WO2016021611A1

WO2016021611A1 - Silane-grafted composition and method for producing same, as well as wire and cable using said composition

Info

Publication number: WO2016021611A1
Application number: PCT/JP2015/072121
Authority: WO
Inventors: 新吾芦原; 貴青山; 浩貴矢崎
Original assignee: 日立金属株式会社
Priority date: 2014-08-08
Filing date: 2015-08-04
Publication date: 2016-02-11
Also published as: JP2016037563A; CN106661306A

Abstract

To minimize deformation due to heating of silane-grafted chlorinated polyethylene. A silane-grafted composition in one embodiment of the present invention contains silane-grafted chlorinated polyethylene obtained by graft-polymerizing a silane compound to chlorinated polyethylene, and silane-grafted polyethylene obtained by graft-polymerizing a silane compound to polyethylene.

Description

Silane graft composition and method for producing the same, and electric wire and cable using the composition

The present invention relates to a silane graft composition and a method for producing the same, and an electric wire and a cable using the composition.

Chlorinated polyethylene is widely used as a material for forming a coating layer such as an electric wire insulation layer or a cable jacket layer (sheath). Generally, a chlorinated polyethylene is subjected to a crosslinking treatment when formed in a coating layer. As the crosslinking treatment, for example, silane crosslinking using a silane compound (so-called silane coupling agent) is widely used (see, for example, Patent Document 1). Silane crosslinking is carried out by graft polymerizing a silane compound to chlorinated polyethylene and bringing the resulting silane-grafted chlorinated polyethylene into contact with moisture.

For example, when manufacturing an electric wire or cable by silane-crosslinking the coating layer, first, the coating layer is formed by extruding silane-grafted chlorinated polyethylene. Subsequently, the electric wire or cable provided with the coating layer is wound into a drum shape, for example, and exposed to the outside air for a predetermined time. As a result, the silane-grafted chlorinated polyethylene of the coating layer is silane-crosslinked with moisture in the outside air.

Japanese Patent Publication No. 50-35540

In the case of electric wires and cables, in order to shorten the manufacturing time and to manufacture with high productivity, silane crosslinking is performed in a high temperature environment of about 100 ° C., for example, instead of a normal temperature environment. This is because, in a high temperature environment, the silane crosslinking reaction is accelerated as compared with a normal temperature environment, and the time required for silane crosslinking can be shortened.

However, when a coating layer made of silane-grafted chlorinated polyethylene is crosslinked with silane in a high temperature environment, the coating layer may be deformed. That is, the silane-grafted chlorinated polyethylene before crosslinking constituting the coating layer cannot sufficiently exhibit rubber elasticity in a high temperature environment, and therefore, in a high temperature environment, the silane-crosslinked silane-grafted chlorinated polyethylene is wound with a wire or cable wound in a drum shape. The cover layer is crushed and deformed by the weight and tension of the cable. As a result, the coating layer is silane-crosslinked in a deformed state, and the appearance of the surface is significantly impaired.

An object of this invention is to provide the silane graft | grafting composition which suppresses the deformation | transformation by heating.

A silane graft composition according to an embodiment of the present invention includes a silane-grafted chlorinated polyethylene obtained by graft-polymerizing a silane compound to chlorinated polyethylene;
And silane-grafted polyethylene obtained by graft-polymerizing a silane compound to polyethylene.

A method for producing a silane graft composition according to another embodiment of the present invention includes a step of forming a silane-grafted chlorinated polyethylene by graft-polymerizing a silane compound to chlorinated polyethylene;
Forming a silane-grafted polyethylene by graft polymerizing a silane compound to polyethylene;
Mixing the silane-grafted chlorinated polyethylene and the silane-grafted polyethylene.

The electric wire by other embodiment of this invention is equipped with the insulating layer formed from the crosslinked material which the said silane graft | grafting composition bridge | crosslinked.

A cable according to another embodiment of the present invention includes a jacket layer formed from a cross-linked product in which the silane graft composition is cross-linked.

According to one embodiment of the present invention, a silane graft composition that suppresses deformation due to heating can be provided.

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 a cross-sectional view showing a schematic structure of an electric wire according to an embodiment of the present invention. FIG. 3 is an explanatory view showing a grafting process using a single screw extruder in the example. FIG. 4 is an explanatory view showing the production of the cable in the example. FIG. 5 is an explanatory diagram showing a process of a heat deformation test in the example.

According to the study by the present inventors, it has been found that silane-grafted chlorinated polyethylene is a rubber material and is easily deformed by heating. Therefore, in order to suppress the deformation, a plastic material may be mixed. Plastic materials have more crystal components (high crystallinity) and higher melting points than rubber materials, and are not easily deformed by heating even if they are uncrosslinked. Therefore, the plastic material can impart heat deformation resistance to the rubber material.

Furthermore, the present inventors have conducted research on plastic materials and found that polyethylene (silane-grafted polyethylene) is suitable as a mixed material among plastic materials. Polyethylene can be graft-polymerized with a silane compound in the same manner as chlorinated polyethylene, and can be crosslinked with silane. That is, silane-grafted polyethylene is mixed with silane-grafted chlorinated polyethylene and reacted with moisture, whereby these can be integrally crosslinked with silane. Therefore, according to polyethylene, even when mixed with chlorinated polyethylene, a degree of crosslinking equivalent to that when chlorinated polyethylene alone is silane-crosslinked can be obtained without reducing the degree of crosslinking of the mixture.

