JP2009096979A - Dielectric elastomer composition and high-frequency electronic component material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric elastomer composition having excellent flame retardancy while considering environmental influence, while having sufficient dielectric characteristics as a high-frequency electronic component material, and a high-frequency electronic component material produced by molding the composition. <P>SOLUTION: The dielectric elastomer composition is produced by mixing magnesium a hydroxide powder containing ≤0.02 wt.% Fe<SB>2</SB>O<SB>3</SB>with an elastomer and has ≥3 relative dielectric constant and ≤0.006 dielectric dissipation factor, under either one of measurement conditions of (1) 400 MHz frequency at 30°C temperature or (2) 5 GHz frequency at 25°C temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dielectric elastomer composition having both excellent flame retardancy and dielectric properties, and a high frequency electronic component material formed by molding the composition.

  In recent years, with the remarkable spread of patch antennas used for mobile phones, cordless phones, RFID, etc., lens antennas such as radio telescopes and millimeter wave radars, and the remarkable development of satellite communication equipment, the frequency of communication signals has increased and the frequency of communication equipment has increased. Further downsizing is desired. In the communication device, when the relative dielectric constant of the antenna material incorporated in the communication device is increased, the frequency can be further reduced and the size can be reduced. The relative dielectric constant is a parameter indicating the degree of polarization inside the dielectric, and the dielectric loss tangent is a parameter indicating energy loss caused by polarization inside the dielectric and imparting conductivity. Therefore, if an antenna material having a high relative dielectric constant can be used, high frequency can be increased, and therefore the circuit can be shortened and the communication device can be miniaturized. In addition, as communication devices are used in various ways, antenna materials have less change in electrical characteristics from low temperature to high temperature, less frequency dependence of electrical characteristics, and excellent flame retardancy. It has been demanded.

Conventionally, as a material for obtaining an antenna having a high relative dielectric constant and a low dielectric loss tangent over a wide temperature range from a low temperature to a high temperature, an elastomer such as ethylene propylene rubber is used in a temperature range of −40 ° C. to 100 ° C. A dielectric elastomer composition containing a barium-neodymium ceramic powder or the like having a relative dielectric constant temperature coefficient α (unit: 1 / ° C.) in the range of (−200 to 100) × 10 ⁻⁶ is known ( Patent Document 1).

On the other hand, as a measure for improving the flame retardancy of antenna materials, brominated or chlorinated halogen flame retardants such as polybromodiphenyl ether (hereinafter referred to as PBDE) and polybromobiphenyl (hereinafter referred to as PBB) have been conventionally used. It is known to blend. Moreover, in the case of brominated flame retardants other than PBB and PBDE, antimony trioxide is usually used in combination in order to increase flame retardancy.
In general, in order to improve flame retardancy in an elastomeric material, it is known to blend a metal hydroxide, expanded graphite and the like in addition to the halogen flame retardant. It is known that the metal hydroxide is blended in, for example, an elastomeric material that constitutes a transfer belt or the like of an electrophotographic apparatus (see Patent Document 2).

However, the dielectric elastomer composition of Patent Document 1 has excellent dielectric properties with little change in electrical properties from low temperature to high temperature, but does not contain a flame retardant and is used for applications where flame retardancy is required. There is a problem that it cannot be used.
In order to improve the flame retardancy of such a dielectric elastomer composition, when the halogen flame retardant is used as a flame retardant, dioxins may be generated from the halogen flame retardant at the time of disposal, which is not environmentally preferable. . In particular, PBB and PBDE cannot be used in electrical and electronic products according to the European Union (EU) RoHS Directive (restriction on the use of specific hazardous substances in electrical and electronic equipment) established in January 2003.
Although brominated flame retardants other than PBB and PBDE are not prohibited, antimony trioxide is used in combination with the antimony trioxide as described above, and lead, mercury, hexavalent chromium, cadmium as impurities Etc. are not preferable because they are contained in trace amounts.

