HK1098629A - Extrudable crosslinked greasy electromagnetic-wave absorber - Google Patents

Description

Extrudable crosslinked grease-like electromagnetic wave absorbing material

Technical Field

The present invention relates to an extrudable crosslinked grease-like electromagnetic wave absorbing material, a container filled and sealed with the material, a method for producing the container, and an electromagnetic wave absorbing method using the same. In particular, the present invention relates to an extrudable crosslinked grease-like electromagnetic wave absorbing material which is excellent in electromagnetic wave absorption, thermal conductivity and flame retardancy, has a small temperature dependency, and can be applied to gaps and thin layers in the case where application of a sheet product is difficult or the operation of laminating sheets is significantly disadvantageous, a container in which the material is filled and sealed, a method for producing the container, and an electromagnetic wave absorbing method using the same.

Background

With the recent development of electromagnetic wave applications such as broadcasting, mobile communication, radar, mobile phone, wireless LAN, and the like, electromagnetic waves are scattered in a living space, and problems such as electromagnetic wave failure and erroneous operation of electronic equipment occur at a high frequency. In particular, unnecessary electromagnetic waves (noise) radiated from internal elements of an apparatus or a printed circuit board pattern generating electromagnetic waves cause interference or resonance phenomena, resulting in deterioration of the performance and reliability of the apparatus, and measures against such electromagnetic waves of an adjacent electromagnetic field and measures against heat generation increase due to increase in speed of an arithmetic element are urgently required.

As a method for solving these problems, a reflection method of reflecting the generated noise to be restored to the generation source, a bypass method of guiding the noise to a potential stabilizing surface (a ground portion or the like), a shielding method, or the like are mainly adopted.

Recently, however, the mounting density has been increased due to the demand for smaller and lighter devices, and accordingly, the space for mounting noise coping parts has become smaller; since the low voltage of the element drive is required to save electric energy, it follows that the high frequency electromagnetic wave from other media is easily received in the power supply system; according to the requirement of rapidly increasing the operation processing speed, the synchronous pulse signal becomes narrow, and is easily influenced by high-frequency electromagnetic waves; with the rapid popularization of resin shells, a structure which is easy to leak electromagnetic waves is formed; for these reasons, all methods cannot be a method that satisfies both the requirements for the electromagnetic wave of the proximity electromagnetic field and the heat radiation at the same time, and this is the present situation.

In order to solve these problems, electromagnetic wave absorbers have been used which convert noise generated from elements and printed circuit board patterns in a resin case into thermal energy. The electromagnetic wave absorber is required to have a function of absorbing electromagnetic wave energy of generated noise by utilizing magnetic loss characteristics, converting the electromagnetic wave energy into thermal energy, and suppressing reflection and transmission of noise in the case, and a function of degrading an antenna effect by adding impedance to electromagnetic energy emitted as an antenna to the substrate pattern or the element terminal, and lowering an electromagnetic energy level.

As a method for dealing with these problems, a flexible thin electromagnetic wave absorber has been proposed in which a flexible sheet-like electromagnetic wave absorbing layer formed by mixing an electromagnetic wave energy loss material and a holding material and an electromagnetic wave reflecting layer formed by forming a highly conductive metal material on an organic fiber cloth by electroless plating are laminated (patent document 1).

In addition, in order to prevent electromagnetic waves from leaking to the outside of the device, a method of providing a metal plate as an electromagnetic wave shielding material or a method of providing electromagnetic wave shielding performance by providing a case with conductivity is adopted, but since such a shielding material causes reflected and scattered electromagnetic waves to fill the inside of the device, there are problems of promoting electromagnetic interference and electromagnetic interference between a plurality of substrates provided inside the device. In order to solve these problems, an electromagnetic interference suppressor in the form of an insulating soft magnetic layer containing a conductive support, soft magnetic powder, and an organic binder has been proposed (patent document 2).

An electromagnetic wave absorber characterized by laminating an electromagnetic wave absorbing layer in which an electromagnetic wave absorbing filler is dispersed in a silicone resin on at least one surface of an electromagnetic wave reflecting layer in which a conductive filler is dispersed in a silicone resin is also disclosed (patent document 3), which has high electromagnetic wave absorbing performance and high electromagnetic wave shielding performance, can exhibit the properties of the silicone resin itself, and is excellent in processability, flexibility, weather resistance, and heat resistance. Further, there is disclosed an electromagnetic wave absorbing and heat conducting silicone gel-molded sheet formed from a silicone gel composition containing metal oxide magnetic particles such as ferrite and a heat conducting filler such as metal oxide (patent document 4).

However, in any of the techniques, since the electromagnetic wave absorber is formed into a sheet shape, it is necessary to perform a complicated process such as cutting in order to cope with an opening (for example, a slit) for improving heat radiation efficiency provided in a case, which is difficult to apply a sheet product, and thus the requirements cannot be sufficiently satisfied. As a material used for coating or the like on such a portion, for example, an electromagnetic shielding insulating paste containing 200 to 900 parts by weight of soft magnetic powder per 100 parts by weight of an insulating resin and having a high magnetic permeability is disclosed (patent document 5); an electromagnetic wave absorbing binder containing a viscous body obtained by mixing an organic binder and a soft magnetic powder of sendust containing a coupling agent (patent document 6); a composite magnetic paste containing a composition of flat Fe — Al — Si alloy powder and an organic binder in a freely formable shape (patent document 7); a liquid radio interference preventing composition in which carbon fibers, magnetic particles, or graphitized carbon is blended with a silicone resin or the like (patent document 8); an electromagnetic wave shielding material in which magnetic powder is mixed with a thermosetting resin or the like which is liquid at the time of coating (patent document 9); an electromagnetic wave absorbing paste is formed by kneading an electromagnetic wave absorbing material containing magnetic particles and an organic binder (patent document 10). However, any of these materials is likely to cause a dripping phenomenon, a phenomenon of bleeding to the surroundings, and a phenomenon of separation from the magnetic powder, and thus cannot be applied to a target site with a sufficiently small thickness.

