JPH10233124A - Cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cable for use in an automobile, robot, electronic equipment, and the like, that is excellent in the airtightness of its connection with a terminal and in mechanical strength and flexibility. SOLUTION: In a cable having two or more cover layers provided on the outside of a multiconductor stranded wire comprising a plurality of insulating conductors twisted together, the outermost cover layer has an average thickness of 0.25 to 0.7mm and is constructed of a crosslinked material obtained when a resin composition whose base resin comprises 100-30wt.% thermoplastic polyurethane and 0-70wt.% polyester elastomer or ethylene-glycidyl methacrylate copolymer is extrusion molded and is then electron-ray crosslinked at a degree of crosslinking of 5-40%. Therefore, the cable has excellent mechanical characteristics and flexibility and is particularly excellent in terminal processability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable used for automobiles, robots, electronic devices, and the like, and more particularly, to a cable having excellent mechanical properties and flexibility. After connecting to the terminal, etc., in order to keep this connection part air-tight or water-tight, it is molded with polyethylene terephthalate or polybutylene terephthalate.
The present invention relates to a cable suitable for performing a banding process.

[0002]

2. Description of the Related Art As an insulating layer of a cable used for automobiles, robots, electronic devices, and the like, a thermoplastic polyurethane composition having good mechanical properties and flexibility is employed as a coating material. A sensor such as this
When connecting equipment parts and electrode terminals such as those described above, the connection part and its surroundings are molded airtight or watertight with a resin mold (molded body) for protection. In order to ensure air-tightness and water-tightness with the resin mold, ease of molding,
Polyethylene terephthalate and polybutylene terephthalate having excellent mechanical strength are frequently used as molding materials.

[0003]

However, depending on the selection of the covering material of the cable and the molding material, the difference in the heat shrinkage between the materials causes the formation of the cable in the heating and cooling process during the terminal processing or use. There is a gap at the body interface,
There is a problem that moisture infiltrates from a gap generated at the interface. If moisture invades from the gap created at the interface, the conductors of the cable will corrode and the performance of the connected equipment parts will deteriorate, and other problems will occur.Therefore, various seals are required to maintain airtightness and watertightness. Countermeasures are required. For this reason, the workability at the time of terminal processing becomes extremely complicated, and the work required a high degree of skill.

In order to solve such a problem, it is conceivable that the covering material of the cable is made of the same or similar material as the mold material. However, these resin materials have high moldability as a covering material of the cable. Poor, there is also a problem with the flexibility required for the electric wire, and it is not practical because the material is expensive. An object of the present invention is to maintain the air-tightness and water-tightness of the interface between a cable and a molded body without taking any special sealing measures to maintain the air-tightness and water-tightness, and to corrode the conductor of the cable. It is an object of the present invention to provide a cable which is capable of preventing deterioration of performance of connected equipment components and has excellent heat resistance and low temperature characteristics.

[0005]

In order to achieve the above object, the present invention provides: 2 on the outside of a multi-core stranded wire consisting of multiple insulated conductors
In a cable provided with at least one coating layer, the outermost layer of the coating layer has an average thickness of 0.25 mm to 0.7 mm.
The outermost layer is a thermoplastic resin alone or a mixture of a thermoplastic polyurethane and a polyester elastomer or an ethylene-glycidyl methacrylate copolymer or a mixture thereof, which is 70% by weight or less. It is an object of the present invention to provide a cable characterized in that the resin composition is extruded and irradiated with an electron beam to constitute a crosslinked product having a degree of crosslinking of 5 to 40%.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the cable of the present invention, two or more coating layers are provided on a multi-stranded stranded insulated conductor. In the production of the cable of the present invention, the coating layer provided on the multifilamentary stranded wire of the insulated conductor may be a plurality of layers simultaneously extruded or coated with the inner layer and then coated with the next outer layer. At that time, the average thickness of the outermost layer is set to 0.25 mm to 0.7 mm. When the thickness of the outermost layer is larger than 0.7 mm, the heat resistance of the cable is significantly reduced. On the other hand, if it is smaller than 0.25 mm, the adhesion to the lower layer is significantly reduced, and the airtightness at the interface is greatly reduced.
It is in the range of 3 mm to 0.65 mm.

