WO2014105979A1 - Production method of curable organopolysiloxane composition for transducers - Google Patents

Production method of curable organopolysiloxane composition for transducers Download PDF

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Publication number
WO2014105979A1
WO2014105979A1 PCT/US2013/077855 US2013077855W WO2014105979A1 WO 2014105979 A1 WO2014105979 A1 WO 2014105979A1 US 2013077855 W US2013077855 W US 2013077855W WO 2014105979 A1 WO2014105979 A1 WO 2014105979A1
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WIPO (PCT)
Prior art keywords
curable organopolysiloxane
composition
kneading
production method
organopolysiloxane composition
Prior art date
Application number
PCT/US2013/077855
Other languages
French (fr)
Inventor
Toru Imaizumi
Madoka KAJIUCHI
Harumi Kodama
Kent R. LARSON
Wataru Nishiumi
Masayuki Onishi
Kouichi Ozaki
Kuniyoshi TAKAYANAGI
Original Assignee
Dow Corning Corporation
Dow Corning Toray Co., Ltd.
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Publication date
Application filed by Dow Corning Corporation, Dow Corning Toray Co., Ltd. filed Critical Dow Corning Corporation
Publication of WO2014105979A1 publication Critical patent/WO2014105979A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
    • C08L83/04—Polysiloxanes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
    • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/50—Details of extruders
    • B29C48/505—Screws
    • B29C48/57—Screws provided with kneading disc-like elements, e.g. with oval-shaped elements
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/20—Compounding polymers with additives, e.g. colouring
    • C08J3/201—Pre-melted polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/20—Compounding polymers with additives, e.g. colouring
    • C08J3/203—Solid polymers with solid and/or liquid additives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/20—Compounding polymers with additives, e.g. colouring
    • C08J3/22—Compounding polymers with additives, e.g. colouring using masterbatch techniques
    • C08J3/226—Compounding polymers with additives, e.g. colouring using masterbatch techniques using a polymer as a carrier
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/56—Organo-metallic compounds, i.e. organic compounds containing a metal-to-carbon bond
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
    • C09D183/04—Polysiloxanes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B7/00—Mixing; Kneading
    • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
    • B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
    • B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
    • B29B7/46—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft
    • B29B7/48—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws
    • B29B7/482—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws provided with screw parts in addition to other mixing parts, e.g. paddles, gears, discs
    • B29B7/483—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws provided with screw parts in addition to other mixing parts, e.g. paddles, gears, discs the other mixing parts being discs perpendicular to the screw axis
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
    • C08G77/04—Polysiloxanes
    • C08G77/12—Polysiloxanes containing silicon bound to hydrogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
    • C08G77/04—Polysiloxanes
    • C08G77/20—Polysiloxanes containing silicon bound to unsaturated aliphatic groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2383/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen, or carbon only; Derivatives of such polymers
    • C08J2383/04—Polysiloxanes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2483/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen, or carbon only; Derivatives of such polymers
    • C08J2483/04—Polysiloxanes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C08K2003/2237—Oxides; Hydroxides of metals of titanium
    • C08K2003/2241—Titanium dioxide

Definitions

  • the present invention relates to a production method of a curable organopolysiloxane composition capable of use with advantage for transducers.
  • the present invention provides a production method of a curable organopolysiloxane composition for which the
  • organopolysiloxane cured article formed by curing is used as an electrically active silicone elastomer material capable of use as the dielectric layer or electrode layer of a transducer.
  • the present invention particularly relates to a production method of a curable organopolysiloxane composition having electrical characteristics and mechanical characteristics suitable for a material used as a dielectric material, and, further, particularly for use as a dielectric layer of a transducer.
  • the present invention further relates to a production method for an electrically active polymer material formed using a curable organopolysiloxane composition, and to a component of a transducer containing this electrically active polymer material.
  • A. G. Benjanariu, et. al. indicated that dielectric polymers are potential materials for artificial muscles (A. G. Benjanariu, et. al., "New elastomeric silicone based networks applicable as electroactive systems," Proc. of SPIE vol. 7976 79762V-1 to 79762V-8 (2011 )). Here, they showed the physical characteristics of a material having a unimodal or bimodal network formed with an addition-curable silicone rubber. To form this silicone rubber, a linear chain
  • poly(dimethylsiloxane) (PDMS) polymer having vinyl groups is crosslinked using a short chain organohydrogensiloxane having 4 silicon-bonded hydrogen atoms as the crosslinking agent.
  • PDMS poly(dimethylsiloxane)
  • an actuator that sandwiches a dielectric elastomer material, which is an organopolydimethylsiloxane that has been chemically modified by groups functioning as electrical dipoles, between electrodes, the modification being performed by bonding the groups to polydimethylsiloxane using a crosslinking agent.
  • Non-patent Document 1 "New elastomeric silicone based networks applicable as electroactive systems," Proc. of SPIE vol. 7976 79762V-1 to 79762V-8 (2011 )
  • Non-patent Document 2 Actuator 2012, 13th International Conference on New Actuators, Bremen, Germany, 18-20 June 2012, pp. 374 to 378
  • An object of the present invention is to provide a production method of a curable
  • organopolysiloxane composition capable of producing a cured article that can be used as a transducer and provided with excellent mechanical characteristics and/or electrical
  • Another object of the present invention is to provide a production method of a curable organopolysiloxane composition capable of realizing a high energy density by providing excellent mechanical characteristics and/or electrical characteristics, and particularly a high specific dielectric constant, high dielectric breakdown strength, and low Young's modulus; able to achieve durability and a practical displacement amount due to excellent mechanical strength (i.e. tensile strength, tearing strength, elongation, or the like) in the case of use as a dielectric layer of a transducer; and able to produce a cured article capable of use as a material for use in transducers.
  • excellent mechanical strength i.e. tensile strength, tearing strength, elongation, or the like
  • an object of the present invention is to provide a method for production of a curable organopolysiloxane composition for transducers that is able to readily obtain an intermediate raw material of a curable organopolysiloxane composition for transducers (i.e. intermediate raw material that is a silicone rubber compound containing the raw material polymer blended with a high concentration of various types of fillers, sometimes referred to hereinafter as a "master batch” or "silicone elastomer base"), so that when the intermediate raw material is used, the production efficiency and the performance of the obtained cured product are excellently improved.
  • intermediate raw material i.e. intermediate raw material that is a silicone rubber compound containing the raw material polymer blended with a high concentration of various types of fillers, sometimes referred to hereinafter as a "master batch” or "silicone elastomer base
  • an object of the present invention is to provide a method for production of a curable organopolysiloxane composition for transducers capable of advantageous production from the standpoint of a component used for transducers in that a uniform sheet-like cured product may be obtained, a thin film may be produced, electrical characteristics or mechanical characteristics of the obtained sheet-like cured product are excellent, and handling ability is excellent for lamination or the like.
  • the present invention was achieved by the discovery by the inventors that the present invention can solve the aforementioned problems by a production method of a curable organopolysiloxane composition for transducer use comprising a step of kneading a composition for kneading including: a curable organopolysiloxane, and at least one type of filler, wherein the kneading is performed using an extruder or kneading apparatus.
  • the composition for kneading further include (D) dielectric inorganic fine particles having specific dielectric constant at 1 kHz greater than or equal to 10 at room temperature as the at least one type of filler. More preferably, the composition further includes at least one type of surface treatment agent.
  • the extruder or kneading apparatus is preferred to be at least one mechanical means selected from the group consisting of twin screw extruders, twin screw kneaders, and single screw blade-type extruders, and more preferred to be a twin screw extruder having a device free volume as defined below that is at least 5,000 (L/hr), is at least 7,500 (L/hr), or is at least 10,000 (L/hr).
  • Free volume void cross-sectional area of the apparatus (mm2) ⁇ screw pitch (mm) ⁇ rotation rate (rpm) ⁇ 60/1 ,000,000 (L/hr)
  • the filler is well dispersed in the curable organopolysiloxane, and it is thus possible to produce a member for transducers having good electrical characteristics or mechanical characteristics.
  • the production method of a curable organopolysiloxane composition for transducer use of the present invention is characterized by comprising a step of kneading a composition for kneading including: a curable organopolysiloxane, and at least one type of filler, wherein the kneading is performed using an extruder or kneading apparatus.
  • the production method it is possible to produce a member for transducers having good quality when film thickness is reduced.
  • the use of the production method it is possible to readily obtain an intermediate raw material in which various types of fillers are blended at high concentration in the curable organopolysiloxane (i.e. raw material), and the production of the final composition may be readily accomplished.
  • the curable organopolysiloxane composition produced by and according to the present invention is a composition for curing to produce a member for transducers.
  • organopolysiloxane composition produced according to the present invention particularly may have filler dispersed at high concentration in the curable organopolysiloxane.
  • This type of curable organopolysiloxane composition may itself be used to produce a member for transducers by curing by heating or the like, or alternatively, this type of curable organopolysiloxane composition may be used as an intermediate raw material (i.e. master batch, silicone elastomer base or silicone rubber compound) for production of a member for transducers.
  • the curable organopolysiloxane composition as an intermediate raw material (master batch, silicone elastomer base or silicone rubber compound)
  • blending with another component such as a curable organopolysiloxane or the like is readily possible at a desired formulation using of a desired kneading apparatus, and thus the production efficiency is excellent.
  • curable organopolysiloxane No particular limitation is placed on the curable organopolysiloxane as long as the curable organopolysiloxane is curable by condensation curing reaction, addition curing reaction, peroxide compound curing reaction, photocuring reaction, or by drying and solidification upon removal of a diluent solvent.
  • the curable organopolysiloxane may be used as a combination of two or more types of different curable organopolysiloxanes.
  • the curable organopolysiloxane curing by an addition curing mechanism is exemplified by organohydrogenpolysiloxanes having at least 2 silicon-bonded hydrogen atoms in a molecule and/or organopolysiloxanes having at least 2 alkenyl groups in a molecule.
  • the curable composition further comprises a hydrosilylation reaction catalyst.
  • the organopolysiloxane curable by condensation curing mechanism is exemplified by diorganopolysiloxanes that are liquid at room temperature and having molecular terminals capped by silanol groups or silicon-bonded hydrolyzable groups, or partially hydrolyzed condensates of organosilanes having silicon-bonded hydrolyzable groups.
  • said diorganopolysiloxane or said partially hydrolyzed condensate of organosilane further includes an organosilane or organosiloxane type crosslinking agent having a sufficient amount of silicon-bonded hydrolyzable groups for crosslinking these components.
  • the curable composition further comprises a condensation reaction promotion catalyst.
  • the curable organopolysiloxane of the present invention may be an organopolysiloxane curable by peroxide compound curing mechanism, for example.
  • the organopolysiloxane is generally exemplified by organopolysiloxane raw rubbers.
  • an organic peroxide compound should be added.
