WO2021070805A1

WO2021070805A1 - Plate-shaped composite material

Info

Publication number: WO2021070805A1
Application number: PCT/JP2020/037835
Authority: WO
Inventors: 晋平八鍬; 駿二今村
Original assignee: 日東電工株式会社
Priority date: 2019-10-10
Filing date: 2020-10-06
Publication date: 2021-04-15
Also published as: KR20220080069A; TW202115174A; JPWO2021070805A1

Abstract

Provided is an excellent plate-shaped composite material that is well balanced with respect to various characteristics such as relative permittivity and dielectric tangent. This excellent plate-shaped composite material is well balanced in a variety of characteristics such as relative permittivity and dielectric tangent, includes a fluorinated resin and a filler, and is characterized in that: the filler comprises non-porous inorganic fine particles having an average primary particle diameter of 2-50 μm and a porous inorganic fine particle aggregate formed as a result of aggregation of inorganic fine particles having an average primary particle diameter of 5-200 nm; the total content of the porous inorganic fine particle aggregate and the non-porous inorganic fine particles is 20-90 mass% of the composite material; and the mass ratio of the content of the non-porous inorganic fine particles to the total content of the porous inorganic fine particle aggregate and the non-porous inorganic fine particles (content of non-porous inorganic fine particles/(content of porous inorganic fine particle aggregate + content of non-porous inorganic fine particles)) is 0.15-0.90.

Description

Plate-shaped composite material

The present invention relates to a plate-shaped composite material suitable for a substrate or the like of a microstrip patch antenna used as a millimeter-wave radar or the like.

In recent years, in the automobile industry, research and development on ADAS (advanced driver assistance systems) and autonomous driving have been actively carried out, and the importance of millimeter-wave radar as a sensing technology to support this is increasing. As a millimeter-wave radar for automobiles, the use of a "microstrip patch antenna", which is a flat antenna with antenna elements (patches) printed and wired on a resin substrate, from the viewpoint of small size, high performance, and low price. Is influential, and studies on antenna pattern design and substrate materials are underway for higher performance.

Polytetrafluoroethylene (PTFE), which has a small dielectric loss tangent, is one of the most promising substrate materials used for these antennas, and in order to further improve mechanical properties, thermal properties, and electrical properties, It has been proposed to blend granular fillers such as boron nitride, silicon dioxide (silica) and titanium oxide (Titania), and fillers such as glass fiber and carbon fiber (see Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 03-212987 Japanese Unexamined Patent Publication No. 06-119810

The present invention provides an excellent plate-shaped composite material that is harmonious with respect to various properties such as relative permittivity and dielectric loss tangent.

As a result of diligent studies to solve the above problems, the present inventors have made a ratio by including a specific porous inorganic fine particle aggregate and a specific non-porous inorganic fine particle in a specific range in a fluororesin. We have found that it is an excellent composite material that is harmonious in terms of various properties such as permittivity and dielectric loss tangent.
That is, the present invention is as follows.
<1> A plate-shaped composite material containing a fluororesin and a filler, wherein the filler is a porous inorganic fine particle agglomerate formed by aggregating inorganic fine particles having an average primary particle diameter of 5 to 200 nm. It contains non-porous inorganic fine particles having an average primary particle diameter of 0.2 to 50 μm, and the total content of the porous inorganic fine particle aggregates and the non-porous inorganic fine particles is 20 to 90% by mass of the composite material. Mass ratio of the content of the non-porous inorganic fine particles to the total content of the porous inorganic fine particle aggregates and the non-porous inorganic fine particles (content of the non-porous inorganic fine particles / (the porous inorganic fine particle aggregates) + Content of the non-porous inorganic fine particles)) is 0.15 to 0.90, which is a plate-shaped composite material.
<2> The plate-shaped composite material according to <1>, which has a porosity of 15% by volume or more.

According to the present invention, it is possible to provide an excellent plate-shaped composite material that is harmonious with respect to various properties such as relative permittivity and dielectric loss tangent.

It is an SEM photographed image of a porous inorganic fine particle agglomerate formed by aggregating inorganic fine particles having an average primary particle diameter of 5 to 200 nm (drawing substitute photograph). It is a graph which showed the relationship between the filler content and the dielectric loss tangent of a plate-shaped composite material which concerns on Example-Comparative Examples. It is a graph which showed the relationship between the filler content and the coefficient of thermal expansion of the plate-shaped composite material which concerns on Example-Comparative Example.

In explaining the present invention, specific examples will be given, but the contents are not limited to the following as long as the gist of the present invention is not deviated, and the present invention can be modified as appropriate.

≪Plate-shaped composite material≫
The plate-shaped composite material (hereinafter, may be abbreviated as “composite material”) which is one aspect of the present invention is a plate-shaped composite material containing a fluororesin and a filler, and the filler is “average”. Porous inorganic fine particle agglomerates formed by aggregating inorganic fine particles having a primary particle diameter of 5 to 200 nm (hereinafter, may be abbreviated as “inorganic fine particle agglomerates”) ”and“ average primary particle diameter 0.2 to 50 μm of non-porous inorganic fine particles (hereinafter, may be abbreviated as “non-porous inorganic fine particles”) ”, and the total content of the inorganic fine particle aggregates and the non-porous inorganic fine particles is 20 to 90 of the composite material. It is mass%, and is the mass ratio of the content of the non-porous inorganic fine particles to the total content of the inorganic fine particle aggregates and the non-porous inorganic fine particles (content of the non-porous inorganic fine particles / (content of the inorganic fine particle aggregate +). The content of non-porous inorganic fine particles)) is 0.15 to 0.90.
As a result of diligent studies on a plate-shaped composite material that can be used as a substrate for a microstrip patch antenna or the like, the present inventors have made it possible to include inorganic fine particle aggregates and non-porous inorganic fine particles in the above-mentioned range. They have found that the advantages of each filler are appropriately expressed, and that the composite material is excellent in harmony with respect to various properties such as relative permittivity and dielectric loss tangent.
Hereinafter, the "fluorine-based resin" and the "filler" such as "inorganic fine particle aggregate" and "non-porous inorganic fine particle" will be described in detail.

<Fluorine resin>
The type of the fluororesin is not particularly limited, and the fluororesin used for the substrate or the like can be appropriately adopted.
As the fluororesin, usually polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTEF), tetrafluoroethylene. -Ethylene copolymer (ETFE), chlorotrifluoethylene-ethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF) can be mentioned, but PTFE is particularly preferable. These can be used alone or in combination of two or more.

Fluorine-based resin is preferably "fibrillated (fibrous structure)". It is more preferable that the fibers in fibrillation are oriented not only in one direction but also in multiple directions, and the fibril and the inorganic fine particle agglomerates described later are connected to form a "three-dimensional fine network structure". Is particularly preferred. When the fluororesin is fibrillated, particularly when it forms a three-dimensional fine network structure, excellent mechanical strength and dimensional stability can be ensured as a composite material. The fibrillation of the fluororesin can be confirmed by observing the surface with an SEM or the like. Further, the fibrillation of the fluororesin can be promoted by, for example, applying a shearing force, and more specifically, it can be performed by multi-step rolling described later, and the three-dimensional fine network structure will be described later. It can be done by multi-step rolling in different directions.

<Filler>
The composite material will contain inorganic fine particle agglomerates and non-porous inorganic fine particles as fillers, and the inorganic fine particle agglomerates are specifically as shown in the SEM photographed image of FIG. It means that a plurality of inorganic fine particles are fused to form an agglomerate and have voids between the inorganic fine particles to be porous. The inorganic fine particles in the aggregate may be fused at the time of formulation, and the fusion may be released by subsequent mixing with a fluororesin or the like.
On the other hand, the "non-porous" of the non-porous inorganic fine particles is an expression for "porous" that is characteristic of the inorganic fine particles, and the non-porous inorganic fine particles may be any inorganic fine particles that are not "porous". To do. That is, the non-porous inorganic fine particles do not have to have no pores, and may have pores as long as they are not recognized as “porous”.
Hereinafter, the "inorganic fine particle aggregate" and the "non-porous inorganic fine particle" will be described in detail.