In the case of using a metal hydroxide as in Patent Document 2, the flame retardant effect is difficult to be obtained unless it is contained in a large amount, and generally a dielectric loss tangent is increased when it is contained in a large amount. It is not known for use in applications where tangent is required. Further, it is not preferable that the metal hydroxide contains a large amount of impurities such as ferric trioxide, calcium oxide, and silicon dioxide because the dielectric loss tangent increases.
Further, when the expanded graphite is blended in the antenna material, the flame retardancy is improved, but the dielectric property is extremely deteriorated, which is not preferable.
JP 2006-1989 JP 2005-97493 A

  The present invention has been made in order to cope with such problems, and has an excellent flame retardancy while considering the influence on the environment, and a dielectric elastomer composition having sufficient dielectric properties as a high frequency electronic component material It is an object of the present invention to provide a high-frequency electronic component material obtained by molding a product and the composition.

The dielectric elastomer composition of the present invention is a dielectric elastomer composition obtained by blending magnesium hydroxide powder having a ferric trioxide (hereinafter referred to as Fe ₂ O ₃ ) content of 0.02 wt% or less into an elastomer. Under the measurement conditions of (1) frequency 400 MHz and temperature 30 ° C., (2) frequency 5 GHz and temperature 25 ° C., the dielectric elastomer composition has a relative dielectric constant of 3 or more and a dielectric loss tangent. It is characterized by being 0.006 or less.

The magnesium hydroxide powder is characterized in that the content of calcium oxide (hereinafter referred to as CaO) is 0.2% by weight or less. The magnesium hydroxide powder is characterized in that the content of silicon dioxide (hereinafter referred to as SiO ₂ ) is 0.2% by weight or less.

  The magnesium hydroxide powder is subjected to a surface treatment. The magnesium hydroxide powder has an average particle size of 10 μm or less.

  The dielectric elastomer composition is characterized by blending dielectric ceramic powder. The dielectric elastomer composition is characterized by blending a brominated flame retardant excluding PBDE and PBB.

  The elastomer is at least one elastomer selected from styrene-based and olefin-based elastomers. The elastomer is ethylene propylene rubber.

The high-frequency electronic component material of the present invention is a high-frequency electronic component material for handling an electric signal having a frequency of 100 MHz or more, and is characterized by using a molded body of the dielectric elastomer composition.
Further, it is characterized in that it is obtained by pasting an electrode on the surface of the dielectric elastomer molded body or by insert molding an electrode inside the molded body.

The dielectric elastomer composition of the present invention is a dielectric elastomer composition obtained by blending an elastomer with magnesium hydroxide powder having an Fe ₂ O ₃ content of 0.02 wt% or less, and (1) a frequency of 400 MHz and Since the relative dielectric constant of the dielectric elastomer composition is 3 or more and the dielectric loss tangent is 0.006 or less under the measurement conditions of temperature 30 ° C, (2) frequency 5 GHz and temperature 25 ° C, high frequency electronic components While maintaining sufficient dielectric properties as a material, it has excellent flame retardancy.

By blending magnesium hydroxide powder, the flame retardancy of the dielectric material is improved. In particular, as the impurity concentration of the magnesium hydroxide powder, Fe ₂ O ₃ can be reduced dissipation factor in the use of those 0.02 wt% or less. Moreover, the dielectric loss tangent can be lowered by using CaO of 0.2% by weight or less. Moreover, the dielectric loss tangent can be lowered by using SiO ₂ having a content of 0.2% by weight or less.

Further, since the surface treatment is performed on the magnesium hydroxide powder, the water absorption rate of the magnesium hydroxide powder is lowered and the kneadability of the magnesium hydroxide powder in the dielectric elastomer composition is improved.
Further, since the average particle diameter of the magnesium hydroxide powder is 10 μm or less, the dispersibility of magnesium hydroxide in the dielectric elastomer composition is improved.

  Moreover, since the said dielectric elastomer composition mix | blends dielectric ceramic powder, it can make a dielectric constant higher than the case where it is not mix | blended.