  • the curable organopolysiloxane is a hydrosilylation reaction curable organopolysiloxane. More specifically, the organopolysiloxane may be at least one of (A11 ) at least one type of organohydrogenpolysiloxane having silicon atom-bonded hydrogen atoms at both molecular terminals, a weight fraction of hydrogen atoms being 0.1 to 1 .0% by weight;(A12) at least one type of organohydrogenpolysiloxane having at least 3 silicon atom-bonded hydrogen atoms in a single molecule, a weight fraction of hydrogen atoms being 0.03 to 2.0% by weight; and (A2) at least one type of organopolysiloxane having at least 2 alkenyl groups in a single molecule, a weight fraction of the alkenyl groups being 0.05 to 0.5% by weight.
  • A11 at least one type of organohydrogenpolysiloxane having silicon atom-bonded hydrogen atoms at both
  • the at least one type of filler may be at least one type of filler selected from the group consisting of high dielectric fillers, high electrical conductivity fillers, electrically insulating fillers, and reinforcing fillers.
  • This filler may be used as a single type or as a combination of two or more types.
  • one type or two or more types of filler are preferably used that contain a high dielectric filler and/or high electrical conductivity filler.
  • the filler is preferred to be dielectric fine particles or electrically conductive fine particles, especially, preferred to contain (D) dielectric inorganic fine particles having a specific dielectric constant at 1 kHz of greater than or equal to 10 at room temperature.
  • the preferable dielectric inorganic fine particles is exemplified by one or more types of inorganic fine particles selected from the group consisting of titanium oxide, barium titanate, strontium titanate, lead titanate zirconate, and barium titanate, and composite metal oxides in which the barium and titanium positions of barium titanate are partially replaced by an alkaline earth metal, such as calcium or strontium; zirconium; or rare earth metal such as yttrium, neodymium, samarium, or dysprosium, and titanium oxide and barium titanate are most preferred.
  • an alkaline earth metal such as calcium or strontium
  • zirconium zirconium
  • rare earth metal such as yttrium, neodymium, samarium, or dysprosium
  • titanium oxide and barium titanate are most preferred.
  • the filler component of the entire curable organopolysiloxane composition for transducer use is described in details in later parts.
  • At least one type of surface treatment agent is particularly preferably further kneaded in the composition for kneading in the kneading step.
  • the types of treatment agents is preferred to be an
  • hydrophobizing surface treatment agent more preferably, the surface treatment agent is exemplified by at least one of hydrophobizing surface treatment agent selected from the group consisting of organic titanium compounds, organic silicon compounds, organic zirconium compounds, organic aluminum compounds, and organic phosphorous compounds.
  • hydrophobizing surface treatment agent selected from the group consisting of organic titanium compounds, organic silicon compounds, organic zirconium compounds, organic aluminum compounds, and organic phosphorous compounds.
  • the treatment agent treats the surface of the filler in an efficient manner, dispersibility of the filler is improved, physical properties of the component for transducers produced using this curable organopolysiloxane composition may be effectively improved, and higher filling content and processability of the filler in the intermediate raw material obtained during this kneading step are improved.
  • the curable organopolysiloxane composition produced according to the present invention may further include at least one type of component selected from organopolysiloxanes having a high dielectric functional group, organic compounds having a high dielectric functional group
  • These components may be contained together with said components in the composition for kneading, and the mixture may be kneaded using an extruder or kneading apparatus. Moreover, part of the other components may be kneaded with said components of the composition for kneading using an extruder or kneading apparatus so as to produce an intermediate raw material of the curable organopolysiloxane composition, and the remainder of the other components may be blended with the intermediate raw material. Details of these components will be described in later parts.
  • the production method of the present invention has a step of using an extruder or kneading apparatus to knead a composition for kneading that includes said curable organopolysiloxane, and the filler, and preferably, further includes the surface treatment agent.
  • This step enables uniform and higher filling content of the filler in the curable organopolysiloxane composition and simultaneously performing surface treatment of the filler due to the curable organopolysiloxane and the surface treatment agent.
  • This step is thus extremely useful as a production step for intermediate raw material for a curable organopolysiloxane composition for transducers.
  • This intermediate raw material is termed a "master batch”, "Silicone Elastomer Base” or “silicone rubber compound” (hereafter, the “Master batch etc.”).
  • This intermediate raw material is advantageous for the production of a curable organopolysiloxane composition for transducers due to advantages such as the ability to use a desired blending apparatus for kneading at a desired concentration with other raw materials such as other curable organopolysiloxane raw materials, fillers, or the like, ease of designing composition of the product, and excellent production efficiency. Furthermore, due to high filling content of the filler, the curable organopolysiloxane composition becomes highly viscous.
  • the filler content in the intermediate raw material obtained by kneading, in the total intermediate raw material is greater than or equal to 30 mass%, is greater than or equal to 50 mass%, is greater than or equal to 60 mass%, is greater than or equal to 70 mass%, is greater than or equal to 75 mass%, or is greater than or equal to 80 mass%.
  • a mechanical means that is at least one type selected from twin screw extruders, two shaft kneading apparatuses, and single screw blade type extruders, it is relatively easy to obtain the Mater Batch etc. that has a filler content of at least 80 mass% in the total intermediate raw material.
  • the intermediate raw material loaded with filler at high concentration has excellent handling and processability due to low viscosity in comparison to use of the filler alone, it is possible to improve production efficiency, and it is possible to blend other components for a desired composition. It is thus easy to design the compositional formulation of the curable organopolysiloxane composition for transducers. Moreover, as a result of uniform dispersion of the filler at high shear force, dispersibility of the finally obtained filler in the curable
  • organopolysiloxane composition for transducers is improved, and there is resistance to the occurrence of defects even when the composition is molded and cured as a film. It thus becomes possible to form a thin layer type component for transducers, and mechanical characteristics and electrical characteristics are improved.
  • the intermediate raw material may be an intermediate raw material having a high content of high dielectric filler or high electrical conductivity filler.
  • the intermediate raw material is obtained by a step using at least one type of mechanical means selected from twin screw extruders, twin screw kneading apparatuses, and single screw blade type extruders such that the filler content in the composition obtained by kneading of the curable organopolysiloxane, the high dielectric filler or high electrical conductivity filler, and at least one type of surface treatment agent is greater than or equal to 30 mass%, is greater than or equal to 50 mass%, is greater than or equal to 60 mass%, is greater than or equal to 70 mass%, is greater than or equal to 75 mass%, or is greater than or equal to 80 mass% of the total composition.
  • the intermediate raw material that has a filler content of greater than or equal to 70 mass%, greater than or equal to 75 mass%, or greater than or equal to 80 mass% of total mass may be blended by a desired mechanical means with other raw materials used in the curable organopolysiloxane composition, e.g. other curable organopolysiloxanes, vulcanizing agents, curing catalysts, or other ingredients. It is thus possible to readily obtain a curable
  • organopolysiloxane composition for transducers in which the filler and other ingredients are dispersed uniformly.
  • the production method of the present invention is characterized by comprising a step of using an extruder or kneading apparatus to knead the composition for kneading including said each component.
  • the extruder or kneading apparatus is exemplified by single screw extruders, twin screw extruders, multi-screw extruders, single screw blade type extruders, twin screw kneading apparatuses, continuous kneading apparatuses, batch-type kneading apparatuses, Banbury mixers (hermetically sealed type mixers), Henschel mixers, double roll mills, triple roll mills, continuous type two roll mills, continuous type triple roll mills, batch type roll mills, pressurized kneaders, change can type mixers, planetary type mixers, continuous ball mills, conical screw mixers, ribbon blenders, double arm or sigma blade mixers, dental mixers, or the like, or combinations of such apparatuses
  • an extruder or kneading apparatus in order to improve dispersibility of the filler, an extruder or kneading apparatus may be used that is capable of kneading while applying high shear force to the curable organopolysiloxane including the high viscosity filler.
  • This type of extruder or kneading apparatus is exemplified by at least one type of mechanical means selected from twin screw extruders, twin screw kneading apparatuses, and single screw blade type extruders.
  • kneading may be performed by premixing the filler and curable organopolysiloxane using an extruder, kneading apparatus, blender, or the like that imparts relatively low shear force, combined with an extruder or kneading apparatus thereafter that imparts high shear force.
  • the extruder, kneading apparatus, or blender for imparting relatively low shear force is exemplified by a Henschel mixer, change can mixer, planetary type mixer, conical screw mixer, ribbon blender, double arm or sigma blade mixer, dental mixer, or the like.
  • the aforementioned extruder or kneading apparatus may be exemplified as the extruder or kneading apparatus for imparting high shear force.
  • the kneading of the filler and the curable organopolysiloxane may be performed using a kneading apparatus or extruder by further addition of the filler and/or curable
  • organopolysiloxane after the above-described preparatory blending. Moreover, after kneading of the filler and the curable organopolysiloxane using the kneading apparatus or extruder, the filler and/or curable organopolysiloxane may be further added, and then kneading may be performed using a blending or kneading apparatus or extruder.
  • the concentration of filler in the composition obtained by kneading the composition of the filler and curable organopolysiloxane together using the extruder or kneading apparatus in the kneading by the extruder or kneading apparatus may designed as desired so as to become (relative to the total composition) greater than or equal to 30 mass%, greater than or equal to 50 mass%, greater than or equal to 60 mass%, greater than or equal to 70 mass%, greater than or equal to 75 mass%, or greater than or equal to 80 mass%; and by use in combination with a suitable surface treatment agent, it is possible to even knead at an extremely high filler concentration resulting in 98 mass% filler content.
  • the concentration of the filler relative to 100 parts by mass of the curable organopolysiloxane may be in the range of 1 to 5,000 parts by mass.
  • the lower limit of this filler concentration may be 5 parts by mass, 10 parts by mass, 25 parts by mass, 50 parts by mass, or 100 parts by mass.
  • the upper limit of this filler concentration may be 5,000 parts by mass, 4,000 parts by mass, 3,000 parts by mass, 2,000 parts by mass, or 1 ,500 parts by mass, 1 ,000 parts by mass, or 750 parts by mass.
  • the filler concentration may be selected appropriately according to the desired filler concentration or according to dielectric characteristics and mechanical strength. From the standpoints of industrial equipment and production efficiency, the concentration of the filler is generally selected in the range of 100 to 2,000 parts by mass.
  • this temperature may be set in the range of 40 °C to 200 °C, 80 °C to 190°C, or 100°C to 180°C.
  • a residence time of the treatment in a continuous process using a twin screw extruder or the like may be set to from about 30 seconds to about 5 minutes. The temperature conditions or the like during such continuous processing may be adjusted appropriately by setting temperature of the jacket of the extruder or the like.
  • kneading by a twin screw extruder or twin screw kneading apparatus is particularly preferably used.
  • FIG. 5 An example of a twin screw extruder is shown in FIG. 5.
  • this twin screw extruder 510 is equipped with rotatable twin screws 52 connected to a drive device 53, and the cylinder 51 has an opening (feed port 51 a) for feeding material into the cylinder 51 . Due to rotational driving of the twin screws 52, the material fed into the cylinder 51 from the first feed port 51 a is sent in the direction from left to right as viewed in the figure, and this material is discharged to the exterior of the cylinder 51 from a discharge port 51 b arranged at the tip of the cylinder 51 opposite to the tip where the feed port 51 a is arranged.
