JP2001098124A - Thermoplastic resin composition for electric wires and electric wires coated with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition for electric wires that comprises polyvinyl chloride resins and polyethylene resin recovered from waste electric wires and is made recyclable without sorting and provide the electric wires coated with the resin composition as an insulating material or coating material. SOLUTION: The objective thermoplastic resin composition comprises (1) 1-99 pts.wt. of a resin composition mainly including the polyvinyl chloride resin and the polyethylene resin recovered from the waste electric wires, (2) 1-99 pts.wt. of a multilayered structure type of graft copolymer including 5-95 wt.% of segment A of a thermoplastic elastomer and 1-99 wt.% of the segment B of a vinyl (co)polymer where one segment is dispersed in the other matrix segment in particle forms with a particle size of 0.001-10 μm. Electric wires are coated with this thermoplastic resin composition as an insulating or covering material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition for electric wires, which is capable of reusing polyvinyl chloride resin and polyethylene resin recovered from waste electric wires without separation and having excellent mechanical properties. And an electric wire using the same as an insulator or a covering.

[0002]

2. Description of the Related Art In general, a polyvinyl chloride resin, a polyethylene resin, or the like is used as a single layer or a composite layer in an insulator portion of an electric wire. Conventionally, in the recycling of electric wires, only copper, which is a conductor, is collected, and resin in an insulator is often buried or incinerated. However, in recent years, the shortage of landfill sites and environmental problems due to exhaust gas generated during combustion of polyvinyl chloride resin have been highlighted, and the resin used as an insulator has been reused.

There are two methods for recycling resin recovered from waste electric wires. One is a method in which all the resins are collectively collected, crushed and reused. Another method is a method of separating and collecting the resin constituting the electric wire for each type and reusing the resin. This is a method in which the covering material of the electric wire is separated in a manner of peeling the skin into portions such as a sheath material and an insulator (generally called a "peeling"), and the obtained material is crushed.

[0004]

The method of collectively collecting and pulverizing all the resin from the waste electric wire is not problematic in the case of an electric wire composed of only one kind of resin, but an electric wire covered with a plurality of resins. In case (1), the mechanical properties of the recovered resin, particularly the elongation at the time of tension, were significantly inferior to those of the virgin material, so that the recovered resin could not be reused for electric wires. On the other hand, the mechanical properties of the resin separated and recovered according to the type are not significantly reduced as compared with the virgin material, and thus the resin can be reused as an electric wire. However, since this method is very complicated and costly, it is not practiced much. SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic resin composition for electric wires which can be reused without separating polyvinyl chloride resin and polyethylene resin recovered from distribution lines, and has excellent mechanical properties, and an insulator for the same. Another object of the present invention is to provide an electric wire used as a covering.

[0005]

Means for Solving the Problems In order to solve the above problems, the first invention provides (1) a resin composition mainly composed of a polyvinyl chloride resin and a polyethylene resin recovered from waste electric wires. A graft copolymer comprising 1 to 99% by weight and (2) 5 to 99% by weight of an A segment which is a thermoplastic elastomer and 1 to 95% by weight of a B segment which is a vinyl (co) polymer; One segment has a particle size of 0.001 to 10 μm in the other segment.
Structure type graft copolymer 1 forming a dispersed phase of
It is a thermoplastic resin composition for electric wires consisting of up to 99% by weight. A second invention is the thermoplastic resin composition for electric wires according to the first invention, wherein the A segment is a polystyrene elastomer. A third invention is the thermoplastic resin composition for electric wires according to the first invention or the second invention, wherein the B segment is a (co) polymer formed from a (meth) acrylate. A fourth invention is an electric wire using the thermoplastic resin composition for an electric wire according to any one of the first invention to the third invention as an insulator or a covering.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A resin composition mainly composed of a polyvinyl chloride resin and a polyethylene resin (hereinafter abbreviated as “recovered resin”) recovered from waste electric wires used in the present invention is referred to as “recovered resin”. It is a recovered resin and contains only a polyvinyl chloride resin or a polyethylene resin, or contains both a polyvinyl chloride resin and a polyethylene resin as main components. . The content of the polyvinyl chloride resin in the recovered resin is usually 5 to 95% by weight. The polyvinyl chloride resin may be a homopolymer of vinyl chloride, a copolymer with another monomer copolymerizable with vinyl chloride, or a mixture thereof. Other monomers copolymerizable with vinyl chloride, for example, propylene, olefins such as butene,
Fatty acid vinyl esters such as vinyl acetate, unsaturated acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid, unsaturated acid esters such as methyl acrylate, unsaturated anhydrides such as maleic anhydride, and nitrile compounds such as acrylonitrile Alkyl vinyl ethers such as methyl vinyl ether and cetyl vinyl ether; and vinylidene compounds such as vinylidene chloride.

