JP2022178754A - High-frequency dielectric - Google Patents

Abstract

To provide a high-frequency dielectric which has both good high-frequency characteristics and mechanical characteristics, and is advantageous in cost.SOLUTION: There are provided a high-frequency dielectric that contains a thermoplastic resin and inorganic substance powder in a mass ratio of 50:50 to 10:90, wherein the thermoplastic resin is a polyolefin-based resin, and the inorganic substance powder is heavy calcium carbonate powder, and has a relative dielectric constant ε of 5 or less and a dielectric loss tangent tanδ of 1×10-3 or less, at a frequency of 1 GHz or more and a temperature of 25°C; and a method for manufacturing a high-frequency dielectric which includes steps of extrusion-molding a sheet-like object containing the thermoplastic resin and the inorganic substance powder, and uniaxially or biaxially stretching the sheet-like object.SELECTED DRAWING: None

Description

The present invention relates to high frequency dielectrics. More specifically, the present invention relates to a high-frequency dielectric material in which a thermoplastic resin is highly filled with heavy calcium carbonate and has both excellent high-frequency characteristics and mechanical characteristics.

2. Description of the Related Art In recent years, the frequency of semiconductor devices mounted on electronic devices has been increasing. From the viewpoint of preventing power loss due to an increase in dielectric loss accompanying higher frequencies, a dielectric device with a low dielectric loss tangent is required. Dielectric devices for high frequencies are required to have good mechanical and thermal properties in addition to low dielectric loss tangent. Also, it is desirable to adjust the dielectric constant to an appropriate value according to the application and size of the device. Conventionally, in the field of dielectric devices such as resonators, filters, antennas, circuit boards, and laminated circuit element boards using high-frequency dielectrics, thermoplastic Alternatively, a material obtained by adding inorganic substance powder such as magnesium oxide or ceramic powder to thermosetting resin is used (for example, Patent Documents 1 to 4, Non-Patent Document 1).

JP 2014-24916 A Japanese Patent No. 2015-40296 JP 2009-249673 A Japanese Patent Application Laid-Open No. 2001-220514

Imai, Shatter No. 58, p22-27 (2015)

Magnesium oxide or the like added as an inorganic powder in Patent Document 1 has a problem in dispersing well in general-purpose thermoplastic resins such as polypropylene-based resins and polyethylene-based resins. Such a high-frequency dielectric material has a problem that it cannot withstand practical use because of its poor dispersion and large variations in mechanical properties such as tensile strength and elongation and high-frequency properties. Inorganic powders are blended for the purpose of enhancing mechanical properties such as elastic modulus of resins, but poor dispersion in resins may cause breakage and even lower mechanical properties.

In the inventions described in Patent Documents 2 and 3, expensive inorganic substance powder such as coated fine particles is essential, so the high-frequency dielectric is inevitably costly. In the resin composition for electronic parts of Patent Document 4, cost reduction is attempted by adding specific calcium carbonate. However, in the invention described in Patent Document 4, it is essential to use high-purity calcium carbonate with a purity of 99.5% or more, particularly high-purity precipitated calcium carbonate, and significant cost reduction cannot be achieved. In addition, depending on the type of calcium carbonate or thermoplastic resin, it is difficult to adjust the high-frequency characteristics, and even in the examples of Patent Document 4, the addition of high-purity calcium carbonate increases both the dielectric loss tangent and the dielectric constant.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-frequency dielectric that has both good high-frequency characteristics and mechanical characteristics and is advantageous in terms of cost.

As a result of intensive studies, the inventors of the present invention have found that by filling a general-purpose thermoplastic resin such as a polyolefin resin with a high amount of heavy calcium carbonate powder as an inorganic substance powder, it is possible to achieve both good high-frequency characteristics and mechanical characteristics and reduce costs. Also, if the relative permittivity and dielectric loss tangent at frequencies of 1 GHz or higher are below specific values, high frequency dielectrics can be designed for various uses and sizes. have arrived at the present invention.

That is, the present invention for solving the above problems is a high-frequency dielectric containing a thermoplastic resin and an inorganic powder in a mass ratio of 50:50 to 10:90, wherein the thermoplastic resin is a polyolefin resin. wherein the inorganic substance powder is heavy calcium carbonate powder, and has a dielectric constant ε of 5 or less and a dielectric loss tangent tan δ of 1×10 ⁻³ or less at a frequency of 1 GHz or higher and at a temperature of 25° C. It is a high frequency dielectric.

In one embodiment of the resin composition of the present invention, the thermoplastic resin is a polypropylene-based resin and/or a polyethylene-based resin, a high-frequency dielectric.

In one embodiment of the resin composition of the present invention, a high frequency dielectric material is presented wherein the ground calcium carbonate powder is a surface-treated ground calcium carbonate powder.

In one embodiment of the resin composition of the present invention, the heavy calcium carbonate powder is a high-frequency dielectric material having an average particle size of 0.7 μm or more and 7.0 μm or less measured by an air permeation method according to JIS M-8511. is shown.

In one embodiment of the resin composition of the present invention, the heavy calcium carbonate powder has a BET specific surface area of 0.1 m ² /g or more and 10.0 m ² /g or less, and a circularity of 0.50 or more and 0.50 m 2 /g or more. A high frequency dielectric is shown that is 95 or less.

