JP2018141064A - Silane graft resin composition, electric wire and cable - Google Patents

Abstract

An object of the present invention is to provide a silane graft resin composition having a good appearance for covering materials of electric wires and cables. A silane-grafted resin composition is extruded so as to cover the outer periphery of a conductor, and thereafter, the silane-grafted resin composition is reacted with moisture to crosslink with silane. This silane-grafted resin composition has a silane-grafted resin obtained by performing a graft reaction of a silane compound with a non-halogen resin using a peroxide, and an additive. The silane compound has an unsaturated bond group and a hydrolyzable silane group, and the unsaturated bond group is a methacryl group. The compounding ratio (Rc) of the silane coupling agent and the peroxide is in the range of 1.5 to 20. Thereby, the localization of the graft portion can be reduced, and in the localized graft portion, an undesired crosslinking reaction due to condensation of silanes can be suppressed. The appearance of the insulating layer 11) can be improved. [Selection diagram] Fig. 1

Description

  The present invention relates to a silane graft resin composition, an electric wire and a cable.

  The cable includes an electric wire and a covering layer (sheath layer) provided on the outer periphery of the electric wire. The electric wire includes a conductor and an insulating layer provided on the outer periphery of the conductor, and the jacket layer (sheath layer) is provided on the outer periphery of the insulating layer.

  In coating materials such as the cable jacket and cable insulation layers, a cross-linking treatment that chemically bonds the polymers of the coating material is performed to improve various properties including heat resistance. Often applied. As the crosslinking method, there is a silane crosslinking method in which a silane compound (so-called silane coupling agent) is chemically bonded to a polymer molecule in advance and the crosslinking is advanced using the silane compound bonded to the polymer.

  For example, Patent Document 1 discloses a technique for forming a coating layer on the outer periphery of a conductor using a resin composition containing a silane-grafted uncrosslinked polyolefin.

JP 2014-105257 A

  The present inventor has been engaged in research and development of coating materials such as cable jacket layers and electric wire insulation layers, and has examined non-halogen resin as a coating material polymer and examined effective crosslinking technology. ing. In the process, it has been found that depending on the combination of the non-halogen resin and the silane compound, appearance defects (unevenness on the surface) may occur when the cable is covered. In particular, when a flame retardant is kneaded in the resin composition, poor appearance tends to occur.

  This invention is made | formed in view of the said subject, and it aims at providing the silane graft | grafting resin composition for the coating | covering material of the electric wire or cable which has a favorable external appearance.

(1) A silane graft resin composition of one embodiment of the present invention includes a silane graft resin obtained by graft-reacting a silane compound with a non-halogen resin using a peroxide, and an additive. Has an unsaturated bond group and a hydrolyzable silane group, and the unsaturated bond group is a methacryl group, and the blending ratio of the silane coupling agent and the peroxide represented by the following formula: (Rc) is in the range of 1.5-20.
Rc = (WS / MS) / (2αWO / MO)
Where WS is the amount of silane coupling agent (g), WO is the amount of peroxide (g), MS is the molecular weight of the silane coupling agent, MO is the molecular weight of the peroxide, and α is the peroxide. The number of oxygen-oxygen bonds per molecule.

  (2) The silane graft resin composition preferably has a gel fraction after crosslinking of 50% or more.

  (3) The non-halogen resin preferably contains an ethylene-vinyl acetate copolymer.

  (4) The silane compound is preferably 3-methacryloxypropyltrimethoxysilane or 3-methacryloxypropyltriethoxysilane.

  (5) The additive is preferably a flame retardant.

  (6) It is preferable that the electric wire of 1 aspect of this invention is equipped with the insulating layer formed from the crosslinked material of the silane graft composition in any one of said (1)-(5).

  (7) The cable of one embodiment of the present invention preferably includes a jacket layer formed from a crosslinked product of the silane graft composition according to any one of (1) to (5) above.

  By using the silane graft resin composition of one embodiment of the present invention as a coating material for electric wires and cables, the appearance of the electric wires and cables can be improved.

It is sectional drawing which shows the structure of an electric wire. It is sectional drawing which shows the structure of a cable. It is the schematic which shows the mode of the graft process using a single screw extruder. It is the schematic which shows the mode of production of a cable.

(Embodiment)
The electric wires and cables are covered with a coating material, and the coating material is made of a resin obtained by crosslinking the silane graft resin composition.

(1) Silane graft resin composition The silane graft resin composition has a silane graft resin and an additive.

(Silane graft resin)
The silane graft resin is obtained by mixing a resin (base polymer, polymer), a silane coupling agent, and a peroxide, and graft-polymerizing the silane coupling agent to the resin in the presence of the peroxide. .