Examples of the polyethylene resin include low-density polyethylene, ultra-low-density polyethylene, ultra-low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ultra-high-molecular-weight polyethylene, and polyethylene synthesized with a metallocene catalyst. Can be mentioned.
These polyethylenes may be used as a mixture or may be partially crosslinked.

[0008] In the recovered resin, polyvinyl chloride resin,
In addition to the polyethylene resin and the like, other resins such as a thermoplastic elastomer such as an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-propylene rubber may be contained. The content of the other resin in the recovered resin is usually 0 to 30% by weight.

The multi-phase structure type graft copolymer referred to in the present invention may be a thermoplastic elastomer A segment or a vinyl (co) polymer (herein, the term “(co) polymer” refers to a polymer or a copolymer). Is a graft copolymer in which one segment constitutes a matrix and one segment forms a dispersed phase with a specific particle size in the other segment.

The specific particle size is 0.001 to 10 μm.
m, preferably 0.01 to 5 μm. When the particle size of the dispersed resin is less than 0.001 μm or more than 10 μm, the compatibility with the polyvinyl chloride resin or the polyethylene resin is reduced, so that the desired mechanical properties cannot be maintained. There is a tendency.

The thermoplastic elastomer which is the A segment includes, for example, a polyolefin elastomer,
Polystyrene elastomer, polyester elastomer, polyamide elastomer, polyurethane elastomer and the like. Among these thermoplastic elastomers, a polystyrene-based elastomer is preferable because of its high effect of improving mechanical properties. These thermoplastic elastomers are 1
Species or a mixture of two or more can be used.

The above-mentioned polystyrene-based elastomer is a block copolymer containing at least one polymer of a vinyl aromatic monomer and at least one polymer of a conjugated diene. It may be a type. Further, the polymer containing the conjugated diene may be a random copolymer with a small amount of a vinyl aromatic monomer, or a so-called tapered block copolymer in which the vinyl aromatic monomer gradually increases. It doesn't matter. In the above block copolymer, it is also possible to use a block copolymer in which the conjugated diene portion has been hydrogenated.

The vinyl (co) polymer as the B segment is obtained by copolymerizing at least one selected from vinyl monomers. Examples of the vinyl monomer include vinyl aromatic monomers such as styrene; nuclear-substituted styrenes such as methylstyrene, dimethylstyrene, ethylstyrene, isopropylstyrene, and chlorostyrene; α-methylstyrene, α-ethylstyrene, and the like. Α-substituted styrene; methyl (meth) acrylate,
(Meth) acrylic acid esters such as ethyl (meth) acrylate, (meth) acrylic acid and esters of alkyl alcohols having 3 to 20 carbon atoms; (meth) acrylonitrile;
And vinyl esters such as vinyl acetate and vinyl propionate. Among these monomers, (meth) acrylic acid ester monomers can be mentioned as preferred vinyl monomers from the viewpoint of compatibility with the polyvinyl chloride resin.

The weight average molecular weight of the B-segment vinyl (co) polymer in the present invention is usually from 1,000 to 1,000.
1,000,000, preferably 5,000-500,
000, more preferably 7,000-300,000
Range. In both cases where the weight average molecular weight is less than 1,000 and when it exceeds 1,000,000, the compatibility with the polyvinyl chloride resin tends to decrease.

The multi-phase structure type graft copolymer of the present invention comprises:
A segment is usually 5 to 99% by weight, preferably 20 to 99% by weight.
The B segment is usually 1 to 95% by weight, preferably 5 to 80% by weight.