  • FIG. 5 is sometimes described hereinafter as the upstream side, and the rightward direction of FIG. 5 is sometimes described hereinafter as the downstream side.
  • a single feed port may be used as the cylinder 51 feed port, or alternatively, other feed ports may be provided in addition to the first feed port 51 a.
  • control of heating and cooling is possible to obtain a desired temperature at a desired location by equipping the cylinder 51 with a heating/cooling jacket and temperature sensors (omitted from the figure).
  • the rotation of the screws may be in the same direction or in mutually opposite directions.
  • first kneading disks 52a, second kneading disks 52b, and third kneading disks 52c are arranged, in order, along the twin screws 52 from the feed port
  • kneading disks are used for good kneading of the material within the cylinder 51. Material transported from the upstream direction is retained at the upstream side of each of the kneading disks, and due to rotation of the kneading disks, it is possible for the material to undergo kneading due to high compression and shear force. No particular limitation is placed on the cross-sectional shape of this type of kneading disk.
  • the utilized kneading disk may have various types of shapes as exemplified by elliptical, approximately elliptical, triangular, approximately triangular, rectangular, approximately rectangular, cross shaped, approximately cross shaped, or the like.
  • organopolysiloxane and filler may be each fed with raw materials to the twin screw extruder or twin screw kneading apparatus during pre-blending.
  • the components other than the curable organopolysiloxane and filler may be fed to the twin screw extruder or twin screw kneading apparatus without pre-blending.
  • a feeder 54 is disposed above the first feed port 51 a, and filler and curable organopolysiloxane for kneading may be fed to the feed port 51 a.
  • just the curable organopolysiloxane may be fed from the first feed port 51 a, and just the filler may be fed from the second feed port.
  • the pre-blended mixture of filler and curable organopolysiloxane may be fed from the first feed port 51 a, and just the filler may be fed from the second feed port.
  • organopolysiloxane may be fed from the first feed port 51 a, and just the curable
  • organopolysiloxane may be fed from the second feed port.
  • this method is sometimes referred to as the polymer cutback method.
  • an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by (i) feeding the organohydrogenpolysiloxane (i.e. curable organopolysiloxane) and filler into the cylinder 51 through the feed port 51 a, for example.
  • an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by (ii) feeding the organopolysiloxane having at least two alkenyl groups in a molecule (i.e.
  • an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by (iii) feeding the organohydrogenpolysiloxane, organopolysiloxane having at least two alkenyl groups in a molecule, and filler into the cylinder 51 through the feed port 51 a.
  • organopolysiloxane composition for transducers may be prepared by feeding the
  • diorganopolysiloxanes that are liquid at room temperature and having molecular terminals capped by silanol groups or silicon-bonded hydrolyzable groups, or partially hydrolyzed condensates of organosilanes having silicon-bonded hydrolyzable groups, and filler through the feed port 51 a into the cylinder 51 , for example.
  • an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by feeding the component organopolysiloxane raw rubber and filler through the feed port 51 a into the cylinder 51 , for example.
  • an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by feeding said each curable organopolysiloxane from the first feed port 51 a into the cylinder 51 , and feeding the filler into the cylinder 51 through the second feed port, for example.
  • an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by feeding said each curable organopolysiloxane and the filler into the cylinder 51 through the first feed port 51 a, and further feeding said each curable
  • organopolysiloxane into the cylinder 51 through the second feed port (polymer cutback method).
  • the cylinder 51 may firstly be set to a certain temperature, and the drive device 53 is operated to rotate the twin screws 52. Furthermore, temperature of the cylinder 51 may vary according to location in the cylinder 51 , or alternatively, the entire cylinder 51 may be set to a fixed temperature.
  • each of the desired and selected types of pre-mixed curable organopolysiloxane and filler are placed in the feeder 54, and the curable organopolysiloxane and filler are fed into the cylinder 51 through the feed port 51 a.
  • the curable organopolysiloxane and filler Due to rotation and driving of the twin screws 52, the curable organopolysiloxane and filler are sent from left to right as viewed in the figure, and the curable organopolysiloxane and filler are kneaded by the inter-meshing of the twin screws 52 and the kneading effect of the kneading disks.
  • the kneading disks were arranged at three locations within the cylinder 51 . However, as may be required, additional kneading disks may be provided.
  • the filler and curable organopolysiloxane kneaded in this manner are discharged from the discharge port 51 b, and the curable organopolysiloxane composition for transducers or an intermediate raw material thereof may be obtained.
  • the curable organopolysiloxane composition for transducers or an intermediate raw material thereof may be obtained.
  • the extruder or kneading apparatus is preferably a twin screw extruder in which the free volume as hereinafter defined of the extruder or kneading apparatus is set to greater than or equal to 5,000 (L/hr), greater than or equal to 7,500 (L/hr), or greater than or equal to 10,000 (L/hr).
  • the free volume as hereinafter defined of the extruder or kneading apparatus is set to greater than or equal to 5,000 (L/hr), greater than or equal to 7,500 (L/hr), or greater than or equal to 10,000 (L/hr).
  • a suitable apparatus is an apparatus having a free volume of 10,000 to 30,000 (L/hr), as exemplified by a twin screw kneading apparatus such as a model 4BKRC or TEM-100 kneading apparatus.
  • the L/D ratio is preferably less than or equal to 50, or less than or equal to 20.
  • the production method of the member for transducers of the present invention has a step of curing the curable organopolysiloxane composition for transducer use. According to this method of production of the member for transducers, it is possible to produce a member for transducers in which the filler is well dispersed in the silicone elastomer (i.e. cured product of the curable organopolysiloxane), and thus it is possible to produce a member for transducers that has good electrical characteristics or mechanical characteristics.
  • each of the curing agents i.e. crosslinking agents, catalysts, or polymerization initiation agents
  • solvents and/or additives or the like are added and blended, to prepare the curable organopolysiloxane composition.
  • a solvent may be used for dilution of the curable organopolysiloxane composition.
  • This type of solvent is preferably exemplified by water, and organic solvents such as lower alcohols such as ethyl alcohol, butyl alcohol, isopropyl alcohol, or the like; ketones such as methyl isobutyl ketone, methyl ethyl ketone, acetone, or the like; ethers such as dioxane, diethylene glycol dimethyl ether, tetrahydrofuran, methyl-t-butyl ether, or the like; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether acetate, or the like.
  • methyl acetate, ethyl acetate, butyl acetate, pentyl acetate, ethyl lactate, diethyl succinate, diethyl adipate, dibutyl phthalate, dioctyl phthalate, and similar esters such as dibasic acid esters and the like; chlorinated and fluorinated hydrocarbons, trichloroethane, and similar halogenated hydrocarbons such as chlorinated hydrocarbons, fluorinated hydrocarbons, and the like; toluene, xylene, hexane, and similar hydrocarbons; and the like can be used.
  • the curing system As far as obtained by said production method, no particular limitation is placed on the curing system, and any curing reaction system may be employed for the curable organopolysiloxane composition of the present invention.
  • the curable organopolysiloxane composition of the present invention is cured by condensation curing system or addition curing system.
  • peroxide curing radical-induced curing
  • high energy ray ex. ultraviolet ray
  • the method of forming the cured body by forming a cross-linking structure in the solution state and drying with solvent removal may be employed.
  • the curable organopolysiloxane composition comprises reactive organopolysiloxane and the composition satisfys satisfies the conditions of [Characteristic 1 ] through [Characteristic 3], and the optional [Characteristic 4] and [Characteristic 5].
  • the curable organopolysiloxane composition of the present invention comprises the reactive organopolysiloxane represented by general formula M a M R b D c D R d T e T R f Q g .
  • M represents a triorganosiloxy group
  • D represents a diorganosiloxy group
  • T represents a monoorganosiloxy group
  • Q is a siloxy unit representing Si0 42 .
  • T R are siloxy units in which one of the R substituting groups of the siloxy units represented by M,
  • D, and T are substituting groups capable of curing reaction in a condensation reaction, addition reaction, peroxide reaction, or photoreaction; although this group is preferably a group capable of addition reaction.
  • the substituting group capable of curing reaction is preferably a group active in a hydrosilylation reaction, i.e. a silicon atom-bonded hydrogen atom or an aliphatic unsaturated bond-containing group (such as an alkenyl group of 2 to 20 carbon atoms, or the like).
  • the non-R substituting groups of the aforementioned reactive organopolysiloxane are preferably groups that do not participate in the addition reaction or are highly dielectric functional groups, as exemplified by alkyl groups such as the methyl group, ethyl group, propyl group, butyl group, hexyl group, or the like; aryl groups such as the phenyl group, o-tolyl group, p-tolyl group, naphthyl group, halogenated phenyl group, or the like; alkoxy groups; or the like.
  • the methyl group is preferred from the standpoint of economics.
  • reactive organopolysiloxane examples include trimethylsiloxy group-doubly molecular chain terminated dimethylsiloxane-methylhydrogensiloxane copolymers, trimethylsiloxy group-doubly molecular chain terminated
  • dimethylsiloxane-methylvinylsiloxane copolymers dimethylhydrogensiloxy group-doubly molecular chain terminated dimethylsiloxane-methylhydrogensiloxane copolymers,
  • methylsiloxane-dimethylsiloxane-methylvinylsiloxane copolymers dimethylhydrogen functionalized MQ resins, dimethylvinyl functionalized MQ resins, or the like.
  • Number average molecular weight (Mw) of the aforementioned reactive organopolysiloxane is in the range of 300 to 10,000.
  • Viscosity measured under 10 (s ⁇ 1 ) shear rate conditions at 25 using a rheometer equipped with a cone plate of 20 mm diameter is preferably in the range of 1 to 10,000 mPa-s, and particularly preferably is in the range of 5 to 5,000 mPa-s.
  • the proportion of the aforementioned reactive organopolysiloxane (formed such that the value of (a + c)/(b + d + e + f + g) is less than 3) relative to the entire amount of the siloxane component in the curable organopolysiloxane composition is less than 0.1 % by weight, the number of crosslink points in the polysiloxane component is excessively low, and thus mechanical strength and dielectric breakdown strength after the curing reaction are insufficient. Conversely, a proportion in excess of 25% by weight is unsuitable since the number of crosslink points is excessive, and thus post-curing elasticity is high, and break elongation is low. This proportion is preferably less than or equal to 10% by weight.
  • curing reaction-capable group means a group that is capable of use as a group in a condensation reaction, addition reaction, peroxide reaction, or photoreaction. However, for reasons similar to those described above, this group is preferably capable of an addition reaction.
  • the group is preferably active in a hydrosilylation reaction, i.e. is a group containing a silicon atom-bonded hydrogen atom or aliphatic unsaturated bond-containing group (such as an alkenyl group of 2 to 20 carbon atoms, or the like).