In one embodiment of the resin composition of the present invention, the heavy calcium carbonate powder contains at least two groups of particles having different average particle sizes, and the at least two groups of particles having different average particle sizes , a primary calcium carbonate particle group having an average particle size of 0.7 μm or more and less than 2.2 μm by an air permeation method according to JIS M-8511, and an average particle size of 2.0 μm by an air permeation method according to JIS M-8511. and a second calcium carbonate particle group of 2 μm or more and 7.0 μm or less in a mass ratio of 1:1 to 5:1.

In one embodiment of the resin composition of the present invention, when the average particle size of the first calcium carbonate particle group is a and the average particle size of the second calcium carbonate particle group is b, the a/b ratio is High-frequency dielectrics are shown having a σ less than or equal to 0.85.

In one embodiment of the resin composition of the present invention, a high-frequency dielectric having a porosity of 5% or more and 35% or less is indicated.

In one embodiment of the resin composition of the present invention, any one of the methods for producing a high-frequency dielectric material described above includes a step of extruding a sheet-like material containing the thermoplastic resin and the inorganic powder, and , a method for producing a high-frequency dielectric, comprising the step of uniaxially or biaxially stretching the sheet-like material.

In one embodiment of the resin composition of the present invention, the high frequency dielectric is a uniaxially or biaxially stretched sheet with a thickness of 20 μm or more and 1000 μm or less and a stretching ratio of 1.1 times or more and 10.0 times or less. A dielectric is shown.

According to the present invention, it is possible to provide a high-frequency dielectric that has both good high-frequency characteristics and mechanical characteristics and is advantageous in terms of cost.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on embodiments.

≪High frequency dielectric≫
The high-frequency dielectric of the present invention is a thermoplastic resin composition containing a thermoplastic resin and an inorganic powder at a mass ratio of 50:50 to 10:90, and the ratio at a frequency of 1 GHz or higher and a temperature of 25 ° C. The dielectric constant ε is 5 or less, and the dielectric loss tangent tan δ is 1×10 ⁻³ or less. In the thermoplastic resin composition, the thermoplastic resin is polyolefin resin, and the inorganic powder is heavy calcium carbonate powder. These thermoplastic resins and inorganic powders are described below.

≪Polyolefin resin≫
The polyolefin resin that can be used for the high-frequency dielectric according to the present invention is not particularly limited, and various resins can be used depending on the application, function, etc. of the composition. Polyolefin-based resin is a polyolefin-based resin having olefin component units as a main component, and specifically includes polypropylene-based resin, polyethylene-based resin, polymethyl-1-pentene, cyclic olefin polymer, and ethylene-cyclic olefin copolymer. Polyolefin resins such as coalescence; ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, metal salt of ethylene-methacrylic acid copolymer (ionomer), ethylene-alkyl acrylate functional group-containing polyolefin resins such as ester copolymers, ethylene-alkyl methacrylate copolymers, maleic acid-modified polyethylene, maleic acid-modified polypropylene, and mixtures of two or more thereof. The above-mentioned "mainly composed" means that the olefin component unit is contained in the polyolefin resin in an amount of 50% by mass or more, and the content is preferably 75% by mass or more, more preferably 85% by mass. % or more, more preferably 90 mass % or more. In particular, resins in which substantially all of the monomer components are olefins, especially polyolefin homopolymers (homopolymers) are preferred. The method for producing the polyolefin resin used in the present invention is not particularly limited, and can be obtained by any method using a radical initiator such as a Ziegler-Natta catalyst, a metallocene catalyst, oxygen, or a peroxide. It may be something else.

Examples of the polypropylene-based resin include resins having a propylene component unit of 50% by mass or more, and examples thereof include propylene homopolymers and copolymers of propylene and other copolymerizable monomers. Propylene homopolymers include isotactic, syndiotactic, atactic, hemiisotactic, and linear or branched polypropylenes exhibiting various stereoregularities. The above copolymer may be a random copolymer or a block copolymer, and may be a terpolymer as well as a binary copolymer. Copolymerization components (other monomers) include, but are not limited to, tetrafluoroethylene, vinyl acetate, and the like. In the present invention, it is preferable to use a homopolymer or a resin copolymerized with a small amount of another monomer, for example, less than 5% by weight. It should be noted that even in propylene homopolymers, as a result of polymerization, there are cases where a structure as if an α-olefin such as hexene is copolymerized is partly included, but in the present invention, such a polymer is also included. , is broadly included as a propylene homopolymer (propylene homopolymer). Moreover, these polypropylene resins can be used individually or in mixture of 2 or more types.

Examples of the polyethylene-based resin include resins having an ethylene component unit of 50% by mass or more. Examples include high-density polyethylene (HDPE), low-density polyethylene (LDPE), medium-density polyethylene, and linear low-density polyethylene (LLDPE). , ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-propylene-butene 1 copolymer, ethylene-butene 1 copolymer, ethylene-hexene 1 copolymer, ethylene-4-methylpentene 1 copolymer Coalescing, ethylene-octene 1 copolymer, etc., and mixtures of two or more thereof.

Among the polyolefin resins described above, polypropylene resins and/or polyethylene resins, particularly polypropylene resins, are preferably used because of their particularly excellent balance between mechanical properties and heat resistance. Among them, propylene homopolymer is preferred. As described above, the propylene homopolymer may be linear or branched polypropylene having various steric structures, and its molecular weight is not particularly limited. Propylene homopolymer, particularly isotactic polypropylene, is a thermoplastic resin having a low dielectric constant and dielectric loss tangent among various polymer materials, and is suitable for the high-frequency dielectric of the present invention. A plurality of propylene homopolymers having different steric structures and molecular weights can be used together.

