JP2012221679A - Manufacturing method of wire and cable using reclaimed resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of wire and cable using a reclaimed resin which can be applied to the coating material for wire and cable, by controlling the gel fraction of the reclaimed resin appropriately thereby enhancing the environmental stress cracking resistance.SOLUTION: In the manufacturing method of wire and cable using a reclaimed resin obtained by decomposing the crosslinked portion of a silane crosslinked resin by alcohol or carbonic acid ester, extrusion molding is performed so that the gel fraction of a coating material immediately after extruding to a conductor by using the reclaimed resin is 1.0-20.5%.

Description

  The present invention relates to an electric wire / cable manufacturing method using a regenerated resin obtained from a silane cross-linked resin.

  Needless to say, effective use and recycling of resources is important in today's society where efforts to deal with environmental issues are being promoted globally. Resin materials are no exception, and many materials are recycled by various methods.

  Polyethylene, which is a general-purpose resin material, is a material excellent in electrical insulation, and is widely used as a coating material for electric wires and cables. Cross-linked polyethylene imparted with heat resistance by three-dimensionally cross-linking polyethylene molecules is also used in large quantities as a wire / cable coating material.

  Since polyethylene is usually thermoplastic, it can be molded again and is widely recycled. However, cross-linked polyethylene is not thermoplastic, so material recycling has not progressed much, and most of it is landfilled and incinerated. Will be disposed of.

  In recent years, with regard to such cross-linked polyethylene, a movement to carry out material recycling has increased, and a technology that makes this possible is also appearing. For example, a technique of making plastics by cutting molecular chains of crosslinked polyethylene using the shearing force of a screw in an extruder (Patent Document 1) or contacting crosslinked polyethylene with supercritical water in a reactor. In order to obtain an oily fuel (Patent Document 2), by contacting with a supercritical or subcritical high-temperature alcohol or carbonate ester, a siloxane bond, which is a crosslink of a silane cross-linked polymer, is selectively cut to cause thermoplasticity. Patent Documents 3 and 4 show a method for realizing the above.

  In particular, in a thermoplastic method using high-temperature alcohol or carbonate, there is little decrease in the molecular weight of polyethylene, so that a recycled polyethylene having good mechanical properties can be obtained. For this reason, there is no particular need for a blend of virgin materials to compensate for mechanical properties, and recycled polyethylene alone can be used for various purposes.

Japanese Patent No. 3026270 JP-A-6-279762 JP 2002-187976 A JP 2010-001385 A Japanese Patent No. 4102260

  However, since such recycled polyethylene (recycled resin) has a lower molecular weight than the virgin material and the environmental stress crack resistance is reduced, it is difficult to use it directly as a coating material for electric wires and cables. .

  Therefore, the object of the present invention is to solve the above-mentioned problems and to appropriately control the gel fraction of such a recycled resin, thereby improving the environmental stress cracking resistance and being applied to coating materials for electric wires and cables. An object of the present invention is to provide an electric wire / cable manufacturing method using a regenerated resin.

  In order to achieve the above object, the invention of claim 1 is directed to a method of manufacturing an electric wire / cable using a regenerated resin obtained by decomposing a cross-linked portion of a silane cross-linked resin with an alcohol or a carbonic acid ester. Alternatively, a method of manufacturing an electric wire / cable using a regenerated resin, wherein the gel fraction of the coating material immediately after extrusion onto the electric wire core is extruded to be 1.0% to 20.5% It is.

  In the invention of claim 2, the gel fraction of the recycled resin is 0%, and the gel fraction of the coating material immediately after the recycled resin is extruded onto a conductor or electric wire core is 1.0% or more and 20.5. The method for producing an electric wire / cable using the recycled resin according to claim 1, wherein the extrusion temperature at the time of extrusion formation is adjusted so as to be not more than%.

  The invention of claim 3 adds a cross-linking agent and a cross-linking catalyst to the regenerated resin at the time of forming the extrusion, adjusts the extrusion temperature in the extruder, and applies the coating material immediately after extruding the regenerated resin onto a conductor or a wire core. The method for producing an electric wire / cable using the recycled resin according to claim 1 or 2, wherein the gel fraction is 1.0% or more and 20.5% or less.

  According to the invention of claim 4, the regenerated resin obtained by decomposing the crosslinked part of the silane crosslinked resin with alcohol has a temperature in the extruder of 160 ° C. or higher and 205 ° C. or lower, and the die part that has the highest temperature inside the extruder. The method for producing an electric wire / cable using the recycled resin according to any one of claims 1 to 3, wherein the extrusion is performed by controlling the temperature to 180 ° C or higher and 205 ° C or lower.

  The invention according to claim 5 is a die part in which a regenerated resin obtained by decomposing a cross-linked part of a silane cross-linked resin with a carbonic acid ester has a temperature inside the extruder of 160 ° C. or higher and 210 ° C. or lower and the highest temperature inside the extruder. The method of manufacturing an electric wire / cable using the regenerated resin according to any one of claims 1 to 3, wherein the temperature is controlled to be 180 ° C or higher and 210 ° C or lower.

