JP3344483B2 - Heat resistant high voltage lead wire for DC - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant DC used for wiring in electronic equipment such as a television, an electromagnetic cooker, a copying machine, and a computer, which has a characteristic satisfying a UL standard having a temperature rating of 125 ° C. or more. The present invention relates to a high-voltage lead wire.

[0002]

2. Description of the Related Art Insulated wires used for wiring in electronic devices such as televisions, electromagnetic cookers, copiers, and computer devices are important for safety against fire, and are regulated by the Electrical Appliance and Material Control Law in Japan and the UL standard in the United States. In Canada, flame-retardant insulated wires that have been certified according to CSA standards are used. further,
Since the flame-retardant insulated wires used in the high-voltage parts of the wiring in electronic equipment handle high DC voltages of 10 to 40 kV, safety against withstand voltage is also important.

Conventionally, in order to satisfy both flame retardant and withstand voltage performance, polyethylene having good electric performance is used as an inner layer,
An electric wire having a shared function is used as a two-layer structure including an outer layer of a highly flame-retardant composition coated thereon. For example, the conductor is coated with polyethylene with a melting point of 105 ° C or higher, and the outer layer is made of a polymer containing ethylene, vinyl acetate, and vinyl chloride as the main repeating unit in order to obtain flame retardancy as a whole wire. An electric wire coated with a resin composition is known (see Japanese Patent Publication No. 52-41786). Examples of the flame-retardant jacket include chlorinated polyethylene-vinyl chloride graft copolymer (see Japanese Patent Publication No. 54-15058) and chlorosulfonated polyethylene-vinyl chloride graft copolymer (JP-A-49-42755). Is also known. Such an insulated wire as a whole wire by making use of the excellent electrical insulation and tracking resistance of polyethylene, and supplementing the flammability, which is a disadvantage of polyethylene, with a flame-retardant resin composition provided on the outer periphery. This ensures the flame retardancy.

[0004] As an example of a single-layer structure, an insulated wire in which a conductor is coated with a resin composition containing a flame-retardant resin as a main component, such as chlorinated polyethylene, is also used as a high-voltage wire. . Further, a method is known in which a flame retardant is added to polyethylene to make the polyethylene itself flame-retardant.

On the other hand, the use environment is becoming more and more severe. Since the miniaturization of equipment has been advanced and the functions are required to be multi-functional, the amount of wiring has increased due to many parts set in narrow places, etc., and more safety is required for wiring materials, High heat resistance is required. It is conceivable to meet such a demand by using a high heat-resistant resin other than polyolefin. Generally, an insulated wire having a conductor coated with a vulcanized silicone resin is used as a high-voltage wire used for applications requiring a heat resistance temperature of 150 ° C. or higher. Also, a DC high-voltage electric wire using a fluorine-based resin such as ethylene tetrafluoride or propylene hexafluoride as an insulator is known.

[0006]

[Problems to be Solved by the Invention] However, Japanese Patent Publication No. 52-417
The insulated wires disclosed in JP-B-86, JP-B-54-15058, and JP-A-49-42755 are flame-retardant mainly composed of a polymer containing a monomer containing vinyl chloride or halogen as a repeating unit. Since the electric wire is coated with the resin composition, the upper limit of the heat resistance temperature of the electric wire is 105 ° C., which cannot meet the demand for higher heat resistance. Insulated wires in which a conductor is coated with a resin composition having a single-layer structure also have a heat resistance of an upper limit of 105 ° C., and cannot meet the demand for high heat resistance. Further, the method of flame retarding polyethylene itself to which a flame retardant is added generally has a problem that heat resistance and withstand voltage characteristics deteriorate, and a good high-voltage lead wire has not been obtained.

On the other hand, an insulated wire coated with a silicone resin vulcanizate has excellent flexibility and electrical characteristics, but the silicone resin vulcanizate is inherently easily torn.
The coating layer may be damaged during terminal processing or wiring routing,
In a remarkable case, processing problems such as cracks in the coating layer often occur. As a means for solving these problems, a method of protecting a silicone resin by covering a silicone insulated wire with a glass braided tube or a resin tube is generally known. However, generally, there is a problem that a silicone insulated wire is expensive. Also,
In addition to the price of the electric wire itself, processing costs for covering the protective tube are required, and mounting the protective tube also causes mounting problems such as an increase in the overall outer diameter. On the other hand, electric wires using fluorine resin as an insulator
Although it is an excellent wire having heat resistance of 150 ° C or more, its price is higher than silicone-based insulated wire, and it is not practical except for special applications.

