CN101186728A - Arc-extinguishing resin molded product and circuit breaker using same - Google Patents

Description

Arc-extinguishing resin molded product and circuit breaker using same

technical field

The present invention relates to an arc extinguishing resin molded article having flame retardant properties for eliminating arcs generated from contact pieces when current is interrupted in a circuit breaker or the like, and to molding using such an arc extinguishing resin product breakers.

Background of the invention

When the contact pieces are opened by passing an overcurrent or a rated current therethrough, an arc is generated between the contact pieces of the movable contact part and the fixed contact part of the circuit breaker. In order to extinguish the arc, there is generally an arc extinguishing device on the circuit breaker, and the device has an arc extinguishing chamber formed by arc extinguishing components around the position where the arc is generated. The arc-quenching component can be thermally decomposed by the arc, and the thermally decomposed gas produced by this arc-quenching component extinguishes the arc.

The matrix resins of arc extinguishing parts initially used include thermosetting resins such as unsaturated polyester resins (Patent Document 1) and melamine resins (Patent Document 2), thermoplastic resins such as polyolefin resins, polyamide resins, and polyacetal resins (Patent Document 3).

However, thermosetting resins have a problem that their molding properties are inferior to those of thermoplastic resins because mold flash easily occurs during molding. During the arc extinguishing process, the pyrolysis gases generated by the arc extinguishing components increase the pressure in the arc extinguishing device. The thermosetting resin has poor compressive strength, is easy to break, and has relatively high hardness, so it is difficult to miniaturize the arc extinguishing device.

On the other hand, thermoplastic resins hardly cause mold flash, but are poor in strength, pressure resistance, and heat resistance, so such arc-extinguishing parts tend to be deformed or deteriorate over time. Thermoplastic resins containing a large number of aromatic rings, such as aramid resins, have excellent strength, pressure resistance and heat resistance, but such resins tend to release free carbon during combustion. As a result, the arc extinguishing device may be contaminated by these free carbons, and its electrical insulation property may be lowered.

In order to improve the strength, pressure resistance and heat resistance of thermoplastic resins and thermosetting resins, attempts have been made to include inorganic fillers such as reinforcing fibers in the resins (Patent Documents 1 to 4). However, increasing the content of the inorganic filler reduces the amount of pyrolysis gas generated, leading to a problem of poor arc extinguishing performance.

Patent Document 5 discloses a circuit breaker using a resin molded product obtained by subjecting thermoplastic resins such as polyester and polyamide to electron irradiation.

Recently, there has been an increasing demand for the flame retardancy level of resin materials used in circuit breakers. In order to meet this requirement, it is conceivable to use a flame retardant resin for the matrix resin of the arc extinguishing material. Compounds containing halogens such as bromine are known to achieve effective flame-retardant properties in resins, and resins containing additives of halogen compounds have been used as flame-retardant resins for general purposes. However, flame retardant resins containing a large amount of halogen compounds may generate dioxins under certain combustion conditions. From the viewpoint of environmental protection, the use of non-halogen flame-retardant resins that do not contain halogen compounds has been demanded in recent years.

[Patent Document 1]

Japanese Patent No.3098042 and its foreign counterparts: US Patent 6,046,258, German Patent DE 69717433 and European Patent EP 089 7955

[Patent Document 2]

Japanese Unexamined Patent Application Publication No.H02-256110

[Patent Document 3]

Japanese Unexamined Patent Application Publication No.H07-302535 and its foreign counterparts: US Patent 5,841,088, European Patent Application Publication No.0 694 940, and Chinese Patent Application Publication No.CN 1124 402

[Patent Document 4]

Japanese Unexamined Patent Application Publication No.H08-171847, and its foreign counterparts: US Patent No. 6,361,848, German Patent DE 69532063, European Patent EP 071 8356, and Chinese Patent CN 1 169 866

[Patent Document 5]

International patent application publication WO 2003-044818, and its foreign counterparts: European patent application publication EP 1 475 817 and Chinese patent CN 1 255 839

Contents of the invention

Problems solved by the present invention

By subjecting thermoplastic resins to cross-linking treatment, although some improvements in strength, heat resistance and pressure resistance can be observed, arc extinguishing properties are not improved. In addition, it is difficult to suppress the pressure rise in the arc extinguishing device due to pyrolysis gas generated during arc extinguishing, and the arc extinguishing device is easily broken due to the pressure rise during arc extinguishing. In addition, flame retardancy has also been an unresolved issue.

Accordingly, it is an object of the present invention to provide an arc-extinguishing resin molded product which generates pyrolysis gas at a slightly elevated pressure and which can efficiently extinguish an arc generated at the time of disconnection, which has the Heat resistance to elevated temperature and pressure resistance to elevated pressure, and good flame retardancy. Another object of the present invention is to provide a circuit breaker using such an arc-extinguishing resin molded article.

way to solve the problem

To achieve the above objects, the arc extinguishing resin molded article of the present invention comprises a resin composition containing a polyolefin resin (A) in which a part of hydrogen atoms in a methylene chain is substituted by a hydroxyl group , the content of the hydroxyl group is in the range of 0.2-0.7 mol relative to 1 mol of methylene, the resin composition also includes a reactive organophosphorus flame retardant (B), the flame retardant has unsaturated terminal bonds, and the resin molded product Irradiation is performed after shaping to effect crosslinking.

In the above-mentioned arc-extinguishing resin molded product of the present invention, through the chemical reaction between the unsaturated terminal bond of the reactive organophosphorus flame retardant (B) and the polyolefin resin (A) under the assistance of irradiation, the formation of Cross-linking of three-dimensional network structures. As a result, the flame retardant component is stably incorporated in the resin. Therefore, the flame retardant hardly breeds out and can maintain flame-retardant properties for a long period of time. Strength, heat resistance, and pressure resistance are also improved due to crosslinking that forms a three-dimensional network structure in the polyolefin resin (A).

The polyolefin resin (A) has OH groups in its side chains, which are easily dissociated by pyrolysis, generating pyrolysis gas containing high concentrations of hydrogen, _H2O , _O2 , and O, and thus capable of extinguishing arcs immediately. The polyolefin resin (A) contains a low concentration of a component, such as tar, which contributes little to the arc extinguishing function but controls the pressure rise in the arc extinguishing device. In addition, carbon hardly adheres to components of the arc extinguishing device during the arc extinguishing process. Thus, electrical insulation in the arc extinguishing device is guaranteed.