  According to the invention of claim 6, the cross-linking agent and the cross-linking catalyst are not added to the regenerated resin at the time of the extrusion forming, the extrusion temperature in the extruder is adjusted, and the coating material immediately after the regenerated resin is extruded onto the conductor or the wire core. The method for producing an electric wire / cable using the recycled resin according to claim 1 or 2, wherein the gel fraction is 1.0% or more and 20.5% or less.

  According to the seventh aspect of the present invention, there is provided a recycled resin obtained by decomposing a cross-linked portion of a silane cross-linked resin with an alcohol in a die portion that has an extruder internal temperature of 180 ° C. or higher and 205 ° C. or lower and the highest temperature inside the extruder. 7. The method for producing an electric wire / cable using the recycled resin according to claim 1, wherein the extrusion is performed by controlling the temperature to 190 ° C. or higher and 205 ° C. or lower.

  The invention according to claim 8 is a die portion in which a regenerated resin obtained by decomposing a cross-linked portion of a silane cross-linked resin with a carbonic acid ester has a temperature in the extruder of 180 ° C. or higher and 210 ° C. or lower and the highest temperature inside the extruder. The method of manufacturing an electric wire / cable using the regenerated resin according to any one of claims 1, 2, and 6, wherein the temperature is controlled to 190 ° C or higher and 210 ° C or lower.

  In the present invention, when a wire / cable is produced using a regenerated resin obtained by decomposition treatment with alcohol or carbonate using a silane cross-linked resin as a raw material, the gel fraction of the coating material immediately after extrusion onto the conductor is 1. By extruding so as to be 0% or more and 20.5% or less, an excellent effect is obtained that it is possible to obtain an electric wire / cable with improved environmental stress crack resistance.

The schematic diagram of the apparatus used for preparation of an electric wire and a cable using the reproduction | regeneration polyethylene in the Example and comparative example of this invention is shown. It is explanatory drawing of the cylinder temperature of the extruder in FIG.

  Hereinafter, a preferred embodiment of the present invention will be described in detail.

  First, the inventors have made a recycled resin having thermoplasticity from a silane cross-linked resin by reacting with a solvent in a supercritical or subcritical state as shown in Patent Document 3 or Patent Document 4, particularly alcohol or carbonate as a solvent. When manufacturing electric wires / cables using recycled resin obtained by using the above, the extrusion temperature at the time of extrusion coating of the recycled resin on the conductors of electric wires / cables is controlled, so that It has been found that by increasing the gel fraction of the recycled resin, the environmental stress crack resistance of the coating material made of the recycled resin can be improved without mixing the virgin material.

  For this purpose, the environmental stress cracking resistance of the wire / cable coating material is improved by controlling the gel fraction of the recycled resin coating material immediately after extrusion coating to 1.0% or more and 20.5% or less. And it discovered that generation | occurrence | production of a burn (local crosslinked material) could be suppressed, and came to the invention.

  That is, when extruding a coating material made of a regenerated resin decomposed with alcohol or carbonate using a silane cross-linked resin as a decomposition solvent as a coating material for electric wires or cables, for example, by adjusting the temperature in the extruder, By using a coating material in which the gel fraction immediately after coating is controlled to be 1.0% or more and 20.5% or less as a coating material on a conductor or an electric wire core, an electric wire / cable excellent in environmental stress crack resistance can be obtained. It is something that can be done.

  Here, the regenerated resin obtained by decomposing the silane cross-linked resin used in the present invention will be described.

Silane cross-linked resin:
The silane cross-linked resin is obtained by grafting a silane compound onto a polymer using a radical generator and then cross-linking main chains of the polymer with siloxane bonds by the action of a silanol condensation catalyst.

  Here, the resin before cross-linking used as a raw material of the silane cross-linking resin is polyethylene, polypropylene, chlorinated polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-propylene copolymer, or ethylene. -An olefin resin selected from octene copolymers or the like, or a copolymer using these may be used alone or in combination of two or more.

  As the crosslinking agent, a silane compound or a radical generator for grafting the silane compound onto the resin is used. As the silane compound, an organic silane having a vinyl group such as vinyltrimethoxysilane and vinyltriethoxysilane is used, and a radical generator for grafting the silane compound onto polyolefin is dicumyl peroxide, 2,5- Dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (t-butylperoxy) hexane, α, α′-bis (t-butylperoxy) Radical generators such as dialkyl peroxides such as (-m-isopropyl) benzene, m- (t-butylperoxyisopropyl) -isopropylbenzene, p- (t-butylperoxyisopropyl) -isopropylbenzene, dicumyl, etc. A combination of more than one species is used.