Patent document 1: japanese patent application laid-open No. 3097343

Patent document 2: japanese unexamined patent publication Hei 7-212079

Patent document 3: japanese laid-open patent publication No. 2002-329995

Patent document 4: japanese unexamined patent publication No. 11-335472

Patent document 5: japanese unexamined patent publication No. Hei 4-252498

Patent document 6: japanese unexamined patent publication No. 11-50029

Patent document 7: japanese unexamined patent publication No. 11-54985

Patent document 8: japanese laid-open patent publication No. 2000-244173

Patent document 9: japanese unexamined patent publication No. 2001-284877

Patent document 10: japanese laid-open patent publication No. 2001-77585

Disclosure of Invention

In view of the above-mentioned problems, it is an object of the present invention to provide an extrudable crosslinked grease-like electromagnetic wave absorbing material, a container filled and sealed with the material, a method for producing the container, and an electromagnetic wave absorbing method using the same. The extrudable crosslinked grease-like electromagnetic wave absorbing material is characterized in that: the composition can be put into a container such as a tube or a syringe as in the case of a grease, paste, clay, etc., can be squeezed out with a weak force to such an extent that the tube is gripped by a hand or the syringe piston is pushed by the force of air, can be formed into an arbitrary shape after the squeezing, does not cause a diffusion phenomenon (bleeding phenomenon) in a machine to which the composition is applied, has self-shape retaining properties capable of retaining its original shape even if it is held in a state of being slightly loaded as in an inclined state, has a small change with time as long as it is left as it is, is excellent in electromagnetic wave absorbability, thermal conductivity, flame retardancy, and small in temperature dependency, and can be suitably used for gaps and thin coating to which sheet products are difficult to apply.

In order to solve the above problems, the present inventors have made extensive studies and have considered that a filler for electromagnetic wave absorption is dispersed in a raw material for producing a silicone gel, and a crosslinked grease-like material which can be extruded after heating is obtained. However, the present inventors have unexpectedly found that a crosslinked grease-like electromagnetic wave absorbing material which is flowable and processable into a specific shape by a weak force of about a syringe piston or the like, and which has self-shape retention properties of retaining its original shape even when it is held in a state of being slightly loaded as in a tilted state, and which is excellent in electromagnetic wave absorbability, thermal conductivity and flame retardancy and has a small temperature dependency and is applicable to a gap of a sheet product and a thin coating and can be extruded, can be obtained by using soft ferrite and/or flat soft magnetic metal powder as an electromagnetic wave absorber and further preferably by blending a specific amount of a composite filler containing magnetite as a flame retardant.

That is, according to the invention of claim 1, there is provided an extrudable crosslinked grease-like electromagnetic wave absorbing material in which an electromagnetic wave absorbing filler is dispersed in a crosslinked silicone gel, the crosslinked grease-like electromagnetic wave absorbing material being characterized in that: the fluid, self-retaining property, and electromagnetic wave absorbing filler content is 200-800 parts by weight per 100 parts by weight of the crosslinked silicone gel.

The invention according to claim 2 provides the extrudable crosslinked grease-like electromagnetic wave absorbing material according to claim 1, wherein the crosslinked silicone gel has a consistency of 50 to 200(JISK 22201/4 Cone).

The invention according to claim 3 provides the extrudable crosslinked grease-like electromagnetic wave absorbing material according to claim 1 or 2, wherein the filler for electromagnetic wave absorption is a mixture of an electromagnetic wave absorber and a flame retardant.

The invention according to claim 4 provides the extrudable crosslinked grease-like electromagnetic wave absorbing material according to claim 3, wherein the electromagnetic wave absorber is a soft ferrite and/or a flat soft magnetic metal powder surface-treated with a non-functional group silane compound.

The invention according to claim 5 provides the extrudable crosslinked grease-like electromagnetic wave absorbing material according to claim 4, wherein the soft ferrite surface-treated with the non-functional group silane compound is a soft ferrite surface-treated with dimethyldimethoxysilane or methyltrimethoxysilane.

The invention according to claim 6 provides the extrudable crosslinked grease-like electromagnetic wave absorbing material according to claim 4 or 5, wherein the soft ferrite surface-treated with the non-functional group-based silane compound has a pH of 8.5 or less.

The invention according to claim 7 provides the extrudable crosslinked grease-like electromagnetic wave absorbing material according to any one of claims 3 to 6, wherein the flame retardant is magnetite.

The 8 th aspect of the present invention provides a container filled and sealed with the extrudable crosslinked grease-like electromagnetic wave absorbing material according to any one of the 1 st to 7 th aspects of the present invention.

The invention according to claim 9 provides the container according to claim 8, wherein the container is in the form of a syringe or a tube.

The present invention according to claim 10 provides the method for manufacturing a container according to claim 8 or 9, wherein: when the electromagnetic wave absorbing filler is dispersed in the crosslinked silicone gel, the raw material substance of the crosslinked silicone gel and the electromagnetic wave absorbing filler are mixed together or are mixed together, and then heated to obtain a crosslinked grease-like electromagnetic wave absorbing material, and then the crosslinked grease-like electromagnetic wave absorbing material is filled and sealed in a container.

According to the 11 th aspect of the present invention, there is provided the method for manufacturing a container according to the 8 th or 9 th aspect, wherein: when the electromagnetic wave absorbing filler is dispersed in the crosslinked silicone gel, a mixed solution obtained by mixing the raw material of the crosslinked silicone gel and the electromagnetic wave absorbing filler is filled and sealed in a container, and then the entire container is heated to crosslink the silicone gel in the container.

According to the invention of claim 12, there is provided a method for absorbing unnecessary electromagnetic waves, comprising: a crosslinked grease-like electromagnetic wave absorbing material filled and sealed in the container of the invention of claim 8 or 9 is applied in the form of a film to the periphery of the heat-radiating opening in the case to suppress the radiation of unnecessary electromagnetic waves from the heat-radiating opening.

The extrudable crosslinked grease-like electromagnetic wave absorbing material of the present invention is excellent in electromagnetic wave absorption, thermal conductivity and flame retardancy, has a small temperature dependence, and is suitable for gaps and thin coatings where sheet products are difficult to apply. The crosslinked grease-like heat-releasing material which can be extruded in the present invention can be put into a container such as a tube or a syringe like grease, paste, clay, etc., and can be extruded with a weak force such as to hold the tube with a hand or push the syringe piston with the force of air, and can be formed into any shape by applying a force after extrusion.

Drawings

FIG. 1 is a graph showing the results of measurement of the magnetic loss of the electromagnetic wave absorbing material of the example.

Detailed Description

The present invention relates to an electromagnetic wave absorber containing (a) soft ferrite, (c) magnetite and (d) silicone; an electromagnetic wave absorber containing (a) a soft ferrite, (b) a flat soft magnetic metal powder, (c) a magnetite and (d) a silicone gel; the electromagnetic wave absorber includes an electromagnetic wave absorbing layer containing the electromagnetic wave absorber and an electromagnetic wave reflecting layer containing a conductor, and is a laminated electromagnetic wave absorber in which a release film layer, an electromagnetic wave absorbing layer, an electromagnetic wave reflecting layer, an insulator layer, an adhesive layer, and a release film layer are laminated in this order. The respective constituent components, production methods, and the like will be described in detail below.