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 graft composition The silane graft composition contains silane-grafted chlorinated polyethylene and silane-grafted polyethylene.

(Silane-grafted chlorinated polyethylene)
Silane-grafted chlorinated polyethylene is obtained by mixing chlorinated polyethylene, silane compound (silane coupling agent), and peroxide, and grafting the silane compound to chlorinated polyethylene in the presence of peroxide. It is. Silane graft chlorinated polyethylene has a silane group derived from the graft polymerized silane compound in the molecular chain. When the silane-grafted chlorinated polyethylene is brought into contact with water, the silane group in the molecular chain is hydrolyzed to become a silanol group, and the silanol groups are dehydrated and condensed to form a crosslinked structure, thereby silane crosslinking.

The chlorinated polyethylene is 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 not particularly limited, but from the viewpoint of setting the grafting rate of the silane compound and the degree of crosslinking when crosslinked to a desired range, for example, 25% to 45% is typical. Yes, 30% to 40% is more typical.

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-polymerized 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-polymerized to chlorinated polyethylene, and examples thereof include a vinyl group, a methacryl group, and an acrylic group. Among these, a vinyl group is typical as the unsaturated bond group. This is because a silane compound having a vinyl group (hereinafter also referred to as vinylsilane) has been widely used so far and can be suitably graft-polymerized to chlorinated polyethylene.

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.

As the silane compound, vinylsilane such as trimethoxyvinylsilane or triethoxyvinylsilane can be typically used.

The amount of silane compound graft polymerized to chlorinated polyethylene, that is, the amount of silane compound to be blended with chlorinated polyethylene is the degree of crosslinking of the final molded product (eg, insulation layer or sheath), or when crosslinked. The reaction conditions may be appropriately changed depending on the reaction conditions (for example, temperature and time). Specifically, the compounding amount of the silane compound is typically 0.1 parts by mass or more and 10 parts by mass or less, more typically 1.0 parts by mass or more and 5 parts by mass with respect to 100 parts by mass of the chlorinated polyethylene. 0 parts by mass or less. If the blending amount is less than 0.1 parts by mass, the amount of silane compound to be graft-polymerized decreases, so that there is a possibility that a sufficient degree of crosslinking cannot be obtained when the silane graft composition is crosslinked with silane. On the other hand, if the amount exceeds 10 parts by mass, slippage may occur between the material and the screw when the chlorinated polyethylene and the silane compound are graft-polymerized while kneading, and the biting property may be lowered. In addition, when the silane compound is graft-polymerized, there is a risk of early crosslinking (unintended crosslinking reaction). According to the early cross-linking, the local cross-linking proceeds in the silane graft composition, so that foreign matters (tubs) are formed due to the cross-linking, and irregularities are generated on the surface of the molded body. In other words, the appearance of the insulating layer and the sheath becomes poor due to the early crosslinking.

The peroxide is for graft polymerization of a silane compound on 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-polymerized to chlorinated polyethylene. Thus, the peroxide generates oxy radicals and causes graft polymerization 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 typical to use an organic peroxide having a one-minute half-life temperature of 120 ° C. or higher and 200 ° C. or lower 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. Specifically, the amount of peroxide (for example, dicumyl peroxide) blended in chlorinated polyethylene is x ₁ , and the amount of silane compound (for example, trimethoxyvinylsilane) blended in chlorinated polyethylene is changed. when the y _1, the ratio of the amount of peroxide to silane compound (x 1 _{/ y} ₁₎ is typically such that about 0.01, may be changed the amount of peroxide.
When the ratio x ₁ / y ₁ is excessively smaller than 0.01, the peroxide is excessively decreased with respect to the silane compound, so that the silane compound may not be efficiently graft-polymerized.
When the ratio x ₁ / y ₁ is excessively larger than 0.01, a large amount of peroxides and a large amount of radicals are generated, so that early cross-linking occurs and irregularities are generated on the surface of the insulating layer or the sheath, resulting in an appearance. There is a risk of failure.

(Silane-grafted polyethylene)
Silane-grafted polyethylene is obtained by mixing polyethylene, a silane compound, and a peroxide, and graft-polymerizing the silane compound onto polyethylene in the presence of the peroxide. Silane-grafted polyethylene, like the above-mentioned silane-grafted chlorinated polyethylene, has a silane group derived from a silane compound in the molecular chain and crosslinks with silane by reaction with water.

The polyethylene is not particularly limited as long as it can graft-polymerize a silane compound. For example, high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or the like is used. it can. From the viewpoint of further improving the heat distortion resistance of the silane graft composition, polyethylene having a high density may be used. This is because polyethylene becomes difficult to be deformed by heating because the crystal component increases as the density increases. Specifically, the density is typically 0.90 g / ml or more. On the other hand, if the density is too high, the hardness of the silane graft composition is increased, which may impair the flexibility of the insulating layer and the sheath. Therefore, the upper limit value of the density is typically 0.95 g / ml or less.