  Examples of crosslinking catalysts include Group II such as magnesium and calcium, Group VIII such as cobalt and iron, or elements and metal compounds such as tin, zinc and titanium, metal salts of octylic acid or adipic acid, amine compounds, acids, etc. Can be mentioned. More specifically, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctate, stannous acetate, stannous cabrylate, lead naphthenate, zinc caprylate, cobalt naphthenate, ethylamine, dibutylamine, hexylamine, Inorganic acids such as pyridine, sulfuric acid and hydrochloric acid, and organic acids such as toluenesulfonic acid, acetic acid, stearic acid and maleic acid are used.

  These crosslinking agents and crosslinking catalysts can be used both when the resin before decomposition treatment is silane-crosslinked and when the silane crosslinked resin is regenerated and further re-crosslinked. .

Decomposition treatment method of silane cross-linked resin:
A method for decomposing silane cross-linked resin is, for example, as described in Patent Document 5, in which a cross-linked resin is introduced from a hopper into an extruder, a decomposition solvent is injected, and thereby the cross-linked resin is decomposed. In Patent Document 5, supercritical or subcritical alcohol, water, carbon dioxide, nitrogen, or the like is used as a decomposition solvent. However, the regenerated resin used for the coating material of the electric wire or the like of the present invention is a supercritical or subcritical resin. A product decomposed with an alcohol or a carbonic acid ester is used.

  The solvent for decomposing the silane cross-linked resin is preferably an alcohol or a carbonate ester. Examples of the alcohol include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, One or more alcohols selected from n-pentyl alcohol and i-pentyl alcohol. Examples of the carbonic acid ester include dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

Recycled resin:
As a raw material of the regenerated resin used in the coating material of the present invention, the silane cross-linked resin is used by decomposing the silane cross-linked resin using alcohol or carbonate as a decomposition solvent, so that the main chains of the silane cross-linked resin polymers Since only the part of the siloxane bond that forms a crosslink (the part where the molecule is bonded to the H-type) can be selectively decomposed, while the crosslinking point is decomposed, the part other than the crosslink (such as the main chain of the polymer) This is because the resin is not cleaved, so that a decrease in molecular weight can be suppressed, and a recycled resin that maintains the original physical properties of the polymer can be obtained.

  Table 3 shows the characteristic values of the regenerated resin obtained by decomposing the silane crosslinked resin with methanol or dimethyl carbonate under the conditions shown in Table 2. As shown in Table 3, a regenerated resin obtained by decomposing a silane crosslinked resin with a supercritical or subcritical carbonate has a molecular weight of 15,000 to 38000, an elongation of 350 to 580%, and is a supercritical or subcritical alcohol. The decomposed recycled resin has a molecular weight of 15,000 to 44000 and an elongation of 350 to 650%. Recycled resin decomposed with alcohol has a slightly higher molecular weight after decomposition, but all are regenerated resins, but have high molecular weight, high elongation, and retain their properties even after decomposition. I understand.

  On the other hand, for example, when the cross-linked resin is decomposed by shearing or the like, not only the cross-linking point of the cross-linked resin but also the main chain of the polymer is cut, so that the gel fraction is reduced but the molecular weight is also reduced. It becomes resin. The molecular weight of the recycled resin that has been sheared and decomposed is about 1000 or less, and the elongation is also about 100%. In order to form such a recycled resin as a coating material, it is necessary to mix a virgin material with the recycled resin.

  The regenerated resin obtained by decomposing the silane cross-linked resin used in the present invention has a gel fraction of 0% because the cross-linking points are decomposed. However, by using alcohol or carbonate as a decomposing solvent, Since the point is selectively decomposed and the main chain of the polymer remains, it can be a regenerated resin in which a decrease in molecular weight is suppressed.

  Therefore, in the present invention, since a high molecular weight recycled resin can be obtained by decomposing the silane cross-linked resin with an alcohol or a carbonic ester, a covering material such as an electric wire can be formed without using a virgin material. .

  Excellent resistance to environmental stress cracking by controlling the gel fraction of the coating material immediately after extrusion to 1.0% or more and 20.5% or less when coating the recycled resin on the conductor or wire core Electric wires and cables can be provided.

  Further, there is no problem even if the recycled resin of the present invention is appropriately blended with a resin excellent in environmental stress crack resistance. However, this lowers the ratio of recycled resin in the coating material, which makes the method less environmentally significant.

  Next, a method for manufacturing electric wires and cables using recycled resin will be described.

  Recycled resin obtained by decomposing silane cross-linked resin with alcohol or carbonic acid ester as a coating material for electric wires / cables and extruding on conductors or electric wire cores using an extruder. When using a resin, it is preferably controlled at 160 ° C. or higher and 205 ° C. or lower, and when using a regenerated resin decomposed with a carbonate, it is preferably controlled at 160 ° C. or higher and 210 ° C. or lower. More preferably, the die part at the highest temperature is controlled to 180 ° C. or higher and 205 ° C. or lower when using a recycled resin decomposed with alcohol, and 180 ° C. or higher and 210 ° C. or lower when using a recycled resin decomposed with a carbonic ester. It is good to control.