The extrudable crosslinked grease-like electromagnetic wave absorbing material of the present invention is a material in which an electromagnetic wave absorbing filler is dispersed in a crosslinked silicone gel, the container of the present invention is a container filled and sealed with the extrudable crosslinked grease-like electromagnetic wave absorbing material, and the container manufacturing method of the present invention is a method for filling and sealing the extrudable crosslinked grease-like electromagnetic wave absorbing material. The components, the container and the production method will be described in detail below.

1. Cross-linked silicone gels

In the grease-like electromagnetic wave absorbing material that can be extruded in the present invention, a cross-linked silicone gel is used as a matrix of the grease-like electromagnetic wave absorbing material. Although the crosslinked silicone gel itself is a known chemical substance, a specific crosslinked silicone gel satisfying the following conditions is particularly preferable as a substance used for the grease-like electromagnetic wave absorbing material that can be extruded in the present invention: has a fluidity to such an extent that it can be extruded from a syringe or a tube or the like; even if a large amount of the electromagnetic wave absorbing filler is blended, the thermoplastic elastomer composition has plasticity and self-shape retention; does not contain a low molecular weight silicone compound; a small amount of residual alkenyl groups; a small residual amount of hydrogen radicals directly bonded to silicon, and the like.

The consistency of the crosslinked silicone gel measured by JIS K22201/4 Cone is 50-200. When the consistency exceeds 200, the self-retaining property is lost, and bleeding and diffusion to the surroundings occur during application; if the consistency is less than 50, the fluidity is deteriorated, so that it is not preferable.

The method for producing the crosslinked silicone gel used in the present invention is not particularly limited. Usually, the organopolysiloxane is obtained by using an organohydrogenpolysiloxane and an alkenylpolysiloxane, which will be described later, as raw materials, and subjecting them to a hydrosilylation reaction (addition reaction) in the presence of a catalyst. That is, the raw material of the silicone gel in the present invention is usually an organohydrogenpolysiloxane and an alkenylpolysiloxane. The organohydrogenpolysiloxane used as one of the raw materials is preferably represented by the following general formula (1).

[ chemical formula 1]

In the general formula (1), R¹Represent identical or different, substituted or unsubstituted, 1-valent hydrocarbon radicals, R²、R³And R⁴Represents R¹or-H, R²、R³And R⁴At least 2 of them represent-H, x and y are integers representing the number of the respective units, the respective units are arranged in blocks or randomly, preferably randomly, x is an integer of 0 or more, preferably 10 to 30, and y is an integer of 0 or more, preferably 1 to 10. x + y is an integer of 5 to 300, preferably 30 to 200. Further, it is preferable that y/(x + y) ≦ 0.1, and if it exceeds this range, the number of crosslinking points increases, and the crosslinked grease-like material of the present invention cannot be obtained. As R¹Examples of the (C) include alkyl groups such as methyl, ethyl, propyl and butyl, cycloalkyl groups such as cyclopentyl and cyclohexyl, aromatic groups such as phenyl and tolyl, aromatic hydrocarbon groups such as benzyl and phenylethyl, and halogenated hydrocarbons in which a part of hydrogen atoms are substituted with chlorine atoms, fluorine atoms and the like.

In order to perform an addition reaction (hydrosilylation reaction) with an alkenyl group directly or indirectly bonded to a silicon atom, hydrogen (Si — H) directly bonded to a silicon atom is necessary, at least 2 hydrogen atoms are necessary in the molecule of the organohydrogenpolysiloxane, and if the number of hydrogen atoms directly bonded to a silicon atom is small, the number of crosslinking points is too small to form a silicone gel, and is not preferable since it is not different from the property of silicone oil; if the amount of hydrogen directly bonded to the silicon atom is too large, the number of crosslinking points is too large, which is not different from the properties of the silicone rubber, and thus is not preferable. Of course, the number of Si-H groups in the organohydrogenpolysiloxane and the number of alkenyl groups in the alkenylpolysiloxane are in a relatively preferred ratio, and in the present invention, the Si-H groups/alkenyl groups are preferably contained in an amount of 0.85 to 1.25, and particularly preferably in a range of 0.9 to 1.1. When the content is within this range, the number of alkenyl groups remaining is reduced, so that the oxidation degradation in an electronic device exposed to high temperatures is reduced, the number of remaining Si-H groups is also reduced, and the reduction in thermal conductivity due to the generation of hydrogen is also reduced.

The alkenyl polysiloxane used as another raw material for producing the crosslinked silicone gel of the present invention is preferably represented by the following general formula (2).

[ chemical formula 2]

In the general formula (2), R¹Represent identical or different, substituted or unsubstituted, 1-valent hydrocarbon radicals, R⁵、R⁶And R⁷Represents R¹Or alkenyl, R⁵、R⁶And R⁷At least 2 of which represent alkenyl groups, s and t are integers representing the number of the respective units, the respective units being in block or random arrangement, preferably random arrangement, s represents an integer of 0 or more, t represents an integer of 0 or more, s + t is an integer of from 10 to 600, and preferably t/(s + t) ≦ 0.1, and if this is exceeded, the number of crosslinking sites increases and no crosslinked grease-like material of the invention is obtained. As R¹Examples of the (C) include alkyl groups such as methyl, ethyl, propyl and butyl, cycloalkyl groups such as cyclopentyl and cyclohexyl, aromatic groups such as phenyl and tolyl, aromatic hydrocarbon groups such as benzyl and phenylethyl, and halogenated hydrocarbons in which a part of hydrogen atoms are substituted with chlorine atoms, fluorine atoms and the like.

In order to carry out an addition reaction (hydrosilylation reaction) with hydrogen (Si — H) directly bonded to a silicon atom, alkenyl groups (vinyl groups, allyl groups, and the like) directly or indirectly bonded to a silicon atom are necessary, at least 2 alkenyl groups are necessary in the molecule of the alkenyl polysiloxane, and if the number of alkenyl groups is small, the number of crosslinking points is too small to form a silicone gel, and is not preferable because it is not different from the properties of silicone oil; if the number of alkenyl groups is too large, the number of crosslinking points is too large, which is not different from the properties of silicone rubber, and thus it is not preferable. Of course, the number of alkenyl groups in the alkenyl polysiloxane and the number of hydrogen atoms (Si-H) directly bonded to silicon atoms in the organohydrogenpolysiloxane are in a relatively preferable ratio, and in the present invention, the content is preferably in an amount such that the Si-H group/alkenyl group ratio is 0.85 to 1.25, and particularly preferably in a range of 0.9 to 1.1, for the same reason as described above. The number of s + t determines the distance between the crosslinking points, and if the number is small, the number of crosslinking points increases, which is not preferable; if the number of s + t is too large, the number of crosslinking points decreases, which is not preferable; the molecular weight also becomes too large to be extruded from a syringe, and is therefore not preferred.

