JP4725849B2 - Vibration reducing material - Google Patents

Description

The present invention relates to a vibration reducing film such as a vibration damping material or a soundproof material.

Vibration reduction technology such as vibration suppression or soundproofing is widely used in daily life, and examples thereof include sound insulation partitioning of building structures, soundproofing of water piping, and soundproofing and vibration suppression of vehicles and electromechanical devices. In particular, electronic devices are required to shield electromagnetic noise in addition to suppressing vibration noise generated from a motor or the like. As conventionally known ones, JP-A-6-81187, JP-A-5-110284, JP-A-5-87186, JP-A-4-266642, JP-A-4-849221, A technique disclosed in Japanese Utility Model Laid-Open No. 61-174700 may be mentioned.

First, the technology disclosed in Japanese Patent Laid-Open No. 6-81187 relates to a metal foam, and this metal foam is used as an acoustic insulating material or a sound insulating material, and is a polyurethane provided with a conductive surface film. The foam is metal-plated with nickel.

Next, the technique disclosed in Japanese Patent Laid-Open No. 5-110284 discloses that a conductive foamed resin body is attached to a ventilation window of an electronic device such as a printer device or a terminal device to perform a soundproof shield and an electromagnetic wave shield. This technology makes the performance of electronic devices and terminal devices excellent. This conductive foamed resin body is a polyurethane foam plate-shaped foam made conductive by metal plating, and is attached to the above equipment by a conductive adhesive or double-sided conductive tape.

Next, the technology disclosed in Japanese Patent Laid-Open No. 5-87186 relates to soundproofing materials such as various mechanical devices and building structures, and vibration damping materials used as vibrationproofing materials. A conductive paint is applied to a film-like piezoelectric material. Examples of the piezoelectric material include polyvinylidene fluoride (PVDF), a copolymer of PVDF and trifluoroethylene, a copolymer of vinylidene cyanide and vinyl acetate, and examples of the conductive material include metals and metal oxides. Or those containing conductive particles such as carbon. Specifically, this vibration damping material has a Kureha KF piezo film (PVDF) made by Kureha Chemical Co., Ltd. having a thickness of 30 μm and a thickness of 20 μm on the surface of a polypropylene film having a thickness of 0.2 mm. The antistatic paint is applied. In addition, as an example of using a piezoelectric film that is inexpensive and easy to form, damping materials using a piezoelectric film using a polyamide polymer have also been proposed (for example, Japanese Patent Application Laid-Open No. 8-305369, Japanese Patent Application Laid-Open No. No. 9-309962). However, in order to express the piezoelectricity in the film, a polarization process is required. Therefore, a special apparatus is required for the production, and there is a problem that the production cost increases.

Also disclosed are compositions comprising a polymer material and a piezoelectric powder material as main components (see, for example, JP-A-60-51750 and JP-A-3-188165). A composition of a polymer material and a piezoelectric powder converts vibration energy into electric energy by piezoelectricity, consumes the generated electric energy by Joule heat, and absorbs and attenuates vibration. However, in this composition, sufficient vibration damping properties cannot be obtained unless the piezoelectric particles are blended so as to contain 50% by mass or more. However, when blended in such a manner, the fluidity in the molten state becomes low, and kneading and molding become difficult. Further, since ceramics such as lead zirconate titanate and barium titanate are used for the piezoelectric particles, there is a disadvantage that the mass is increased.

Next, the technology disclosed in Japanese Patent Laid-Open No. 4-266742 relates to a porous material and a soundproof panel having both electromagnetic shielding properties and antistatic properties. This is a granular material such as expanded polystyrene beads that has an appropriate gap ratio, and a semi-molten solidified layer and a molten solidified layer are simultaneously formed on the front and back surfaces, and heated and pressurized. In addition, a fiber sheet such as a nonwoven fabric is laminated. The publication also discloses a material in which a breathable metal sheet or a conductive fiber web is interposed between the expanded polystyrene bead layers.

Next, the technique disclosed in Japanese Patent Laid-Open No. Hei 4-84921 relates to a technique for silencing noise generated when a vacuum cleaner is used. Noise such as intake / exhaust noise is detected in the main body or pipe, and the noise is canceled out. According to this, the muffling unit includes a sound pressure detection unit, an electric signal analysis processing unit, and a piezoelectric film.

