JP2018110130A - Electric wire/cable, method for producing silane-crosslinked product, method for manufacturing electric wire, and method for manufacturing cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric wire/cable including a coating layer having a high degree of crosslinking and excellent flexibility.SOLUTION: The electric wire/cable is provided which includes a conductor and a coating layer covering the outer periphery of the conductor. The coating layer is formed by crosslinking a silane-crosslinkable composition. The silane-crosslinkable composition contains: a base polymer comprising a silane-grafted chlorinated polyethylene obtained by graft-copolymerizing a silane compound onto a chlorinated polyethylene; and a non-mineral oil plasticizer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing an electric cable and a silane crosslinked product, a method for manufacturing an electric wire, and a method for manufacturing a cable.

  Chlorinated polyethylene is a thermoplastic elastomer that excels in various properties such as heat resistance and wear resistance, and is a material for forming coating layers (eg, insulation layers and sheaths) covering the outer periphery of conductors in electric cables such as electric wires and cables. It is used as.

  Generally, when a 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 (see, for example, Patent Document 1). Specifically, when silane crosslinking is performed on chlorinated polyethylene to form a coating layer, first, a silane compound is blended with chlorinated polyethylene and kneaded. Subsequently, a silane compound is graft-copolymerized to chlorinated polyethylene 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 body is brought into contact with moisture to advance a crosslinking reaction, thereby forming a silane-crosslinked coating layer.

Japanese Patent Publication No. 50-35540

  By the way, 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 that imparts flexibility to the coating layer, a stabilizer that imparts resistance to the external environment, and carbon black that imparts abrasion resistance are blended. These additives are generally blended at the same time when a silane compound is blended with chlorinated polyethylene from the viewpoint of simplifying the production process. These are kneaded and then heated to graft copolymerize the silane compound with chlorinated polyethylene in the presence of the additive.

However, when the silane compound is graft copolymerized with chlorinated polyethylene in the presence of a plasticizer among the additives, 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 grafting rate) is low, and eventually a sufficient degree of crosslinking cannot be obtained when silane crosslinking is performed. There is.
On the other hand, it is conceivable to add a plasticizer having an adverse effect on graft copolymerization after graft copolymerization. However, since graft copolymerization is carried out at a relatively high temperature, it is possible to plasticize a silane crosslinkable composition heated to a high temperature. When the agent is blended, the plasticizer may volatilize. Moreover, since it takes time to disperse the plasticizer in the silane crosslinkable composition, premature crosslinking occurs, making it difficult to extrude the silane crosslinkable composition and form a coating layer.
In the case where a plasticizer is not blended, the formed coating layer has a sufficient degree of crosslinking, but has a low elongation and cannot satisfy the flexibility required for the coating layer.

  The present invention has been made in view of the above problems, and has a high degree of cross-linking and an electric wire cable including a coating layer having excellent flexibility, a method for producing a silane cross-linked product, a method for producing an electric wire, and a method for producing a cable. The purpose is to provide.

According to one aspect of the invention,
Comprising a conductor and a coating layer covering the outer periphery of the conductor;
The coating layer is formed by crosslinking a silane crosslinkable composition,
The silane crosslinkable composition provides an electric cable containing a base polymer made of silane-grafted chlorinated polyethylene obtained by graft copolymerizing a silane compound with chlorinated polyethylene and a non-mineral oil plasticizer.
According to another aspect of the invention,
Adding a non-mineral oil plasticizer to chlorinated polyethylene comprising a base polymer and then adding a silane compound and a peroxide to obtain a mixture;
A step of graft-copolymerizing the silane compound to the chlorinated polyethylene in the presence of the peroxide by heating and kneading the mixture to obtain a silane crosslinkable composition;
There is provided a method for producing a crosslinked silane product comprising a step of bringing the silane crosslinkable composition into contact with water to obtain a silane crosslinked product.
According to another aspect of the invention,
Adding a non-mineral oil plasticizer to chlorinated polyethylene comprising a base polymer and then adding a silane compound and a peroxide to obtain a mixture;
A step of graft-copolymerizing the silane compound to the chlorinated polyethylene in the presence of the peroxide by heating and kneading the mixture to obtain a silane crosslinkable composition;
Forming a sheath by extruding the silane crosslinkable composition on an insulating layer coated with a conductor; and
There is provided a method for producing a cable comprising the step of bringing the sheath into contact with water and crosslinking the silane.
According to another aspect of the invention,
Adding a non-mineral oil plasticizer to chlorinated polyethylene comprising a base polymer and then adding a silane compound and a peroxide to obtain a mixture;
A step of graft-copolymerizing the silane compound to the chlorinated polyethylene in the presence of the peroxide by heating and kneading the mixture to obtain a silane crosslinkable composition;
Extruding the silane crosslinkable composition on the conductor to form an insulating layer;
There is provided a method for producing an electric wire comprising a step of bringing the insulating layer into contact with water to cause silane crosslinking.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of an electric wire cable, a silane crosslinked material, an electric wire, and a cable provided with the coating layer which is high in a bridge degree and is excellent in flexibility is obtained.