  In particular, in the case of a silane cross-linked resin in which dicumyl peroxide having a half-life (10 hours) temperature of about 120 ° C. is used as a radical generator, it is decomposed, and when the recycled resin is extruded, This is because when the temperature is lower than 160 ° C., radicals are hardly generated in the regenerated resin, re-crosslinking reaction hardly occurs, and control of the gel fraction becomes difficult. When it is desired to perform extrusion at a temperature lower than 160 ° C., it goes without saying that the lower the half-life (10 hours) temperature, the more efficient the generation of radicals, the melting point of the resin. As the temperature approaches the softening point and the viscosity rises and the melting becomes insufficient, the extrusion molding itself becomes difficult. Further, when the temperature is 205 ° C. or higher or higher than 210 ° C., the crosslinking reaction proceeds excessively, and burns occur in the extruded coating material.

  When a regenerated resin derived from a silane cross-linked resin is used as an electric wire / cable coating material and extruded onto a conductor or electric wire core, a silane compound is grafted into the regenerated resin without adding a cross-linking agent and a cross-linking catalyst. Therefore, the alkoxysilane and silanol groups in the silane compound latent in the recycled resin undergo a condensation reaction mainly due to the heat of the extruder when forming the coating material, so that the siloxane bond is formed between the polymer molecular chains (main chains). Since (crosslinking) is formed and recrosslinking is performed, the regenerated resin can be recrosslinked without using a crosslinking agent and a crosslinking catalyst.

  By omitting the step of adding the crosslinking agent and the crosslinking catalyst, the working efficiency can be increased.

  Recycled resin obtained by decomposing silane cross-linked resin with supercritical or subcritical alcohol or carbonic acid ester decomposes the cross-linking points and leaves the polymer main chain part. A high-molecular-weight coating material can be produced simply by adjusting and re-crosslinking.

  If the extrusion temperature of the coating material made of recycled resin is low, the latent silane compound does not react easily and it is difficult to re-crosslink, so the temperature inside the extruder when extrusion coated onto a conductor or wire core is recycled with alcohol decomposed. When using a resin, it is preferably controlled at 180 ° C. or higher and 205 ° C. or lower, and when using a regenerated resin decomposed with a carbonate, it is preferably controlled at 180 ° C. or higher and 210 ° C. or lower. More preferably, the die portion at the highest temperature is controlled to 190 ° C. or higher and 205 ° C. or lower when using a recycled resin decomposed with alcohol, and 190 ° C. or higher and 210 ° C. or lower when using a recycled resin decomposed with a carbonate ester. It is good to control.

  It is possible to set the temperature in the extruder to 160 ° C. or higher. At that time, if the inside of the extruder is less than 180 ° C., particularly the die part is less than 190 ° C., alkoxysilane and silanol in the silane compound latent in the recycled resin. Since the group does not easily undergo a re-crosslinking reaction and the gel fraction of the coating material after molding becomes low, it is necessary to add a crosslinking agent and a crosslinking catalyst again at the time of extrusion molding.

  Furthermore, regarding the upper limit of the temperature in the extruder, there is a slight difference in the characteristics of the regenerated resin between when using a regenerated resin obtained by decomposing a silane cross-linked resin with alcohol and when using a regenerated resin decomposed with a carbonic ester. Therefore, it is preferable to adjust by the recycled resin using the upper limit of the extruder internal temperature. When a regenerated resin obtained by decomposing a silane cross-linked resin with alcohol is used, the temperature is preferably set to 205 ° C. or lower. In the case of regenerated resin decomposed with carbonate ester, the molecular weight is somewhat smaller than that of alcohol decomposed regenerated resin, so it is difficult to re-form the cross-linking during re-crosslinking (the gel fraction is difficult to increase). It is preferable to raise the temperature of this to 210 ° C. or lower.

  In the present invention, depending on the extrusion conditions, there is no problem even if a crosslinking agent or a crosslinking catalyst is added to the recycled resin during extrusion molding, and the gel fraction immediately after extrusion molding is controlled to 1.0% or more and 20.5% or less. It is presumed that it can be done, but it is advantageous not to add it industrially because a new process is required.

  The gel fraction immediately after extrusion is 1.0% or more and 20.5% or less when a regenerated resin obtained by decomposing the silane cross-linked resin formed as described above with an alcohol or a carbonic ester is coated on a conductor or an electric wire core. To do.

  The reason why the gel fraction is 1.0% or more is to prevent cracking of the coating material and to withstand environmental stress cracks sufficiently. Here, the gel fraction is particularly controlled by the temperature. For example, the residence time in the extruder and the adjustment of moisture are considered to be effective for controlling the gel fraction.

  If the gel fraction immediately after extrusion is set higher than 20.5%, the extrusion moldability is deteriorated or the coating material is burnt.

  The covering material comprising the regenerated resin of the silane cross-linked resin of the present invention can be coated on a conductor and used as an insulating material, or coated on an electric wire core and used as a sheath.

