JP7424253B2 - Cables and insulated wires - Google Patents

Description

The present invention relates to cables and insulated wires.

A cable is constructed by, for example, providing an outer skin layer (a so-called sheath) as a covering material around an insulated wire having an insulating layer provided around a conductor. The outer skin layer is formed from a resin composition whose main raw materials are rubber or resin, and as this resin composition, for example, a soft vinyl chloride resin composition (soft PVC) containing a flame retardant is used.

Different properties are required of the resin composition depending on the use of the cable. For example, cables for factory automation robots are required to be flame retardant, heat resistant, and resilient. In particular, in recent years, FA robots have been constructed with multiple joints and multiple axes, and the cables used are repeatedly bent as the equipment moves, so high resilience is required. Resilience refers to the ability of a cable to return to its original shape when bent.

However, when soft PVC is used for the outer skin layer, the resilience of the outer skin layer is low, so the cable may break during operation of the FA robot. Therefore, for cables that require resilience, it has been proposed to use a resin composition in which soft PVC is blended with an ether-based urethane thermoplastic elastomer (hereinafter simply referred to as TPU) (see, for example, Patent Document 1). ).

Japanese Patent Application Publication No. 2016-91975

The present inventor has studied the application of a resin composition in which polyvinyl chloride resin (PVC) is blended with thermoplastic urethane elastomer (TPU) as the outer skin layer of the cable, and is aiming to improve the resilience. Another performance required of the resin composition for the outer skin layer is crosslinkability. In the resin composition for the outer skin layer, crosslinking is performed to suppress deformation and breakage due to heat load and external pressure, and to improve heat resistance. For such crosslinking, there is a crosslinking method using electron beams, but for example, the electrical properties of TPU may deteriorate when irradiated with electron beams, and sufficient crosslinking properties cannot be obtained unless the irradiation intensity is high. There is. On the other hand, when PVC is irradiated with electron beams at high irradiation intensity, there is a problem that the heat resistance and cold resistance decrease.

An object of the present invention is to provide a technique for obtaining a high level of resilience, crosslinkability, electrical properties, heat resistance, and cold resistance in a well-balanced manner in an insulator such as an outer skin layer of a cable.

[1] The cable of the present invention is a cable comprising an insulated wire and an outer skin layer coated around the insulated wire, wherein the insulated wire includes a conductor and an insulating layer coated around the conductor. and the outer skin layer is formed from a resin composition containing a base polymer (A), a plasticizer (B), a stabilizer (C), a flame retardant (D) and other additives (E), The base polymer (A) contains a polyvinyl chloride resin (a1) and at least one urethane thermoplastic elastomer (a2) of adipate, lactone and carbonate types, and the stabilizer (C) is hydrotalcite. (c1) and a metal soap (c2), the flame retardant (D) is a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silica (d3) and antimony trioxide (d4). The other additive (E) includes fired clay, and the fired clay contains 35 parts by mass or more based on 100 parts by mass of the polyvinyl chloride resin (a1).

[2] In [1], the other additive (E) includes a crosslinking aid, and the crosslinking aid is contained in an amount of 3 parts by mass or more based on 100 parts by mass of the polyvinyl chloride resin (a1). ing.

[3] In [2], the crosslinking aid is either trimethylolpropane trimethacrylate, triallyl isocyanurate, or triallyl cyanurate .

[4] In any one of [1] to [3], the base polymer (A) contains chlorinated polyethylene.

[5] In any one of [1] to [4], the outer skin layer is crosslinked with an electron beam having an irradiation intensity of 0.5 Mrad or more and 8 Mrad or less.

[6] In any of [1] to [5], the gel fraction derived from the urethane thermoplastic elastomer (a2) is not expressed in the outer skin layer.

[7] The insulated wire of the present invention is an insulated wire comprising a conductor and an insulating layer coated around the conductor, the insulating layer comprising a base polymer (A), a plasticizer (B), a stabilizer The base polymer (A) is composed of a polyvinyl chloride resin (a1) and an adipate-based, lactone-based and at least one carbonate-based urethane thermoplastic elastomer (a2), the stabilizer (C) contains hydrotalcite (c1) and a metal soap (c2), and the flame retardant (D) contains a metal water oxide (d1), brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4), and the other additive (E) includes calcined clay; The fired clay contains 35 parts by mass or more based on 100 parts by mass of the polyvinyl chloride resin (a1).

According to the present invention, high levels of restorability, crosslinkability, electrical properties, heat resistance, and cold resistance can be obtained in a well-balanced manner in an insulator such as a cable outer skin layer.

It is a sectional view of the cable of an embodiment. FIG. 2 is a diagram schematically showing the phase structure of a resin composition used for the outer skin layer of the cable according to the embodiment.

(Considerations)
First, before describing the embodiments, matters considered by the inventor will be described.

As mentioned above, the present inventor applied a resin composition containing polyvinyl chloride resin (PVC) and thermoplastic urethane elastomer (TPU) as the outer skin layer of the cable, thereby improving the resilience of the outer skin layer of the cable. We are considering this.

In the process of such studies, there were some that showed a decrease in crosslinking properties (see Comparative Examples and Reference Examples described later). Thus, the resin composition for the outer skin layer is required to have crosslinking properties. Crosslinking can suppress deformation and damage due to thermal load and external pressure, and improve heat resistance. There is a crosslinking method using electron beams for such crosslinking, but TPU cannot be crosslinked unless it is exposed to high-intensity electron beams, whereas PVC polymer disintegration progresses due to high-intensity electron beams. There is a risk that Further, TPU also undergoes crosslinking and disintegration at the same time due to high irradiation intensity electron beams. In this way, in a resin composition containing PVC and TPU, if the electron beam irradiation intensity is too low, crosslinking will be insufficient, resulting in a decrease in electrical properties, and if it is too high, the polymer will collapse, resulting in poor heat resistance. There is a problem that cold resistance decreases.