Furthermore, the technique disclosed in Japanese Patent Application Laid-Open No. 61-174700 relates to an electronic device provided with noise prevention means, and according to this, metal is plated on the cooling ventilation window as noise prevention means. The foamed resin body is formed as an electromagnetic wave shielding layer. In this electromagnetic wave shielding layer, the foamed resin body is formed of a polyurethane resin having a thickness of 1 mm, and the metal plating layer is formed of a nickel film having a thickness of 1 μm.

Further, a damping material in which an active ingredient that increases the amount of dipole moment is included in a polymer base material is also disclosed (see, for example, Japanese Patent Nos. 3318593 and 3192400). However, the active ingredient used in this material is a low-molecular compound, and has a drawback that it is oozed out from the base material during use and the performance is lowered.
JP-A-6-81187 Japanese Patent Laid-Open No. 5-110284 JP-A-5-87186 JP-A-8-305369 Japanese Patent Laid-Open No. 9-309962 JP-A-60-51750 Japanese Patent Laid-Open No. 3-188165 JP-A-4-266742 Japanese Patent Laid-Open No. 4-84921 JP 61-174700 A Japanese Patent No. 3318593 Japanese Patent No. 3192400

An object of the present invention is to provide a material that is mainly made of a polymer resin film, can be easily manufactured, is lightweight, and has a higher vibration reduction property.

As a result of various studies to solve the above problems, the inventor was able to obtain a film having vibration reducing properties by packing rigid particles in a void while stretching. The invention according to claim 1 is a vibration reducing material, characterized in that rigid particles are packed in a void expanded in the craze region of the polymer resin film in which the craze region is formed.

The invention according to claim 2 is the vibration reducing material according to claim 1, wherein the rigid particles are metal, alloy, or carbon rigid particles.

The invention according to claim 3 is a vibration reduction of a polymer resin film in which a craze region is formed, in which a conductive material is filled in an expanded void in the craze region, and a conductive layer is laminated on both sides of the polymer resin film. A vibration reducing material, wherein the polymer resin film has piezoelectricity.

When the film is subjected to vibration by packing the rigid particles in the void while stretching, one is caused by friction caused by rubbing due to the vibration of the rigid particles, and the other is the result of packing and fixing the particles in the void. Large vibration damping can be brought about by the change to the plastic region. Furthermore, the vibration damping effect by the piezoelectric effect can be added by making the film piezoelectric and making the particles and the surface conductive.

Hereinafter, the present invention will be described in more detail with reference to embodiments. Of course, the present invention is not limited to the following embodiments.

The polymer resin film in which the craze region is formed can be produced by a method disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-258010 or Japanese Patent Application Laid-Open No. 6-82607. That is, the crazing forming apparatus shown in FIG. 1 is roughly composed of a crazing processor 13 composed of a support 11 and a guide roller 12 having a sharp edge 11a at the tip, and a tension applying mechanism (not shown). Consists of. The polymer resin film 14 held in tension is brought into contact with the edge 11a of the support, and the polymer resin film 14 is locally bent to form a deformation region. By gradually moving the film relative to the film, the craze region can be continuously formed in a stripe shape in a direction substantially perpendicular to the moving direction. A schematic view of the obtained craze is shown in FIG.

The width of the crazed region formed in a stripe shape is preferably 0.5 to 100 μm, and more preferably 1 to 50 μm. The striped shape means a state in which crazed regions are formed at intervals of 0.1 to 1,000 μm, preferably 1 to 800 μm.

The resin material used here may be any polymer resin material that forms a film. For example, polyolefins such as polyethylene, polypropylene, polybutylene and polyisoprene, polyamides such as nylon-6 and nylon-6,6, polyethylene terephthalate, Polyester such as polybutylene terephthalate, polyvinyl butyral, polyvinyl alcohol, polystyrene, polyvinylidene fluoride, polyimide, polyphenylene sulfide, polyether ether ketone, and the like can be used.

In the invention of the present application, the rigid particles are packed in the voids of the polymer resin film (hereinafter referred to as “craze film”) in which the craze region is formed in this manner. It is a characteristic vibration reducing material. FIG. 3 is a schematic view of a state in which rigid particles are packed in an expanded void in the craze region. When stretched, the void expands, and when the particles are packed therein, the void remains expanded even when the tension is removed, thereby reducing vibration. That is, when the stress-strain curve when the polymer material is pulled is viewed, the material is elastically deformed at the initial stage of tension, but when further tension is applied, the material is plastically deformed. The state in which the void is fixed by extending to the craze generation region of the polymer resin film corresponds to this plastic region and increases vibration damping. Further, when the polymer resin film is vibrated, the rigid particles in the void rub against each other in the void, and the vibration is attenuated by the friction. By the action of both, the polymer resin film in which the rigid particles are packed in the void can reduce vibration.