In the present invention, the hydrogenpolysiloxane represented by the general formula (1) has-H (hydrogen group) directly bonded to a silicon atom, and the alkenylpolysiloxane represented by the general formula (2) has a carbon-carbon double bond, so that an addition reaction of the carbon-carbon double bond and-H (hydrogen group) occurs, and this reaction is referred to as a hydrosilylation reaction.

The hydrosilylation reaction can be carried out by a known technique. That is, the reaction is carried out in an alcohol-based organic solvent such as ethanol or isopropanol, an aromatic hydrocarbon-based organic solvent such as toluene or xylene, an ether-based organic solvent such as dioxane or THF, an aliphatic hydrocarbon-based organic solvent or a chlorinated hydrocarbon-based organic solvent, or under a solvent-free condition. The reaction temperature is usually 50 to 150 ℃ and the reaction can be carried out using a catalyst such as chloroplatinic acid, a complex obtained from chloroplatinic acid and an alcohol, a platinum-olefin complex, a platinum-vinylsiloxane complex, or a platinum-phosphorus complex. The amount of the catalyst used is usually 1 to 500ppm as a platinum atom to the alkenyl polysiloxane, and preferably 3 to 250ppm in view of curability and physical properties of the cured product.

2. Filler for absorbing electromagnetic wave

The filler for electromagnetic wave absorption that can be incorporated in the crosslinked silicone gel of the present invention is not particularly limited as long as it is an electromagnetic wave absorber having an electromagnetic wave absorbing function. Examples thereof include soft ferrite and flat soft magnetic metal powder. These may be used in 1 kind or in a mixture of several kinds, and composite fillers containing these electromagnetic wave absorbers and a flame retardant are further preferred.

The soft ferrite as the electromagnetic wave absorber which can be incorporated into the crosslinked silicone gel of the present invention is a substance which can exhibit a magnetic function even under a weak excitation current. The soft ferrite is not particularly limited, and examples thereof include Ni-Zn ferrite, Mn-Mg ferrite, Cu-Zn ferrite, Ni-Zn-Cu ferrite, Fe-Mg-Zn-Cu ferrite, Fe-Mn-Zn ferrite and the like, and among these soft ferrites, Ni-Zn ferrite is preferable in terms of the balance of electromagnetic wave absorption characteristics, thermal conductivity, price and the like.

The shape of the soft ferrite is not particularly limited, and may be a desired shape such as a sphere, a fiber, or an amorphous shape. In the present invention, in order to enable filling with a high filling density and to obtain higher thermal conductivity, the soft ferrite is preferably spherical in shape. When the soft ferrite has a spherical shape, the particle size can be filled at a high filling density, and the aggregation of particles can be prevented, thereby facilitating the compounding operation.

By using Ni — Zn ferrite in such a shape, the dispersibility in a silicone gel material is excellent without causing the later-described inhibition of curing of the silicone gel, and the thermal conductivity can be exhibited to some extent.

Particle size distribution D of Soft ferrites₅₀1 to 30 μm, preferably 1 to 10 μm. If the particle size distribution D of the soft ferrite₅₀When the particle size is less than 1 μm, the electromagnetic wave absorption energy tends to be lowered in a low frequency band of 500MHz or less; if it exceeds 30 μm, the smoothness of the electromagnetic wave absorber is poorAnd is not preferred.

Here, the particle diameter distribution D₅₀The particle size ranges from a value obtained by a particle size distribution analyzer, in which the particle size is small, to a value obtained when the cumulative weight of particles reaches 50%.

In order to suppress the influence of the residual alkali ions present on the surface of the soft ferrite, the soft ferrite used in the present invention must be treated with a non-functional group-based silane compound. The soft ferrite is used in combination with silicone described later, but the residual alkali ions present on the surface of the soft ferrite sometimes become a factor of curing inhibition in the condensation type or addition curing mechanism of silicone, and if curing inhibition occurs, the soft ferrite cannot be highly filled, and the filled soft ferrite is not sufficiently dispersed.

The pH of the soft ferrite surface-treated with the nonfunctional silane compound is 8.5 or less, preferably 8.2 or less, more preferably 7.8 to 8.2 by treating the surface of the soft ferrite with the nonfunctional silane compound. By setting the pH of the soft ferrite to 8.5 or less, inhibition of curing of silicone can be suppressed, and the soft ferrite can be applied to any silicone, and the affinity between the soft ferrite and silicone is good, so that the filling amount of the soft ferrite in silicone can be increased, and the miscibility with the thermally conductive filler can be improved, and a uniform molded body can be obtained.

Examples of the nonfunctional silane compound for the surface treatment of soft ferrites which can be used in the present invention include methyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane and decyltrimethoxysilane. Among them, dimethyldimethoxysilane and methyltrimethoxysilane are preferable. These non-functional silane compounds may be used alone or in combination of two or more.

When a silane coupling agent having a functional group, such as an epoxy silane compound or a vinyl silane compound, which is generally used for surface treatment of fillers or the like, is used as the silane compound for surface treatment of the soft ferrite of the present invention, if a hardness change, i.e., a rise in hardness, occurs in an environmental test under heating, cracks or the like due to thermal decomposition occur, and the shape cannot be maintained, resulting in appearance deterioration, which is not preferable.

The surface treatment method of the soft ferrite by the above-mentioned non-functional group silane compound is not particularly limited, and an inorganic compound surface treatment method by a general silane compound or the like can be employed. For example, the soft ferrite is obtained by immersing and mixing the soft ferrite in a methanol solution of about 5% by weight of dimethyldimethoxysilane, adding water to the solution, hydrolyzing the mixture, and pulverizing and mixing the resulting treated product with a Henschel mixer or the like. The amount of the non-functional group silane compound is preferably about 0.2 to 10 wt% based on the soft ferrite.

The flat soft magnetic metal powder as an electromagnetic wave absorber that can be incorporated in the crosslinked silicone gel of the present invention is a material having an effect of stabilizing the energy conversion efficiency in a wide frequency band of MHz to 10 GHz.