Therefore, the present inventor created a resin composition in which non-crosslinked TPU was dispersed as domains in a crosslinked PVC matrix as shown in FIG. It was discovered that it is possible to maintain crosslinking properties while suppressing the irradiation intensity of electron beams, thereby suppressing the collapse of TPU and PVC polymers (improving electrical properties, heat resistance, and cold resistance).

Specifically, we have discovered the composition of a resin composition and electron beam irradiation conditions that can provide a good balance of restorability, crosslinkability, electrical properties, heat resistance, and cold resistance at a high level.

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

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment)
EMBODIMENT OF THE INVENTION Hereinafter, the cable based on Embodiment 1 embodiment of this invention is demonstrated using figures. FIG. 1 is a sectional view perpendicular to the length direction of a cable according to an embodiment of the present invention. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as the lower limit and upper limit.

(Cable configuration)
FIG. 1 is a cross-sectional view of the cable according to the first embodiment. FIG. 1 shows a section perpendicular to the length of the cable. The cable of this embodiment is flame retardant and has high resilience, which is applied to cables for factory automation robots, for example.

As shown in FIG. 1, the cable 1 of this embodiment includes an insulated wire 10 in which an insulating layer 12 is formed around a conductor 11, a shield layer 13 provided around the insulated wire 10, and a shield layer 13 provided around the shield layer 13. and an outer skin layer 14 formed on the outer skin layer 14.

(insulated wire)
As the conductor 11, commonly used metal wires such as copper wires and copper alloy wires, as well as aluminum wires, gold wires, silver wires, etc. can be used. Further, as the conductor 11, a metal wire plated with a metal such as tin or nickel may be used. Furthermore, as the conductor 11, a twisted wire made by twisting metal wires together can also be used.

Insulating layer 12 is provided around conductor 11 . There are no restrictions on the material of the insulating layer 12, and for example, ETFE (tetrafluoroethylene/ethylene copolymer), which is a fluororesin, can be used. Further, a resin composition for the outer skin layer of the cable of this embodiment described later may be used. The thickness of the insulating layer 12 is not particularly limited, and may be, for example, 0.1 mm to 1.5 mm. After coating with the insulating layer, crosslinking is performed with an electron beam using an electron beam irradiation device.

(shield layer)
The shield layer 13 is provided, for example, around a core portion formed by twisting five two-strand insulated wires 10 together. Note that the number of insulated wires 10 provided in the core portion is not limited, and may be one. The shield layer 13 is formed by, for example, a braided structure in which a plurality of metal wires such as annealed copper wires are woven together.

(outer skin layer)
The outer skin layer (sheath, sheath layer) 14 is provided around the shield layer 13 and is made of a resin composition described below. Although the thickness of the outer skin layer 14 is not particularly limited, it is preferably 0.1 mm to 1.4 mm from the viewpoint of obtaining a high level of various properties in a well-balanced manner.

(Resin composition)
Next, the resin composition for the outer skin layer of the cable of this embodiment will be explained. Since this resin composition has flame retardancy and is further crosslinked as described below, it can also be referred to as a "flame retardant resin composition" or a "flame retardant crosslinked resin composition."

The resin composition constituting the outer skin layer includes a base polymer (A), a plasticizer (B), a stabilizer (C), a flame retardant (D), and other additives (E).

(Base polymer (A))
In this embodiment, base polymers include polyvinyl chloride resin (PVC, a1), at least one urethane thermoplastic elastomer (TPU, a2) of adipate type, lactone type, and carbonate type, and chlorinated polyethylene (CPE, a3). ).

Polyvinyl chloride resin (PVC, a1) not only contributes to flame retardancy, but also allows flexibility, cold resistance, etc. to be adjusted freely by using a plasticizer. PVC is obtained by polymerizing a vinyl chloride monomer obtained by an oxychlorination method using an aqueous suspension method.

As PVC, in addition to homopolymers of vinyl chloride, copolymers of vinyl chloride and other copolymerizable monomers, etc. can be used. As such a copolymer, for example, a copolymer of vinyl chloride and ethylene or a copolymer of vinyl acetate or the like can be used. Further, as the PVC, one that has been crosslinked is used.

The average degree of polymerization of PVC is not particularly limited, but is preferably from 1,000 to 3,800, more preferably from 1,300 to 2,500. By setting the average degree of polymerization to 1000 or more, high heat resistance can be obtained in the insulating layer. On the other hand, if the average degree of polymerization becomes too high, there is a risk that the moldability of the resin composition will decrease, but by setting the average degree of polymerization to 3800 or less, the heat resistance of the outer skin layer can be improved without impairing the moldability. can be made higher. Note that, as PVC, a plurality of PVCs having different average degrees of polymerization may be used in combination.

The thermoplastic urethane elastomer (TPU, a2) is a component that primarily provides resilience to the insulating layer. TPU is adipate-based, lactone-based, or carbonate-based. Adipate type TPU is obtained by reaction with adipic acid type polyester polyol, diol, and isocyanate. The lactone-based TPU is obtained by reacting, for example, a caprolactane-based polyester polyol with a diol and an isocyanate. The carbonate type is, for example, TPU obtained by reacting a carbonate compound type polyester polyol with a diol or an isocyanate.

Examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, and 1,8-octanediol. , 1,9-nonanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3 , 3,5-trimethylpentanediol, 2,4-diethyl-1,5-pentanediol, 1,12-octadecanediol, 1,2-alkanediol, 1,3-alkanediol, 1-monoglyceride, 2-monoglyceride , 1-monoglycerin ether, 2-monoglycerin ether, dimer diol, hydrogenated dimer diol, and the like.

