CN111704780A

CN111704780A - Electric wire and cable

Info

Publication number: CN111704780A
Application number: CN202010499276.4A
Authority: CN
Inventors: 芦原新吾; 青山贵; 矢崎浩贵
Original assignee: Hitachi Metals Ltd
Current assignee: Proterial Ltd
Priority date: 2015-07-27
Filing date: 2016-06-17
Publication date: 2020-09-25
Also published as: JP6549928B2; WO2017018091A1; JP2017027887A; CN107924737A

Abstract

An electric wire and cable according to one embodiment of the present invention includes a conductor and a coating layer for coating an outer periphery of the conductor, the coating layer being formed by crosslinking a silane crosslinkable composition containing a silane-grafted chlorinated polyethylene obtained by graft-copolymerizing a silane compound and a chlorinated polyethylene, and a non-mineral oil plasticizer.

Description

Electric wire and cable

The present application is a divisional application filed on 2016, 17.06.32, 201680044052.6, entitled "wire and cable".

Technical Field

The invention relates to a wire cable.

Background

Chlorinated polyethylene is a thermoplastic elastomer excellent in various properties such as heat resistance and abrasion resistance, and has been used as a material for forming a coating layer (for example, an insulating layer, a sheath, or the like) for coating the outer periphery of a conductor in an electric wire such as an electric wire and a cable.

Generally, when the coating layer is formed using chlorinated polyethylene, a crosslinking treatment is performed to improve the oil resistance of the coating layer. As the crosslinking treatment, for example, silane crosslinking using a silane compound (so-called silane coupling agent) is widely performed (for example, see patent document 1). Specifically, when silane crosslinking is performed on chlorinated polyethylene to form a coating layer, first, a silane compound is mixed with the chlorinated polyethylene and kneaded. Subsequently, a silane compound and chlorinated polyethylene are graft-copolymerized by heating to form a silane crosslinkable composition containing silane-grafted chlorinated polyethylene. Next, the silane crosslinkable composition is extruded so as to cover the outer periphery of the conductor and molded into a predetermined shape. Thereafter, the molded article is brought into contact with moisture to cause a crosslinking reaction, thereby forming a silane-crosslinked coating layer.

Documents of the prior art

Patent document

Patent document 1: japanese examined patent publication (Kokoku) No. 50-35540

Disclosure of Invention

Various additives are blended in the silane crosslinkable composition forming the coating layer according to the properties required for the coating layer. For example, various additives such as a plasticizer for imparting flexibility to the coating layer, a stabilizer for imparting resistance to the external environment, carbon black for imparting abrasion resistance, and the like are blended. From the viewpoint of simplifying the production process, these additives are generally blended simultaneously when the silane compound is blended with the chlorinated polyethylene. Then, they are kneaded and heated to graft-copolymerize a silane compound with chlorinated polyethylene in the presence of an additive.

However, when a silane compound is graft-copolymerized with chlorinated polyethylene in the presence of a plasticizer in the additive, the graft copolymerization may be inhibited by the plasticizer. As a result, in the silane-grafted chlorinated polyethylene, the ratio of graft copolymerization of the silane compound (hereinafter, also referred to as graft ratio) may be low, and a sufficient degree of crosslinking may not be obtained when the silane crosslinking is finally performed.

On the other hand, it is also conceivable to add a plasticizer which adversely affects the graft copolymerization after the graft copolymerization is performed, but since the graft copolymerization is performed at a relatively high temperature, when the plasticizer is added to the silane crosslinkable composition heated to a high temperature, the plasticizer may volatilize. Further, since it takes time to disperse the plasticizer in the silane crosslinkable composition, early crosslinking occurs, and it is difficult to extrude the silane crosslinkable composition to form a coating layer.

When the plasticizer is not blended, the coating layer formed has a sufficient degree of crosslinking, but has a low elongation, and the flexibility required for the coating layer cannot be satisfied.

The invention aims to provide an electric wire and a cable with a coating layer which has high crosslinking degree and excellent flexibility.

An electric wire cable according to one embodiment of the present invention includes a conductor and a coating layer for coating an outer periphery of the conductor,

the coating layer is formed by crosslinking a silane crosslinkable composition,

the silane crosslinkable composition contains a silane-grafted chlorinated polyethylene obtained by graft copolymerization of a silane compound and a chlorinated polyethylene, and a non-mineral oil plasticizer.

According to one aspect of the present invention, there is provided an electric wire and cable provided with a coating layer having a high degree of crosslinking and excellent flexibility.

Drawings

Fig. 1 is a cross-sectional view showing a schematic structure of a cable according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a grafting treatment using a single-screw extruder in examples.

Fig. 3 is an explanatory diagram illustrating the production of the cable in the embodiment.