  • reactive organopolysiloxane examples include dimethylhydrogensiloxy group-doubly molecular chain terminated polydimethylsiloxane and dimethylvinylsiloxy group-doubly molecular chain terminated polydimethylsiloxane.
  • methyl groups of such polymers it is possible for part of the methyl groups of such polymers to be replaced by an ethyl group, propyl group, butyl group, hexyl group, or phenyl group.
  • Number average molecular weight (Mw) of the reactive organopolysiloxane having curing reaction-capable groups only at both molecular chain terminals is in the range of 300 to 100,000.
  • this viscosity is preferably in the range of 1 to 100,000 mPa-s, and particularly preferably is in the range of 5 to 10,000 mPa-s.
  • a proportion of this reactive organopolysiloxane having curing reaction-capable groups only at both molecular chain terminals relative to the total siloxane component in the curable organopolysiloxane composition less than 75% by weight is inappropriate in that high elongation at break may not be achieved. Conversely, when this value exceeds 99.9% by weight, the proportion of the molecule involved in the crosslinking reaction becomes low, and post-curing mechanical strength and dielectric breakdown strength are insufficient. Thus a proportion in excess of 99.9% by weight is inappropriate.
  • Average molecular weight between these two groups capable of the curing reaction is less than
  • organopolysiloxane (L) which is a reactive organopolysiloxane having at least two curing reaction-capable groups within a single molecule and is used in the present invention.
  • These reactive organopolysiloxanes are contained in the molecule as a short chain non-reactive polymer part and a long chain non-reactive polymer part, respectively.
  • the molecular weight between these two groups capable of the crosslinking reaction in the case of a chain type organopolysiloxane that has reactive functional groups only at both terminals of the molecular chain, is defined as the molecular weight of the non-reactive polysiloxane part (not including the siloxy units at both terminals). In the case of molecular weight between multiple crosslinking reaction-capable groups, this is the molecular weight of the longest part.
  • component (S) and component (L) are used together in a range of 1 :99 to 40:60 as reactive organopolysiloxane raw materials, it is possible to introduce parts of different chain lengths in the silicone chain part constituting the silicone elastomer obtained by the curing reaction. By this means, it is possible to reduce permanent strain of the obtained silicone polymer, and it is possible to decrease the mechanical energy conversion loss.
  • the silicone elastomer of the present invention is used in the dielectric layer of a transducer, this combined use of the component (S) and component (L) has the practical advantage of increasing the energy conversion efficiency.
  • the group is preferably a group active in a hydrosilylation reaction, i.e. a silicon atom-bonded hydrogen atom or an aliphatic unsaturated bond-containing group (such as an alkenyl group of 2 to 20 carbon atoms, or the like).
  • reactive organopolysiloxanes (S) and (L) are the examples cited as the aforementioned reactive organopolysiloxanes represented by M a M R b D c D R d T e T R f Q g and the examples cited as the aforementioned reactive organopolysiloxanes having curing reaction-capable groups only at both molecular chain terminals.
  • part of the methyl groups may be replaced by an ethyl group, propyl group, butyl group, hexyl group, or phenyl group.
  • a value of the blend ratio (weight content ratio) S:L of the component (S) to the below described component (L) that departs from the range of 1 :99 to 40:60 is inappropriate due to non-ability to satisfy at least one type of characteristic of the obtained cured article, these characteristics including high break elongation, high mechanical strength, high dielectric breakdown strength, and low elastic modulus.
  • the blend ratio (molar ratio) of the silicon atom-bonded hydrogen atoms to silicon atom-bonded unsaturated hydrocarbon groups (Vi) in the polysiloxane is preferably in the range of 0.5 to 3.0.
  • the curable organopolysiloxane composition for transducers of the present invention comprises the below described (A) and (B).
  • the number of crosslink points per unit weight after the curing reaction of the reactive polysiloxane is defined by the below listed calculation formulae based on the number average molecular weights of each component of the (A) component and (B) component, the values in the below described general formulae of a, to g, and a j to and the contents of each of the components in the composition.
  • This number of crosslink points per unit weight after the curing reaction of the reactive polysiloxane is preferably in the range of 0.5 to 20 ⁇ /g, and further preferably is in the range of 0.5 to 10 ⁇ /g.
  • An organohydrogenpolysiloxane comprising one or multiple components, represented by general formula M a iM H biD C iD H dTeiT H fi Q g i, having a number average molecular weight (Mw) in the range of 300 to 15,000, and having at least 2 silicon-bonded hydrogen atoms on average in a single molecule
  • An organopolysiloxane comprising one or multiple components, represented by general formula M a jM Vl biD ci D Vl djTejT Vl fjQgj, having a number average molecular weight (Mw) in the range of 300 to 100,000, and having at least 2 alkenyl groups on average in a single molecule
  • M represents R 3 Si0 1 2
  • D represents R 2 Si0 2/2
  • T represents RSi0 3/2
  • Q is the siloxane unit represented by Si0 4/2
  • R is a monovalent organic group not having an aliphatic carbon-carbon double bond
  • M H , D H , and T H are siloxane units in which one of the R groups of the siloxane units represented by M, D, and T, respectively, is replaced by a silicon atom-bonded hydrogen atom
  • are siloxane units in which one of the R groups
  • the aforementioned number of crosslink points per unit weight is calculated using the below listed values of the indices defined by each of the formulae for (i) the index of probability of inter terminal group reaction, (ii) the index of number of crosslink points of the reaction composition,
  • the index of number of crosslink points of the reaction composition is represented by the below formula based on the aforementioned index of probability of inter terminal group reaction).
  • the index of raw material mole count in the reaction composition is represented by the following formula.
  • a, a w / ⁇
  • ft represents the blending amount (an amount by weight) of the j-th component of the component (B)
  • M wi represents number average molecular weight of the i-th component of the component (A)
  • M wj represents number average molecular weight of the j-th component of the component (B).
  • the molecular weight between crosslink points of the reactive polysiloxane after the curing reaction is defined by the below formulae based on the number average molecular weight of each of the components of the (A) component and (B) component, the values of a, to g, and 3 ⁇ 4 to g j of the below general formulae, and the concentrations of each component in the composition, where this molecular weight between crosslink points of the reactive polysiloxane after the curing reaction is preferably in the range of 100,000 to 2,000,000, and further preferably is in the range of 200,000 to 2,000,000:
  • (A) is an organohydrogenpolysiloxane comprising one or multiple components, represented by general formula M ai M H biD C iD H d iTeiT H 1 iQgi, having a number average molecular weight (Mw) in the range of 300 to 15,000, and having at least 2 silicon-bonded hydrogen atoms on average in a single molecule.
  • Mw number average molecular weight
  • (B) is an organopolysiloxane comprising one or multiple components, represented by general formula having a number average molecular weight (Mw) in the range of 300 to 100,000, and having at least 2 alkenyl groups on average in a single molecule.
  • Mw number average molecular weight
  • (C) is a catalyst for addition reaction between the aforementioned component (A) and component (B).
  • R is a monovalent organic group not having an aliphatic carbon-carbon double bond;
  • M H , D H , and T H are siloxane units in which one of the R groups of the siloxane units represented by M, D, and T, respectively, is replaced by a silicon atom-bonded hydrogen atom;
  • are siloxane units in which one of the R groups of the siloxane units represented by M, D, and T, respectively, is replaced by an alkenyl group of 2 to 20 carbon atoms;
  • a is an average number per single molecule;
  • b is an average number per single molecule;
  • c is an average number per single molecule;
  • d is an average number per single molecule;
  • e is an average
  • the aforementioned molecular weight between crosslink points is based on the index values calculated based on the below represented calculation formulae for (i) the index of probability of inter terminal group reaction, ( ⁇ ') the index of organosiloxane chain count of the reaction composition, (iii) the index of raw material mole count in the reaction composition, and (iv) the index of molecular weight of the reaction composition:
  • the index of raw material mole count in the reaction composition is represented by the following formula.
  • a, aTM/ ⁇
  • ft represents the blending amount (an amount by weight) of the j-th component of the component (B)
  • M wi represents number average molecular weight of the i-th component of the component (A)
  • M Wj represents number average molecular weight of the j-th component of the component (B).
  • the aforementioned number average molecular weight (Mw) is a value determined by measurement by nuclear magnetic resonance (NMR).
  • the curable organopolysiloxane composition for transducers of the present invention comprises a curing agent (C) as a necessary ingredient.
  • the component (C) is preferably a generally known hydrosilylation reaction catalyst. No particular limitation is placed on the component (C) used in the present invention, as long as the component (C) is a substance capable of promoting the hydrosilylation reaction.
  • This component (C) is exemplified by platinum based catalysts, rhodium based catalysts, and palladium based catalysts. Due to high catalyst activity, particularly platinum family element catalysts and platinum family element compound catalysts are cited as the component (C).
  • platinum based catalysts are exemplified by platinum fine powder, platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid; olefin-platinum complexes, platinum-carbonyl complexes such as platinum bis-acetoacetate), platinum bis(acetylacetate), or the like; chloroplatinic acid-alkenyl siloxane complexes such as chloroplatinic acid-divinyltetramethyldisiloxane complex, chloroplatinic
  • platinum-alkenylsiloxane complexes such as platinum-divinyltetramethyldisiloxane complex
  • platinum-alkenylsiloxane complexes and particularly platinum
  • platinum-alkenylsiloxane complexes may be dissolved in an organosiloxane oligomer such as alkenylsiloxane oligomers of 1 ,3— divinyl— 1 ,1 ,3,3-tetramethyldisiloxane,
  • the utilized amount of the component (C) may be any amount capable of promoting the addition reaction of the polysiloxane component of the present composition, without particular limitation.
  • the concentration of a platinum family metal element contained in the component (C) is normally in the range of 0.01 to 500 ppm, preferably is in the range of 0.1 to 100 ppm, and further preferably is in the range of 0.1 to 50 ppm.
  • the curable organopolysiloxane composition for transducers of the present invention is characterized as containing, as necessary ingredients, the curable organopolysiloxane composition having the aforementioned characteristics, a curing agent, and (D) dielectric particles having a specific dielectric constant at 1 kHz of greater than or equal to 10 at room temperature.
  • the dielectric inorganic fine particles may be selected from among metal oxides (D1 ) represented by the below listed Formula (D1 ) (sometimes abbreviated hereinafter as the "metal oxide (D1 )”):
  • M a is a family 2 metal of the periodic table
  • M b is a family 4 metal of the periodic table
  • na is a number ranging from 0.9 to 1.1 ;
  • nb is a number ranging from 0.9 to 1.1 ;
  • nc is a number ranging from 2.8 to 3.2).
  • Preferred examples of the family 2 periodic table metal M a in the metal oxide (D1 ) include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Titanium (Ti) is cited as a preferred example of a family 4 periodic table metal M b .
  • M a and M b may each be a single element, or may be 2 or more elements.
  • metal oxide (D1 ) examples include barium titanate, calcium titanate, and strontium titanate.