An object of the present invention is to provide a DC high-voltage lead wire rated at 125 ° C. that can be efficiently manufactured with inexpensive materials.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has intensively studied a polyolefin resin composition, and the insulating coating on the conductor is formed of the polyolefin resin composition. Vertical flame retardancy (VW-
A high-voltage lead wire for direct current having the characteristics of 1) and having a temperature rating of 125 ° C. or higher was obtained.

The following are specific examples of polyolefin resin compositions having the above-mentioned UL standard vertical flame retardancy (VW-1) and satisfying the characteristics of a temperature rating of 125 ° C. or higher. With respect to 100 parts by weight of polyolefin resin, 100 parts by weight or more and 200 parts by weight or less of untreated metal hydroxide and 5 parts by weight or more and 50 parts by weight or less of a halogen-based flame retardant are mixed by the following general formula. A polyolefin resin composition in which the indicated organosilicon compound is added and mixed at a ratio of 1 part by weight or more and 10 parts by weight or less.

[0011]

Embedded image

Further, the present invention is a DC high voltage lead wire obtained by coating the above resin composition on a conductor and irradiating the coating with ionizing radiation.

Examples of the polyolefin resin include, in addition to polyethylene, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, ethylene-1-butene copolymer, ethylene -1-hexene copolymers and ethylene α-olefin copolymers such as ethylene propylene rubber. In particular, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer and ethylene ethyl acrylate copolymer can be preferably used from the viewpoint of flexibility and extrudability in the case of forming a resin composition.

Examples of the halogen-based flame retardant include chlorine-based flame retardants such as perchloropentacyclodecane, and brominated flame retardants such as brominated diphenyl ether derivatives, brominated bisphenol derivatives, brominated epoxy resin derivatives, and brominated phthalimide derivatives. Examples thereof include a flame retardant, a phosphorus-containing brominated flame retardant such as brominated phosphate, and trichloroethyl phosphate. It is also possible to enhance the flame retardant effect by using a flame retardant auxiliary such as antimony trioxide, borates or molybdenum oxide in combination. The halogen-based flame retardant is preferably set in the range of 5 to 50 parts by weight, particularly from the viewpoint of vertical flammability (VW-1) of a DC high-voltage electric wire having an insulation coating thickness exceeding 1.0 mm, and less than 5 parts by weight. Flame retardancy is insufficient, and if it exceeds 50 parts by weight, heat aging resistance is adversely affected.

Examples of the metal oxide include aluminum hydroxide, magnesium hydroxide, calcium hydroxide and the like.
Magnesium hydroxide in the range of 0.1 to 3 μm is preferred, and those not surface-treated with fatty acid salts, silane couplings and the like are preferred from the viewpoint of high-pressure cut-through characteristics and initial breaking tensile strength. The addition amount of the metal oxide is preferably set in the range of 100 to 200 parts by weight from the viewpoint of the high-pressure cut-through property.If the amount is less than 100 parts by weight, the high-pressure cut-through property is insufficient. Adversely affect

The organosilicon compounds represented by the aforementioned general formula include γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyldimethoxymethylsilane, γ-methacryloxyethyltrimethoxysilane. Methoxysilane and the like can be exemplified. The organosilicon compound is preferably used as a surface treatment agent, and is preferably added and kneaded during hot melt kneading of the polyolefin, the halogen-based flame retardant, and the metal hydroxide. The addition amount of the organosilicon compound is preferably from 1 to 10 parts by weight in the range of 1 to 10 parts by weight in terms of the balance between high-pressure cut-through characteristics and initial breaking tensile strength when the addition amount of the metal hydroxide is in the range of 100 to 200 parts by weight. with insufficient pressure cut-through characteristic is less than, if the initial fracture strength also 1.06 kg / mm ² is UL standard value of polyolefin insulated wire a measure of acceptance below this value, exceeds 10 parts by weight flame retardant Adversely affect