As the silane compound to be graft-polymerized to polyethylene, those described above can be used. The amount of the silane compound graft-polymerized to polyethylene, that is, the blending amount of the silane compound to be blended with polyethylene is typically 0.1 parts by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of polyethylene. Typically, it is 1.0 part by mass or more and 3.0 parts by mass or less. When the blending amount is less than 0.1 parts by mass, the graft amount of the silane compound is decreased, and therefore there is a possibility that a sufficient degree of crosslinking cannot be obtained when the silane graft composition is crosslinked with silane. On the other hand, if it exceeds 5.0 parts by mass, there is a risk that early crosslinking (unintended crosslinking reaction) may occur when the silane compound is graft polymerized.

As the peroxide for graft polymerizing a silane compound to polyethylene, those described above can be used. The compounding amount of the peroxide may be appropriately changed according to the compounding amount of the silane compound. Specifically, when the blending amount of the peroxide blended with polyethylene is x ₂ and the blending amount of the silane compound blended with polyethylene is y ₂ , the ratio of the blending amount of the peroxide to the silane compound (x ₂ / It is preferable to change the amount of peroxide so that y ₂ ) is typically about 0.04.
When the ratio x ₂ / y ₂ is excessively smaller than 0.04, the peroxide is excessively decreased with respect to the silane compound, and thus the silane compound may not be efficiently graft-polymerized.
When the ratio x ₂ / y ₂ is excessively larger than 0.04, a large amount of peroxides and a large amount of radicals are generated, so that early crosslinking occurs, and irregularities are generated on the surfaces of the insulating layer and the sheath, resulting in an appearance. There is a risk of failure.

(Mixing ratio)
The silane graft composition of this embodiment contains silane graft chlorinated polyethylene and silane graft polyethylene, but the mixing ratio thereof is not particularly limited. Typically, silane-grafted chlorinated polyethylene and silane-grafted polyethylene are mixed so that the ratio of chlorinated polyethylene to polyethylene is 55:45 to 90:10. When the ratio of polyethylene is less than 10, the amount of silane-grafted polyethylene decreases, so that the silane-graft composition may be deformed under a high temperature or high pressure environment. If the ratio exceeds 45, the amount of silane-grafted polyethylene increases, so the hardness of the silane-graft composition increases, and the flexibility of the insulating layer and sheath may not be ensured.

(Other additives)
The silane graft composition of this embodiment contains silane-grafted chlorinated polyethylene and silane-grafted polyethylene, but may contain a silanol condensation catalyst as necessary. According to the silanol condensation catalyst, the reaction of silane crosslinking can be promoted, and the silane graft composition can be efficiently crosslinked.

As the silanol condensation catalyst, for example, a group II element such as magnesium or calcium, a group VIII element such as cobalt or iron, a metal element such as tin, zinc and titanium, or 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 cablate, lead naphthenate, zinc caprylate, naphthene Cobalt acid or the like can be used. As the amine compound, ethylamine, dibutylamine, hexylamine, pyridine and the like can be used. As the acid, 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.

In addition, silane graft compositions include plasticizers, antioxidants (including anti-aging agents), fillers such as carbon black, flame retardants, lubricants, copper damage discoloration inhibitors, crosslinking aids, stabilizers, and other An additive may be contained.

(2) Manufacturing method of silane graft composition As a manufacturing method of a silane graft composition, there exists a method of mixing chlorinated polyethylene and polyethylene and graft-polymerizing a silane compound to the mixture.
However, according to the study by the present inventors, it has been found that this method makes it difficult to uniformly graft-polymerize the silane compound to each of chlorinated polyethylene and polyethylene. This is presumably because the graft reactivity with the silane compound and the optimum conditions for graft polymerization are different between chlorinated polyethylene and polyethylene. If the graft polymerization cannot be performed uniformly, the grafting rate of the silane compound in the silane graft composition will not be uniform, resulting in variations. As a result, for example, unintended early crosslinking occurs when the silane compound is graft-polymerized, whereby local crosslinking occurs in the resulting silane graft composition, and a crosslinked product is formed as a foreign matter (tube). On the other hand, if the amount of the silane compound or peroxide is reduced in order to suppress premature crosslinking, the amount of silane compound that is graft-polymerized to the silane graft composition is reduced, so that the crosslinking when the silane graft composition is crosslinked. May become low.
As described above, when the silane compound is graft-polymerized to a mixture of chlorinated polyethylene and polyethylene, the grafting rate of the silane compound is biased between the two polymers, and accordingly, the silane graft composition has an early cross-linking or degree of cross-linking. Decrease may occur.

From this viewpoint, from the viewpoint of suppressing the early crosslinking of the silane graft composition and the decrease in the degree of crosslinking, the silane-grafted chlorinated polyethylene and the silane were obtained by graft-polymerizing the silane compound separately to each of chlorinated polyethylene and polyethylene. It has been found that silane graft compositions can be prepared by mixing with grafted polyethylene. Hereinafter, this manufacturing method will be specifically described.

(Silane grafting process of chlorinated polyethylene)
First, a silane compound is graft polymerized to chlorinated polyethylene. For example, dicumyl peroxide as a peroxide and a silane compound having a vinyl group (vinyl silane) are added to chlorinated polyethylene, followed by heating and kneading. Thereby, vinyl silane is graft-polymerized to chlorinated polyethylene in the presence of peroxide to form silane-grafted chlorinated polyethylene.