Detailed Description

As described above, when a plasticizer is blended as an additive, graft copolymerization of a silane compound is inhibited, and therefore, a sufficient degree of crosslinking may not be obtained in the case of silane crosslinking. The plasticizer is generally an additive for improving the flexibility of the coating layer, and for example, mineral oil purified from crude oil is used. In the mineral oil, paraffin-based oil, naphthene-based oil, aromatic-based oil, and the like are present in accordance with the content ratio of each of paraffin, naphthene, and aromatic components. However, according to the studies of the present inventors, it is found that these mineral oils seriously inhibit the graft copolymerization of the silane compound even among the plasticizers, and therefore a sufficient degree of crosslinking is not obtained at the time of silane crosslinking.

Therefore, the present inventors have conducted studies using a non-mineral oil plasticizer instead of a mineral oil plasticizer, and as a result, it has been possible to increase the graft ratio to chlorinated polyethylene without inhibiting the graft copolymerization of a silane compound by using a non-mineral oil plasticizer such as chlorinated paraffin or a phthalate plasticizer. This makes it possible to obtain a high degree of crosslinking in the case of silane crosslinking. Further, since the non-mineral oil plasticizer is also excellent in compatibility with the silane-grafted chlorinated polyethylene, it is less likely to be eluted from the coating layer, and bleeding can be suppressed. Therefore, a coating layer having a high degree of crosslinking and excellent flexibility can be formed by using a non-mineral oil plasticizer.

The present invention has been completed based on the above findings.

< one embodiment of the present invention >

Hereinafter, one embodiment of the present invention will be described.

(1) Silane crosslinkable composition

First, a silane crosslinkable composition for forming a coating layer of an electric wire and cable will be described.

The silane crosslinkable composition contains a silane-grafted chlorinated polyethylene and a non-mineral oil plasticizer.

The silane-grafted chlorinated polyethylene is obtained by mixing chlorinated polyethylene, a silane compound and a peroxide, and graft-copolymerizing the silane compound and the chlorinated polyethylene in the presence of the peroxide. The silane grafted chlorinated polyethylene consists of: the silane compound has a silane group derived from a graft-copolymerized silane compound in its molecular structure, and when the silane compound comes into contact with water, the silane group in the molecular structure is hydrolyzed to form silanol groups, and the silanol groups are dehydrated and condensed with each other to form a crosslinked structure, whereby silane crosslinking is performed.

Chlorinated polyethylene is a component having a structure in which hydrogen atoms in a hydrocarbon skeleton such as polyethylene are partially substituted with chlorine atoms having a large electronegativity, and having a large polarity. The chlorinated polyethylene is obtained by blowing chlorine gas into an aqueous suspension in which linear polyethylene (low density polyethylene, high density polyethylene, or the like) is suspended and dispersed in water, for example. The chlorinated polyethylene preferably has a degree of chlorination of 25% to 45% from the viewpoint of obtaining various properties of the coating layer such as heat resistance, oil resistance, and flame retardancy in a well-balanced manner, and more preferably 30% to 40% from the viewpoint of improving processability in forming the coating layer.

The silane compound has an unsaturated bond group and a hydrolyzable silane group. The silane compound introduces a silane group into the chlorinated polyethylene by graft copolymerization of an unsaturated bonding group with the chlorinated polyethylene.

The unsaturated group of the silane compound is not limited as long as the silane compound can be graft-copolymerized with chlorinated polyethylene, and examples thereof include a vinyl group, a methacryloyl group, and an acryloyl group. Among these, methacryloyl groups are preferable as the unsaturated bonding groups. The methacryl silane compound having a methacryl group has excellent compatibility with chlorinated polyethylene and is easily dispersed in chlorinated polyethylene, compared to a vinyl silane compound having a vinyl group, and therefore, can be uniformly graft-copolymerized with chlorinated polyethylene to form a uniform crosslinked structure. Further, compared with the vinylsilane compound, the flammability is low and the workability is excellent.

Examples of the hydrolyzable silane group of the silane compound include silane groups having a hydrolyzable structure such as halogen, alkoxy, acyloxy, and phenoxy. Examples of the silyl group having such a hydrolyzable structure include a halogenated silyl group, an alkoxysilyl group, an acyloxysilyl group, and a phenoxysilyl group.

Specific examples of the silane compound include methacryloylsilanes such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane.

The amount of the silane compound graft-copolymerized with the chlorinated polyethylene, that is, the amount of the silane compound to be blended in the chlorinated polyethylene may be appropriately changed depending on the degree of crosslinking of the final molded article (coating layer) or the reaction conditions (for example, temperature, time, etc.) at the time of crosslinking. Specifically, the amount of the silane compound is preferably 0.1 to 10 parts by mass, and more preferably 1.0 to 5.0 parts by mass, based on 100 parts by mass of the chlorinated polyethylene. By using such a blending amount, an appropriate degree of crosslinking can be obtained at the time of silane crosslinking.