  Therefore, the silane graft resin has a silane group derived from the graft-polymerized silane coupling agent in the molecular chain. When the silane graft resin comes into contact with water, the silane group in the molecular chain is hydrolyzed to form a silanol group, and the silanol groups are dehydrated and condensed to form a crosslinked structure (silane crosslinking). In addition, although there exists the method performed by adding energy, such as a heat | fever and an electron beam, as a crosslinking process of resin, this method requires a large-scale installation and a great deal of energy. On the other hand, the silane cross-linking method does not require large-scale equipment and enormous energy, and is advantageous in terms of economy and environment.

  In this embodiment, a non-halogen resin is used as the resin. Non-halogen resins are resins that do not contain halogen elements in their molecular structure, and do not generate toxic gases such as dioxins during combustion. Therefore, they are suitable for use as coating materials for electric wires and cables. As the non-halogen resin, polyethylene is representative, but from the viewpoint of oil resistance and flame resistance, which are often required as a coating material for electric wires and cables, a polyolefin-based resin containing a vinyl acetate group, specifically It is preferable to use an ethylene-vinyl acetate copolymer (EVA).

  The ethylene-vinyl acetate copolymer (EVA) is a copolymer of ethylene and vinyl acetate (VA). The amount of VA in the polymer is preferably about 10 wt% to 60 wt% in consideration of compatibility with a silane coupling agent containing a methacryl group described later and workability such as stickiness. As the resin, a mixture of a polyolefin-based resin containing a vinyl acetate group such as EVA and other non-halogen resins may be used.

  The silane coupling agent has an unsaturated bond group and a hydrolyzable silane group. A silane coupling agent introduces a silane group into a resin by graft polymerization to a non-halogen resin with an unsaturated bond group. In the silane graft resin, when it comes into contact with water, hydrolyzable silane groups are hydrolyzed to become silanol groups, and these silanol groups are dehydrated and condensed to form a crosslinked structure.

Here, in the present embodiment, the unsaturated bonding group of the silane coupling agent, having a methacryl group _{(H 2 C = C (CH} 3) -CO-). As described above, the grafting using the silane coupling agent having a methacryl group can reduce localization of the graft portion. As a result, undesired cross-linking reaction (cross-linking reaction before cross-linking treatment) due to condensation of silanes can be suppressed in the localized graft portion. Thereby, the appearance defect at the time of using as a coating | covering material of an electric wire or a cable can be reduced.

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

  As the silane coupling agent, 3-methacryloxypropyltrimethoxysilane or 3-methacryloxypropyltriethoxysilane can be preferably used. Other silane coupling agents will be described later.

  The blending amount of the silane coupling agent is preferably 0.1 parts by mass or more and 10 parts by mass or less, and more preferably 1.0 part by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the non-halogen resin. When the blending amount is less than 0.1 parts by mass, the amount of silane coupling agent to be graft polymerized is small, 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, when the amount exceeds 10 parts by mass, local crosslinking is likely to proceed, and there is a possibility that irregularities are generated on the surface of the molded body.

  The peroxide is for graft polymerization of a silane coupling agent to a non-halogen resin. Specifically, the peroxide generates oxy radicals by thermal decomposition. The oxy radical generates a radical of a non-halogen resin (for example, EVA) by extracting hydrogen in the non-halogen resin (for example, EVA). And a non-halogen resin (for example, EVA) reacts with the unsaturated bond group (methacryl group etc.) which a silane coupling agent has, and a silane graft resin (for example, silane graft EVA) is produced.

  As the peroxide, for example, an organic peroxide can be used. Organic peroxide has a high hydrogen abstraction ability. Specific peroxide will be described later.

  Moreover, it is preferable to adjust the compounding ratio (Rc) of a silane coupling agent and a peroxide so that it may become an appropriate range (for example, 1.5-20).

The compounding ratio (Rc) of the silane coupling agent and the peroxide is represented by the following formula.
Rc = (WS / MS) / (2αWO / MO)
WS is the compounding amount (g) of the silane coupling agent, WO is the compounding amount of the peroxide (g), MS is the molecular weight of the silane coupling agent, MO is the molecular weight of the peroxide, and α is one molecule of the peroxide. Number of oxygen-oxygen bonds per unit.

  By such adjustment, the amount of radicals generated by the decomposition of the peroxide can be secured, and the unintended crosslinking reaction during the grafting process can be suppressed while the grafting reaction is sufficiently advanced. Details will be described later.

(Additive)
The silane graft resin composition may contain the following additives in addition to the silane graft resin.

<Silanol condensation catalyst>
The silanol condensation catalyst has a role of accelerating the silane crosslinking reaction and efficiently crosslinking the silane graft resin composition.

  As the silanol condensation catalyst, for example, group II elements such as magnesium and calcium, group VIII elements such as cobalt and iron, metal elements such as tin, zinc and titanium, and metal compounds 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.