  • the dielectric inorganic fine particles may be selected from among metal oxides (hereinafter, can be referred to as "metal oxide (D2)”) represented by:
  • M a is a family 2 metal of the periodic table
  • M b is a family 5 metal of the periodic table
  • na is a number ranging from 0.9 to 1.1 ;
  • nb' is a number ranging from 0.9 to 1 .1 ;
  • nc is a number ranging from 2.8 to 3.2).
  • Preferred examples of the family 2 periodic table metal M a in the metal oxide (D2) include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).
  • Preferred examples of the family 5 periodic table metal element M b include tin (Sn), antimony (Sb), zirconium (Zr), and indium (In).
  • M a and M b may each be a single type of element, or may be 2 or more elements.
  • metal oxide (D2) examples include magnesium stannate, calcium stannate, strontium stannate, barium stannate, magnesium antimonate, calcium antimonate, strontium antimonate, barium antimonate, magnesium zirconate, calcium zirconate, strontium zirconate, barium zirconate, magnesium indate, calcium indate, strontium indate, barium indate, or the like.
  • the dielectric inorganic fine particles D
  • the other metal elements are exemplified by La (lanthanum), Bi (bismuth), Nd (neodymium), Pr (praseodymium), or the like.
  • (D) include one or more types of inorganic fine particles selected from the group consisting of titanium oxide, barium titanate, strontium titanate, lead titanate zirconate, and barium titanate, and composite metal oxides in which the barium and titanium positions of barium titanate are partially replaced by an alkaline earth metal, such as calcium or strontium; zirconium ; or rare earth metal, such as yttrium, neodymium, samarium, or dysprosium. Titanium oxide, barium titanate, strontium titanate, and composite metal oxide in which the barium positions of barium titanate and barium zirconate are partially replaced by calcium are more preferred, and titanium oxide and barium titanate are most preferred.
  • particle diameter of the inorganic fine particles and if the spherical fine particles are measured by the laser diffraction method, for example, the volume average particle diameter may be in the range of 0.01 to 1 .0 ⁇ , for example. From the standpoints of molding-processing ability and film forming ability, the average particle diameter is preferably in the range of 0.1 to 5 ⁇ .
  • the inorganic fine particles are anisotropic fine particles in which the morphology is tabular, needle-like, fibrous, or the like, although no limitation is placed on the aspect ratio of such fine particles, the aspect ratio may normally be greater than or equal to 5.
  • the dielectric inorganic fine particles may be mono-dispersed, or alternatively, it is possible to produce a distribution in the particle diameters so as to improve mechanical strength by filling at higher density by lowering the void fraction between fine particles.
  • the ratio (D 90 /D 10 ) of the particle diameter at 90% cumulative area (D 90 ) over the particle diameter at 10% cumulative area (D 10 ) of the cumulative particle diameter distribution curve measured by the laser light diffraction method is preferably greater than or equal to 2.
  • particle diameter distribution shape (relationship between particle diameter and particle concentration)
  • particle diameter distribution shape it is possible to have a so-called plateau shaped distribution, or a particle diameter distribution that is multi-modal, i.e. bimodal (i.e. Having two hill-shaped distributions), tri-modal, or the like.
  • particle size distributions such as those described above for the dielectric inorganic fine particles used in the present invention
  • methods may be adopted, for example, such as combined use of two or more types of fine particles having different average diameters or particle size distributions, blending of particles of particle diameter fractions obtained by sieving or the like to produce a desired particle size distribution, or the like.
  • dielectric inorganic fine particles may be treated using various types of the below described surface treatment agents.
  • the blended amount (loading fraction) of the dielectric inorganic fine particles in the curable organopolysiloxane composition for transducers of the present invention may be greater than or equal to 10%, preferably is greater than or equal to 15%, and further preferably is greater than or equal to 20%. Moreover, this blended amount relative to the total volume of the composition is preferably less than or equal to 80%, and further preferably is less than or equal to 70%.
  • a composition for transducers of the present invention, comprises as necessary ingredients: (A1 ) at least one type of organohydrogenpolysiloxane having silicon atom-bonded hydrogen atoms at both molecular terminals and having a hydrogen atom weight content of 0.01 to 1 .0% by weight, (A2) at least one type of organohydrogenpolysiloxane having at least 3 silicon atom-bonded hydrogen atoms in a single molecule and having a hydrogen atom weight content of 0.03 to 2.0% by weight, (B) at least one type of organopolysiloxane having at least 2 alkenyl groups in a single molecule and having an alkenyl group weight content of 0.05 to 0.5% by weight, (C1 ) a hydrosilylation reaction catalyst, and (D) dielectric inorganic fine particles having a specific dielectric constant at 1 kHz of greater than or equal to 10 at room temperature.
  • (A1 ) is preferably a dimethylhydrogensiloxy group-doubly molecular chain terminated polydimethylsiloxane.
  • Preferred examples of (A2) include trimethylsiloxy group-doubly molecular chain terminated dimethylsiloxane-methylhydrogensiloxane copolymers and dimethylhydrogensiloxy group-doubly molecular chain terminated
  • the (B) component is exemplified by dimethylvinylsiloxy group-doubly molecular chain terminated
  • part of the methyl groups of the polymers may be replaced by an ethyl group, propyl group, butyl group, hexyl group, or phenyl group.
  • the curable organopolysiloxane composition of the present invention is a curable
  • organopolysiloxane composition used for transducers and the curable organopolysiloxane composition of the present invention may be further provided with the below described characteristics.
  • the curable organopolysiloxane composition of the present invention may further comprise one or more types of inorganic particles (E) selected from the group consisting of electrically conductive inorganic particles, insulating-inorganic particles, and reinforcing-inorganic particles.
  • E inorganic particles
  • electrically conductive inorganic particles include: electrically conductive carbon such as electrically conductive carbon black, graphite, monolayer carbon nanotubes, double layer carbon nanotubes, multilayer carbon nanotubes, fullerenes, fullerene-encapsulated metals, carbon nanofibers, gas phase-grown mono-length carbon (VGCF), carbon micro-coils, or the like; and metal powders such as platinum, gold, silver, copper, nickel, tin, zinc, iron, aluminum, or the like powders; as well coated pigments such as antimony-doped tin oxide, phosphorous-doped tin oxide, needle-shaped titanium oxide surface-treated using tin/antimony oxide, tin oxide, indium oxide, antimony oxide, zinc antimonate
  • the electrically conductive inorganic fine particles may be fibers such as glass fibers, silica alumina fibers, alumina fibers, carbon fibers, or the like, or needle-like reinforcing materials such as aluminum borate whiskers, potassium titanate whiskers, or the like; or an inorganic filler material such as glass beads, talc, mica, graphite, wollastonite, dolomite, or the like, that have been surface coated by an electrically conductive substance such as a metal or the like.
  • fibers such as glass fibers, silica alumina fibers, alumina fibers, carbon fibers, or the like, or needle-like reinforcing materials such as aluminum borate whiskers, potassium titanate whiskers, or the like
  • an inorganic filler material such as glass beads, talc, mica, graphite, wollastonite, dolomite, or the like, that have been surface coated by an electrically conductive substance such as a metal or the like.
  • the electrically conductive inorganic particles By blending the electrically conductive inorganic particles into the composition, it is possible to increase the specific dielectric constant of the polysiloxane cured article.
  • the blended amount of such electrically conductive inorganic particles relative to the curable organopolysiloxane composition is preferably in the range of 0.01 to 10% by weight, and further preferably is in the range of 0.05 to 5% by weight. When the blended amount departs from the aforementioned preferred range, the effect of blending is not obtained, or there may be a lowering of the dielectric breakdown strength of the cured article.
  • the insulating-inorganic particles utilized in the present invention may be any generally known insulating inorganic material. That is to say, particles of any inorganic material having a volume resistance value of 10 10 to 10 19 Ohm-cm may be used without restriction, and any morphology may be used, such as particulate, flake-like, and fibrous (including whiskers).
  • Preferred specific examples include spherical particle, tabular particles, and fibers of ceramics; particles of metal silicates such as alumina, mica and talc or the like; and quartz, glass, or the like.
  • Such insulating-inorganic particles may be surface-treated using the various types of below described surface treatment agents.
  • Such electrically conductive inorganic particles may be used as one type or as a combination of 2 or more types.
  • the insulating-inorganic particles By blending the insulating-inorganic particles into the composition, it becomes possible to increase the mechanical strength and dielectric breakdown strength of the polysiloxane cured article, and the specific dielectric constant may sometimes be observed to increase.
  • organopolysiloxane composition is preferably in the range of 0.1 to 20% by weight, and further preferably is in the range of 0.1 to 5% by weight.
  • insulating-inorganic particles deviates from the aforementioned preferred range, the effect of blending is not obtained, or there may be a lowering of the mechanical strength of the cured article.
  • the reinforcing-inorganic particles used in the present invention are exemplified by fumed silica, wet type silica, ground silica, calcium carbonate, diatomaceous earth, finely ground quartz, various types of non-alumina metal oxide powders, glass fibers, carbon fibers, or the like.
  • such reinforcing inorganic particle may be used after treatment using the below described various types of surface treatment agents.
  • the specific surface area is preferably greater than or equal to 50 m 2 /g and less than or equal to 300 m 2 /g from the standpoint of improvement of mechanical strength, fumed silica is particularly preferred.
  • the fumed silica is preferably surface-treated using the below described silica coupling agent.
  • the (A) curable organopolysiloxane composition is an addition-curable type organopolysiloxane composition
  • fumed silica surface-treated using silazane is not used as the reinforcing-inorganic particles.
  • These reinforcing-inorganic particles may be used as a single type, or may be used as a combination of 2 or more types.
  • the reinforcing-inorganic particles By blending the reinforcing-inorganic particles into the composition, it becomes possible to increase mechanical strength and dielectric breakdown strength of the polysiloxane cured article.
  • organopolysiloxane composition is preferably in the range of 0.1 to 30% by weight, and further preferably in the range of 0.1 to 10% by weight.
  • the blended amount deviates from the aforementioned preferred range, the effect of blending and the inorganic particles is not obtained or molding processability of the curable organopolysiloxane composition may decrease.
  • the curable organopolysiloxane composition of the present invention may further comprise thermally conductive inorganic particles.
  • the thermally conductive inorganic particles are exemplified by metal oxide particles such as magnesium oxide, zinc oxide, nickel oxide, vanadium oxide, copper oxide, iron oxide, silver oxide, or the like; and inorganic compound particles such as aluminum nitride, boron nitride, silicon carbide, silicon nitride, boron carbide, titanium carbide, diamond, diamond-like carbon, or the like. Zinc oxide, boron nitride, silicon carbide, and silicon nitride are preferred.
  • the blended amount of these reinforcing-inorganic particles is preferably in the range of 0.1 to 30% by weight.
  • the aforementioned dielectric inorganic fine particles (D) and at least one type of the inorganic particles (E) used in the curable organopolysiloxane composition of the present invention may undergo surface treatment by use of at least one type of surface treatment agent.