Examples of the isocyanate include hexamethylene diisocyanate, butane-1,4-diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, xylylene diisocyanate, m-tetramethylxylylene diisocyanate. Examples include aliphatic diisocyanates such as. Also, isophorone diisocyanate, cyclohexane-1,4-diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, Examples include alicyclic diisocyanates such as isopropylidene dicyclohexyl-4,4'-diisocyanate and norbornane diisocyanate. Furthermore, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1 , 3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, and tetramethylxylylene diisocyanate.

The TPU is not particularly limited as long as it is adipate-based, lactone-based, or carbonate-based from the viewpoint of heat resistance of the insulating layer, but adipate-based is preferable from the viewpoint of adjusting the hardness in the outer skin layer. In addition to adjusting hardness, adipate-based resins have excellent affinity with polyvinyl chloride resins compared to lactone-based and carbonate-based resins, and are easy to form the phase structure described below in the resin composition that constitutes the outer skin layer, and have various properties. can be achieved more stably and at a higher level. This is because adipate-based TPU has a structure derived from adipic acid, so even if additives are added, the bonding strength due to the hydrogen bonds and urethane bonds of the hard segments is not significantly impaired, and various properties are easily maintained at high levels.

The hardness of the adipate TPU is not particularly limited, but from the viewpoint of the balance between the resilience and heat resistance of the outer skin layer, it is preferably 80A to 95A in terms of Shore A hardness, and more preferably 80A to 90A. preferable.

The amount of chlorine contained in chlorinated polyethylene (CPE, A3) is not particularly limited, but from the viewpoint of increasing cold resistance and flame retardancy, it is preferably 20% or more, and preferably 20% to 45%. More preferred. Note that a plurality of CPEs having different amounts of chlorine may be used together.

Note that the base polymer (A) must include at least the above-mentioned polyvinyl chloride resin (PVC, a1) and thermoplastic urethane elastomer (TPU, a2), and chlorinated polyethylene (CPE, a3) must be omitted. (See examples below). In other words, in addition to the polyvinyl chloride resin (PVC, a1) and the thermoplastic urethane elastomer (TPU, a2), the base polymer (A) contains other polymer components that have the properties of the insulating layer. In addition to chlorinated polyethylene, other polymer components include ethylene-vinyl acetate copolymer, styrene elastomer, ethylene-α-olefin copolymer, ethylene-acrylic acid, etc. Ester copolymers, acrylic resins, modified products thereof, etc. can be used. Among these, it is preferable to use chlorinated polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester copolymer from the viewpoint of having excellent affinity with TPU and obtaining various properties at a higher level. , it is preferable to use chlorinated polyethylene.

(Plasticizer (B))
The plasticizer (B) is a component that imparts flexibility to the outer skin layer. As the plasticizer (B), trimellitic acid ester, phthalic acid ester, adipic acid polyester, etc. can be used. Among these, trimellitic acid ester is preferable because it does not impair various properties of the outer skin layer. Trimellitic acid ester can maintain higher heat resistance of the outer skin layer than phthalic acid ester. Furthermore, since it does not cause stickiness in the outer skin layer compared to adipic acid polyester, it is possible to improve the handling properties of the cable. Although trimellitic acid ester may be used alone, it may also be used in combination with, for example, adipic acid polyester, etc., to the extent that the properties of the outer skin layer are not impaired.

As the trimellitic acid ester, for example, di-2-ethylhexyl trimellitate, tri-2-ethylhexyl trimellitate, tri-n-octyl trimellitate, mixed alkyl trimellitate, triisononyl trimellitate, etc. can be used.

(Stabilizer (C))
The stabilizer (C) acts as a heat stabilizer that suppresses deterioration of PVC when preparing a resin composition. In this embodiment, hydrotalcite (c1) and metal soap (c2) are used from the viewpoint of selectively dispersing them in PVC. Hydrotalcite and metal soap are not particularly limited as long as they have excellent compatibility with PVC, and known components can be used. As the metal soap, for example, a component consisting of a fatty acid such as stearic acid, lauric acid, or octylic acid, and a metal such as calcium, zinc, or magnesium can be used.

In addition, hydrotalcite and metal soap can suppress the deterioration of PVC and CPE even when they are used together, and can be selectively dispersed in both, so they are suitable for use as the stabilizer (C).

The stabilizer (C) may also contain epoxidized soybean oil (c3) as a component other than the above. Epoxidized soybean oil is preferable as the stabilizer (C) from the viewpoint of imparting thermal stability to PVC and CPE.

Further, the stabilizer (C) may contain a stabilizing aid as a component other than the above. The stabilizing aid is a component that has no effect on TPU whether it is added or not, and acts only on PVC. As stabilizing aids, for example, dibensoylmethane, stearylbenzoylmethane, metal salts thereof, polyhydric alcohols, trihydroxyethyl isocyanate, silica, calcium carbonate, antioxidants, talc, clay, etc. may be used as necessary. It can be used in appropriate amounts.

(Flame retardant (D))
The flame retardant (D) is a component that imparts flame retardancy to the outer skin layer. From the viewpoint of dispersing the flame retardant in polyvinyl chloride resin, metal hydroxide (d1), brominated flame retardant (d2), amorphous silica (d3) and antimony trioxide (d4) are used as the flame retardant (D). Use at least one of the following.

As the metal hydroxide, for example, aluminum hydroxide, magnesium hydroxide, etc. can be used. Among these, aluminum hydroxide is particularly preferred. When magnesium hydroxide is used, the alkalinity in the resin composition increases, which weakens the urethane bond strength, hydrogen bond strength, ester bond strength, etc. in the hard segment of TPU, and there is a risk that the heat resistance of TPU may decrease. There is. In this regard, aluminum hydroxide allows high heat resistance to be maintained without excessively increasing alkalinity. Note that the metal hydroxide may not be surface-treated, or may be surface-treated such as silane treatment. Organic fatty acid treated products are not preferred because they degrade the performance of TPU as described above. From the viewpoint of dispersibility, the metal hydroxide preferably has an average particle size of 5 μm or less. Although the lower limit is not particularly limited, it is, for example, 0.2 μm.