If the content of the A segment is less than 5% by weight, the compatibility with the polyethylene resin tends to decrease.
If the segment exceeds 99%, the compatibility with the polyvinyl chloride resin tends to decrease.

The method for producing the multi-phase structure type graft copolymer of the present invention may be any of the generally known methods such as chain transfer method and ionizing radiation irradiation method. It is due to. Because the graft efficiency is high and secondary aggregation by heat does not occur,
This is because the expression of performance is more effective and the production method is simple.

Next, the method for producing the thermoplastic resin composition for electric wires of the present invention will be specifically described in detail. That is, 100 parts by weight of particles of a thermoplastic elastomer are suspended in water, and 1 to 400 parts by weight of at least one vinyl monomer is separately added.
0.1 to 20 parts by weight of 100 parts by weight of the vinyl monomer, and one or more kinds of radically polymerizable organic peroxides represented by the following general formula 1 or 2;
Decomposition temperature for obtaining a half-life of 10 hours is 40 to 90 ° C
0.01 to 5 parts by weight per 100 parts by weight of the total of the vinyl monomer and the radical polymerizable organic peroxide.
Parts by weight and a solution in which the polymerization initiator is dissolved is heated under conditions where decomposition of the polymerization initiator does not substantially occur.
A radical polymerizable organic peroxide and a polymerization initiator are impregnated into the copolymer particles, and when the impregnation rate reaches 50% by weight or more of the initial addition amount, the temperature of the aqueous suspension is increased, Vinyl monomer and radical polymerizable organic peroxide in the thermoplastic elastomer particles (co)
It is polymerized to obtain a grafting precursor. By melting and kneading the grafting precursor at 100 to 300 ° C., a multiphase structure type graft copolymer composed of an A segment and a B segment is obtained.

However, the grafting precursor need not necessarily be melt-kneaded before being mixed with the recovered resin. That is, the grafting precursor may be directly melt-mixed with the recovered resin. This is because the grafting precursor becomes a graft copolymer even by melt-kneading with the recovered resin.

The grafting precursor was added to separately synthesized A
Has the same structure as segment or B segment (co)
Even if the polymers are mixed and kneaded under melting, a multi-phase structure type graft copolymer can be obtained. Further, in the above polymerization process, a grafting precursor is synthesized without using a vinyl-based monomer, and the grafting precursor and the vinyl monomer are mixed and melt-kneaded. Coalescence can be obtained. Most preferred is a multiphase structure type graft copolymer obtained by melt-kneading the grafting precursor.

The thermoplastic resin composition for electric wires of the present invention can be obtained by melt-kneading the multiphase structure type graft copolymer thus obtained and the recovered resin. The radically polymerizable organic peroxide represented by the general formula 1 is the following compound.

[0022]

Embedded image

In the formula, R ¹ is a hydrogen atom or a group having 1 to 2 carbon atoms.
R ² is a hydrogen atom or a methyl group; R ³ and R ⁴ are each an alkyl group having 1 to 4 carbon atoms; R ⁵ is an alkyl group having 1 to 12 carbon atoms, a phenyl group, an alkyl-substituted phenyl group or a carbon atom; Shows cycloalkyl groups of the numbers 3 to 12. m is 1 or 2.

The radically polymerizable organic peroxide represented by the general formula 2 is the following compound.

[0025]

Embedded image

In the formula, R ⁶ is a hydrogen atom or a carbon atom having 1 to 4 carbon atoms.
R ⁷ is a hydrogen atom or a methyl group; R ⁸ and R ⁹ are each an alkyl group having 1 to 4 carbon atoms; R ¹⁰ is an alkyl group having 1 to 12 carbon atoms, a phenyl group, an alkyl-substituted phenyl group or a carbon atom; Shows cycloalkyl groups of the numbers 3 to 12. n is 0, 1 or 2.

Specific preferred examples of the radically polymerizable organic peroxide represented by Formula 1 or 2 include t-butylperoxyacryloyloxyethyl carbonate; t-butylperoxymethacrylic acid. Leuroxyethyl carbonate; t-butyl peroxyallyl carbonate
Bones; t-butyl peroxymethacrylic acid-bone
It is.