In the high-frequency dielectric of the present invention, the thermoplastic resin is the polyolefin resin as described above, but may further contain resin components other than these. Thermoplastic resins such as poly (meth) acrylic acid (ester), polyvinyl acetate, polyacrylonitrile, polystyrene, ABS resin, polycarbonate, polyamide, polyvinyl alcohol, petroleum hydrocarbon resin, coumarone-indene resin; Elastomers such as butadiene copolymers, styrene-isoprene copolymers, styrene-butadiene-ethylene copolymers, styrene-isoprene-ethylene copolymers, acrylonitrile-butadiene copolymers, fluorine-based elastomers, etc., may be mentioned. Not limited. By blending these resin components, each component can be more uniformly dispersed in the resin composition constituting the high-frequency dielectric, and physical properties and workability can be improved. However, considering the compatibility of various resin components, etc., the thermoplastic resin in the high-frequency dielectric of the present invention is preferably 90% by mass or more, more preferably 97% by mass or more, and particularly preferably substantially the entire amount of the above. Made of polyolefin resin. If the high-frequency dielectric does not substantially contain resin components other than polyolefin resin, it is particularly easy to select raw materials, compositions, and processing conditions.

≪Heavy calcium carbonate powder≫
In the high-frequency dielectric according to the present invention, heavy calcium carbonate powder is used as the inorganic powder. Here, heavy calcium carbonate is obtained by mechanically pulverizing and processing natural limestone or the like, and is clearly distinguished from synthetic calcium carbonate produced by chemical precipitation reaction or the like. The pulverization method includes a dry method and a wet method, and the dry method is preferred.

The heavy calcium carbonate powder, for example, differs from the synthetic light calcium carbonate in that it is characterized by surface irregularities and a large specific surface area due to the fact that the particles are formed by pulverization. Since the heavy calcium carbonate powder has such an irregular shape and a large specific surface area, when blended in a thermoplastic resin, the heavy calcium carbonate powder has a larger contact interface with the thermoplastic resin. It has an effect on uniform dispersion.

In order to enhance the dispersibility or reactivity of the heavy calcium carbonate powder, the surface may be surface-modified by a conventional method. Examples of surface modification methods include physical methods such as plasma treatment, and chemical surface treatment using a coupling agent or surfactant. Examples of coupling agents include silane coupling agents and titanium coupling agents. Surfactants may be anionic, cationic, nonionic or amphoteric, and examples thereof include higher fatty acids, higher fatty acid esters, higher fatty acid amides and higher fatty acid salts. On the contrary, it may contain heavy calcium carbonate powder that is not surface-treated.

Although not particularly limited, the heavy calcium carbonate powder preferably has a BET specific surface area of 0.1 m ² /g or more and 10.0 m ² /g or less. When the specific surface area is within this range, there is a tendency to suppress deterioration in processability of the obtained molded article.

In addition, the amorphousness of the heavy calcium carbonate powder (particles) can be expressed by a low degree of spheroidization of the particle shape, and is not particularly limited. It is 0.50 or more and 0.95 or less, more preferably 0.55 or more and 0.93 or less, and still more preferably 0.60 or more and 0.90 or less. If the roundness of the heavy calcium carbonate powder is within this range, the strength and moldability of the molded product will be moderate. Here, the circularity can be expressed by (the projected area of the grain)/(the area of the circle having the same circumferential length as the projected circumferential length of the grain). The method for measuring the roundness is not particularly limited, and for example, the projected area and the projected peripheral length of the grain may be measured from a micrograph, or image analysis software that is generally commercially available may be used.

The heavy calcium carbonate powder is not particularly limited, but preferably has an average particle size of 0.7 μm or more and 7.0 μm or less, more preferably 0.8 μm or more and 6.0 μm or less, and further preferably, It is 1.0 μm or more and 4.0 μm or less. The average particle size of the heavy calcium carbonate powder described in this specification is a value calculated from the results of measuring the specific surface area by an air permeation method according to JIS M-8511. As a measuring device, for example, a specific surface area measuring device SS-100 manufactured by Shimadzu Corporation can be preferably used. When the average particle size is larger than 7.0 μm, for example, when a sheet-like molded product is formed, the heavy calcium carbonate powder protrudes from the surface of the molded product, depending on the layer thickness of the molded product. may fall off, or the surface properties, mechanical strength, etc. may be impaired. In particular, the particle size distribution preferably does not contain powder (particles) having a particle size of 45 μm or more. On the other hand, if the particles are too fine, the viscosity will increase significantly when kneaded with the above-mentioned resin, which may make it difficult to produce molded articles. Such a problem can be prevented by setting the average particle size of the inorganic powder to 0.7 μm or more and 7.0 μm or less, particularly 0.8 μm or more and 6.0 μm or less.

In the present invention, the heavy calcium carbonate powder contains at least two groups of particles having different average particle sizes, and the at least two groups of particles having different average particle sizes are air according to JIS M-8511. A first calcium carbonate particle group having an average particle size of 0.7 μm or more and less than 2.2 μm by a permeation method, and a second calcium carbonate particle group having an average particle size of 2.2 μm or more and 7.0 μm or less by an air permeation method according to JIS M-8511. and calcium carbonate particles at a mass ratio of 1:1 to 5:1. As a result, it is possible to improve the surface properties of the high-frequency dielectric material, as well as physical properties such as printability and blocking properties. In addition, uneven distribution of calcium carbonate is suppressed, a high-frequency dielectric with good appearance and mechanical properties such as elongation at break can be obtained, and falling off of calcium carbonate from the high-frequency dielectric can be reduced.