As the brominated flame retardant, for example, decabromodiphenylethane or the like can be used. From the viewpoint of dispersibility, the brominated flame retardant preferably has an average particle size of 10 μm or less. Although the lower limit is not particularly limited, it is, for example, 2 μm.

From the viewpoint of dispersibility, the amorphous silica preferably has an average particle size of 5 μm or less. Although the lower limit is not particularly limited, it is, for example, 0.01 μm.

From the viewpoint of dispersibility, the antimony trioxide preferably has an average particle size of 5 μm or less. Although the lower limit is not particularly limited, it is, for example, 0.5 μm.

(Other additives (E))
In addition to components (A) to (D), other additives (E) are added to the resin composition.

In particular, in this embodiment, the other additives (E) include calcined clay (e2) and crosslinking aid (e1).

The fired clay has the function of adsorbing ionic substances in the resin composition and improving the electrical properties. As the fired clay, one that has been surface-treated may be used. The surface treatment can be performed using, for example, an organic silane compound or a silane oligomer.

Regarding the content (addition amount) of fired clay, the electrical properties can be improved by containing 35 parts by mass or more with respect to 100 parts by mass of PVC. There is no particular upper limit to the content, but it is preferably 60 parts by mass or less. By containing 60 parts by mass or less, it is possible to suppress the resin composition from becoming highly adhesive during molding and improve molding efficiency.

Examples of crosslinking aids include trimethylolpropane trimethacrylate (TMPT), triallyl isocyanurate, triallyl cyanurate, N,N'-metaphenylene bismaleimide, ethylene glycol dimethacrylate, zinc acrylate or zinc methacrylate. It will be done. The content of the crosslinking aid for obtaining the performance of the resin composition is 3 parts by mass or more based on 100 parts by mass of PVC, so that the necessary degree of crosslinking is achieved. If the amount is less than 3 parts by mass, it is necessary to increase the intensity of electron beam irradiation in order to obtain the required degree of crosslinking, resulting in a decrease in performance (electrical properties, etc.) due to deterioration of PVC and decomposition of TPU. The upper limit of the content is preferably 15 parts by mass or less from the viewpoint of imparting flame retardance.

Examples of the crosslinking aid include trimethylolpropane trimethacrylate (TMPT), triallyl isocyanurate, triallyl cyanurate, and the like from the viewpoint of cost.

As other additives (E), colorants, antioxidants (heat antiaging agents), copper damage inhibitors, lubricants, processing aids, etc. may be used.

Examples of the colorant include colorant black and colorant white.

Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, and sulfur antioxidants.

Examples of copper damage inhibitors include N-(2H-1,2,4-triazol-5-yl)salicylamide, dodecanedioic acid bis[N2-(2-hydroxybenzoyl)hydrazide], 2',3-bis Examples include [[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide, and more preferably 2',3-bis[[3-[3,5- Di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide is mentioned.

Examples of the lubricant include hydrocarbon type, fatty acid type, fatty acid amide type, ester type, and alcohol type.

Examples of processing aids include ricinoleic acid, stearic acid, palmitic acid, lauric acid, salts or esters thereof, and polymethyl methacrylate.

(phase structure)
FIG. 2 is a diagram schematically showing the phase structure of the resin composition used for the outer skin layer of the cable of Embodiment 1. As shown in Figure 2, by using PVC and TPU as the base polymer (A) and adjusting the intensity of the electron beam required for crosslinking, a resin composition in which non-crosslinked TPU is dispersed as domains in a crosslinked PVC matrix can be obtained. Can be done. Squares indicate crosslinked PVC (including crosslinked CPE-containing PVC) 15, and black circles indicate non-crosslinked TPU16. According to such a resin composition, while maintaining resilience by mixing PVC and TPU, crosslinkability is maintained while suppressing the irradiation intensity of electron beams, and the collapse of TPU and PVC polymers is suppressed (electrical properties (improvement of heat resistance and cold resistance).

In order to obtain the phase structure shown in Figure 2, the volume fractions of PVC (which may contain chlorinated polyethylene) and components (B), (C), (D), and (E) must be must be greater than the TPU volume fraction. The dispersed diameter of TPU present as a domain layer can be varied in any way by controlling the viscosity, shear rate, and interfacial tension of both (PVC and TPU). Specifically, the diameter can be changed from about 0.01 to 100 μm.

(Content ratio)
The content ratios of components (A) to (D) in the resin composition are as follows.

First, the base polymer (A) preferably contains 20 to 230 parts by mass of TPU per 100 parts by mass of PVC. When TPU is 20 parts by mass or more, the restorability is improved, and when it is 230 parts by mass or less, flame retardancy and electrical properties are improved. It is more preferable to adjust TPU to 60 parts by mass or more and 150 parts by mass or less.

When chlorinated polyethylene is further added, it is preferable to contain 0 to 300 parts by mass of chlorinated polyethylene per 100 parts by mass of PVC. CPE is a polymer that may be added to adjust the flexibility, restorability, and flame retardance of the system, and PVC and TPU alone can achieve this performance. By controlling the content to 300 parts by mass or less, it is possible to suppress deterioration in handling properties during mixing.

The content of the plasticizer (B) is preferably 50 to 100 parts by mass based on 100 parts by mass of PVC. When the amount is 50 parts by mass or more, the resin composition can be prevented from becoming hard, and the handleability becomes good. In addition, by setting the amount to 100 parts by mass or less, the resin composition does not become sticky and has good handling properties.