FIG. 1 shows an embodiment of the cable of the present invention.
In FIG. 1, reference numeral 1 denotes a multi-core stranded wire. The multi-core stranded wire 1 is made of, for example, polyethylene on a stranded wire conductor 1a obtained by twisting 20 tinned soft copper wires having an outer diameter of 0.18 mmφ and finishing the conductor diameter to 1 mmφ. , A plurality of (two in FIG. 1) insulated conductors 1 provided with an insulating layer 1b made of polyvinyl chloride or the like. 2 is a coating layer covering the multi-core stranded wire 1,
The coating layer 2 is composed of a plurality of layers (two layers in FIG. 1).
a is a resin composition containing a thermoplastic polyurethane as a base resin, or a group consisting of an ethylene / α-olefin copolymer and an ethylene / vinyl acetate copolymer having a density of 0.86 to 0.90 g / cm ^3. It is composed of a resin composition containing at least one selected base resin. The outer layer 2b is formed by extruding a resin composition containing 100 to 30% by weight of a thermoplastic polyurethane and 0 to 70% by weight of a polyester elastomer and cross-linking with an electron beam, or 100 to 30% by weight of a thermoplastic polyurethane. %, Ethylene / glycidyl methacrylate copolymer 0
A resin composition having a base resin content of about 70% by weight is formed by extrusion molding and electron beam crosslinking. The degree of cross-linking by electron beam cross-linking in the present invention is in the range of 5 to 40% from the viewpoint of adhesion to a mold material made of polyethylene terephthalate or polybutylene terephthalate. Incidentally, reference numeral 3 in the drawing denotes a cable.

In a first embodiment of the cable of the present invention, the outermost layer of the coating is formed of a thermoplastic polyurethane alone or a resin composition comprising a base resin obtained by blending a thermoplastic polyurethane with a polyester elastomer. The amount of the urethane resin is preferably 30% by weight or more. If the content of the urethane resin is less than 30% by weight, the adhesion to polyethylene terephthalate or polybutylene terephthalate, which is a molding material constituting the cable end, becomes weak, and the low-temperature characteristics and water resistance of the cable become poor. It is because it falls. This is because, when the polyester elastomer is blended with the thermoplastic polyurethane, the adhesive strength with polyethylene terephthalate or polybutylene terephthalate as a molding material is improved. When the polyester elastomer is blended, the blending amount is preferably not more than 70% by weight. If the amount of the polyester elastomer exceeds 70% by weight, the hot water resistance and the hydrolysis resistance of the cable are reduced, and the adhesive strength with polyethylene terephthalate or polybutylene terephthalate is also reduced. Although the adhesive strength with the molding material can be obtained only with thermoplastic polyurethane, the adhesion to the molding material is greatly improved by blending 10% by weight or more of the polyester elastomer.

In a second embodiment of the present invention, the outermost coating layer is formed of a resin composition comprising a base resin obtained by blending an ethylene-glycidyl methacrylate copolymer with a thermoplastic polyurethane. By blending the ethylene-glycidyl methacrylate copolymer, it is possible to improve the adhesive strength with polyethylene terephthalate or polybutylene terephthalate as a molding material. The content of the ethylene / glycidyl methacrylate copolymer is 70
% By weight or less is preferred. In this case, if the amount of the ethylene / glycidyl methacrylate copolymer exceeds 70% by weight, the low-temperature characteristics of the cable deteriorate, and the adhesion to the polyethylene terephthalate or polybutylene terephthalate mold material also decreases. To do that. As described above, the adhesive strength with the molding material can be obtained only with the thermoplastic polyurethane, but the adhesion to the molding material is greatly improved by blending the ethylene-glycidyl methacrylate copolymer at 10% by weight or more. From thing 1
It is preferable to add 0% by weight or more.

In the cable of the present invention, the outermost layer of the coating is crosslinked by electron beam crosslinking, and the degree of crosslinking is from 5 to 4.
0%. The reason for setting the degree of crosslinking of the outermost layer to 5 to 40% is that
If the degree of cross-linking is less than 5%, the heat resistance of the cable is remarkably reduced, for example, the outermost layer is melted at a low temperature. Is significantly reduced.

In any of the above embodiments, the coating material for the inner layer is preferably a resin composition whose main component is thermoplastic polyurethane. By using the thermoplastic polyurethane as the coating material, the coating layers of the inner layer and the outer layer adhere to each other, and it is possible to maintain good airtightness and repetitive bending resistance therebetween. Furthermore, an ethylene / α-olefin copolymer having a density of 0.86 to 0.90 g / cm ³ and an ethylene / α-olefin
It is preferable to use a resin composition using any one of vinyl acetate copolymers or a mixture thereof as a base resin. When these resins are used, it is possible to form a cable at low cost while maintaining the airtightness and the repeated bending characteristics between the inner layer and the outer layer.