Various additives can be appropriately added to the above resin composition as required. For example, talc, clay,
Inorganic fillers such as calcium carbonate, magnesium carbonate, and zinc oxide; flame retardant aids such as antimony trioxide; pentaerythrityltetrakis [3- (3,5-di-tert-butyl-4);
-Hydroxyphenyl) propionate]. Antioxidants such as stearylthiodipropionate, lubricants such as zinc stearate, coloring agents, and polyfunctional monomers such as trimethylolpropane trimethacrylate to promote crosslinking. Can be

The above resin composition can be mixed by a known mixing device such as a Banbury mixer, a pressure kneader, an open roll mixer, a single-shaft or twin-shaft mixer. Further, the resin composition can be coated on the conductor by an existing melt extruder, and the conductor may be coated with a single layer or a similar material in multiple layers.

For the crosslinking of the resin composition, heat vulcanization is possible by using a method in which an organic peroxide is previously added to the resin mixture and then heated with pressurized steam after molding. From the viewpoint of balance between high-pressure cut-through characteristics and mechanical properties such as tensile strength and elongation of the coating layer, crosslinking by irradiation with ionizing radiation is preferred. Examples of the ionizing radiation include an α-ray, an electron beam (β-ray), a γ-ray, an X-ray, an ultraviolet ray, and the like, and an electron beam is particularly preferable from the viewpoint of industrial use such as transmission thickness, irradiation dose, and irradiation time.

Note that the temperature rating of 125 ° C. means that the test passes at a test temperature of 125 ° C. in a high-pressure cut-through test of the UL standard, and that the heat aging resistance satisfies the standard of 125 ° C. With heat aging resistance, in the case of polyolefin insulated wire, the UL standard of 125 ° C has a sample with a residual tensile strength of at least 70%, a residual elongation of 65% or more after a heat aging test at 158 ° C for 7 days, and a residual elongation of 65% or more. After the heat aging test at 136 ° C. for 60 days, it is specified that the residual ratio of the tensile strength at break is 70% or more and the residual elongation ratio is 65% or more. In addition, 150 ℃ of UL standard
In the rating, the residual ratio of the tensile strength at break of the sample after the heat aging test at 180 ° C for 7 days is 70% or more, the residual elongation is 65% or more, and
It is specified that the residual ratio of the tensile strength at break of the sample after the heat aging test at 60 ° C. is 70% or more and the residual elongation is 65% or more.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. The heat-resistant high-voltage direct current lead wire of the present invention is formed by irradiating an insulating coating on a conductor with a polyolefin resin composition by ionizing radiation. The polyolefin resin composition, 100 parts by weight of polyolefin resin, 100 parts of metal hydroxide without surface treatment
When mixing at least 5 parts by weight and not more than 50 parts by weight of the halogen-based flame retardant, the organosilicon compound represented by the above general formula was added and mixed at a ratio of 1 part by weight or more and 10 parts by weight or less. Use things. Here, FIG.
(B) is a cross-sectional view of a specific example of the DC high-voltage electric wire of the present invention, wherein 1 is a conductor, and 2 and 3 are coating layers made of the resin composition. The coating layers 2 and 3 may be of the same composition or of different types within the range of the resin composition.

According to the present invention, the above polyolefin resin composition is considered to be technically difficult among the evaluation methods described in Subject 758 of UL standard, which is known as a method for evaluating high-voltage electric wires of electronic equipment. It was found from the following test examples that it can pass the cut-through test and (2) the flame retardancy test.

FIG. 2 is an explanatory diagram of a high-pressure cut-through test according to UL Standard Subject758. As shown in the drawing, two parallel-arranged ones were set in a chamber set at the rated temperature.
When a 1 pound load 10 is applied to both ends of the electric wire 13 through a / 32 ″ diameter drill rod 11 and a voltage 1.5 times the rated voltage is applied from the DC power supply 12, dielectric breakdown may occur within 7 hours. Fig. 3 is an explanatory view of the flame retardant test according to the UL standard, as shown in Fig. 3. As shown in the drawing, an electric wire 18 set up vertically in a chamber 14 provided to prevent the movement of ambient air. The fire was extinguished within 60 seconds when the flame was applied from the bottom with the gas burner 15, and the cotton wool 17 at the bottom must not burn due to the drop of burning material, and the kraft paper 16 at the top burned or burned with the flame. This is a must-have test.