  In any case, when the recycled resin is extrusion coated onto the conductor or the wire core, the gel fraction of the coating material immediately after extrusion is adjusted to 1.0% or more and 20.5% or less.

  When the regenerated resin is coated on the conductor and used as an insulating material, heat resistance is required. Therefore, it is preferable that the degree of crosslinking is further increased and the gel fraction is finally crosslinked to about 40% to 60%. In this case, if the regenerated resin is re-crosslinked so that the gel fraction immediately after extrusion is 1.0% or more and 20.5% or less on the conductor, and the extrusion-coated electric wire is allowed to stand for several days, the crosslinking proceeds further. Good.

  When the recycled resin is coated on the wire core and used as a sheath, it is necessary to further increase the degree of crosslinking after re-crosslinking so that the gel fraction immediately after extrusion is 1.0% or more and 20.5% or less. It can be used as it is. The sheath is required to prevent deterioration due to the use environment of the cable, and the coating material made of the recycled resin of the present invention exhibits an excellent effect particularly on environmental stress cracks.

  For the coating material comprising the regenerated resin of the silane cross-linked resin of the present invention, other additives can be used as appropriate within the range not exceeding the characteristics of the present invention.

  Next, examples of the present invention and comparative examples will be described.

  First, silane-crosslinked polyethylene was produced, and this was decomposed with alcohol or carbonate to obtain a recycled resin, and electric wires and cables were produced using this recycled resin.

Production of silane-crosslinked polyethylene:
First, the silane cross-linked resin used in this example and the comparative example is obtained by blending a linear low-density polyethylene with a cross-linking agent, an antioxidant, a stabilizer and a cross-linking catalyst shown in Table 1, and cross-linking with a siloxane bond. is there. Here, the gel fraction of the silane-crosslinked polyethylene after crosslinking was 55%.

Decomposition of silane cross-linked polyethylene:
This silane-crosslinked polyethylene resin was decomposed with methanol or dimethyl carbonate in a supercritical state under the conditions shown in Table 2 using a supercritical processing apparatus as shown in Patent Document 5.

Recycled resin:
Table 3 shows the characteristic values of the recycled resin obtained by the decomposition of the silane-crosslinked polyethylene.

Manufacture of electric wires and cables:
Using the above recycled resin, it was produced using a single screw extruder 1 having a diameter of 130 mm shown in FIGS.

1 and 2, pelletized recycled polyethylene is introduced from the hopper 2 of the extruder 1, the residence time in the extruder 1 is about 4 minutes 50 seconds, and the temperature of the cylinder of the extruder 1 is 180 ° C to The temperature was set to 215 ° C., and the copper plate (conductor nominal cross-sectional area 38 mm ² ) 8 was fed from the breaker plate 10 provided at the discharge port of the extruder 1 to the crosshead 3 through the neck 11 and from the feeder 4 to the crosshead. 3, drawn out from the die 12 so as to be 1.5 mm thick on the copper conductor 8, cooled in the cooling water tank 5, and wound up by the winder 7 through the take-up machine 6 and manufactured by the winder 7. did.

  When manufacturing the electric wires and cables, as shown in FIG. 2, the extruder 1 is divided into four cylinders in the extrusion discharge direction, and the temperatures of the cylinders 1 to 4 and the temperatures of the neck 11, the crosshead 3 and the die 12 are individually set. Controlled.

  In addition, the regenerated resin was subjected to experiments separately from those decomposed using methanol (Table 4) and those decomposed using dimethyl carbonate (Table 5).

  In Tables 4 and 5, the cases of Example 1 and Example 5 to which a crosslinking agent and a crosslinking catalyst were added were as follows.

  First, 0.94 parts by mass of a crosslinking agent was impregnated with 95 parts by mass of recycled polyethylene. As a crosslinking agent, 0.9 part by mass of vinyltrimethoxysilane as a silane compound and 0.04 part by mass of dicumyl peroxide as a radical generator were added.

  Next, a master batch was prepared by kneading 1 part by mass of dibutyltin dilaurate as a crosslinking catalyst with 100 parts by mass of recycled polyethylene. This master batch was mixed with 5 parts by mass of 95 parts by mass of recycled polyethylene impregnated with the above-mentioned crosslinking agent to obtain a recycled resin.

  Also, in Tables 4 and 5, the temperature control is such that the temperature of the cylinder 1 is 180 ° C., the temperature from the cylinder 2 to the cylinder 4 is increased in increments of 5 ° C. to 10 ° C., and the temperatures of the neck, crosshead and die are It was the same as the temperature of 4 or higher than the temperature of the cylinder 4.

  Working efficiency of the wire / cable coating material produced under the conditions of Examples and Comparative Examples shown in Tables 4 and 5, gel fraction of the coating material immediately after extrusion, wire / cable appearance (core appearance), environmental stress The crack properties were evaluated as follows.

Work efficiency:
In Examples 1 and 5 in which the crosslinking agent and the crosslinking catalyst were added as described above, the workability in the production was set as Δ, and the case where the crosslinking agent and the crosslinking catalyst were not added was marked as ◯.