  • surface treatment is exemplified by hydrophilization treatment and hydrophobizing treatment. Hydrophobization treatment is preferred.
  • inorganic particles are used that have undergone hydrophobizing treatment, it is possible to increase the degree of loading of the inorganic particles in the organopolysiloxane composition. Moreover, increase of viscosity of the composition is suppressed, and molding processability is improved.
  • the aforementioned surface treatment may be performed by treatment (or coating treatment) of the inorganic particles using a surface treatment agent.
  • the surface treatment agent used for hydrophobizing is exemplified by at least one type of surface treatment agent selected from the group consisting of organic titanium compounds, organic silicon compounds, organic zirconium compounds, organic aluminum compounds, and organic phosphorous compounds.
  • the surface treatment agent may be used as a single type or may be used as a combination of 2 or more types.
  • the organic titanium compound is exemplified by coupling agents such as alkoxy titanium, titanium chelates, titanium acrylates, or the like.
  • Preferred coupling agents among such compounds are exemplified by alkoxy titanium compounds such as tetraisopropyl titanate or the like, and titanium chelates such as tetraisopropyl bis(dioctylphosphate) titanate or the like.
  • the organic silicon compound is exemplified by low molecular weight organic silicon compounds such as silanes, silazanes, siloxanes, or the like; and organic silicon polymers or oligomers such as polysiloxanes, polycarbosiloxanes, or the like.
  • organic silicon compounds such as silanes, silazanes, siloxanes, or the like
  • organic silicon polymers or oligomers such as polysiloxanes, polycarbosiloxanes, or the like.
  • Preferred silanes are exemplified by so-called silane coupling agents.
  • silane coupling agents include alkyltrialkoxysilanes (such as methyltrimethoxysilane, vinyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, or the like), organic functional group-containing trialkoxysilane (such as glycidoxypropyltrimethoxysilane, epoxycyclohexylethyltrimethoxysilane, methacryloxypropyltrimethoxysilane, aminopropyltrimethoxysilane, or the like).
  • alkyltrialkoxysilanes such as methyltrimethoxysilane, vinyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, or the like
  • organic functional group-containing trialkoxysilane such as glycidoxypropyltrimethoxysilane, epoxycyclohexylethyl
  • Preferred siloxanes and polysiloxanes include hexamethyldisiloxane, 1 ,3-dihexyl-tetramethyldisiloxane, trialkoxysilyl single-terminated polydimethylsiloxane, trialkoxysilyl single-terminated dimethylvinyl single-terminated polydimethylsiloxane, trialkoxysilyl single terminated organic functional group single-terminated polydimethylsiloxane, trialkoxysilyl doubly terminated polydimethylsiloxane, organic functional group doubly-terminated polydimethylsiloxane, or the like.
  • the number n of siloxane bonds is preferably in the range of 2 to 150.
  • Preferred silazanes are exemplified by hexamethyldisilazane,
  • Preferred polycarbosiloxanes are exemplified by polymers that have Si-C-C-Si bonds in the polymer main chain.
  • the organic zirconium compound is exemplified by alkoxy zirconium compounds such as tetraisopropoxy zirconium or the like and zirconium chelates.
  • the organic aluminum compound is exemplified by alkoxy aluminum and aluminum chelates.
  • the organic phosphorous compound is exemplified by phosphite esters, phosphate esters, and phosphorous acid chelates.
  • organic silicon compounds are preferred.
  • silanes, siloxanes, and polysiloxanes are preferred.
  • polydimethylsiloxanes is most preferred.
  • the ratio of the surface treatment agent to the total amount of the aforementioned inorganic particles is preferably in the range of greater than or equal to 0.1 % by weight and less than or equal to 10% by weight, and this range is further preferably greater than or equal to 0.3% by weight and less than or equal to 5% by weight.
  • the treatment concentration is the ratio (weight ratio) of the fed inorganic particles to the fed treatment agent, and the excess treatment agent is preferably removed after treatment.
  • the curable organopolysiloxane composition of the present invention may further comprise an additive (F) for improvement of mold releasability or insulation breakdown characteristics.
  • the electrically active silicone elastomer sheet obtained by curing this polysiloxane composition as a thin sheet may be used with advantage as an electrically active film (dielectric layer or electrode layer) constituting a transducer.
  • the dielectric film may be damaged due to demolding.
  • the curable organopolysiloxane composition for transducers of the present invention has excellent demolding characteristics, and thus the curable organopolysiloxane composition is
  • This additive further improves these features of the curable organopolysiloxane composition of the present invention, and this additive may be used as a single type or as a combination of 2 or more types.
  • an additive for improvement of insulation breakdown characteristics is used for improvement of dielectric breakdown strength of the silicone elastomer sheet.
  • Demolding improvement additives capable of use are exemplified by carboxylic acid type demolding agents, ester type demolding agents, ether type demolding agents, ketone type demolding agents, alcohol type demolding agents, or the like. Such demolding agents may be used alone as a single type or may be used as a combination of 2 or more types. Moreover, although the aforementioned demolding agents do not contain silicon atoms, it is also possible to use a demolding agent that contains silicon atoms, or it is possible to use a mixture of such demolding agents.
  • the demolding agent that does not contain silicon atoms may be selected, for example, from the group consisting of saturated or unsaturated fatty carboxylic acids such as palmitic acid, stearic acid, or the like; alkali metal salts of such fatty carboxylic acids (such as sodium stearate, magnesium stearate, calcium stearate, or the like); esters of fatty carboxylic acids and alcohols (such as 2-ethylhexyl stearate, glycerin tristearate, pentaerythritol monostearate, or the like), aliphatic hydrocarbons (liquid paraffin, paraffin wax, or the like), ethers (distearyl ether or the like), ketones (distearyl ketone or the like), higher alcohols (2-hexadecyloctadecanol or the like), and mixtures of such compounds.
  • saturated or unsaturated fatty carboxylic acids such as palmitic acid, stearic acid,
  • the silicon atom-containing demolding agent is preferably a non-curable silicone type demolding agent.
  • silicone type demolding agents include non-organic modified silicone oils such as polydimethylsiloxane, polymethylphenylsiloxane, poly(dimethylsiloxane-methylphenylsiloxane) copolymers,
  • Such silicon atom-containing demolding agents may have any structure, such as linear, partially-branched linear, or ring shaped.
  • no particular limitation is placed on the viscosity of such silicon oils at 25 °C. This viscosity is preferably in the range of 10 to 100,000 mPa-s, and further preferably is in the range of 50 to 10,000 mPa-s.
  • this amount is preferably in the range of greater than or equal to 0.1% by weight and less than or equal to 30% by weight.
  • the insulation breakdown characteristic improvement agent is preferably an electrical insulation improvement agent.
  • the insulation breakdown characteristic improvement agent is exemplified by aluminum or magnesium hydroxides or salts, clay minerals, and mixtures of such.
  • the insulation breakdown characteristic improvement agent may be selected from the group consisting of aluminum silicate, aluminum sulfate, aluminum hydroxide, magnesium hydroxide, calcined clays, montmorillonite, hydrotalcite, talc, and mixtures of such agents.
  • this insulation improvement agent may be
  • this blended amount is preferably in the range of greater than or equal to 0.1% by weight and less than or equal to 30% by weight.
  • the curable organopolysiloxane composition of the present invention may comprise another organopolysiloxanes that differs from the aforementioned reactive organopolysiloxane that that has dielectric functional groups.
  • the curable organopolysiloxane composition of the present invention may further comprise a compound that has highly dielectric functional groups and at least one group in the molecule capable of reacting by condensation curing reaction, addition curing reaction, peroxide curing reaction, or photo-curing reaction.
  • This highly dielectric functional group is introduced to the obtained cured article (i.e. electrically active silicone elastomer) by the aforementioned curing reaction.
  • part or the entire aforementioned reactive organopolysiloxane may be a reactive organopolysiloxane further having a highly dielectric functional group.
  • an electrically active silicone elastomer obtained by curing the curable organopolysiloxane composition for transducers of the present invention is used for a dielectric layer
  • specific dielectric constant of the dielectric layer is preferably high, and highly dielectric functional groups may be introduced in order to improve the specific dielectric constant of the elastomer.
  • dielectric properties may be increased for the curable organopolysiloxane composition and cured electrically active silicone elastomer obtained by curing the curable organopolysiloxane composition, by a method such as adding to the curable organopolysiloxane composition a component for imparting high dielectric properties, a method of introducing a highly dielectric group to the organopolysiloxane component constituting the curable
  • organopolysiloxane composition or a combination of such methods.
  • the curable organopolysiloxane composition for transducers is formed from a curable organopolysiloxane composition that comprises an organic silicon compound that has a highly dielectric group.
  • this curable composition part or the entire reactive
  • organopolysiloxane contained in the curable composition is a reactive organopolysiloxane further having a highly dielectric functional group, and the specific dielectric constant of the electrically active silicone elastomer obtained by curing is increased.
  • an organic silicon compound having highly dielectric groups is added to the curable organopolysiloxane composition, and the mixture is cured to obtain an electrically active silicone elastomer that has an increased specific dielectric constant.
  • An organic silicon compound having highly dielectric groups may be added separately from the component used for curing in this curable composition.
  • an organic compound having highly dielectric groups and functional groups reactive with the reactive organopolysiloxane contained in the curable composition is added to the curable organopolysiloxane composition, thereby increasing specific dielectric constant of the electrically active silicone elastomer obtained by curing.
  • highly dielectric groups are introduced into the electrically active silicone elastomer obtained by curing.
  • an organic compound miscible with the curable organopolysiloxane composition and having highly dielectric groups is added to the curable organopolysiloxane composition, and thus the specific dielectric constant of the electrically active silicone elastomer obtained by curing is increased. Due to miscibility between the organic compound and the organopolysiloxane in this curable composition, an organic compound having these highly dielectric groups is incorporated in the matrix of the electrically active silicone elastomer obtained by curing.
  • the highly dielectric group in the present invention may be any group capable of increasing dielectric properties of the obtained cured article obtained by curing the curable organopolysiloxane composition of the present invention in comparison to the dielectric properties when the group is not contained.
  • examples of the highly dielectric group used in the present invention are listed below.
  • the halogen atom-containing group may be selected as an organic group having one or more atoms of one or more types selected from fluorine atom and chlorine atom, as exemplified by halogenated alkyl groups, halogenated aryl groups, and halogenated aryl alkyl groups.
  • halogen-containing organic groups include the chloromethyl group, 3-chloropropyl group, 3,3,3— trifluoropropyl group, and perfluoroalkyl group, without limitation.
  • Nitrogen atom-containing groups are exemplified by the nitro group, cyano groups (e.g.
  • the oxygen atom-containing group is exemplified by ether groups, carbonyl groups, and ester groups.
  • the heterocyclic group is exemplified by an imidazole group, pyridine group, furan group, pyran group, thiophene group, phthalocyanine group, and complexes of such.