It is sectional drawing which shows schematic structure of the cable which concerns on one Embodiment of this invention. It is the schematic which shows the grafting process using the single screw extruder in an Example. It is the schematic which shows preparation of the cable in an Example.

  As described above, when a plasticizer is blended as an additive, graft copolymerization of the silane compound is inhibited, so that a sufficient degree of crosslinking may not be obtained when silane crosslinking is performed. The plasticizer is an additive generally used for enhancing the flexibility of the coating layer. For example, mineral oil refined from crude oil is used. Mineral oils include paraffinic oils, naphthenic oils, and aromatic oils depending on the content ratios of paraffin, naphthene, and aromatic components. However, according to the study by the present inventors, it has been found that these mineral oils greatly inhibit graft copolymerization of silane compounds among plasticizers, so that a sufficient degree of crosslinking cannot be obtained when silane crosslinking is performed.

  From this, the present inventors examined using a non-mineral oil system, not a mineral oil system, as a plasticizer. For example, non-mineral oil systems such as chlorinated paraffin and phthalate plasticizers. According to the plasticizer, the grafting rate to chlorinated polyethylene can be increased without inhibiting graft copolymerization of the silane compound. Thereby, a high degree of crosslinking can be obtained when silane crosslinking is performed. Moreover, since the non-mineral oil plasticizer is also excellent in compatibility with the silane-grafted chlorinated polyethylene, it is difficult to elute from the coating layer, and bleed can be suppressed. Therefore, according to the non-mineral oil plasticizer, a coating layer having a high degree of crosslinking and excellent flexibility can be formed.

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

<One Embodiment of the Present Invention>
Hereinafter, an embodiment of the present invention will be described.

(1) Silane crosslinkable composition First, the silane crosslinkable composition which forms the coating layer of an electric wire cable is demonstrated.

  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 to the chlorinated polyethylene in the presence of the peroxide. Silane-grafted chlorinated polyethylene has a silane group derived from the graft-copolymerized silane compound in the molecular structure, and when it comes into contact with water, the silane group in the molecular structure is hydrolyzed to form a silanol group. The silanol groups are dehydrated and condensed to form a crosslinked structure, whereby silane crosslinking is performed.

  Chlorinated polyethylene has a structure in which a part of hydrogen in a hydrocarbon skeleton such as polyethylene is substituted with a chlorine atom having a high electronegativity, and is a highly polar component. The chlorinated polyethylene can be obtained, for example, by blowing chlorine gas into an aqueous suspension obtained by suspending and dispersing linear polyethylene (such as low density polyethylene or high density polyethylene) in water. The degree of chlorination of the chlorinated polyethylene is preferably 25% or more and 45% or less from the viewpoint of obtaining a good balance of various properties such as heat resistance, oil resistance and flame retardancy of the coating layer, and further when forming the coating layer. From the viewpoint of improving workability, it is more preferably 30% or more and 40% or less.

  The silane compound has an unsaturated bond group and a hydrolyzable silane group. A silane compound introduce | transduces a silane group into chlorinated polyethylene by being graft-copolymerized to chlorinated polyethylene by an unsaturated bond group.

  The unsaturated bond 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 methacryl group, and an acrylic group. Among these, a methacryl group is preferable as the unsaturated bond group. A methacrylic silane compound having a methacrylic group is more compatible with a chlorinated polyethylene than a vinylsilane compound having a vinyl group, and can be easily dispersed in the chlorinated polyethylene. A cross-linked structure can be formed. Furthermore, it is lower in flammability than vinyl silane compounds and is excellent in handleability.

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

  Specific examples of the silane compound include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. Can be used.

  The amount of silane compound graft copolymerized with chlorinated polyethylene, that is, the amount of silane compound blended with chlorinated polyethylene is the degree of crosslinking of the final molded product (coating layer) or the reaction conditions for crosslinking. It may be changed appropriately according to (for example, temperature, time, etc.). Specifically, the compounding amount of the silane compound is preferably 0.1 parts by mass or more and 10 parts by mass or less, and 1.0 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of chlorinated polyethylene. More preferably. By setting such a blending amount, an appropriate degree of crosslinking can be obtained when silane crosslinking is performed.

  The peroxide is for graft copolymerizing a silane compound with chlorinated polyethylene. Specifically, the peroxide generates oxy radicals by thermal decomposition. Oxy radicals generate chlorinated polyethylene radicals by extracting hydrogen from chlorinated polyethylene. And the radical of chlorinated polyethylene reacts with the unsaturated bond group (for example, vinyl group, methacryl group, etc.) which a silane compound has, and a silane compound will be graft-copolymerized to chlorinated polyethylene. Thus, the peroxide generates oxy radicals and causes graft copolymerization of the silane compound onto chlorinated polyethylene.