In order to pack the rigid particles into the voids in the craze region, the voids are first expanded. This is expanded by causing the film to craze or once the film is crazed and then stretched. In this state, the dispersion liquid of rigid particles is infiltrated into the voids in the craze region of the craze film. Specifically, a method of immersing in a dispersion of rigid particles, a method of applying a dispersion of rigid particles by a roller or a doctor, or a method of applying by a spray or the like can be exemplified. A dispersion of rigid particles can be obtained by dispersing rigid particles in a dispersion medium such as toluene, acetone, ethanol, and water.

In the penetration of the dispersion of rigid particles by immersion, for example, if the voids in the crazing region do not penetrate in the thickness direction of the craze film, the rigid particle dispersion is made by curving so that the voids in the craze film are on the outside. Penetration is also effective in reducing time. In order to curve the craze film, for example, a method of winding around the surface of a cylinder can be employed.

In order to infiltrate the dispersion liquid of rigid particles into the voids in the craze region of the craze film by application, the dispersion liquid of rigid particles may be applied from one side or both sides of the craze film. In application by a roller or doctor, the dispersion of rigid particles is placed in the void in the craze area while moving the roller or doctor relative to the craze film so as not to damage the surface of the craze film. If it press-fits, penetration will be possible in a short time. When applying a dispersion of rigid particles on one side of a craze film that has many voids penetrating through a roller, doctor, or spray, the pressure on the opposite side of the coating surface may be reduced. If the pressure is applied from the application surface side, rapid penetration into a deeper portion becomes possible.

In this way, if the dispersion liquid of rigid particles is infiltrated into the void and then the dispersion liquid is dried, the rigid particles remain and the rigid particles are packed. Even if the tension that has been removed from the stretching machine before the drying and the voids are expanded is removed, the voids are compressed by the stress of the resin and filtered, and the rigid particles remain. On the other hand, it is possible to more reliably pack the rigid particles in the void by stretching the dispersion until the drying proceeds and then compressing the void by the stress of the resin except for the tension that has expanded the void. By repeating the infiltration and drying, a larger amount of particles can be packed.

As described above, the rigid particles of the present application secure void spaces against the elasticity of the resin, and it is sufficient that the elastic modulus of the particles is larger than the elastic modulus of the resin. Although the particle size is determined relative to the void size, particles of several nanometers to several microns may be used. Usually, particles of inorganic material can be preferably used. For example, any material such as colloidal silica, alumina, silica alumina, calcium carbonate, titanium oxide and the like can be used as long as they match.

When a magnetic material is used as the rigid particles, vibration damping can be further enhanced by the magnetic action between the particles. For example, Fe, Co, Ni, rare earth cobalt alloy, neodymium iron boron alloy, manganese-aluminum magnet, Alnico magnet containing metals such as Al, Ni, Co, Cu, Sendust (Fe-Si-Al alloy), Permalloy (Ni-Fe alloy), manganese-bismuth magnet, carbonyl iron, amorphous magnetic alloy having Fe group or Co group, spinel type ferrite (MnFe ₂ O ₄ , Fe ₃ O ₄ , Y-Fe ₂ O ₃ , NiZnFe ₄ O ₆ , ZnFe ₂ O _4, etc.), garnet type ferrite (Y ₃ Fe ₂ (FeO ₄ ) ₃ , Sm ₃ Fe ₂ (FeO ₄ ) 3 etc.), magnetoplumbite type ferrite (BaO · 6Fe ₂ O) _{3, SrO · 6Fe 2 O 3} , PbO · 6Fe 2 O 3 , etc.) ferritic metal oxide magnetic material such as, other than the ferrite metal oxide magnetic Body (CrO _2, EuO, etc.), Recently, organic compounds actively developed research is being carried out, the organic metal, and a ferromagnetic material composed of an organic metal complex. Among these, spinel-type, garnet-type, and magnetoplumbite-type ferrite-based metal oxide magnetic materials, rare-earth cobalt alloy magnetic materials, neodymium iron boron-based alloy magnetic materials, and the like can be given.