(Inorganic fine particle agglomerates)
The material of the inorganic fine particles in the inorganic fine particle aggregate is usually an oxide of a typical element such as silicon oxide (silicon monoxide, silicon dioxide (silica), etc.), aluminum oxide (alumina) (including a composite oxide); oxidation. Transition metal oxides (including composite oxides) such as titanium (titanium dioxide (titania), etc.), iron oxide, zirconium oxide (zirconia dioxide (zirconia)); nitrides of typical elements such as boron nitride and silicon nitride, etc. However, oxides of main group elements are preferable, and silicon dioxide (silica) is particularly preferable. When it is an oxide of a main group element, the relative permittivity of the composite material can be suppressed to an extremely low level, and the composite material can be produced at a lower cost. The crystallinity of the inorganic fine particles is not particularly limited, but in the case of silicon dioxide, it is usually amorphous.

The average primary particle size of the inorganic fine particles in the inorganic fine particle aggregate is 5 to 200 nm, preferably 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more, preferably 150 nm or less, more preferably 120 nm or less. It is more preferably 100 nm or less, particularly preferably 80 nm or less, and most preferably 70 nm or less. Within the above range, the inorganic fine particle agglomerates are not easily broken even if the treatments such as mixing, molding, and rolling are performed, good voids can be secured between the inorganic fine particles, and the plate-like composite material is smooth. It becomes easier to secure the surface. The average primary particle size of the inorganic fine particles in the inorganic fine particle aggregate is a value obtained by measuring the particle size by observation with SEM and averaging the measured values. Specifically, it is a procedure in which inorganic fine particle aggregates (100 particles) are randomly selected, the particle diameters (major diameters of the particles) are measured, and the obtained particle diameters are averaged to obtain a numerical value.

The average particle size of the primary agglomerates of the inorganic fine particles in the inorganic fine particle agglomerates is usually 100 nm or more, preferably 120 nm or more, more preferably 150 nm or more, and usually 400 nm or less, preferably 380 nm or less, more preferably 350 nm or less. .. The average particle size of the secondary agglomerates of the inorganic fine particles (aggregates of the primary agglomerates) in the inorganic fine particle agglomerates is usually 0.1 μm or more, preferably 1 μm or more, more preferably 2 μm or more, and usually 100 μm or less, preferably 100 μm or less. Is 90 μm or less, more preferably 80 μm or less. The inorganic fine particle agglomerates in the composite material are preferably in the state of secondary agglomerates. In the state of secondary agglomerates, the above-mentioned three-dimensional fine network structure is easily formed. Further, the average particle size of the primary agglomerates and the average particle size of the secondary agglomerates can be calculated by the same method as the average primary particle size of the inorganic fine particles in the above-mentioned inorganic fine particle agglomerates.

BET specific surface area of the inorganic particulate aggregate is usually 10 m ² / g or more, preferably 20 m ² / g or more, more preferably 30 m ² / g or more, still more preferably 40 m ² / g or more and usually 250 meters ² / g Below, it is preferably 240 m ² / g or less, more preferably 210 m ² / g or less, still more preferably 150 m ² / g or less, and particularly preferably 80 m ² / g or less. Within the above range, a high porosity can be ensured as a composite material, and an increase in dielectric loss tangent can be suppressed. In particular, if the BET specific surface area is too high, the dielectric loss tangent of the composite material tends to be high. The BET specific surface area of the inorganic fine particle agglomerates is a numerical value calculated by substituting the gas adsorption amount measured by the gas adsorption method (particularly the nitrogen adsorption isotherm) into the BET formula, and is used before being used in the production of composite materials. It shall be expressed numerically.

The apparent specific gravity of the inorganic fine particle aggregate is usually 10 g / L or more, preferably 20 g / L or more, more preferably 30 g / L or more, still more preferably 40 g / L or more, and usually 100 g / L or less, preferably 90 g / L or more. It is L or less, more preferably 80 g / L or less, still more preferably 70 g / L or less, and particularly preferably 60 g / L or less. Within the above range, a high porosity can be ensured as a composite material, and inorganic fine particle aggregates are less likely to be destroyed. The apparent specific gravity of the inorganic fine particle agglomerates is determined by filling the inorganic fine particle agglomerates in a container such as a 250 mL graduated cylinder that can measure the volume, and measuring the filling mass (Xg) and the filling volume (YmL) of the inorganic fine particle agglomerates. , The filling mass is divided by the filling volume ([apparent specific gravity (g / L)] = X / Y × 1000).

As inorganic fine particle aggregates, commercially available products such as Mizukasil series (manufactured by Mizusawa Industrial Chemical Ltd.), Cyricia series (manufactured by Fuji Silysia Chemical Ltd.), AEROSIL series (manufactured by Nippon Aerosil), Nipseal series (manufactured by Toso Silica) Can be preferably used, and among them, fumed silica of the AEROSIL series (manufactured by Aerosil Japan Co., Ltd.) is particularly preferable.

(Non-porous inorganic fine particles)
The material of the non-porous inorganic fine particles is usually an oxide of a typical element such as silicon oxide (silicon monoxide, silicon dioxide (silica), etc.), aluminum oxide (alumina) (including a composite oxide); titanium oxide (including composite oxide). Titanium dioxide (titania), etc.), iron oxide, transition metal oxides such as zirconium oxide (zirconia dioxide (zirconia)) (including composite oxides); nitrides of typical elements such as boron nitride and silicon nitride. Of these, silicon oxide is preferable. Examples of the composite oxide include codylite, talc, wallastnite, mullite, steatite, and forsterite. The material of the non-porous inorganic fine particles is not limited to one type, and two or more types may be combined.

The average primary particle size of the non-porous inorganic fine particles is 0.2 to 50 μm, preferably 0.3 μm or more, more preferably 0.4 μm or more, still more preferably 0.5 μm or more, and preferably 40 μm or less. , More preferably 30 μm or less, still more preferably 20 μm or less, particularly preferably 10 μm or less, and most preferably 5 μm or less. Within the above range, an appropriate specific surface area can be obtained to ensure a good dielectric loss tangent, and the surface of the composite material can be easily made smooth, which makes the material more suitable for a high-frequency substrate. The average primary particle size of the non-porous inorganic fine particles is a value obtained by measuring the particle size by observation with SEM and averaging the measured values. Specifically, it is a procedure in which inorganic fine particle aggregates (100 particles) are randomly selected, the particle diameters (major diameters of the particles) are measured, and the obtained particle diameters are averaged to obtain a numerical value.

The BET specific surface area of the non-porous inorganic fine particles is usually 0.1 m ² / g or more, preferably 0.5 m ² / g or more, more preferably 1 m ² / g or more, still more preferably 2 m ² / g or more. It is usually 30 m ² / g or less, preferably 25 m ² / g or less, more preferably 20 m ² / g or less, still more preferably 15 m ² / g or less, and particularly preferably 10 m ² / g or less. Within the above range, good dielectric loss tangent can be ensured, and the surface of the composite material can be easily made a smooth surface, which makes the material more suitable for a high-frequency substrate. The BET specific surface area of the non-porous inorganic fine particles is a numerical value calculated by substituting the gas adsorption amount measured by the gas adsorption method (particularly the nitrogen adsorption isotherm) into the BET formula, and is used before the production of the composite material. It shall be represented by the numerical value of.