Gel fraction immediately after extrusion:
The gel fraction is an index representing the degree of cross-linking of the resin. About 1 g of the coating material is placed in a wire mesh and extracted in hot xylene at 110 ° C. for 24 hours, and the portion remaining in the wire mesh (gel ) And the initial mass before extraction.
Gel fraction (%) = (mass of gel after drying (g) / initial mass (g)) × 100

  This gel fraction passed 1.0% or more and 20.5% or less.

Cable appearance (core appearance):
The external appearance of the electric wires / cables was visually observed, and those that were smooth were judged good, and those that were burned were judged defective.

Environmental stress crack properties:
The environmental stress crack characteristics basically conformed to JIS K6760 (constant strain environmental stress crack test).

  The covering material is punched with a punching blade having a width of 13 mm and a length of 38 mm so that the long axis of the test piece (38 mm) and the cable longitudinal direction are parallel to each other to produce a test piece (n = 10). A notch with a length of 19.1 mm and a depth of 0.25 mm was added (however, the thickness of the test piece is defined as 3 mm in JIS K6760, but the coating material of 1.5 mm was used as it was as a test piece. The notch depth was arbitrarily set). The test temperature was 50 ° C., and the test solution was Fge (the time when cracks occurred in a 50% sample) using a 10% aqueous solution of Igepearl.

  The determination of the environmental stress cracking property was accepted if it was equivalent to the base polyethylene before regeneration shown in Table 1 (F50> 2000 hours), and rejected if it was less than 2000 hours.

  These evaluation items were comprehensively judged to make ○, Δ, and ×, and ○ and Δ were regarded as acceptable.

Example 1:
From Table 4, it was confirmed in Example 1 that the appearance of the cable was sufficiently smooth. Moreover, the gel fraction of the coating material (recycled polyethylene) immediately after extrusion was 10.2%. In the environmental stress crack test, no cracks were observed even after 2000 hours (n = 10, all were not cracked). However, since the temperature in the extruder was lowered under these conditions, a crosslinking agent and a crosslinking catalyst were added to ensure sufficient re-crosslinking. Since a step of impregnating the crosslinking agent, a step of kneading the crosslinking catalyst, and a step of mixing these are required before cable extrusion, the working efficiency is slightly worse compared to Examples 2-4.

  From the above, there is no problem with the characteristics of the cable, but when compared with Examples 2 to 4, the manufacturing method is slightly inferior in terms of industrial production, so the determination is Δ.

Example 2:
From Table 4, in Example 2, it was confirmed that the appearance of the cable was sufficiently smooth. Moreover, the gel fraction of the coating material (recycled polyethylene) immediately after extrusion was 1.2%. In the environmental stress crack test, no cracks were observed even after 2000 hours (n = 10, all were not cracked). Under these conditions, a new process is not particularly required as an extrusion operation or a pre-extrusion operation. Based on the above, the evaluation was evaluated as ◯ because there was no problem in the characteristics of the electric wire / cable and the manufacturing method.

Example 3:
From Table 4, it was confirmed in Example 3 that the appearance of the cable was sufficiently smooth. Moreover, the gel fraction of the coating material (recycled polyethylene) immediately after extrusion was 4.8%. In the environmental stress crack test, no cracks were observed even after 2000 hours (n = 10, all were not cracked). Under these conditions, a new process is not particularly required as an extrusion operation or a pre-extrusion operation.

  Based on the above, the evaluation was evaluated as ◯ because there was no problem in the characteristics of the electric wire / cable and the manufacturing method.

Example 4:
From Table 4, it was confirmed in Example 4 that the appearance of the cable was sufficiently smooth. The gel fraction of the coating material (recycled polyethylene) immediately after extrusion was 20.1%. In the environmental stress crack test, no cracks were observed even after 2000 hours (n = 10, all were not cracked). Under these conditions, a new process is not particularly required as an extrusion operation or a pre-extrusion operation.

  From the above, the judgment was evaluated as ◯ because there was no problem in the cable characteristics and the manufacturing method.

Example 5:
From Table 5, it was confirmed in Example 5 that the appearance of the cable was sufficiently smooth. Moreover, the gel fraction of the coating material (recycled polyethylene) immediately after extrusion was 7.2%. In the environmental stress crack test, no cracks were observed even after 2000 hours (n = 10, all were not cracked). However, since the temperature in the extruder was lowered as in Example 1, a crosslinking agent and a crosslinking catalyst were added to ensure sufficient re-crosslinking. Under these conditions, a cross-linking agent impregnation step, a cross-linking catalyst kneading step, and a step of mixing these are required before cable extrusion, so that the working efficiency is slightly deteriorated as compared with Examples 6-8.

  From the above, there is no problem with the characteristics of the cable, but when compared with Examples 6 to 8, the manufacturing method is slightly inferior in industrial terms, so the determination is Δ.

