2 μm Zr beads, and then obtained. The suspended water thus obtained was sieved to obtain a crosslinked polyethylene fine powder having an average particle size of 7 μm.

The obtained crosslinked polyethylene fine powder was mixed with 100 parts of low-density polyethylene having a density d = 0.918 g / cm ^3.
The mixture was mixed at a ratio of 50 parts by weight with respect to parts by weight, and the mixture was kneaded in a Banbury, and the kneaded product was sequentially passed through a strand extruder and a pelletizer to obtain a pellet-shaped plastic mixture having an average particle diameter of 2 mm.

The resulting plastic mixture is 1 mm thick
After being formed into a sheet of No. 3, it was a test piece punched out with a No. 3 dumbbell, and the tensile speed was 200 mm / min with Tensilon.
As a result of a tensile test, the characteristics of elongation of 513% and tensile strength of 1.5 kgf / cm 2 were obtained, and the appearance of the sheet was extremely good. This value is such that the low density polyethylene used as the base material has an elongation of 612% and a tensile strength of 1.5 kgf /
80% or more of each of them was retained with respect to mm ² , and they had properties that would not hinder industrial use.

Example 3 A resin composition (density d = 0. 0) overflowed from an extruder when extrusion-coating an insulating layer of a 66 kv CV cable.
100 parts by weight of low-density polyethylene of 918 g / cm ³ and 2 parts by weight of dicumyl peroxide, which previously contained an antioxidant) were charged in a kneader, and the whole container was placed at 18
After rotating the rotor for 30 minutes while maintaining the temperature at 0 ° C., the low density polyethylene is uniformly crosslinked,
The entire container was cooled with water and cooled to room temperature, and the rotor was again rotated at a low speed to obtain a crosslinked low-density polyethylene fine powder having an average particle size of 20 μm. Further, the obtained crosslinked low-density polyethylene fine powder was treated with a density d = 0.918 g / cm.
A mixture of 20 parts by weight and 100 parts by weight of low-density polyethylene ³ was kneaded in a Banbury, and the kneaded product was sequentially passed through a strand extruder and a pelletizer to obtain pellet-shaped plastic having an average particle diameter of 2 mm. A mixture was obtained.

The resulting plastic mixture is 1 mm thick
After being formed into a sheet of No. 3, it was a test piece punched out with a No. 3 dumbbell, and the tensile speed was 200 mm / min with Tensilon.
As a result of the tensile test, the elongation rate of 525% and the tensile strength of 1.5 kgf / cm ² were obtained. The appearance of the sheet was very good. This value is based on the low-density polyethylene used as the base material, which has an elongation of 612% and a tensile strength of 1.5 kgf / mm.
^{On the} other hand, in both cases, 80% or more was retained, and the characteristics were that there was no problem in industrial use.

Comparative Example 1 A mixture in which the same crosslinked low density polyethylene fine powder as used in Example 3 was blended in a ratio of 50 parts by weight to 100 parts by weight of low density polyethylene having a density d = 0.918 g / cm ³ . After being kneaded in a Banbury, the kneaded product is sequentially passed through a strand extruder and a pelletizer to obtain an average particle size of 2 m.
m pelletized plastic mixture was obtained.

The obtained plastic mixture is made to have a thickness of 1 mm.
After being molded into a sheet of No. 3, it was a test piece punched out with a No. 3 dumbbell, and the tensile speed was 200 mm / mi with Tensilon.
As a result of conducting a tensile test with n, an elongation of 483% and a tensile strength of 1.6 kgf / cm ² were obtained. The sheet had many protrusions in the shape of a twitch. The above value is the elongation 612 of the low density polyethylene used as the base material.
%, A tensile strength of 1.5 kgf / mm ² shows a marked decrease in elongation, and the appearance of the sheet is significantly inferior to that of the base material. Therefore, industrial use requires considerable limitation. Or it was unavailable.

Comparative Example 2 A mixture in which the same crosslinked low density polyethylene fine powder as used in Example 1 was blended in a ratio of 60 parts by weight to 100 parts by weight of low density polyethylene having a density d = 0.918 g / cm ³ . Was kneaded in a Banbury, and the mixture was passed through a strand extruder and a pelletizer in this order to obtain an average particle size of 2 m.
m pelletized plastic mixture was obtained.

The obtained plastic mixture is made to have a thickness of 1 mm.
After being formed into a sheet of No. 3, it was a test piece punched out with a No. 3 dumbbell, and the tensile speed was 200 mm / min with Tensilon.
As a result of a tensile test, a characteristic of elongation 472% and tensile strength 1.6 kgf / cm ² was obtained. The sheet had some protrusions in the shape of a twitch. The above value is the elongation 612 of the low density polyethylene used as the base material.
%, Tensile strength of 1.5 kgf / mm ² markedly decreased elongation, and sheet appearance was slightly inferior to that of the base material. Or it was unavailable.

[0029]

EFFECT OF THE INVENTION In the rubber / plastic mixture of the present invention, the rubber / plastic waste material used for the electric wire / cable coating application, which has been shunned by incineration in the usual combustion furnace due to its large calorific value, is average. The waste material is finely pulverized to have a particle size of 100 μm or less and mixed in an appropriate amount with an unused rubber / plastic, so that the waste material is cross-linked and optionally contains carbon black and other additives.
It can be reused without significantly impairing the properties of the rubber / plastic as the base material. Therefore, it will make a great contribution to the recycling and utilization of rubber / plastics used for electric wire / cable coating applications, which have become a problem in recent years.

Claims (1)

[Claims] 1. A) 50 to 90% by weight of rubber / plastic, and b) 10 to 50% by weight of powder of waste rubber / plastic used for electric wire / cable coating applications having an average particle size of 100 μm or less. Rubber / plastic mixture.