The content of the multi-phase structure type graft copolymer in the thermoplastic resin composition for electric wires of the present invention is usually from 1 to 1.
99% by weight. From the viewpoint of recycling waste electric wires, the content is more preferably 1 to 50% by weight. When the content of the multi-phase structure type graft copolymer is less than 1% by weight, the compatibility between the polyvinyl chloride resin and the polyethylene resin becomes low, and when it exceeds 99% by weight, it tends to be economically disadvantageous. .

The thermoplastic resin composition for electric wires of the present invention is produced by melting and mixing at a temperature of 150 to 350 ° C. If the temperature is lower than 150 ° C., the melting is incomplete or the melt viscosity is high, the mixing becomes insufficient, and phase separation or delamination appears in the molded product, which is not preferable. On the other hand, when the temperature exceeds 350 ° C., decomposition or gelation of the mixed resin occurs, which is not preferable.

As a method of melting and mixing, Banbury
It can be carried out by a commonly used kneading machine such as a mixer, a pressure kneader, a kneading extruder, a twin-screw extruder or a roll. In the present invention, within the scope not further deviating from the gist of the present invention, inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide, halogen-based, organic flame retardants such as phosphorus-based, metal powder, antioxidant, ultraviolet ray inhibitor, Lubricants, dispersants, coupling agents, foaming agents, crosslinking agents, coloring agents, additives such as carbon black and the like may be added.

The electric wire of the present invention uses the above-mentioned thermoplastic resin composition for an electric wire as an insulator or a coating.

[0032]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. The abbreviations in the table represent the following substances. SEPS: styrene-hydrogenated isoprene-styrene triblock copolymer (trade name: Septon 2063,
SEBS: Styrene-hydrogenated butadiene-styrene triblock copolymer (trade name: Clayton G1657, manufactured by Kuraray Co., Ltd.)
Shell Japan Co., Ltd.) TPU: Thermoplastic polyurethane elastomer (trade name:
(Churamilon U816, manufactured by Kuraray Co., Ltd.) TPE: olefin-based thermoplastic elastomer (trade name:
TPE3885, manufactured by Sumitomo Chemical Co., Ltd.) MMA: methyl methacrylate BMA: butyl methacrylate St: styrene MAA: methacrylic acid

Reference Example 1 (Production of Graft Copolymer of Multi-Phase Structure Type) In a stainless steel autoclave having a volume of 5 liters, 2500 g of pure water was added, and 2.5 g of polyvinyl alcohol as a suspending agent was further added. Dissolved. 800 g of a styrene-hydrogenated isoprene-styrene triblock copolymer (trade name: Septon 2063) was put therein, and stirred and dispersed. Separately, 1.5 g of benzoyl peroxide as a polymerization initiator and t-butyl peroxymethacryloyloxyethyl carbonate 4 as a radical polymerizable organic peroxide.
g as a vinyl monomer in methyl methacrylate 200
g, and the solution was charged and stirred into the autoclave.

Then, the autoclave was heated to 60 to 65 ° C. and stirred for 2 hours to convert the polymerization initiator, the radically polymerizable organic peroxide and the vinyl monomer into styrene.
Impregnated in hydrogenated isoprene-styrene triblock copolymer. Next, after confirming that the total amount of the impregnated vinyl monomer, the radical polymerizable organic peroxide and the polymerization initiator is 50% by weight or more of the initial addition amount, the temperature is raised to 80 to 85 ° C. The temperature was raised for 4 hours to complete the polymerization, washed with water and dried to obtain a graft precursor. Polymethyl methacrylate was extracted from the grafted precursor with tetrahydrofuran, and the weight average molecular weight was measured by gel permeation chromatography (GPC) to be 100,000.

Next, this grafted precursor was subjected to a Labo Plastomill single screw extruder (manufactured by Toyo Seiki Seisaku-sho, Ltd.) for 20 minutes.
It was extruded at 0 ° C. and subjected to a grafting reaction to obtain a multi-phase structure type graft copolymer.

This is called a scanning electron microscope “JEOL JS
As a result of observation with “MT300” (manufactured by JEOL Ltd.), it was a multiphase graft copolymer in which spherical resins having a particle diameter of 0.3 to 0.4 μm were uniformly dispersed. At this time, the grafting efficiency of the methyl methacrylate polymer was 75
% By weight.