In the silane grafting step of chlorinated polyethylene, the silane compound may be blended in an amount of 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of chlorinated polyethylene. The amount of peroxide, x ₁ the amount of _peroxide, when the amount of the silane compound was y _1, the ratio (x 1 _{/ y} ₁₎ is suitably such that about 0.01 It is good to change. In the silane grafting step, for example, kneading may be performed using a kneading reaction apparatus such as a roll machine, an extruder, a kneader, a mixer, or an autoclave.

(Silane grafting process of polyethylene)
Moreover, a silane compound is graft-polymerized to polyethylene separately from the silane grafting step of chlorinated polyethylene. For example, dicumyl peroxide and vinyl silane are added as peroxides to polyethylene and kneaded by heating. Thereby, vinyl silane is graft-polymerized on polyethylene in the presence of peroxide to form silane-grafted polyethylene.
In the silane grafting step of polyethylene, a different kind of silane compound or peroxide from the silane grafting step of chlorinated polyethylene may be used.

In the polyethylene silane grafting step, the silane compound may be blended in an amount of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of polyethylene. The amount of peroxide, x ₂ the amount of _peroxide, when the amount of the silane compound was y _2, the ratio (x 2 _{/ y} ₂₎ is appropriately such that the order of 0.04 It is good to change.

(Mixing process)
The silane-grafted chlorinated polyethylene and the silane-grafted polyethylene obtained in the above-described steps are mixed so that, for example, the ratio of polyethylene to the total of chlorinated polyethylene and polyethylene is 10 or more and 45 or less. Thereby, the silane graft | grafting composition of this embodiment is obtained.

In this embodiment, each of chlorinated polyethylene and polyethylene is silane-grafted in separate steps. Thereby, each can be silane-grafted on optimal conditions (for example, the compounding quantity of a silane compound or a peroxide, etc.). And the silane graft | grafting composition obtained by mixing these has high crosslinking degree after making it bridge | crosslink while suppressing early bridge | crosslinking.

Specifically, since early crosslinking is suppressed in the silane graft composition, the degree of crosslinking before crosslinking is small, and the gel fraction before crosslinking is 30% or less. If the gel fraction before cross-linking exceeds 30%, the degree of premature cross-linking increases, so that it is difficult to extrude the silane graft composition and the processability may be reduced. Moreover, the generation | occurrence | production of the foreign material (tub) by early bridge | crosslinking increases, and there exists a possibility that the external appearance of the surface when a silane graft composition is extruded may be impaired.

The silane graft composition has a high degree of cross-linking after cross-linking, and the gel fraction after cross-linking is 60% or more. That is, the crosslinked product obtained by crosslinking the silane graft composition has a gel fraction of 60% or more. If the gel fraction after cross-linking is less than 60%, the cross-linking becomes insufficient, and therefore there is a possibility that mechanical properties such as a sheath formed from a cross-linked product cannot be ensured.

In the silane grafting step and the mixing step, for example, kneading may be performed using a kneading reaction apparatus such as a roll machine, an extruder, a kneader, a mixer, or an autoclave. Further, kneading conditions and grafting conditions (temperature, time, etc.) are not particularly limited.

(4) Cable Configuration Next, the cable 1 according to an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a schematic structure of a cable 1 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 crosslinked product obtained by crosslinking the silane graft composition. The sheath 12 is formed from a crosslinked product having a gel fraction of 60% or more, and has a high degree of crosslinking.

The cable 1 is manufactured as follows, for example. First, a copper wire is prepared as the conductor 10. And the resin composition containing ethylene propylene rubber is extruded so that the outer periphery of the conductor 10 may be coat | covered with an extruder, and the insulating layer 11 of predetermined thickness is formed. Subsequently, the sheath 12 is formed by extruding the silane graft 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 atmosphere of saturated water vapor at 60 ° C., for example, so that the silane graft composition forming the sheath 12 reacts with moisture to cause silane crosslinking.

<Effects of Embodiment of the Present Invention>
According to the present embodiment, the following one or more effects can be achieved.

(A) According to this embodiment, the silane graft composition contains silane graft chlorinated polyethylene and silane graft polyethylene. Since the silane-grafted polyethylene is made of polyethylene that has relatively high crystallinity and is not easily deformed by heating, heat-resistant deformation can be imparted to the silane-grafted composition. Therefore, according to the silane graft composition of the present embodiment, deformation due to heating is suppressed even when silane crosslinking is performed in a high-temperature environment in order to shorten the time for crosslinking treatment.

(B) According to this embodiment, the silane graft composition is obtained by graft-polymerizing a silane compound separately to each of chlorinated polyethylene and polyethylene, and mixing the obtained silane-grafted chlorinated polyethylene and silane-grafted polyethylene. It is formed with. By making the silane graft of chlorinated polyethylene and the silane graft of polyethylene into separate steps, each can be silane grafted under optimum conditions. Thereby, when the mixture of chlorinated polyethylene and polyethylene is silane-grafted, variation in grafting of the silane compound caused by the difference in graft reactivity can be suppressed. As a result, unintended early crosslinking that occurs during graft polymerization of the silane compound can be suppressed, and the degree of crosslinking when the silane graft composition is crosslinked can be increased.
Specifically, by suppressing early crosslinking, the degree of crosslinking before crosslinking of the silane graft composition can be made 30% or less in terms of gel fraction. Moreover, the crosslinking degree of the crosslinked material which bridge | crosslinked the silane graft composition can be made high with 60% or more in a gel fraction.