<Antioxidant>
As the antioxidant, an amine-based antioxidant or a sulfur-based antioxidant may be used.

<Colorant>
Carbon black or the like may be used as the colorant.

<Flame retardant>
A metal hydroxide or the like may be used as the flame retardant.

<Other additives>
As other additives, plasticizers, fillers, lubricants, copper damage discoloration preventing agents, crosslinking aids, stabilizers, and the like may be used.

(2) Manufacturing method of silane graft resin composition A silane coupling agent is graft-polymerized to a non-halogen resin. For example, dicumyl peroxide as a peroxide and a silane coupling agent having a methacryl group are added to EVA and kneaded by heating. Thereby, the silane coupling agent which has a methacryl group is graft-polymerized to EVA in presence of a peroxide, and silane graft EVA is formed.

  Next, a silane graft resin composition is produced by mixing and kneading various additives with a non-halogen resin (silane graft EVA) obtained by graft polymerization of a silane coupling agent.

(3) Method for Manufacturing Electric Wire and Cable FIG. 1 is a cross-sectional view showing the structure of the electric wire, and FIG. 2 is a cross-sectional view showing the structure of the cable.

  As shown in FIG. 1, the electric wire 1 includes a conductor 10 and an insulating layer 11 that covers the conductor 10. As shown in FIG. 2, the cable 2 includes an electric wire 1 and a jacket layer (sheath layer) 12 that covers the electric wire 1.

  As a covering material (insulating layer 11 and jacket layer 12) for the electric wire or cable, a crosslinked product of the silane graft resin composition can be used.

  The electric wire 1 is manufactured as follows, for example. First, a copper wire is prepared as the conductor 10. And the silane graft resin composition mentioned above 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. Thereafter, the insulating layer 11 is exposed to an atmosphere of saturated water vapor at 60 ° C., for example, so that the silane graft resin composition forming the insulating layer 11 reacts with moisture to cause silane crosslinking. Similarly, the cable is formed by extruding the silane graft resin composition described above so as to cover the outer periphery of the electric wires 1 (10, 11) to form a jacket layer (sheath layer) 12 having a predetermined thickness. 2 can be formed. Although FIG. 2 shows the cable 2 having one electric wire, it may have two or more electric wires. For example, the jacket layer (sheath layer) 12 may be formed on the outer periphery of a stranded wire obtained by twisting two or more electric wires through an interposition or the like.

  Next, examples of the present invention will be described.

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

Non-halogen resin: ethylene-vinyl acetate copolymer (MFR [190 ° C., 2.16 kg load]: 6.0 (g / 10 min), vinyl acetate content: 28 (wt%), melting point: 72 ° C.)
Peroxide: Dicumyl peroxide Silane coupling agent: Vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane Antioxidant: Sulfur-based antioxidant, amine-based antioxidant Flame retardant: Metal hydroxides A and B with different surface treatment agents
Colorant: Carbon black Silanol condensation catalyst: Dioctyltin dineodecanoate

(1) Preparation of Silane Graft Resin Composition In Examples 1 to 4 and Comparative Examples 1 to 4, a silane graft resin was obtained by grafting using the above materials with the formulation shown in the column of “Silane Graft” in Table 1. Then, the silane graft resin composition was prepared by mixing with the additive in the formulation shown in the “additive kneading” column. Example 1 will be specifically described below. Each processing condition is an example.

(Grafting)
Prior to the grafting treatment, ethylene-vinyl acetate copolymer (EVA) was pretreated.

  Specifically, as shown in Table 1, 100 parts by mass of EVA was kneaded using an 8-inch roll machine. At this time, the surface temperature of the roll was set to 100 ° C. and kneaded for 5 minutes. Thereafter, the sheet obtained by kneading was pelletized into a 5 mm square shape to obtain a pellet containing EVA.

  Subsequently, grafting was performed on the obtained pellets. Specifically, the pellet obtained was impregnated with a silane mixture in which a peroxide was dissolved in a silane coupling agent in a plastic bag. At this time, as shown in Table 1, the pellet was impregnated with a silane mixture so that the peroxide was 0.1 part by mass and the silane coupling agent was 3.92 parts by mass with respect to 100 parts by mass of EVA. . The pellets impregnated with the silane mixture were 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 coupling agent to EVA. As a result, a silane graft EVA was formed. Then, the silane graft EVA was sent to the head part 104 of the single screw extruder 100, and the strand 20 (length 150 cm) of the silane graft EVA 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 a pelletizer 108 to obtain a pellet-shaped silane grafted product.

  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), the screw 102 was made into a full flight shape, and the compression ratio was 2.0. Further, a die having a hole diameter of 5 mm and three holes was used as the die 105.