  Also, by using magnesium hydroxide powder and brominated flame retardant together, excellent flame retardancy can be secured without using antimony trioxide while using brominated flame retardants other than PBDE and PBB. Preferred above. Moreover, compared with the case where a flame retardant is only magnesium hydroxide powder, the compounding quantity of magnesium hydroxide powder can be decreased, and it can suppress that a moldability deteriorates or a dielectric loss tangent becomes high.

  Since the high-frequency electronic component material of the present invention is formed by molding the above dielectric elastomer composition, it is excellent in flame retardancy while maintaining a dielectric property in which a high relative dielectric constant and a low dielectric loss tangent are compatible.

As described above, in the case of using a metal hydroxide such as magnesium hydroxide powder as a flame retardant, the flame retardant effect is difficult to be obtained unless it is contained in a large amount, and generally the dielectric loss tangent is increased when it is contained in a large amount. Metal hydroxide was not used in antenna materials.
The inventors of the present invention pay attention to the fact that the magnesium tangent powder used as a flame retardant has a high dielectric loss tangent because the impurity concentration has a large influence, and the concentration of impurities such as Fe ₂ O ₃ is below a certain value. By using this magnesium hydroxide powder, a dielectric elastomer composition having both sufficient dielectric properties and flame retardancy as an antenna material was obtained. The present invention is based on the above findings.

The magnesium hydroxide powder used in the present invention must have an impurity concentration of Fe ₂ O ₃ of 0.02% by weight or less. When the content exceeds 0.02% by weight, the dielectric loss tangent is increased, which is not preferable.
Moreover, it is preferable that CaO is 0.2 weight% or less as an impurity concentration. When CaO exceeds 0.2% by weight, the dielectric loss tangent is increased, which is not preferable.
Further, it is preferable that the impurity concentration SiO ₂ is less than 0.2 wt%. When SiO ₂ exceeds 0.2% by weight, the dielectric loss tangent is increased, which is not preferable.

Magnesium hydroxide used in the present invention can absorb heat and release water molecules by causing an endothermic dehydration reaction under high heat, thereby providing flame retardancy by lowering the temperature. The decomposition temperature of magnesium hydroxide is about 300 to 350 ° C.
The magnesium hydroxide powder preferably has a BET specific surface area of 1 to 20 m ² / g or less and an average particle size of 0.1 to 50 μm. In particular, in order to improve the dispersibility of the magnesium hydroxide powder in the dielectric elastomer composition, the average particle size is preferably 10 μm or less.
In addition, the above magnesium hydroxide powder improves dispersibility, processability, etc., so that silane coupling agents, titanate coupling agents, epoxy surface treatment agents, higher fatty acids or salts thereof, higher alcohols, surfactants, etc. It is preferable to apply a surface treatment.

In the present invention, as a surface treatment method using a silane coupling agent applied to magnesium hydroxide, a dry method or a wet slurry method can be employed. In addition to performing surface treatment in advance as described above, a silane coupling agent can also be added to the dielectric elastomer composition and surface treatment can be performed while mixing.
In addition, when magnesium hydroxide is surface-treated with a higher fatty acid or a salt thereof, a method in which the higher fatty acid or a salt thereof is dissolved and sprayed, and the surface is treated by a dry method using a Henschel mixer or the like can be employed. Examples of higher fatty acids and salts thereof include stearic acid, oleic acid, palmitic acid, lauric acid, and sodium and potassium salts thereof.