[0024]

[Test Example] An electric wire sample was prepared by the following method. Using an open roll mixer heated to 130 ° C. the resin compositions shown in Tables 1-3, polyolefin resin, fillers,
An organosilicon compound, an antioxidant, etc. are simultaneously added and kneaded, and then pelletized.
Extrusion coated on 8mmφ soft copper conductor, outer diameter 2.27mmφ and 4.2
After forming an insulated wire of 3 mmφ, an electron beam at an acceleration voltage of 2 MV was irradiated to obtain a test sample.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

In the resin compositions of Tables 1 to 3, 10 parts by weight of antimony trioxide and 10 parts by weight of pentaerythrityltetrakis [3- (3,5-di- [t-butyl-4-hydroxyphenyl) propionate], 1 part by weight of distearylthiodipropionate, and 0.5 part by weight of zinc stearate. Antimony trioxide is a flame retardant aid, pentaerythrityltetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] .distearylthiodipropionate is an antioxidant, zinc stearate. Is a lubricant.

In Tables 1 to 3, the high pressure cut-through test
Apply a 1 lb load to both ends of the wire sample in a 5 ° C gear oven, apply 15 kV DC to 2.27 mmφ sample, apply 60 kV DC to 4.23 mmφ sample, test at n = 3 and insulate The breaking time was measured, and those holding all three points for 8 hours or more were judged to be acceptable.

In the heat aging test, as an example, an electric wire sample of 2.27 mmφ was evaluated for the breaking tensile strength and the residual ratio of elongation of a sample heat-aged in a gear oven at 158 ° C. for 7 days and a sample heat-aged at 136 ° C. for 60 days. . Here, the residual ratio (%) = (value of heat-aged sample / initial value) × 100, and the residual tensile strength at break is 70% or more;
A residual growth rate of 65% or more was used as a measure of pass / fail. Burn test is VW-
According to No. 1, n = 5.

Composition of resin coating layer and high pressure cut-through test
The characteristics of the test, heat aging test and combustion test are as follows.
You. Examples 1 to 7 are based on 100 parts by weight of polyolefin resin.
100% untreated magnesium hydroxide
~ 200 parts by weight, halogenated flame retardant is 10 ~ 50
An organosilicon compound in the range of parts by weight and of the general formula
Extrusion coating of resin composition with 1 to 10 parts by weight on conductor
And cross-linked by electron beam irradiation.
Passed through test, and fire test 2.27φ and 4.23φ both
Has passed. Initial breaking tensile strength is also 1.1-1.3kg / mm²Range of
1.06kg / mm required by UL standard²More than
Addition, passed 158 ℃ 7 days and 136 ℃ 60 days heat aging test
You can see that it is doing. In addition, these samples are insulated
Young's modulus is about 3-6kg / mm ²And flexibility
Is also an excellent material.

In Comparative Example 1, 200 parts by weight of magnesium hydroxide without surface treatment, 20 parts by weight of a halogen-based flame retardant,
The sample was 5 parts by weight of the organosilicon compound of the general formula, and was not crosslinked by electron beam irradiation. The sample failed the high-pressure cut-through test, and the initial breaking tensile strength was below the UL standard value of 1.06 kg / mm ² . In addition, the results of the combustion test also failed for both 2.27φ and 4.23φ.

In Comparative Example 2, a resin composition to which an organosilicon compound of the general formula was not added was used for insulating coating, and did not pass the high-pressure cut-through test.

Comparative Example 3 used magnesium hydroxide surface-treated in advance with oleate, and passed the combustion test, but had low initial tensile strength at break and failed the high-pressure cut-through test. The decrease in residual elongation after the heat aging test is remarkable.

Comparative Example 4 used magnesium hydroxide which had been surface-treated with vinylsilane in advance, and passed the combustion test, but had a low initial tensile strength at break, failed the high-pressure cut-through test, and exhibited heat aging. The residual elongation after the test is significantly reduced.

Comparative Example 5 used magnesium hydroxide which had been surface-treated with γ-methacryloxypropyltrimethoxysilane in advance, and passed the combustion test, but had an initial breaking tensile strength of less than 1.06 kg / mm ² . It did not pass the high-pressure cut-through test, and the residual elongation after the heat aging test was less than 65%.