The peroxide is used for graft copolymerization of the silane compound and the chlorinated polyethylene. Specifically, the peroxide generates oxygen radicals by thermal decomposition. The oxygen radicals generate radicals of the chlorinated polyethylene by removing hydrogen from the chlorinated polyethylene. Then, the silane compound and the chlorinated polyethylene are graft-copolymerized by reacting the radical of the chlorinated polyethylene with an unsaturated bond group (for example, a vinyl group, a methacryloyl group, or the like) of the silane compound. Thus, the peroxide generates oxygen radicals to produce graft copolymerization of the silane compound and the chlorinated polyethylene.

As the peroxide, for example, an organic peroxide can be used. The organic peroxide has high dehydrogenation ability to dehydrochlorinate chlorinated polyethylene, and can generate oxygen free radicals by thermal decomposition at a temperature at which chlorinated polyethylene is not easily degraded (not easily dehydrochlorinate). Since the deterioration starting temperature of chlorinated polyethylene is about 200 ℃, it is preferable to use an organic peroxide having a 1-minute half-life temperature of 120 to 200 ℃ as the peroxide. From the viewpoint of shortening the time required for the graft reaction, it is more preferable to use an organic peroxide having a 1-minute half-life temperature of 150 to 200 ℃. The 1-minute half-life temperature refers to a temperature at which the peroxide half-life is 1 minute.

Specifically, as the peroxide, dicumyl peroxide, 1-di (t-butylperoxy) cyclohexane, t-butylperoxyisopropyl carbonate, t-amylperoxyisopropyl carbonate, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, di-t-butylperoxide, di-t-amylperoxide, 1-di (t-amylperoxy) cyclohexane, 2-ethylhexyl t-butylperoxycarbonate, and the like can be used. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds. Of these, dicumyl peroxide having a 1 minute half-life temperature of about 175 ℃ may be used.

The amount of the peroxide to be blended may be appropriately changed depending on the amount of the silane compound to be blended, and is preferably 0.03 to 3.0 parts by mass per 100 parts by mass of the chlorinated polyethylene. By having such a blending amount, an appropriate degree of crosslinking can be obtained at the time of silane crosslinking.

In order to improve the flexibility of the coating layer, a plasticizer is blended in the silane crosslinkable composition, but in the present embodiment, as described above, a non-mineral oil plasticizer is used from the viewpoint of reacting the silane compound so as to increase the graft ratio. The plasticizer does not seriously inhibit the graft copolymerization of the silane compound and the chlorinated polyethylene, so that the grafting ratio of the silane compound can be improved. Further, since the silane-grafted chlorinated polyethylene is excellent in compatibility, it is less likely to bleed out from the silane-crosslinkable composition.

The non-mineral oil plasticizer is not particularly limited as long as it has a functional group having a large atom of electronegativity and a large polarity, and at least 1 of chlorinated paraffin and phthalate plasticizers is preferably used.

The chlorinated paraffin has the same chemical structure as chlorinated polyethylene, and is included in a crosslinked material when silane-grafted chlorinated polyethylene is subjected to silane crosslinking, whereby the degree of crosslinking, the oil resistance of the crosslinked material, and the like can be improved.

The phthalate plasticizer has an ester group and has a higher polarity than the mineral oil plasticizer, and therefore, the oil resistance of the crosslinked material can be improved.

From the viewpoint of further improving the crosslinking degree of the coating layer, chlorinated polyolefins which can be included in the crosslinked product are more preferable.

The amount of the non-mineral oil plasticizer to be blended is preferably 1 to 30 parts by mass per 100 parts by mass of the chlorinated polyethylene. With such a blending amount, the flexibility of the coating layer can be maintained high and the bleeding out from the coating layer can be suppressed.

In addition, additives other than the plasticizer may be added to the silane crosslinkable composition. As further additives, for example, silanol condensation catalysts which promote silane crosslinking can be used. Examples of the silanol condensing catalyst include group II elements such as magnesium and calcium, group VIII elements such as cobalt and iron, metallic elements such as tin, zinc and titanium, and metallic compounds containing these elements. Further, metal salts of octanoic acid and adipic acid, amine compounds, acids, and the like can be used. Specifically, metal salts such as dioctyldineodecanoyloxytin, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octoate, lead naphthenate, zinc octoate, and cobalt naphthenate, amine compounds such as ethylamine, dibutylamine, hexylamine, and pyridine, inorganic acids such as sulfuric acid and hydrochloric acid, and organic acids such as toluenesulfonic acid, acetic acid, stearic acid, and maleic acid can be used.

Further, as other additives, antioxidants (including age resistors), fillers such as carbon black, flame retardants, lubricants, copper discoloration inhibitors, crosslinking aids, stabilizers, and the like can be used.

(2) Method for producing silane crosslinkable composition

Next, a method for producing the silane crosslinkable composition will be described.

First, a non-mineral oil plasticizer was added to chlorinated polyethylene, and kneading was performed. The non-mineral oil plasticizer has compatibility with the chlorinated polyethylene, and therefore can disperse the plasticizer into the chlorinated polyethylene. The non-mineral oil plasticizer is preferably blended in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the chlorinated polyethylene. When the plasticizer is added, other additives such as an antioxidant and carbon black may be added.