The thermoplastic polyurethane used in the present invention includes polyester-based urethane resins (adipate-based, caprolactone-based, and polycarbonate-based) and polyether-based urethane resins. Polyether-based urethane resins are preferred in terms of properties and the like.
The hardness (type A durometer, 1 kgf) of the thermoplastic polyurethane is preferably 90 or less.

As the polyester elastomer used in the present invention, an ester copolymer of an aromatic polyester such as polybutylene terephthalate, polybutylene isophthalate and polyethylene terephthalate and a polyether is preferable. For example, there are a copolymer of polytetramethylene ether glycol (PTMG) and polybutylene terephthalate (PBT), a copolymer of PTMG and polybutylene isophthalate (PBI), and a copolymer of PTMG and polyethylene terephthalate (PET). .

The ethylene-glycidyl methacrylate copolymer used in the present invention includes, for example, ethylene-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate-vinyl acetate terpolymer. And terpolymers of ethylene, glycidyl methacrylate, and methyl acrylate. Two or more of these may be used in combination. The melt flow rate (MFR) of the ethylene / glycidyl methacrylate copolymer is 2 to 10 g / 10 min. (Load 216kgf, temperature 1
(90 ° C.). As such a material, for example, “Bonfast” (trade name, manufactured by Sumitomo Chemical Co., Ltd.) is commercially available, and the characteristics required for a cable such as mechanical characteristics and flexibility are sufficiently considered. And various grades of commercial products can be appropriately selected and used.

The ethylene / α-olefin copolymer used in the present invention includes ethylene and propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene and 1-dodecene. It is a copolymer with at least one kind of α-olefin, and preferably has a density of 0.86 to 0.90 g / cm ³ from the viewpoint of crosslinkability and elasticity.

The ethylene / vinyl acetate copolymer used in the present invention preferably has a vinyl acetate content of 10 to 30% by weight from the viewpoint of crosslinkability and elasticity. Ethylene / α-olefin copolymer and ethylene / vinyl acetate copolymer can improve the heat resistance by crosslinking, and have a high melting point such as polyethylene terephthalate and polybutylene terephthalate. In the case of molding with, crosslinking is performed.

As a method for crosslinking the coating layer, a crosslinking method by electron beam irradiation is preferable. In the electron beam crosslinking method, crosslinking is performed by irradiating the resin composition with an electron beam after extrusion molding. The dose of the electron beam is suitably from 1 to 30 Mrad. When the resin composition used in the present invention is crosslinked, it is necessary to add a crosslinking assistant of a polyfunctional monomer (trimethylolpropane trimethacrylate, triallyl cyanurate, etc.) to the resin composition. It is. Although the number of parts varies depending on the type of the crosslinking aid, 0.2 parts by weight based on 100 parts by weight of the base resin
１５15 parts by weight is an appropriate amount. The degree of crosslinking can be controlled by appropriately selecting the irradiation dose, the type of the crosslinking aid, the amount of the crosslinking aid, and the like.

In the resin composition of the inner layer and the outer layer of the cable according to the present invention, various additives generally used in insulated conductors and cables, for example, antioxidants,
A metal deactivator, a flame retardant, a dispersant, a colorant, a filler, a lubricant and the like can be appropriately compounded within a range that does not impair the object of the present invention. As antioxidants, 4.4′-dioctyl diphenylamine, N,. '-Diphenyl-p-phenylenediamine, 2,2,4-trimethyl-1,. An amine antioxidant such as a polymer of dihydroquinoline, pentaerythrityl-tetrakis (3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate),
Octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl- Phenolic antioxidants such as 4-hydroxybenzyl) benzene, bis (2-methyl-4- (3-n-alkylthiopropionyloxy) -5-t-butylphenyl) sulfide, 2-mercaptobenzimidazo- And zinc salts thereof, and sulfur-based antioxidants such as pentaerythritol-tetrakis (3-lauryl-thiopropionate).