Although the content of the stabilizer (C) is not particularly limited, metal soap tends to lower the hydrogen bond strength and urethane bond strength in the hard segment of TPU compared to hydrotalcite, and there is a risk that the heat resistance of the insulating layer will be impaired. . Therefore, from the perspective of stabilizing PVC and chlorinated polyethylene while maintaining high heat resistance, the content of metal soap should be reduced, while hydrotalcite should be added to ensure the effect of the stabilizer (C). It is better to increase the amount. Specifically, it is preferable that the content of metal soap is 2.3 parts by mass or less and the content of hydrotalcite is 11 parts by mass or more based on 100 parts by mass of PVC. The lower limit of the metal soap content is not particularly limited, but if it is too small, the resin composition will be colored or its properties will deteriorate, so it is preferably 0.01 part by mass or more.

Further, when epoxy soybean oil is used as the stabilizer (C), the content thereof is preferably 1 to 20 parts by mass based on 100 parts by mass of PVC.

The content of the flame retardant (D) is not particularly limited, but the total content of (d1) to (d4) is preferably 1 to 70 parts by mass based on 100 parts by mass of PVC. Further, the contents of each of (d1) to (d4) are not particularly limited as long as the total amount is within the above range, but each is preferably within the following ranges. (d1) is 0 to 40 parts by weight, (d2) is 0 to 20 parts by weight, (d3) is 0 to 20 parts by weight, and (d4) is 0 to 50 parts by weight.

(Preparation of resin composition)
The resin composition may be prepared by mixing the components (A) to (E) above as necessary and melting and kneading the mixture. The kneading may be carried out using a known kneading device such as a batch kneader such as a Banbury mixer or a pressure kneader, or a continuous kneader such as a twin-screw extruder.

Specifically, first, PVC, plasticizer (B), stabilizer (C), flame retardant (D), and other additives (E) are mixed and dried up, and when CPE is added, it is added. Thereafter, base pellets are obtained by kneading using a twin-screw extruder, a pressure kneader, or the like. Subsequently, the obtained base pellets and TPU are mixed and melt-kneaded using a twin-screw extruder, a pressure kneader, or the like. By performing such kneading, a resin composition can be formed. By preparing the resin composition in advance using base pellets, it becomes possible to facilitate the kneading operation. In order to shorten the kneading work, a pressure kneader or the like may be used to knead all at once. Specifically, when using a pressure kneader, PVC (including when CPE is added), plasticizer (B), stabilizer (C), flame retardant (D), and other additives (E) are mixed in the pressure kneader. Pour the mixture all at once and roughly knead in a low filling state. When the resin temperature in the tank rises to about 150°C, TPU pellets are added and kneaded. The main kneading is performed until the resin temperature in the tank reaches around 170°C.

(Crosslinking)
As described above, the resin composition is crosslinked from the viewpoint of improving the oil resistance of the outer skin layer and the anti-inflammatory stability during combustion. The crosslinking method employs electron beam crosslinking, and crosslinks the extruded resin composition by irradiating it with an electron beam of 0.5 to 8 Mrad. With such an electron beam irradiation intensity, PVC can be crosslinked and TPU can be made non-crosslinked. That is, in the outer skin layer, the gel fraction (degree of crosslinking) derived from TPU is not developed, and the necessary gel fraction can be developed mainly in PVC.

(Cable manufacturing method)
First, the conductor 11 is prepared, and a resin composition having ETFE (tetrafluoroethylene/ethylene copolymer), which is a fluororesin, is extruded using an extrusion molding machine so as to cover the periphery of the conductor 11, for example. , an insulating layer 12 of a predetermined thickness is formed, and an insulated wire 10 is obtained. Subsequently, the insulated wire 10 is crosslinked with an electron beam using an electron beam irradiation device. Thereafter, a shield layer 13 is formed around a plurality of insulated wires (for example, a core portion made of five two-strand insulated wires twisted together) using a braiding machine. Subsequently, the resin composition containing the components (A) to (E) described above is extruded using an extrusion molding machine so as to cover the periphery of the shield layer 13, thereby forming an outer skin layer 14 of a predetermined thickness. Subsequently, the outer skin layer 14 of the cable 1 is subjected to electron beam crosslinking using an electron beam irradiation device. Thereby, the cable 1 of this embodiment can be manufactured.

<Main effects of this embodiment>
According to this embodiment, one or more of the following effects can be achieved.

According to the cable of this embodiment, the resin composition forming the outer skin layer includes a base polymer (A), a plasticizer (B), a stabilizer (C), a flame retardant (D), and other additives (E). ), wherein the base polymer (A) contains a polyvinyl chloride resin (a1) and at least one adipate-based, lactone-based, and carbonate-based urethane thermoplastic elastomer (a2), The stabilizer (C) contains hydrotalcite (c1) and a metal soap (c2), and the flame retardant (D) contains a metal hydroxide (d1), a brominated flame retardant (d2), an amorphous The other additive (E) contains at least one of silica (d3) and antimony trioxide (d4), and is formed from a resin composition containing calcined clay. The fired clay is contained in an amount of 35 parts by mass or more based on 100 parts by mass of the polyvinyl chloride resin (a1). Further, the other additive (E) is formed from a resin composition containing a crosslinking aid. The crosslinking aid is contained in an amount of 3 parts by mass or more based on 100 parts by mass of the polyvinyl chloride resin (a1). By applying a resin mixture with this composition, a compound with the phase structure shown in Figure 2 can be obtained, and a high level of well-balanced flame retardancy, restorability, crosslinkability, electrical properties, heat resistance, and cold resistance can be obtained. be able to.