Next, a silane compound and a peroxide are added to a mixture in which a plasticizer is dispersed in chlorinated polyethylene, and kneading is performed. Since the non-mineral oil plasticizer having compatibility with the silane compound is dispersed in the mixture, the silane compound can be uniformly dispersed in the mixture without coagulating. The silane compound is preferably blended in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the chlorinated polyethylene, and the peroxide is preferably blended in the range of 0.03 to 3.0 parts by mass with respect to 100 parts by mass of the chlorinated polyethylene.

Next, the mixture to which the silane compound and the peroxide are added is heated and kneaded, thereby graft-copolymerizing the silane compound and the chlorinated polyethylene in the presence of the peroxide. Thus, a silane-grafted chlorinated polyethylene was formed, and a silane-crosslinkable composition comprising the silane-grafted chlorinated polyethylene and a non-mineral oil plasticizer was obtained. In the present embodiment, since the silane compound is uniformly dispersed in the chlorinated polyethylene without being coagulated and then graft-copolymerized, the silane compound has a high graft ratio to the silane-grafted chlorinated polyethylene and silane groups are uniformly introduced. Further, since the non-mineral oil plasticizer has compatibility with the silane-grafted chlorinated polyethylene, bleeding is suppressed.

In the case of kneading the mixture, for example, kneading may be performed using a kneading reaction apparatus such as a roll mill, an extruder, a kneader, a mixer, or an autoclave. The kneading conditions and the grafting reaction conditions (temperature, time, etc.) are not particularly limited.

(3) Silane crosslinked material

The silane-crosslinked material is obtained by bringing the silane-crosslinkable composition described above into contact with water to crosslink the silane-grafted chlorinated polyethylene with silane. In the present embodiment, since the silane-grafted chlorinated polyethylene has a high grafting ratio and silane groups are uniformly introduced into the chemical structure, the silane-crosslinked product obtained therefrom has a high degree of crosslinking and forms a crosslinked structure homogeneously.

The crosslinked silane product has a high degree of crosslinking, and the gel fraction as an index of the degree of crosslinking is 70% or more. If the gel fraction is less than 70%, the degree of crosslinking of the silane crosslinked material is low, and therefore, for example, when the crosslinked material is formed as a coating layer of an electric wire or cable, sufficient mechanical properties cannot be obtained. The upper limit of the gel fraction is not particularly limited, and as the gel fraction increases, the crosslinked structure is formed more in the silane-crosslinked product, and the mechanical properties thereof are improved.

The gel fraction was determined as follows. First, a sample formed of a silane crosslinked material was immersed in xylene, and the xylene was heated to boil. Thereafter, the sample remaining without being dissolved in xylene (sample extracted with hot xylene) was taken out and dried, and the mass of the sample extracted with hot xylene was measured. Then, the gel fraction of the silane-crosslinked product was determined by calculating the ratio of the mass of the sample after extraction with hot xylene to the mass of the sample before extraction with hot xylene. The gel fraction R is represented by the following formula, where a represents the mass of the sample before extraction with hot xylene and b represents the mass of the sample after extraction with hot xylene.

R(％)＝(b/a)×100

Further, the silane-crosslinked material contains a non-mineral oil plasticizer. Therefore, the silane crosslinked product is easily stretched and has excellent flexibility. Moreover, the compatibility of the plasticizer is high, and therefore, the bleeding of the plasticizer is suppressed.

(4) Electric wire and cable

Next, an electric wire cable according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a case of a cable having a sheath as a coating layer will be described as an example. Fig. 1 is a cross-sectional view showing a schematic structure of a cable according to an embodiment of the present invention.

As shown in fig. 1, the cable 1 of the present embodiment includes a conductor 10. As the conductor 10, a copper wire, a copper alloy wire, a metal wire, or a twisted wire obtained by twisting metal wires, the copper wire being made of low-oxygen copper, oxygen-free copper, or the like, or the metal wire being made of aluminum, silver, or the like, may be used. The outer diameter of the conductor 10 may be appropriately changed according to the use of the cable 1.

An insulating layer 11 is provided to cover the outer periphery of the conductor 10. The insulating layer 11 is formed of a conventionally known resin composition, for example, a resin composition containing ethylene propylene rubber. The thickness of the insulating layer 11 may be appropriately changed according to the use of the cable 1.

A coating layer 12 (jacket 12) is provided so as to cover the outer periphery of the insulating layer 11. The sheath 12 is formed of a silane crosslinked material crosslinked with a silane crosslinkable composition. The sheath 12 has a high degree of crosslinking and is constituted so that the gel fraction is 70% or more.

The cable 1 is manufactured, for example, as follows.