(C) According to the present embodiment, silane-grafted chlorinated polyethylene and silane-grafted polyethylene are mixed so that the ratio of chlorinated polyethylene to polyethylene is 55:45 to 90:10. By setting the ratio of polyethylene to 10 or more, higher heat distortion resistance of the silane graft composition can be ensured. Moreover, it can suppress that the hardness of a silane graft | grafting composition becomes too high because the ratio of polyethylene shall be 45 or less.

(D) According to the present embodiment, since the early crosslinking is suppressed in the silane graft composition, an excessive increase in viscosity due to the early crosslinking is suppressed. Therefore, since the silane graft composition can be stably extruded, a molded body such as a sheath can be formed with less dimensional variation. Moreover, since the formation of foreign matters (tubs) due to early crosslinking can be suppressed, a molded article having a good surface appearance can be formed.

(E) According to this embodiment, the cable includes a sheath formed from a crosslinked product obtained by crosslinking the silane graft composition. Since the silane graft composition is excellent in heat distortion resistance, the sheath formed therefrom is less deformed when crosslinked in a high temperature environment, and is prevented from being crushed. In addition, since the silane graft composition has a high degree of grafting of the silane compound and is uniform, the sheath has a high degree of crosslinking of 60% or more in terms of gel fraction. Moreover, since the early crosslinking | crosslinking is suppressed, the sheath has few fluctuation | variations of an outer diameter, and the surface external appearance is favorable.

<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 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 includes a stranded wire obtained by twisting two or more electric wires. Also good.

Moreover, although the above-mentioned embodiment demonstrated the case where a silane graft composition was used as a coating layer (sheath 12) of the cable 1, it is not limited to this. A silane graft | grafting composition can also be used for the insulating layer 11 of the electric wire 2 as shown, for example in FIG. In this case, as in the case of forming the sheath 12 in the above-described embodiment, the insulating layer 11 is formed by extruding the silane graft composition on the outer periphery of the conductor 11, and the insulating layer 11 is brought into contact with water for silane crosslinking. Good.

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.
Low density polyethylene (density d: 0.922 g / ml, MFR: 2.3 g / 10 min): “Evolue SP2030” manufactured by Prime Polymer 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.
Polyethylene wax (molecular weight: 2800): “High Wax NL-200” manufactured by Mitsui Chemicals, Inc.
・ Peroxide (Dicumyl peroxide): “DCP” manufactured by NOF Corporation
Silane compound (vinyltrimethoxysilane): “KBM-1003” manufactured by Shin-Etsu Chemical Co., Ltd.
・ Plasticizer (Process oil): “NP-24” manufactured by Idemitsu Kosan Co., Ltd.
・ Sulfur-based 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.
・ 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 (ethylenebisoleic acid amide): “Sripac-O” manufactured by Nippon Kasei Co., Ltd.
Silanol condensation catalyst (dioctyltin dineodecanoate): “Neostan U-830” manufactured by Nitto Kasei Co., Ltd.

(1) Preparation of silane graft composition <Examples 1 to 5>
In Examples 1 to 5, graft materials A and B were prepared by grafting using the materials described above with the formulation shown in Table 1, and then graft materials A and grafts with the formulation shown in Table 2. A silane graft composition was prepared by mixing material B with other additives. This will be specifically described below.

(Grafting of chlorinated polyethylene)
First, prior to grafting, chlorinated polyethylene was pretreated.
Specifically, as shown in Table 1, 6 parts by mass of hydrotalcite as a stabilizer and 6 parts of epoxidized soybean oil as a stabilizer with respect to 100 parts by mass of powdered chlorinated polyethylene. Part by mass and 3 parts by mass of polyethylene wax as a lubricant were added and kneaded using an 8-inch roll machine. At this time, the surface temperature of the roll was set to 100 ° C., and the kneading time was kneaded for 5 minutes after the addition of the stabilizer and the like was completed. Thereafter, the sheet obtained by kneading was pelletized into a 5 mm square shape to obtain pellets containing chlorinated polyethylene. In order to prevent adhesion between the pellets, 1 part by mass of talc was applied to the pellets.

Subsequently, grafting was performed on the obtained pellets.
Specifically, the obtained pellets were sufficiently impregnated with a silane mixture in which a peroxide was dissolved in a silane compound. At this time, as described in Table 1, the pellet was impregnated with a silane mixture so that the peroxide was 0.03 part by mass and the silane compound was 3 parts by mass with respect to 100 parts by mass of the chlorinated polyethylene. It was. Then, the pellet impregnated with the silane mixture was put into the cylinder 103a from the hopper 101 of the single screw extruder 100 shown in FIG. 3, and sent out from the cylinder 103a to the cylinder 103b by the rotation of the screw 102. At this time, the pellets were heated by the

cylinders

103a and 103b and softened and kneaded to graft polymerize the silane compound to the chlorinated polyethylene. This formed the silane graft | grafting chlorinated polyethylene. Thereafter, the silane-grafted chlorinated polyethylene was fed to the head portion 104 of the extruder 100, and a strand 20 (length: 150 cm) of the silane-grafted chlorinated polyethylene 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. Thereafter, the strand 20 was pelletized with the pelletizer 108 to obtain a pellet-shaped graft material A.
In the grafting process, a single screw extruder 100 having a screw diameter of 40 mm 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. Moreover, the rotation speed of the screw 102 was 20 rpm (extrusion amount about 120 g / min), and the screw 102 was made into a full flight shape. Further, a die having a hole diameter of 5 mm and three holes was used as the die 105.