Examples of the metal deactivator include N, N'-bis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hydrazine, 3- (N-salicyloyl) amino-1, 2,4-triazole, 2,2 ^, -
Oxamidobis- (ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) and the like. Examples of the flame retardant include tetrabromobisphenol A (TBA), decabromodiphenyl oxide (DBDPO), and octabromodiphenyl ether (O
BDPE), hexabromocyclododecane (HBC
D), bistribromophenoxyethane (BTBP)
E), tribromophenol (TBP), ethylenebistetrabromophthalimide, TBA / polycarbonate oligomer, brominated polystyrene, brominated epoxy, ethylenebispentabromodiphenyl, chlorinated paraffin, dodecachloro Examples include halogen-based flame retardants such as cyclooctane, inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide, and phosphorus-based flame retardants such as phosphoric acid compounds, polyphosphoric acid compounds, and red phosphorus compounds.

Examples of the flame retardant aid and filler include carbon, clay, zinc oxide, tin oxide, magnesium oxide, molybdenum oxide, antimony trioxide, silica, talc, calcium carbonate, magnesium carbonate, zinc borate and the like. can give.

[0021]

【Example】

(Examples, Comparative Examples) A low-density polyethylene was extrusion-coated on a conductor (tin-plated soft copper stranded wire with a conductor diameter of 1 mmφ: 20 wires / 0.18 mmφ) to form an insulating layer with an outer diameter of 1.7 mm. , With an acceleration voltage of 500 keV and a dose of 20 M
Two insulated conductors obtained by irradiating a rad electron beam and cross-linking the insulating layer were twisted to prepare a multi-core stranded wire 1 shown in FIG.
Next, a 40 mmφ extruder (L /
D = 25), and the resin composition A or B having the composition shown below was extrusion-coated so as to have an outer diameter of 4.2 mmφ and appropriately crosslinked to form a coating inner layer 2a. Next, after coating the coating material shown in Table 1 on the outside of the extrusion coating inner layer 2a by extrusion so as to have a coating outer diameter shown in Table 1, the coating outer layer 2b was irradiated with an electron beam at an irradiation dose shown in Table 1. The cable 3 was completed.

[0022] The following components were used for the above composition and each component shown in Table 1. (1) Urethane resin (E-385) Polyether-based urethane resin manufactured by Nippon Miractran Co., Ltd. (2) Polyester elastomer Polybutylene terephthalate-based elastomer Hytrel 2300X06 Toray DuPont Co., Ltd. (3) Ethylene glycidyl methacrylate Copolymer Bond First E Sumitomo Chemical Co., Ltd.

(4) Crosslinking aid Trimethylolpropane trimethacrylate (Shin Nakamura Chemical Co., Ltd.) (5) Flame retardant Cytex 8010 Ethylene bispentabromobiphenyl Albemarle (6) Antioxidant Irganox 1076 (18) Ethylene / vinyl acetate copolymer manufactured by Mitsui / Dupont Polychemical Co., Ltd. Evaflex V527-4 Vinyl acetate content 17% by weight Melt flow rate 0.8 g / 10 min. Density 0.94g / cm ³ Du Pont-Toray Co., Ltd.

Various characteristics of the obtained cables were evaluated by the following test methods. (1) Degree of crosslinking Xylene is used for polyester elastomer, and xylene is used for thermoplastic polyurethane as dimethylformamide and ethylene copolymer having glycidyl methacrylate for 24 hours according to JIS C 3005. The gel fraction after extraction and drying was measured. When the extraction solvent was different between the two polymer blend systems, the gel fraction was measured by extracting and drying once with one solvent and then extracting and drying with another solvent. (2) Low-temperature characteristics After the cable was wound five times around a 45 mmφ mandrel at −65 degrees, the presence or absence of cracks was observed. The results were indicated by the number of passes. (3) Heat resistance After winding the cable around the mandrel of its own diameter,
After heating for 0 minutes, the presence or absence of melting was confirmed. Results are "melted"
Is indicated by "x", and "no melting" is indicated by "o". (4) Airtightness of Terminal As shown in FIG. 2, the coating layers 2 and 1b of the cable were removed to expose the conductor 1a, and the electrode terminal 5 was connected to the end. Next, the connection portion and the vicinity thereof were injection-molded with polybutylene terephthalate (manufactured by Dainippon Ink) to form a resin molded body 4 to protect the connection portion. This cable was subjected to a heat cycle test of 10 cycles, with 120 ° C. × 1 hour and −40 ° C. × 1 hour as one cycle. After that, compressed air of 2 atm is injected from the terminal opposite to the resin molded body side, and there is no leakage from the resin molded body side,
It was immersed in water, and airtightness was confirmed by the presence or absence of air bubbles. The test was carried out on 5 samples, and when all passed, it was evaluated as ○, and when any of the samples failed, it was evaluated as x.

