JP2008019382A - Resin composition for electronic parts and electronic parts - Google Patents

Abstract

The present invention provides an electronic component having isotropic dielectric characteristics that sufficiently suppresses changes in dielectric characteristics with respect to environmental changes, and a resin composition for electronic components for producing the electronic component.
A resin composition for electronic parts comprising polybutylene terephthalate, a carboxylic acid-modified thermoplastic elastomer, and a titanic acid-based inorganic compound, and an electronic part formed by molding the resin composition .
[Selection figure] None

Description

  The present invention relates to a resin composition for electronic parts and an electronic part formed by molding the resin composition. Specifically, the present invention relates to an electronic component suitable for high frequency applications and excellent in environmental resistance, particularly an antenna component, and a resin composition for producing the electronic component.

  Conventionally, as a resin composition suitable for an electronic component such as an antenna component, a material having a low dielectric constant and dielectric loss and a small change in dielectric constant and dielectric loss with respect to environmental changes such as temperature and humidity has been demanded. Yes.

  For example, a resin dielectric antenna made of a composite material of synthetic resin and dielectric ceramics, which is made of a material capable of injection molding exhibiting specific dielectric properties has been reported (Patent Document 1). However, an antenna having a sufficiently small change in dielectric characteristics with respect to the environmental change cannot be obtained, and the dielectric loss is increased particularly in a high temperature and high humidity environment. When the dielectric loss increases, it is difficult to transmit radio waves and it is difficult to use the antenna component.

  Further, for example, a resin composition comprising a synthetic resin matrix containing a fibrous material of a specific alkaline earth metal titanate, and a resin composition for molding an antenna substrate material of a high-frequency communication device exhibiting specific dielectric properties The thing is reported (patent document 2). However, it is still difficult to obtain an antenna substrate having a sufficiently small change in dielectric characteristics with respect to environmental changes, and the dielectric loss tends to increase particularly in a high temperature and high humidity environment. In addition, since the obtained antenna substrate has dielectric anisotropy, design restrictions occur, the design period increases due to cut-and-try, and the antenna characteristics tend to vary during mass production.

For example, an impact-resistant resin composition in which an inorganic filler and an elastomer member are finely dispersed in a matrix resin has been reported (Patent Document 3). However, it is still impossible to obtain a molded product having a sufficiently small change in dielectric characteristics with respect to environmental changes, and the dielectric loss tends to increase particularly in a high temperature and high humidity environment.
Japanese Patent Laid-Open No. 2005-94068 Japanese Patent No. 2873541 JP 2003-147 211 A

  The present invention provides an electronic component (for example, an antenna component) that has an isotropic dielectric property, sufficiently suppressing a change in dielectric property with respect to an environmental change, and a resin composition for an electronic component for producing the electronic component. The purpose is to provide.

  The present invention comprises a polybutylene terephthalate, a carboxylic acid-modified thermoplastic elastomer, and a titanic acid-based inorganic compound, a resin composition for electronic components, and an electronic component formed by molding the resin composition, In particular, it relates to antenna parts.

The electronic component comprising the resin composition of the present invention can sufficiently suppress changes in dielectric characteristics with respect to environmental changes, and can effectively suppress the increase in dielectric loss over time particularly in a high temperature and high humidity environment.
In the present invention, the electronic component can be manufactured by an injection molding method or the like, and has an isotropic dielectric property, so that the degree of freedom in designing the electronic component and the mass productivity are excellent.
In the present invention, the electronic component is also excellent in flame retardancy.

  The resin composition for electronic parts according to the present invention (hereinafter sometimes simply referred to as “resin composition”) contains at least a matrix resin, an elastomer, and a titanic acid inorganic compound.

  The matrix resin constituting the resin composition is polybutylene terephthalate (hereinafter referred to as “PBT”), and if desired, polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polystyrene (PS), syndiotactic. Other resins such as polystyrene (SPS), liquid crystal polymer (LCP), and Teflon (PTFE) may be included.

The molecular weight of the PBT is not particularly limited as long as the object of the present invention is achieved, for example, melt volume flow rate (MVR) is 5~60cm ³ / 10min., Is particularly preferred 20 to 40 cm ³ / 10min. Things .