(Polyethylene grafting)
The grafting process of polyethylene was performed similarly to the grafting process of chlorinated polyethylene.
Specifically, polyethylene pellets were sufficiently impregnated with silane mixture. At this time, as shown in Table 1, the pellet was impregnated with a silane mixture so that the peroxide was 0.06 parts by mass and the silane compound was 1.5 parts by mass with respect to 100 parts by mass of polyethylene. It was. Then, the pellets impregnated with the silane mixture are put into a single screw extruder 100 shown in FIG. 3, and a silane-grafted polyethylene is formed by grafting, and the strands are pelletized to form pellet-like grafts. Material B was obtained.

(Preparation of catalyst masterbatch)
Subsequently, separately from the graft material A and the graft material B, a catalyst master batch containing a silanol condensation catalyst was prepared.
Specifically, hydrotalcite is 6 parts by mass, epoxidized soybean oil is 6 parts by mass, polyethylene wax is 3 parts by mass, and silanol condensation catalyst with respect to 100 parts by mass of powdered chlorinated polyethylene. 2 parts by mass of dioctyltin dineodecanoate as a mixture was added and kneaded using an 8-inch roll machine. At this time, the surface temperature of the roll was set to 100 ° C., and the kneading was carried out for 3 minutes after the silanol condensation catalyst was added. Then, the sheet | seat which consists of kneaded materials was pelletized in the shape of 5 square mm, and the catalyst masterbatch was prepared.

(Mixing process)
Subsequently, graft material A (silane-grafted chlorinated polyethylene), graft material B (silane-grafted polyethylene), and other additives were kneaded by an 8-inch roll machine with the formulation shown in Table 2. In Examples 1 to 5, as shown in Table 2, the ratio of chlorinated polyethylene to polyethylene was adjusted by appropriately changing the mixing ratio of graft material A and graft material B. As additives, 10 parts by weight of process oil as a plasticizer, 0.08 parts by weight of a sulfur-based antioxidant, and amine-based oxidation with respect to a total of 100 parts by weight of chlorinated polyethylene and polyethylene. 1.5 parts by mass of an inhibitor, 3 parts by mass of antimony trioxide as a flame retardant, 40 parts by mass of FEF carbon black as a carbon black, 1 part by mass of ethylene bisoleic acid amide as a lubricant, Was added respectively. Further, at the time of kneading, the surface temperature of the roll was set to 130 ° C., and all the additives were added, and kneading was performed for 5 minutes.

Finally, 2.5 parts by mass of the catalyst master batch was added to the kneaded material such as graft material A and graft material B and dry blended to prepare the silane graft compositions of Examples 1 to 5.

<Example 6>
In Example 6, a silane graft composition was prepared using a graft material C obtained by previously mixing chlorinated polyethylene and polyethylene and grafting the mixture.
Specifically, as shown in Table 1, 70 parts by mass of chlorinated polyethylene, 30 parts by mass of polyethylene, and other additives were mixed and kneaded using an 8-inch roll machine. At this time, the surface temperature of the roll was set to 100 ° C., and kneading was performed for 5 minutes after the addition of the additives and the like was completed.
Thereafter, the sheet obtained by kneading was pelletized into a 5 mm square shape. The obtained pellet is impregnated with a silane mixture containing 0.03 parts by mass of a peroxide and 3 parts by mass of a silane compound, and the silane compound is graft polymerized using the single screw extruder 100 shown in FIG. Graft material C was obtained. Subsequently, as described in Table 2, the silane graft composition of Example 6 was prepared by mixing the graft material C, other additives, and a catalyst master batch.

<Example 7>
In Example 7, a silane graft composition was prepared in the same manner as in Example 6 except that the graft material D shown in Table 1 was used instead of the graft material C used in Example 6. The graft material D was prepared in the same manner as the graft material C, except that the amount of the silane compound and peroxide blended when the silane compound was graft polymerized to a mixture of chlorinated polyethylene and polyethylene was changed.

<Comparative Example 1>
In Comparative Example 1, as described in Table 2, silane graft compositions were prepared in the same manner as in Examples 1 to 5 except that the graft material A shown in Table 1 was used.

(2) Production of Cable Next, the cables of Examples 1 to 7 and Comparative Example 1 were produced by extruding the silane graft compositions of Examples 1 to 7 and Comparative Example 1.
Specifically, a copper conductor (outer diameter 3.7 mm) 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 shown in FIG. The rubber 1) is extruded to form the insulating layer 11 having a thickness of 1.0 mm, and the sheath 12 having a thickness of 1.7 mm is formed by extruding the silane graft composition described above on the outer periphery of the insulating layer 11. Was made. Thereafter, the cable 1 was stored in a constant temperature and humidity chamber having a temperature of 60 ° C. and a relative humidity of 95% for 24 hours to crosslink the sheath 12.
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 neck 109 was 140 ° C., the temperature of the crosshead portion 110 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 shape of the screw 102 was a full flight shape.