  As the peroxide, for example, an organic peroxide can be used. Organic peroxide has a high hydrogen abstraction ability for extracting hydrogen from chlorinated polyethylene, and can be thermally decomposed at a temperature at which chlorinated polyethylene is hardly deteriorated (it is difficult to dehydrochlorinate) to generate oxy radicals. Since the deterioration start temperature of chlorinated polyethylene is about 200 ° C., it is preferable to use an organic peroxide having a one-minute half-life temperature of 120 ° C. or more and 200 ° C. or less as the peroxide. From the viewpoint of shortening the time required for the grafting reaction, it is better to use an organic peroxide having a one-minute half-life temperature of 150 ° C. or higher and 200 ° C. or lower. The 1-minute half-life temperature is a temperature at which the half-life of the peroxide is 1 minute.

  Specifically, as the peroxide, dicumyl peroxide, 1,1-di (t-butylperoxy) cyclohexane, t-butylperoxyisopropyl carbonate, t-amylperoxyisopropyl carbonate, 2,5 dimethyl 2,5 di (t-butylperoxy) hexane, di-t-butyl peroxide, di-t-amyl peroxide, 1,1-di (t-amylperoxy) cyclohexane, t-butylperoxy 2- Ethyl hexyl carbonate or the like can be used. These may be used alone or in combination of two or more. Among these, dicumyl peroxide having a 1 minute half-life temperature of about 175 ° C. may be used.

  The compounding amount of the peroxide may be appropriately changed according to the compounding amount of the silane compound, and is preferably 0.03 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the chlorinated polyethylene. By setting such a blending amount, an appropriate degree of crosslinking can be obtained when silane crosslinking is performed.

  The silane crosslinkable composition is blended with a plasticizer in order to increase the flexibility of the coating layer. In this embodiment, as described above, the viewpoint of reacting the silane compound so as to increase the grafting rate. Therefore, a non-mineral oil plasticizer is used. Since this plasticizer does not significantly inhibit the graft copolymerization of the silane compound to chlorinated polyethylene, the grafting rate of the silane compound can be increased. And since it is excellent in compatibility with a silane graft chlorinated polyethylene, it is hard to bleed from a silane crosslinkable composition.

The non-mineral oil plasticizer is not particularly limited as long as it has an atom with a large electronegativity or a functional group with a large polarity, but at least one of a chlorinated paraffin and a phthalate ester plasticizer may be used. preferable.
Chlorinated paraffin has the same chemical structure as chlorinated polyethylene and is incorporated into the crosslinked product when silane-grafted chlorinated polyethylene is crosslinked with silane, thereby improving the degree of crosslinking and making the crosslinked product oil resistant. Etc. can be improved.
Since the phthalate ester plasticizer has an ester group and is more polar than the mineral oil plasticizer, the oil resistance of the crosslinked product can be improved.
From the viewpoint of further improving the degree of crosslinking of the coating layer, chlorinated polyolefin incorporated in the crosslinked body is more preferable.

  The blending amount of the non-mineral oil plasticizer is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the chlorinated polyethylene. If it is such a compounding quantity, the bleeding from a coating layer can be suppressed, maintaining the flexibility of a coating layer highly.

  In addition, other additives other than a plasticizer may be mix | blended with the silane crosslinkable composition. As another additive, for example, a silanol condensation catalyst that promotes silane crosslinking can be used. As the silanol condensation catalyst, for example, a group II element such as magnesium and calcium, a group VIII element such as cobalt and iron, a metal element such as tin, zinc and titanium, and a metal compound containing these elements can be used. In addition, metal salts of octylic acid and adipic acid, amine compounds, acids, and the like can be used. Specifically, dioctyltin dineodecanoate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctaate, stannous acetate, stannous carbrate, lead naphthenate, zinc caprylate, cobalt naphthenate, etc. Metal salts, 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 anti-aging agents), fillers such as carbon black, flame retardants, lubricants, copper damage discoloration inhibitors, crosslinking aids, stabilizers, and the like may be used.

(2) Manufacturing method of silane crosslinkable composition Next, the manufacturing method of the silane crosslinkable composition mentioned above is demonstrated.

  First, a non-mineral oil plasticizer is added to chlorinated polyethylene and kneaded. Since the non-mineral oil plasticizer is compatible with the chlorinated polyethylene, the plasticizer can be dispersed in 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 chlorinated polyethylene. In addition, when adding a plasticizer, you may add other additives, such as antioxidant and carbon black, for example.