  In this specification, MVR uses a value measured at a temperature of 250 ° C. and a load of 2.16 kg in accordance with ISO1133.

Commercially available PBT can be used, for example, Novaduran ^R 5010N5, 5010N6, 5010R3, 5010R5, 5010R5L, 5010CR2 (above, manufactured by Mitsubishi Engineering Plastics Co., Ltd.), Juranex ^R 2000, 2002, 2016, CN7000, CRN7000 (manufactured by Wintech Polymer Co., Ltd.) and the like.

  The content of the matrix resin is usually from 50 to 95% by volume, particularly preferably from 60 to 90% by volume, based on the total amount of the resin composition.

  The content of PBT with respect to the matrix resin is not particularly limited as long as the object of the present invention is achieved, but it is usually 50% by volume or more, particularly 70 to 100% by volume, and preferably 80 to 100% by volume. If the PBT content is too low, the compatibility, heat resistance, and mechanical strength of PBT and other matrices will be problems, and the dielectric properties will change significantly with environmental changes, so it will not withstand use as an electronic component. .

  Elastomers are polymers that exhibit rubber elasticity at room temperature, and generally include natural rubber and synthetic rubber. In the present invention, a synthetic rubber-based elastomer modified with a carboxylic acid is used. That is, an elastomer having a carboxyl group introduced is used. Thereby, the change of the dielectric property with respect to the environmental change can be suppressed. Details of the mechanism are not clear, but by using a carboxylic acid-modified elastomer, adhesion between the titanic acid-based inorganic compound and the matrix resin, which will be described later, is promoted. It can be prevented, and it is considered that the change of the dielectric property with respect to the environmental change is suppressed.

Carboxylic acid-modified elastomer is typically an acid number 0.5~10CH ₃ ONamg / g, in particular using those 1.0~2.0CH ₃ ONamg / g. If the acid value is too large, the viscosity increases during the molding process, and the processability deteriorates. Moreover, the dielectric properties after the environmental test are deteriorated. If the acid value is too small, the compatibility with PBT is poor, and defects during molding, strength reduction, etc. are likely to occur. Moreover, the change of the dielectric property with respect to the environmental change cannot be sufficiently suppressed.
The acid value is a value measured by a titration method.

  The carboxylic acid-modified elastomer preferably has a carboxyl group introduced at the end of the elastomer molecule. An elastomer of a type in which a carboxyl group is graft-polymerized generally has a large acid value, and this tends to increase dielectric characteristics (particularly, dielectric loss tangent), which is not preferable.

  The carboxylic acid-modified elastomer can be produced by any method as long as a carboxyl group can be introduced into the elastomer molecule. For example, (1) a method in which a raw material elastomer is dissolved in a solvent such as toluene and then an unsaturated carboxylic acid is added and polymerized, and (2) a raw material elastomer, a peroxide, and an unsaturated carboxylic acid are charged into an extruder. Examples thereof include a graft reaction method, and (3) a method of adding an unsaturated carboxylic acid to a raw material elastomer in an extruder. In particular, according to the method (3), an elastomer whose terminal is modified with a carboxylic acid can be obtained effectively. In the reactions (1) to (3), a radical initiator is used as necessary.

  The raw material elastomer is not particularly limited as long as a carboxyl group can be introduced. For example, styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS), Examples include styrene-based elastomers such as styrene-ethylene-propylene-styrene block copolymer (SEPS) and styrene-butadiene-butylene-styrene (SBBS); urethane elastomers; olefin elastomers; and polyester elastomers. Among the raw material elastomers, it is preferable to use a styrene-based elastomer containing a styrene monomer as a monomer component from the viewpoint of the strength of electronic parts and the viewpoint of dielectric characteristics. Styrenic elastomers, particularly SEBS, may contain 10 to 60% by weight, particularly 15 to 50% by weight, of the styrene monomer component, based on the total monomers constituting the elastomer, from the viewpoint of further improving the strength of electronic components and dielectric properties. preferable. Urethane elastomers, olefin elastomers, and polyester elastomers may be used in combination with styrene elastomers as long as they do not affect the dielectric properties.