The resin composition of the arc-extinguishing resin molded article of the present invention preferably contains the polyacetal resin (C) in an amount ranging from 5 to 90 parts by weight relative to 100 parts by weight of the polyolefin resin (A). The polyacetal resin (C) contains 75-100 mol% of repeating units derived from formaldehyde. Although polyacetal resins generally generate pyrolysis gas with high arc extinguishing properties, it has been found difficult to mold them by melt kneading, ie, poor in moldability. Because the polyacetal resin produces a large amount of pyrolysis gas, which will cause a relatively large increase in pressure, which will easily increase the pressure in the arc extinguishing device. However, in this aspect of the present invention, the polyolefin resin (A) is used in combination with the polyacetal resin (C), thereby improving the arc extinguishing performance without impairing the molding performance of the resin composition.

The resin composition of the arc-extinguishing resin molded article of the present invention preferably contains 1-70% by weight of one or more types of inorganic fillers (D) selected from the group consisting of glass fibers, barium titanate whiskers, silica gel particles , boehmite, talc, magnesium carbonate and metal hydroxides. By this aspect of the invention, the strength and pressure resistance of the resin molded article are improved.

The polyolefin resin (A) in the arc-extinguishing resin molded article of the present invention preferably has a latent heat of decomposition of at least 30 cal/g.

The polyolefin resin (A) in the arc extinguishing resin molded article of the present invention is preferably an ethylene-vinyl alcohol copolymer.

Through these aspects of the present invention, pyrolysis gas excellent in arc extinguishing property is generated, so that arc can be extinguished immediately. Therefore, the arc voltage is maintained.

Preferably in the arc-extinguishing resin molded article of the present invention, the reactive organic phosphorus flame retardant (B) is an organic phosphorus compound represented by the following chemical formula (I) and/or chemical formula (II), and the resin composition The content of the flame retardant is in the range of 0.5-20% by weight.

In the formula, R ¹ to R ⁴ each represent CH ₂ =CY ¹ -Y ² -, or a heteroatom-containing monofunctional aromatic hydrocarbon group, and R ⁵ represents a heteroatom-containing bifunctional aromatic hydrocarbon group;

X ¹ to X ⁴ each represent a group selected from the group consisting of -O-, -NH-, -(CH ₂ =CY ¹ -Y ² )N-, and at least one of the groups in X ¹ to X ⁴ contains -NH -or-(CH ₂ =CY ¹ -Y ² )N-;

At least one of R ¹ to R ⁴ and X ¹ to X ⁴ contains CH ₂ =CY ¹ -Y ² -;

^Y represents a hydrogen atom or a methyl group; and

Y ² represents an alkylene group having 1-5 carbons or -COO-Y ³ -, wherein Y ³ represents an alkylene group having 1-5 carbons.

In the formula, at least one P-C bond is included in one molecule;

Ar ¹ and Ar ² each represent a difunctional aromatic hydrocarbon group with a maximum carbon number of 20 and no mobile hydrogen, and n is an integer of 0, 1 or 2; R ⁶ to R ¹⁰ each represent a group selected from the group consisting of: -NHCH ₂ CH=CH ₂ , -N(CH ₂ CH=CH ₂ ) ₂ , -OCH ₂ CH=CH ₂ , -CH ₂ CH=CH ₂ , -CH ₂ CH ₂ OCH=CH ₂ , -(C ₆ H ₄ )-CH=CH ₂ , -O(C ₆ H ₄ )-CH=CH ₂ , -CH ₂ (C ₆ H ₄ )-CH=CH ₂ , -NH(C ₆ H ₄ )-CH=CH ₂ , -N(CH ₂ CH=CH ₂ )-(C ₆ H ₄ )-CH=CH ₂ , -OR-OOC-C(R')=CH ₂ , -NH-R-NHCO-C(R')= CH ₂ and an aryl group with a maximum carbon number of 12, wherein R represents an alkylene group with a carbon number of 2-5, and R' represents a hydrogen atom or a methyl group;

At least one group among R ⁶ to R ¹⁰ contains a -CH=CH ₂ group or a -C(CH ₃ )=CH ₂ group.

The reactive organophosphorus flame retardant (B) is stable in its energy state, hardly evaporates during kneading and molding of the resin, and furthermore, hardly decomposes due to heat and shear. Therefore, there is no adverse effect on molding properties.

The polyacetal resin (C) in the arc extinguishing resin molded article of the present invention is preferably an oxyethylene copolymer or an oxyethylene polymer. By this aspect of the present invention, pyrolysis gas excellent in arc extinguishing property is generated, so that arc can be extinguished immediately. Therefore, the arc voltage is maintained.

In the arc-extinguishing resin molded article of the present invention, the polyacetal resin (C) is preferably dispersed in the polyolefin resin (A) to form a microphase-separated structure. With this aspect of the invention, the polyacetal resin (C) is easily pyrolyzed during the thermal decomposition of the arc-extinguishing resin molded article, and emits pyrolysis gas having high arc-extinguishing performance. Therefore, the arc can be extinguished immediately.

The circuit breaker of the present invention includes a fixed contact portion having a fixed contact piece; a movable contact portion having a movable contact piece to reach contact with the fixed contact portion and guide closing and opening actions with the fixed contact portion; and An arc device for extinguishing an arc generated during opening and closing actions between a fixed contact portion and a movable contact portion; wherein the arc extinguishing device includes a unique arc extinguishing resin molded product different from the previous ones. In the circuit breaker according to the invention, it is possible to effectively extinguish the arc generated between the contact pieces during the current interruption and to control the pressure rise in the arc extinguishing device. Therefore, this circuit breaker is compact and has excellent performance during circuit breaking, including overload breaking and short circuit breaking.

Invention effect

The arc extinguishing resin molded article of the present invention has satisfactory strength, pressure resistance, heat resistance, flame retardancy and molding properties. In addition, the resin molded product can release pyrolysis gas with high arc extinguishing performance. As a result, the arc formed between the contact pieces when the current is interrupted can be effectively extinguished, and the pressure in the arc extinguishing device can be kept at a low level. The circuit breaker using the arc-extinguishing resin molded article of the present invention can be miniaturized and has excellent circuit breaking performance including overload breaking and short circuit breaking.

Brief description of the drawings

Figure 1 is a perspective view of an embodiment of the circuit breaker of the present invention, showing a partial section;

Fig. 2 is the perspective view of the arc extinguishing chamber used in the circuit breaker of the present invention;

Fig. 3 is a sectional view of an arc extinguishing device used in the circuit breaker of the present invention.