Specifically, the cable of this embodiment has high flame retardancy that allows it to pass the vertical flame retardant test VW-1 specified in the flame retardant standard UL1581. It also has high heat resistance that satisfies the 105°C rating in the UL standard. It also has high resilience so that it will not break when used as a cable for FA robots. Furthermore, it has high cold resistance such that it does not break even at -20°C when subjected to the embrittlement test described below, and its electrical properties have a volume resistivity of 5E+13 at room temperature. As for crosslinkability, a material having a gel fraction (conditions: THF (tetrahydrofuran) at 70° C., 20 hours) of 30% or more can be obtained.

In this embodiment, a case has been described in which the resin compositions of the above components (A) to (E) are used for the outer skin layer of a cable, but the present invention is not limited thereto. For example, the resin compositions of components (A) to (E) above can also be used for an insulating layer of an insulated wire. In addition, an insulated wire in which the resin compositions of the above (A) to (E) components are used for the insulating layer is used as the core part, and the resin composition of the above (A) to (E) components is used as the outer skin layer around the core part. It is also possible to use a cable using

Next, the present invention will be explained in more detail based on Examples, but the present invention is not limited to these Examples.

<Materials>
In this example, the materials used for the flame-retardant resin composition for the outer skin layer are as follows.

The following polyvinyl chloride resin was used.
・Polyvinyl chloride resin (product name "TH-1700", manufactured by Taiyo PVC Co., Ltd., average degree of polymerization 1600-1800)
The following was used as the adipate type urethane thermoplastic elastomer.
・Adipate type TPU (product name "P25MRWJE", manufactured by Nippon Miractran Co., Ltd., Shore A hardness 90)
The following was used as the chlorinated polyethylene.
・Chlorinated polyethylene (product name: "Elasuren 352GB", manufactured by Showa Denko, chlorine content: 34% to 37%)
The following was used as the plasticizer (B).
・Di-2-ethylhexyl trimellitate (TOTM) (product name “T08”, manufactured by Kao Corporation)
The following was used as the hydrotalcite of the stabilizer (C).
・Hydrotalcite (product name "HT-1", manufactured by Sakai Chemical Co., Ltd.)
The following metal soap was used as a stabilizer.
・Zinc stearate (product name “SZ-P”, manufactured by Sakai Chemical Co., Ltd.)
・Calcium stearate (product name "SC-P", manufactured by Sakai Chemical Co., Ltd.)
The following was used as the epoxidized soybean oil as a stabilizer.
・Epoxidized soybean oil (Newsizer 510R, manufactured by ADEKA)
The following were used as other components of the stabilizer.
・Stabilizing aids (including β-diketones, etc.)
The following was used as the metal hydroxide (d1) of the flame retardant (D).
・Untreated aluminum hydroxide (product name "BF013", manufactured by Nippon Light Metal Co., Ltd.)
The following was used as the brominated flame retardant (d2) of the flame retardant (D).
- Brominated flame retardant (decabromodiphenylethane, product name "Cytex 8010", manufactured by Albemarle Co., Ltd., average particle size 5.6 μm)
The following was used as the amorphous silica (d3) of the flame retardant (D).
・Amorphous silica (product name "SIDISTAR120U", manufactured by Elkem Co., Ltd., average particle size 0.15 μm)
The following was used as antimony trioxide (d4) of the flame retardant (D).
・Antimony trioxide (product name "NANO200", manufactured by Changde Shinzhou Co., Ltd., average particle size 0.8 μm)
The following were used as other additives (E).
・Crosslinking aid (trimethylolpropane trimethacrylate, product name "TMPT", manufactured by Shin Nakamura Chemical Co., Ltd.)
・Calcined clay (product name "SP#33", manufactured by BASF)
・Surface treatment fired clay (product name “Translink 77”)
・Coloring agent black (product name "NBP2425", manufactured by Nihonbix Co., Ltd.)
・Coloring agent white (product name “Titanium White R820”, manufactured by Ishihara Sangyo Co., Ltd.)
・Antioxidant (product name “AO-25”, manufactured by ADEKA Co., Ltd.)
The raw materials used are summarized in Table 1.

<Example 1A>
First, a conductor, a resin composition for forming an insulating layer, and a resin composition for forming an outer skin layer were prepared.

A 28AWG (19/0.08) TA conductor was used as the conductor.

The compositions shown in Table 2 were used as the resin compositions for forming the outer skin layer. Furthermore, although the compositions shown in Table 2 were used as the resin compositions for forming the insulating layer, other resin compositions for forming the insulating layer may be used.

A resin composition was prepared by mixing and kneading the compositions shown in Table 2. Specifically, as the base polymer (A), 100 parts by mass of polyvinyl chloride resin, 63 parts by mass of adipate type TPU, 60 parts by mass of TOTM as the plasticizer (B), and hydrotalcite as the stabilizer (C). 11.7 parts by mass, 1.1 parts by mass of zinc stearate which is a metal soap (c2), 1.2 parts by mass of a stabilizing agent, and a metal hydroxide (d1) as a flame retardant (D). 5.0 parts by mass of a certain untreated aluminum hydroxide, 5 parts by mass of brominated flame retardant (d2), 5 parts by mass of amorphous silica (d3), 5 parts by mass of antimony trioxide (d4), and Other additives (E) include 5 parts by mass of crosslinking aid, 44.5 parts by mass of calcined clay, 5.9 parts by mass of colorant black, and 0.5 parts by mass of colorant white, totaling 312. 4 parts by mass were kneaded to prepare the resin composition of Example 1. The resin composition was prepared by melt-kneading using a pressure kneader at a take-out temperature of 165°C, cutting into strands, and then drying at 80°C for 2 hours.