  • the boron-containing group is exemplified by borate ester groups and boric acid salt groups. f) Phosphorous-containing Groups
  • the phosphorous-containing group is exemplified by the phosphine group, phosphine oxide group, phosphonate ester group, phosphite ester group, and phosphate ester group.
  • the sulfur-containing group is exemplified by the thiol group, thioether group, sulfoxide group, sulfone group, thioketone group, sulfonate ester group, and sulfonamide group.
  • the curable organopolysiloxane composition for transducers of the present invention may comprise additives normally blended in organopolysiloxane compositions. As long as the object of the curable organopolysiloxane composition for transducers of the present invention is not impaired, it is possible to blend any additives, such as a curing retardant (curing suppression agent), flame retardant, heat resistance improvement agent, colorant, solvent, or the like.
  • a curing retardant curing retardant
  • flame retardant flame retardant
  • heat resistance improvement agent colorant
  • solvent solvent
  • the curing retardant is exemplified by alkyne alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1 -hexyn-3-ol, 2-phenyl-3-butyn-2-ol, or the like; enyne compounds such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne, or the like; and benzotriazole; without limitation.
  • the utilized concentration of the curing retardant (curing suppression agent), relative to the total composition (weight basis), is preferably in the range of 1 to 50,000 ppm.
  • hybridization is possible by combining the curable organopolysiloxane composition for transducers of the present invention with a polymer other than the organopolysiloxane.
  • a polymer having a higher dielectric constant than that of the organopolysiloxane with the organopolysiloxane it may be possible to increase the dielectric constant of the composition of the present invention and the cured article obtained from the composition.
  • Hybridization embraces the so-called polymer blending of the organopolysiloxane with a non-organopolysiloxane polymer, and forming a fused polymer by bonding together (i.e.
  • co-polymerization so-called co-polymerization the organopolysiloxane and the other polymer.
  • This type of hybrid co-polymers may be available as an intermediate raw material of the curable organopolysiloxane composition for transducer use by a step of adding as said curable organopolysiloxane with the filler into a composition for kneading, and of kneading the composition using an extruder or kneading apparatus
  • the curable organopolysiloxane composition of the present invention may be condensation curable, addition curable, peroxide curable, or photo-curable, although an addition curable ogranopolysiloxane composition is preferred.
  • To this curable system may be further included the introduction of an organopolysiloxane molecule chain by the method of adding the aforementioned dielectric functional group to an acrylic group, methacrylic group, epoxy group, or thiol group.
  • this photo-curable part or electron beam-curable part in addition to the addition curing reaction, it is possible to also use a photo-curing reaction or electron beam curing reaction.
  • a compound known as a monomer and/or oligomer capable of curing by light or electron beam may be further added to the aforementioned curable composition.
  • a so-called photosensitizer may be added.
  • the dielectric silicone elastomer that is this member for transducers obtained by curing of the curable organopolysiloxane composition of the present invention is thermally molded to a sheet of 2.0 mm thickness, it is then possible to have the below listed mechanical properties as measured based on JIS K 6249. However, according to the application of this dielectric silicone elastomer and other required electrical characteristics, it is possible to use a dielectric silicone elastomer having mechanical properties outside these mechanical property ranges.
  • Young's modulus (MPa) at room temperature may be set in the range of 0.1 to 10 MPa, and the particularly preferred range is 0.1 to 2.5 MPa.
  • Tear strength (N/mm) at room temperature may be set greater than or equal to 1 N/mm, and particularly is in the range greater than or equal to 2 N/mm.
  • Tear strength (MPa) at room temperature may be set greater than or equal to 1 MPa, and particularly preferably is in the range greater than or equal to 2 MPa.
  • Elongation at break (%) may be set greater than or equal to 100%, and from the standpoint of displacement amount of the transducer, is particularly preferably in the range of 200 to 1 ,000%.
  • the dielectric silicone elastomer that is this member for transducers obtained by curing of the curable organopolysiloxane composition of the present invention has the below listed dielectric characteristics.
  • one important characteristic of the present invention is that, in addition to attainment of mechanical characteristics, such as those described above, by the composition of the present invention, the composition displays an excellent specific dielectric constant in the low frequency region.
  • the dielectric breakdown strength (V/ ⁇ ) may be set greater than or equal to 20 V/ ⁇ .
  • the dielectric breakdown strength is particularly preferably in the range greater than or equal to 30 V/ ⁇ .
  • the specific dielectric constant measured at 1 MHz measurement frequency and 23 °C measurement temperature may be set greater than or equal to 3.0.
  • the preferred specific dielectric constant will change according to the required form of the dielectric layer and the type of the transducer, a particularly preferred range of specific dielectric constant under the aforementioned measurement conditions is greater than or equal to 5.0.
  • the production method of the curable organopolysiloxane composition of the present invention is described in above.
  • the curable organopolysiloxane composition is preferably produced by using a twin screw extruder having a free volume of at least 5,000 (LVh) to knead the reactive organopolysiloxane component, dielectric inorganic fine particles, and a surface treatment agent, the present invention may form the Master Batch etc. comprising a high concentration (e.g. at least 80% by weight) of filler. Then the other reactive organopolysiloxane components, curing catalyst, and other components are preferably added and kneaded to produce the curable organopolysiloxane composition.
  • Dielectric inorganic fine particle are dispersed well and at high density in the curable
  • organopolysiloxane composition of the curable organopolysiloxane composition for transducers obtained by the aforementioned production method, and it is thus possible to produce a member for transducers that has good electrical characteristics and mechanical characteristics.
  • this temperature is set in the range of 40 °C to 200 °C, and may be set in the range of 100°C to 180°C.
  • the residence time during treatment may be set to about 30 seconds to 5 minutes.
  • the method for molding the curable organopolysiloxane composition into a film-like shape is exemplified by a method of forming a coating film by coating of the curable organopolysiloxane composition on a substrate using previously widely known coating methods, a method of molding by passing the curable organopolysiloxane composition through an extruder equipped with a slot of the desired shape, or the like.
  • Thickness of this type of film-like curable organopolysiloxane composition may be set in the range of 0.1 ⁇ to 5,000 ⁇ , for example. Depending on the aforementioned coating method and the absence or presence of a volatile solvent, thickness of the obtained cured article may be made thinner than thickness at the time of application of the composition.
  • thermal curing, room temperature curing or curing by high energy beam irradiation may be performed, while optionally applying an electrical field or magnetic field in a target orientation direction for the dielectric inorganic fine particles, or after orienting of the filler by application of a magnetic field or electrical field for a fixed time period.
  • curing is preferably performed in the temperature range of 90 °C to 180°C by retention in this temperature range for 30 seconds to 30 minutes.
  • the silicone elastomer for transducers may be stacked as one layer or 2 or more layers. Furthermore, an electrode layer may be provided at both tips of the dielectric elastomer layer, and a configuration may be used in which the transducer itself is composed of multiple stacked electrode layers and the dielectric elastomer layers. Thickness of the silicone elastomer for transducers per single layer for such a configuration may be 0.1 ⁇ to 1 ,000 ⁇ . If such layers are stacked as at least 2 layers, the thickness per single layer may be 0.2 ⁇ to 2,000 ⁇ .
  • organopolysiloxane composition on the same cured layer to repeatedly coat and cure to stack layers; (2) coating the curable organopolysiloxane composition in a stacked manner on the substrate in an uncured or semi-cured state, and curing the entire curable organopolysiloxane compositions that have been coated in a stacked manner; or a method that combines the (1 ) and
  • the curable organopolysiloxane composition may be applied on the substrate by die coating, may be cured, 2 or more such silicone elastomer cured layers may be formed by stacking, and the silicon elastomer cured layers may be attached to the electrode layer for manufacture in the present application invention.
  • the 2 or more stacked silicon elastomer cured layers are preferably dielectric layers, and the electrode is preferably an electrically conductive layer.
  • the transducer having the multilayered configuration of the present invention after coating of a single layer containing the organopolysiloxane composition, may be produced by coating a layer that comprises a different organopolysiloxane composition. Moreover, production is possible by simultaneously coating multiple layers containing each organopolysiloxane composition.
  • the thin film-like silicone elastomer that is the member for transducers may be obtained by coating the aforementioned curable organopolysiloxane composition on the substrate, and then curing the assembly at room temperature and by heating, or by curing using high energy beam irradiation such as ultraviolet radiation or the like. Moreover, when the thin film-like dielectric silicone elastomer is stacked, uncured curable organopolysiloxane composition may be applied on the cured layer and then cured sequentially, or the uncured curable organopolysiloxane composition may be stacked in layers, and then the layers may be cured simultaneously.
  • the aforementioned thin film-like silicone elastomer is particularly useful as a dielectric layer for a transducer. It is possible to form a transducer by arrangement of electrode layers at both ends of the thin film-like silicone elastomer. Furthermore, by blending electrically conductive inorganic particles into the curable organopolysiloxane composition of the present invention, it is possible to provide functionality as an electrode layer. Furthermore, the "electrode layer" in the patent specification of the present invention is sometimes simply referred to as the "electrode.” [0137]
  • Film thickness is generally 1 ⁇ to 2,000 ⁇ , and the film may have a structure that is a single layer, two or more layers, or a further number of stacked layers.
  • the stacked electrically active silicone elastomer layers when used as dielectric layers, may be used with a film thickness of 5 ⁇ to 10,000 ⁇ , or such layers may be stacked to obtain greater thickness.
  • the thin film-like silicone elastomer layer that is this member for transducers may be formed by stacking the same thin film-like silicone elastomer, or thin film-like silicone elastomers of 2 or more different physical characteristics or pre-curing compositions may be stacked to form this member for transducers.
  • the function of the thin film-like silicone elastomer layer may be a dielectric layer or an electrode layer.
  • thickness of the dielectric layer is 1 to 1 ,000 ⁇
  • thickness of the electrode layer is 0.05 ⁇ to 100 ⁇ .
  • the transducer of the present invention is characterized as having this member for transducers produced by curing of the curable organopolysiloxane composition for transducers of the present invention, and the transducer of the present invention may have a structure that particularly comprises a highly stacked layer structure (i.e. 2 or more dielectric layers).
  • the transducer of the present invention further may have a structure that comprises 3 or more dielectric layers.
  • the transducer that has this type of highly stacked structure is able to generate greater force by comprising multiple layers. Moreover, by stacking of layers, it is possible to obtain greater displacement than would be obtained by using a single layer.
  • An electrode may be comprised at both ends of the dielectric layer for transducers of the present invention.
  • the utilized electrode substance is exemplified by metals and alloys of metals such as gold, platinum, silver, palladium, copper, nickel, aluminum, titanium, zinc, zirconium, iron, cobalt, tin, lead, indium, chromium, molybdenum, manganese, or the like; metal oxides such as indium-tin compound oxide (ITO), antimony-tin compound oxide (ATO), ruthenium oxide, titanium oxide, zinc oxide, tin oxide, and the like; carbon materials such as carbon nanotubes, carbon nano-horns, carbon nanosheets, carbon fibers, carbon black, or the like; and electrically conductive resins such as poly(ethylene-3,4-dioxythiophene) (PEDOT), polyaniline, polypyrrole, or the like. Electrically conductive elastomers and electrically conductive resin having electrically conductive fillers dispersed in the resin can
  • the electrode may comprise one substance alone from among the aforementioned electrically conductive substances, or may comprise 2 or more such electrically conductive substances. If the electrode comprises 2 or more types of electrically conductive substances, one of the electrically conductive substances may function as the active substance, and the remaining electrically conductive substances may function as conductive materials for lowering resistance of the electrode.