Explanation of reference signs

1: Movable contact part

2: grid

4: Power side

5: fixed contact part

Detailed ways

The arc extinguishing resin molded article of the present invention comprises a resin composition comprising a polyolefin resin (A) in which a part of hydrogen atoms in a methylene chain is substituted with a hydroxyl group (-OH) The content of the hydroxyl group is in the range of 0.2-0.7 mol relative to 1 mol of methylene (-CH ₂ -), and the resin composition further includes a reactive organophosphorus flame retardant (B) having an unsaturated terminal bond. The resin molded article is subjected to radiation crosslinking treatment after molding.

The hydroxyl group content of the polyolefin resin (A) is in the range of 0.2-0.7 mol, more preferably 0.2-0.65 mol, relative to 1 mol of methylene. If the hydroxyl group content in the above-defined portion is less than 0.2, it is difficult to generate pyrolysis gas with good arc extinguishing properties during the pyrolysis process, and as a result, the arc cannot be extinguished immediately. In addition, the stress of the arc extinguishing device becomes higher during the arc extinguishing process. At the same time, the arc extinguishing device is contaminated by increased free carbon. Then the electrical insulation of the arc extinguishing device is reduced. If the hydroxyl group content of the polyolefin resin (A) exceeds 0.7 mol, the intermolecular hydrogen bond strength is greater than the case where the hydroxyl group content is less than or equal to 0.7 mol. The stronger the hydrogen bond, the closer the melting point of the polyolefin resin (A) is to the degradation temperature. Then, the molding process becomes difficult due to thermal decomposition during melt-kneading.

The polyolefin resin (A) has a latent heat of decomposition of preferably at least 30 cal/g, more preferably at least 40 cal/g. The latent heat of decomposition of the polyolefin resin (A) can be increased by increasing the hydroxyl group content in the resin. The latent heat of decomposition of the polyolefin resin in which a part of the hydrogen atoms in the methylene chain is substituted by hydroxyl groups and the content of the hydroxyl groups is in the range of 0.2-0.7 mol relative to 1 mol of methylene is in the range of 30-50 cal/g. The latent heat of decomposition of a resin can be measured by heating and decomposing a sample resin in an inert atmosphere.

A preferred polyolefin resin is ethylene vinyl alcohol copolymer, which is particularly advantageous because of its excellent arc extinguishing properties. Whereas polyethylene exhibits poor arc extinguishing properties, poly(vinyl alcohol) can use conditional molding.

The reactive organophosphorus flame retardant (B) is an organophosphorus compound having an unsaturated terminal bond, preferably a compound represented by the following chemical formula (I) or chemical formula (II).

In the formula, R ¹ to R ⁴ each represent CH ₂ =CY ¹ -Y ² -, or a heteroatom-containing monofunctional aromatic hydrocarbon group, and R ⁵ represents a heteroatom-containing bifunctional aromatic hydrocarbon group;

X ¹ to X ⁴ each represent a group selected from the group consisting of -O-, -NH-, -(CH ₂ =CY ¹ -Y ² )N-, and at least one of the groups in X ¹ to X ⁴ contains -NH -or-(CH ₂ =CY ¹ -Y ² )N-;

At least one of R ¹ to R ⁴ and X ¹ to X ⁴ contains CH ₂ =CY ¹ -Y ² -;

^Y represents a hydrogen atom or a methyl group; and

Y ² represents an alkylene group having 1-5 carbons or -COO-Y ³ -, wherein Y ³ represents an alkylene group having 1-5 carbons.

In the formula, at least one P-C bond is included in one molecule;

Ar ¹ and Ar ² each represent a difunctional aromatic hydrocarbon group with a maximum carbon number of 20 and no mobile hydrogen, and n is an integer of 0, 1 or 2;

R ⁶ to R ¹⁰ each represent a group selected from the group consisting of -NHCH ₂ CH=CH ₂ , -N(CH ₂ CH=CH ₂ ) ₂ , -OCH ₂ CH=CH ₂ , -CH ₂ CH=CH ₂ , -CH ₂ CH ₂ OCH=CH ₂ , -(C ₆ H ₄ )-CH=CH ₂ , -O(C ₆ H ₄ )-CH=CH ₂ , -CH ₂ (C ₆ H ₄ )-CH=CH _2. -NH(C ₆ H ₄ )-CH=CH ₂ , -N(CH ₂ CH=CH ₂ )-(C ₆ H ₄ )-CH=CH ₂ , -OR-OOC-C(R')= CH ₂ , -NH-R-NHCO-C(R')=CH ₂ and an aryl group with a maximum carbon number of 12, wherein R represents an alkylene group with a carbon number of 2-5, and R' represents a hydrogen atom or a methyl group ;

At least one group among R ⁶ to R ¹⁰ contains a -CH=CH ₂ group or a -C(CH ₃ )=CH ₂ group.

The organophosphorus compound contains at least one group of -CH=CH ₂ or -C(CH ₃ )=CH ₂ and is an unsaturated terminal bond. Such functional groups are bonded to the polyolefin resin (A) by irradiating radioactive rays. It is preferable to contain two or more unsaturated terminal bonds in one molecule.

CH ₂ ═CY ¹ -Y ² - in the compound of chemical formula (I) can be, for example, CH ₂ ═CH-CH ₂ -, CH ₂ ═CH-CH ₂ CH ₂ CH ₂ -, CH ₂ ═C(CH ₃ ) _{-CH2- , CH2} =CHCOO- _CH2CH2- , and _CH2 =C( _CH3 ) _COO - _CH2CH2- .

The monofunctional aromatic hydrocarbon group containing a heteroatom in R ¹ to R ⁴ is preferably an aromatic hydrocarbon group having a carbon number of 6-14. Specifically, such groups include -C ₆ H ₅ (phenyl), -C ₆ H ₅ OH (hydroxyphenyl), C ₆ H ₅ -C ₆ H ₅ OH (hydroxybiphenyl), -CH ₂ C ₆ H ₅ (benzyl), -α-C ₁₀ H ₇ (α-naphthyl), and -β-C ₁₀ -H ₇ (β-naphthyl).