(3) Evaluation method The prepared silane graft composition and the produced cable were evaluated by the following methods.

(Heat-resistant deformation)
In order to evaluate the heat distortion resistance of the silane graft composition, a heat deformation test was performed on the cable immediately after the silane graft composition was extruded (the cable before the crosslinking treatment). This heat deformation test simulated the phenomenon that the surface of the cable is deformed when the cable wound in a drum shape is crosslinked with silane in a high temperature environment. Specifically, the heat deformation test was performed by the following method.
First, a sample having a length of 30 mm was cut out from the cable before the crosslinking treatment. Subsequently, using a heat deformation tester (TM-1515 manufactured by Ueshima Seisakusho Co., Ltd.), as shown in FIG. 5, the sample S was heat deformed under the conditions of a temperature of 60 ° C., a load of 2 N, and 24 hours. A test was conducted. And the width | variety of the strip-shaped deformation | transformation trace (hatching area | region in FIG. 5) which arose on the surface of the sample S by heat deformation was measured, and the heat-resistant deformation property of the silane graft composition was evaluated by the magnitude | size of the width | variety. A smaller width of the deformation mark indicates that the silane graft composition is less likely to be heat-deformed and has better heat distortion resistance. In this example, with reference to the deformation width of 1.84 mm of Comparative Example 1 (silane-grafted chlorinated polyethylene alone), when it is 1.84 mm or more, it is judged that the heat resistance deformation property is poor, and the deformation width is “X”. If it is less than 1.84 mm and more than 1.00 mm, it is judged that the heat distortion resistance has been improved, and if the deformation width is 1.00 mm or less, it is judged that the heat distortion resistance has been further improved. “◎”. In addition, since the heat deformation test differs depending on the shape of the cable, the length of the cable wound in a drum shape, the temperature at the time of crosslinking, and the like, the above test conditions are an example.

(Gel fraction before crosslinking)
In order to evaluate the degree of early crosslinking of the silane graft composition, the gel fraction before crosslinking of the silane graft composition was measured. The gel fraction before cross-linking indicates quantitatively the degree to which early cross-linking has progressed during the preparation of the silane graft composition, and the higher the gel fraction before cross-linking indicates that pre-cross-linking has progressed. . Specifically, the gel fraction before crosslinking was measured by the following method. First, 0.5 g of a sample was taken from the silane graft composition, and this sample was placed 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 before cross-linking exceeds 50% is indicated as “X”, the case where the gel fraction is 50% or less and over 30% is indicated as “◯”, and the case where it is 30% or less is indicated as “「 ”.

(Gel fraction after crosslinking)
In order to measure the gel fraction after the silane graft composition was cross-linked, a 0.5 g sample was taken from the sheath 12 of the cable 1 and the gel fraction was calculated in the same manner as described above. In this example, the case where the gel fraction after crosslinking is 60% or more is “◎”, the case where it is less than 60% and 50% or more is “◯”, and the case where it is less than 50% is “×”.

(hardness)
In order to evaluate the flexibility of the cross-linked sheath, the hardness of JIS A was measured for the cross-linked sheath. In this example, the case where the hardness exceeds 95 is indicated as “x”, the case where the hardness is 95 or less and over 90 is indicated as “◯”, and the case where the hardness is 90 or less is indicated as “◎”.

(Comprehensive evaluation)
As the overall evaluation, “◎” indicates that all evaluations are “◎”, “◯” indicates that there is at least one ○, and “×” indicates that there is at least one ×.

(4) Evaluation results The evaluation results are listed in Table 2. As shown in Table 2, Examples 2 to 4 had an overall evaluation of ◎, Examples 1 and 5 to 7 had an overall evaluation of ◯, and Comparative Example 1 had an overall evaluation of ×.

Comparative Example 1 is an example in which only silane-grafted chlorinated polyethylene is blended. In Comparative Example 1, as shown in Table 2, the deformation width by the heat deformation test was 1.84 mm, and it was confirmed that the heat deformation resistance was poor.
On the other hand, in Examples 1 to 7, it was confirmed that the deformation width can be reduced as compared with Comparative Example 1 by mixing silane-grafted polyethylene with silane-grafted chlorinated polyethylene. From this, it was found that by adding silane-grafted polyethylene, the silane-grafted chlorinated polyethylene can be imparted with heat distortion resistance, and deformation under a high temperature environment can be suppressed.

Examples 1 to 5 are examples in which the mixing ratio of the graft material A and the graft material B was changed to change the mixing ratio of the silane-grafted chlorinated polyethylene and the silane-grafted polyethylene. According to Examples 1 to 5, as shown in Table 2, it is shown that as the blending amount of the graft material B is increased (the ratio of polyethylene is increased), the deformation width in the heat deformation test is further decreased. Yes. Particularly, according to Examples 2 to 5, it is shown that the deformation width can be suppressed to 1.00 mm or less by setting the ratio of polyethylene to the total of chlorinated polyethylene and polyethylene to 10 or more. From this, it was found that the polyethylene ratio should be 10 or more from the viewpoint of reducing the deformation width.

On the other hand, according to Examples 1 to 5, it is shown that the hardness of the sheath after crosslinking increases as the ratio of polyethylene increases. When the hardness is higher than 90, the flexibility of the cable is impaired. From the viewpoint of securing the flexibility of the cable by setting the hardness to 90 or less, it has been found that the ratio of polyethylene should be 45 or less.