  Subsequently, a silane compound and a peroxide are added to a mixture in which a plasticizer is dispersed in chlorinated polyethylene and kneaded. 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 agglomeration. The silane compound ranges from 0.1 parts by weight to 10 parts by weight with respect to 100 parts by weight of chlorinated polyethylene, and the peroxide ranges from 0.03 parts by weight to 3.0 parts by weight with respect to 100 parts by weight of chlorinated polyethylene. It is preferable to mix with.

  Subsequently, the mixture to which the silane compound and the peroxide are added is heated and kneaded, whereby the silane compound is graft copolymerized with the chlorinated polyethylene in the presence of the peroxide. Thereby, a silane-grafted chlorinated polyethylene is formed, and a silane crosslinkable composition containing this and a non-mineral oil plasticizer is obtained. In this embodiment, since the silane compound is uniformly dispersed without agglomerating in the chlorinated polyethylene and then graft copolymerized, the silane-grafted chlorinated polyethylene has a high silane compound grafting rate, and Silane groups are uniformly introduced. Moreover, since the non-mineral oil plasticizer has compatibility with the silane-grafted chlorinated polyethylene, bleeding is suppressed.

  In addition, when the mixture is kneaded, it may be kneaded using a kneading reaction apparatus such as a roll machine, an extruder, a kneader, a mixer, or an autoclave. Further, kneading conditions and graft reaction conditions (temperature, time, etc.) are not particularly limited.

(3) Silane cross-linked product The silane cross-linked product is obtained by bringing the silane cross-linkable composition mentioned above into contact with water and silane-grafted chlorinated polyethylene by silane cross-linking. In the present embodiment, since the silane-grafted chlorinated polyethylene has a high grafting rate and silane groups are uniformly introduced into the chemical structure, the silane crosslinked product obtained therefrom has a high degree of crosslinking and a crosslinked structure. It will be formed homogeneously.

The cross-linked silane has a high degree of cross-linking, and the gel fraction, which is an index of the degree of cross-linking, is preferably 70% or more. When the gel fraction is less than 70%, the degree of cross-linking of the silane cross-linked product is low, so that, for example, when it is formed as a coating layer for electric cables, sufficient mechanical properties cannot be obtained. The upper limit of the gel fraction is not particularly limited, and the higher the gel fraction, the more cross-linked structures are formed in the silane cross-linked product, and the mechanical properties become higher.
In addition, a gel fraction is calculated | required as follows. First, a sample formed of a silane cross-linked product is immersed in xylene, and xylene is heated and boiled. Thereafter, a sample that remains without being dissolved in xylene (sample after extraction with hot xylene) is taken out and dried, and the mass of the sample after extraction with hot xylene is measured. And the gel fraction of a silane crosslinked product is calculated | required by calculating the ratio of the mass of the sample after extracting with hot xylene with respect to the mass of the sample before extracting with hot xylene. When the mass of the sample before extraction with hot xylene is a, and the mass of the sample after extraction with hot xylene is b, the gel fraction R is expressed by the following formula.

R (%) = (b / a) × 100
Moreover, the silane cross-linked product contains a non-mineral oil plasticizer. Therefore, the silane cross-linked product is easily stretched and has excellent flexibility. In addition, since the plasticizer is highly compatible, bleeding of the plasticizer is suppressed.

(4) Electric wire cable Next, the electric wire cable which concerns on one Embodiment of this invention is demonstrated, referring drawings. In this embodiment, the case of a cable having a sheath as a covering 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 this embodiment includes a conductor 10. As the conductor 10, a copper wire made of low-oxygen copper, oxygen-free copper, or the like, a copper alloy wire, a metal wire made of aluminum, silver, or the like, or a stranded wire formed by twisting metal wires can be used. The outer diameter of the conductor 10 can be appropriately changed according to the use of the cable 1.

  An insulating layer 11 is provided so as 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 can be appropriately changed according to the use of the cable 1.

  An outer cover layer 12 (sheath 12) is provided so as to cover the outer periphery of the insulating layer 11. The sheath 12 is formed of a silane crosslinked product obtained by crosslinking a silane crosslinkable composition. The sheath 12 has a high degree of crosslinking and is configured so that the gel fraction is 70% or more.

The cable 1 is manufactured as follows, for example.
First, for example, a copper wire is prepared as the conductor 10. Subsequently, a resin composition containing ethylene propylene rubber is extruded by an extruder so as to cover the outer periphery of the conductor 10 to form the insulating layer 11 having a predetermined thickness. Subsequently, the sheath 12 is formed by extruding the silane crosslinkable composition described above at a predetermined thickness so as to cover the outer periphery of the insulating layer 11. Thereafter, the sheath 12 is exposed to an environment of, for example, a temperature of 80 ° C. and a relative humidity of 90% to react with moisture, whereby the silane crosslinkable composition forming the sheath 12 is crosslinked with silane.