The difunctional arene group containing R ₅ heteroatoms is preferably an arene group with a carbon number of 10-14. Specifically, such groups include: -pC ₆ H ₄ -pC ₆ H ₄ -, -pC ₆ H ₄ -CH ₂ -pC ₆ H ₄ -, -pC ₆ H ₄ -C(CH ₃ ) ₃ -pC ₆ H ₄ , -pC ₆ H ₄ -C(=O)-pC ₆ H ₄ -, -pC ₆ H ₄ -SO ₂ -pC ₆ H ₄ - and 2,6-C ₁₀ H ₆ <(2,6 -naphthylene).

The aromatic hydrocarbon groups cited in the specification and claims of the present invention not only include aromatic hydrocarbon groups such as phenyl and -pC ₆ H ₄ -pC ₆ H ₄ -, but also include aromatic hydrocarbon groups containing oxygen or sulfur heteroatoms, Such as hydroxyphenyl and -pC ₆ H ₄ -SO ₂ -pC ₆ H ₄ -.

Specific examples of the organophosphorus compound represented by the chemical formula (I) may be compounds represented by the following structural formulas (I-1) to (I-18).

The compounds shown above can be synthesized using the methods described in WO 2005/012415. For example, the compound of formula (I-1) can be obtained by adding phosphorus oxychloride to dimethylacetamide (DMAc), and adding dissolved 4,4'-biphenyl alcohol and tris ethylamine, react them with each other, and then react with a mixed solution of allylamine and triethylamine.

In the compound represented by the chemical formula (II), specific examples of the aryl group having a carbon number of up to 12 may be -C ₆ H ₅ (phenyl), -C ₆ H ₅ OH (hydroxyphenyl), -C ₆ H ₅ -C ₆ H ₅ OH (hydroxybiphenyl), -α-C ₁₀ H ₇ (α-naphthyl), and -β-C ₁₀ H ₇ (β-naphthyl).

Specific examples of difunctional aromatic hydrocarbon groups with a carbon number up to 20 that do not contain mobile hydrogen in Ar ¹ and Ar ² may be -pC ₆ H ₄ -, -pC ₆ H ₄ -O-, -OpC ₆ H ₄ -O -, -pC ₆ H ₄ -pC ₆ H ₄ -, -pC ₆ H ₄ -CH ₂ -pC ₆ H ₄ -, -pC ₆ H ₄ -C(CH ₃ ) ₂ -pC ₆ H ₄ -, -pC ₆ H ₄ -C(=O)-pC ₆ H ₄ -, -pC ₆ H ₄ -SO ₂ -pC ₆ H ₄ - and 2,6-C ₁₀ H ₆ <(2,6-naphthylene). Mobile hydrogen refers to highly reactive hydrogen contained in functional groups such as OH (hydroxyl group), -NHCO- (amide bond) or -NHCOO- (urethane bond), which is easy to form hydrogen bonds and is easy to bond with metals. Sodium and sodium hydride react at room temperature to produce hydrogen.

Specific examples of the organophosphorus compound represented by formula (II) include compounds represented by structural formula (II-1) to structural formula (II-23). Among these compounds, the compounds of formulas (II-1) to (II-12) are examples where n=0, that is, examples containing two phosphorus atoms in one molecule. Compounds of formulas (II-13) to (II-20) are examples where n=1, ie, examples containing three phosphorus atoms in one molecule. Compounds of formulas (II-21) to (II-23) are examples where n=2 and four phosphorus atoms are contained in one molecule.

The compounds shown above can be synthesized using the methods disclosed in WO 2005-087852. The compound of formula (II-1) can be obtained, for example, by reacting 4,4'-dichlorobiphenyl raw material with phosphorus oxychloride, and then reacting with allyl bromide to introduce an unsaturated group at the end.

The content of the reactive organic phosphorus flame retardant (B) in the resin composition is preferably in the range of 0.5-20% by weight, more preferably in the range of 4-12% by weight. If the content of the reactive organophosphorus flame retardant (B) is less than 0.5% by weight, it is difficult to improve the flame retardant properties, and in addition, because of the low crosslink density of the resin composition, the physical properties of strength, pressure resistance and heat resistance Little has been improved. If the content exceeds 20% by weight, the reactive organophosphorus flame retardant is in excess, so there are unreacted monomers and decomposition gas of the reactive organophosphorus flame retardant, and oligomeric substances may breed out .

The arc extinguishing resin molded article resin composition used in the present invention preferably further contains a polyacetal resin (C).

Although polyacetal resins generally produce pyrolysis gases with high arc extinguishing properties, they were found to be difficult to form in molds by melt kneading, ie, exhibited poor moldability. Because the polyacetal resin produces a large amount of pyrolysis gas, which will cause a relatively large increase in pressure, which will easily increase the pressure in the arc extinguishing device. By using the polyacetal resin in combination with the polyolefin resin (A), the arc extinguishing performance can be improved without impairing the moldability of the resin composition. In addition, it is also possible to suppress the pressure rise of the arc extinguishing device during the arc extinguishing process.

The polyacetal resin (C) contains repeating units derived from formaldehyde in a proportion preferably in the range of 75-100 mol%, more preferably in the range of 80-100 mol%. If the content of the repeating unit is less than 75 mol%, arc extinguishing performance is poor, and rapid arc extinguishing cannot be performed.

A preferred polyacetal resin is oxyethylene copolymer or oxyethylene polymer, these copolymers or polymers are preferred because of their excellent arc extinguishing properties. However, the arc extinguishing performance of metaldehyde is poor.

The content of the polyacetal resin (C) is preferably 5-90 parts by weight, more preferably 7-88 parts by weight, based on 100 parts by weight of the polyolefin resin (A). If the content of the polyacetal resin (C) is less than 5 parts by weight in the ratio defined above, the effect due to the polyacetal resin (C) is expected to be small and the arc extinguishing performance is hardly improved. If the content exceeds 90 parts by weight, the amount of pyrolysis gas increases and the pressure inside the arc extinguishing device rises.

The resin composition used for the arc-extinguishing resin molded article of the present invention contains resins other than the above-mentioned resins; for example, a general-purpose thermoplastic resin may be contained. The content of such a resin is preferably in the range of 0 to 15 parts by weight, more preferably in the range of 0 to 12 parts by weight, relative to 100 parts by weight of the polyolefin resin (A).

The resin composition used for the arc-extinguishing resin molded article of the present invention further contains a radiation crosslinking agent (D). The included radiation cross-linking agent is chemically combined with the resin by irradiating radioactive rays, so that the cross-linked resin has a three-dimensional network structure and increases the cross-linking density. Accordingly, physical properties including strength, heat resistance, and pressure resistance are improved.