Next, using a 40 mm extruder for manufacturing insulated wires, a resin composition for forming an insulating layer was extruded around the conductor to form an insulating layer with a thickness of 0.2 mm. Thereafter, irradiation was performed using an electron beam irradiation equipment at an irradiation intensity of 3.5 Mrad to obtain an insulated wire. Thereafter, five two-stranded insulated wires were twisted together to form a core part. Then, a shield layer was formed around the core by twisting (right twist) the staple yarn and polyester tape (1/4 wrap) using a braiding machine. Subsequently, a resin composition for forming an outer skin layer was extruded around the shield layer by a tube extrusion method using a 65 mm single-screw extruder for manufacturing insulated wires to form an outer skin layer with a thickness of 1 mm. Thereafter, irradiation was performed using an electron beam irradiation facility at an irradiation intensity of 3.5 Mrad. In this way, the insulated wire and cable of Example 1A were produced.

<Examples 2 to 7>
In Examples 2 to 7, cables were produced in the same manner as in Example 1A, except that the types and blending amounts of components (A) to (E) were changed as shown in Table 2.

<Comparative Examples 1 to 4>
Comparative Example 1 is an example in which both the insulated wire and the cable were produced without electron beam irradiation crosslinking, and Comparative Examples 2 to 4 were verified by varying the amount of crosslinking aid and firing clay, which is component (E). It is something. The method for producing the compound and the method for extruding the insulated wire and cable were carried out in the same manner as in Example 1A.

<Example 1B, 1C, Reference Example 1>
Examples 1B, 1C, and Reference Example 1 were tested by varying the electron beam irradiation intensity in order to understand the influence of irradiation intensity on crosslinking properties.

<Evaluation>
Regarding the produced insulated wires, cables, and composition sheets of Examples 1A, 1B, 1C, 2 to 7, Comparative Examples 1 to 4, and Reference Example 1, heat resistance, flame retardance, restorability, electrical properties, crosslinking properties, and Cold resistance was evaluated. Each evaluation was performed as follows. The evaluation results are shown in Table 2. In Table 2, the mark ○ means pass, and the mark x means fail.

(Heat-resistant)
Heat resistance was evaluated by a test based on UL1581. Specifically, a sample (about 100 mm in length) of the produced insulated wire with only an insulating layer was exposed to a gear oven at 136°C for 168 hours, and the initial tensile strength and elongation and the post-exposure tensile strength and elongation were measured. compared with. Then, calculate the residual tensile strength (%) and residual elongation (%) using the following formula, and those with a residual tensile strength of 70% or more and a residual elongation of 45% or more are considered "passed". Items that did not satisfy any of these criteria or items that did not meet any of these criteria were deemed to be "fails."

Tensile strength residual rate (%) = 100 × (Tensile strength after the above exposure) / (Initial tensile strength)
Remaining elongation rate (%) = 100 x (elongation after the above exposure) / (initial elongation)

(Flame retardance)
Flame retardancy was evaluated by a test based on UL1581. Specifically, the fabricated insulated wires and cables (approximately 500 mm in length) were subjected to the vertical flame retardant test VW-1 specified by UL1581 three times, and those that met the standard all three times were deemed to have passed. Those who did not meet the criteria even once were deemed to have failed. Items in which either the insulated wire or cable failed were also rejected.

(Resilience)
Restorability was evaluated by the following method. First, sample pieces were prepared by punching out the insulation layer from which the conductor was removed from each insulated wire and the outer skin layer taken from the cable into a dumbbell shape. Next, using a tensile testing machine, the insulating layer and sample piece were stretched 100% under the conditions of a gauge line spacing of 25 mm and a tensile speed of 200 mm/min, and then the testing machine was stopped. After that, the dumbbells were removed and the test piece was stretched for 100%. After seconds, the extent to which the 25 mm distance between the marked lines had expanded (X value) was measured. Then, the degree of restoration (Y) was calculated from the following formula. Note that "*" means a product. In this example, a Y value of 70 or more was considered a pass, and a Y value of less than 70 was a fail. Note that the degree of recovery Y has been confirmed to be an index of recovery properties since it shows a certain degree of correlation with the rebound modulus.
Y=-4*X+200

(Electrical characteristics)
Electrical properties were evaluated by the following method. First, the composition shown in Table 2 was kneaded using a 6-inch mixing roll, and a 1 mm thick composition sheet was prepared under the conditions of preheating at 180° C. for 3 MIN/2 Mpa, pressure heating for 2 MIN/10 Mpa, and cooling for 5 MIN. Thereafter, in Examples 1 to 7 and Comparative Examples 2 to 4, the irradiation intensity was adjusted to the values shown in Table 2 using electron beam irradiation equipment to obtain crosslinked composition sheets subjected to irradiation crosslinking treatment. The volume resistivity at room temperature was measured using the obtained sheet (Comparative Example 1 was an uncrosslinked sheet), and materials exhibiting a value of 5E+13 Ω·cm or more were judged to be acceptable, and those less than that were judged to be unacceptable.

(Crosslinkability)
A conductor was removed from the insulating layer produced by electron beam irradiation to prepare a cut sample having a side of 1 mm or less. Thereafter, the gel fraction was measured using THF (tetrahydrofuran at 70°C for 20 hours). The gel fraction is the numerical value obtained by dividing the mass obtained by drying the residual amount of the gel mesh (the amount that has not passed through the 40 mesh gel mesh) by the initial quantity. Those whose remaining amount (gel fraction) was 30% or more with respect to the initial mass were considered to be passed, and those whose residual amount (gel fraction) was less than 30% were judged to be rejected.

(cold resistance)
Cold resistance was evaluated by the following test. Specifically, a destructive test was conducted using an insulating layer obtained by removing the conductor from the produced insulated wire and a tube obtained by removing the outer skin layer from the cable. In this example, a sample that did not break even at a temperature of -20°C was judged as "pass", and a sample that broke at a temperature higher than that was judged as "fail".