First, for example, a copper wire is prepared as the conductor 10. Next, a resin composition containing an ethylene-propylene rubber is extruded by an extruder so as to cover the outer periphery of the conductor 10, thereby forming the insulating layer 11 having a predetermined thickness. Next, the silane crosslinkable composition is extruded to a predetermined thickness so as to cover the outer periphery of the insulating layer 11, thereby forming the sheath 12. Thereafter, the sheath 12 is exposed to an environment of, for example, 80 degrees in temperature and 90% in relative humidity to react with moisture, thereby silane-crosslinking the silane-crosslinkable composition forming the sheath 12.

< Another embodiment of the present invention >

While one embodiment of the present invention has been specifically described above, the present invention is not limited to the above embodiment, and can be modified as appropriate within a range not departing from the gist thereof.

In the above-described embodiment, the cable 1 was described as an example of the electric wire cable, but the present invention is not limited to this, and may be configured as an insulated wire having an insulating layer as a coating layer. In this case, as in the case of forming the sheath 12 in the above-described embodiment, the silane crosslinkable composition may be extruded to the outer periphery of the conductor to form the insulating layer, and the insulating layer may be brought into contact with water to be silane-crosslinked.

In the above-described embodiment, the case where the cable 1 includes 1 wire having an insulating layer provided on the outer periphery of a conductor has been described, but the cable 1 may include twisted wires obtained by twisting 2 or more wires.

Examples

Next, an embodiment of the present invention will be explained.

The materials used in the examples and comparative examples are as follows.

Chlorinated polyethylene (Mooney viscosity at 121 ℃ (ML1+ 4): 55, heat of fusion: less than 1.0J/g): "CM 352L" made by Hangzhou Keli chemical Co., Ltd "

Hydrotalcite: MAGCELER 1, PRODUCED BY JUNCTION CHEMICAL INDUSTRIAL CO., LTD "

Epoxidized soybean oil: "Newcizer 510R" manufactured by Nippon fat and oil Co., Ltd "

Peroxide (dicumyl peroxide): "DCP" manufactured by Nippon fat and oil Co., Ltd "

Silane compound (3-methacryloxypropyltrimethoxysilane): KBM-503, manufactured by shin-Etsu chemical industries, Ltd "

Silane compound (3-methacryloxypropyltriethoxysilane): KBE-503, manufactured by shin-Etsu chemical industries, Ltd "

Plasticizer (chlorinated paraffin): "EMPARA 40" manufactured by Ajinomoto Fine-Techno Kabushiki Kaisha "

Plasticizer (di-2-ethylhexyl phthalate): new Nissan chemical and physical Co., Ltd, "SANSO CIZER DOP"

Plasticizer (diisononyl phthalate): new Nissan physicochemical Co., Ltd, "SANSO CIZER DINP"

Plasticizer (paraffin process oil, carbon atom ratio in the component; paraffin/naphthene/aromatic 68/28/4): japan Sun Oil Co., Ltd. "SUNPAR 115"

Plasticizer (naphthenic process oil, carbon atom ratio in the component; paraffin/naphthene/aromatic 49/35.5/15.5): NP-24 from "Qiongsheng" Kabushiki Kaisha "

Plasticizer (aromatic process oil, carbon atom ratio in the component; paraffin/naphthene/aromatic 20/32/48): fuji Kshixing Kabushiki Kaisha 'AROMAX # 1'

Flame retardant (antimony trioxide): antimony trioxide manufactured by Sumitomo Metal mining Co Ltd "

Carbon (FEF carbon black): "Asahi Carbon 60G" manufactured by Asahi Carbon corporation "

Lubricant (polyethylene wax (PE wax, molecular weight: 2800)): HI-WAX NL-200 manufactured by Mitsui chemical Co., Ltd "

Lubricant (ethylene bis-oleamide): "SLPACKS-O" manufactured by Nippon Kabushiki Kaisha "

Phenol-based antioxidant (4, 4' -thiobis (3-methyl-6-tert-butylphenol)): NORAC 300R manufactured by Dai-Innovation chemical industry Co., Ltd "

Amine antioxidant (2,2, 4-trimethyl-1, 2-dihydroquinoline polymer): NORAC 224 from Dai-Innovation chemical industry Co., Ltd "

Silanol condensation catalyst (dioctyldineodecanoyloxytin): "NEOSTANN U-830" manufactured by NIUDONG CHEMICAL CORPORATION "

(1) Preparation of silane crosslinkable composition

< example 1 >

First, additives such as a plasticizer are added to a base polymer.

Specifically, as shown in table 1 below, 100 parts by mass of chlorinated polyethylene, 6 parts by mass of hydrotalcite as a stabilizer, 6 parts by mass of epoxidized soybean oil as a stabilizer, 3 parts by mass of PE wax as a lubricant, 1 part by mass of ethylenebisoleamide as a lubricant, 40 parts by mass of carbon, and 10 parts by mass of non-mineral oil-based chlorinated paraffin as a plasticizer were put into a pressure kneader and kneaded at a blade rotation speed of 20rpm for 5 minutes. In this case, the kneading tank is not particularly heated, and the temperature of the kneaded product is raised to about 100 ℃ by heat release of the rubber component.