Radiation crosslinking agents that can be used include compounds that do not contain aromatic rings and readily generate hydrogen gas, such compounds are difunctional or higher functional melamine compounds with reactive functional groups, including: trimethallyl acrylate, Triallyl acrylate and isocyanato-tri(meth)acrylate. More specifically, the radiation crosslinking agent may be selected from the group consisting of triallyl isocyanurate, trimethallyl isocyanurate, oligomers obtained by free-radical oligomerization of these isocyanurates, Triallyl trimellitate, Trimethallyl trimellitate, Tetraallyl pyromellitate, Tetramethallyl pyromellitate, N, N, N', N', N ", N"-hexaallyl melamine, N, N, N', N', N", N"-hexaallyl melamine, etc.

The content of the radiation crosslinking agent in the resin composition is preferably in the range of 0.5-20% by weight, more preferably in the range of 1-12% by weight. If the content of the radiation crosslinking agent is less than 0.5% by weight, the crosslinking of the resin composition is hardly improved; if the content exceeds 20% by weight, bleeding by the radiation crosslinking agent may occur.

The resin composition used for the arc-extinguishing resin molded article of the present invention preferably contains one or more types of inorganic fillers (D) selected from the group consisting of reinforcing fibers, barium titanate whiskers, silica gel particles, boehmite , talc, magnesium carbonate and metal hydroxides. Containing the inorganic filler improves the dimensional stability as well as the density, pressure resistance and heat resistance of the arc extinguishing resin molded article.

The reinforcing fibers may be selected from, for example, glass fibers, carbon fibers, and metal fibers, among which, glass fibers are preferred because of the strength of glass fibers and adhesiveness to resins and inorganic fillers. A single kind of reinforcing fiber may be used, or two or more types may be used in combination. In addition, fibers can be treated with known surface treatment agents such as silane coupling agents. The glass fibers are preferably surface treated and further covered with resin. This measure also further improves the adhesion to the resin in the resin composition.

The metal hydroxide is preferably dispersed in the polyolefin resin (A) because the resin has the ability to suppress pressure rise. Preferred metal hydroxides include aluminum hydroxide, boehmite and magnesium hydroxide, with a particle size in the range of 1-10 μm.

The content of the inorganic filler (D) in the resin composition is preferably in the range of 1-70% by weight, more preferably in the range of 20-70% by weight. If the content of the inorganic filler (D) is less than 1% by weight, the effect of the inorganic filler can hardly be achieved, and if the content exceeds 70% by weight, the amount of thermally decomposed gas decreases, lowering the arc extinguishing ability.

The resin composition of the arc-extinguishing resin molded article of the present invention may further contain conventional additives other than the above-mentioned substances, as long as these additives do not significantly impair the properties that are the object of the present invention, that is, impair heat resistance , pressure resistance, arc extinguishing ability, strength and flame retardant properties. Additives include, for example, crystallizing nucleus agents, colorants, antioxidants, release agents, plasticizers, heat stabilizers, slip agents, ultraviolet absorbers, and the like.

The arc extinguishing resin molded article of the present invention is produced by irradiating a molded resin composition with radioactive rays.

Molding of the resin composition can be performed by a known method. For example, after the resin composition is melt-kneaded to form pellets, molding is performed by known methods such as injection molding, extrusion molding, vacuum molding, blow molding, and the like. Melt-kneading can be performed using commonly used kneading equipment such as single-screw or twin-screw extruders, Banbury mixers, kneaders, mixing rolls, and the like. The kneading operation is preferably carried out at a temperature in the range of 170-230°C. If the temperature is lower than 170°C, melt-kneading hardly proceeds; if the temperature exceeds 230°C, the hydroxyl groups in the resin composition are dissociated, reducing the arc extinguishing ability. In particular, the following procedure is advantageous in the present invention. The resin composition containing polyolefin resin (A) and polyacetal resin (C) is melt-kneaded and molded at a temperature of 180-220°C in an inert atmosphere, and then cooled to 40-60°C. Through this molding process, a resin molded article with a microphase separation structure can be obtained, wherein the polyacetal resin (C) with a submicron size of 0.1-0.9 μm is formed in the form of islands in the sea, hexagonal columns, or flakes. dispersed in the polyolefin resin (A). By forming a micro-phase separation structure, the polyacetal resin (C) is easily decomposed, and a pyrolysis gas with high arc extinguishing performance is emitted to quickly extinguish the arc. Since crosslinking has not yet started at this stage, the remaining spool portion of the molding process can be recycled.

On the thus obtained resin molded article, radioactive rays are irradiated to obtain the arc extinguishing resin molded article of the present invention. The microphase-separated structure is fixed by the crosslinking effected by this irradiation.

The radiation for irradiating the resin molded article may be α-rays, γ-rays, X-rays, or ultraviolet radiation, among which γ-rays are preferred because γ-rays have strong penetrating properties and can be irradiated uniformly.

The irradiation dose is preferably at least 10 kGy, more preferably in the range of 10-45 kGy. By irradiation of a dose in this range, an arc-extinguishing resin molded article having the above-mentioned excellent properties can be obtained through crosslinking by said irradiation. If the irradiation dose is less than 10 kGy, the three-dimensional network structure formed by cross-linking is not uniform, and unreacted cross-linking agent may bleed. If the dose exceeds 45kGy, the irradiation leaves internal strains due to oxidative decomposition products in the resin molded product which cause distortion and shrinkage

The arc extinguishing resin molded article obtained according to the present invention has excellent strength, pressure resistance, heat resistance, arc extinguishing performance and flame retardancy, and therefore, can be advantageously used as an arc extinguishing device in a circuit breaker.

Next, the circuit breaker of the present invention will be described.

The circuit breaker of the present invention comprises: a fixed contact portion having a fixed contact piece; a movable contact portion having a movable contact piece to come into contact with the fixed contact portion and to perform closing and opening actions with the fixed contact portion; and An arc extinguishing device for extinguishing an arc generated during the opening and closing action between the fixed contact portion and the movable contact portion; wherein the arc extinguishing device includes the arc extinguishing resin molded product described above.

A specific example of such a circuit breaker is shown in FIGS. 1 to 3. FIG. 1 is a perspective view showing a partial section, FIG. 2 is a perspective view of an arc extinguishing device, and FIG. 3 is a sectional view of the circuit breaker.