The flat soft magnetic metal powder is not particularly limited as long as it exhibits soft magnetism and can be flattened by mechanical treatment. It is preferable that the magnetic material has a high magnetic permeability, a low self-oxidizing property, and a high aspect ratio (a value obtained by dividing the average particle diameter by the average thickness) in terms of shape. Specific examples of the metal powder include soft magnetic metals such as Fe-Ni alloy system, Fe-Ni-Mo alloy system, Fe-Ni-Si-B alloy system, Fe-Si-Al alloy system, Fe-Si-B alloy system, Fe-Cr-Si alloy system, Co-Fe-Si-B alloy system, Al-Ni-Cr-Fe alloy system, and Si-Ni-Cr-Fe alloy system, and among them, Al or Si-Ni-Cr-Fe alloy system is particularly preferable from the viewpoint of low self-oxidation property. These alloys may be used in 1 kind, or 2 or more kinds may be mixed and used.

The autoxidability can be determined by measuring the rate of change in weight of a sample by performing an exposure test in a heated atmosphere. Preferably a substance having a weight change rate of 0.3% or less when exposed to an atmosphere of 200 ℃ for 300 hours. If the flat soft magnetic metal powder has low self-oxidizing properties, it is characterized in that even if a silicone gel or the like having high permeability is used as the binder resin, the deterioration of the magnetic properties with the passage of time due to the change in the ambient environmental conditions such as humidity does not occur. Therefore, there is an advantage that any adhesive resin can be used.

Further, if the autoxidability is low, there is no risk of dust explosion, and the product can be handled as a non-hazardous substance and stored in a large amount, and has advantages of easy use and improved production efficiency.

The average thickness of the flat soft magnetic metal powder is preferably 0.01 to 1 μm, and when it is thinner than 0.01 μm, the dispersibility in the resin is poor, and the particles cannot be aligned in one direction sufficiently even if orientation treatment with an external magnetic field is applied. Even if the materials have the same composition, magnetic properties such as magnetic permeability are reduced, and magnetic shielding properties are also reduced. In contrast, if the average thickness exceeds 1 μm, the filling ratio decreases. Further, since the aspect ratio is small, the influence of the diamagnetic field is increased, and the magnetic permeability is lowered, so that the shielding property is insufficient.

Further, the particle size distribution D of the flat soft magnetic metal powder₅₀Preferably 8 to 42 μm. If the particle size distribution D₅₀Below 8 μm, the energy conversion efficiency is reduced; if it exceeds 42 μm, the mechanical strength of the particles is lowered, and the particles are easily broken when mechanically mixed.

Here, the particle diameter distribution D₅₀The particle size ranges from a value at which the particle size obtained by a particle size distribution analyzer is small to a value at which the cumulative weight reaches 50%.

Further, the specific surface area of the flat soft magnetic metal powder is preferably 0.8 to 1.2m²(ii) in terms of/g. Since flat soft magnetic metal powder is a material that realizes an energy conversion function by electromagnetic induction, high energy conversion efficiency can be maintained as the specific surface area is larger, but the flat soft magnetic metal powder has a higher energy conversion efficiencyThe larger the specific surface area, the lower the mechanical strength. It is therefore necessary to select the optimum range. If the specific surface area is less than 0.8m²(iv)/g, then high fill can be done, but the energy exchange function is reduced; if it exceeds 1.2m²When the amount is/g, the powder is easily broken during mechanical mixing, and it is difficult to maintain the shape, and even if high filling is possible, the energy exchange function is reduced.

The specific surface area herein is a value measured by a BET measuring apparatus.

The aspect ratio is preferably 17 to 20, and the bulk density is preferably 0.55 to 0.75 g/ml. Further, it is preferable to subject the surfaces of these metallic magnetic flat powders to an antioxidant treatment.

The flat soft magnetic metal powder used in the present invention is preferably used after microencapsulation treatment. When flat soft magnetic metal powder and soft ferrite are compositely filled, the volume resistance and dielectric breakdown strength are likely to be reduced. The microencapsulation treatment can prevent the dielectric breakdown strength from being lowered and can improve the strength.

The method of microencapsulation is not particularly limited, and any method may be used as long as the method is a method of coating the surface of the flat soft magnetic metal powder with a constant thickness and treating the surface with a material that does not affect the energy conversion function of the flat soft magnetic metal powder.

For example, as a material for coating the surface of flat soft magnetic metal powder, gelatin can be used, and soft magnetic metal powder is dispersed in a toluene solution in which gelatin is dissolved, and toluene is evaporated and removed to obtain flat soft magnetic metal powder in which soft magnetic metal powder is coated with gelatin and microencapsulated. In this case, for example, a material having a particle size of about 100 μm can be obtained by microencapsulating a material in which the weight of gelatin is 20% and the weight of flat soft magnetic metal powder is about 80%, and the dielectric breakdown strength of the electromagnetic wave absorber using the material can be increased by about 2 times as high as that when microencapsulating is not performed.

As a resistor used in addition to the above electromagnetic wave absorberA combustion agent, preferably magnetite, which is iron oxide (Fe)₃O₄) By using the soft ferrite and/or the flat soft magnetic metal powder together, the electromagnetic wave absorbing material can be provided with flame retardancy, and at the same time, the thermal conductivity can be improved, and further, the electromagnetic wave absorbing effect of the electromagnetic wave absorbing material as a whole can be improved by the synergistic effect of the additional magnetic properties of the magnetite.

Particle size distribution D of magnetite₅₀Preferably 0.1 to 0.4 μm. By making the particle size distribution D of magnetite₅₀To achieve the soft ferrite grain diameter distribution D₅₀About 1/10, a highly filled soft ferrite can be obtained. In addition, if the particle size distribution D of magnetite is₅₀Below 0.1 μm, use is difficult; if it exceeds 0.4 μm, high filling with soft ferrite cannot be performed.

Here, the particle diameter distribution D₅₀The particle size ranges from a value at which the particle size obtained by a particle size distribution analyzer is small to a value at which the cumulative weight reaches 50%.

The shape of the magnetite is not particularly limited, and the magnetite may be formed into a desired shape such as a spherical shape, a fibrous shape, an amorphous shape, and the like. In the present invention, octahedral fine particles are preferable for obtaining high flame retardancy. When magnetite is fine particles in the shape of octahedron, the specific surface area is large, and the effect of imparting flame retardancy is good.

In the electromagnetic wave absorbing material of the present invention, when a composite agent of soft ferrite and magnetite, which is surface-treated with a nonfunctional silane compound, is used as a filler for electromagnetic wave absorption, the combination of 60 to 90 wt% of soft ferrite and 3 to 25 wt% of magnetite, which are surface-treated with a nonfunctional silane compound, is preferable, and the electromagnetic wave absorbing material can be preferably used for applications of high resistance and high insulation.