Subsequently, a silane compound and a peroxide are added to the kneaded mixture.

0.5 part by mass of dicumyl peroxide as a peroxide was dissolved in 3.35 parts by mass of 3-methacryloxypropyltrimethoxysilane as a silane compound to obtain a silane mixture, and the silane mixture was charged into the above-mentioned pressure kneader and further kneaded at a blade rotation speed of 20rpm for 5 minutes. The temperature of the kneaded mixture after kneading was about 110 ℃.

Subsequently, the kneaded mixture was subjected to a silane grafting treatment using a single-screw extruder 100 shown in fig. 2.

Specifically, the kneaded material is continuously supplied from the hopper 101 of the single-screw extruder 100 into the cylinder 103a, and is discharged from the cylinder 103a into the cylinder 103b by the rotation of the screw 102. At this time, the kneaded mixture is heated in the

cylinders

103a and 103b to soften and knead, and thereby the silane compound and the chlorinated polyethylene are graft-copolymerized. Thus, a silane-grafted chlorinated polyethylene was formed, and a silane-crosslinkable composition containing the silane-grafted chlorinated polyethylene was obtained. Thereafter, the silane crosslinkable composition was fed to the head 104 of the extruder 100, and the strand 20 (length 150cm) of the silane crosslinkable composition was extruded from the die 105. Then, the wire harness 20 is introduced into a water tank 106 and water-cooled, and moisture is removed by an air wiper 107. Thereafter, the strand 20 was granulated by the granulator 108 to form a pellet 21 made of the silane crosslinkable composition. Then, in order to prevent the pellets 21 from sticking to each other, 1 part by mass of talc was scattered over the pellets 21 to obtain a composite of example 1.

In the silane grafting treatment, a 40mm uniaxial extruder 100 was used. Further, the ratio L/D of the screw diameter D to the screw length L was set to 25. The temperature of the cylinder 103a was set to 80 ℃, the temperature of the cylinder 103b was set to 200 ℃, and the temperature of the head 104 was set to 200 ℃. In addition, a screw 102 having a full flight shape and a compression ratio of 2.0 was used. The rotation speed of the screw 102 was 20 rpm. Further, as the die 105, a die having a hole diameter of 5mm and 3 holes was used.

Next, in addition to the above compound, a master batch containing an antioxidant and a silanol condensing catalyst was additionally prepared.

Specifically, 100 parts by mass of chlorinated polyethylene, 6 parts by mass of hydrotalcite as a stabilizer, 6 parts by mass of epoxidized soybean oil as a stabilizer, 0.08 part by mass of a phenol-based antioxidant, 1.5 parts by mass of an amine-based antioxidant and 2 parts by mass of a silanol condensation catalyst were put into a pressure type kneader and kneaded at a blade rotation speed of 20rpm for 10 minutes. Then, the kneaded mixture was continuously fed to a single-screw extruder 100 shown in fig. 2, kneaded under the same conditions as described above, extruded into a strand shape, and pelletized, thereby obtaining pellets of a master batch. In the pressure kneader, the temperature of the kneaded mixture was raised to 100 ℃ by heat release of the rubber component.

Finally, a pellet-like master batch was added to the pellet-like composite, and dry blending was performed, thereby preparing the silane crosslinkable composition of example 1. At this time, the master batch was added to the composite in a proportion of 2.5 parts by mass relative to 100 parts by mass of the chlorinated polyethylene in the composite.

[ Table 1]

< examples 2 and 3 >

In examples 2 and 3, a silane crosslinkable composition was prepared and a cable was produced in the same manner as in example 1 except that the kind of the plasticizer contained in the silane crosslinkable composition was changed from chlorinated paraffin to di-2-ethylhexyl phthalate or diisononyl phthalate as shown in table 1.

< example 4 >

A silane crosslinkable composition was prepared and a cable was produced in the same manner as in example 1 except that in example 4, the type of silane compound was changed from 3-methacryloxypropyltrimethoxysilane to 3-methacryloxypropyltriethoxysilane, and the amount of silane compound added was changed from 3.35 parts by mass to 3.92 parts by mass.

< comparative example 1 >

A silane crosslinkable composition was prepared and a cable was produced in the same manner as in example 1, except that the plasticizer was not added to comparative example 1.

< comparative examples 2 to 4 >

In comparative examples 2 to 4, a silane crosslinkable composition was prepared and a cable was produced in the same manner as in example 1, except that the type of the plasticizer was changed from a non-mineral oil type plasticizer to a mineral oil type plasticizer. As the mineral oil-based plasticizer, paraffin-based process oil was used in comparative example 2, naphthene-based process oil was used in comparative example 3, and aromatic-based process oil was used in comparative example 4.