Referring to Fig. 1, the circuit breaker shown includes a fixed contact part 5 having a monolithic structure, having a power supply side terminal 4 at one end, and a U-shaped bend along the movable contact part 1 at the other end; and a movable contact Part 1, which has a movable contact piece 6 to come into contact with a fixed contact piece 7 on the top end of the U-bend 5a of the fixed contact part. The arcuate corner 9 is connected to the fixed contact part 5 and guides the arc generated between the movable contact piece 6 and the fixed contact piece 7 towards the arc extinguishing means.

The arc extinguishing device is composed of a grid 2 and an arc extinguishing chamber 13 . The grid 2 includes a plurality of plates (five plates in the drawing) stacked on an insulator 12 at predetermined intervals. The movable contact portion 1 makes an opening and closing movement between a closed position marked by a bold line and an open position marked by a dotted line, through a V-shaped notch 2 a formed in the grid 2 . The arc extinguishing chamber 13 is formed of the arc extinguishing resin molded article of the present invention, and is between the movable contact portion 1 and the grid 2 .

The insulator 12 shown in FIGS. 1 and 3 includes a pair of side walls 12a on the left and right sides, and connection members 12b and 12c connecting the side walls at the top and bottom of the walls. The insulator is formed from a single block of melamine molded resin, which is arc resistant. On the opposite faces of the pair of side walls 12a are formed a plurality of grooves 14 of rectangular cross-section, which rise obliquely from the loading side end (right side end in FIG. 3). Each grid piece 2 is press fitted to the groove 14 and forms a bridge between the left and right side walls 12a.

The arc extinguishing chamber 13 includes a pair of left and right side walls 13a, an arcuate front wall 13b connecting the tops of the left and right side walls 13a along the V-shaped notches 2a in the grid 2 . The arc extinguishing chamber 13 also includes a partition wall 15, which separates the arc extinguishing device from the opening-closing device, and an insulating cover 16, which covers the fixed contact part 5. The partition wall and the insulating cover form a single block in the arc extinguishing chamber. . The partition wall 15 has a slit 15a formed along the opening-closing movement path of the movable contact portion. The insulating cover 16 has a window 16a to expose the fixed contact piece 7 . The arc extinguishing chamber 13 is assembled in the insulator 12 from the right side in FIG. The arc extinguishing chamber 13 is supported on the fixed contact portion 5 through the insulating cover 16, and is pressed and fixed by the main body cover (not shown in the figure) of the circuit breaker. In this assembled state, the side walls 13a of the arc extinguishing chamber 13 cover the legs of the grid 2 (parts on both sides of the V-shaped notch), the grid 2 is located on both sides in the movable contact part, and the front wall 13b is located behind the V-shaped notch 2a of the top plate of the grid 2, as shown in FIG.

In the above structure, during current interruption, an arc is formed between the movable contact piece 6 and the fixed contact piece 7, the arc moves into the grid 2, and is extinguished in the grid. Because the two leg parts of the grid 2 are covered from the inside by the two side walls 13a of the arc extinguishing cavity 13, and are shielded from the arc during the current interruption process, these parts of the grid are prevented from melting and scattering due to the arc, and in addition , pyrolysis gas is generated and emitted from the side wall 13a in the vicinity of the arc to promote arc cooling to rapidly extinguish the arc.

Example

Referring to some preferred embodiments, the present invention will be described in detail. However, the present invention is not limited to these Examples.

Example 1

First, 67 parts by weight of polyolefin resin ("EVAL-L104B", product of Kuraray Co., Ltd.) and 25 parts by weight of polyoxymethylene-acetaldehyde copolymer ("Tenac-C 4520", product of Asahi Kasei Corporation) were melt-mixed, The polyolefin resin contains 0.58 mol of hydroxyl groups per 1 mol of methylene, and the polyoxymethylene-acetaldehyde copolymer contains 90 mol% of repeating units derived from formaldehyde. Then, 8 parts by weight of the compound of formula (I-14) was added as a reactive organophosphorus flame retardant. The resulting mixture was kneaded at 220° C. using a side-flow type twin-screw extruder (manufactured by Japan Steel Works, Ltd.) to obtain resin pellets. The resin pellets were dried at 80°C for 7 hours, and then molded using an injection molding machine (α50C type, manufactured by FANUC Ltd.) at a resin temperature of 215°C and a die temperature of 50°C. The cross-section of the molded product was observed by SEM to determine the microphase separation structure, which showed a spherical structure with a thin layer configuration and a uniform sea-island structure.

The shaped article was then irradiated with gamma-rays from a cobalt-60 source at a dose of 25 kGy. The arc extinguishing resin molded article of Example 1 was thus obtained. The cross-section of this arc-extinguishing resin molded product was observed with SEM, and the microphase separation structure was confirmed, showing a spherical structure having a thin-layer configuration and a uniform sea-island structure.

Example 2

First, 50 parts by weight of polyolefin resin ("EVAL-L104B", product of Kuraray Co., Ltd.) and 20 parts by weight of polyoxymethylene-acetaldehyde copolymer ("Tenac-C 4520", product of Asahi Kasei Corporation) were melt-mixed, The polyolefin resin contains 0.58 mol of hydroxyl groups per 1 mol of methylene, and the polyoxymethylene-acetaldehyde copolymer contains 90 mol% of repeating units derived from formaldehyde. Then, 10 parts by weight of boehmite (“BMT-10”, product of Kawai Lime Co., Ltd.) and 15 parts by weight of silane-treated glass fiber (“03.JAFT2Ak25”, product of Asahi Fiber Glass Co., Ltd. ) as an inorganic filler, and 5 parts by weight of a compound of formula (II-3) as a reactive organophosphorus flame retardant. The resulting mixture was kneaded at 220° C. using a side-flow type twin-screw extruder (manufactured by Japan Steel Works, Ltd.) to obtain resin pellets. The resin pellets were dried at 80°C for 7 hours, and then molded using an injection molding machine (α50C type, manufactured by FANUC Ltd.) at a resin temperature of 215°C and a die temperature of 50°C. The cross-section of the molded product was observed by SEM to determine the microphase separation structure, which showed a spherical structure with a thin layer configuration and a uniform sea-island structure.