As a commercial item of magnesium hydroxide that can be used in the present invention, manufactured by Kamishima Chemical Industry Co., Ltd .: N-6 (average particle size 1.3 μm, surface treatment: saturated fatty acid, impurity concentration: Fe ₂ O ₃ : 0.001 to 0.003 wt%, SiO ₂ : 0.03 to 0.05 wt%, CaO: 0.1 to 0.15 wt%, manufactured by Kyowa Chemical Co., Ltd .: Kisuma 5A (average particle size 0.85 μm, surface treatment: saturated fatty acid, impurity concentration: Fe ₂ O ₃ : 0.0001 to 0.001 wt. %, SiO ₂ : 0.01 to 0.05% by weight, CaO: 0.01 to 0.15% by weight) and 5B (average particle size 0.87 μm, surface treatment: unsaturated fatty acid, impurity concentration: Fe ₂ O ₃ : 0.0001 to 0.001% by weight, SiO ₂ : 0.01 to 0.05% by weight, CaO: 0.01 to 0.15% by weight), manufactured by Sakai Chemical Co., Ltd .: MGZ-1 (average particle size 0.8 μm, surface treatment: unsaturated fatty acid, impurity concentration: Fe ₂ O ₃ : 0.0005 to 0.02 weight%, SiO _2: 0.01~0.2 weight%, CaO: 0.01~0.15 double %) And MGZ-3 (average particle diameter 0.1 [mu] m, surface treatment: unsaturated fatty acids, impurity concentration: Fe ₂ O _3: 0.0005-0.02 wt%, SiO _2: 0.01 to 0.2 wt%, CaO: 0.01 to 0.15 wt% ) And the like.

In addition to the magnesium hydroxide powder, taking into consideration the burden on the environment and imparting flame retardancy, a necessary minimum amount of a flame retardant such as bromine having a large flame retardant effect may be added.
As the brominated flame retardant, any brominated flame retardant excluding PBDE and PBB can be used. For example, ethylene bispentabromobenzene, decabromodiphenyl ether, TBA-bis (2,3-dibromopropyl ether), bis (3,5-dibromo-4-dibromopropyloxyphenyl) sulfone, triallyl isocyanate hexabromide, hexabromo Examples thereof include cyclododecane, octabromodiphenyl ether, tetrabromobisphenol A, ethylene bistetrabromophthalimide, brominated polystyrene, and the like.
Of these, ethylene bispentabromobenzene and decabromodiphenyl ether are preferred because of their high melting point of 300 ° C. or higher and bromination rate of 80% or higher. As a commercial product of ethylenebispentabromobenzene, Suzuhiro Chemical Co., Ltd .: FCP801, and as a commercial product of decabromodiphenyl ether, Suzuhiro Chemical Co., Ltd .: FCP83D can be mentioned.

The blending ratio of the magnesium hydroxide powder in the dielectric elastomer composition of the present invention is preferably 300 to 600 parts by weight with respect to 100 parts by weight of the elastomer when a brominated flame retardant is not used in combination. More preferably, it is 300 to 450 parts by weight.
If the amount is less than 300 parts by weight, sufficient flame retardancy (specifically, tests described in the examples described later) cannot be obtained. On the other hand, if it exceeds 600 parts by weight, the dielectric loss tangent will exceed 0.006 depending on the temperature, and the dielectric properties required for high frequency electronic component materials cannot be satisfied.
Moreover, when using a brominated flame retardant together, it is preferable that it is 100-600 weight part with respect to 100 weight part of elastomers. More preferably, it is 150 to 300 parts by weight. If the blending ratio of magnesium hydroxide powder is less than 100 parts by weight, it is necessary to blend more than 100 parts by weight of brominated flame retardant to ensure flame retardancy, resulting in poor formability and high dielectric loss tangent. In addition, it is not environmentally preferable. When the magnesium hydroxide powder exceeds 600 parts by weight, there are problems such as poor formability and high dielectric loss tangent.

  As the elastomer constituting the dielectric elastomer composition of the present invention, a natural rubber elastomer and a synthetic rubber elastomer can be used. The elastomer used in the present invention is preferably an elastomer having a specific gravity of 0.8 to 1.1 at 25 ° C. If the specific gravity is less than 0.8, the strength is low due to the low molecular weight, and the number of pores in the molded product increases, such being undesirable. In addition, if the specific gravity exceeds 1.1, the product weight increases, which is not preferable.

  Natural rubber elastomers include natural rubber, chlorinated rubber, hydrochloric acid rubber, cyclized rubber, maleated rubber, hydrogenated rubber, and vinyl monomers such as methyl methacrylate, acrylonitrile, and methacrylic acid ester grafted onto the double bond of natural rubber. Examples thereof include a graft-modified rubber, a block polymer obtained by roughening natural rubber in the presence of a monomer in a nitrogen stream. These may include elastomers made from synthetic cis-1,4-polyisoprene as well as those made from natural rubber.