According to Example 3 and Example 6, it was confirmed that the ratio of chlorinated polyethylene and polyethylene was the same, and that the heat distortion resistance, the gel fraction before crosslinking, and the hardness were all good. However, it was found that the gel fraction after crosslinking was 73% in Example 3 and 57% in Example 6, and that Example 3 was higher than Example 6. That is, it was confirmed that Example 3 had a higher degree of cross-linking of the sheath than Example 6 and was excellent in mechanical strength. The reason is presumed as follows.
In Example 6, a mixture of chlorinated polyethylene and polyethylene was grafted,
It is considered that the gel fraction after crosslinking was lowered because each could not be uniformly grafted, and in particular, the grafting of polyethylene could not be sufficiently performed.
On the other hand, in Example 3, the thing which was able to raise the gel fraction after bridge | crosslinking by grafting each of chlorinated polyethylene and polyethylene separately on optimal conditions can be considered.

According to Example 3 and Example 7, it was confirmed that the ratio of chlorinated polyethylene and polyethylene was the same, and that the heat resistance, gel fraction after crosslinking, and hardness were all good. However, it was found that the gel fraction before crosslinking was 26% in Example 3 and 62% in Example 7, and that Example 7 was higher than Example 3. That is, in Example 7, it was confirmed that early cross-linking progressed more than Example 3. In Example 7 in which early crosslinking progressed, it was difficult to extrude the silane graft composition, and the tendency of the outer diameter of the sheath to fluctuate was confirmed. Further, it was confirmed that foreign matters (tubs) were formed by the early cross-linking, and foreign matters appeared on the surface of the sheath formed by extruding the silane graft composition and the appearance was liable to be impaired. The reason why the early crosslinking progressed in Example 7 was that when the mixture of chlorinated polyethylene and polyethylene was grafted, the ratio of peroxide to silane compound was increased as shown in Table 1. Conceivable.

<Representative Embodiment of the Present Invention>
In the following, exemplary embodiments of the present invention are listed.

[1] A silane graft composition according to an embodiment of the present invention includes a silane-grafted chlorinated polyethylene obtained by graft-polymerizing a silane compound to chlorinated polyethylene,
And silane-grafted polyethylene obtained by graft-polymerizing a silane compound to polyethylene.

[2] In the silane graft composition of [1], typically, the gel fraction before crosslinking is 30% or less, and the gel fraction after crosslinking is 60% or more.

[3] In the silane graft composition according to [1] or [2], typically, the silane graft chlorination is performed so that a ratio of the chlorinated polyethylene to the polyethylene is 55:45 to 90:10. Contains polyethylene and the silane-grafted polyethylene.

[4] In the silane graft compositions of [1] to [3], typically, the silane compound has a vinyl group.

[5] A method for producing a silane graft composition according to an embodiment of the present invention includes a step of forming a silane-grafted chlorinated polyethylene by graft-polymerizing a silane compound to chlorinated polyethylene;
Forming a silane-grafted polyethylene by graft polymerizing a silane compound to polyethylene;
Mixing the silane-grafted chlorinated polyethylene and the silane-grafted polyethylene.

In the method for producing a silane graft composition according to [5], typically, in the mixing step, the silane graft chlorinated polyethylene and the silane graft polyethylene are used, and the ratio of the chlorinated polyethylene and the polyethylene is 55: Mix to 45-90: 10.

[6] An electric wire according to an embodiment of the present invention includes an insulating layer formed from a crosslinked product obtained by crosslinking the silane graft composition of [1] to [4].

[7] A cable according to an embodiment of the present invention includes a jacket layer formed from a crosslinked product obtained by crosslinking the silane graft composition of [1] to [4].

The present invention can be applied to a silane graft composition used as a material for forming a coating layer such as an electric wire insulation layer or a cable sheath layer (sheath).

1 Cable 2 Electric wire 10 Conductor 11 Insulating layer 12 Outer layer (sheath)

Claims

A silane-grafted chlorinated polyethylene obtained by graft-polymerizing a silane compound to chlorinated polyethylene;
A silane graft composition comprising: a silane graft polyethylene obtained by graft-polymerizing a silane compound to polyethylene.
The silane graft composition according to claim 1, comprising the silane-grafted chlorinated polyethylene and the silane-grafted polyethylene so that a ratio of the chlorinated polyethylene to the polyethylene is 55:45 to 90:10.
The silane graft composition according to claim 1 or 2, wherein the silane compound has a vinyl group.
Forming a silane-grafted chlorinated polyethylene by graft polymerizing a silane compound to the chlorinated polyethylene;
Forming a silane-grafted polyethylene by graft polymerizing a silane compound to polyethylene;
And a step of mixing the silane-grafted chlorinated polyethylene and the silane-grafted polyethylene.
The silane-grafted chlorinated polyethylene and the silane-grafted polyethylene are mixed in the mixing step so that a ratio of the chlorinated polyethylene and the polyethylene is 55:45 to 90:10. The manufacturing method of silane graft | grafting composition of this.
An electric wire comprising an insulating layer formed from a crosslinked product of the silane graft composition according to any one of claims 1 to 3.
A cable comprising a jacket layer formed from a crosslinked product of the silane graft composition according to any one of claims 1 to 3.