When a composite agent containing flat soft magnetic metal powder and magnetite is used as the electromagnetic wave absorbing filler, a combination of 60 to 70 wt% of the flat soft magnetic metal powder and 3 to 10 wt% of the magnetite is preferable, and the filler can be preferably used for applications with high electromagnetic wave absorption characteristics in the 2 to 4GHz band.

Further, when a composite agent in which soft ferrite, flat soft magnetic metal powder and magnetite are combined is used as the electromagnetic wave absorbing filler, a combination of 40 to 60 wt% of soft ferrite surface-treated with a non-functional group-based silane compound, 20 to 30 wt% of flat soft magnetic metal powder and 3 to 10 wt% of magnetite is preferable, and the electromagnetic wave absorbing filler can be preferably used for applications with wide-range frequency characteristics of MHz to 10 GHz.

In the extrudable crosslinked grease-like electromagnetic wave absorbing material of the present invention, the amount of the filler for electromagnetic wave absorption is 200 to 800 parts by weight per 100 parts by weight of the crosslinked silicone gel. If the amount of the electromagnetic wave absorbing filler added is less than 200 parts by weight, the energy conversion efficiency is poor, which is not preferable; when the amount exceeds 800 parts by weight, the extrudable crosslinked grease-like electromagnetic wave absorbing material loses fluidity and cannot be extruded from a syringe or the like, which is not preferable.

3. Extrudable crosslinked grease-like electromagnetic wave absorbing material

The crosslinked grease-like electromagnetic wave absorbing material which can be extruded according to the present invention is a composite material in which a filler for electromagnetic wave absorption is dispersed in a matrix of a crosslinked silicone gel. Generally, if silicone is highly filled with an inorganic filler such as ferrite, flat soft magnetic metal powder, or magnetite, the viscosity increases, and roll kneading, banbury kneading, or kneading becomes difficult, and if kneading becomes possible, the viscosity of the mixture tends to increase, but kneading can be easily performed by treating the surface of the ferrite with a non-functional group-based silane compound. Further, in general, when high-filled ferrite is kneaded with silicone by a roll, the retention strength of silicone with respect to ferrite is insufficient, and the ferrite cannot be aggregated with each other, and the compound adheres to the roll, and a uniform compound cannot be formed. Further, when a substance obtained by microencapsulating flat soft magnetic metal powder is used, the effect of easier kneading is obtained.

In the case of using the grease-like crosslinked electromagnetic wave absorbing material of the present invention, the grease-like crosslinked electromagnetic wave absorbing material can be used by being extruded from a container such as a syringe filled and sealed with the extrudable grease-like crosslinked electromagnetic wave absorbing material, and then applied to a site where an essential material such as a sheet cannot be used, or poured into a space, or extruded into the inside of the container. The grease-like crosslinked electromagnetic wave absorbing material used in the present invention has a feature of being able to retain its original shape even when it is retained in a state of being slightly loaded, for example, in an inclined state after application, because it has self-conformability.

The term "crosslinked" in the present invention means a product based on a technical idea different from that of a conventionally used uncrosslinked silicone resin. The term "extrudable" means that the material can be used by extrusion from a container such as a syringe filled and sealed with the material, and any method of pouring, extruding, or applying the material to an extrusion coating object can be used even if the shape of the extrusion coating object is any shape.

4. Container with a lid

The extrudable crosslinked grease-like electromagnetic wave absorbing material of the present invention can be used by filling and sealing the material in a container in an extrudable state. The container is not particularly limited as long as it is a container which can store a fluid and has a function of injecting and/or discharging an arbitrary amount of fluid, such as a syringe, a tube, and the like, and which has a fluid storage portion, a fluid injection port, a fluid discharge port, a piston and a gear for injecting or discharging a fluid, a cap, a seal, and the like. For example, there are various types for pipes: a type having a fluid injection port and a fluid injection port; a type having only one port serving as both a fluid injection port and a fluid injection port; although initially having a fluid injection port and a fluid discharge port, after the fluid is injected, the fluid injection port is closed, leaving only the type of the fluid discharge port; although initially having a fluid injection port and a fluid injection port, the two ports are closed after the fluid is injected. Examples of the method of closing the fluid inlet or the fluid outlet include various methods selected from a plug, a cap with a rotary groove, heat sealing, and sealing.

The container may be provided with a heating device, a cooling device, a pressure reducing device, a pressurizing device, a suction device, an evaporation device, a motor, an oil pressure device, an air pressure device, a metering device, a dust-proof device, an operation auxiliary device, a display device, a generated gas discharge device, a backflow preventing device, a temperature detecting device, and the like. Most used are containers or tubes in the shape of e.g. syringes.

The method for filling and sealing the crosslinked silicone gel and the electromagnetic wave absorbing filler in the extrudable crosslinked grease-like electromagnetic wave absorbing material container of the present invention is not particularly limited, and examples thereof include the following 2 methods.

(1) In the case of dispersing the electromagnetic wave absorbing filler in the crosslinked silicone gel, the crosslinked grease-like electromagnetic wave absorbing material is obtained by heating the crosslinked silicone gel during or after mixing of the raw material substance and the electromagnetic wave absorbing filler, and then the crosslinked grease-like electromagnetic wave absorbing material is filled and sealed in a container. By this method, a large amount of the raw material of the crosslinked silicone gel and the electromagnetic wave absorbing filler can be mixed and heated in a large container, and thus the production can be carried out with high productivity. In addition, when filling and sealing a container such as a syringe or a tube, it is necessary to fill and seal the container while degassing the container in order to prevent air bubbles from being entrapped.

(2) When the electromagnetic wave absorbing filler is dispersed in the crosslinked silicone gel, a mixed solution obtained by mixing the raw material of the crosslinked silicone gel and the electromagnetic wave absorbing filler is filled and sealed in a container, and then the entire container is heated to crosslink the silicone gel in the container. By this method, since the mixture of the raw material of the crosslinked silicone gel and the filler for electromagnetic wave absorption can be filled and sealed in a container such as a syringe or a tube in a low-viscosity liquid state, mixing of air bubbles can be further prevented and the product can be provided and used in a higher quality state.