<Other Embodiments of the Present Invention>
As mentioned above, although one Embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the summary, it can change suitably.

  In the above-described embodiment, the cable 1 is described as an example of the electric cable, but the present invention is not limited to this, and may be configured as an insulated electric wire including an insulating layer as a covering layer. In this case, as in the case of forming the sheath 12 in the above-described embodiment, an insulating layer may be formed by extruding the silane crosslinkable composition on the outer periphery of the conductor, and the insulating layer may be brought into contact with water for silane crosslinking.

  In the above-described embodiment, the case where the cable 1 includes one electric wire provided with an insulating layer on the outer periphery of the conductor has been described. However, the cable 1 is a stranded wire obtained by twisting two or more electric wires. You may prepare.

  Next, examples of the present invention will be described.

  The materials used in Examples and Comparative Examples are as follows.

Chlorinated polyethylene (Mooney viscosity at 121 ° C. (ML1 + 4): 55, heat of fusion: less than 1.0 J / g): “CM352L” manufactured by Hangzhou Science & Technology Co., Ltd.
-Hydrotalcite: “Mugcellar 1” manufactured by Kyowa Chemical Industry Co., Ltd.
Epoxidized soybean oil: “New Sizer 510R” manufactured by Nippon Oil & Fats Co., Ltd.
・ Peroxide (Dicumyl peroxide): “DCP” manufactured by NOF Corporation
Silane compound (3-methacryloxypropyltrimethoxysilane): “KBM-503” manufactured by Shin-Etsu Chemical Co., Ltd.
Silane compound (3-methacryloxypropyltriethoxysilane): “KBE-503” manufactured by Shin-Etsu Chemical Co., Ltd.
・ Plasticizer (chlorinated paraffin): “Empara 40” manufactured by Ajinomoto Fine Techno Co., Ltd.
・ Plasticizer (di-2-ethylhexyl phthalate): Shin Nippon Rika Co., Ltd. “Sanso Sizer Ar DOP”
・ Plasticizer (Diisononyl phthalate): Shin Nippon Rika Co., Ltd.
Plasticizer (paraffinic process oil, carbon atom ratio in the component; paraffin / naphthene / aromatic = 68/28/4): Nippon Sun Oil Co., Ltd. “Thamper 115”
Plasticizer (naphthene-based process oil, carbon atom ratio in the component; paraffin / naphthene / aromatic = 49 / 35.5 / 15.5): “NP-24” manufactured by Idemitsu Kosan Co., Ltd.
Plasticizer (aromatic process oil, carbon atom ratio in components; paraffin / naphthene / aromatic = 20/32/48): Fuji Kosan Co., Ltd. “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 Co., Ltd.
Lubricant (polyethylene wax (PE wax, molecular weight: 2800)): “High Wax NL-200” manufactured by Mitsui Chemicals, Inc.
・ Lubricant (ethylenebisoleic acid amide): “Sripac-O” manufactured by Nippon Kasei Co., Ltd.
Phenol antioxidant (4,4′-thiobis (3-methyl-6-tert-butylphenol)): “NOCRACK 300R” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Amine-based antioxidant (2,2,4-trimethyl-1,2-dihydroquinoline polymer): “NOCRACK 224” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Silanol condensation catalyst (dioctyltin dineodecanoate): “Neostan U-830” manufactured by Nitto Kasei Co., Ltd.

(1) Preparation of silane crosslinkable composition <Example 1>
First, an additive such as a plasticizer was added to the base polymer.
Specifically, first, as shown in Table 1 below, in a pressure type kneader, 100 parts by mass of chlorinated polyethylene, 6 parts by mass of hydrotalcite as a stabilizer, and epoxidized soybean oil as a stabilizer 6 parts by weight, 3 parts by weight of PE wax as a lubricant, 1 part by weight of ethylenebisoleic acid amide as a lubricant, 40 parts by weight of carbon, and non-mineral oil-based chlorinated paraffin as a plasticizer 10 parts by mass were added and kneaded for 5 minutes at a blade rotation number of 20 rpm. At this time, the kneader tank was not particularly heated, and the temperature of the kneaded product was raised to about 100 ° C. due to heat generation of the rubber component.

Subsequently, a silane compound and a peroxide were added to the kneaded product.
A silane mixture in which 0.5 parts by mass of dicumyl peroxide as a peroxide was dissolved in 3.35 parts by mass of 3-methacryloxypropyltrimethoxysilane, which is a silane compound, was put into the above-mentioned pressure type kneader, The mixture was further kneaded for 5 minutes at a blade rotation number of 20 rpm. The temperature of the kneaded product after kneading was about 110 ° C.