When adding conductivity to reduce vibration and shield electromagnetic waves, conductive rigid particles such as metal, alloy, or carbon are used as the rigid particles. Metal rigid particles can be precious metals such as gold, platinum, palladium, rhodium, iridium, ruthenium, silver, and base metals such as copper, nickel, iron, chromium, aluminum, zinc, titanium, etc. When the thickness is reduced, the surface area increases, and base metals are easily oxidized. Fine particles of a noble metal such as gold, platinum, palladium, rhodium, iridium, ruthenium, silver or a metal or alloy of copper are preferable. In particular, a nanocolloid obtained by reducing a metal salt in an aqueous surfactant solution has a particle size of 2 nm to 10 nm and is a size that can be packed into a void in a crazing region, and can be preferably used.

Carbon can also be used as the conductive rigid particles. However, normal carbon black has a structure of aggregates of 200 to 1000 nm in which basic particles of 20 to 100 nm are aggregated. Simply applying the carbon black dispersion as it is to the craze film does not sufficiently penetrate the void, and remains in the vicinity of the surface of the film, so that sufficient conductivity cannot be obtained. Further, there is a disadvantage that carbon black or the like becomes powdery and floats on the film surface during use or falls off the film.

The carbon of the present application was used by nano-dispersing carbon in view of such disadvantages. That is, the carbon black organic solvent dispersion is sonicated, or the carbon black organic solvent dispersion is collided at high speed with a high-pressure jet emulsification method or passed between blades rotating at high speed. The carbon black aggregate can be finely dispersed by giving a strong shearing force to the black aggregate. By making the carbon black aggregate into a so-called nanosize having an average particle size of 1 μm or less, preferably an average particle size of 0.1 μm or less, particularly preferably an average particle size of 20 nm to 700 nm, it can be easily packed in a void and has high conductivity. Sex can be obtained.

Carbon types include conductive carbon such as ketjen black and acetylene black, thermal carbon such as FT and MT, soft carbon such as FEF, GPF and SRF, and hard carbon such as SAF, ISAF and HAF, depending on the required particle size. Can also be used.

When a rigid particle is packed in a void expanded in the craze region of the polymer resin film in which the craze region is formed, the size of the particle is small and the surface area is large, and the polymer resin film is easily oxidized. In order to cope with this, it is one method to use noble metal fine particles, but the opening in the polymer resin film leading to the outside of the void may be covered with an airtight layer.

The airtight layer should just cover the void surface of the polymer resin film. For example, a film in which metal powder or conductive carbon is bonded with a binder is laminated. A paint in which metal powder or conductive carbon is bonded with a binder is applied. A conductive monomer is applied and polymerized. Or the method of vapor-depositing a metal or carbon is mentioned.

In addition to conductive particles, piezoelectric particles may be used as rigid particles packed in the void. This is because charges are generated on the particle surface by vibration of the film, and vibration damping is enhanced by Joule heat when flowing through the surface conductive or intervening conductive particles. For example, a piezoelectric ceramic represented by PZT is a ferroelectric material having a perovskite crystal whose general composition formula is expressed by ABO ₃ . PZT is represented by the composition formula Pb (Zr, Ti) O ₃ and is composed of a solid solution of ferroelectric PbTiO ₃ and antiferroelectric PbZrO ₃ . As other piezoelectric ceramics, BaTiO ₃ , PbTiO ₃ and (Pb, La) (Zr, Ti) O ₃ are representative.

Furthermore, the inventor has found that the vibration damping property is further improved by using a piezoelectric film as the polymer resin film in which the crazed region is formed. As shown in FIG. 4, the craze region 1 is formed in the piezoelectric film 20, and a conductive material containing rigid particles is filled in the void. The vibration reducing material of the present invention can be obtained by laminating the conductive layer 22 on both surfaces of the piezoelectric film 20 filled with the conductive material. Electric charges are generated on the surface of the piezoelectric film 20 by the vibration, and the electric charges collected through the conductive layer 22 generate Joule heat by energizing the conductive material in the craze region 1, thereby reducing vibration. Combined with the vibration reduction effect of rigid particles packed in the craze region, a large vibration reduction effect is derived.

The piezoelectric film used here may be any polymer resin film that exhibits piezoelectricity. For example, polyvinylidene fluoride (PVDF), a copolymer of PVDF and trifluoroethylene, vinylidene cyanide and vinyl acetate. Optical activity such as copolymers with olefins, ferroelectric polyamides, biopolymers such as polypeptides and cellulose derivatives, and synthetic polymers such as polylactic acid and polyhydroxybutyric acid obtained by polymerizing monomers with optical activity The polymer etc. which have are mentioned. If necessary, these films are subjected to polarization treatment, and then crazing treatment to form crazed regions and generate voids.