The shaped article was then irradiated with gamma-rays from a cobalt-60 source at a dose of 25 kGy. The arc extinguishing resin molded article of Example 2 was thus obtained. The cross-section of this arc-extinguishing resin molded product was observed with SEM, and the microphase separation structure was confirmed, showing a spherical structure having a thin-layer configuration and a uniform sea-island structure.

Example 3

First, 53 parts by weight of polyolefin resin ("EVAL-L104B", product of Kuraray Co., Ltd.) and 20 parts by weight of polyoxymethylene-acetaldehyde copolymer ("Tenac-C 4520 ", Asahi Kasei Corporation product), the polyolefin resin contains 0.58 mol of hydroxyl groups relative to 1 mol of methylene, and the polyoxymethylene-acetaldehyde copolymer contains 90 mol% of repeating units derived from formaldehyde. Then, 15 parts by weight of boehmite ("BMT-10", a product of Kawai Lime Co., Ltd.) was added as an inorganic filler, and 12 parts by weight of a compound of formula (I-18) as a reactive organic phosphorus flame retardant. The resulting mixture was kneaded at 220° C. using a side-flow type twin-screw extruder (manufactured by Japan Steel Works, Ltd.) to obtain resin pellets. The resin pellets were dried at 80°C for 7 hours, and then molded using an injection molding machine (α50C type, manufactured by FANUC Ltd.) at a resin temperature of 215°C and a die temperature of 50°C. The cross-section of the molded product was observed by SEM to determine the microphase separation structure, which showed a spherical structure with a thin layer configuration and a uniform sea-island structure.

The shaped article was then irradiated with gamma-rays from a cobalt-60 source at a dose of 25 kGy. The arc extinguishing resin molded article of Example 3 was thus obtained. The cross-section of this arc-extinguishing resin molded product was observed with SEM, and the microphase separation structure was confirmed, showing a spherical structure having a thin-layer configuration and a uniform sea-island structure.

Comparative example 1

The resin pellets of Comparative Example 1 were obtained by kneading under the same conditions as in Example 1, except that no reactive organic phosphorus flame retardant was blended. The obtained pellets were dried at 80°C for 7 hours, and then molded using an injection molding machine (α50C type, manufactured by FANUC Ltd.) at a resin temperature of 215°C and a die temperature of 50°C. The arc extinguishing resin molded article of Comparative Example 1 was thus obtained.

Comparative example 2

The resin pellets of Comparative Example 2 were obtained by kneading under the same conditions as in Example 2, except that no reactive organic phosphorus flame retardant was blended. The obtained pellets were dried at 80°C for 7 hours, and then molded using an injection molding machine (α50C type, manufactured by FANUC Ltd.) at a resin temperature of 215°C and a die temperature of 50°C. The arc extinguishing resin molded article of Comparative Example 2 was thus obtained.

Comparative example 3

The arc-extinguishing resin molded article of Comparative Example 3 was obtained by kneading in the same manner as in Example 2, except that the reactive organic phosphorus flame retardant used in Example 2 was replaced by organic Phosphorus flame retardant ("HCA-HQ", product of Sanko Chemical Industry Co., Ltd.) instead.

Comparative example 4

The arc-extinguishing resin molded article of Comparative Example 4 was obtained by kneading in the same manner as in Example 2, except that the reactive organic phosphorus flame retardant used in Example 2 was replaced by a bromine-containing flame retardant ("Great Lakes pdbs-80", Great Lakes Chemical Corporation product) instead.

Comparative Example 5

The arc-extinguishing resin molded article of Comparative Example 5 was obtained by kneading in the same manner as in Example 2, except that Example 2 used a polyolefin resin containing 0.58 mol of hydroxyl groups per 1 mol of methylene ("EVAL -L104B", product of Kuraray Co., Ltd.) was replaced by polyethylene resin ("HJ362", product of NipponPolyethylene Corporation).

Comparative example 6

First, using a kneader, 25 parts by weight of unsaturated polyester resin ("7525", product of Japan U-PiCACo., Ltd.), 35 parts by weight of Al(OH) ₃ , and 5 parts by weight of styrene-vinyl acetate were copolymerized Compound, 0.3 parts by weight of tert-butyl peroxy-Z polymerization initiator and 4-7 parts by weight of viscosity regulator are kneaded together. During the kneading, 35 parts by weight of an inorganic filler of silane-treated glass fiber ("03. JAFT2Ak25, product of Asahi Fiber Glass Co., Ltd.) was added and dispersed to obtain a bulk molding compound. The bulk molding compound was Molding and polymerization were carried out at a temperature range of 140-150° C. In this way, an arc-extinguishing resin molded article of Comparative Example 6 was obtained.

Comparative Example 7

Resin pellets were obtained by kneading 99.8 parts by weight of nylon 6 resin ("UBE nylon 101 5B", product of UBE Industries, Ltd.) and 0.2 parts by weight of antioxidant ("IRGANOX 1010", supplied by Nihon Ciba-Geigie KK). The resin pellets were dried at 105°C for 4 hours, and then molded using an injection molding machine (α50C type, manufactured by FANUC Ltd.) at a resin temperature of 260°C and a die temperature of 85°C. The arc extinguishing resin molded article of Comparative Example 7 was thus obtained.

The molding properties of the arc-extinguishing resin molded articles obtained in Examples 1 to 3 and Comparative Examples 1 to 7 were evaluated. The resin molded product was used in the arc extinguishing chamber 13 of the circuit breaker shown in FIG. 1, and the arc extinguishing resin molded product was subjected to short circuit test, heat resistance test and flame retardancy test.

In the short-circuit test, a 3-phase 440V/50kA current passes through the contact piece in the closed state, and then, the movable contact part is opened to generate an arc current. The nature of the interruption of this arc current (arc extinguishing performance), disconnection and damage to the arc extinguishing device (voltage resistance) and the surface condition (heat resistance) are tested.

The current interruption property is designated as "acceptable" when the short circuit current is successfully interrupted.

Molding properties were designated as "acceptable" when the occurrence of bubbles or dripping during molding could not be detected by visual inspection.

Flame retardant properties were evaluated according to the following UL-94 test. Test pieces (5 inches long, 1/2 inch wide and 3.2 mm thick) were prepared according to UL-94. The test piece was held vertically and placed in contact with the flame of a Bunsen burner for 10 seconds, and the burning time was recorded. After extinguishing, the test piece was brought into contact with the flame again for 10 seconds, and the burning time was recorded. Distinguished according to UL-94 based on the total time to burn, the time to red heat combustion (glow) after secondary extinguishment, and the presence of droplets to ignite the cotton.