In Comparative Example 6, vinyl triethoxysilane was used in place of the organosilicon compound of the general formula. However, it did not pass the high-pressure cut-through test and the initial tensile strength at break did not satisfy 1.06 kg / mm ² . .

Comparative Example 7 was prepared by adding trimethylolpropane trimethacrylate, a polyfunctional monomer often used as a crosslinking accelerator for thermoplastic resins such as polyolefin resins, to promote crosslinking during electron beam irradiation. However, it did not pass the high pressure cut-through test,
Sample failed in the combustion test.

Comparative Example 8 is a sample containing 80 parts by weight of magnesium hydroxide without surface treatment, and does not pass the high-pressure cut-through test.

Comparative Example 9 was a sample containing 240 parts by weight of magnesium hydroxide and passed the high-pressure cut-through test. However, the extrusion appearance was slightly poor, the initial elongation was less than 100%, and there was a problem in practical use. .

Comparative Example 10 is a sample to which no halogen-based flame retardant was added, and passed the high-pressure cut-through test. In the VW-1 test, a sample of 2.27φ passes, but a sample of 4.23φ fails.

Comparative Examples 11 and 12 used phosphorus-based flame retardants such as tributyl phosphate and ammonium polyphosphate without using a halogen-based flame retardant. It can be seen that the high-pressure cut-through characteristic was adversely affected.

In Comparative Examples 13 and 14, a resin composition obtained by adding 2 parts by weight of dicumyl peroxide as an organic peroxide to 100 parts by weight of a polyolefin resin was extrusion-coated on a conductor, and then heated and heated with pressurized steam. This is a sample that has been sulfurized. Comparative Example 14, which satisfies the high-pressure cut-through property, has an initial elongation of 100
%, And the sample of Comparative Example 13 has no problem with the initial elongation property, but has a problem with the high-pressure cut-through property and the heat aging property, so that the properties cannot be balanced.

As described above, for 100 parts by weight of a polyolefin resin such as EVA resin or EEA resin, 100 parts by weight or more and 200 parts by weight or less of magnesium hydroxide without surface treatment, and 5 parts by weight of a halogen-based flame retardant are used. Not less than 50 parts by weight, and a resin composition prepared by adding and mixing the organosilicon compound represented by the general formula at a ratio of 1 part by weight or more and 10 parts by weight or less, and coating this on a conductor, By irradiating with ionizing radiation, in other words, in the method for producing a resin composition, an organosilicon compound represented by the general formula and a polyolefin resin, magnesium hydroxide without surface treatment, fillers such as halogen-based flame retardants The high-pressure cut-through property and flame retardancy are obtained only by irradiating ionizing radiation such as an electron beam using a kneaded composition added during hot melt kneading. (VW-1), a DC high-voltage lead wire having 125 ° C grade or higher heat aging resistance and excellent flexibility can be obtained.

[0045]

As described above, according to the DC high-voltage electric wire of the present invention, a DC high-voltage electric wire rated at 125 ° C. can be efficiently manufactured with inexpensive materials, and the heat resistance in the field of DC high-voltage electric wires can be improved. Some of them can respond to requests and have a very large utility value.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views of a specific example of a DC high-voltage electric wire according to the present invention.

FIG. 2 is an explanatory diagram of a high-pressure cut-through test.

FIG. 3 is an explanatory diagram of a VW-1 combustion test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor 2 Coating layer by resin composition in this invention

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 23/00 H01B 7/34 A

Claims (1)

(57) [Claims] An insulating coating on a conductor is formed of a polyolefin resin composition, wherein the polyolefin resin composition is a polyolefin resin.
More than 100 parts by weight of metal hydroxide without surface treatment
A resin composition in which a halogen-based flame retardant is added in an amount of from 5 parts by weight to 50 parts by weight, and an organosilicon compound represented by the following general formula is added and mixed in a proportion of from 1 part by weight to 10 parts by weight. The insulating coating is irradiated with ionizing radiation, and the insulating coating is a UL (Under Writers Laboratries)
A heat-resistant high-voltage direct current lead wire having a standard vertical flame retardancy (VW-1) and a characteristic of a temperature rating of 125 ° C or higher. Embedded image