Subsequently, the kneaded product was subjected to silane grafting treatment using a single screw extruder 100 shown in FIG.
Specifically, the kneaded material was continuously supplied into the cylinder 103a from the hopper 101 of the single screw extruder 100, and sent out from the cylinder 103a to the cylinder 103b by the rotation of the screw 102. At this time, the kneaded material was heated and softened and kneaded by the cylinders 103a and 103b to graft copolymerize the chlorinated polyethylene with the silane compound. Thereby, the silane graft | grafting chlorinated polyethylene was formed and the silane crosslinkable composition containing it was obtained. Then, the silane crosslinkable composition was sent to the head part 104 of the extruder 100, and the strand 20 (length 150 cm) of the silane crosslinkable composition was extruded from the die 105. Then, the strand 20 was introduced into the water tank 106, cooled with water, and drained with an air wiper 107. Then, the strand 20 was pelletized with the pelletizer 108, and the pellet 21 which consists of a silane crosslinkable composition was formed. And in order to prevent the mutual adhesion of the pellet 21, the talc 1 mass part was applied to the pellet 21, and the compound of Example 1 was obtained.
In the silane grafting process, a 40 mm single screw single screw extruder 100 was used. The ratio L / D between the screw diameter D and the screw length L was 25. Further, the temperature of the cylinder 103a was 80 ° C., the temperature of the cylinder 103b was 200 ° C., and the temperature of the head portion 104 was 200 ° C. Further, as the screw 102, a full flight shape with a compression ratio of 2.0 was used. The rotation speed of the screw 102 was 20 rpm. Further, a die having a hole diameter of 5 mm and three holes was used as the die 105.

Subsequently, a masterbatch containing an antioxidant and a silanol condensation catalyst was prepared separately from the above compound.
Specifically, in a pressure kneader, 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, phenolic antioxidant 0.08 parts by mass of the agent, 1.5 parts by mass of the amine-based antioxidant, and 2 parts by mass of the silanol condensation catalyst were added and kneaded for 10 minutes at a blade rotation number of 20 rpm. And this kneaded material was continuously supplied to the single screw extruder 100 shown in FIG. 2, kneaded under the same conditions as described above, extruded into a strand shape, and pelletized to obtain master batch pellets. In the pressure type kneader, the temperature of the kneaded product was raised to 100 ° C. due to heat generation of the rubber component.

  Finally, the silane crosslinkable composition of Example 1 was prepared by adding the pellet master batch to the pellet compound and dry blending. At this time, the master batch was added to the compound at a ratio such that the master batch was 2.5 parts by mass with respect to 100 parts by mass of the chlorinated polyethylene in the compound.

<Examples 2 and 3>
In Examples 2 and 3, as shown in Table 1, except that the type of plasticizer contained in the silane crosslinkable composition was changed from chlorinated paraffin to di-2-ethylhexyl phthalate or diisononyl phthalate. A silane crosslinkable composition was prepared in the same manner as in Example 1 to prepare a cable.

<Example 4>
In Example 4, the type of the silane compound was changed from 3-methacryloxypropyltrimethoxysilane to 3-methacryloxypropyltriethoxysilane, and the blending amount was changed from 3.35 parts by mass to 3.92 parts by mass. A silane crosslinkable composition was prepared in the same manner as in Example 1 to produce a cable.

<Comparative Example 1>
In Comparative Example 1, a silane crosslinkable composition was prepared and a cable was prepared in the same manner as in Example 1 except that no plasticizer was added.

<Comparative Examples 2-4>
In Comparative Examples 2 to 4, a silane crosslinkable composition was prepared in the same manner as in Example 1 except that the type of plasticizer was changed from a non-mineral oil type to a mineral oil type to produce a cable. As the mineral oil plasticizer, paraffinic process oil was used in Comparative Example 2, naphthenic process oil was used in Comparative Example 3, and aromatic process oil was used in Comparative Example 4.

(2) Production of Cable Next, the cables 1 of Examples 1 to 4 and Comparative Examples 1 to 4 were produced by extruding the prepared silane crosslinkable composition with a single screw extruder 100 shown in FIG. Specifically, a copper conductor having a cross-sectional area of 8 mm 2 is inserted as the conductor 10 into the die 105 of the single screw extruder 100, and ethylene propylene rubber (EP rubber) is extruded to the outer periphery thereof to insulate 1.0 mm in thickness. The cable 1 was produced by forming the layer 11 and extruding the above-mentioned silane crosslinkable composition on the outer periphery of the insulating layer 11 to form a sheath 12 having a thickness of 1.7 mm. Thereafter, the cable 1 was stored in a constant temperature and humidity chamber at a temperature of 60 ° C. and a relative humidity of 95% for 24 hours, and subjected to silane crosslinking treatment.
In manufacturing the cable 1, a 20 mm single-screw single-screw extruder 100 was used. The ratio L / D between the screw diameter D and the screw length L was 15. The temperature of the cylinder 103a was 120 ° C., the temperature of the cylinder 103b was 150 ° C., the temperature of the crosshead portion 110 was 150 ° C., the temperature of the neck 109 was 150 ° C., and the temperature of the die 105 was 130 ° C. Moreover, the rotation speed of the screw 102 was 15 rpm, and the screw 102 having a full flight shape and a compression ratio of 2.0 was used.