Example 6:
From Table 5, it was confirmed in Example 6 that the appearance of the cable was sufficiently smooth. Moreover, the gel fraction of the coating material (recycled polyethylene) immediately after extrusion was 1.1%. In the environmental stress crack test, no cracks were observed even after 2000 hours (n = 10, all were not cracked). Under these conditions, a new process is not particularly required as an extrusion operation or a pre-extrusion operation.

  From the above, the judgment was evaluated as ◯ because there was no problem in the cable characteristics and the manufacturing method.

Example 7:
From Table 5, it was confirmed in Example 7 that the appearance of the cable was sufficiently smooth. Moreover, the gel fraction of the coating material (recycled polyethylene) immediately after extrusion was 15.1%. In the environmental stress crack test, no cracks were observed even after 2000 hours (n = 10, all were not cracked). Under these conditions, a new process is not particularly required as an extrusion operation or a pre-extrusion operation.

  From the above, the judgment was evaluated as ◯ because there was no problem in the cable characteristics and the manufacturing method.

Example 8:
From Table 5, it was confirmed in Example 8 that the appearance of the cable was sufficiently smooth. Moreover, the gel fraction of the coating material (recycled polyethylene) immediately after extrusion was 20.0%. In the environmental stress crack test, no cracks were observed even after 2000 hours (n = 10, all were not cracked). Under these conditions, a new process is not particularly required as an extrusion operation or a pre-extrusion operation.

  From the above, the judgment was evaluated as ◯ because there was no problem in the cable characteristics and the manufacturing method.

  From the results of Examples 1 to 8, it was found that the gel fraction increases by increasing the temperature from the temperature 180 ° C. of the cylinder 1 to the die 12 using the extrusion temperature as a parameter. In this case, if the gel fraction of the recycled polyethylene decomposed with methanol is 1.2 to 20.1% and the gel fraction of the recycled polyethylene decomposed with dimethyl carbonate is 1.1 to 20.0%, the cable It was found that a wire / cable coating material with a smooth appearance and excellent environmental stress crack resistance was obtained.

  A chemical reaction for forming a siloxane bond, which is a cross-linked bond, is a condensation reaction of an alkoxysilane or silanol group, and can be controlled by adjusting heat and moisture. In this example, the gel fraction was controlled only by the extrusion temperature, but the same control can be achieved by adjusting the residence time in the extruder to change the amount of heat given to the recycled polyethylene, or by adjusting the moisture content in the extruder. Is considered possible.

  In this method, there is no problem even if a crosslinking agent and a crosslinking catalyst are added to the recycled polyethylene as in Example 1 and Example 5. However, a new impregnation step for the crosslinking agent, a kneading step for the crosslinking catalyst, A mixing step is required. Although it is considered that there is no problem in producing a cable by adding a crosslinking agent and a crosslinking catalyst, Examples 2 to 4 and Examples 6 to 8, which are methods in which these are not added, are more industrial production methods. It can be said that there is.

Comparative Example 1:
From Table 4, in Comparative Example 1, although the extrusion molding temperature was lowered, the crosslinking agent and the crosslinking catalyst were not added as in Example 1, so that the re-crosslinking was not performed, and the gel fraction immediately after extrusion was 0. %Met. The appearance of the cable was sufficiently smooth. Further, under these conditions, a new process is not particularly required as an extrusion operation or a pre-extrusion operation.

  However, it has been found that the environmental stress cracking property F50 is 100 hours, and the property is remarkably reduced as compared with the base polyethylene before regeneration.

Comparative Example 2:
From Table 4, in Comparative Example 2, the gel fraction immediately after extrusion was 22.0%, and no crack was seen even after 2000 hours in the environmental stress crack test (n = 10, all cracks were not found), but the cable Burns occurred on the surface. This is because the gel fraction increased due to the increase in the extrusion temperature from the cylinder 4 to the die (200 ° C. → 210 ° C.) and the environmental stress cracking property was good, but the crosslinking reaction proceeded excessively in the extruder. , I think that burns occurred.

Comparative Example 3:
From Table 5, in Comparative Example 3, although the extrusion molding temperature was lowered, the crosslinking agent and the crosslinking catalyst were not added as in Example 5, so that the cross-linking was not performed and the gel fraction immediately after extrusion was 0. %, And the appearance of the cable was sufficiently smooth. Further, under these conditions, a new process is not particularly required as an extrusion operation or a pre-extrusion operation. However, it has been found that the environmental stress cracking property F50 is 90 hours, and the property is remarkably reduced as compared with the base polyethylene before regeneration.

Comparative Example 4:
From Table 5, in Comparative Example 4, the gel fraction immediately after extrusion was 20.9%, and no cracks were seen even after 2000 hours in the environmental stress crack test (n = 10, all cracks were not found), but the cable Burns occurred on the surface. This is because the gel fraction increased due to the increase in the extrusion temperature from the cylinder 4 to the die (200 ° C. → 215 ° C.) and the environmental stress cracking property was good, but the crosslinking reaction proceeded excessively in the extruder. , I think that burns occurred.