  The number average molecular weight of the raw material elastomer is not particularly limited as long as the object of the present invention is achieved, and is preferably 20,000 to 300,000, particularly preferably 30,000 to 250,000, from the viewpoint of moldability and strength of electronic parts.

  In this specification, the number average molecular weight is a value measured by GPC (manufactured by Shimadzu Corporation).

  The raw material elastomer is available as a commercial product. For example, Tuftec H1031, H1043, H1051 manufactured by Asahi Kasei Corporation and the like can be mentioned.

  The unsaturated carboxylic acid is not particularly limited as long as it can introduce a carboxyl group into the raw material elastomer. For example, unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; and unsaturated dicarboxylic acids such as maleic anhydride, itaconic anhydride, maleic acid, fumaric acid, citraconic acid, phthalic acid, and itaconic acid. .

  The unsaturated carboxylic acid may be used in such an amount that the carboxylic acid-modified elastomer has the above acid value, and is usually 0.01 to 2% by weight, particularly 0.05 to 1.5% by weight, based on the raw material elastomer. Is appropriate.

  The carboxylic acid-modified elastomer can be obtained as a commercial product. For example, N502, M1911, M1913 Asahi Kasei Co., Ltd. (Asahi Kasei Co., Ltd. product) etc. are mentioned.

  The content of the carboxylic acid-modified elastomer is usually 5 to 50% by volume, particularly 5 to 40% by volume, based on the total amount of the resin composition.

  The titanic acid inorganic compound is not particularly limited as long as it is a metal titanate, and from the viewpoint of availability and cost, for example, from the group consisting of barium titanate, calcium titanate, strontium titanate, and magnesium titanate. At least one selected inorganic compound is preferably used. More preferably at least strontium titanate is used, most preferably strontium titanate is used alone. This is because strontium titanate can more effectively suppress changes in dielectric properties with respect to environmental changes, and the dielectric constant can be more efficiently controlled by the content. If other inorganic compounds such as magnesium oxide, calcium carbonate, titanium oxide, etc. are used instead of titanic acid-based inorganic compounds, the dielectric properties change significantly with respect to environmental changes, so they cannot be used as electronic components. .

  The titanic acid-based inorganic compound is preferably a surface-treated one. By including the surface-treated titanic acid-based inorganic compound, it is possible to more effectively suppress changes in dielectric properties with respect to environmental changes by suppressing water absorption. Although water molecules exist on the surface of the titanic acid-based inorganic compound, the water molecules can be removed by the surface treatment, so that the water molecules remaining at the interface between the inorganic compound and the matrix resin in the electronic component can be effectively reduced. As a result, the adhesion between the inorganic compound and the matrix resin is further promoted, so that water molecules can be prevented from entering between them, and the change in dielectric properties with respect to environmental changes can be more effectively suppressed. It is done. The surface treatment is achieved by heating while mixing the titanic acid inorganic compound and the surface treatment agent. As the surface treatment agent, those known in the field of inorganic compounds contained in electronic components are used, and examples thereof include so-called silane coupling agents, titanate coupling agents, aluminum coupling agents, fatty acids and the like. A titanate coupling agent is preferably used. The amount of the surface treatment agent used is not particularly limited, and usually 0.1 to 2% by weight with respect to the titanic acid inorganic compound is preferable.

  The titanic acid-based inorganic compound is more preferably one that has been surface-treated as described above and then washed with an organic solvent. By including such a surface-treated and washed-treated titanic acid-based inorganic compound, it is possible to more effectively suppress the change in dielectric properties, particularly the dielectric loss tangent to the environmental change. By including such a titanic acid-based inorganic compound, the adhesion between the inorganic compound and the matrix resin is further promoted, so that intrusion of water molecules from between them can be prevented, and the dielectric against environmental changes can be prevented. It is considered that the characteristics can be more effectively suppressed. The cleaning treatment is achieved by dispersing the surface-treated titanic acid inorganic compound in an organic solvent, filtering, and drying. The organic solvent is not particularly limited as long as it is a solvent capable of dissolving the surface treating agent, and for example, general solvents such as methanol, ethanol, acetone, isopropyl alcohol, hexane, toluene, xylene and the like can be used.