The relative permittivity of the non-porous inorganic fine particles is usually 10 or less, preferably 8 or less, more preferably 7 or less, still more preferably 6 or less, particularly preferably 5 or less, and usually 3 or more. The relative permittivity of the non-porous inorganic fine particles is a numerical value determined by a method conforming to the Japanese Industrial Standards JIS C2565.

Commercially available non-porous inorganic fine particles include fused silica such as SFP-130MC, SFP-30M, and FB-3SDC manufactured by Denka, talc light powder FINE type manufactured by AGC Ceramics, and Koji such as ELP-150N and ELP-325N. Examples thereof include light, boron nitride such as FS-1, HP-P1 and HP40J series manufactured by Mizushima Ferroalloy Co., Ltd., and talc such as Nano Ace D-600, D-800, D-1000 and FG-15 manufactured by Nippon Tarku Co., Ltd.

(Other fillers)
The composite material may contain an inorganic fine particle agglomerate and a filler that does not correspond to the non-porous inorganic fine particle (hereinafter, may be abbreviated as “other filler”), and the inorganic fine particle agglomerate and the filler may be used as the filler. It is also preferable that it consists of only non-porous inorganic fine particles. Examples of other fillers include granular fillers and fibrous fillers, and examples of the granular fillers include solid carbons such as carbon black and graphite; hollow inorganic particles such as silica balloons and glass balloons, and the like. Examples of the fibrous filler include glass fiber and carbon fiber. The other fillers are not limited to one type, and two or more types may be combined.

The surface of the filler (including inorganic fine particle aggregates and non-porous inorganic fine particles) is modified with a surface modifier having a hydrophobic group (hereinafter, may be abbreviated as "surface modifier"). Is preferable.
Hereinafter, modification by the "surface modifier" will be described in detail.

Examples of the hydrophobic group of the surface modifier include a fluoro group (-F) and a hydrocarbon group (-C _n H _{2n + 1} (n = 1 to 30)), but not only for water but also for oil agents. However, a fluorogroup that exhibits liquid repellency is particularly preferable.
The surface modifier may be one that chemically adsorbs (reacts) to the surface of the filler, one that physically adsorbs to the surface of the filler, or a low molecular weight compound. , It may be a polymer compound. A surface modifier that chemically adsorbs (reacts) to the surface of the filler usually has a reactive functional group that reacts with the surface functional group (hydroxyl group (-OH), etc.) of the filler. Examples of the reactive functional group include an alkoxysilyl group (-SiOR (R has 1 to 6 carbon atoms)), a chlorosilyl group (-SiCl), a bromosilyl group (-SiBr), a hydrosilyl group (-SiH) and the like. As a method for modifying the surface of the filler with a surface modifier, a known method can be appropriately adopted, and examples thereof include contacting the filler with the surface modifier.

The surface modifier can be used alone or in combination of two or more. For example, a surface modifier of a low molecular weight compound having a reactive functional group is reacted with the surface of the filler, and then hydrophobic. The surface modifier of the polymer compound having a group may be physically adsorbed. If the material of the filler is silicon dioxide (silica) or the like, it may be dissolved (decomposed) when exposed to a basic aqueous solution, but such modification enhances the resistance to the basic aqueous solution. Can be done.

The thermal decomposition temperature of the surface modifier is usually 250 ° C. or higher, preferably 300 ° C. or higher, more preferably 350 ° C. or higher, further preferably 360 ° C. or higher, and particularly preferably 370 ° C. or higher. Within the above range, decomposition can be suppressed even if a treatment such as high temperature heating is performed. The thermal decomposition temperature of the surface modifier is set to a temperature at which the weight is reduced by 5% when the temperature is raised at 20 ° C./min by the thermogravimetric analysis method (TG-DTA).

Examples of the surface modifier of the low molecular weight compound having a fluoro group and a reactive functional group include those represented by the following formulas. The compound represented by the following formula is commercially available, and can be appropriately obtained and used as a surface modifier.

Examples of the surface modifier of the polymer compound having a fluoro group include those represented by the following formulas.

A commercially available solution may be used as the surface modifier, and preferred ones include T1770 manufactured by Tokyo Chemical Industry Co., Ltd. and Novec® 2202 manufactured by 3M Co., Ltd. It has been published that Novec® 2202 contains a polymer compound having a fluoro group and contains a "fluoroalkylsilane polymer". When Novec (registered trademark) 2202 is used as a surface modifier, it has a feature that the critical liquid repellent tension of the composite material can be easily suppressed to a low level by a relatively simple operation.

The content of the surface modifier (content of organic matter) in the filler is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, particularly preferably. Is 4% by mass or more, usually 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less, and particularly preferably 20% by mass or less.

(Composite material)
The composite material has a total content of inorganic fine particle agglomerates and non-porous inorganic fine particles of 20 to 90% by mass, and the "total content" is an inorganic fine particle agglomerate when the composite material is 100% by mass. Means the total content of the content of the non-porous inorganic fine particles, and when the inorganic fine particle aggregates and / or the non-porous inorganic fine particles contain two or more types, the total content of all of them is used. It shall mean. The total content of the inorganic fine particle aggregates and the non-porous inorganic fine particles is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, preferably 80% by mass or less, more preferably. Is 75% by mass or less, more preferably 70% by mass or less. Further, when the total of the fluororesin, the inorganic fine particle agglomerates and the non-porous inorganic fine particles is 100 parts by mass, the total content of the inorganic fine particle agglomerates and the non-porous inorganic fine particles is usually 20 to 90 parts by mass. Yes, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, further preferably 50 parts by mass or more, preferably 80 parts by mass or less, more preferably 75 parts by mass or less, still more preferably 70 parts by mass or less. is there. Within the above range, it becomes easy to harmonize various characteristics such as relative permittivity and dielectric loss tangent.

In the composite material, the mass ratio of the content of the non-porous inorganic fine particles to the total content of the inorganic fine particle aggregates and the non-porous inorganic fine particles (content of the non-porous inorganic fine particles / (of the inorganic fine particle aggregates)). Content + content of the non-porous inorganic fine particles)) is 0.15 to 0.90, but is preferably 0.2 or more, more preferably 0.3 or more, still more preferably 0.4 or more, most. It is preferably 0.5 or more, preferably 0.8 or less, more preferably 0.75 or less, still more preferably 0.7 or less, and most preferably 0.65 or less.

The total content of the filler in the composite material is usually 20 to 90% by mass, preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, and preferably 80% by mass or less. It is more preferably 75% by mass or less, still more preferably 70% by mass or less. When the total of the fluororesin and the filler is 100 parts by mass, the total content of the filler is usually 20 to 90 parts by mass, preferably 30 parts by mass or more, and more preferably 40 parts by mass or more. It is more preferably 50 parts by mass or more, preferably 80 parts by mass or less, more preferably 75 parts by mass or less, still more preferably 70 parts by mass or less. Within the above range, it becomes easy to harmonize various characteristics such as relative permittivity and dielectric loss tangent.

The composite material may contain materials other than the above-mentioned fluorine-based resin and filler (including inorganic fine particle aggregates and non-porous inorganic fine particles), but the total content of the fluorine-based resin and filler in the composite material is , Usually 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

The shape of the composite material is plate-like, but the thickness thereof is usually 2.0 to 3000 μm, preferably 10 μm or more, more preferably 50 μm or more, still more preferably 80 μm or more, most preferably 100 μm or more, preferably 100 μm or more. It is 2000 μm or less, more preferably 1000 μm or less, still more preferably 800 μm or less, particularly preferably 600 μm or less, and most preferably 400 μm or less. Within the above range, a good relative permittivity or the like can be secured as a composite material.

The dimensions (maximum diameter, length or width) of the composite material are usually 20 to 1500 mm, but are preferably 30 mm or more, more preferably 40 mm or more, still more preferably 50 mm or more, and most preferably 60 mm or more. It is preferably 1400 mm or less, more preferably 1300 mm or less.

The porosity of the composite material is usually 10 to 90% by volume, but is preferably 15% by volume or more, more preferably 20% by volume or more, still more preferably 30% by volume or more, and particularly preferably 40% by volume or more. It is preferably 80% by volume or less, more preferably 70% by volume or less, and further preferably 60% by volume or less. Within the above range, characteristics such as a good relative permittivity and a coefficient of thermal expansion can be ensured as a composite material. The porosity of the composite material is calculated by measuring the volume of the composite material, the specific gravity and mass of the fluororesin (blending mass), and the specific gravity and mass of the filler (blending mass), and substituting them into the following formula. Let it be a numerical value.
[Porosity (volume%)] = ([Volume of composite material]-[Mass of fluororesin / specific gravity of fluororesin]-[Mass of filler / specific gravity of filler]) / [Volume of composite material] × 100

The relative permittivity (frequency: 10 GHz) of the composite material is usually 3.0 or less, preferably 2.60 or less, more preferably 2.40 or less, still more preferably 2.00 or less, and particularly preferably 1.80 or less. Yes, usually 1.55 or more. The relative permittivity of the composite material is a value of the real part (εr') calculated by measuring the complex permittivity by the cavity resonator permittivity method (measurement frequency: 10 GHz).

The dielectric loss tangent (frequency: 10 GHz) of the composite material is usually 0.01 or less, preferably 0.008 or less, more preferably 0.006 or less, still more preferably 0.004 or less, and particularly preferably 0.002 or less. , Usually 0.0005 or more. The relative permittivity of the composite material is the ratio (εr "/ of the imaginary part (εr") to the real part (εr') calculated by measuring the complex permittivity by the cavity resonator perturbation method (measurement frequency: 10 GHz). εr').

The coefficient of thermal expansion (Z-axis direction) of the composite material is usually 100 ppm / K or less, preferably 90 ppm / K or less, more preferably 80 ppm / K or less, still more preferably 70 ppm / K or less, and particularly preferably 60 ppm / K or less. Most preferably, it is 50 ppm / K or less, and usually 5 ppm / K or more. The coefficient of thermal expansion (Z-axis direction) of the composite material is determined by the laser interferometry (laser thermal expansion meter, measurement temperature range: -50 to 200 ° C., heating rate: 2 ° C./min, atmosphere: He, load load: 17g) is used, and the value is calculated from a formula based on the Japanese Industrial Standards JIS R3251-1990.

The tensile strength of the composite material is usually 1 to 50 MPa, preferably 5 MPa or more, more preferably 7 MPa or more, still more preferably 10 MPa or more, preferably 45 MPa or less, more preferably 40 MPa or less, still more preferably 35 MPa or less. The tensile strength shall be a value measured in accordance with the method specified in Japanese Industrial Standards JIS K7161 (see below for detailed conditions).

The tensile elastic modulus of the composite material is usually 0.05 to 1 GPa, preferably 0.08 GPa or more, more preferably 0.1 GPa or more, still more preferably 0.15 GPa or more, preferably 0.8 GPa or less, more preferably 0.8 GPa or less. It is 0.6 GPa or less, more preferably 0.4 GPa or less. The tensile elastic modulus is a numerical value measured in accordance with the method specified in Japanese Industrial Standards JIS K7161 (see below for detailed conditions).

<Use of composite materials>
The use of the composite material is not particularly limited, but preferably an electronic circuit board, more preferably a circuit board for a mobile phone, a computer, etc., a substrate for a microstrip patch antenna for a millimeter-wave radar, and the like. That is, a substrate containing the above-mentioned composite material (hereinafter, may be abbreviated as "substrate") is also mentioned as one aspect of the present invention.

The substrate contains a composite material, but has a layer (hereinafter, may be abbreviated as "resin layer") containing a thermoplastic resin attached to one side or both sides of the composite material. Is preferable, and a fluororesin is particularly preferable as the thermoplastic resin.
Examples of the fluororesin include polytetrafluoroethylene (PTFE, melting point: 327 ° C.), perfluoroalkoxy alkane (PFA, melting point: 310 ° C.), tetrafluoroethylene / hexafluoropropylene copolymer (FEP, melting point: 260 ° C.). , Polychlorotrifluoroethylene (PCTEF, melting point: 220 ° C.), tetrafluoroethylene / ethylene copolymer (ETFE, melting point: 270 ° C.), chlorotrifluoethylene / ethylene copolymer (ECTFE, melting point: 270 ° C.), poly Vinylidene fluoride (PVDF, melting point: 151 to 178 ° C.) can be mentioned, and PTFE and PFA are particularly preferable. These can be used alone or in combination of two or more.

The thickness of the resin layer is usually 0.050 to 30 μm, but is preferably 0.100 μm or more, more preferably 0.40 μm or more, still more preferably 1.0 μm or more, and most preferably 1.5 μm or more. Is 20 μm or less, more preferably 10 μm or less, still more preferably 8.0 μm or less, particularly preferably 6.0 μm or less, and most preferably 5.0 μm or less. The substrate will be exposed to various chemicals used in the manufacturing process of antennas and the like. For example, when exposed to a highly permeable treatment liquid, the treatment liquid may permeate inside and cause poor appearance or change in characteristics of the substrate. Since the resin layer also has a function of suppressing the permeation of the treatment liquid, if it is within the above range, the peeling of the conductor layer and the like can be effectively suppressed, and the permeability used for manufacturing the electronic circuit board is produced. Even when exposed to a high-grade treatment liquid or the like, poor appearance and changes in characteristics are less likely to occur. The thickness of the resin layer means a value obtained by measuring the distance from the end in the thickness direction of the resin layer to the interface between the composite material and the resin layer at about 5 to 10 points and averaging them.

The resin layer is not only laminated (attached) on only one side of the composite material, but may be laminated on both sides of the composite material.

The peeling strength of the composite material and the resin layer is usually 0.2 to 2.5 N / mm, preferably 0.3 N / mm or more, more preferably 0.4 N / mm or more, still more preferably 0.5 N / mm. The above is preferably 2.4 N / mm or less, more preferably 2.2 N / mm or less, and further preferably 2 N / mm or less. The peeling strength is a numerical value measured in accordance with the method specified in Japanese Industrial Standard JIS C6481: 1996 (see below for detailed conditions).

The substrate is usually provided with a conductor layer, which is usually a metal layer. When the resin layer is provided, the conductor layer is laminated on the resin layer.
Examples of the metal type of the metal layer include gold (Au), silver (Ag), platinum (Pt), copper (Cu), aluminum (Al), and alloys containing these metal types.
The thickness of the metal layer is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and usually 50 μm or less, preferably 45 μm or less, more preferably 40 μm or less.

The maximum height Rz of the contact surface of the conductor layer with respect to the composite material or resin layer is usually 0.020 μm or more, preferably 0.050 μm or more, more preferably 0.10 μm or more, still more preferably 0.20 μm or more, particularly preferably. Is 0.30 μm or more, usually 10 μm or less, preferably 8.0 μm or less, more preferably 6.0 μm or less, still more preferably 4.0 μm or less, and particularly preferably 2.0 μm or less. The "maximum height Rz" is a numerical value determined by a method based on the Japanese Industrial Standards JIS B0601: 2013 (Japanese Industrial Standards created for the International Organization for Standardization standard ISO4287 without changing the technical contents). It shall mean. Further, the "maximum height Rz of the contact surface of the conductor layer with respect to the composite material or the resin layer" may be directly measured or may be considered by using the maximum height Rz of the material used for the conductor layer as it is.

The thickness obtained by subtracting the maximum height Rz of the conductor layer from the thickness of the resin layer ((thickness of the resin layer)-(maximum height Rz of the conductor layer)) is usually 0.005 μm or more, preferably 0.010 μm or more. It is preferably 0.050 μm or more, more preferably 0.10 μm or more, particularly preferably 0.50 μm or more, and usually 29.98 μm or less, preferably 20 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less, particularly preferably. Is 5.0 μm or less. Within the above range, the thickness of the resin layer is sufficiently secured, so that the appearance is poor and the characteristics are changed even when exposed to a highly permeable treatment liquid used for manufacturing electronic circuit boards. Is less likely to occur.

<Manufacturing method of composite material>
The composite material shall be manufactured by a manufacturing method including the following resin preparation step, filler preparation step, mixing step, molding step, and rolling step (hereinafter, may be abbreviated as "composite material manufacturing method"). Is preferable.
-Resin preparation process for preparing a fluororesin (hereinafter, may be abbreviated as "resin preparation process").
-Filler preparation process for preparing a filler (hereinafter, may be abbreviated as "filler preparation process").
-A mixing step of mixing the fluororesin, the filler, and the volatile additive to obtain a precursor composition (hereinafter, may be abbreviated as "mixing step").
A molding step of molding the precursor composition to obtain a rollable object (hereinafter, may be abbreviated as "molding step").
-A rolling step of rolling the object to be rolled to obtain a composite material (hereinafter, may be abbreviated as "rolling step").
Hereinafter, the "resin preparation process", the "filler preparation process", the "mixing process", the "molding process", the "rolling process" and the like will be described in detail.

The resin preparation process is a process of preparing a fluorine-based resin, but the fluorine-based resin may be obtained or manufactured by itself. The average particle size (median diameter d50) of the fluororesin granules (particles after the secondary particles) to be prepared is usually 0.5 μm or more, preferably 1.0 μm or more, more preferably 10 μm or more, still more preferably. It is 30 μm or more, usually 700 μm or less, preferably 300 μm or less, more preferably 150 μm or less, still more preferably 100 μm or less, and particularly preferably 50 μm or less. Within the above range, the fluororesin and the filler can be easily dispersed uniformly. The granulated product of the fluororesin can be determined by a method conforming to Japanese Industrial Standards JIS Z8825: 2001.

The filler preparation step is a step of preparing a filler, and the filler (including inorganic fine particle aggregates and non-porous inorganic fine particles) may be obtained or manufactured by itself. The average particle size (median diameter d50) of the filler to be prepared, particularly the granulated product of the aggregate of inorganic fine particles (particles after the secondary particles), is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm. As described above, it is more preferably 3 μm or more, usually 500 μm or less, preferably 200 μm or less, more preferably 100 μm or less, still more preferably 50 μm or less, and particularly preferably 20 μm or less. The average particle size (median diameter d50) of the granulated product of non-porous inorganic fine particles (particles after the secondary particles) is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, still more preferably 10 μm or more. , Usually 2000 μm or less, preferably 1000 μm or less, more preferably 500 μm or less, still more preferably 100 μm or less, and particularly preferably 50 μm or less. Within the above range, the fluororesin and the filler can be easily dispersed uniformly. The granulated product of the filler can be determined by a method conforming to Japanese Industrial Standards JIS Z8825: 2001.
Further, it is preferable that the surface of the filler is modified with the above-mentioned surface modifier.

Particle size ratio of the average particle size of the granulated product of the fluororesin to be prepared and the granulated product of the inorganic fine particle agglomerates (average particle size of the fluororesin (median diameter d50) / average particle size of the inorganic fine particle agglomerates (median) The diameter d50)) is usually 150 or less, preferably 100 or less, more preferably 60 or less, still more preferably 40 or less, particularly preferably 30 or less, most preferably 10 or less, and usually 1 or more. Particle size ratio of the average particle size of the granulated product of the fluororesin to be prepared and the granulated product of the non-porous inorganic fine particles (average particle size of the fluorine-based resin (median diameter d50) / average particle size of the non-porous inorganic fine particles) (Median diameter d50)) is usually 500 or less, preferably 300 or less, more preferably 200 or less, still more preferably 100 or less, particularly preferably 50 or less, most preferably 30 or less, and usually 0.01 or more. Is. Within the above range, the fluororesin and the filler can be easily dispersed uniformly.

The mixing step is a step of mixing a fluororesin, a filler, and a volatile additive to obtain a precursor composition, but for mixing, a known method such as a dry type or a wet type, a mixer, or the like is appropriately adopted. Can be done.
In the case of the dry type, the rotation speed (peripheral speed) of the stirrer or the like is usually 0.5 m / sec or more, preferably 1 m / sec or more, more preferably 5 m / sec or more, still more preferably 10 m / sec or more, particularly preferably. 15 m / sec or more, usually 200 m / sec or less, preferably 180 m / sec or less, more preferably 140 m / sec or less, still more preferably 100 m / sec or less, particularly preferably 50 m / sec or less, most preferably 20 m / sec. It is as follows. Within the above range, the fluororesin and the filler can be easily dispersed uniformly.

In the case of the dry type, the mixing time is usually 10 seconds or longer, preferably 20 seconds or longer, more preferably 30 seconds or longer, further preferably 40 seconds or longer, particularly preferably 1 minute or longer, most preferably 5 minutes or longer, and usually. It is 60 minutes or less, preferably 50 minutes or less, more preferably 40 minutes or less, still more preferably 30 minutes or less, particularly preferably 20 minutes or less, and most preferably 15 minutes or less. Within the above range, the fluororesin and the filler can be easily dispersed uniformly.

The rotation speed (peripheral speed) of the stirrer or the like in the wet case is usually 1 m / sec or more, preferably 5 m / sec or more, more preferably 10 m / sec or more, still more preferably 15 m / sec or more, and particularly preferably 20 m / sec or more. sec or more, most preferably 25 m / sec or more, usually 160 m / sec or less, preferably 130 m / sec or less, more preferably 100 m / sec or less, still more preferably 80 m / sec or less, particularly preferably 60 m / sec or less, Most preferably, it is 40 m / sec or less. Within the above range, the fluororesin and the filler can be easily dispersed uniformly.

In the wet case, the mixing time is usually 5 seconds or longer, preferably 10 seconds or longer, more preferably 20 seconds or longer, still more preferably 30 seconds or longer, particularly preferably 40 seconds or longer, most preferably 50 seconds or longer, and usually. It is 60 minutes or less, preferably 50 minutes or less, more preferably 40 minutes or less, still more preferably 20 minutes or less, particularly preferably 10 minutes or less, and most preferably 5 minutes or less. Within the above range, the fluororesin and the filler can be easily dispersed uniformly.

The volatile additive has the function of sufficiently containing pores in the composite material by finally volatilizing and removing it. The volatile additive means a compound having a boiling point of 30 to 300 ° C. and is liquid at room temperature (25 ° C.). The boiling point of the volatile additive is preferably 50 ° C. or higher, more preferably 100 ° C. or higher. It is more preferably 200 ° C. or higher, preferably 280 ° C. or lower, more preferably 260 ° C. or lower, still more preferably 240 ° C. or lower.

Examples of the type of volatile additive include hydrocarbons having low reactivity, ethers, esters, alcohols and the like, but aliphatic saturated hydrocarbons are preferable. Specifically, hexane (boiling point: 69 ° C), heptane (boiling point: 98 ° C), octane (boiling point: 126 ° C), nonan (boiling point: 151 ° C), decan (boiling point: 174 ° C), undecane (boiling point: 196 ° C). ), Dodecane (boiling point: 215 ° C.), tridecane (boiling point: 234 ° C.), tetradecane (boiling point: 254 ° C.), and the like. These can be used alone or in combination of two or more.

The amount of the volatile additive added is usually 1 part by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 10 parts by mass or more, when the total of the fluororesin and the filler is 100 parts by mass. 20 parts by mass or more, particularly preferably 30 parts by mass or more, usually 200 parts by mass or less, preferably 150 parts by mass or less, more preferably 130 parts by mass or less, still more preferably 110 parts by mass or less, particularly preferably 100 parts by mass. It is as follows. Within the above range, a good porosity can be ensured as a composite material.

In the mixing step, it is preferable to add a solvent in addition to the fluororesin, the filler, and the volatile additive to mix. The solvent has the function of making the precursor composition into a paste and uniformly dispersing it. Examples of the solvent include water, lower alcohols such as methanol, ethanol, isopropanol and butanol, and the like. These can be used alone or in combination of two or more.

The molding step is a step of molding the precursor composition to obtain a rollable object to be rolled. The molding machine used in the molding step includes an FT die (fishtail extrusion die), a press machine, and an extrusion molding machine. , Calendar roll, etc. FT dice are particularly preferable.

The rolling process is a process of rolling an object to be rolled to obtain a composite material, but it may be a "multi-step rolling" in which the work of laminating the obtained rolled objects and rolling them as an object to be rolled is repeated a plurality of times. It is particularly preferable that the "multi-step rolling in different directions" is performed in which the object to be rolled is rolled in a direction different from the previous rolling direction. In the different direction multi-step rolling, for example, the rolled products are laminated so as to face the same rolling direction to obtain a rolled product, and the rolling direction of the rolled product is rotated by 90 ° from the previous rolling direction to perform rolling. It can be repeated.

The number of layers of rolled products in multi-step rolling is usually 2 or more, preferably 3 or more, more preferably 4 or more, still more preferably 10 or more, particularly preferably 30 or more, and usually 2000 or less, preferably 1000 or less. It is preferably 700 or less, more preferably 500 or less, and particularly preferably 300 or less.

The rolling ratio of the rolling step is usually 10 or more, preferably 20 or more, more preferably 40 or more, further preferably 50 or more, particularly preferably 100 or more, and usually 20000 or less, preferably 15000 or less, more preferably 10000 or less. , More preferably 5000 or less, and particularly preferably 3000 or less.

Examples of the apparatus used in the rolling process include a press machine, an extrusion molding machine, a rolling roll (for example, a calender roll) and the like.

The method for producing the composite material or the method for producing the substrate may include other steps, and specific examples thereof include the following steps.
-An additive removing step of removing the volatile additive from the rolled product (hereinafter, may be abbreviated as "additive removing step").
-A heat compression step of heating and compressing the rolled product (hereinafter, may be abbreviated as "heat compression step").
-A resin layer forming step of forming a resin layer containing a fluororesin on one side or both sides of the composite material (hereinafter, may be abbreviated as "resin layer forming step").
-Another layer forming step of forming a conductor layer on one side or both sides of the composite material (hereinafter, may be abbreviated as "conductor layer forming step").
-A patterning step of patterning the conductor layer (hereinafter, may be abbreviated as "patterning step").
Hereinafter, the "additive removal step", the "heat compression step", the "resin layer forming step", the "conductor layer forming step", the "patterning step" and the like will be described in detail.

The additive removing step is a step of removing the volatile additive from the rolled product, and usually, a method of heating the rolled product in a heating furnace that can be used for drying can be mentioned. The heating conditions can be appropriately selected according to the boiling point of the volatile additive and the like.

The heat compression step is a step of heating and compressing a rolled product, but usually, a method of heating and compressing using a press or the like can be mentioned. The heating and compression conditions can be appropriately selected, but it is preferable to uniformly apply pressure to the rolled product in-plane.

The resin layer forming step is a step of forming a resin containing a fluororesin on one side or both sides of a composite material, but the resin layer is formed by using a press machine or the like to form a resin film containing a fluororesin. Examples thereof include a method of applying heat and pressure to a composite material. By heating and pressurizing the resin film containing the fluorine-based resin, the fluorine-based resin permeates the composite material, effectively suppressing the peeling of the conductor layer, etc., and ensuring a good relative permittivity as the composite material. it can.
The thickness of the resin film containing the fluororesin is usually 0.050 μm or more, preferably 0.10 μm or more, more preferably 0.40 μm or more, still more preferably 1.0 μm or more, and particularly preferably 1.5 μm or more. It is usually 30 μm or less, preferably 20 μm or less, more preferably 10 μm or less, still more preferably 8.0 μm or less, particularly preferably 6.0 μm or less, and most preferably 5.0 μm or less.

The pressure in the resin layer forming step is usually 0.01 MPa or more, preferably 0.10 MPa or more, more preferably 0.50 MPa or more, still more preferably 0.80 MPa or more, particularly preferably 1.00 MPa or more, and usually 50 MPa or less. It is preferably 40 MPa or less, more preferably 30 MPa or less, still more preferably 20 MPa or less, and particularly preferably 10 MPa or less. Within the above range, peeling of the conductor layer or the like can be effectively suppressed, and a good relative permittivity or the like can be secured as a composite material.

The temperature in the resin layer forming step is usually 250 ° C. or higher, preferably 280 ° C. or higher, more preferably 300 ° C. or higher, further preferably 320 ° C. or higher, particularly preferably 340 ° C. or higher, and usually 500 ° C. or lower, preferably 480 ° C. or higher. ℃ or less, more preferably 460 ° C or less, still more preferably 440 ° C or less, and particularly preferably 420 ° C or less. Within the above range, peeling of the conductor layer or the like can be effectively suppressed, and a good relative permittivity or the like can be secured as a composite material.

The heating and pressurizing time in the resin layer forming step is usually 1 second or longer, preferably 30 seconds or longer, more preferably 1 minute or longer, further preferably 2 minutes or longer, particularly preferably 3 minutes or longer, and usually 180 minutes or shorter. It is preferably 120 minutes or less, more preferably 60 minutes or less, still more preferably 30 minutes or less, and particularly preferably 20 minutes or less. Within the above range, peeling of the conductor layer or the like can be effectively suppressed, and a good relative permittivity or the like can be secured as a composite material.

Examples of the device used in the resin layer forming process include a press machine, a thermal roll laminating machine, and a belt press machine.

The conductor layer forming step is a step of forming a conductor layer on one side or both sides of the composite material, and examples of the conductor layer forming method include sputtering, plating, pressure bonding of metal foil, and laminating method. ..

The patterning step is a step of patterning a metal layer, and examples of the patterning process include an additive method using a photoresist and the like, a subtractive method by etching, and the like.

The present invention will be described in more detail with reference to examples below, but the present invention can be appropriately modified as long as it does not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limited by the specific examples shown below.

<Example 1>
As an inorganic fine particle aggregate, hydrophilic fumed silica (manufactured by Nippon Aerosil Co., Ltd., product number "AEROSIL50", BET specific surface area 50 ± 15 m ² / g, average primary particle size 40 nm, average particle size 0.2 μm of secondary aggregate) is used. As a surface modifier, triethoxy-1H, 1H, 2H, 2H-tridecafluoro-n-octylsilane (manufactured by Tokyo Chemical Industry Co., Ltd., product number "T1770") was used for modification.

Specifically, 40.8 g of a surface modifier, 22.1 g of acetic acid, 43.2 g of pure water, and 80 g of inorganic fine particle aggregates were added to 832.9 g of isopropanol, and the mixture was stirred for 24 hours to stir the inorganic fine particle aggregates. The dispersion liquid of was obtained. Next, the dispersion was heated at 100 ° C. for 1 hour and then at 200 ° C. for 2 hours to obtain surface-modified inorganic fine particle aggregates.

Next, fused silica (manufactured by Denka Co., Ltd., product number "SFP-130MC", BET specific surface area 6.2 m ² / g, average primary particle diameter 0.6 μm) was used as a non-porous inorganic fine particle, and triethoxy- was also used as a surface modifier. It was modified with 1H, 1H, 2H, 2H-tridecafluoro-n-octylsilane (manufactured by Tokyo Chemical Industry Co., Ltd., product number "T1770").

Specifically, to 83.3 g of isopropanol, 6.8 g of a surface modifier, 2.1 g of acetic acid, 4.3 g of pure water, and 80 g of non-porous inorganic fine particles were added, and the mixture was stirred for 24 hours to be non-porous. A dispersion of inorganic fine particles was obtained. Next, the dispersion was heated at 100 ° C. for 1 hour and then at 200 ° C. for 2 hours to obtain surface-modified non-porous inorganic fine particles.

Next, using a high-speed flow mixer, polytetrafluoroethylene (hereinafter, may be abbreviated as "PTFE"), inorganic fine particle aggregates, non-porous inorganic fine particles, and volatile additives were mixed. Specifically, polytetrafluoroethylene (manufactured by Daikin Co., Ltd., product number "Polyflon PTFE F-104", average particle size 550 μm) was prepared, and in consideration of the solid content, polytetrafluoroethylene and surface-modified inorganic fine particle coagulation were prepared. The aggregate and the non-porous inorganic fine particles are added so as to have a mass ratio of 44:46:10, and after stirring and mixing at a rotation speed of 14 m / sec and a temperature of 24 ° C. for 1 minute, hydrocarbon oil (Exxon Mobile) is used as a volatile additive. (Manufactured by the company, product number "Isoper M") is added so that the total of polytetrafluoroethylene, inorganic fine particle aggregates and non-porous inorganic fine particles is 65 parts by mass, and the rotation speed is 3 m / sec. , The mixture was mixed at a temperature of 24 ° C. for 5 minutes to obtain a paste.

The paste was passed through a pair of rolling rolls to form an elliptical mother sheet (sheet-shaped molded product) having a thickness of 3 mm, a width of 10 to 50 mm, and a length of 150 mm, and a plurality of the mother sheets were prepared. Next, two sheets of the mother sheet were laminated in the same rolling direction, and the laminate was passed between the rolling rolls in the same rolling direction and rolled to prepare a plurality of first rolled laminated sheets. Next, the four first rolled laminated sheets were laminated in the same rolling direction, and rolled in the same direction to prepare a second rolled laminated sheet. In this way, the step of laminating and rolling the sheets was repeated a total of 5 times counting from the laminating and rolling of the mother sheet to produce a third rolled laminated sheet (the number of constituent layers 512). Next, four third rolled laminated sheets are laminated, and the laminated sheets are rotated 90 degrees from the previous rolling direction while keeping the sheet surfaces parallel, and the laminated sheets are passed between the rolling rolls to be rolled, and a gap between the rolling rolls is formed. The sheet was narrowed by 0.5 mm and rolled a plurality of times to obtain a sheet having a thickness of about 0.18 mm. The obtained rolled laminated sheet was heated at 150 ° C. for 20 minutes to remove volatile additives, and a sheet-like composite material was prepared.

Next, Fluon (registered trademark) PTFE dispersion AD939E (manufactured by AGC, solid content 60% by mass) was dip-coated on one side of the polyimide carrier so that the WET thickness was 4 μm, and 380 for 5 minutes at 150 ° C. A resin film to be a resin layer was prepared by heating at ° C. for 5 minutes. By preparing a Cu foil (JX Nippon Mining & Metals Co., Ltd., product number "BHFX-HS-92F") as a conductor layer, laminating a resin film and a Cu foil, and pressurizing with a press machine at a pressure of 6 MPa and a temperature of 360 ° C. for 10 minutes. A resin conductor sheet was produced. This resin conductor sheet and the above-mentioned sheet-shaped composite material were laminated and pressure-molded at 360 ° C. for 5 minutes at 4 MPa to prepare a laminated sheet with the conductor layer. With respect to the obtained laminated sheet, the peeling strength of the plate-shaped composite material and the resin conductor sheet, which will be described later, was measured. Next, the obtained laminated sheet was immersed in a 38% by mass second aqueous solution of iron chloride (manufactured by Sanhayato Co., Ltd., etching solution H-200A) for 30 minutes to remove the conductor layer, washed with pure water, and dried. A plate-shaped composite material was obtained.

<Example 2>
Same as in Example 1 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 44:28:28 during mixing with a high-speed flow mixer. A composite material was obtained by the method.

<Example 3>
The same method as in Example 1 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates, and non-porous inorganic fine particles were added so as to have a mass ratio of 44:15:41 during mixing with a V-type mixer. Obtained a composite material.

<Example 4>
As the non-porous inorganic fine particles, Kojilite powder (FINE type manufactured by AGC Ceramics Co., Ltd.) and an average particle diameter of 25 μm are used, and when mixed with a high-speed flow type mixer, polytetrafluoroethylene and surface-modified inorganic fine particle aggregates and no pores are formed. The mass ratio of the quality inorganic fine particles is 44:30:26, and the volatile additive is 50 mass when the total of polytetrafluoroethylene, inorganic fine particle aggregates and non-porous inorganic fine particles is 100 parts by mass. A composite material was obtained by the same method as in Example 1 except that the particles were added in portions.

<Example 5>
Same as in Example 1 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 38:28:34 during mixing with a high-speed flow mixer. A composite material was obtained by the method.

<Example 6>
Similar to Example 1 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 34:28:38 when mixed with a high-speed flow mixer. A composite material was obtained by the method.

<Example 7>
Similar to Example 1 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 30:28:42 when mixed with a high-speed flow mixer. A composite material was obtained by the method.

<Example 8>
Similar to Example 1 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 26:28:46 when mixed with a high-speed flow mixer. A composite material was obtained by the method.

<Comparative example 1>
Similar to Example 1 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 60:40: 0 when mixing with a high-speed flow mixer. A composite material was obtained by the method.

<Comparative example 2>
When mixed with a high-speed flow mixer, polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 40:60: 0, and a volatile additive was added as polytetrafluoro. A composite material was obtained by the same method as in Example 1 except that ethylene, inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to be 100 parts by mass when the total was 100 parts by mass.

<Comparative example 3>
When mixed with a high-speed flow mixer, polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 20:80: 0, and a volatile additive was added as polytetrafluoro. A composite material was obtained by the same method as in Example 1 except that ethylene, inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to be 150 parts by mass when the total was 100 parts by mass.

<Comparative example 4>
When mixed with a high-speed flow mixer, polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 60: 0: 40, and a volatile additive was added as polytetrafluoro. A composite material was obtained by the same method as in Example 1 except that ethylene, inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to be 45 parts by mass when the total was 100 parts by mass.

<Comparative example 5>
Similar to Comparative Example 4 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 40: 0: 60 during mixing with a high-speed flow mixer. A composite material was obtained by the method.

<Comparative Example 6>
Similar to Comparative Example 4 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 20: 0: 80 during mixing with a high-speed flow mixer. A composite material was obtained by the method.

<Comparative Example 7>
Same as in Example 1 except that polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 44:50: 6 during mixing with a high-speed flow mixer. A composite material was obtained by the method.

<Comparative Example 8>
As the non-porous inorganic fine particles, Kojilite powder (FINE type manufactured by AGC Ceramics Co., Ltd.) and an average particle diameter of 25 μm are used, and when mixed with a high-speed flow type mixer, polytetrafluoroethylene and surface-modified inorganic fine particle aggregates and no pores are formed. The mass ratio of the quality inorganic fine particles is 44: 0: 56, and the volatile additive is 30 mass when the total of polytetrafluoroethylene, inorganic fine particle aggregates and non-porous inorganic fine particles is 100 parts by mass. A composite material was obtained by the same method as in Example 1 except that the particles were added in portions.

<Comparative Example 9>
When mixed with a high-speed flow mixer, polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 70:30: 0, and a volatile additive was added as polytetrafluoro. A composite material was obtained by the same method as in Example 1 except that ethylene, inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to be 54 parts by mass when the total was 100 parts by mass.

<Comparative Example 10>
When mixed with a high-speed flow mixer, polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 50:50: 0, and a volatile additive was added as polytetrafluoro. A composite material was obtained by the same method as in Example 1 except that ethylene, inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to be 82 parts by mass when the total was 100 parts by mass.

<Comparative Example 11>
When mixed with a high-speed flow mixer, polytetrafluoroethylene, surface-modified inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to have a mass ratio of 30:70: 0, and a volatile additive was added as polytetrafluoro. A composite material was obtained by the same method as in Example 1 except that ethylene, inorganic fine particle aggregates and non-porous inorganic fine particles were added so as to be 122 parts by mass when the total was 100 parts by mass.

For each of the obtained plate-shaped composite materials, the porosity, peeling strength, relative permittivity / dielectric loss tangent, tensile strength / tensile elastic modulus, and coefficient of thermal expansion were measured as follows. The results are shown in Tables 1 to 3.

<Porosity>
Volume of composite material, specific gravity and mass of polytetrafluoroethylene (PTFE) (blending mass), specific gravity and mass of inorganic fine particle aggregates (blending mass), specific gravity and mass of non-porous inorganic fine particles (blending mass), etc. It was calculated by measuring the specific gravity and mass (blending mass) of the filler and substituting it into the following formula.
[Pore ratio (%)] = ([Volume of composite material]-[Mass of PTFE / Specific gravity of PTFE]-[Mass of inorganic fine particle aggregates / Specific gravity of inorganic fine particle aggregates]-[Mass of non-porous inorganic fine particles] / Specific gravity of non-porous inorganic fine particles]-[Mass of other fillers / Specific gravity of other fillers]) / [Volume of composite material] x 100

<Peeling strength>
For each of the composite materials of Examples 1 to 8 and Comparative Examples 1 to 11, a copper-clad laminate test for a printed wiring board conforming to Japanese Industrial Standards JIS C6481: 1996 was carried out. A test piece having a length of about 100 mm was prepared with the conductor layer laminated to a width of 10 mm, and the average value of the load when the conductor layer portion was peeled off at a speed of 50 mm / min in the direction of 90 ° was peeled off. Measured as strength.

<Relative permittivity / dielectric loss tangent>
The measurement frequency was set to 10 GHz, the complex permittivity was measured by the cavity resonator perturbation method, and the real part (εr') of the complex permittivity was taken as the relative permittivity. Further, the dielectric loss tangent was obtained from the ratio (εr ″ / εr') of the real part and the imaginary part (εr ″).
Using a relative permittivity measuring device (“Network Analyzer N5230C” manufactured by Agilent Technologies and “Cavity Resonator 10 GHz” manufactured by Kanto Electronics Applied Development Co., Ltd.), a strip-shaped sample (sample size width 2 mm × length 70 mm) was used from each sheet. ) Was cut out and measured.

<Tensile strength / modulus of elasticity>
The tensile strength (tensile breaking strength) and tensile elastic modulus of the plate-shaped composite material were measured according to the method specified in Japanese Industrial Standard JIS K7161. More specifically, a desktop precision universal testing machine Autograph AGS-X (manufactured by Shimadzu Corporation) is used as a tensile testing machine to measure a measurement temperature of 25 ° C., a tensile speed of 100 mm / min, and an initial distance between gripping tools of 10 mm. Under the conditions, a tensile test was carried out in the longitudinal direction (MD direction) of the dumbbell-shaped No. 1 type or dumbbell-shaped No. 2 type (width of the parallel portion 10 mm). Then, the maximum tensile force recorded before the test piece is cut is obtained, and the value obtained by dividing this by the cross-sectional area of the test piece is defined as the tensile strength (unit: MPa), which is 0.05% at the time of the tensile test. The tensile elastic modulus (unit: GPa) was defined as the slope of the stress / strain curve corresponding between the two points of 0.25% strain.

<Coefficient of thermal expansion>
The average coefficient of linear thermal expansion of −50 ° C. to 200 ° C. was adopted as the coefficient of thermal expansion, and the calculation was performed using the TMA (Thermal Mechanical Analysis) method.
Using a thermomechanical analyzer (“TMA4000SA” manufactured by BRUKER AXS), a composite material having a width of 4 mm and a length of 20 mm was fixed in the length direction and a load of 2 g was applied. The residual stress of the material was removed by raising the temperature from room temperature to 200 ° C. at a heating rate of 10 ° C./min and holding for 30 minutes. Then, the mixture was cooled to −50 ° C. at 10 ° C./min, held for 15 minutes, and then heated to 200 ° C. at 2 ° C./min. The average coefficient of linear thermal expansion of −50 ° C. to 200 ° C. in the second heating process was defined as the coefficient of thermal expansion.

Graphs showing the relationship between the total filler content and the dielectric loss tangent of the composite materials of Examples 5 to 8 and Comparative Examples 2 to 3 and 10 to 11 are shown in FIG. FIG. 3 shows a graph showing the relationship between the total filler content of the composite materials 9 to 11 and the coefficient of thermal expansion. From the graph of FIG. 2, when the filler is a porous inorganic fine particle aggregate alone such as fumed silica, the dielectric loss tangent increases as the content of the filler increases, and the filler is like molten silica. It is clear that it can be remarkably suppressed by blending non-porous inorganic fine particles. Further, from the graph of FIG. 3, it is clear that the increase in the coefficient of thermal expansion accompanying the decrease in the content of the porous inorganic fine particle aggregates can be suppressed by an appropriate blending of the non-porous inorganic fine particles. That is, it can be said that the plate-shaped composite material in which the porous inorganic fine particle agglomerates and the non-porous inorganic fine particles are appropriately mixed is an excellent material that is harmonious in terms of various properties.

Although the specific embodiment of the present invention has been shown in the above-described embodiment, the above-mentioned embodiment is merely an example and is not interpreted in a limited manner. Various variations apparent to those skilled in the art are intended to be within the scope of the present invention.

The composite material according to one aspect of the present invention can be used as a circuit board for mobile phones, computers, etc., a substrate for a microstrip patch antenna for millimeter-wave radar, and the like.

Claims

A plate-shaped composite material containing a fluororesin and a filler.
The filler contains a porous inorganic fine particle agglomerate formed by aggregating inorganic fine particles having an average primary particle diameter of 5 to 200 nm, and a non-porous inorganic fine particle having an average primary particle diameter of 0.2 to 50 μm.
The total content of the porous inorganic fine particle aggregate and the non-porous inorganic fine particle is 20 to 90% by mass of the composite material, and the total content of the porous inorganic fine particle agglomerate and the non-porous inorganic fine particle is 20 to 90% by mass. The mass ratio of the content of the non-porous inorganic fine particles to the mass ratio (content of the non-porous inorganic fine particles / (content of the porous inorganic fine particle aggregate + content of the non-porous inorganic fine particles)) is 0. A plate-shaped composite material characterized by being .15 to 0.90.
The plate-shaped composite material according to claim 1, which has a porosity of 15% by volume or more.