(3) Evaluation method The produced cable was evaluated by the following method.

(With or without bleeding)
The presence / absence of bleed was determined by visually observing the surface appearance of the cable. If there was no bleed-out of the plasticizer, the test was “O”, and if bleed-out was confirmed, the test was “X”.

(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, 0.5 g of a sample was taken from the sheath after silane crosslinking, and this sample was put in a 40 mesh brass wire mesh. Subsequently, the sample was extracted with xylene in a 110 ° C. oil bath. After the extraction treatment, the remaining sample was taken out from xylene and vacuum-dried at 80 ° C. for 4 hours. Then, the mass of the remaining sample after drying was weighed, and the gel fraction R of the sample was calculated from the following equation using the mass a of the sample before xylene extraction and the mass b of the remaining sample after xylene extraction.
R (%) = b / a × 100
In this example, the case where the gel fraction after cross-linking is 70% or more was regarded as acceptable “◯”, and the case where the gel fraction was less than 70% was regarded as unacceptable “x”.

(Tensile elongation)
In order to evaluate the flexibility of the sheath, the tensile elongation of the sheath was measured.
First, the sheath was peeled off from the cable, and the sheath was punched with a No. 6 dumbbell to prepare a test sample. The test sample was pulled at a tensile speed of 500 mm / min, and the tensile elongation was measured. In this example, if the tensile elongation was 350% or more, it was judged as acceptable “◯”, and if it was less than 350%, it was judged as unacceptable “x”.

(Oil resistance)
The oil resistance of the sheath is the test lubricating oil No. specified in JIS K6258. 2 (IRM902 oil) was used to heat the sheath in oil at 120 ° C. for 18 hours, and the residual ratio of tensile strength before and after heating was determined. In this example, if the residual tensile strength of the sheath after the oil resistance test was 60% or more, it was judged as “good”, and if it was less than that, it was judged as “bad”.

(4) Evaluation results Table 1 shows the evaluation results for each of the examples and comparative examples.

In Examples 1 to 4, it was confirmed that the plasticizer was not bleeding on the surface of the sheath. Further, it was confirmed that the gel fraction was 70% or more and the degree of cross-linking of the sheath was high. Further, since the plasticizer was present in the sheath without bleeding, the tensile elongation was 350% or more, and it was confirmed that the plasticizer was excellent in flexibility. Moreover, since the sheath has a high degree of crosslinking, it was confirmed that the sheath was excellent in oil resistance.
In Examples 1 and 4, since chlorinated paraffin was used as the non-mineral oil plasticizer, it was confirmed that the degree of crosslinking and oil resistance were higher than those in Examples 2 and 3 using phthalates. This is presumably because chlorinated paraffin was incorporated into the silane cross-linked product during silane cross-linking and contributed to the improvement of the degree of cross-linking.

  In Comparative Example 1, since no plasticizer was added, it was confirmed that the graft copolymerization of the silane compound was not inhibited by the plasticizer, and a high degree of crosslinking and oil resistance were obtained. It was also confirmed that no plasticizer bleeding occurred. However, since the plasticizer was not added, it was confirmed that the sheath had a small tensile elongation and sufficient flexibility could not be obtained.

  In Comparative Example 2, since paraffinic process oil was used as a plasticizer, it was confirmed that the plasticizer bleeds on the surface of the sheath. This is because paraffinic process oil has a high aniline point and low compatibility with polar rubber.

  In Comparative Examples 3 and 4, since a naphthenic or aromatic system was used as a plasticizer, the graft copolymerization of the silane compound was hindered by the plasticizer, and the degree of cross-linking was lowered, and oil resistance was also lowered accordingly. Was confirmed. In addition, it was confirmed that naphthenes and aromatics do not bleed because their compatibility with polar components is not as low as that of paraffins.

  When Comparative Examples 2 to 4 were compared, it was confirmed that as the aromatic component contained in the mineral oil-based plasticizer increased, the degree of cross-linking became lower and the oil resistance was lowered accordingly. This is presumed that when the silane compound is graft-copolymerized, the aromatic component contained in the plasticizer inhibits the reaction and the grafting rate is lowered.

<Preferred embodiment of the present invention>
Hereinafter, preferred embodiments of the present invention will be additionally described.

[Appendix 1]
According to one aspect of the invention,
Comprising a conductor and a coating layer covering the outer periphery of the conductor;
The coating layer is formed by crosslinking a silane crosslinkable composition,
The silane crosslinkable composition provides an electric cable containing a base polymer made of silane-grafted chlorinated polyethylene obtained by graft copolymerizing a silane compound with chlorinated polyethylene and a non-mineral oil plasticizer.