Reference Examples 2 to 13 (Preparation of Graft Copolymer of Multi-Phase Structure Type) In the same manner as in Reference Example 1, a styrene-hydrogenated isoprene-styrene triblock copolymer as an A segment and a B segment were obtained. Tables 1-4 show methyl methacrylate.
The multiphase structure type graft copolymer was synthesized by changing the components and ratios shown in the above. Further, the weight average molecular weight, the particle diameter, and the graft efficiency were measured in the same manner as in Reference Example 1 and are shown in Tables 1 to 4.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

[0041]

[Table 4]

Example 1 (Production of Thermoplastic Resin Composition for Electric Wire) Referenced to 950 g of recovered resin (a resin part was collectively collected from waste electric wires and contained 70% by weight of polyethylene and 30% by weight of polyvinyl chloride). After dry-blending 50 g of the multiphase structure type graft copolymer synthesized in Example 1, the cylinder was set to a temperature of 210 ° C. and the screw diameter was 30 mm.
And extruded after extrusion. A test piece (size of a No. 2 type tensile test piece: 115 mm × 25 m) was obtained from the granulated resin using an injection molding machine having a cylinder temperature of 210 ° C.
mx 3 mm), and a tensile test was performed according to JIS K7113. The results are shown in Table 5.

(Production and evaluation of electric wire) 500 g of the granulated resin composition, 500 g of magnesium hydroxide, carbon 2
0g was blended, and an electric wire made of a copper wire having a cross section of 8mm ² was coated with a thickness of 1.2mm using an extruder for electric wire production set at a cylinder temperature of 200 ° C. The results were evaluated and the results are shown in Table 5. The evaluation criteria were as follows. Extrusion processability: も の indicates good, や indicates slightly difficult, and × indicates poor. Flexibility: 良好 indicates good, 、 indicates slightly difficult, and × indicates poor.

[0044]

[Table 5]

Examples 2 to 12 (Production of thermoplastic resin composition for electric wire) The multiphase structure type graft copolymer and the recovered resin were melt-kneaded at the ratios shown in Tables 5 to 8, and the same as in Example 1 A test piece was prepared by the method described above. Thereafter, a tensile test and production and evaluation of an electric wire were performed in the same manner as in Example 1, and the results were shown in Tables 5 to 8.
It was shown to.

[0046]

[Table 6]

[0047]

[Table 7]

[0048]

[Table 8]

Comparative Examples 1 to 4 A test piece was prepared in the same manner as in Example 1 by melt-kneading the multi-phase structure type graft copolymer and the recovered resin in the proportions shown in Table 9, and the same as in Example 1. The tensile test and the production and evaluation of the electric wire were performed by the method described in Table 1, and the results are shown in Table 9.

[0050]

[Table 9]

As described above, the thermoplastic resin for electric wires of the present invention is superior in mechanical properties and workability as compared with the comparative example.
Therefore, it is suitable as an insulator or a covering for electric wires.

[0052]

The thermoplastic resin composition for electric wires according to the present invention comprises:
Excellent mechanical properties and workability, especially elongation at the tensile break point, and also made it possible to reuse the recovered resin from waste wire without re-sorting it as an electric wire. I have.

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Claims (4)

[Claims] (1) 1 to 99% by weight of a resin composition mainly composed of a polyvinyl chloride resin and a polyethylene resin recovered from waste electric wires, and (2) A segment 5 which is a thermoplastic elastomer. A graft copolymer comprising 99% by weight and 1 to 95% by weight of a B segment which is a vinyl (co) polymer, wherein said one segment has a particle size of 0.001 to 10 µm in the other segment. Having a multiphase structure type graft copolymer 1-9
9% by weight of a thermoplastic resin composition for electric wires. 2. The thermoplastic resin composition for an electric wire according to claim 1, wherein the A segment is a polystyrene elastomer. 3. The thermoplastic resin composition for an electric wire according to claim 1, wherein the B segment is a (co) polymer formed from a (meth) acrylate. 4. An electric wire using the thermoplastic resin composition for an electric wire according to claim 1 as an insulator or a covering.