Although not particularly limited, when the average particle size of the first calcium carbonate particle group is a and the average particle size of the second calcium carbonate particle group is b, the a/b ratio is 0.85 or less, It is desirable to be able to classify roughly so that it is more preferably about 0.10 to 0.70, and still more preferably about 0.10 to 0.50. This is because a particularly excellent effect can be expected by jointly using particles having such a clear difference in average particle size to some extent. Further, each of the first calcium carbonate particle group and the second calcium carbonate particle group preferably has a coefficient of variation (Cv) of the distribution of the particle size (μm) of about 0.01 to 0.10, particularly 0 It is desirable to be about 0.03 to 0.08. If the variation in particle size defined by the coefficient of variation (Cv) is this level, it is considered that each powder group can provide more complementary effects. Three or more calcium carbonate groups having different average particle size distributions may be used. Moreover, it is preferable that each of the powders of the first calcium carbonate particle group and the second calcium carbonate particle group is surface-treated ground calcium carbonate.

In the high-frequency dielectric of the present invention, the inorganic substance powder is the heavy calcium carbonate powder as described above, but may further contain inorganic substance powders other than these. Examples include powdery carbonates, sulfates, silicates, phosphates, borates, oxides, or hydrates thereof of calcium, magnesium, aluminum, titanium, iron, zinc, etc. Specifically, for example, light calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, Aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, wollastonite, dolomite, Graphite etc. are mentioned. These may be synthetic or derived from natural minerals, and may be contained singly or in combination of two or more.

Considering the physical properties and moldability of the high-frequency dielectric, the inorganic powder in the high-frequency dielectric of the present invention is preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably excluding unavoidable impurities. Substantially the entire amount consists of the ground calcium carbonate powder described above. If the high-frequency dielectric does not substantially contain inorganic substance powders other than heavy calcium carbonate powder, physical properties such as high-frequency characteristics and mechanical characteristics will be particularly good.

<<Thermoplastic resin composition>>
The high-frequency dielectric of the present invention is composed of a thermoplastic resin composition containing the above thermoplastic resin and inorganic powder. In the thermoplastic resin composition, the thermoplastic resin and the inorganic powder are contained in a mass ratio of 50:50 to 10:90. If the content of the inorganic substance powder is too small, it is difficult to obtain the physical properties such as texture and strength of the thermoplastic resin composition.

In addition, in the thermoplastic resin composition, the ratio of the inorganic substance powder to the total mass of the thermoplastic resin and the inorganic substance powder is preferably 52% by mass or more, more preferably 55% by mass or more. The upper limit of the ratio is preferably 80% by mass or less, more preferably 75% by mass or less, and particularly preferably 70% by mass or less.

If necessary, other additives may be added as auxiliary agents to the thermoplastic resin composition constituting the high-frequency dielectric. Other additives include, for example, colorants, lubricants, coupling agents, fluidity modifiers (fluidity modifiers), cross-linking agents, dispersants, antioxidants, ultraviolet absorbers, flame retardants, stabilizers, and electrifying agents. Inhibitors, foaming agents, plasticizers, etc. may be blended. These additives may be used alone or in combination of two or more. Moreover, these may be blended in the kneading step described later, or may be blended in the raw material components in advance before the kneading step.

In the thermoplastic resin composition, the addition amount of these other additives is not particularly limited as long as it does not inhibit the desired physical properties and processability, but the mass of the entire thermoplastic resin composition is 100%. In this case, each of these other additives should be blended at a ratio of about 0 to 10% by mass, particularly about 0.04 to 5% by mass, and the total amount of the other additives should be 10% by mass or less. is desired. For example, 10 to 45% by mass, particularly 20 to 25% by mass of a thermoplastic resin such as a polyolefin resin in the total 100% by mass of the thermoplastic resin composition constituting the high-frequency dielectric; 90 to 45% by mass, particularly 75 to 55% by weight of inorganic powder such as ground calcium carbonate; and 0 to 10% by weight, particularly 0.04 to 5% by weight of the above additives.

Among these additives, those considered to be important will be described below by way of examples, but the additives are not limited to these.

Examples of plasticizers include triethyl citrate, acetyl-triethyl citrate, dibutyl phthalate, diaryl phthalate, dimethyl phthalate, diethyl phthalate, di-2-methoxyethyl phthalate, dibutyl tartrate, and o-benzoylbenzoic acid. Ester, diacetin, epoxidized soybean oil and the like. These plasticizers are usually blended in about several mass % with respect to the thermoplastic resin, but the amount is not limited to these ranges, and depending on the application of the high frequency dielectric, epoxidized soybean oil etc. Blending is also possible. However, in the high-frequency dielectric of the present invention, the blending amount is preferably about 0.5 to 10 parts by weight, particularly about 1 to 5 parts by weight, per 100 parts by weight of the thermoplastic resin.

As the colorant, any of known organic pigments, inorganic pigments, or dyes can be used. Specifically, organic pigments such as azo-based, anthraquinone-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, diosazine-based, perinone-based, quinophthalone-based, and perylene-based pigments, ultramarine blue, titanium oxide, titanium yellow, and iron oxide. (Rouge), chromium oxide, zinc white, carbon black and other inorganic pigments.

Examples of lubricants include fatty acid-based lubricants such as stearic acid, hydroxystearic acid, complex stearic acid, and oleic acid; fatty alcohol-based lubricants; stearamide, oxystearamide, oleylamide, erucylamide, ricinolamide, behenamide, and methylol. Aliphatic amide-based lubricants such as amides, methylenebisstearamide, methylenebisstearobehenamide, higher fatty acid bisamic acids, complex amides; n-butyl stearate, methyl hydroxystearate, polyhydric alcohol fatty acid esters, Fatty acid ester-based lubricants such as saturated fatty acid esters and ester-based waxes; and fatty acid metal soap-based lubricants such as zinc stearate and magnesium stearate.