The status of metal contamination is evaluated by measuring the contact resistance of the sample left in an environment of 120°C for 300 hours. Metal contamination conditions are designated as "acceptable" when the contact resistance is not higher than 50 mΩ.

The results of the above tests are listed in Table 1.

Table 1

Try short circuit molding properties Flame retardant properties (UL-94) metal pollution Short circuit interruption properties (arc extinguishing performance) Disconnection & damage (pressure resistance) Surface Condition (Heat Resistance) Example 1 Acceptable (good current interruption properties) acceptable (no damage) good good V-0 acceptable Example 2 Acceptable (good current interruption properties) acceptable (no damage) good good V-0 acceptable Example 3 Acceptable (good current interruption properties) acceptable (no damage) good good V-0 acceptable Comparative example 1 Acceptable (good current interruption properties) damage good good HB acceptable Comparative example 2 Acceptable (good current interruption properties) damage good good HB acceptable Comparative example 3 Acceptable (good current interruption properties) damage good good V-2 unacceptable Comparative example 4 Acceptable (good current interruption properties) damage good good V-0 unacceptable Comparative Example 5 unacceptable damage good good HB acceptable Comparative example 6 Acceptable (good current interruption properties) damage good Poor (produce mold flash) V-1 acceptable Comparative Example 7 Acceptable (good current interruption properties) damage good Poor (dripping observed) HB acceptable

As is clear from the results in Table 1, the arc-extinguishing resin molded articles of Examples 1 to 3 showed good flame retardancy, heat resistance and molding properties. Circuit breakers using arc extinguishing devices made of these arc extinguishing resin molded products can effectively extinguish the arc generated between the contact pieces during current interruption, and no damage is observed in the arc extinguishing chamber due to the arc extinguishing effect Phenomenon.

Claims (9)

1. arc extinguishing resin molding goods, these goods comprise resin combination, said composition contains polyolefin resin (A), also comprise reactive organophosphorous fire retardant (B) with unsaturated end key, in the described resin (A), the part of the hydrogen atom in methene chain is replaced by hydroxyl, and the content of hydroxyl is in the 0.2-0.7mol scope with respect to the 1mol methylene radical, this molded resin carries out irradiation after moulding, crosslinked to carry out.

2. arc extinguishing molded resin as claimed in claim 1, it is characterized in that, described resin combination also comprises polyacetal resin (C), its content is to be the 5-90 weight part with respect to 100 weight part polyolefin resines (A), polyacetal resin (C) contains the repeating unit that is derived from formaldehyde, and its ratio is in the 75-100mol% scope.

3. arc extinguishing molded resin as claimed in claim 1 or 2, it is characterized in that, described resin combination also contains the mineral filler (D) that is selected from one or more following types: glass fibre, barium titanate palpus crystalline substance, aerosil particles, boehmite, talcum, magnesiumcarbonate and metal hydroxides, the content of mineral filler is in the scope of 1-70 weight %.

4. as each described arc extinguishing molded resin among the claim 1-3, it is characterized in that the decomposition latent heat of described polyolefin resin (A) is at least 30cal/g.

5. as each described arc extinguishing molded resin among the claim 1-4, it is characterized in that described polyolefin resin (A) is an ethylene-vinyl alcohol copolymer.

6. as each described arc extinguishing molded resin among the claim 1-5, it is characterized in that, described reactive organophosphorous fire retardant (B) is that the content of reactive organophosphorous fire retardant (B) is 0.5-20 weight % in the resin combination by the organo phosphorous compounds of following chemical formula (I) and/or chemical formula (II) expression;

In the formula, R ¹To R ⁴Represent CH separately ₂=CY ¹-Y ²-, or contain heteroatomic simple function aromatic hydrocarbon group, R ⁵Expression contains heteroatomic difunctionality aromatic hydrocarbon group;

X ¹To X ⁴Separately the expression be selected from following group :-O-,-NH-,-(CH ₂=CY ¹-Y ²) N-, and X ¹To X ⁴In at least one group contain-NH-or-(CH ₂=CY ¹-Y ²) N-;

R ¹To R ⁴And X ¹To X ⁴In at least one group contain CH ₂=CY ¹-Y ²-;

Y ¹Expression hydrogen atom or methyl; With

Y ²The expression carbon number be 1-5 alkylidene group or-COO-Y ³-, Y wherein ³The expression carbon number is the alkylidene group of 1-5;

In the formula, in a molecule, comprise at least one P-C key;

Ar ¹And Ar ²Represent that separately carbon number mostly is 20 and do not contain the difunctionality aromatic hydrocarbon group of the hydrogen that flows most, n is 0,1 or 2 integer; R ⁶To R ¹⁰Expression is selected from following group :-NHCH separately ₂CH=CH ₂,-N (CH ₂CH=CH ₂) ₂,-OCH ₂CH=CH ₂,-CH ₂CH=CH ₂,-CH ₂CH ₂OCH=CH ₂,-(C ₆H ₄)-CH=CH ₂,-O (C ₆H ₄)-CH=CH ₂,-CH ₂(C ₆H ₄)-CH=CH ₂,-NH (C ₆H ₄)-CH=CH ₂,-N (CH ₂CH=CH ₂)-(C ₆H ₄)-CH=CH ₂,-O-R-OOC-C (R ')=CH ₂,-NH-R-NHCO-C (R ')=CH ₂Mostly be most 12 aryl with carbon number, wherein R represents that carbon number is the alkylidene group of 2-5, R ' expression hydrogen atom or methyl;

R ⁶To R ¹⁰In at least one group contain-CH=CH ₂Group or-C (CH ₃)=CH ₂Group.

7. as each described arc extinguishing molded resin among the claim 2-6, it is characterized in that described polyacetal resin (C) is formaldehyde-acetaldehyde copolymer or yuban.

8. as each described arc extinguishing molded resin among the claim 2-7, it is characterized in that described polyacetal resin (C) is dispersed in the polyolefin resin (A), form micro phase separation structure.

9. an isolating switch comprises the fixed contact part with fixed contact piece; Removable contact part, it has removable contactor segment and contacts to reach with the fixed contact part, and carries out closure and opening action with the fixed contact part; And the arc extinguishing device, the electric arc that produces when being used for eliminating the open and close action between fixed contact part and removable contact part; Wherein, the arc extinguishing device comprises as each described arc extinguishing resin molding goods among the claim 1-8.

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