5. Electromagnetic wave absorption method

The crosslinked grease-like electromagnetic wave absorbing material which can be extruded in the present invention can be extruded from the outlet of a container in which the material is filled and sealed, and is applied in a thin film form around the opening (such as a slit) for heat radiation of a case in which an electronic device is incorporated, thereby suppressing the radiation of unnecessary electromagnetic waves from the opening for heat radiation. Examples of the device having the heat radiating opening include a Personal Computer (PC), a DVD drive, and a Television (TV).

Examples

The present invention will be described in more detail below by way of examples and comparative examples, but the present invention is not particularly limited to these examples. The physical property values in the examples were measured by the following methods.

(1) Method for testing diffusion phenomenon (bleeding phenomenon): a crosslinked grease-like electromagnetic wave absorbing material (50 g) was placed between 2 glass plates, and pressure was applied so that the interval between the two glass plates became 2mm and the thickness of the crosslinked grease-like electromagnetic wave absorbing material became 2mm, and then the two glass plates were set in a horizontal state and an inclined state without applying pressure. Then, the test was continuously carried out for 300 hours in an environmental tester at-4 ℃ for 30 minutes and at 100 ℃ for 30 minutes, and the state of the electromagnetic wave absorbing material was confirmed.

(2) Consistency: determined according to JIS K22201/4 Cone.

(3) Magnetic loss (magnetic permeability): the magnetic permeability and the inductivity were measured by using a magnetic permeability & inductivity measuring system (S parameter system coaxial tube, manufactured by Anritsu & Keycom Co., Ltd.; μ r measuring instrument system).

(4) Volume resistance: measured according to JIS K6249.

(5) Dielectric breakdown strength: measured according to JIS K6249.

(6) Coefficient of thermal conductivity: measured according to the QTM method (Kyoto electronics industries Co., Ltd.).

(7) Flame retardancy: measured according to UL 94.

(8) Heat resistance: the sample was left at a constant temperature of 150 ℃ to measure the penetration and the thermal conductivity, and the change with time was observed. The time of change can be observed.

Example 1

An addition reaction type silicone gel (SIG5000 (product name) manufactured by shin-Etsu chemical Co., Ltd.) capable of curing to a consistency (JIS K22201/4 Cone) of 130 was added to 12 wt%, and the resulting mixture was subjected to a particle size distribution D treatment with methyltrimethoxysilane₅₀A soft ferrite having a particle size distribution D of 83 wt% and surface-treated with Ni-Zn soft ferrite (BSN-714 (trade name) manufactured by Koita industries, Ltd.) of 1 to 10 μm₅₀5 wt% of octahedral magnetite fine particles (KN-320 (trade name): manufactured by Konta Industrial Co., Ltd.) having an inner volume of 30cm were uniformly dispersed in a reaction vessel in a vacuum defoamed state, and the mixture was charged in a vacuum defoamed state³The cross-sectional area of the injection port is 2mm²The syringe (3) is heated at 80 ℃ for 30 minutes to crosslink the entire syringe, thereby obtaining a syringe filled and sealed with the crosslinked grease-like electromagnetic wave absorbing material of the present invention. When the syringe piston is pushed lightly with a thumb, the crosslinked grease-like electromagnetic wave absorbing material can be extruded from the injection port. The crosslinked grease-like electromagnetic wave absorbing material was tested and evaluated in the above-described manner.

The substance placed in a horizontal state had its periphery held in the original position, and no diffusion phenomenon (bleeding phenomenon) was observed. Further, no dripping phenomenon was observed with the substance placed in the inclined state. And the crosslinked grease-like electromagnetic wave absorbing material shows very little change with time.

The evaluation results of the crosslinked grease-like electromagnetic wave absorbing material are shown in table 1. The magnetic loss was measured in the range of 0.5 to 10GHz, and the result is A shown in FIG. 1.

Example 2

An addition reaction type silicone gel (SIG5000 (product name) manufactured by shin-Etsu chemical Co., Ltd.) capable of curing to a consistency (JIS K22201/4 CONE) of 130 was added to 20% by weight, and the resultant was subjected to a particle size distribution D treatment with methyltrimethoxysilane₅₀50 wt% of Ni-Zn soft ferrite (BSN-714) (product name) made by Suitan industries, Ltd.) having a particle size distribution D of 1 to 10 μm₅₀25 wt% flat soft magnetic metal powder having a particle size distribution D of 8 to 42 μm and a self-oxidizing property of 0.26%₅₀5 wt% of octahedral magnetite fine particles (KN-320 (trade name): manufactured by Konta Industrial Co., Ltd.) having an inner volume of 30cm are uniformly dispersed in a reaction vessel in a vacuum defoamed state, and the mixture is charged in a vacuum defoamed state³The cross-sectional area of the injection port is 2mm²The syringe (3) is heated at 80 ℃ for 30 minutes to crosslink the entire syringe, thereby obtaining a syringe filled and sealed with the crosslinked grease-like electromagnetic wave absorbing material of the present invention. When the syringe piston is pushed lightly with a thumb, the crosslinked grease-like electromagnetic wave absorbing material can be extruded from the injection port. The crosslinked grease-like electromagnetic wave absorbing material was tested and evaluated in the above-described manner.

The substance placed in a horizontal state had its periphery held in the original position, and no diffusion phenomenon (bleeding phenomenon) was observed. No dripping phenomenon was observed with the material set in the inclined state. And the crosslinked grease-like electromagnetic wave absorbing material shows very little change with time.

The evaluation results of the crosslinked grease-like electromagnetic wave absorbing material are shown in table 1. The magnetic loss was measured in the range of 0.5 to 10GHz, and the result is B shown in FIG. 1.

Comparative example 1

The soft ferrite without surface treatment was added to the silicone gel used in example 1, and a curing test was performed. The evaluation results are shown in table 1. The amount of the soft ferrite added was 20% by weight, which caused the inhibition of curing, and the crosslinking could not proceed, and the magnetic loss (1GHz) was as low as 0.5.

Comparative example 2

An electromagnetic wave absorbing material was obtained and evaluated in the same manner as in example 1 except for using a soft ferrite surface-treated with epoxytrimethoxysilane which is a functional group-based silane compound. The evaluation results are shown in table 1. The heat resistance is low for 1000 hours or less.

Comparative example 3

An electromagnetic wave absorbing material was obtained and evaluated in the same manner as in example 1, except that the silicone gel was not crosslinked. The evaluation results are shown in table 1. The same test results of the diffusion phenomenon (bleeding phenomenon) as in example 1 were: the substance placed in a horizontal state cannot hold its periphery at its original position, and a diffusion phenomenon (bleeding phenomenon) can be confirmed. Further, the dripping phenomenon can be confirmed even with the substance placed in the inclined state. Further, since the crosslinking was not completed, a change with time could be observed.