Phosphorus-based antioxidants, phenol-based antioxidants, and pentaerythritol-based antioxidants can be used as antioxidants. Phosphorus-based, more specifically phosphorus-based antioxidant stabilizers such as phosphites and phosphates are preferably used. Examples of phosphites include triphenyl phosphite, trisnonylphenyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, and other phosphorous acid triesters, diesters, and monoesters. is mentioned.

Phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris(nonylphenyl) phosphate, 2-ethylphenyl diphenyl phosphate and the like. These phosphorus-based antioxidants may be used alone, or two or more of them may be used in combination.

Phenolic antioxidants include α-tocopherol, butylhydroxytoluene, sinapyl alcohol, vitamin E, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2- t-butyl-6-(3'-t-butyl-5'-methyl-2'-hydroxybenzyl)-4-methylphenyl acrylate, 2,6-di-t-butyl-4-(N,N-dimethyl aminomethyl)phenol, 3,5-di-t-butyl-4-hydroxybenzylphosphonate diethyl ester, and tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane etc., and these can be used alone or in combination of two or more.

Although the flame retardant is not particularly limited, for example, halogen-based flame retardants or non-phosphorus-based halogen-based flame retardants such as phosphorus flame retardants and metal hydrates can be used. Specific examples of halogen flame retardants include halogenated bisphenol compounds such as halogenated bisphenylalkanes, halogenated bisphenyl ethers, halogenated bisphenylthioethers, and halogenated bisphenylsulfones, brominated bisphenol A, bromine Bisphenol-bis(alkyl ether) compounds such as bisphenol S, chlorinated bisphenol A, and chlorinated bisphenol S, and phosphorus-based flame retardants such as aluminum tris(diethylphosphinate) and bisphenol A bis(diphenyl phosphate). , triaryl isopropyl phosphate, cresyl di-2,6-xylenyl phosphate, aromatic condensed phosphate esters, etc., and metal hydrates such as aluminum trihydrate, magnesium hydroxide, combinations thereof, etc. can be exemplified, respectively, and these can be used alone or in combination of two or more. It works as a flame retardant assistant, and can improve the flame retardant effect more effectively. Furthermore, for example, antimony oxides such as antimony trioxide and antimony pentoxide, zinc oxide, iron oxide, aluminum oxide, molybdenum oxide, titanium oxide, calcium oxide, magnesium oxide, etc. can be used in combination as flame retardant aids. .

The foaming agent is mixed or injected into the thermoplastic resin composition in a molten state in a melt-kneader, and undergoes a phase change from solid to gas, liquid to gas, or gas itself. Used to control the porosity (expansion ratio) of high frequency dielectrics. A foaming agent that is liquid at room temperature undergoes a phase change to a gas depending on the resin temperature and dissolves in the molten resin, while a foaming agent that is gas at room temperature does not undergo a phase change and dissolves in the molten resin as it is. The foaming agent dispersed and dissolved in the molten resin expands inside the sheet as the pressure is released when the molten resin is extruded into a sheet from an extrusion die, forming a large number of fine closed cells within the sheet and foaming. A sheet is obtained. The foaming agent secondarily acts as a plasticizer that lowers the melt viscosity of the raw material resin composition, and lowers the temperature for making the raw resin composition plasticized.

Examples of blowing agents include aliphatic hydrocarbons such as propane, butane, pentane, hexane and heptane; alicyclic hydrocarbons such as cyclobutane, cyclopentane and cyclohexane; chlorodifluoromethane, difluoromethane, trifluoromethane, trichlorofluoromethane; Methane, dichloromethane, dichlorofluoromethane, dichlorodifluoromethane, chloromethane, chloroethane, dichlorotrifluoroethane, dichloropentafluoroethane, tetrafluoroethane, difluoroethane, pentafluoroethane, trifluoroethane, dichlorotetrafluoroethane, trichlorotrifluoroethane , tetrachlorodifluoroethane and perfluorocyclobutane; inorganic gases such as carbon dioxide, nitrogen and air; and water.

As the foaming agent, for example, a carrier resin containing an active ingredient of the foaming agent can be preferably used. Examples of carrier resins include crystalline olefin resins. Among these, crystalline polypropylene resins are preferred. Moreover, hydrogen carbonate etc. are mentioned as an active ingredient. Among these, hydrogen carbonate is preferred. A blowing agent concentrate containing a crystalline polypropylene resin as a carrier resin and a hydrogen carbonate as a thermally decomposable blowing agent is preferred.

The content of the foaming agent contained in the foaming agent in the molding process can be appropriately set according to the amounts of the thermoplastic resin and the inorganic substance powder, etc., and is 0.04 to 0.04 with respect to the total mass of the thermoplastic resin composition. A range of 5.00% by mass is preferred.

Various commonly used fluidity modifiers can also be used. Examples include, but are not limited to, peroxides such as dialkyl peroxides such as 1,4-bis[(t-butylperoxy)isopropyl]benzene and the like. Depending on the type of thermoplastic used, these peroxides may also act as crosslinkers. In particular, when the polyolefin resin has diene-derived structural units, part of the copolymer is crosslinked by the action of the peroxide, which helps control the physical properties and workability of the thermoplastic resin composition. obtain. The amount of the peroxide to be added is not particularly limited, but should be in the range of 0.04 to 2.00% by mass, particularly 0.05 to 0.50% by mass, based on the total mass of the thermoplastic resin composition. is preferred.