  From the above, (1) the gel fraction immediately after extrusion is 0%, the environmental stress cracking properties are significantly lower than the base polyethylene before regeneration, and (2) the gel immediately after extrusion by raising the extrusion temperature. It was found that if the fraction was increased excessively, the crosslinking reaction proceeded in the extruder and burns occurred.

  Accordingly, the extrusion temperature is 180 ° C. at the time of charging, and the recycled resin decomposed with alcohol has a gel fraction of 1.2 to 1.2 ° C. if the temperature of the die portion that is the highest temperature is increased to 190 ° C. or more and 205 ° C. or less. If the temperature of the recycled resin decomposed with carbonate ester is controlled to 20.1% or more and 190 ° C or more and 210 ° C or less, the gel fraction can be controlled to 1.1 to 20.0%. A fraction can be made into 1.0 or more and 20.5% or less, and it can be set as the coating material excellent in the environmental stress cracking resistance.

  By using the present invention as described above, a regenerated resin obtained by decomposition treatment with alcohol or carbonate using a silane cross-linked resin as a raw material is formed in the outermost layer of an electric wire / cable so that it has excellent environmental stress crack resistance and appearance. It can be applied as a good coating material for electric wires and cables. Since this regenerated resin is silane-grafted, it is possible to adjust the gel fraction by simply controlling the extrusion conditions without adding a cross-linking agent or cross-linking catalyst, increasing the cost of new additives. Does not occur. Of course, not only is it economical, but it can also be said to have great environmental effects because recycled materials can be applied directly to wire and cable coating materials.

1 Single screw extruder 2 Hopper 3 Crosshead 8 Conductor 9 Electric wire / cable

Claims (8)

  In a method for manufacturing an electric wire / cable using a regenerated resin obtained by decomposing a cross-linked portion of a silane cross-linked resin with an alcohol or a carbonic ester, a gel of a coating material immediately after the regenerated resin is extruded onto a conductor or an electric wire core A method for producing an electric wire / cable using a recycled resin, wherein the extrusion is performed so that the fraction is 1.0% or more and 20.5% or less.   Extrusion so that the gel fraction of the recycled resin is 0%, and the gel fraction of the coating material immediately after extrusion of the recycled resin onto a conductor or electric wire core is 1.0% to 20.5% The method for producing an electric wire / cable using the recycled resin according to claim 1, wherein an extrusion temperature at the time of formation is adjusted.   A cross-linking agent and a cross-linking catalyst are added to the regenerated resin at the time of forming the extrusion, the extrusion temperature in the extruder is adjusted, and the gel fraction of the coating material immediately after extruding the regenerated resin onto a conductor or electric wire core is 1.0. The method for producing an electric wire / cable using the recycled resin according to claim 1 or 2, wherein the ratio is from 2% to 20.5%.   The recycled resin obtained by decomposing the crosslinked part of the silane crosslinked resin with alcohol has an extruder internal temperature of 160 ° C. or higher and 205 ° C. or lower, and the die part temperature that is the highest inside the extruder is 180 ° C. or higher and 205 ° C. The method for producing an electric wire / cable using the recycled resin according to any one of claims 1 to 3, wherein the extrusion is formed by controlling the following.   The recycled resin obtained by decomposing the cross-linked portion of the silane cross-linked resin with a carbonate ester has an extruder internal temperature of 160 ° C. or higher and 210 ° C. or lower, and the die portion temperature that is the highest inside the extruder is 180 ° C. or higher and 210 ° C. The method for producing an electric wire / cable using the recycled resin according to any one of claims 1 to 3, wherein the extrusion molding is carried out by controlling the temperature to not higher than ° C.   A crosslinking agent and a crosslinking catalyst are not added to the regenerated resin at the time of the extrusion formation, the extrusion temperature in the extruder is adjusted, and the gel fraction of the coating material immediately after extruding the regenerated resin onto a conductor or a wire core is 1.0. The method for producing an electric wire / cable using the recycled resin according to claim 1 or 2, wherein the ratio is from 2% to 20.5%.   Recycled resin obtained by decomposing the cross-linked part of the silane cross-linked resin with alcohol has an extruder internal temperature of 180 ° C. or higher and 205 ° C. or lower, and the die part temperature that is the highest inside the extruder is 190 ° C. or higher and 205 ° C. The method for producing an electric wire / cable using the recycled resin according to any one of claims 1, 2, and 6, wherein the extrusion is controlled as follows.   The recycled resin obtained by decomposing the cross-linked portion of the silane cross-linked resin with a carbonate ester has an extruder internal temperature of 180 ° C. or higher and 210 ° C. or lower, and the temperature of the die portion that is the highest temperature inside the extruder is 190 ° C. or higher and 210 ° C. The method for producing an electric wire / cable using the regenerated resin according to any one of claims 1, 2, and 6, wherein the extrusion forming is performed by controlling the temperature to be equal to or lower than ° C.