As the titanic acid-based inorganic compound, those having a particle form are usually used.
The average particle diameter of the titanic acid-based inorganic compound is not particularly limited as long as the object of the present invention is achieved, and is usually 0.01 to 10 μm, and particularly preferably 0.1 to 3 μm.

  In the present specification, the average particle size is a value measured by LA-920 (manufactured by Horiba, Ltd.).

  The aspect ratio of the titanic acid-based inorganic compound is preferably 1 to 3, particularly 1 to 2, from the viewpoint of further improving the isotropic property of dielectric properties.

The aspect ratio is a ratio of the minimum length to the maximum length (maximum length / minimum length) in the cross section of the titanic acid-based inorganic compound.
The aspect ratio can be obtained by taking an electron micrograph (magnification of about 1000 to 2000 times) of the titanic acid-based inorganic compound, calculating the aspect ratio of arbitrary 50 to 100 particles from the photograph, and averaging. .

  A titanic acid type inorganic compound is easily available as a commercial item. In particular, as specific examples of commercially available titanic acid-based inorganic compounds that are not surface-treated, for example, BT, CT, ST (manufactured by Kyoritsu Material Co., Ltd.), BT, ST, BTZ (manufactured by Fuji Chemical Co., Ltd.), etc. Is mentioned.

  The content of the titanic acid-based inorganic compound is preferably 1 to 45% by volume with respect to the total amount of the resin composition, and particularly preferably 20 to 45% by volume in order to increase the dielectric constant.

  In addition to the matrix resin, elastomer and titanic acid inorganic compound described above, the resin composition includes so-called flame retardants, flame retardant aids, antioxidants, hydrolysis inhibitors, lubricants, which are known in the field of electronic component raw materials. Additives such as reinforcing agents (glass fiber, wollastonite, zonolite, sepiolite, mica, potassium titanate whisker, layered silicate, organically treated bentonite) may be contained within a range that does not adversely affect the dielectric properties. .

The electronic component can be manufactured by various methods using the resin composition.
For example, a matrix resin, an elastomer, a titanic acid inorganic compound, and other additives are melt-kneaded to obtain resin composition pellets. Next, the pellet is formed into a predetermined shape by an injection molding method, an extrusion molding method, a transfer molding method, or the like, and cooled to obtain an electronic component.

  The electronic component of the present invention can control the dielectric constant by adjusting the content of the titanic acid inorganic compound. For example, increasing the content increases the dielectric constant, while decreasing it decreases the dielectric constant. Specifically, by setting the titanic acid inorganic compound content in the above range, the dielectric constant can be set to 4 to 20, particularly 8 to 15. In electronic parts, particularly those for high frequency applications, the larger the dielectric constant, the more advantageous is the miniaturization of electronic products such as antennas due to the wavelength shortening effect.

  Further, the electronic component of the present invention can set the dielectric loss tangent to be relatively low, and the change of the dielectric loss tangent with respect to the environmental change is small. For example, the dielectric loss tangent can be ensured to be less than 0.01 even when stored for a long time in a high temperature and high humidity environment. As a result, it is possible to effectively suppress transmission loss of radio waves in electronic components, particularly antenna components, over a long period of time.

(Titanate inorganic compound A)
Henschel capable of heating strontium titanate (manufactured by Kyoritsu Material Co., Ltd .; ST) and 0.5 wt% titanate coupling agent (manufactured by Ajinomoto Finetech Co., Ltd .; KR) with respect to the strontium titanate The mixture was put into a mixer, mixed while being heated and subjected to surface treatment to obtain titanic acid inorganic compound A.

(Titanate inorganic compound B)
After titanic acid-based inorganic compound A was washed with an organic solvent (methanol, ethanol, etc.), it was filtered and dried to obtain titanic acid-based inorganic compound B.

(Titanate inorganic compound C)
Strontium titanate (manufactured by Kyoritsu Material Co., Ltd .; ST, average particle size 0.9 μm) was used as it was.