Comparative example 4

An electromagnetic wave absorbing material was obtained and evaluated in the same manner as in example 2, except that the silicone gel was not crosslinked. The evaluation results are shown in table 1. As in comparative example 3, the diffusion phenomenon (bleeding phenomenon), dripping phenomenon, and change with time were confirmed.

TABLE 1

				Examples		Comparative example
										1	2	1	2	3	4
				Composition of electromagnetic wave absorbing material	Soft ferrites	D50	μm	1～10	1～10							1～10	1～10	1～10	1～10
Surface treating agent	-	Methyltrimethoxysilane	Methyltrimethoxysilane							Without treatment	Epoxy trimethoxy silane	First of allTrimethoxysilanes	Methyltrimethoxysilane
						pH after surface treatment		＜8.2	＜8.2					＞8.5	＜8.2	＜8.2	＜8.2
Compounding amount	wt％	83	50							20 (Limit)	83	83	50
						Flat soft magnetic metal powder	D50	μm	-					8～42	-	-	-	8～42
Compounding amount	wt％	0	25		0					0	0	25
							Ferroferric oxide	D50	μm				0.1～0.4	0.1～0.4	-	0.1～0.4	0.1～0.4	0.1～0.4
Compounding amount	wt％	5	5		0	5				5	5
								Silicone	Consistency of			-	130	130	130	130	130	130
Compounding amount	wt％	12	20		80	12	12			20
									Evaluation of electromagnetic wave absorbing Material		Loss of magnetism (FIG. 1)		μ″	A	B	0.5(1GH)	-	-	-
Volume resistance		Ωm	2×1011	107	-	2×1011	-	-
										Dielectric breakdown strength		KV/mm	4.5	0.2	-	4.5	-	-
Coefficient of thermal conductivity		W/m·K	1.2	0.8	-	1.2	-	-
										Specific gravity of		-	2.8	3.0	-	2.8	-	-
Consistency of		-	80	50	-	80	-	-
										Flame retardancy (UL94)		-	Corresponding to V-0	Corresponding to V-0	-	Corresponding to V-0	-	-
Heat resistance (150 ℃ C.)		Hr	＞1000	＞1000	-	＜1000	-	-
										Diffusion and dripping phenomena		-	Is free of	Is free of	-	Is free of	Is provided with	Is provided with

Industrial applicability of the invention

The extrudable crosslinked grease-like electromagnetic wave absorbing material of the present invention can uniformly encapsulate the electromagnetic wave absorbing filler in the crosslinked silicone gel, and therefore, even when a large amount of the electromagnetic wave absorbing filler is incorporated, the electromagnetic wave absorbing material does not cause the problem of separation or uneven distribution, and can improve the electromagnetic wave absorbing performance. Further, the material can be put into a container such as a tube or a syringe, and can be extruded with a weak force such that the tube is gripped by a hand or a syringe piston is pushed by the force of air, and can be formed into an arbitrary shape by applying a force after extrusion, and the material does not cause a diffusion phenomenon (a bleeding phenomenon) in a machine to which the material is applied, and has a property of retaining an original shape (self-shape retention property) as long as it is left as it is even when it is held in an inclined state, and has a characteristic of being less changed with time because it is a crosslinked material. Therefore, unnecessary electromagnetic waves around the opening of the case can be absorbed by simple thin coating, and the emission efficiency of noise can be reduced, which can significantly reduce the cost compared to the conventional method in which secondary processing and complicated bonding operation are required.

Claims (12)

1. An extrudable crosslinked grease-like electromagnetic wave absorbing material, which is a crosslinked grease-like electromagnetic wave absorbing material in which an electromagnetic wave absorbing filler is dispersed in a crosslinked silicone gel, the crosslinked grease-like electromagnetic wave absorbing material being characterized in that: the fluid, self-retaining silicone gel has a shape retention property, and contains 200 to 800 parts by weight of a filler for electromagnetic wave absorption per 100 parts by weight of the crosslinked silicone gel.

2. The extrudable crosslinked grease-like electromagnetic wave absorbing material as claimed in claim 1, wherein the consistency of the crosslinked silicone gel is 50 to 200(JIS K22201/4 Cone).

3. The extrudable crosslinked grease-like electromagnetic wave absorbing material as claimed in claim 1 or 2, wherein the filler for electromagnetic wave absorption is a mixture of an electromagnetic wave absorber and a flame retardant.

4. The extrudable crosslinked grease-like electromagnetic wave absorbing material as claimed in claim 3, wherein the electromagnetic wave absorber is a soft ferrite and/or flat soft magnetic metal powder surface-treated with a non-functional group-based silane compound.

5. The extrudable crosslinked grease-like electromagnetic wave absorbing material as claimed in claim 4, wherein the soft ferrite surface-treated with the non-functional group-based silane compound is a soft ferrite surface-treated with dimethyldimethoxysilane or methyltrimethoxysilane.

6. The extrudable crosslinked grease-like electromagnetic wave absorbing material as claimed in claim 4 or 5, wherein the pH of the soft ferrite surface-treated with the non-functional group-based silane compound is 8.5 or less.

7. The extrudable crosslinked grease-like electromagnetic wave absorbing material as claimed in any one of claims 3 to 6, wherein the flame retardant is magnetite.

8. A container filled with and sealed therein the extrudable crosslinked grease-like electromagnetic wave absorbing material as claimed in any one of claims 1 to 7.

9. Container according to claim 8, characterized in that it is in the shape of a syringe or a tube.

10. The method for producing a container according to claim 8 or 9, wherein, when the electromagnetic wave absorbing filler is dispersed in the crosslinked silicone gel, the crosslinked grease-like electromagnetic wave absorbing material is obtained by heating during or after mixing the raw material substance of the crosslinked silicone gel and the electromagnetic wave absorbing filler, and then the crosslinked grease-like electromagnetic wave absorbing material is filled and sealed in the container.

11. The method for producing a container according to claim 8 or 9, wherein, when the electromagnetic wave absorbing filler is dispersed in the crosslinked silicone gel, a mixed solution obtained by mixing a raw material of the crosslinked silicone gel and the electromagnetic wave absorbing filler is filled and sealed in the container, and then the entire container is heated to crosslink the silicone gel in the container.

12. A method for absorbing unnecessary electromagnetic waves, characterized in that a crosslinked grease-like electromagnetic wave absorbing material filled and sealed in the container according to claim 8 or 9 is applied in the form of a film to the periphery of a heat-radiating opening of a case, thereby suppressing the radiation of unnecessary electromagnetic waves from the heat-radiating opening.