The conductive material that fills the void includes rigid particles. Conductive rigid particles such as conductive metals or alloys or carbon, magnetic particles, piezoelectric particles, and other rigid particles can be used. Conductive rigid particles or a conductive polymer that imparts conductivity are added to this and filled into the void as a conductive material.

Conductive layers are provided on both surfaces of the obtained void-filled particle-filled piezoelectric film. The conductive layer only needs to cover the void surface of the polymer resin film. For example, a film in which metal powder or conductive carbon is bonded with a binder is laminated. A paint in which metal powder or conductive carbon is bonded with a binder is applied. A conductive monomer is applied and polymerized. Or the method of vapor-depositing a metal or carbon is mentioned. By providing a conductive layer on the surface, the filled particles are shielded from oxygen in the outside air, and particles having a large surface area such as metal fine particles can be used stably.

When the obtained vibration reducing material is mounted on an electronic device or the like, the film can be formed by forming a space and shielding the sound, instead of winding the film in contact with the device. The film thickness is preferably in the range of 20 to 300 μm, but may be 300 μm or more as long as the crazing treatment can be performed.

Examples of the present invention will be described in more detail below with reference to the drawings. However, these are representative examples, and the present invention is not limited to these examples.

[Reference example]
As the material film, a 50 μm-thick uniaxially stretched film (KYNAR720, manufactured by Mitsubishi Chemical Corporation) formed by a T-die method of polyvinylidene fluoride (PVDF) was used. This film was subjected to a crazing treatment at room temperature with a treatment tension of 16 N / cm applied to the crazing treatment machine of FIG.

[Example 1]
The crazed film of the reference example is turned by hand and fixed on a stretching machine so that it does not sag, and a platinum nanocolloid concentrate “IASO” manufactured by Seatec Co., Ltd. is applied while applying a tension of 8 N / cm. It quickly penetrated into the craze region by capillary action. Subsequently, it was dried by applying hot air, and the tension was removed after drying.

[Example 2]
<Adjustment of dispersion>
1 part of ketjen black is mixed with 20 parts of toluene to prepare a coarse dispersion, and the coarse dispersion is subjected to ultrasonic treatment for 30 minutes using a probe type ultrasonic homogenizer (ULTRASONIC DISUPTOR UR-200P, Tommy Seiko). By applying, a nano-dispersed carbon liquid was obtained. The crazed film of the reference example is turned by hand and fixed on a stretching machine so that it does not sag, and the nano-dispersed carbon liquid is applied while applying a tension of 20 N / cm. It quickly penetrated into the craze region by capillary action. Subsequently, it was dried by applying hot air, and the tension was removed after drying.

[Example 3]
The craze film of the reference example is turned by hand and fixed to a stretching machine so that it does not sag, and a colloidal silica “Snowtex” manufactured by Nissan Chemical is applied while applying a tension of 20 N / cm. It quickly penetrated into the craze region by capillary action. Subsequently, it was dried by applying hot air, and the tension was removed after drying.

[Example 4]
When the conductive film filled with the platinum nanocolloid of Example 1 was rotated by hand and fixed on a stretching machine and pyrrole was applied to the surface side of the film, it quickly penetrated into the crazing region by capillary action. Next, after the monomer on the film surface was wiped off, the film was dried at room temperature, and an ethanol solution of 0.1 mol iron (III) chloride was applied to the film surface side to polymerize pyrrole.

According to the present invention, the rigid particles are packed in the voids in the crazing region, and thus the vibration damping property and the function of the conductive and hence the electromagnetic wave shielding can be achieved by using the conductive rigid particles. As a result, it can be used not only for vibration control and soundproofing of automobiles, buildings, piping, etc., but also can be effectively applied to soundproofing and electromagnetic wave shielding of personal computers, DVD drives, and other electronic acoustic devices.

Schematic diagram of craze film production Schematic diagram of craze Schematic diagram of rigid particles packed in voids Schematic diagram of piezoelectric vibration reduction film

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Craze area | region 3 Molecular bundle 4 Void 11 Support body 14 Polymer resin film 20 Piezoelectric film 22 Conductive layer 30 Vibration reducing material

Claims (3)

A vibration reducing material comprising a polymer resin film having a craze region formed therein, and rigid particles packed in voids expanded in the craze region. The vibration reducing material according to claim 1, wherein the rigid particles are conductive rigid particles of metal, alloy, or carbon. A vibration reducing material comprising a polymer resin film formed with a craze region, in which a conductive material is filled in voids expanded in the craze region, and a conductive layer is laminated on both sides of the polymer resin film. A vibration reducing material wherein the molecular resin film has piezoelectricity.

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