(2) Manufacture of electric cables

Next, the prepared silane crosslinkable composition was extruded by the single-screw extruder 100 shown in fig. 3, thereby producing the cables 1 of examples 1 to 4 and comparative examples 1 to 4. Specifically, the conductor 10 having a cross-sectional area of 8mm was inserted into the die 105 of the single-screw extruder 100²The cable 1 was produced by extruding ethylene propylene rubber (EP rubber) to the outer periphery thereof to form an insulating layer 11 having a thickness of 1.0mm, and extruding the silane crosslinkable composition to the outer periphery of the insulating layer 11 to form a sheath 12 having a thickness of 1.7 mm. The cable 1 was then placed at a temperature of 60 deg.CAnd keeping the mixture in a constant-temperature constant-humidity tank with the relative humidity of 95% for 24 hours, and performing silane crosslinking treatment.

In the production of the cable 1, a 20mm single-shaft extruder 100 was used. Further, the ratio L/D of the screw diameter D to the screw length L was set to 15. The cylinder 103a was set to 120 ℃, the cylinder 103b was set to 150 ℃, the crosshead 110 was set to 150 ℃, the neck 109 was set to 150 ℃, and the die 105 was set to 130 ℃. The rotation speed of the screw 102 was set to 15rpm, and a screw having a full flight shape and a compression ratio of 2.0 was used as the screw 102.

(3) Evaluation method

The cable thus produced was evaluated in the following manner.

(presence or absence of bleeding)

The surface appearance of the cable was visually observed for the presence or absence of bleeding, and the cable was evaluated as "good" if no plasticizer was bled, and as "bad" if bleeding was observed.

(gel fraction after crosslinking)

In order to evaluate the degree of crosslinking of the sheath, the gel fraction of the sheath after silane crosslinking was measured.

First, 0.5g of a sample was collected from the silane-crosslinked sheath and placed in a 40-mesh brass metal mesh. Subsequently, the sample was subjected to extraction treatment with xylene in an oil bath at 110 ℃. After the extraction treatment, the remaining sample was taken out of the xylene and dried under vacuum at 80 ℃ for 4 hours. Then, the mass of the sample remaining after drying was weighed, and the gel fraction R of the sample was calculated from the mass a of the sample before xylene extraction and the mass b of the sample remaining after xylene extraction by the following formula.

R(％)＝b/a×100

In this example, the gel fraction after crosslinking was 70% or more and evaluated as "good", and the gel fraction below 70% was evaluated as "poor".

(tensile elongation)

To evaluate the flexibility of the sheath, the tensile elongation of the sheath was measured.

First, a sheath was peeled off from a cable, the sheath was punched out by a No. 6 dumbbell to prepare a test specimen, and the test specimen was stretched at a stretching speed of 500mm/min to measure a tensile elongation. In the present example, the tensile elongation was 350% or more, the evaluation was "good", and if the tensile elongation was less than 350%, the evaluation was "poor".

(oil resistance)

The oil resistance of the jacket was measured by heating the jacket in oil at 120 ℃ for 18 hours using lubricating oil No.2 for test (IRM902 oil) specified in JIS K6258 to obtain the retention of tensile strength before and after heating. In the present example, the tensile strength retention of the jacket after the oil resistance test was 60% or more, the jacket was evaluated as "good" and if it was less than 60%, the jacket was evaluated as "poor".

(4) Evaluation results

The evaluation results of the examples and comparative examples are shown in table 1.

In examples 1 to 4, it was confirmed that no plasticizer bleeds out of the surface of the sheath. In addition, it was confirmed that the gel fraction was 70% or more and the degree of crosslinking of the sheath was high. Further, it was confirmed that the plasticizer was present in the sheath without bleeding out, and therefore, the tensile elongation was 350% or more and the flexibility was excellent. Further, it was confirmed that the jacket was excellent in oil resistance because of its high degree of crosslinking.

In examples 1 and 4, it was confirmed that the use of chlorinated paraffin as a non-mineral oil plasticizer increased the degree of crosslinking and oil resistance as compared with examples 2 and 3 in which phthalates were used. This is presumed to be because the chlorinated paraffin is included in the silane-crosslinked product at the time of silane crosslinking and contributes to the increase in the degree of crosslinking.

In comparative example 1, it was confirmed that since no plasticizer was added, the graft copolymerization of the silane compound was not inhibited by the plasticizer, and that a high degree of crosslinking and oil resistance were obtained. Further, it was confirmed that the plasticizer did not bleed out. However, it was confirmed that the tensile elongation was small and sufficient flexibility was not obtained in the sheath because no plasticizer was added.

In comparative example 2, it was confirmed that the plasticizer bleeds out on the surface of the sheath because paraffin process oil was used as the plasticizer. The reason for this is because the wax-based processing oil has a high aniline point and low compatibility with the rubber having polarity.