<Method for preparing thermoplastic resin composition>
As a method for preparing the thermoplastic resin composition, a conventional method can be used, and the method can be appropriately set according to the molding method (extrusion molding, injection molding, vacuum molding, etc.). For example, it can be prepared by melt-kneading a thermoplastic resin and an inorganic powder. Melt-kneading is preferably carried out by applying a high shear stress while dispersing each component uniformly. As a mixing device, various devices such as a general extruder, a kneader, and a Banbury mixer can be used. The prepared thermoplastic resin composition can be made into pellets of desired shape and size, for example, and used to produce the high-frequency dielectric of the present invention. Depending on the desired shape of the high-frequency dielectric, it is also possible to knead each raw material to prepare a thermoplastic resin composition and at the same time to mold the high-frequency dielectric. For example, a sheet-shaped high-frequency dielectric can be produced by kneading various raw materials with a twin-screw extruder and extruding a sheet-shaped material.

<<Manufacturing method of high frequency dielectric>>
The method for producing the high-frequency dielectric of the present invention is not particularly limited as long as it can be molded into a desired shape, and any of conventionally known methods such as extrusion molding, injection molding, vacuum molding, blow molding, and calender molding can be used. may be used. Furthermore, even in the embodiment in which the high-frequency dielectric according to the present invention is a foam, if it can be molded into a desired shape, it can be formed by conventionally known liquid phase foaming methods such as injection foaming, extrusion foaming, foam blowing, etc. , bead foaming, batch foaming, press foaming, normal pressure secondary foaming, and other solid phase foaming methods can be used. In one aspect of the thermoplastic resin composition containing crystalline polypropylene as a carrier resin and a hydrogen carbonate as a thermally decomposable foaming agent, an injection foaming method and an extrusion foaming method can be desirably used.

However, the method for producing a high-frequency dielectric of the present invention includes the steps of extruding a sheet-like material containing the thermoplastic resin and the inorganic powder as described above, and the steps of uniaxially or biaxially stretching the sheet-like material. is preferably included. By such a manufacturing method, it is possible to efficiently manufacture a high-frequency dielectric material, especially a sheet-like high-frequency dielectric material having a desired relative permittivity and dielectric loss tangent at a low cost.

<Extrusion molding process>
The extrusion process is not particularly limited, and various known extrusion processes such as those described above can be used. Considering the smoothness of the surface of the sheet, it is preferable to use a twin-screw extruder, particularly a T-die type twin-screw extruder. Using such a molding machine, for example, the melting point of the thermoplastic resin + 55 ° C. or less, preferably the melting point of the thermoplastic resin or more and the melting point + 55 ° C. or less, more preferably the melting point of the thermoplastic resin + 10 ° C. or more and the melting point of the thermoplastic resin By extruding at a temperature of +45° C. or lower, a high frequency dielectric with excellent appearance and physical properties can be produced.

<Stretching process>
The sheet material extruded as described above is preferably then subjected to a stretching treatment. The stretching treatment is not particularly limited, and the film can be stretched uniaxially, biaxially, or multiaxially (such as by tubular stretching) during or after molding. More preferably, it is uniaxially or biaxially stretched (for example, longitudinally and/or laterally stretched). Moreover, the draw ratio is preferably 1.1 times or more and 10.0 times or less, particularly 1.5 times or more and 5.0 times or less. In the case of biaxial stretching, sequential biaxial stretching or simultaneous biaxial stretching may be used. Such a stretching treatment can improve the mechanical properties of the high-frequency dielectric and facilitate adjustment of the dielectric constant and dielectric loss tangent to appropriate values. Further, a thermoplastic resin composition containing an inorganic powder can be stretched to form minute voids, and as a result, it is possible to reduce the weight of the composition. The porosity of the high-frequency dielectric can also be adjusted by blending the above foaming agent.

<<High frequency dielectric of the present invention>>
As described above, the high-frequency dielectric of the present invention has a dielectric constant ε of 5 or less, preferably 3 or less, and a dielectric loss tangent tan δ of 1×10 ⁻³ or less, preferably 7 at a temperature of 25° C. and a frequency of 1 GHz or higher. ×10 ⁻⁴ or less, more preferably 5×10 ⁻⁴ or less, still more preferably 4×10 ⁻⁴ or less, and particularly preferably 3×10 ⁻⁴ or less, exhibiting excellent high frequency characteristics. It can also be designed as a high-frequency dielectric suitable for various uses and sizes, such as resonators, filters, antennas, circuit boards, and laminated circuit element boards. Moreover, since polyolefin-based resin and heavy calcium carbonate powder are used as main raw materials, it has good mechanical properties and is advantageous in terms of cost. Therefore, it can be suitably used for various dielectric devices.

There are no particular restrictions on the shape and configuration of the high-frequency dielectric of the present invention, and the shape and configuration can be made as desired according to the purpose. In particular, the high frequency dielectric of the present invention has a thickness of 20 μm or more and 1000 μm or less, particularly 50 μm or more and 500 μm or less, and a draw ratio of 1.1 times or more and 10.0 times or less, particularly 1.5 times or more and 5.0 times or less. Uniaxially or biaxially oriented sheets are preferred. A desired shape can be obtained by cutting or shaving the high-frequency dielectric from such a sheet.

