JP2006274179A - High dielectric elastomer composition and electronic part for high frequency - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high dielectric elastomer composition being compounded with a high dielectric ceramic which is obtained by the self-propagating high-temperature synthesis, can achieve a wide particle distribution and a high filling rate, and has excellent dielectric property, and also to provide an electronic parts for high frequency using the above material. <P>SOLUTION: The composition comprises an elastomer and a high dielectric ceramic which is obtained by the self-propagating high-temperature synthesis method wherein reaction materials respectively comprising a metal powder containing a Group 4 element and having a specific surface area of 0.01-2 m<SP>2</SP>/g, a carbonate containing a Group 2 element and a substance generating oxygen by heating are compounded in predetermined amounts and the adiabatic flame temperature is 1,500°C or higher, and which has a specific permittivity of 15 or higher. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high dielectric elastomer composition and a high frequency electronic component, and in particular, a high dielectric elastomer composition that can be used for an electronic component such as an antenna used in a high frequency region, a sensor, an electronic component that requires electric field relaxation, and the like. Related to things.

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 devices, the frequency of communication signals has increased and the frequency of communication devices has increased. Further downsizing is desired.
As for the frequency of the communication signal and the size of the communication device, for example, when the relative dielectric constant of the antenna substrate incorporated in the communication device is increased, the frequency and size can be further reduced. The relative dielectric constant is a parameter indicating the degree of polarization inside the dielectric, and the higher the relative dielectric constant of the high dielectric elastomer composition used for the antenna material, the shorter the wavelength of the signal propagating through the electronic component circuit, The signal becomes high frequency. Therefore, if an electronic component having a high relative dielectric constant can be used, the frequency can be increased, the circuit can be shortened, and the communication device can be downsized.

In order to produce a high dielectric elastomer composition, a high dielectric ceramic powder is generally blended with the elastomer.
However, for the synthesis of conventional high dielectric ceramics, external heating must be performed using a furnace capable of heating from about 1000 ° C. to about 2000 ° C. For this reason, the synthesis of ceramics requires enormous energy and a large heating mechanism, which increases the manufacturing cost.
As a manufacturing method in which external heating is not performed, synthesis of ceramic powder by a combustion synthesis method has been proposed (Patent Document 1).
The combustion synthesis method is a method of synthesizing substances in a chain manner by utilizing a large amount of chemical heat reaction released at the time of compounding without requiring external heating.
In the production method according to Patent Document 1, three kinds of raw materials, one kind of metal oxide and two kinds of different metal elements, are used as starting materials, and two kinds of intermetallic compounds or non-oxide ceramics and oxide ceramics are synthesized. ing. For example, after mixing nickel oxide powder, aluminum powder, and alumina powder to form a compact, it is stored in a high-pressure reaction vessel, and the upper end surface of the compact is ignited in an argon atmosphere to oxidize and burn the aluminum powder. The combustion reaction proceeds in a chained manner while the reduced nickel reacts with the excessively added aluminum to synthesize NiAl. As a result, an ingot of NiTi that is one of intermetallic compounds can be manufactured without external heating.

However, in the above case, Al ₂ O ₃ synthesized simultaneously is said to be easily obtained from NiTi due to the difference in wettability, specific gravity, viscosity, melting point and thermodynamic stability with respect to NiTi. It is difficult to accurately separate these two kinds of composites, and there is a problem that the ceramic obtained by this manufacturing method is not a high dielectric material.
In addition, commercially available dielectric ceramic powders have a uniform average particle size and have a problem that it is difficult to highly fill the elastomer in order to increase the dielectric constant.
Japanese Patent Laid-Open No. 5-9009

  The present invention has been made in order to cope with such problems, and is obtained by combustion synthesis. The present invention is capable of widening the particle size distribution, and has high dielectric properties with excellent dielectric properties that can be highly filled. It is an object of the present invention to provide a high dielectric elastomer composition containing ceramics and a high frequency electronic component using this material.