<Evaluation results>
Table 2 summarizes the evaluation results of the cable's heat resistance, flame retardance, restorability, electrical properties, and cold resistance.

Comparative Example 1 was a sample that was not subjected to electron beam crosslinking, and could not pass the crosslinking test as well as the flame retardance test. This is because the flame retardancy of the insulated wire passed, but the flame retardance of the cable failed.

In Comparative Examples 2 to 4, the amount of crosslinking aid and amount of fired clay were below the specified amount, so it was not possible to adjust the balance of crosslinkability, electrical properties, and cold resistance. Comparative Example 4 also failed in heat resistance, but this is considered to be due to the type and content of the metal soap.

In Examples 1 to 7, it was confirmed that heat resistance, flame retardance, restoring properties, electrical properties, crosslinking properties, and cold resistance were obtained in a well-balanced manner at a high level.

Moreover, the gel fraction of Comparative Examples 2 and 4 was 0%. This suggests that TPU is not crosslinked, and the TPU content (TPU amount * 100/total amount) is 45% or more (46.5% for Comparative Example 2, 45% for Comparative Example 4). It was found that cross-linking on the PVC side was also inhibited.

(summary)
As described above, it has been found that the resin composition containing the components (A) to (E) of the present embodiment is suitable for use as an insulating layer of an insulated wire and an outer skin layer of a cable.

Specifically, the resin composition includes a base polymer (A), a plasticizer (B), a stabilizer (C), a flame retardant (D), and other additives (E). Contains a vinyl chloride resin (a1) and at least one adipate-based, lactone-based, and carbonate-based urethane thermoplastic elastomer (a2), and as stabilizers (C), hydrotalcite (c1) and metal soap (c2) The flame retardant (D) contains at least one of metal hydroxide (d1), brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4), and the other Additive (E) includes calcined clay. The fired clay contains 35 parts by mass or more based on 100 parts by mass of the polyvinyl chloride resin (a1).

Further, as for the irradiation intensity of the electron beam to the insulating layer of the insulated wire and the outer skin layer of the cable, as in Examples 1B, 1C, and Reference Example 1, it is preferable to irradiate the electron beam in a relatively low irradiation area. Specifically, about 0.5 to 8 Mrad is preferable. This is because if it is less than 0.5, the crosslinkability will fail (Reference Example 1), and if it is more than 8.1 Mrad, the electrical properties will fail.

By applying such a resin composition to the outer skin layer of a cable or the insulation layer of an insulated wire, a compound with the phase structure shown in Figure 2 can be obtained, and it has excellent flame retardancy, heat resistance, restorability, electrical properties, and crosslinking. Cables and insulated wires that meet the characteristics and cold resistance can be obtained. Such cables and insulated wires are expected to be applied to the field of FA robots.

The present invention is not limited to the embodiments and examples described above, and can be modified in various ways without departing from the gist thereof.

1 Cable 10 Insulated wire 11 Conductor 12 Insulating layer 13 Shield layer 14 Outer layer 15 Cross-linked PVC
16 Non-crosslinked TPU

Claims (6)

A cable comprising an insulated wire and an outer skin layer coated around the insulated wire,
The insulated wire includes a conductor and an insulating layer coated around the conductor,
The outer skin layer is formed from a resin composition containing a base polymer (A), a plasticizer (B), a stabilizer (C), a flame retardant (D), and other additives (E),
The base polymer (A) includes a polyvinyl chloride resin (a1) and at least one adipate-based, lactone-based, and carbonate-based urethane thermoplastic elastomer (a2),
The stabilizer (C) includes hydrotalcite (c1) and metal soap (c2),
The flame retardant (D) contains at least one of metal hydroxide (d1), brominated flame retardant (d2), amorphous silica (d3) and antimony trioxide (d4),
The other additive (E) includes fired clay,
The fired clay contains 35 parts by mass or more based on 100 parts by mass of the polyvinyl chloride resin (a1) ,
In the cable , the outer skin layer is crosslinked with an electron beam having an irradiation intensity of 0.5 Mrad or more and 8 Mrad or less . The cable according to claim 1,
The other additive (E) includes a crosslinking aid,
The cable, wherein the crosslinking aid is contained in an amount of 3 parts by mass or more based on 100 parts by mass of the polyvinyl chloride resin (a1). The cable according to claim 2,
The cable, wherein the crosslinking coagent is any of trimethylolpropane trimethacrylate, triallyl isocyanurate, or triallyl cyanurate . The cable according to any one of claims 1 to 3,
The cable, wherein the base polymer (A) includes chlorinated polyethylene. The cable according to any one of claims 1 to 4 ,
A cable in which a gel fraction derived from the urethane thermoplastic elastomer (a2) is not expressed in the outer skin layer. An insulated wire comprising a conductor and an insulating layer coated around the conductor,
The insulating layer is formed from a resin composition containing a base polymer (A), a plasticizer (B), a stabilizer (C), a flame retardant (D), and other additives (E),
The base polymer (A) includes a polyvinyl chloride resin (a1) and at least one adipate-based, lactone-based, and carbonate-based urethane thermoplastic elastomer (a2),
The stabilizer (C) includes hydrotalcite (c1) and metal soap (c2),
The flame retardant (D) contains at least one of metal hydroxide (d1), brominated flame retardant (d2), amorphous silica (d3) and antimony trioxide (d4),
The other additive (E) includes fired clay,
The fired clay contains 35 parts by mass or more based on 100 parts by mass of the polyvinyl chloride resin (a1) ,
The insulating layer is crosslinked by an electron beam with an irradiation intensity of 0.5 Mrad or more and 8 Mrad or less,
Insulated wire.

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