(5) Observation of Adhesive Surface and Peeling Strength Evaluation of adhesiveness was performed by preparing a sample as follows. (1) Dividing the coating layer of the cable of a predetermined length into two in the longitudinal direction,
Remove the insulated conductor, (2) Set the semicircular coating layer into two parts in a mold, and (3) Inject polybutylene terephthalate (manufactured by Toray) into the mold and put it on the coating layer. Polybutylene terephthalate was molded. The obtained resin molded body was subjected to a peel test. In the peeling test, the cable coating layer was formed at an angle of 90 ° from the molded product of polybutylene terephthalate.
The film was peeled off at a speed of 0 mm / min, and the strength at that time was measured. In addition, it was checked whether or not the covering material of the cable was present on the polybutylene terephthalate surface on the peeled surface. The case where a large amount of aggregates of the coating resin composition was present at the bonding interface between the polybutylene terephthalate and the coating layer of the cable was defined as "most" or "high" according to the ratio, and the case where a small amount was present was defined as "small". The case where it did not exist was represented as "none". The above evaluation results are also shown in Tables 1, 2, and 3.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

In each of the embodiments, low-temperature characteristics, heat resistance,
Excellent airtightness and adhesion (peel strength) of the terminal. On the other hand, in Comparative Example 31, the degree of cross-linking was too high and the terminal airtightness was poor, and in Examples 32-34, the heat resistance was poor due to lack of cross-linking or insufficient cross-linking degree. Because of the small thickness, the meat was cut and the appearance was poor.
Since the blending ratio of the thermoplastic polyurethane was small, the terminal airtightness was poor, and none of them satisfied the required characteristics, and did not meet the purpose of the present invention.

[0030]

According to the cable of the present invention, the outermost layer of the multi-layer coating is made of thermoplastic polyurethane 100 to 30.
% By weight of a polyester elastomer or / and an ethylene / glycidyl methacrylate copolymer
Weight percent of the base resin composition, and the average thickness of the outermost layer was III. It is extruded to a thickness of 25 mm to 0.7 mm and cross-linked with an electron beam so as to have a degree of crosslinking of 5 to 40%. Therefore, it has high adhesion to polyethylene terephthalate or polybutylene terephthalate resin molding material. , The air-tightness and water-tightness of the interface with the terminal molded body are sufficiently maintained, the corrosion of the cable conductor and the deterioration of the performance of the connected equipment parts can be prevented, and a cable excellent in heat resistance and low-temperature characteristics can be provided at a low cost. It has an effect and can be used for automobiles and electronic devices stably over time.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cable according to the present invention.

FIG. 2 is an explanatory view showing a state in which a resin molded body is formed at a terminal of the cable of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulated conductor 1a Conductor 1b Insulating layer 2 Coating layer 3 Cable 4 Resin molding 5 Electrode terminal

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Yamada 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd.

Claims (4)

[Claims] In a cable provided with two or more coating layers outside a multifilamentary stranded wire in which a plurality of insulated conductors are twisted, an outermost layer of the coating layers has an average thickness of 0.25 mm or more.
0.7 mm, and the outermost layer is made of thermoplastic polyurethane 10
0-30% by weight and polyester elastomer 0-7
A cable comprising a crosslinked product having a degree of crosslinking of 5 to 40% by extruding a resin composition containing 0% by weight of a base resin and irradiating the resin composition with an electron beam. 2. A cable in which two or more coating layers are provided outside a multifilamentary stranded wire in which a plurality of insulated conductors are twisted, wherein the outermost layer of the coating layers has an average thickness of 0.25 mm or more.
0.7 mm, and the outermost layer is made of thermoplastic polyurethane 10
A resin composition containing 0 to 30% by weight and 0 to 70% by weight of an ethylene / glycidyl methacrylate copolymer is extruded and irradiated with an electron beam to reduce the degree of crosslinking to 5 to 40%.
A cable characterized by comprising a crosslinked product of the above. 3. The cable according to claim 1, wherein a resin composition containing thermoplastic polyurethane as a base resin is used for the inner layer of the coating layer. 4. The inner layer of the coating layer has a density of 0.86 to 0.8.
A resin composition comprising a base resin of at least one selected from the group consisting of an ethylene / α-olefin copolymer and an ethylene / vinyl acetate copolymer having a weight of 90 g / cm ^3. The cable according to 1 or 2.