[Appendix 2]
In the cable of appendix 1, preferably,
The non-mineral oil plasticizer is at least one of a chlorinated paraffin and a phthalate ester plasticizer.

[Appendix 3]
In the wire cable of appendix 1 or 2,
The blending amount of the non-mineral oil plasticizer is 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the chlorinated polyethylene.

[Appendix 4]
In the electric wire cable of any one of appendices 1 to 3, preferably,
The silane compound has a methacryl group.

[Appendix 5]
In the wire cable of appendix 4, preferably,
The silane compound is at least one of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane.

1 Cable 2 Insulated Wire 10 Conductor 11 Insulating Layer 12 Covering Layer (Sheath)

Claims (20)

Comprising a conductor and a coating layer covering the outer periphery of the conductor;
The coating layer is formed by crosslinking a silane crosslinkable composition,
The said silane crosslinkable composition is an electric cable containing the base polymer which consists of a silane graft | grafting chlorinated polyethylene which graft-copolymerized the silane compound to the chlorinated polyethylene, and a non-mineral oil type plasticizer.   The electric wire cable according to claim 1, wherein the non-mineral oil plasticizer is at least one of a chlorinated paraffin and a phthalate ester plasticizer.   The electric wire cable according to claim 1 or 2, wherein a blending amount of the non-mineral oil plasticizer is 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the chlorinated polyethylene.   The electric wire cable according to any one of claims 1 to 3, wherein the silane compound has a methacryl group.   The silane compound is at least one of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. The electric cable described in 1. Adding a non-mineral oil plasticizer, a silane compound and a peroxide to chlorinated polyethylene comprising a base polymer to obtain a mixture;
A step of graft-copolymerizing the silane compound to the chlorinated polyethylene in the presence of the peroxide by heating and kneading the mixture to obtain a silane crosslinkable composition;
A method for producing a crosslinked silane product comprising a step of bringing the silane crosslinkable composition into contact with water to obtain a silane crosslinked product.   The method for producing a crosslinked silane product according to claim 6, wherein the non-mineral oil plasticizer is at least one of a chlorinated paraffin and a phthalate ester plasticizer.   The manufacturing method of the silane crosslinked product of Claim 6 or 7 whose compounding quantity of the said non-mineral oil type plasticizer is 1 to 30 mass parts with respect to 100 mass parts of the said chlorinated polyethylene.   The method for producing a crosslinked silane product according to any one of claims 6 to 8, wherein the silane compound has a methacryl group.   The silane compound is at least one of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. The manufacturing method of the silane crosslinked material of description. Adding a non-mineral oil plasticizer to chlorinated polyethylene comprising a base polymer and then adding a silane compound and a peroxide to obtain a mixture;
A step of graft-copolymerizing the silane compound to the chlorinated polyethylene in the presence of the peroxide by heating and kneading the mixture to obtain a silane crosslinkable composition;
Forming a sheath by extruding the silane crosslinkable composition on an insulating layer coated with a conductor; and
A method for producing a cable, comprising a step of bringing the sheath into contact with water and crosslinking the silane.   The cable manufacturing method according to claim 11, wherein the non-mineral oil plasticizer is at least one of a chlorinated paraffin and a phthalate ester plasticizer.   The manufacturing method of the cable of Claim 11 or 12 whose compounding quantity of the said non-mineral oil type plasticizer is 1 to 30 mass parts with respect to 100 mass parts of the said chlorinated polyethylene.   The cable manufacturing method according to claim 11, wherein the silane compound has a methacryl group.   The silane compound is at least one of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. The manufacturing method of the cable as described in 2. Adding a non-mineral oil plasticizer to chlorinated polyethylene comprising a base polymer and then adding a silane compound and a peroxide to obtain a mixture;
A step of graft-copolymerizing the silane compound to the chlorinated polyethylene in the presence of the peroxide by heating and kneading the mixture to obtain a silane crosslinkable composition;
Extruding the silane crosslinkable composition on the conductor to form an insulating layer;
The manufacturing method of the electric wire which consists of the process of making the said insulating layer contact with water and carrying out a silane bridge | crosslinking.   The method of manufacturing an electric wire according to claim 16, wherein the non-mineral oil plasticizer is at least one of a chlorinated paraffin and a phthalate ester plasticizer.   The manufacturing method of the electric wire of Claim 16 or 17 whose compounding quantity of the said non-mineral oil type plasticizer is 1 to 30 mass parts with respect to 100 mass parts of the said chlorinated polyethylene.   The manufacturing method of the electric wire in any one of Claims 16-18 in which the said silane compound has a methacryl group.   The silane compound is at least one of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. The manufacturing method of the electric wire of description.

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