(Additive kneading process)
Subsequently, the silane grafted product (silane graft EVA) and the additive were kneaded with an 8-inch roll machine to obtain a sheet-like additive kneaded product. As additives, 2.5 parts by mass of sulfur-based antioxidant, 1.5 parts by mass of amine-based antioxidant, 35 parts by mass of metal oxide A as a flame retardant, metal oxide 65 parts by mass of B and 5 parts by mass of carbon black were added. In addition, at the time of kneading, the surface temperature of the roll was set to 170 ° C., and all the additives were added and then kneaded for 5 minutes to obtain the additive kneaded sheet. The obtained sheet was pelletized into a 5 mm square shape to obtain a pellet-shaped additive kneaded material.

(Preparation of catalyst masterbatch)
Subsequently, separately from the silane grafted product (silane graft EVA), a catalyst masterbatch containing a silanol condensation catalyst was prepared.

  Specifically, as shown in the column of “Catalyst Masterbatch” in Table 1, 1 part by mass of silanol condensation catalyst was added to 99 parts by mass of EVA and kneaded using an 8-inch roll machine. At this time, the surface temperature of the roll was set to 80 ° C., and the silanol condensation catalyst was added and then kneaded for 3 minutes to obtain a sheet made of the kneaded product. Thereafter, the obtained sheet was pelletized into a 5 mm square shape to prepare a catalyst master batch.

(Preparation of silane graft resin composition)
Finally, 5 parts by mass of the catalyst master batch was added to the additive kneaded product and dry blended to prepare the silane graft resin composition of Example 1.

  The amounts of the silane coupling agent and peroxide are changed as shown in Table 1, and the silane graft resin compositions of Examples 2-3 and Comparative Examples 1-4 are prepared in the same manner as in Example 1 above. (Table 1). In Table 1, the amount of silane coupling agent is adjusted so as to be equimolar.

(2) Production of electric wires Next, electric wires were produced using the silane graft resin compositions of Examples 1 to 4 and Comparative Examples 1 to 4.

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 above-mentioned silane graft resin composition was extruded to form an insulating layer (coating material) having a thickness of 1.0 mm, thereby producing an electric wire. Thereafter, the electric wire 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 insulating layer.

  In the production of the electric wire 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. Further, the temperature of the cylinder 103a was 150 ° C., the temperature of the cylinder 103b was 180 ° C., the temperature of the neck 109 was 180 ° C., the temperature of the crosshead 110 was 180 ° C., and the temperature of the die 105 was 180 ° 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 About the silane graft resin composition and electric wire of Examples 1-4 and Comparative Examples 1-4, the external appearance and the gel fraction were evaluated with the following method. The gel fraction is an index indicating the degree of crosslinking of the material.

(appearance)
About the insulating layer (coating material) of the said electric wire, the external appearance was evaluated visually. Specifically, regarding the surface state of the insulating layer of the electric wire, “◎” indicates that the surface is sufficiently smooth, and “○” indicates that there is no level of roughness (such as roughness) as a coating material, and surface roughness The case where the occurrence of the surface roughness was indicated by “Δ”, and the case where the surface roughness was significant was indicated by “x” (see the column “Appearance of coating material” in Table 1). Among these, “◎” and “◯” were “pass”, and “△” and “×” were “exterior appearance”.

(Gel fraction before and after crosslinking)
The gel fractions before and after crosslinking of the silane graft resin compositions of Examples 1 to 4 and Comparative Examples 1 to 4 were measured. The gel fraction before crosslinking was measured for the silane grafted product and the kneaded product. The gel fraction after crosslinking was measured using the insulating layer of the electric wire.

  Specifically, the gel fraction before crosslinking was measured by the following method. First, 0.5 g of a sample was collected from the silane grafted product or the kneaded product, and the sample was placed in a 40 mesh brass wire mesh. Subsequently, the sample was extracted with xylene in a 110 ° C. oil bath for 24 hours. After the extraction treatment, the remaining sample was taken out from xylene, air dried overnight, and then vacuum dried at 80 ° C. for 4 hours. Then, the weight of the remaining sample after drying is weighed, and the gel content of the sample is calculated by the following formula (1) from the weight (preparation amount) W1 of the sample before xylene extraction and the weight W2 of the sample after xylene extraction / drying. The rate F1 was calculated.

F1 (%) = (W2 / W1) × 100 (1)
The gel fraction after crosslinking was obtained by taking 0.5 g of a sample from the insulating layer of the wire, extracting and drying xylene in the same manner as described above, and the weight (preparation amount) W1 of the sample before xylene extraction and xylene extraction / drying. From the mass W2 of the later sample, the gel fraction F2 of the sample was calculated by the following formula (2).