In comparative examples 3 and 4, it was confirmed that the graft copolymerization of the silane compound was inhibited by the plasticizer and the degree of crosslinking was lowered due to the use of the naphthene-based or aromatic-based plasticizer, and the oil resistance was also lowered. It was confirmed that naphthenic and aromatic compounds do not have low compatibility with polar components as paraffin compounds, and thus do not bleed out.

It was confirmed that the more the aromatic component contained in the mineral oil-based plasticizer is increased, the lower the crosslinking degree is, and the oil resistance is lowered as compared with comparative examples 2 to 4. This is presumably because when the silane compound is graft-copolymerized, the aromatic component contained in the plasticizer inhibits the reaction, and the graft ratio is lowered.

< preferred embodiment of the present invention >

Preferred embodiments of the present invention are described below.

[1] According to an aspect of the present invention, there is provided an electric wire cable,

which comprises a conductor and a coating layer for coating the outer periphery of the conductor,

the coating layer is formed by crosslinking a silane crosslinkable composition,

[2] In the electric wire and cable according to [1], the non-mineral oil plasticizer is at least 1 of chlorinated paraffin and phthalate plasticizer, for example.

[3] In the electric wire and cable according to [1] or [2], the amount of the non-mineral oil plasticizer is, for example, 1 to 30 parts by mass per 100 parts by mass of the chlorinated polyethylene.

[4] In any of the electric wires and cables according to [1] to [3], the silane compound has a methacryloyl group as an example.

[5] In the electric wire and cable of [4], the silane compound is exemplified by at least 1 of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane and 3-methacryloxypropylmethyldiethoxysilane.

[6] In any of the electric wires and cables of [1] to [5], the gel fraction of the coating layer after crosslinking is 70% or more as an example.

Description of the symbols

1 electric cable

2 insulated wire

10 conductor

11 insulating layer

12 coating layer (sheath)

Claims

1. A method for producing a crosslinked silane product, comprising the steps of:

a step of adding a non-mineral oil plasticizer, a silane compound and a peroxide to a chlorinated polyethylene composed of a base polymer to obtain a mixture;

heating and kneading the mixture to graft-copolymerize the silane compound and the chlorinated polyethylene in the presence of the peroxide to obtain a silane crosslinkable composition; and

a step of bringing the silane-crosslinkable composition into contact with water to obtain a silane-crosslinked product;

wherein the non-mineral oil plasticizer is at least 1 of chlorinated paraffin and phthalate plasticizer.

2. The method for producing a crosslinked silane product according to claim 1, wherein the amount of the non-mineral oil plasticizer is 1 to 30 parts by mass per 100 parts by mass of the chlorinated polyethylene.

3. The method for producing a silane crosslinked product according to claim 1 or 2, wherein the silane compound has a methacryloyl group.

4. The method for producing a crosslinked silane product according to claim 1, wherein the silane compound is at least 1 selected from the group consisting of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane and 3-methacryloxypropylmethyldiethoxysilane.

5. A method for manufacturing a cable comprises the following steps:

a step of adding a non-mineral oil plasticizer to a chlorinated polyethylene composed of a base polymer, and then adding a silane compound and a peroxide to obtain a mixture;

heating and kneading the mixture to graft-copolymerize the silane compound and the chlorinated polyethylene in the presence of the peroxide to obtain a silane crosslinkable composition;

a step of extruding the silane crosslinkable composition onto an insulating layer covering a conductor to form a sheath; and

and a step of bringing the sheath into contact with water to crosslink the silane.

6. The method for producing a cable according to claim 5, wherein the non-mineral oil plasticizer is at least 1 of chlorinated paraffin and a phthalate plasticizer.

7. The method for producing a cable according to claim 5 or 6, wherein the amount of the non-mineral oil plasticizer blended is 1 to 30 parts by mass with respect to 100 parts by mass of the chlorinated polyethylene.

8. The method for producing a cable according to any one of claims 5 to 7, wherein the silane compound has a methacryloyl group.

9. The method for producing a cable according to claim 8, wherein the silane compound is at least 1 of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane and 3-methacryloxypropylmethyldiethoxysilane.

10. A method for manufacturing an electric wire, comprising the steps of:

a step of extruding the silane crosslinkable composition onto a conductor to form an insulating layer; and

and a step of bringing the insulating layer into contact with water to crosslink the silane.

11. The method for manufacturing an electric wire according to claim 10, wherein the non-mineral oil plasticizer is at least 1 of chlorinated paraffin and a phthalate plasticizer.

12. The method for manufacturing an electric wire according to claim 10 or 11, wherein the amount of the non-mineral oil plasticizer blended is 1 to 30 parts by mass with respect to 100 parts by mass of the chlorinated polyethylene.

13. The method for manufacturing an electric wire according to any one of claims 10 to 12, wherein the silane compound has a methacryloyl group.

14. The method for manufacturing an electric wire according to claim 10, wherein the silane compound is at least 1 of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane.