JP2001164124A - Resin composite, and electric wave absorber using the same and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent resin composite which can be adaptable to downsizing and wt. reduction and has such characteristics as to realize the characteristics of various fillers to the maximum. SOLUTION: This resin composite contains 25-95 vol.% at least one material selected from among magnetic materials, inorganic materials, and carbonaceous materials dispersed therein, and the relative density of the composite is 70% or higher of the theoretical density.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to structural parts, sliding parts, mechanical parts, automobile parts, OA equipment parts, electronic parts,
Also, the present invention relates to a resin composite used for a measure against unnecessary radiation of an antenna, a measure against a radio ghost, a measure against an anechoic chamber, a noise countermeasure component of digital information equipment, a radio wave absorber used for a building wall material, a tile, and the like.

[0002]

2. Description of the Related Art Conventionally, metal materials and ceramic materials have been frequently used for electronic parts, structural parts, mechanical parts and the like. .

In general, characteristics required for materials forming such various components include required characteristics for each component such as heat resistance, dimensional stability, electric characteristics, magnetic characteristics, and the like. A resin composite material has attracted attention as a device having the above.

[0004] This resin composite is constituted by blending fillers such as wood powder, talc, glass, and inorganic powder in a predetermined ratio, and has a heat resistance, a dimensional stability, and the like with respect to a resin alone. Therefore, it has been spotlighted as being suitable for various electronic components and structural components.

Further, a magnetic material is dispersed and contained in an insulator,
A radio wave absorber that removes unnecessary waves by attenuating radio waves using the magnetic loss is known.

[0006] A radio wave absorber that absorbs an incident radio wave absorbing layer and converts radio wave energy into heat energy causes unnecessary reflection, scattering, and interference of radio waves in buildings, facilities, equipment, and its surroundings. Various troubles can be suppressed by mounting at the place where the trouble occurs.

[0007] Such a resin composite is usually
It is manufactured by injection molding, that is, by injecting a resin slurry into a predetermined mold and solidifying it by heating or cooling.

Further, as a material constituting the radio wave absorber, a composite material in which a magnetic material is blended in a predetermined ratio in rubber, a thermoplastic resin, or a thermosetting resin is used (JP-A-10-74611). JP-A-5-27060 and JP-A-4-213803), such a resin composite and a radio wave absorber using the same are usually prepared by injecting a resin slurry into a predetermined mold. It has been produced by an injection molding method in which it is cured by heating or solidification by cooling, injection molding, extrusion molding, blow molding, compression molding, transfer molding, cast molding, non-stretched film processing, stretched film processing, or the like.

[0009]

When a resin composite is used for a radio wave absorber, if the mixing ratio of the conductive magnetic material as the filler is increased, the electric resistivity is reduced due to the contact between the fillers. However, there is a problem that the amount of radio wave reflection increases.

Therefore, in order to obtain a high electric resistivity, a radio wave absorber is manufactured using a flaky or flaky magnetic material whose powder thickness is flattened to the skin depth.

However, when the conventional resin composite is molded by the above-described injection molding method or the like, it is necessary to make the resin slurry in a molten state at the time of molding and to have a certain fluidity, and to improve the moldability. When emphasis is placed, the amount of the filler added is limited to a certain amount or less, and uniform dispersion is difficult. In particular, the filling limit is also significantly restricted by the shape of the filler, and high filling and uniform dispersion of the filling amount cannot be expected in shapes such as flakes and flakes. Therefore, the radio wave absorber has a problem that it is difficult to adjust the complex relative magnetic permeability and the complex relative permittivity, which are influenced by the mixing ratio of the magnetic material.

Further, in these methods, since the resin is molded in a molten state, the filler is oriented in the flow direction of the resin, and there is a problem that characteristics such as mechanical strength and anisotropy in dimensional accuracy occur. there were.

In order to solve the above-mentioned problems, the present inventors have proposed a novel resin composite in which the compounding ratio of the filler is increased by employing a conventionally well-known powder pressure molding method. (Japanese Patent Application No. 9-329232). Since such a resin composite is molded using the resin component and the filler as powder, restrictions on the amount of the filler are relatively loose, and the amount of the filler can be increased. Magnetic properties such as electrical characteristics (withstand voltage, tracking resistance, dielectric loss, etc.), thermal characteristics (thermal conductivity, coefficient of thermal expansion), and magnetic permeability can be greatly improved.

However, if a large amount of a filler having a large specific gravity, such as a ceramic material or a magnetic material used as a magnetic material, or a ferrite material, which is a typical inorganic filler, is blended in a large amount, the specific gravity of the resin composite material becomes large.
There is a problem that the lightness required for the resin material is impaired. Therefore, when a porous structure is formed by using a foamed material or the like for the resin composite material, the mechanical strength is significantly reduced, so that the thickness and volume of the entire molded body must be increased, and miniaturization becomes difficult. However, there is a problem that the dimensional accuracy is deteriorated.

[0015]

The inventor of the present invention has conducted intensive studies in order to solve the above-mentioned problems. As a result, at least one of a magnetic material, an inorganic material, and a carbon-based material was added to a synthetic resin in an amount of 25 to 50%. By using a resin composite composed of a composite material having a uniform dispersion content of 95% by volume and having a relative density of 70% or more of the theoretical density, it is possible to produce a complex shape, It is intended to improve the target strength. The filler has an average aspect ratio of 1 or more and 10 or less, an average particle size of 1 μm or more and 300 μm or less, and a maximum particle size of 50 or less.
By setting the thickness to 0 μm or less, the resin can be highly filled and uniformly dispersed. As a result, a resin composite which can have desired properties such as electric properties, thermal properties, and magnetic properties by selecting various fillers. Was obtained. In addition, by suppressing the orientation of the filler, it is possible to reduce the anisotropy of properties such as mechanical strength and dimensional accuracy, and to increase the relative density of the main surface compared to the internal relative density. Accordingly, the present invention provides a resin composite having excellent dimensional accuracy, which can improve the mechanical strength and can be reduced in size and thickness.

Further, by using a radio wave absorber having a different relative density depending on the portion, a radio wave absorber capable of realizing a wide band even if the thickness is reduced can be obtained.

[0017]

Embodiments of the present invention will be described below in detail.

The resin composite of the present invention contains at least one filler of at least one magnetic material, inorganic material or carbon material dispersed in a synthetic resin in an amount of 25 to 95% by volume and has a relative density of 70% or more of the theoretical density. Things. As a method for producing this resin composite, for example, a synthetic resin, a magnetic material, an inorganic material,
A composite material containing 25 to 95% by volume of at least one filler of a carbon-based material dispersed therein is granulated to a predetermined particle size, molded by a powder pressure molding method, released from a mold, and heated at a predetermined temperature for a predetermined time. The relative density can be increased to 70% or more by allowing the curing gas to proceed from the surface of the molded body and trapping the reaction gas generated inside the molded body inside the molded body, and the filler is oriented in a specific direction. An excellent molded article free of the above can be produced. Hereinafter, a magnetic material, an inorganic material, and a carbon-based material may be referred to as a filler. Here, at least one of the magnetic material, the inorganic material, and the carbon-based material to be mixed with the synthetic resin is set to 25 to 95% by volume.
This is because deformation such as sagging and swelling occurs after heat curing, and the shape cannot be retained. For example, when molding is performed by a generally known resin molding method other than the above, problems such as deformation of the molded body such as sagging and swelling as described above can be avoided, but on the other hand, the flowability of the resin is reduced, so that the filling is performed. There have been problems such as the inability to perform high filling of the material or the occurrence of anisotropy in mechanical strength due to the orientation of the filler in the flow direction of the resin.

Conversely, if the amount of the magnetic material, inorganic material, or carbon-based material is more than 95% by volume, the surface of the filler cannot be uniformly coated with the resin, and the strength is significantly reduced.

The volume% of the resin or each filler is;
v _1, v _2, v ₃ calculated for ... (%) is, the mixing weight w (g), respectively specific gravity D w ₁ of the resin or filler,
_{w 2, w 3 ···, D} 1, D 2, D 3 ··· (g / cm 3) to to be able to calculate the following formula. v ₁ (%) = (w ₁ / D ₁ ) / (w ₁ / D ₁ + w ₂ / D ₂ + w ₃
/ D ₃ +...) × 100 Further, in the present invention, it is important that the relative density is 70% or more of the theoretical density. In a resin composite material, when a material having a large specific gravity is used as a filler, the relative density is reduced with a foamed resin or the like for the purpose of weight reduction. However, if the relative density of the resin composite is too low, the mechanical strength is reduced, so that the thickness and volume of the entire molded body made of the resin composite must be increased, and miniaturization can be realized. Absent.

Therefore, the relative density of the composite material is 70
% Or more, preferably 85% or more, and within these ranges, the molded body made of the resin composite can maintain high strength.

Further, a radio wave absorber can be obtained by including a magnetic material composed of an iron group metal containing at least one of a soft magnetic metal material and ferrite or a compound thereof in the filler of the present resin composite. it can. In this case, attention was paid to the fact that when the relative density of the composite material becomes small, its complex relative magnetic permeability and complex relative permittivity decrease, and the applied frequency of the radio wave absorber shifts to the high frequency side and the band is widened. However, in this case, if the relative density is less than 70%, the complex relative magnetic permeability and the complex relative permittivity decrease, and it is necessary to increase the thickness of the radio wave absorber.

For this reason, when used in a radio wave absorber, it is important that the relative density is 70% or more, preferably 90% or more.
It has excellent radio wave absorption characteristics of 20 dB or more for almost all radio waves in the frequency band of 0 GHz.

Examples of the synthetic resin constituting such a resin composite include epoxy resin, phenol resin, melamine resin, urea resin, unsaturated polyester resin, polyimide resin, furan resin, polybutadiene resin, ionomer resin, and EEA resin. , AAS resin (ASA resin), AS resin, ACS resin, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer resin, ABS resin, vinyl chloride resin,
Chlorinated polyethylene resin, cellulose acetate resin, fluorine resin, polyacetal resin, polyamide resin 6,66, polyamide resin 11,12, polyarylate resin, thermoplastic polyurethane elastomer, liquid crystal polymer, polyetheretherketone, polysulfone resin, polyether Sulfone resin, high density polyethylene, low density polyethylene,
Resins such as linear low-density polyethylene, polyethylene terephthalate, polycarbonate resin, polystyrene resin, polyphenylene ether resin, polyphenylene sulfide resin, polybutadiene resin, polypropylene resin, methacrylic resin and methylpentene polymer can be used. Phenolic resins are preferred in terms of properties, dimensional stability, strength, price, and the like.

When a material such as synthetic rubber having a very low thermal conductivity is selected as the matrix, the difference in shrinkage during heat curing between the inside and the surface of the molded article is significantly different, so that after the heat curing, the mold after demolding is formed. The material of the present invention is not suitable as the material of the present invention because it is deformed, the dimensional accuracy is deteriorated, and the deterioration due to aging is remarkable, and the long-term reliability is lacking.

On the other hand, the magnetic material constituting the filler of the resin composite is preferably a metal of iron group containing at least one of a soft magnetic metal material and ferrite or a compound thereof. As the soft magnetic metal material, for example, if it is an amorphous magnetic metal alloy, an Fe-B-Si system,
Fe-B-Si-C system, Fe-B-Si-Cr system, Fe
-Co-B-Si system, Fe-Ni-Mo-B system, Co-
Fe-Ni-Mo-B-Si system, Co-Fe-Ni-B
-Ni-Fe based alloys such as -Si based, such as 36-permalloy, 45-permalloy, [mu] -metal, 78-permalloy, Cr-permalloy, Mo-permalloy, supermalloy, etc., pure iron, mild steel, Fe- Si alloys, Fe-Al
Alloys, Fe-Si-Al alloys, Co-Fe alloys, and carbonyl iron. As ferrite, for example, M
n-Zn ferrite, Ni-Zn ferrite, Cu
-Zn ferrite, Cu-Zn-Mg ferrite, M
n-Mg-Al ferrite, Y-type hexagonal ferrite, Z
Type hexagonal ferrite and M type hexagonal ferrite.

It should be noted that each magnetic material has a very high specific gravity, and when it is made into a composite material, it is necessary to control the compounding with other fillers having a small specific gravity or the relative density thereof in order to realize a reduction in size and weight. is there.

It is known that the shape of the above magnetic material has a significant effect on the magnetic loss of the radio wave absorber. If the magnetic material is in the form of scales, flakes, flakes, needles, or fibers, Although there is an advantage that the magnetic loss is increased, a decrease in electric resistivity due to high filling is unavoidable, and uniform dispersion is extremely difficult.

As the inorganic material constituting the filler, alumina, silica, diatomaceous earth, zinc oxide, tetrapot type zinc oxide, titanium oxide, calcium oxide, magnesium oxide, tin oxide, antimony oxide, calcium hydroxide, water Magnesium oxide, acicular magnesium hydroxide, aluminum hydroxide, plate-like aluminum hydroxide, basic magnesium carbonate, calcium carbonate, magnesium carbonate,
Zinc carbonate, barium carbonate, dawsonite, hydrotalcite, calcium sulfate, barium sulfate, gypsum, gypsum fiber, calcium silicate, talc, clay, mica, montmorillonite, bentonite, activated clay, sepiolite, imogolite, serisarit, glass fiber, glass Beads, glass flakes, glass balloons, silica balloons, shirasu balloons, aluminum nitride, boron nitride,
Silicon nitride, potassium titanate, zirconate titanate, aluminum borate, molybdenum sulfide, zinc borate, slag fiber, barium titanate, zirconia, boron nitride, silicon carbide, asbestos, barium titanate,
Zircon tin titanium, Ba-rare earth-Ti oxide, NdA
10 ₃ -CaTiO ₃ , LaAlO ₃ -SrTiO ₃ , Ba
(Zn _1/2 Ta _1/2 ) O ₃ , BaTi ₄ O ₉ , Li-rare earth-
Ti oxide, various ceramic whiskers, etc. can be used according to required characteristics.

As the carbon-based material constituting the filler, PAN-based carbon fiber, pitch-based carbon fiber, rayon-based carbon fiber, phenol-based carbon fiber, graphite whisker, flaky natural graphite, flaky natural graphite, earth-like graphite Natural graphite, artificial graphite and the like can be suitably used.

In the present invention, the average aspect ratio of the filler is from 1 to 10, preferably from 1.1 to 5.
By setting the content as described below, it is possible to obtain a material having high mechanical strength and excellent in various required characteristics and dimensional accuracy. However, when the average aspect ratio is larger than 10, when the filler is compounded in a large amount of 25 to 95% by volume and mixed with the synthetic resin, uniform dispersion becomes difficult and molding becomes difficult.

By observing the cross section or surface of the composite material of the present invention with a backscattered electron image using a wavelength-dispersive X-ray microanalyzer, particles containing the elements constituting the filler can be specified.

The content of the filler is determined by image analysis of a photograph of the backscattered electron image or by tracing the photograph, measuring the area occupancy of the filler in the photograph, and calculating the area occupancy by the content of the filler. Is defined. In the case of image analysis, it is necessary to prevent the filler from being affected by deformation, grain fall, and the like. The average aspect ratio of the filler is determined by taking an image of an arbitrary cross section of the particle with a scanning electron microscope, measuring the long side and short side dimensions of the particle by image analysis from the image, and measuring the long side / short side. It is obtained by calculating the side. The average particle diameter can be obtained by measuring the left, right, top and bottom dimensions of the image of each particle and calculating the average value.

The filler has an average particle size of 1 μm or more and 30 μm or more.
The thickness is preferably 0 μm or less, more preferably 3 μm or more and 20 μm or less. This is because if the average particle size is smaller than 1 μm, the pulverization cost is increased and it is not economically suitable, and if the average particle size is larger than 300 μm, the dispersibility at the time of mixing with the resin is poor. This is because, at the same time, it cannot be sufficiently maintained, and at the time of mold release after powder pressure molding, chipping and cracking are likely to occur.

The maximum particle size of the filler is preferably 500 μm or less, more preferably 300 μm or less.
The maximum particle size of the filler exceeds 500 μm, and the dispersibility at the time of mixing with the resin is poor, so that the strength cannot be sufficiently maintained, and at the same time, chipping and cracking occur at the time of mold release after powder pressure molding described later. Is likely to occur.

The maximum particle size of the filler is the length of the longest part when the left, right, top and bottom dimensions are measured. An arbitrary surface or cross section of the material is analyzed by an image analyzer, and the longest diameter of the largest filler among the powders present on the surface is defined as the maximum particle size.

When the average particle diameter of the filler is D,
It is preferable that 40% by volume or more of the filler is in the range of 0.1D to 10D. In order to obtain a resin composite in which the filler of the present invention is not oriented in a specific direction, it is necessary to granulate the composite in advance in terms of the production method. If the content is less than the volume%, for example, if a classification treatment for adjusting to a predetermined particle size is performed, a composition deviation occurs with respect to the prepared composition, and stable material properties cannot be obtained.

When the average particle diameter of the filler is D,
The content of the filler in the range of 0.1D to 10D is measured as follows. Image analysis of any cross section of the resin composite,
The area occupancy of the filler in the range of 0.1D to 10D is measured, and this area occupancy is defined as the content of the filler.

When a metal material or the like which is a conductive material is used as the magnetic material, if it is necessary to electrically cut off the particles, the surface of the magnetic material is oxidized or insulated in advance with a coupling agent or the like. It does not matter. Further, during the heat curing of the resin composite, the insulating layer may be formed on the surface of the magnetic material by using a synthetic resin that generates an acidic or alkaline gas that promotes corrosion of the metal.

Further, according to the resin composite of the present invention, it is important that the magnetic material, the inorganic material, and the carbon-based material are not oriented, that is, not oriented in a specific direction. Normally, in injection molding or casting molding, the orientation of the filler in the flow direction of the resin,
Transfer of the mold surface occurs. The orientation of the filler is particularly noticeable in flakes, needles, and fibrous fillers with a large aspect ratio, and the material properties from a specific surface are good,
In other aspects, there were problems such as a decrease in material properties, a decrease in mechanical strength, and a decrease in dimensional accuracy.

On the other hand, in the present invention, orientation can be eliminated by subjecting the granules blended at a predetermined ratio to cold powder pressing to solve these problems.

[0042] The above-mentioned filler is non-oriented, specifically, assuming that the angle of the major axis of the filler is within a range of 0 degree or more and less than 180 degrees with respect to one principal plane. It is preferable that the filler is present at a probability of 20 to 30% within the range of not less than 45 degrees and at a probability of 20 to 30% within the range of not less than 90 degrees and less than 135 degrees.

The orientation can be measured by analyzing a photograph of a backscattered electron image of an arbitrary cross section of the resin composite or tracing the photograph, and measuring an angle of the filler with respect to one major surface of a long axis of the filler on a photograph screen. Then, the probability that the filler exists in each range is calculated.

Further, in the resin composite of the present invention, by increasing the relative density of the main surface as compared with the relative density of the inside,
Even if the overall relative density is set to 70%, the mechanical strength can be improved. For example, as shown in FIG. 1, it is preferable that the relative density decreases continuously from the main surface 1 to the inside 2 of the resin composite 10.

In the cold powder press molding method, the distribution of the relative density can be controlled by adjusting the operating position of the mold. That is, as shown in FIG. 2, the difference in pressure propagation generated between the center and the periphery of the powder 4 filled in the mold is positively utilized. For example, when the lower punch 5 is fixed, the relative density of the obtained molded body can be continuously reduced from the upper surface to the lower surface by lowering the upper punch 6 to a predetermined position and raising the die 7 at the same time.
In addition, when heated and cured at normal pressure, gas generated by the vaporization and curing reaction of volatile components contained in the resin generates fine pores inside the molded body and remains inside the molded body, thereby increasing the relative density. Can be smaller.

The fine pores generated in the synthetic resin gradually move to the surface of the resin in the molten state during the heat curing, and the pores are reduced and disappear with the outgassing from the surface.
Therefore, the heat-cured body 8 obtained by heat-curing the molded body can continuously reduce the relative density from the surface of the molded body to the inside of the molded body. Alternatively, by mixing hollow bodies such as glass beads, shirasu balloons, and resin beads, the relative density of the resin composite can be reduced and the weight can be reduced.

As described above, by controlling the temperature during heating or preparing a composite material containing hollow bodies having different particle sizes, it is possible to control the distribution state of the relative density in the resin composite. it can. Further, from the viewpoint of maintaining the strength of the composite, the main surface, that is, the relative density of the surface layer portion of the composite material is 95% of the theoretical density.
% Or more, preferably 97% or more. When the relative density of the surface layer of the composite material is less than 95%, when the thickness of the resin composite is reduced, the strength is remarkably reduced, which is not practical.

In the present invention, the surface portion of the composite material means up to 10% of the outer dimension from the surface of the resin composite toward the center.

The relative density (%) is calculated by the following equation.

Relative density = (apparent density / theoretical density) × 100 The apparent density of the resin composite is measured by the Archimedes method. The theoretical density of the resin composite (g / g)
cm ³ ), when the true specific gravity of the synthetic resin and the fillers 1, 2, 3,... is known, the theoretical density of the resin composite is calculated by the following equation.

Theoretical density = W / V where W = (weight of synthetic resin / true specific gravity of synthetic resin) + (filler 1
Weight / filler 1 true specific gravity) + (filler 2 weight / filler 2 true specific gravity) + (filler 3 weight / filler 3 true specific gravity) + ... V = weight of synthetic resin + filler 1 weight + filling If the true specific gravity of the synthetic resin and the fillers 1, 2, 3,... Is unknown, the measurement is performed by the constant volume expansion method (He gas replacement method). (Based on JIS R1620).

When the resin composite of the present invention is used as a radio wave absorber, by having portions having different relative densities, the amount of the filler such as a magnetic material, an inorganic material, and a carbon-based material can be substantially reduced. It has substantially different portions, and can impart radio wave absorber characteristics over a wide band. For example, molded articles having different relative densities can be laminated and adhered to each other, or the relative density can be controlled depending on the operation position of the above-described mold. As shown in FIG. It is preferable that the size increases continuously from the surface 1 toward the inside.

That is, a gradient is given to the filling amount of the magnetic material, the inorganic filler and the carbon filler substantially by making the relative density having a certain distribution exist inside the radio wave absorber made of the resin composite 10. be able to. For example, by reducing the relative density of the radio wave incident surface and increasing the relative density toward the inside, the filling amount of a filler made of a magnetic material, an inorganic material, or a carbon-based material can be substantially reduced to the main radio wave incident surface. From inside to inside.

By using the resin composite of the present invention, various required characteristics can be imparted by the filler, and
By means of powder pressing, parts having complicated shapes can be provided relatively easily and at low cost. Therefore, in addition to safety equipment parts such as thermostat cases and thermal fuse cases that require high reliability, connectors, switches, support parts for various electronic components, OA equipment housings, board positioning,
Jigs used for cutting, etc., various sliding parts, especially when mounted as a radio wave absorber to cover the board or digital information equipment circuit or element as a case shape, or when used as a building member, Since the thermal conductivity can be controlled by adjusting the relative density, an effect as a heat insulating material can be expected in addition to the weight reduction, and it can be suitably used as a material for forming various parts and structural materials.

[0055]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. Example 1 A resin composite of the present invention is a synthetic resin as a raw material powder, a phenol resin (specific gravity: 1.1 g / cm ³ ) and a glass fiber having an average fiber length of 50 μm (specific gravity of 2.
2 g / cm ³ ) were prepared, weighed and mixed so as to have the compounding ratio shown in Table 1, and then the mixture was subjected to powder pressure molding at a normal temperature at a molding pressure of 0.5 to 8 ton / cm ² to form a mold. , And heat-cured at a temperature of 80 to 250 ° C. to obtain a test piece. The samples thus obtained were measured for relative density, three-point bending strength, and deflection temperature under load, and the results are shown in Table 1. In addition, about the deformation after heat curing,
When a shape defect such as sagging or swelling occurred, the result was x, and when the dimensional accuracy was poor at ± 0.5% or more, the condition was poor.
When no dimensional defect occurred, it was evaluated as ○.

According to Table 1, when the glass fiber content was less than 25% by volume (No. 1), it was not practical because the molded product could not be retained after heat curing.

When the glass fiber content exceeds 95% by volume (Nos. 2 and 3), cracks and chippings occur after the mold is released from the mold, and the yield and the dimensional accuracy are poor and practical. Did not.

When the relative density of the resin composite was less than 70% (No. 6, No. 7), the mechanical strength and the deflection temperature under load decreased, which was not practical.

On the other hand, when the content of glass fiber is 25 to
In the case of 95% by volume and the relative density in the range of 70% or more (No. 8 to No. 12), in all resin composites, the deflection temperature under load was 150 ° C. or more, the heat resistance was excellent, and the heat resistance was 50 MPa or more. Strength could be obtained.

[0060]

[Table 1]

Example 2 Next, a phenol resin (specific gravity: 1.1 g / cm) was used as the synthetic resin.
³ ) 30% by volume, 70% by volume permalloy (specific gravity: 7.9 g / cm ³ ) of a magnetic material is used as the filler, the relative density is 75%, the orientation of the filler, the aspect ratio, the average particle diameter D, 0 Nos. 1D to 10D, the resin composites having different content rates and maximum particle diameters of No. 15-No. No. 19 was manufactured by the same manufacturing method as in Example 1, and 1
Sample No. 3 was prepared by injection molding. The three-point bending strength, relative density, and return loss of each sample were measured. In addition, the orientation of the filler is determined by analyzing the photograph of the reflected electron image at two arbitrary cross-sections of the resin composite or tracing the photograph and measuring the angle of the long side direction of the permalloy on the photograph screen, respectively. Is calculated, and if all the angles of the long axis of the filler are within the range of 0 ° or more and less than 180 °, the probability that the filler is present within the range of 0 ° or more and less than 45 ° is 20%. ~ 30%, and 90 degrees or more 135
When the filler was present in a range of less than 20% with a probability of 20% to 30%, the result was evaluated as ○, and other cases were evaluated as ×. Also,
For the molded body whose orientation has been confirmed, the direction in which the load is applied is measured in each of the parallel direction and the perpendicular direction with respect to the direction in which the filler is oriented. X. The content of 0.1D to 10D was determined from image analysis of an arbitrary cross section of the resin composite material and the area occupancy. Further, as for the dimensional accuracy, the dimensions of the obtained molded body were measured, and those within ± 0.5% were evaluated as ○, and those other than this were evaluated as ×.

According to Table 2 and FIG. 3, in the case where permalloy was filled into a synthetic resin by injection molding (No. 13),
The orientation of the filler is remarkable, anisotropy of mechanical strength and anisotropy of dimensional accuracy occur, and the volume resistivity value is 10 ⁵ Ω ·
cm, the eddy current loss was large, and the return loss was small. Further, if the average particle size of permalloy is larger than 300 μm (No. 15), the maximum particle size exceeds 500 μm, and the aspect ratio is larger than 10 (No. 16), permalloy cannot be uniformly dispersed. In addition, the moldability was poor, and a resin composite could not be produced.

The occupancy of 0.1D to 10D is 40%.
A lower sample (No. 16) had poor moldability and was not practical.

On the other hand, the permalloy having an aspect ratio, an average particle size and a maximum particle size within the range of the present invention (N
o. 17-No. 19) In all the resin composites, the return loss from 0.1 to 10 GHz was measured by the S-parameter method. At this time, the thickness of the sample used for the measurement was 1 mm. As a result, the return loss is 20d.
Greater than B and good step accuracy within ± 0.5%
In addition, a strength of 50 MPa or more could be obtained, and a resin composite excellent as a radio wave absorber could be obtained.

[0065]

[Table 2]

Example 3 Next, a phenol resin (specific gravity: 1.1 g / cm ³ ) and carbon fiber (specific gravity: 1.2 g / cm ³ ) as a carbon material filler were used.
At a normal temperature at a molding pressure of 0,5% by volume.
After molding at 5-8 ton / cm ² and release, 80-250 ° C
The resin composites were cured by heating to prepare resin composites having different relative densities and relative density distributions, and the mechanical strength was measured. Also, N
o. 21-No. As shown in FIG. 2, when the lower punch 5 was fixed, the relative density of the obtained compact was lowered from the upper surface to the lower surface by lowering the upper punch 6 to a predetermined position and raising the die 7 as shown in FIG. Continuously lower. In addition, No. 20 samples can be obtained by operating the upper punch 6 and the lower punch 5 simultaneously.

The obtained sample was measured for relative density, three-point bending strength and deflection temperature under load in the same manner as in Example 1. The respective results are shown in Table 3 and FIG.

According to Table 3, the samples of the present invention (No. 23 to No. 25) in which the relative density of the main surface is larger than 70% as compared with the relative density inside the resin composite have a deflection temperature under load of 150%. It was excellent in heat resistance at a temperature of not less than ℃, and a strength of 50 MPa or more could be obtained.

[0069]

[Table 3]

Example 4 Resin composites were prepared in which the amount of the magnetic material and the relative density of the composite material were different from each other, and an experiment was conducted to examine the absorption characteristics with respect to radio waves of 0.1 to 100 GHz.

As a synthetic resin, a resol type phenol resin (specific gravity 1.1 g / cm ³ ), a permalloy (specific gravity 7.9 g / cm ³ ) for a magnetic material, and a shirasu balloon (specific gravity 1.1 g / cm ³ ) for an inorganic filler. ³ ) Pitch-based carbon fiber (specific gravity 1.2 g / cm ³ ) was used as the carbon filler. These were blended, press-molded at a normal temperature at a molding pressure of 0.5 to 8 ton / cm ² , released, and then heat-cured at 80 to 250 ° C. to produce a test piece. The thickness of the test piece was 1 mm. Next, with respect to the obtained test piece, the return loss, the three-point bending strength, and the relative density of the test piece at 0.1 to 100 GHz were measured.

The radio wave absorption from 0.1 to 10 GHz was measured by the S-parameter method, and the measurement from 10 to 100 GHz was measured by the arch method.

Table 4 shows the results.

According to Table 4, the permalloy content was less than 25% by volume (No. 26), permalloy, shirasu balloon,
When the carbon fiber content was less than 25% by volume (No. 30), the molded article could not be retained after heat treatment, and was not practical.

When the permalloy content exceeds 95% by volume (No. 27) or when the filling rate of permalloy, shirasu balloon and carbon fiber exceeds 95% by volume (N
o. 31) The return loss was reduced and was not practical.

When the relative density of the resin composite was less than 70% (No. 28 and No. 32), the amount of return loss and the strength were lowered, which was not practical.

On the other hand, the filling rate of permalloy, shirasu balloon, and carbon fiber was in the range of 30% by volume to 70% by volume, and the relative density was in the range of 70% or more (Nos. 33 to 3).
In 8), in all the resin composites, a return loss of 20 dB or more and a strength of 50 MPa or more could be obtained.

[0078]

[Table 4]

Example 5 Next, resin composites having different shapes, orientations, aspect ratios, average particle diameters D, the content of particles of 0.1 to 10 D, and maximum particle diameters of Permalloy were determined. Nos. 39 to 45 were produced in the same manner as in Example 4. The sample No. 38 was prepared by casting using a scaly permalloy. For each sample, the return loss of 0.1 to 100 GHz, the three-point bending strength, and the relative density were measured. The orientation of the filler, the content of 0.1D to 10D,
It was measured and determined as in Example 2.

According to Table 5, the resin having flaky permalloy (No. 38) had an aspect ratio of 10%.
Since the size was larger and the filler was oriented, anisotropy occurred in the strength. Further, the average particle size of permalloy is 300
If the particle size was larger than μm (Nos. 39 and 40) and the maximum particle size was larger than 500 μm, permalloy could not be uniformly dispersed, and the strength was reduced, which was not practical. Also,
Those having an area occupancy of 0.1D to 10D lower than 40% (No. 41) were not practical because of poor moldability.

On the other hand, the aspect ratio of Permalloy
Average particle size and maximum particle size within the range of the present invention (No. 4)
In Nos. 2 to 45), a return loss of 20 dB or more and a strength of 50 MPa or more were obtained in all the resin composites.

[0082]

[Table 5]

[0083]

According to the present invention, at least one of a magnetic material, an inorganic material, and a carbon-based material is added to a synthetic resin by 25%.
By maintaining the mechanical strength by making the composite material dispersed and containing up to 95% by volume and making the relative density 70% or more, desired excellent properties can be obtained by the blended filler, and the relative density can be controlled. Thus, a resin composite that can be reduced in size and weight can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a resin composite of the present invention.

FIG. 2 is a diagram illustrating a method for controlling the distribution state of relative density in the resin composite of the present invention by cold powder pressing.

FIG. 3 is a diagram in which a surface and a cross section of the resin composite are photographed with a backscattered electron image and traced.

FIG. 4 is a graph showing a relationship between a distance from a main surface of a resin composite and a relative density.

[Explanation of symbols]

 1: Main surface 2: Inside 4: Raw material powder 5: Lower punch 6: Upper punch 7: Die 8: Molded body 10: Resin composite

Continued on the front page F-term (reference) 4J002 AA001 AC031 BB031 BB061 BB071 BB121 BB171 BB221 BB231 BB241 BC031 BC061 BD041 BD121 BE031 BG061 BN151 CB001 CC031 CC161 CC181 CD001 CF061 CF161 CF211 CG001 CH071 DE0903 CN031 DE136 DE146 DE236 DE246 DE266 DE286 DG046 DG056 DJ006 DJ016 DJ036 DJ046 DJ056 DK006 DL006 FA016 FA017 FA046 FA047 FA067 FA086 FA106 FD016 FD017

Claims (9)

[Claims] 1. A synthetic resin containing 25 to 95% by volume of at least one filler selected from a magnetic material, an inorganic material, and a carbon-based material.
A resin composite comprising a composite material dispersed and contained, wherein the relative density of the composite material is 70% or more of the theoretical density. 2. The resin composite according to claim 1, wherein said magnetic material, inorganic material and carbon-based material are non-oriented. 3. The method according to claim 1, wherein the filler has an average aspect ratio of 1 or more and 1 or more.
The resin composite according to claim 2, wherein the average particle size is 0 or less, the average particle size is 1 μm or more and 300 μm or less, and the maximum particle size is 500 μm or less. 4. The resin composite according to claim 1, wherein 40% by volume or more of the filler is in the range of 0.1D to 10D, where D is the average particle size of the filler. body. 5. A radio wave absorber comprising the resin composite according to claim 1. 6. The radio wave absorber according to claim 5, wherein the relative density of said resin composite material varies depending on the portion. 7. The radio wave absorber according to claim 6, wherein the relative density of the main surface is higher than the relative density of the inside. 8. A method according to claim 5, wherein said resin composite material contains a magnetic material composed of an iron group metal containing at least one of a soft magnetic metal material and ferrite or a compound thereof. Radio wave absorber. 9. A composite material in which at least one or more fillers of a magnetic powder, an inorganic material, and a carbon material are dispersed and contained in a synthetic resin is molded by a powder press molding method, and after releasing, heat treatment is performed at a predetermined temperature. The method for producing a resin composite according to any one of claims 1 to 4, wherein