F2 (%) = (W2−W1 × (z / x)) / (W1 × (y / x)) × 100 (2)
In formula (2), x is the total blending amount (parts by weight), y is the base polymer blending amount (parts by weight), and z is the metal hydroxide blending amount (parts by weight). Thus, in the gel fraction after cross-linking defined by the formula (2), the metal hydroxide (100 parts by weight) was calculated as a polymer gel not included in the xylene insoluble content.

  In this example, a case where the gel fraction after cross-linking is 50% or more is regarded as acceptable “◯”, and a case where the gel fraction is less than 50% is regarded as defective “x”. The gel fraction of the silane grafted product and the gel fraction of the kneaded product are shown as reference values in the “after silane grafting” column and “after additive kneading” column of Table 1, respectively.

(4) Determination The determination (overall evaluation) is shown in the bottom column of Table 1. In both the appearance and the gel fraction after cross-linking, those that passed were judged as good (◯), and those that were poor were judged as bad (x). In Examples 1 to 4, the determination was good (◯), and in Comparative Examples 1 to 4, the determination was impossible (x).

  In Example 1, 100 parts by weight of EVA, 3.92 parts by weight of 3-methacryloxypropyltriethoxysilane as a silane coupling agent, and 0.1 parts by weight of dicumyl peroxide as a peroxide were mixed and grafted. Went. The gel fraction of the silane grafted product was 2%, and no particular problem was found in the silane grafting work. Moreover, compared with the time of using the silane coupling agent (for example, vinyl trimethoxysilane) which has a vinyl group, there was little irritating odor by a silane coupling agent, and the problem was not seen by work environment property. Further, the gel fraction (polymer gel) of the additive kneaded product was 15%, and no particular abnormality was observed in the appearance of the sheet-like additive kneaded product. A pellet (silane graft resin composition) obtained by dry blending a catalyst masterbatch with the additive kneaded product was put into an extruder to produce an electric wire. The electric wire had a sufficiently smooth appearance, and saturated steam at 60 ° C. for 24 hours. The gel fraction (polymer gel) after the crosslinking treatment was 56%, which was a sufficient degree of crosslinking.

  In Example 2, 100 parts by weight of EVA was mixed with 3.35 parts by weight of 3-methacryloxypropyltrimethoxysilane as a silane coupling agent and 0.1 part by weight of dicumyl peroxide as a peroxide for grafting. Went. The gel fraction of the silane grafted product was 3%, and no particular problem was found in the silane grafting work. Moreover, compared with the time of using the silane coupling agent (for example, vinyl trimethoxysilane) which has a vinyl group, there was little irritating odor by a silane coupling agent, and the problem was not seen by work environment property. Further, the gel fraction (polymer gel) of the additive kneaded product was 17%, and no particular abnormality was observed in the appearance of the sheet-like additive kneaded product. A pellet (silane graft resin composition) obtained by dry blending a catalyst masterbatch with the additive kneaded product was put into an extruder to produce an electric wire. The electric wire had a sufficiently smooth appearance, and saturated steam at 60 ° C. for 24 hours. The gel fraction (polymer gel) after the crosslinking treatment was 57%, which was a sufficient degree of crosslinking.

  In Example 3, 100 parts by weight of EVA was mixed with 3.35 parts by weight of 3-methacryloxypropyltrimethoxysilane as a silane coupling agent, and 1.0 part by weight of dicumyl peroxide as a peroxide for grafting. Went. The gel fraction of the silane grafted product was 8%, and no particular problem was found in the silane grafting work. Moreover, compared with the time of using the silane coupling agent (for example, vinyl trimethoxysilane) which has a vinyl group, there was little irritating odor by a silane coupling agent, and the problem was not seen by work environment property. Moreover, the gel fraction (polymer gel) of the additive kneaded product was 22%, and no particular abnormality was observed in the appearance of the sheet-like additive kneaded product. A pellet (silane graft resin composition) obtained by dry blending a catalyst masterbatch with the additive kneaded product was put into an extruder to produce an electric wire. The electric wire had a sufficiently smooth appearance, and saturated steam at 60 ° C. for 24 hours. The gel fraction (polymer gel) after the crosslinking treatment was 69%, which was a sufficient degree of crosslinking.

  In Example 4, 100 parts by weight of EVA was mixed with 3.35 parts by weight of 3-methacryloxypropyltrimethoxysilane as a silane coupling agent and 1.25 parts by weight of dicumyl peroxide as a peroxide for grafting. Went. The gel fraction of the silane grafted product was 15%, and some discharge unevenness was observed, but no problem was found in workability. Moreover, compared with the time of using the silane coupling agent (for example, vinyl trimethoxysilane) which has a vinyl group, there is little irritating odor by a silane coupling agent, and the problem was not seen especially in the silane grafting operation. Further, the gel fraction (polymer gel) of the additive kneaded product was 28%, and no particular abnormality was observed in the appearance of the sheet-like additive kneaded product. A pellet (silane graft resin composition) obtained by dry blending a catalyst masterbatch with the additive kneaded product was put into an extruder to produce an electric wire. As a result, a slight roughness was observed in the appearance of the electric wire. Was a satisfactory level, and the gel fraction (polymer gel) after crosslinking treatment in saturated water vapor at 60 ° C. for 24 hours was a sufficient crosslinking degree of 72%.

  In Comparative Example 1, grafting was performed by mixing 100 parts by weight of EVA with 2 parts by weight of vinyltrimethoxysilane as a silane coupling agent and 0.05 parts by weight of dicumyl peroxide as a peroxide. The gel fraction of the silane grafted product was 0%, but there is an irritating odor due to vinyltrimethoxysilane volatilized during the silane grafting work, and measures to improve the working environment are required. Moreover, the gel fraction (polymer gel) of the additive kneaded product was 42%, and a remarkable roughness was observed in the appearance of the sheet-like additive kneaded product. When the pellets (silane graft resin composition) obtained by dry blending the catalyst masterbatch with the additive kneaded product were put into an extruder to produce an electric wire, the appearance of the electric wire was noticeably rough and the appearance was poor as a coating material. It was judged that. The gel fraction (polymer gel) after crosslinking in saturated steam at 60 ° C. for 24 hours was 67%, which was a sufficient degree of crosslinking.

  In Comparative Example 2, grafting was performed by mixing 100 parts by weight of EVA with 2 parts by weight of vinyltrimethoxysilane as a silane coupling agent and 0.1 parts by weight of dicumyl peroxide as a peroxide. The gel fraction of the silane grafted product was 22%, but there is an irritating odor due to vinyltrimethoxysilane volatilized during the silane grafting work, and measures to improve the working environment are required. Moreover, the gel fraction (polymer gel) of the additive kneaded product was 54%, and a remarkable roughness was observed in the appearance of the sheet-like additive kneaded product. When the pellets (silane graft resin composition) obtained by dry blending the catalyst masterbatch with the additive kneaded product were put into an extruder to produce an electric wire, the appearance of the electric wire was noticeably rough and the appearance was poor as a coating material. It was judged that. Further, the gel fraction (polymer gel) after crosslinking treatment in saturated steam at 60 ° C. for 24 hours was 72% and a sufficient degree of crosslinking.

  In Comparative Example 3, grafting treatment was performed by mixing 100 parts by weight of EVA with 3.35 parts by weight of 3-methacryloxypropyltrimethoxysilane as a silane coupling agent and 0.05 parts by weight of dicumyl peroxide as a peroxide. Went. The gel fraction of the silane grafted product was 0%, and no particular problem was found in the silane grafting work. Moreover, compared with the time of using the silane coupling agent (for example, vinyl trimethoxysilane) which has a vinyl group, there was little irritating odor by a silane coupling agent, and the problem was not seen by work environment property. Moreover, the gel fraction (polymer gel) of the additive kneaded product was 16%, and no particular abnormality was observed in the appearance of the sheet-like additive kneaded product. A pellet (silane graft resin composition) obtained by dry blending a catalyst masterbatch with the additive kneaded product was put into an extruder to produce an electric wire. The electric wire had a sufficiently smooth appearance, and saturated steam at 60 ° C. for 24 hours. The gel fraction (polymer gel) after crosslinking treatment was 43%, showing a decrease in the degree of crosslinking.

  In Comparative Example 4, 100 parts by weight of EVA was mixed with 3.35 parts by weight of 3-methacryloxypropyltrimethoxysilane as a silane coupling agent and 1.5 parts by weight of dicumyl peroxide as a peroxide for grafting. Went. Since the gel fraction of the silane grafted product is 23% and discharge unevenness was observed, it can be said that there are some problems in workability. However, compared with the use of a silane coupling agent having a vinyl group (for example, vinyltrimethoxysilane), there was less irritating odor due to the silane coupling agent, and no problem was found in the work environment. Moreover, the gel fraction (polymer gel) of the additive kneaded product was 36%, and the appearance of the sheet-like additive kneaded product was rough. When the pellets (silane graft resin composition) obtained by dry blending the catalyst masterbatch with the additive kneaded product were put into an extruder to produce an electric wire, the appearance of the electric wire was rough and the appearance was poor as a coating material. Judged that there was. Further, the gel fraction (polymer gel) after crosslinking treatment in saturated steam at 60 ° C. for 24 hours was 79% and a sufficient degree of crosslinking.

  From the comparative examples 1 and 2 and Examples 1 to 4, the use of a silane coupling agent having a methacrylic group as a silane coupling agent results in poor appearance of the wire coating material. It turns out that it reduces.