  Synthetic rubber elastomers include polyolefin elastomers such as isobutylene rubber, ethylene propylene rubber, ethylene propylene diene rubber, ethylene propylene terpolymer, chlorosulfonated polyethylene rubber, styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene- Styrene elastomers such as styrene copolymer (SBS), styrene-ethylene-butylene-styrene block copolymer (SEBS), isoprene rubber, urethane rubber, epichlorohydrin rubber, silicone rubber, nylon 12, butyl rubber, butadiene rubber, polynorbornene rubber, acrylonitrile- Examples thereof include butadiene rubber.

These elastomers can be used alone or in combination of two or more. Further, one or more types of thermoplastic resins can be blended and used within a range that does not impair the elasticity of the elastomer.
In the present invention, among the above-mentioned elastomers, it is preferable to use at least one elastomer selected from styrene-based elastomers and olefin-based elastomers because of excellent electrical characteristics. In particular, ethylene propylene rubber and ethylene propylene diene rubber have a very low dielectric loss tangent, and therefore can be preferably used as high frequency electronic component materials such as antenna members.

In order to improve the dielectric constant of the dielectric elastomer composition of the present invention, it is preferable to blend a dielectric ceramic powder.
The dielectric ceramic powder that can be used in the present invention is selected from Group IIa, IVa, IIIb, and IVb group oxides, carbonates, phosphates, silicates, and complex oxides including Group IIa, IVa, IIIb, and IVb groups. It is preferable that it is at least one. Specifically, TiO ₂ , CaTiO ₃ , MgTiO ₃ , Al ₂ O ₃ , BaTiO ₃ , SrTiO ₃ , Ca ₂ P ₂ O ₇ , SiO ₂ , Mg ₂ SiO ₄ , Ca ₂ MgSi ₂ O ₇ , or relative dielectric In order to improve the temperature dependency of the rate, BaO—TiO ₂ —Nd ₂ O ₃ based ceramics containing an alkaline earth metal and a rare earth oxide can be used. Moreover, you may mix | blend trace compositions, such as Al and Zr, for a characteristic improvement.

  The average particle size of the dielectric ceramic powder is preferably about 0.01 to 100 μm. When it is smaller than 0.01 μm, it is difficult to handle and unfavorable because binding properties are inhibited. If it is larger than 100 μm, it is not preferable because it may cause variation in dielectric properties in the molded body. A more practical range is about 0.1 to 20 μm.

  The blending ratio of the dielectric ceramic powder in the dielectric elastomer composition of the present invention is preferably 50 to 1000 parts by weight with respect to 100 parts by weight of the elastomer. By blending the dielectric ceramic powder within the above range, the relative dielectric constant can be improved by about 1 to 20 compared with the case of not blending.

  In the present invention, in order not to interfere with the effects of the present invention (1) In order to improve the affinity and bondability of the interface between the elastomer and the ceramic powder and improve the mechanical strength, Coupling agents such as titanate coupling agents and zirconia aluminate coupling agents, and (2) fine particle fillers such as talc and calcium pyrophosphate to improve plating properties for electrode formation (3 ) Antioxidants to further improve thermal stability, (4) Light stabilizers such as UV absorbers to improve light resistance, and (5) Impact resistance to improve impact resistance. (6) Coloring agents such as dyes and pigments for coloring, (7) Plasticizers for adjusting physical properties, crosslinking agents such as sulfur and peroxides, and (8) For proceeding with vulcanization Each vulcanization accelerator It can be formulated.

  Further, the dielectric elastomer composition of the present invention includes glass fiber, alkali metal titanate fibers such as potassium titanate whisker, titanium oxide fiber, magnesium borate whisker and aluminum borate within a range not impairing the object of the present invention. Various organic or inorganic fillers such as metal borate fibers such as whisker, metal silicate fibers such as zinc silicate whisker and magnesium silicate whisker, carbon fiber, alumina fiber, and aramid fiber can be used in combination.

The method for producing the dielectric elastomer composition of the present invention is not particularly limited, and various mixed molding methods can be used. For example, the above-mentioned magnesium hydroxide, dielectric ceramic powder, various additives, vulcanizing agents, etc. are blended in an elastomer, and this is kneaded with a Banbury mixer, roller, biaxial extruder, etc. It is done.
The obtained dielectric elastomer composition can be molded by injection molding, extrusion molding, heat compression molding, or the like to obtain a molded body of the dielectric elastomer composition.

  The dielectric elastomer composition of the present invention has a relative dielectric constant of at least one of (1) a frequency of 400 MHz and a temperature of 30 ° C. and (2) a frequency of 5 GHz and a temperature of 25 ° C. Is 3 or more and the dielectric loss tangent is 0.006 or less. In any of the above (1) and (2), the case where the above physical properties are satisfied is preferable because the frequency dependence of electrical characteristics is small. In the manufacturing process described above, dielectric ceramic powders other than the above-described magnesium hydroxide powder and brominated flame retardant are blended at a ratio satisfying the above physical properties.

The high-frequency electronic component material of the present invention has an electrode bonded to the surface of the above-mentioned dielectric elastomer composition molded body, or a dielectric elastomer bonded to both surfaces of the electrode, or the inside of the dielectric elastomer molded body. The electrode can be easily obtained by insert molding.
For example, Kyocera Chemical's TFA-880CC, TFA-890EA, Shin-Etsu Chemical Co., Ltd. it can. In addition, it is also possible to apply and bond an adhesive.
In addition, insert molding can be performed by filling a molding die having an electrode at a predetermined position with a dielectric elastomer composition.

Examples 1 to 7 and Comparative Examples 1 to 4
Ethylene propylene rubber (manufactured by JSR: EP35), magnesium hydroxide (manufactured by Kamishima Chemical Co., Ltd .: surface treatment with N-6 or N-4 higher fatty acid), brominated flame retardant (manufactured by Suzuhiro Chemical Co., Ltd .: FCP801) ), Dielectric ceramic powder (manufactured by Kyoritsu Material Co., Ltd .: STNAS), carbon black (manufactured by Tokai Carbon Co., Ltd .: Seast S), and process oil (manufactured by Idemitsu Kosan Co., Ltd .: PW380) at the blending ratios shown in Table 1 After mixing, a vulcanization accelerator and a processing aid were added, and the mixture was kneaded with a pressure kneader, and a compact of 150 mm × 150 mm × 2.0 mm was obtained by heat compression molding. The vulcanization conditions are 170 ° C x 20 minutes each.
With respect to the molded bodies of the dielectric elastomer compositions obtained in the respective examples and comparative examples, measurement of relative dielectric constant and dielectric loss tangent by capacity method and cavity resonator method, evaluation of moldability, and flame retardancy test were performed as follows. By the method. In Example 2, measurement was performed only by the capacitance method, and in Example 7, measurement was performed only by the cavity resonator method. The results are also shown in Table 1.

Comparative Example 5 to Comparative Example 7
Magnesium hydroxide was treated in the same manner as in Example 1 using N-6 manufactured by Kamishima Chemical Co., Ltd., and the moldability was evaluated by the following method. The results are also shown in Table 1.

<Measurement of dielectric constant and dielectric loss tangent by capacitance method>
A 20 mm × 20 mm × 1.5 mm molded body test piece was cut out from the obtained molded body, and the relative dielectric constant and dielectric loss tangent were measured based on 30 ° C. in the frequency band of 400 MHz by the capacitance method. The measurement apparatus used for the capacitance method was an impedance analyzer: E4991A (manufactured by Agilent Technologies), and the electrode was 16453A (manufactured by Agilent Technologies).

<Measurement of dielectric constant and dielectric loss tangent by cavity resonator method>
A 1.5 mm × 1.5 mm × 80 mm strip-shaped test piece was processed from the obtained molded body, and 1, 3 using a cavity resonator method (July 1998, Electronic Monthly, pages 16 to 19). The relative dielectric constant and dielectric loss tangent at 25 ° C were measured in the 5 GHz frequency band.

<Evaluation of formability>
If the molded product of 150 mm x 150 mm x 2.0 mm sufficiently flows to the four corners and fills up to the end, it is evaluated that it is excellent in moldability, and "○" does not flow sufficiently to the four corners, and is insufficiently filled In the case of the occurrence of, it is evaluated that the moldability is inferior and “x” is recorded.

<Flame retardance test>
The obtained molded body was subjected to a UL94HB combustion test based on ASTM D635 or a UL94V combustion test based on ASTM D3801, and the flame retardancy rating defined by each test method was obtained for the flame retardancy of the molded body. “X” is recorded as a notation indicating that flame retardancy is not recognized or less than HB.

As shown in Table 1, Examples 1 to 7 were excellent in flame retardancy and had a low dielectric loss tangent. In addition, almost no increase in dielectric loss tangent with increasing measurement frequency (1-5 GHz) was observed. On the other hand, in Comparative Examples 1 to 4, the dielectric loss tangent increased because of the large amount of magnesium hydroxide impurities used. In addition, an increase in dielectric loss tangent was observed with an increase in measurement frequency (1 to 5 GHz).
In Comparative Example 5 using magnesium hydroxide that was not subjected to surface treatment, the affinity between the ethylene propylene rubber and the magnesium hydroxide powder was poor and the stirring resistance during kneading was large, resulting in poor moldability. In Comparative Example 6, since the filling amount of the magnesium hydroxide powder was large, the resistance during kneading was large, and a good molded product could not be obtained. In Comparative Example 7, since the ceramic powder was filled in a large amount, the resistance during kneading was large, and a good molded product could not be obtained.

  The dielectric elastomer composition of the present invention has a low environmental impact, has excellent flame retardancy, has a low dielectric loss tangent, and even if the frequency used increases, the dielectric loss tangent hardly increases. It can be suitably used as a material for electronic parts.

Claims (11)

A dielectric elastomer composition comprising an elastomer mixed with magnesium hydroxide powder having a ferric trioxide content of 0.02 wt% or less,
(1) In a measurement condition of a frequency of 400 MHz and a temperature of 30 ° C. and (2) a frequency of 5 GHz and a temperature of 25 ° C., the dielectric elastomer composition has a relative dielectric constant of 3 or more and a dielectric loss tangent of 0.006 or less. A dielectric elastomer composition characterized by comprising:   2. The dielectric elastomer composition according to claim 1, wherein the magnesium hydroxide powder has a calcium oxide content of 0.2% by weight or less.   3. The dielectric elastomer composition according to claim 1, wherein the magnesium hydroxide powder has a silicon dioxide content of 0.2% by weight or less.   4. The dielectric elastomer composition according to claim 1, wherein the magnesium hydroxide powder has been subjected to a surface treatment.   The dielectric elastomer composition according to any one of claims 1 to 4, wherein the magnesium hydroxide powder has an average particle size of 10 µm or less.   The dielectric elastomer composition according to any one of claims 1 to 5, wherein the dielectric elastomer composition comprises a dielectric ceramic powder.   The dielectric elastomer composition according to any one of claims 1 to 6, wherein the dielectric elastomer composition contains a brominated flame retardant excluding polybromodiphenyl ether and polybromobiphenyl. .   The dielectric elastomer composition according to any one of claims 1 to 7, wherein the elastomer is at least one elastomer selected from styrene-based elastomers and olefin-based elastomers.   The dielectric elastomer composition according to any one of claims 1 to 8, wherein the elastomer is ethylene propylene rubber. A high-frequency electronic component material for handling electrical signals with a frequency of 100 MHz or higher,
A high frequency electronic component material comprising the molded body of the dielectric elastomer composition according to any one of claims 1 to 9.   11. The high frequency electronic component material according to claim 10, wherein the material is obtained by pasting an electrode on a surface of the dielectric elastomer molded body or by insert molding an electrode inside the molded body.