The high dielectric elastomer composition of the present invention comprises a high dielectric ceramic mixed with an elastomer, and the high dielectric ceramic is a metal powder containing a Group 4 element having a specific surface area of 0.01 to ² m ² / g ( Hereinafter, a carbonate of an element containing a Group 2 element (hereinafter abbreviated as Group 4 metal powder), a substance that generates oxygen by heating (hereinafter abbreviated as oxygen generating substance). And a reaction raw material containing at least a predetermined ratio, and obtained by a combustion synthesis method having an adiabatic flame temperature of 1500 ° C. or higher, and having a relative dielectric constant of 15 or higher.
Further, the Group 4 element constituting the high dielectric ceramic is titanium or zirconium, and the Group 2 element is at least one element selected from strontium, barium and calcium.
In addition, the substance that generates oxygen by the heating is sodium perchlorate.
The high-frequency electronic component of the present invention is a high-frequency electronic component for handling an electrical signal having a frequency of 100 MHz or more, using the high dielectric elastomer composition of the present invention as an electronic component material.

  In the high dielectric elastomer composition of the present invention, since the specific high dielectric ceramic obtained by the combustion synthesis method is blended with the elastomer, a high dielectric elastomer having a relative dielectric constant of 10 to 30 can be easily obtained. In addition, a high frequency electronic component for handling an electrical signal having a frequency of 100 MHz or higher, which uses this high dielectric elastomer composition as an electronic component material, can achieve higher frequency and smaller size.

The high dielectric ceramic that can be used in the present invention is obtained by a combustion synthesis method using a Group 4 metal powder, a Group 2 carbonate, and an oxygen generating material as starting reaction materials.
The metal containing a Group 4 element is preferably a Group 4 element alone, and more preferably a Group 4 A element. Specific examples include titanium (Ti), zirconium (Zr), and hafnium (Hf). Among these, Ti is preferable because ceramics having excellent dielectric properties can be obtained.
Group 4 A elements can be used alone or in combination. Further, elements that can be blended simultaneously with these Group 4 A elements include rutherfordium (Rf), tin (Sn), antimony (Sb), tellurium (Te), lanthanum (La), cerium (Ce), prasedium (Pr), Examples thereof include neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), bismuth (Bi), polonium (Po), and astatine (At).

The shape of the metal containing the Group 4 element is preferably a fine powder, and the specific surface area is 0.01 to ² m ² / g. The range of the specific surface area is preferably 0.03 to 0.6 m ² / g because the combustion wave propagates and is easy to handle. When the specific surface area is less than 0.01 m ² / g, since the contact area between the metal powder that is the heat source and the peroxide that is the oxygen supply source is small, the combustion wave does not propagate and high dielectric ceramics are synthesized. There are cases where it is not possible. Further, metal powders having a specific surface area exceeding 2 m ² / g are not preferable because they are extremely active and difficult to handle.
In the present invention, the specific surface area of the metal powder is a value measured by the BET method.

Even when the average particle diameter of the metal fine powder that can be used for combustion synthesis is the same, a difference in reactivity was recognized when the specific surface area was different. That is, when a metal powder having a specific surface area larger than that of a spherical shape was used, the combustion synthesis reaction proceeded more rapidly. As the shape having a large specific surface area, there are a particle having a plurality of irregularities formed on the surface of a spherical particle, a particle having an irregular shape as a whole, or a combination thereof.
The average particle size that can be used in the present invention is 150 μm or less, preferably 0.1 to 100 μm. If it exceeds 150 μm, mixing with other raw materials becomes insufficient, and combustion waves may not propagate.
An image analysis method is preferable as a method for measuring the average particle diameter of particles having irregularities formed on the surface or an irregular shape.

The element containing a Group 2 element is preferably a Group 2 element alone, more preferably a Group 2 A element. Specific examples include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). Among these, Ca, Sr, and Ba are the above metal powders. Is preferable because ceramics having excellent dielectric properties can be obtained.
Group 2 A elements can be used alone or in combination. Examples of elements that can be blended simultaneously with these Group 2 A elements include Rf, Sn, Sb, Te, La, Ce, Pr, Nd, Pm, Sm, Eu, Bi, Po, and At.

Group 2 A elements are used in the form of carbonates. Examples of carbonates composed of Group 2 A elements include BeCO ₃ , MgCO ₃ , CaCO ₃ , SrCO ₃ , BaCO ₃ , and RaCO ₃ . Of these, CaCO ₃ , SrCO ₃ , and BaCO ₃ are particularly preferable because ceramics having excellent dielectric properties can be obtained.

In the present invention, a substance that generates oxygen by heating is blended with the above starting materials. Substances that generate oxygen by heating include chlorates such as KClO ₃ , NaClO ₃ and NH ₄ ClO ₃ , perchlorates such as KClO ₄ , NaClO ₄ and NH ₄ ClO ₄ , and subchlorine such as NaClO _2. Acid salts, bromates such as KBrO ₃ , nitrates such as KNO ₃ , NaNO ₃ and NH ₄ NO ₃ , iodates such as NaIO ₃ and KIO ₃ , permanganese in KMnO ₄ and NaMnO ₄ .3H ₂ O Acid salts, dichromates such as K ₂ Cr ₂ O ₇ , (NH ₄ ) ₂ Cr ₂ O ₇ , periodates such as NaIO ₄ , metaiodic acids such as HIO ₄ · 2H ₂ O, CrO anhydrous chromate such as _3, nitrite, such as NaNO _3, Ca (ClO) calcium hypochlorite trihydrate salt or the like, such as ₂ · 3H ₂ O and the like.
Among these, perchlorates are preferable, and NaClO ₄ is particularly preferable because it is easy to remove NaCl as a by-product.

In order to obtain excellent dielectric properties, it is only Group 4 metal powder, Group 2 carbonate, and oxygen generating material as the reaction raw material containing at least Group 4 metal powder, Group 2 carbonate, and oxygen generating material. preferable.
The reaction raw materials are blended at a predetermined ratio, respectively. In the combustion synthesis reaction, for example, in the case of barium titanate, the dielectric ceramic is generated according to the following chemical reaction formula. Each reaction raw material is blended in an amount corresponding to the molar mass required for the reaction between the Group 4 metal powder and the Group 2 carbonate, but the oxygen generating substance can be blended in an amount greater than the molar mass necessary for the reaction.

Ti + BaCO ₃ + 0.5NaClO ₄ → BaTiO ₃ + CO ₂ ↑ + 0.5NaCl

The mixing of the reaction raw materials containing at least a Group 4 metal powder, a Group 2 carbonate, and an oxygen generating substance can be used without particular limitation such as mixing using a ball mill or a mortar. The mixture used is preferred.
The mixed powder is put into a crucible and combusted and synthesized. The material of the crucible is preferably non-oxide carbon (C), silicon carbide (SiC), silicon nitride Si ₃ N ₄ or the like. Among these, a carbon (C) material is preferable because it is excellent in heat conduction and shape workability.
As a method for charging the mixed powder into the crucible, there can be used a method in which the mixed powder is spread in the form of a powder bed, compressed after being spread, or a powder that has been pressed and consolidated into a crucible.

Regarding the conditions of the combustion synthesis method, the adiabatic flame temperature of the reaction system is 1500 ° C. or higher. This is because combustion waves propagate at 1500 ° C. or higher.
Combustion synthesis is performed in a chamber, and the atmosphere is preferably a rare gas atmosphere such as helium (He), neon (Ne), argon (Ar), or krypton (Kr). Note that a nitrogen gas, carbon dioxide atmosphere, or the like can be used as long as the dielectric properties of the reaction product are not deteriorated. Also, oxygen gas can be used if the oxygen partial pressure can be controlled.
The method for igniting the mixed powder for initiating combustion synthesis is not particularly limited as long as the metal powder can ignite and generate heat. A method in which a carbon film is ignited to generate heat and used as a heat source and brought into contact with the mixed powder to ignite and generate heat is preferable because it is excellent in handling.

In the combustion synthesis reaction, a chemical reaction proceeds simultaneously and frequently from the ignition portion without requiring external heating, and various non-stoichiometric compounds are synthesized. For this reason, in the present invention, the blending ratio of the Group 4 metal powder, the Group 2 carbonate, and the oxygen generating substance is important.
By carrying out the combustion synthesis reaction at the above-mentioned blending ratio, a high dielectric ceramic having a relative dielectric constant of 15 or more and a dielectric loss tangent of less than 0.01 can be obtained. This high dielectric ceramic can be refined with a mortar and pestle, ball mill, jet mill or other pulverizer to obtain a high dielectric ceramic capable of adjusting the average particle size to 3 μm and the standard deviation (3σ value) within 2.5 μm. . When the standard deviation (3σ) is within this range, the particle size distribution becomes wide and high packing is possible.
The average particle diameter of the high dielectric ceramic powder obtained by the combustion synthesis method and usable in the present invention is 0.01 μm to 100 μm, preferably 0.1 μm to 20 μm, and more preferably 0.1 to 3 μm. When the average particle size is less than 0.01 μm, the particle weight is light, so that it may be scattered at the time of measurement or the volume of the mixer may be increased due to its large volume. On the other hand, if it exceeds 100 μm, there is a risk of causing variation in dielectric characteristics within the elastomer, which is not preferable.

A high dielectric ceramic composition having a relative dielectric constant of 15 or more is obtained by blending a high dielectric ceramic powder produced by a combustion synthesis method and an elastomer.
Natural rubber elastomers and synthetic rubber elastomers can be used in the high dielectric elastomer composition of the present invention.
Natural rubber-based 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 include natural rubber as a raw material and elastomers from synthetic cis-1,4-polyisoprene as a raw material.

  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.

  The said elastomer can be used 1 type or in mixture of 2 or more types. Further, one or two thermoplastic resins can be blended and used within a range that does not impair the elasticity of the elastomer. When one or more kinds selected from natural rubber elastomers and / or synthetic nonpolar elastomers are used as the elastomer of the present invention, a highly dielectric elastomer having excellent electrical insulation can be obtained. In particular, it can be preferably used for applications requiring insulation. Examples of synthetic nonpolar elastomers include ethylene propylene rubber (hereinafter abbreviated as EPDM), ethylene propylene diene rubber, isobutylene rubber, isoprene rubber, silicone rubber and the like. In particular, EPDM and ethylene propylene diene rubber have a very low dielectric loss tangent, and therefore can be preferably used for electronic parts such as antennas and sensor applications.

  The blending ratio of the high dielectric ceramic is an amount that can maintain the relative dielectric constant of the high dielectric elastomer composition at 15 or more and can maintain the moldability that can be obtained for an electronic component such as an antenna. For example, 300 to 2000 parts by weight (phr) of high dielectric ceramic can be blended with 100 parts by weight (phr) of elastomer.

  In the present invention, in order not to impede 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, a silane coupling agent, titanate Coupling agents such as coupling agents and zirconia aluminate coupling agents, (2) In order to improve plating properties for electrode formation, particulate fillers such as talc and calcium pyrophosphate, and (3) heat Antioxidants to further improve stability, (4) Light stabilizers such as ultraviolet absorbers to improve light resistance, and (5) Halogen or phosphorous to further improve flame retardancy. (6) Impact resistance imparting agent to improve impact resistance, (7) Lubricant, rocking property improver (solid lubricant, liquid lubrication to improve lubricity Agent), (8) coloring For this purpose, colorants such as dyes and pigments, (9) plasticizers for adjusting physical properties, crosslinking agents such as sulfur and peroxides, and (10) vulcanization accelerators for proceeding with vulcanization are blended. be able to.

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

  The method for producing the highly dielectric elastomer composition of the present invention is not particularly limited, and various mixed molding methods can be used. For example, a method of producing by kneading with a twin screw extruder is preferably used. Immediately, a molded product may be obtained by injection molding, extrusion molding, or the like, or a molding material such as a pellet, rod-shaped material, or plate-shaped material may be used.

  The high dielectric elastomer composition of the present invention is excellent in dielectric properties because it contains a high dielectric ceramic produced by a combustion synthesis method. Therefore, a high-frequency electronic component that operates at 100 MHz using this elastomer composition can further increase the signal propagation speed in the high-frequency band, and can reduce the size of the electronic component due to the wavelength shortening effect. Therefore, it is suitable for a patch antenna used for a mobile phone, a cordless phone, an RFID, etc., a lens antenna such as a radio telescope, a millimeter wave radar, and the like.

Reference Synthesis Example 1 to Reference Synthesis Example 6
High dielectric ceramics were synthesized by the following method.
A mixed powder was obtained by mixing Group 4 metal powders, Group 2 carbonates, and oxygen-generating substances having different specific surface areas shown in Table 1 for 5 hours at a molar ratio shown in Table 1 using a ball mill. A carbon crucible was installed in the chamber in the synthesizer, the mixed powder (100 g) was spread in the carbon crucible, and the ignition carbon film was brought into contact with a part of the mixed powder to close the chamber. After reducing the residual oxygen in the chamber using a vacuum pump, argon (Ar) gas was sealed, and the internal pressure of the chamber was set to 0.1 MPa.

Combustion waves propagated in all the compositions of Reference Synthesis Examples 1 to 6, and synthetic powder and by-product (NaCl) were obtained by the combustion synthesis method. The synthetic powder was pulverized using an alumina mortar to obtain an unwashed high dielectric ceramic powder having an average particle size of 2 μm.
The obtained unwashed high dielectric ceramic powder was sufficiently washed with water, and NaCl adhered to the powder was removed to obtain a high dielectric ceramic.
The crystal phase of the obtained high dielectric ceramic powder was identified using an X-ray diffractometer. The results are shown in Table 2 as the ceramic composition.
The relative dielectric constant and dielectric loss tangent were measured by the following methods.
1% by weight of a molding binder (polyvinyl butyral resin) was added to and mixed with the obtained high dielectric ceramic powder. Next, the mixed powder was put into a 10 mm × 80 mm mold, and a pressure of 1.5 ton / cm ² was applied to obtain a green body (10 mm × 90 mm × 3 mm). The green body was held at 600 ° C. for 1 hour to remove organic components, and then fired at 1300 ° C. for 3 hours. The obtained sintered body was 70 mm × l. 5 mm × l. The sample was processed into a 5 mm test piece, and the dielectric constant and dielectric loss tangent were measured in the 1, 3, and 5 GHz frequency bands using the cavity resonator method. Here, the relative dielectric constant and the dielectric loss tangent are values at 25 ° C. The results are shown in Table 2.

Examples 1 to 6
Table 3 shows EPDM (Mitsui Chemicals Co., Ltd .: EPT-3095), ceramic powder synthesized by combustion synthesis, carbon black (manufactured by Tokai Carbon Co., Ltd .: Seast S), vulcanization accelerator, processing aid, and the like. After mixing at a blending ratio and kneading with a pressure kneader, a molded body of 80 mm × 80 mm × 1.5 mm was obtained by heat compression molding. The vulcanization conditions are each 170 ° C. × 20 minutes.
The process oil is PW-380 manufactured by Idemitsu Kosan Co., Ltd., the zinc oxide is META-Z L-40 manufactured by Inoue Coal Industry, the stearic acid is Lunac S-30 manufactured by Kao Corporation, and the anti-aging agent is Seiko. Non-flex RD-G manufactured by Kagaku Co., Soccinol M manufactured by Sumitomo Chemical Co., Ltd. was used as the vulcanization accelerator, and Kayak Mill D40 manufactured by Kayaku Akzo Co., Ltd. was used as the peroxide crosslinking agent.
From the obtained molded body, 1.5 mm × l. A strip-shaped test piece of 5 mm × 80 mm was processed, and dielectric properties (relative permittivity and dielectric loss tangent) were measured at 1 GHz band and 5 GHz band by a cavity resonator method. Table 3 shows the measurement results. In all of the examples, the relative dielectric constant is 10 or more and the dielectric loss tangent is 0.007 or less.

Comparative Example 1 and Comparative Example 2
Dielectric ceramic powder (manufactured by Kyoritsu Materials Co., Ltd .: ST-NAS) is 600 parts by weight in Comparative Example 1, 900 parts by weight in Comparative Example 2, and 100 parts by weight with respect to 100 parts by weight of EPDM (Mitsui Chemicals Co., Ltd .: EPT-3095). Each compounding agent was mixed at the blending ratio shown in Table 3, and after kneading with a pressure kneader, a compact of 80 mm × 80 mm × 1.5 mm was obtained by heat compression molding. The vulcanization conditions are each 170 ° C. × 20 minutes.
From the obtained molded body, 1.5 mm × l. A strip-shaped test piece of 5 mm × 80 mm was processed, and dielectric properties (relative permittivity and dielectric loss tangent) were measured at 1 GHz band and 5 GHz band by a cavity resonator method. Table 3 shows the measurement results. Compared with Example 1 and Example 2 in which the combustion synthetic powder was blended, Comparative Example 1 and Comparative Example 2 had a lower relative dielectric constant despite the same blending amount of the dielectric ceramic powder. .

Comparative Example 3 and Comparative Example 4
With respect to 100 parts by weight of EPDM (Mitsui Chemicals Co., Ltd .: EPT-3095), dielectric ceramic powder (manufactured by Kyoritsu Materials Co., Ltd .: ST-NAS) is 1200 parts by weight in Comparative Example 3, 1500 parts by weight in Comparative Example 4, and other Each compounding agent was mixed in the mixing ratio shown in Table 3, and kneading was attempted with a pressure kneader. However, since the amount of the dielectric ceramic powder was too large, it could not be homogeneously kneaded and the dielectric properties were measured. Therefore, a molded product for the purpose was not obtained.

  Since the high dielectric elastomer composition of the present invention is blended with high dielectric ceramics by a combustion synthesis method, it can be easily filled. Therefore, a highly dielectric elastomer composition having excellent dielectric properties can be obtained, and can be suitably used for patch antennas used for mobile phones, cordless phones, RFIDs, etc., lens antennas such as radio telescopes and millimeter wave radars, and the like.

Claims (5)

A high dielectric elastomer composition obtained by blending a high dielectric ceramic with an elastomer,
The high dielectric ceramic includes at least a metal powder containing a Group 4 element having a specific surface area of 0.01 to ² m ² / g, a carbonate of an element containing a Group 2 element, and a substance that generates oxygen by heating. A high dielectric elastomer composition obtained by a combustion synthesis method in which reaction raw materials are blended at a predetermined ratio, adiabatic flame temperature is 1500 ° C. or higher, and a relative dielectric constant is 15 or higher.   2. The highly dielectric elastomer composition according to claim 1, wherein the group 4 element is titanium.   The high dielectric elastomer composition according to claim 1 or 2, wherein the Group 2 element is at least one element selected from strontium, barium and calcium.   4. The high dielectric elastomer composition according to claim 1, wherein the substance that generates oxygen by heating is sodium perchlorate. A high-frequency electronic component for handling an electrical signal having a frequency of 100 MHz or more, using a high dielectric elastomer composition as an electronic component material,
The high dielectric elastomer composition according to any one of claims 1 to 4, wherein the high dielectric elastomer composition is a high frequency electronic component.