The high-frequency dielectric of the present invention also preferably has a porosity of 5% or more and 35% or less, particularly 10% or more, further preferably 15% or more and 30% or less. If the high-frequency dielectric contains fine voids at such a ratio, the dielectric constant and the dielectric loss tangent may decrease. Here, the porosity can be calculated from the density (specific gravity) of the high frequency dielectric. For example, in the case of a sheet made of polypropylene resin and calcium carbonate, the true specific gravity ρ _o of the mixture is calculated from the blending amount using the respective true specific gravities of 0.90 and 2.71. Based on the ratio between that value and the specific gravity ρ of the actual sheet, the porosity can be calculated according to the following formula.
Porosity (volume%) = (1-ρ/ρ _o ) × 100

The porosity and size of the voids in the high-frequency dielectric can be adjusted, for example, by stretching. When the inorganic powder-containing thermoplastic resin composition is stretched, the inorganic particles are used as nuclei for the stretching, so that large voids are formed. It is also possible to adjust the porosity by adding the foaming agent described above. The porosity can also be adjusted by extrusion molding without adding a foaming agent or performing the stretching step. Air entrained in the extruder is usually vented out of the molding machine, but part of it may be caught in the thermoplastic resin composition and form fine voids. Therefore, it is possible to adjust the porosity of the high-frequency dielectric within the above range by examining the extrusion molding conditions.

The present invention will be described in more detail below based on examples. It should be noted that these Examples are intended to provide specific aspects and embodiments in order to facilitate an understanding of the concept and scope of the present invention disclosed herein and recited in the appended claims. For illustrative purposes only, the present invention is in no way limited to these examples.

(Evaluation method)
Each physical property value in the following examples and comparative examples was evaluated by the following methods.

(Average particle size of inorganic substance powder)
Using a specific surface area measuring device SS-100 manufactured by Shimadzu Corporation, it was calculated from the results of measuring the specific surface area by the air permeation method in accordance with JIS M-8511.

(Specific surface area)
Using BELSORP-mini manufactured by Microtrac BELL, it was determined by the nitrogen gas adsorption method.

(Particle roundness)
100 particles are sampled so as to represent the particle size distribution of the powder, and the projection of each particle obtained using an optical microscope is image analyzed using commercially available image analysis software. asked for As the measurement principle, the projected area and the projected perimeter of the particle are measured and defined as (A) and (PM), respectively. Let (B) be the area of a circle with the same perimeter as the projected perimeter of
Roundness=A/B=A×4π/(PM) ²
is a request.

(tensile properties)
Tensile strength and elongation at break were measured using Autograph AG-100kNXplus (Shimadzu Corporation) under conditions of 23° C. and 50% RH in accordance with JIS K 7161-2:2014. A dumbbell-shaped test piece was cut out from a molded product described later. The drawing speed was 50 mm/min.

(Electrical characteristics)
Permittivity and dielectric loss tangent were measured at 25° C. using a cavity resonator at a frequency of 1 GHz in accordance with JIS 2565.
The volume resistivity was measured in accordance with JIS K 6921-2:2018 using a resistivity meter MCP-HT800 manufactured by Nitto Seiko Analyticc Co., Ltd.

(raw materials)
Raw materials used in the following examples and comparative examples were as follows.
- Thermoplastic resin PP: polypropylene homopolymer (manufactured by Prime Polymer Co., Ltd.: Prime Polypro (registered trademark) E111G, melting point 160 ° C.)

・ Inorganic substance powder CC1: Heavy calcium carbonate particles (no surface treatment) Average particle size 1.00 μm, specific surface area 22,000 cm ² /g (Softon 2200, manufactured by Bihoku Funka Kogyo Co., Ltd.)
CC2: Heavy calcium carbonate particles (without surface treatment) Average particle diameter 3.60 μm, specific surface area 6,000 cm / g, circularity: 0.90 (BF100, manufactured by Bihoku Funka Kogyo Co., Ltd.)
CC3: Heavy calcium carbonate particles (fatty acid surface treatment) Average particle size 2.2 μm (Ryton S-4, manufactured by Bihoku Funka Kogyo Co., Ltd.)
MgO: Magnesium oxide fine particles Average particle size 0.2 μm (2000A manufactured by Ube Material)

・ Additive D (antistatic agent): PC-4 (lithium salt) manufactured by Marubishi Yuka Kogyo Co., Ltd.
E (lubricant): magnesium stearate F1 (antioxidant): Adekastab (registered trademark) AO-60 (phenolic antioxidant) manufactured by ADEKA Co., Ltd.
F2 (antioxidant): Adekastab (registered trademark) 2112 (phosphite antioxidant) manufactured by ADEKA Co., Ltd.

[Example 1]
Among the above raw materials, 40 parts by mass of PP, 40 parts by mass of CC1, 20 parts by mass of CC2, and 1 part by mass each of additives D, E, F1, and F2 were mixed with a co-rotating machine manufactured by Parker Corporation. The mixture was put into a twin-screw kneading extruder HK-25D (φ25 mm, L/D=41), extruded into strands at a cylinder temperature of 190 to 200° C., cooled, and cut into pellets.

The pellets prepared as described above are extruded at 220°C by a Laboplastmill single-screw T-die extruder (φ20 mm, L/D = 25) manufactured by Toyo Seiki Seisakusho Co., Ltd., so that the pellets are 4 times larger in the take-up direction. Then, it was stretched at 190° C. to form a sheet having a thickness of about 150 μm. The physical properties of the obtained sheet were evaluated by the above test methods. The evaluation results are shown in Table 1 below together with the composition of the raw materials and the sheet formability.

[Example 2]
Using 30 parts by mass of PP, 70 parts by mass of CC3, and 1 part by mass each of additives D, E, F1, and F2 as raw materials, a sheet having a thickness of about 80 μm was formed, and the sheet was biaxially stretched after forming. Except for this, the same operation as in Example 1 was performed. The biaxial stretching was carried out simultaneously so as to double the length in the drawing direction and double the length in the direction perpendicular to the drawing direction. Evaluation results and the like are shown in Table 1 below.

[Example 3]
The same operation as in Example 1 was performed except that 3 parts by mass of D (antistatic agent) was used as an additive. Evaluation results and the like are shown in Table 1 below.

[Comparative Examples 1 and 2]
The same operation as in Example 1 was performed using the formulation shown in Table 1 without using heavy calcium carbonate powder as the raw material. Evaluation results and the like are shown in Table 1 below.

[Comparative Example 3]
The same operation as in Example 2 was performed except that the amount of PP was 55 parts by mass and the amount of CC3 was 45 parts by mass. Evaluation results and the like are shown in Table 1.

According to the present invention, the sheet of Example 1 containing the polyolefin resin and the heavy calcium carbonate powder at a mass ratio of 50:50 to 10:90 has a specific dielectric The melting point tangent could be lowered without compromising the modulus. The sheet formability was also good, and the tensile strength was also enhanced. On the other hand, in Comparative Example 2 in which magnesium oxide was used as the inorganic substance powder, the dispersion of the powder in the resin was poor, and magnesium oxide exceeding 40 parts by mass could not be filled. In the sheet of Comparative Example 2, the dielectric loss tangent was lower than that of the propylene homopolymer, but the dielectric constant was greatly increased. Moreover, the tensile properties were also low, and it was difficult to put it to practical use. In contrast, the sheets of Examples 1 to 3 according to the present invention exhibited good tensile properties without impairing the dielectric constant. Further, from Example 2 and Comparative Example 3, it was shown that it is necessary to contain the heavy calcium carbonate powder in an amount equal to or greater than that of the thermoplastic resin in order to develop good high-frequency characteristics.

[Example 4]
The same operation as in Example 1 was performed, except that 40 parts by weight of PP, 60 parts by weight of CC3, and 1 part by weight each of additives E, F1, and F2 were used as raw materials. Evaluation results and the like are shown in Table 2 below.

[Example 5]
The same operation as in Example 4 was performed, except that the uniaxial stretching was not performed. Evaluation results and the like are shown in Table 2 below.

[Example 6]
The same procedure as in Example 4 was followed except that the sheet was not stretched after extrusion, but was instead vacuum pressed to form a sheet about 220 μm thick. Evaluation results and the like are shown in Table 2.

Examples 4 and 5 showed that the stretching operation improved the high frequency characteristics. Moreover, Example 6 showed that if the porosity is less than 5%, the high frequency characteristics may not be sufficiently improved.

As shown by the above examples, the present invention provides a high-frequency dielectric having both good high-frequency properties and mechanical properties. Since the high-frequency dielectric of the present invention is mainly composed of polyolefin resin and heavy calcium carbonate powder, it is advantageous in terms of cost.

Claims (10)

A high-frequency dielectric containing a thermoplastic resin and an inorganic powder at a mass ratio of 50:50 to 10:90,
The thermoplastic resin is a polyolefin resin,
The inorganic substance powder is heavy calcium carbonate powder, and has a dielectric constant ε of 5 or less and a dielectric loss tangent tan δ of 1×10 ⁻³ or less at a frequency of 1 GHz or higher and at a temperature of 25° C. High frequency dielectric. 2. The high-frequency dielectric according to claim 1, wherein said thermoplastic resin is a polypropylene-based resin and/or a polyethylene-based resin. 3. The high-frequency dielectric according to claim 1, wherein the ground calcium carbonate powder is surface-treated ground calcium carbonate powder. 4. The high-frequency dielectric according to claim 1, wherein said heavy calcium carbonate powder has an average particle size of 0.7 μm or more and 7.0 μm or less measured by an air permeation method according to JIS M-8511. The heavy calcium carbonate powder has a BET specific surface area of 0.1 m ² /g or more and 10.0 m ² /g or less, and a circularity of 0.50 or more and 0.95 or less. A high-frequency dielectric according to . The heavy calcium carbonate powder contains at least two groups of particles having different average particle sizes, and the at least two groups of particles having different average particle sizes are averaged by an air permeation method according to JIS M-8511. A first calcium carbonate particle group having a particle size of 0.7 μm or more and less than 2.2 μm, and a second calcium carbonate particle group having an average particle size of 2.2 μm or more and 7.0 μm or less measured by an air permeation method according to JIS M-8511. and in a mass ratio of 1: 1 to 5: 1,
A high-frequency dielectric according to any one of claims 1 to 5. 7. The a/b ratio is 0.85 or less, where a is the average particle size of the first calcium carbonate particle group and b is the average particle size of the second calcium carbonate particle group. high frequency dielectric. The high-frequency dielectric according to any one of claims 1 to 7, which has a porosity of 5% or more and 35% or less. 9. The method for producing a high-frequency dielectric according to claim 1, wherein the step of extruding a sheet-like material containing said thermoplastic resin and said inorganic substance powder; A method for producing a high-frequency dielectric, comprising a step of uniaxially or biaxially stretching. The high-frequency dielectric according to any one of claims 1 to 8, wherein the high-frequency dielectric is a uniaxially or biaxially stretched sheet with a thickness of 20 µm or more and 1000 µm or less and a draw ratio of 1.1 times or more and 10.0 times or less. .