(Example 1)
50% by volume of flame retardant non-reinforced polybutylene terephthalate (PBT: manufactured by Mitsubishi Engineering Plastics Co., Ltd .; Novaduran ^R 5010N5) dried with hot air at 120 ° C. for 8 hours and carboxylic acid modified SEBS (Asahi Kasei Co., Ltd.) ); N502) was previously mixed with 20% by volume based on the entire resin composition.
The cylinder mixture was 250 ° C. and the rotation speed was 200 rpm while pulling the obtained mixture and 30% by volume of the titanic acid-based inorganic compound A with respect to the whole resin composition using a twin screw extruder with a 30 mm screw diameter. The mixture was melt-kneaded at a discharge rate of 25 kg / h. The strand discharged from the die was passed through cooling water and cut to prepare resin composition pellets.

(Example 2)
A pellet of the resin composition was prepared in the same manner as in Example 1 except that titanic acid inorganic compound B was used instead of titanic acid inorganic compound A.

(Comparative Example 1)
65% by volume of flame retardant non-reinforced polybutylene terephthalate (PBT: manufactured by Mitsubishi Engineering Plastics Co., Ltd .; Novaduran ^R 5010N5) dried with hot air at 120 ° C. for 8 hours, and titanic acid inorganic compound C as resin 35% by volume with respect to the entire composition was melt-kneaded at a cylinder temperature of 250 ° C., a rotational speed of 200 rpm, and a discharge rate of 25 kg / h while being evacuated using a twin screw extruder with a screw diameter of 30 mm. The strand discharged from the die was passed through cooling water and cut to prepare resin composition pellets.

(Comparative Example 2)
Pellets of the resin composition were prepared in the same manner as in Comparative Example 1 except that titanic acid inorganic compound A was used instead of titanic acid inorganic compound C.

(Comparative Example 3)
Pellets of the resin composition were prepared in the same manner as in Comparative Example 1 except that titanic acid inorganic compound B was used instead of titanic acid inorganic compound C.

(Comparative Example 4)
Pellets of the resin composition were prepared in the same manner as in Example 1 except that SEBS (manufactured by Asahi Kasei Corporation; H1041, carboxylic acid unmodified) was used instead of carboxylic acid-modified SEBS.

(Comparative Example 5)
Implemented except that SEBS (manufactured by Asahi Kasei Co., Ltd .; H1041, unmodified carboxylic acid) was used instead of carboxylic acid-modified SEBS and titanic acid-based inorganic compound B was used instead of titanic acid-based inorganic compound A In the same manner as in Example 1, pellets of the resin composition were prepared.

(Evaluation)
Evaluation was performed using each pellet obtained in Examples / Comparative Examples.
-Change rate of dielectric constant and dielectric loss tangent From the pellet, a flat plate of about 89 mm x 89 mm x thickness 2 mm was molded at a resin temperature of 260 ° C using an injection molding machine with a clamping force of 40 t. This flat plate was cut in an arbitrary direction to prepare a test piece of 85 mm length × 1.7 mm × 1.7 mm. The dielectric constant and dielectric loss tangent of the test piece at 3 GHz were measured using a cavity resonator perturbation method dielectric constant measuring apparatus (manufactured by Kanto Electronics Co., Ltd.) and a network analyzer (8722ES; manufactured by Agilent Technologies). Value. Next, after storing in a constant temperature and humidity chamber at a temperature of 85 ° C. and a humidity of 85% for 200 hours, the dielectric constant and dielectric loss tangent at 3 GHz are measured again to obtain Δε and Δtan, and the change from the initial value The rate was calculated.
The rate of change of the dielectric constant is 3% or less, which is practically acceptable, preferably 2.5% or less, and most preferably 2.4% or less.
The rate of change of the dielectric loss tangent is 15% or less in a range where there is no practical problem, preferably 10% or less, more preferably 5% or less, and most preferably 1% or less.

-Dielectric anisotropy A flat plate was formed from pellets by the same method as the evaluation method of the change rate of the dielectric constant and the dielectric loss tangent. As shown in FIG. 1, this flat plate is cut along a flow direction (MD direction) during injection molding and a direction perpendicular to the flow direction (TD direction), and four tests are performed in each direction. A piece (85 mm long × 1.7 mm × 1.7 mm) was prepared. The dielectric constant at 3 GHz of all the test pieces was measured using a cavity resonator perturbation method dielectric constant measuring device (manufactured by Kanto Electronics Co., Ltd.) and a network analyzer (8722ES; manufactured by Agilent Technologies), The isotropic index “average dielectric constant of the test piece obtained along the MD direction / average dielectric constant of the test piece obtained along the TD direction” was determined.
The dielectric anisotropy index is in the range of 0.9 to 1.1 in practical use, preferably 0.95 to 1.05, and most preferably 0.97 to 1.03.