  As in Comparative Examples 1 and 2, when an electric wire coating material is constituted by a silane grafted product using vinyltrimethoxysilane, the appearance is poor. Moreover, in the said comparative examples 1 and 2, the gel fraction of a kneaded processed material is rising significantly with respect to the gel fraction of a silane graft processed material.

  From the above events, the appearance defects are affected by the compatibility of the silane coupling agent and the resin during << 1 >> grafting, and the progress of an undesired crosslinking reaction during kneading of << 2 >> additives. it seems to do.

  Regarding << 1 >> above, a silane coupling agent containing a vinyl group (for example, vinyltrimethoxysilane) is more compatible with a non-halogen resin (for example, EVA) than a silane coupling agent having a methacryl group. Since it is low, the graft portion of the silane coupling agent is likely to be localized. When the additive is mixed, an undesired crosslinking reaction due to condensation of silanes proceeds in the localized graft portion.

  As described above, the silane coupling agent has a functional group (unsaturated bond group) that bonds to the resin (polymer) in addition to the hydrolyzable group such as an alkoxy group. The solubility parameter varies depending on the type of functional group. This solubility parameter is a numerical value calculated from the molecular structure, and it is empirically known that the closer the numerical value between different materials, the higher the compatibility. When the difference in solubility parameter is generally within 1.0, relatively good compatibility is often exhibited.

  For example, although it depends on the vinyl acetate content, the solubility parameter of EVA is about 9.0 to 9.5. On the other hand, the solubility parameter of the silane coupling agent having a vinyl group (vinyl silane) is 7.5, and the compatibility with EVA is low. On the other hand, the solubility parameter of the silane coupling agent (methacrylic silane) containing a methacryl group as a functional group is 8.7, and the compatibility with EVA is high.

  Therefore, when EVA is grafted using methacrylic silane, these silane coupling agents are relatively homogeneously bonded (grafted) to EVA molecules because of their high compatibility. For this reason, it becomes possible to suppress the crosslinking reaction when the additive (particularly, the metal hydroxide of the flame retardant) is mixed with the above << 2 >>.

  In particular, non-halogen resins such as EVA tend to have low flame retardancy of the resin itself, and a relatively large amount of flame retardant is often added when applied to a coating material for electric wires and cables. The amount of the flame retardant added is, for example, about 50 to 250 parts by weight. Thus, even when a flame retardant is added, it becomes possible to suppress a crosslinking reaction during mixing of the flame retardant.

  Further, from Comparative Examples 3 and 4 and Examples 1 to 4, even when methacrylic silane was used as the silane coupling agent, if the addition ratio of the peroxide at the time of grafting was too small, The gel fraction is slightly small and the degree of crosslinking is slightly decreased (Comparative Example 3). On the other hand, if the ratio of the peroxide added is too large, the crosslinking reaction easily proceeds during the grafting process, and the surface of the coating material is rough (Comparative Example 4). However, it is not a remarkable roughness like Comparative Examples 1 and 2.

  In the said Examples 1-4, the compounding ratio (Rc) of a silane coupling agent and a peroxide is 18.2, 18.2, 1.8, and 1.5, respectively (Table 1). Thus, it is preferable to adjust the blending ratio (Rc) to be in an appropriate range (for example, 1.5 to 20). By such adjustment, the amount of radicals generated by the decomposition of the peroxide can be secured, and the unintended crosslinking reaction during the grafting process can be suppressed while the grafting reaction is sufficiently advanced.

  In the above embodiment, dicumyl peroxide was used as the peroxide, but it is not limited to this. Dicumyl peroxide has a high hydrogen abstraction ability and a 1-minute half-life temperature of about 175 ° C., which is preferable as a peroxide. In addition, it is preferable to use a peroxide having a relatively high hydrogen abstraction ability and a one-minute half-life temperature of 120 ° C. to 200 ° C. In view of the graft reaction time during production, it is more preferable to use a peroxide having a 1 minute half-life temperature of 150 ° C. to 200 ° C. Specifically, 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-ethylhexyl carbonate, etc. Can do. These peroxides may be used alone or in combination of two or more.

  In the above examples, 3-methacryloxypropyltriethoxysilane and 3-methacryloxypropyltrimethoxysilane were used as methacrylic silane, but 3-methacryloxypropylmethyldimethoxysilane and 3-methacryloxypropylmethyl were also used. Diethoxysilane or the like can be used. These silane compounds may be used alone or in combination of two or more as the silane coupling agent.

  Moreover, as long as the said methacryl silane is included, you may mix and use other silane compounds, such as vinyl silane, in a silane coupling agent.

  In the above examples, EVA was used as the non-halogen resin. However, other polyolefin resins such as ethylene ethyl acrylate copolymer (EEA), ethylene methyl acrylate copolymer (EMA), α-olefin copolymer, Polyethylene, polypropylene, ethylene propylene copolymer, ethylene propylene diene copolymer, modified products thereof, a mixture thereof, and the like may be used.

  In the above examples, metal hydroxide was used as the flame retardant. For example, phosphoric acid ester, (poly) ammonium phosphate, red phosphorus, etc. Sand, zinc borate, sodium polyborate, and other nitrogen-containing flame retardants, melamine cyanurate, guanidine compounds, triazine compounds, ammonium phosphate, ammonium carbonate, etc. Silicone flame retardants, silicone resins, and other flame retardants Alternatively, zinc stannate, molybdenum compound, or the like may be used.

  The structure and size of the electric wires produced in the above examples are examples, and are not limited to those described above. Moreover, in the said Example, although the silane graft EVA was used as a coating material of an electric wire, you may use a silane graft EVA as a coating material of a cable.

  Moreover, in the said Example, although the roll machine and the extruder were used in the grafting process and the kneading | mixing process, you may use a kneader, a mixer, an autoclave, etc. in addition to this. Moreover, the processing conditions (temperature, time, etc.) of the grafting and kneading processes are merely examples, and are not limited to these conditions.

  In the above examples, the crosslinking treatment was performed by storing in a constant temperature and humidity chamber having a temperature of 60 ° C. and a relative humidity of 95% for 24 hours. As the crosslinking treatment, at least water and a covering material such as an electric wire It is sufficient that the crosslinking reaction proceeds by the action, and specific crosslinking conditions can be appropriately changed. For example, in addition to the constant temperature and humidity chamber, conditions such as the processing location, humidity, temperature, and time can be changed as appropriate, such as using a steam chamber or simply leaving the building indoors or outdoors.

  As described above, the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the scope of the invention.

[Appendix 1]
(A) a step of forming a silane graft resin by grafting a silane compound to a non-halogen resin;
(B) adding an additive to the silane graft resin and kneading to form an additive kneaded product,
Have
The silane compound has an unsaturated bond group and a hydrolyzable silane group,
The unsaturated bond group is a methacryl group,
The manufacturing method of the silane graft | grafting resin composition whose compounding ratio (Rc) of the silane coupling agent and peroxide shown by the following formulas is the range of 1.5-20.
Rc = (WS / MS) / (2αWO / MO)
Where WS is the amount of silane coupling agent (g), WO is the amount of peroxide (g), MS is the molecular weight of the silane coupling agent, MO is the molecular weight of the peroxide, and α is the peroxide. The number of oxygen-oxygen bonds per molecule.

[Appendix 2]
In the method for producing a silane-grafted resin composition according to appendix 1,
(C) The process of adding a silanol condensation catalyst to the said additive kneaded material, The manufacturing method of the silane graft resin composition.

[Appendix 3]
A method for producing an electric wire or a cable, comprising: coating the silane graft resin composition of Appendix 1 or 2 on an outer periphery of a conducting wire or an electric wire, and performing a crosslinking treatment by the action of the silane graft resin composition and water.

DESCRIPTION OF SYMBOLS 1 Electric wire 2 Cable 10 Conductor 11 Insulating layer 12 Outer layer 100 Single screw extruder 101 Hopper 102 Screw 103a Cylinder 103b Cylinder 104 Head part 105 Die 106 Water tank 107 Air wiper 108 Pelletizer 109 Neck 110 Cross head part

Claims (7)

A silane graft resin composition comprising a non-halogen resin, a silane graft resin obtained by grafting a silane compound using a peroxide, and an additive,
The silane compound has an unsaturated bond group and a hydrolyzable silane group,
The unsaturated bond group is a methacryl group,
The silane graft resin composition whose compounding ratio (Rc) of the silane coupling agent and peroxide shown by the following formula | equation is the range of 1.5-20.
Rc = (WS / MS) / (2αWO / MO)
Where WS is the amount of silane coupling agent (g), WO is the amount of peroxide (g), MS is the molecular weight of the silane coupling agent, MO is the molecular weight of the peroxide, and α is the peroxide. The number of oxygen-oxygen bonds per molecule. In the silane graft resin composition according to claim 1,
A silane graft resin composition having a gel fraction after crosslinking of 50% or more. In the silane graft resin composition according to claim 1,
The non-halogen resin is a silane graft resin composition containing an ethylene-vinyl acetate copolymer. In the silane graft resin composition according to claim 3,
The silane compound is a silane graft resin composition, wherein the silane compound is 3-methacryloxypropyltrimethoxysilane or 3-methacryloxypropyltriethoxysilane. In the silane graft resin composition according to claim 4,
The additive is a silane graft resin composition, which is a flame retardant.   An electric wire provided with the insulating layer formed from the crosslinked material of the silane graft composition in any one of Claims 1-5.   A cable comprising a jacket layer formed from a crosslinked product of the silane graft composition according to claim 1.

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