When Examples 1 and 2 are compared with Comparative Examples 1 to 5, it can be seen that Examples 1 and 2 have the smallest change rate of dielectric loss, which is an important characteristic for transmission loss of the antenna, and are most excellent.
From the comparison between Examples 1 and 2 and Comparative Examples 4 and 5, improvement in the change rate of dielectric constant and dielectric loss tangent is recognized by introducing a carboxylic acid-modified elastomer.
From the comparison between Comparative Example 1 and Comparative Example 2, it is recognized that the change in dielectric constant and dielectric loss tangent is improved by subjecting the titanic acid inorganic compound to surface treatment.
From the comparison between Example 1 and Example 2, the comparison between Comparative Example 2 and Comparative Example 3, and the comparison between Comparative Example 4 and Comparative Example 5, not only the surface treatment for the titanic acid inorganic compound but also the cleaning. By performing the treatment, improvement in the change rate of the dielectric constant and the dielectric loss tangent is recognized.
In particular, when Example 1 is compared with Example 2, not only the surface treatment but also the cleaning treatment is performed on the titanic acid-based inorganic compound, and the carboxylic acid-modified elastomer is introduced. It can be seen that specifically good characteristics can be obtained in which the dielectric constant change rate is the smallest and the dielectric loss does not change at all.

Dielectric anisotropy is a phenomenon in which the dielectric characteristics vary depending on the direction of the applied electric field. If this anisotropy is large, the difference between the simulation results and the actual antenna characteristics results, and the resin flow during molding There is a concern that the antenna characteristics may vary due to variations in the flow of the molded product due to the influence of the above.
The resin compositions of Examples 1 and 2 have a dielectric anisotropy index of approximately 1, have isotropic dielectric properties, and exhibit very good dielectric properties.

The electronic component of the present invention is effective when applied to applications that require stable dielectric characteristics against environmental changes. In particular, excellent performance is exhibited in electronic components used in a high frequency region such as a coil, a filter, a SAW filter, a sensor, and an antenna whose change in dielectric characteristics affects the performance.
In particular, the antenna component of the present invention is useful as any member as long as it is a resin member in various types of antennas. Specific examples of the antenna component resin composition and antenna component to which the antenna component of the present invention can be applied include a monoconical antenna, a lens antenna, a horn antenna, and a loop antenna.
The antenna component of the present invention is most effective when applied to high-frequency applications that have a large adverse effect due to water. The antenna component has a significant transmission loss due to water absorption in the high frequency region, and the transmission characteristics are greatly deteriorated. However, the antenna component of the present invention can effectively suppress the change of the dielectric property with respect to the environmental change. This is because excellent transmission characteristics can be effectively exhibited.

The schematic for demonstrating the test piece for evaluation created in the Example is shown.

Claims (6)

  A resin composition for electronic parts, comprising polybutylene terephthalate, a carboxylic acid-modified thermoplastic elastomer, and a titanic acid-based inorganic compound.   The titanate-based inorganic compound is at least one inorganic compound selected from the group consisting of barium titanate, calcium titanate, strontium titanate, and magnesium titanate, and the content of the titanate-based inorganic compound is a resin composition The resin composition for electronic components according to claim 1, wherein the content is 1 to 45% by volume based on the total amount of the object.   The electronic resin composition according to claim 1 or 2, wherein the titanic acid-based inorganic compound is strontium titanate.   The electronic resin composition according to any one of claims 1 to 3, wherein the titanate inorganic compound is surface-treated with a titanate coupling agent and then washed with an organic solvent.   The electronic component formed by shape | molding the resin composition for electronic components in any one of Claims 1-4.   An antenna component formed by molding the resin composition for electronic components according to claim 1.

Images