  • the total thickness of the dielectric layer for transducers of the present invention may be set in the range of 10 ⁇ to 2,000 ⁇ (2 mm), although this total thickness may be particularly set to a value greater than or equal to 200 ⁇ .
  • thickness per single layer of the dielectric silicone elastomer layer forming the dielectric layer is preferably 0.1 to 500 ⁇ , and this thickness is particularly preferably 0.1 to 200 ⁇ .
  • transducer in the present invention is taken to mean an element, machine, or device for conversion of a certain type of energy to a separate type of energy.
  • This transducer is exemplified by artificial muscles and actuators for conversion of electrical energy into mechanical energy; sensors and electricity generating elements for conversion of mechanical energy into electrical energy; speakers, microphones, and headphones for conversion of electrical energy into sound energy; fuel cells for conversion of chemical energy into electrical energy; and light emitting diodes for conversion of electrical energy into light energy.
  • the transducer of the present invention is capable of use particularly as an artificial muscle, actuator, sensor, or electrical generating element due to the dielectric and mechanical characteristics of the transducer of the present invention.
  • An artificial muscle is anticipated to be used for applications such as robots, nursing equipment, rehabilitation training equipment, or the like.
  • An embodiment as an actuator will be explained below as an example of the present invention.
  • FIG. 1 shows a cross sectional view of an actuator 1 of the present embodiment in which dielectric layers are stacked.
  • the dielectric layer is composed of 2 dielectric layers, for example.
  • the actuator 1 is equipped with dielectric layers 10a and 10b, electrode layers 11 a and 11 b, a wire 12, and an electrical power source 13.
  • the electrode layers 11 a and 11 b cover a respective contacting surface of the dielectric layer, and these are connected to the electrical power source 13 through respective wires 12.
  • the actuator 1 may be driven by application of a voltage between the electrode layer 11 and the electrode layer 11 b.
  • a voltage between the electrode layer 11 and the electrode layer 11 b.
  • the dielectric layers 10a and 10b become thinner due to dielectric properties, and this results in elongation parallel to the faces of the electrode layers 11 a and 11 b. That is to say, it is possible to convert electrical energy into force or mechanical energy of movement or displacement.
  • FIG. 2 shows a cross sectional view of an actuator 2 of the present embodiment in which the dielectric layer and electrode layer are stacked.
  • the dielectric layer is composed of 3 layers
  • the electrode layer is composed of 4 layers, for example.
  • the actuator 2 is equipped with dielectric layers 20a, 20b, and 20c, electrode layers 21 a, 21 b, 21 c and 21 d; the wire 22; and the electrical power source 23.
  • the electrode layers 21 a, 21 b, 21 c, and 21 d each cover a respective contacting surface of dielectric layer, and these are connected to the electrical power source 23 through respective wires 22.
  • the electrode layers are connected alternatingly to sides of different voltage, and the electrode layers 21 a and 21 c are connected to a different side from that of the electrode layers 2b and 21 d.
  • an actuator when mechanical energy (such as pressure or the like) is applied from outside to the transducer of the present invention, it is possible to generate an electrical potential difference as electrical energy between the mutually insulated electrode layers. That is to say, use is possible as a sensor for the conversion of mechanical energy into electrical energy. This embodiment of a sensor will be described below.
  • FIG. 3 shows structure of the sensor 3 of the present embodiment.
  • the sensor 3 has a structure in which the dielectric layer 30 is disposed between upper electrode layers 31 a, 31 b, and 31 c and lower electrode layers 32a, 32b, and 32c arranged in a matrix-like pattern.
  • the electrode layers are disposed in a matrix pattern of 3 rows in the vertical direction and horizontal direction, respectively.
  • the face of each electrode layer not contacting the dielectric layer 30 may be protected by an insulating layer.
  • the dielectric layer 30 may comprise 2 or more layers of the same dielectric layer containing organopolysiloxane.
  • this embodiment may be used as a sensor for conversion of mechanical energy into electrical energy.
  • the opposing electrode layers sandwiching the dielectric layer were formed as 3 pairs in the sensor 3 of the present embodiment, the number, sizes, placement, or the like of electrodes may be selected appropriate according to application.
  • An electricity generating element is a transducer for conversion of mechanical energy into electrical energy.
  • This electricity generating element may be used for devices that generate electricity, beginning with electricity generation by natural energy such as wave power, water power, water power, or the like, as well as generation of electricity due to vibration, impact, pressure change, or the like. An embodiment of this electricity generating element will be described below.
  • FIG. 4 shows a cross sectional view of the electricity generating element 4 of the present embodiment, in which dielectric layers are stacked.
  • the dielectric layer is composed of 2 dielectric layers, for example.
  • the electricity generating element 4 is composed of the dielectric layers 40a and 40b and the electrode layers 41 a and 41 b.
  • the electrode layers 41 a and 41 b are arranged covering one face of the respective contacted dielectric layer.
  • the electrode layers 41 a and 41 b are connected electrically to a non-illustrated load.
  • This electricity generating element 4 may generate electrical energy by change of the static capacitance by change of the distance between the electrode layers 41 a and 41 b. That is to say, due to change in the shape of the element between the electrode layers 41 a and 41 b in the electrostatic charge-induced state due to electrostatic field formed by the dielectric layers 40a and 40b, the charge distribution becomes biased, the static capacitance between electrode layer changes due to such bias, and an electrical potential difference arises between the electrode layers.
  • the transducer of the present invention may operate in air, water, vacuum, or organic solvent. Moreover, the transducer of the present invention may be sealed appropriately according to the environment of use of the transducer. No particular limitation is placed on the sealing method, and this sealing method is exemplified by sealing using a resin material or the like.
  • the curable organopolysiloxane composition for transducers of the present invention may be used appropriately for the manufacture of a transducer.
  • the curable organopolysiloxane composition for transducers of the present invention may comprise a so-called B stage material in a state in which the reactive organopolysiloxane is partially reacted, and curing is incomplete.
  • a B stage material of the present invention is exemplified by a material in a state that is gel-like or has flowability.
  • the embodiments of the present invention also comprise a member in a state where the curing reaction of the curable organopolysiloxane composition for transducers has partially progressed, and in which the member for transducers is in a state that is gel-like or fluid.
  • the member for transducers in this type of semi-cured state may be composed of a single layer or stacked layers of the thin film-like silicone elastomer.
  • This silicone elastomer composition was press cured for 15 minutes at 150°C, and then was post-cured in an oven for 60 minutes at 150°C. Based on J IS K 6249, Young's modulus, tensile strength, elongation at break, and tear strength were measured for the obtained cured article. In order to measure mechanical strength, a sheet of 2 mm thickness was made.
  • the silicone elastomer composition was press cured for 15 minutes at 150°C to produce a 0.07 mm thick sheet, and insulation breakdown strength as measured using an electrical insulation breakdown voltage oil tester, i.e. PORTATEST 100A-2 manufactured by Soken Electric Co., Ltd.
  • the silicon elastomer composition was press cured for 15 minutes at 150 °C for 15 minutes to produce a sheet of 1 mm thickness.
  • Specific dielectric constant was measured under 23 °C temperature and 1 MHz measurement frequency conditions using a TR-1100 dielectric constant-tangent measurement device manufactured by Ando Electric Co., Ltd.
  • the same sample was evaluated for volume resistivity using a model 4339A high resistance meter (volume resistance measurement device, manufactured by HP).
  • the kneading conditions of the twin screw kneading apparatus were as follows: ⁇ 50 1 jacket temperature, and 1 minutes residence time.
  • the feed rate of the dimethylpolysiloxane A and trimethylmethoxysilane mixture was 4 kg/hr, and the feed rate of the titanium oxide was 16 kg/hr.
  • the concentration of titanium oxide in the obtained silicone elastomer base was about 76 mass%.
  • the mixture was blended uniformly (about 10 minutes), and a silicone rubber composition
  • Silicone elastomer compositions may be prepared by following examples of compositional formulation, and using intermediate raw materials of silicone elastomer bases obtained by keading procedure with the twin screw kneading apparatus of the Practical Example 1. The production method is excellent in the performance, mass-productivity and the like of the silicone elastomer composition for transducer use of this present invention.
  • dimethylpolysiloxane (B 2 ) (0.23% vinyl content) having a viscosity of 2,000 mPa-s at 25 °C and capped by dimethylvinylsiloxy groups at both terminals are added 85.35% spherical barium titanate of 1 .0 ⁇ average particle diameter (produced by Fuji Titanium Industry Co., Ltd., HPBT-1 B), 0.356% trimethoxysilyl singly-terminated dimethylvinyl singly-terminated
  • dimethylsiloxane-methylhydrogensiloxane copolymer (A 22 , 0.83% SiH content), 0.67% (as platinum) of the platinum complex of 1 ,3— diethenyl— 1 ,1 ,3,3-tetramethyldisiloxane complex dissolved in dimethylvinylsiloxy group doubly terminated methylpolysiloxane, as well as tetramethyltetravinylcyclotetrasiloxane as a reaction control agent.
  • the mixture is mixed until uniform (about 10 minutes) to obtain a silicone elastomer composition.
  • the molar ratio of all SiH functional groups over all vinyl groups in this silicone elastomer composition (SiH groups/vinyl groups) is 1.3.
  • dimethylsiloxane-methylhydrogensiloxane copolymer 0.75% SiH content
  • 80 ppm platinum, the platinum metal content is calculated by mass parts and to said mixture of dimethylpolysiloxanes in the silicone elastomer bases) of the platinum complex of
  • the molar ratio of all SiH functional groups over all vinyl groups in this silicone elastomer composition is 1.3.
  • dimethylsiloxane-methylhydrogensiloxane copolymer 0.75% SiH content
  • 80 ppm platinum, the platinum metal content is calculated by mass parts and to said mixture of
  • the molar ratio of all SiH functional groups over all vinyl groups in this silicone elastomer composition is 1.3.
  • dimethylsiloxane-methylhydrogensiloxane copolymer 0.75% SiH content
  • 80 ppm platinum, the platinum metal content is calculated by mass parts and to said mixture of
  • the molar ratio of all SiH functional groups over all vinyl groups in this silicone elastomer composition is 1.3.
  • dimethylpolysiloxane (A 22 ) (0.23% vinyl content) having a viscosity of 2,000 mPa-s at 25 °C and capped by dimethylvinylsiloxy groups at both terminals are added 85.35% spherical barium titanate of 1 .0 ⁇ average particle diameter (produced by Fuji Titanium Industry Co., Ltd., HPBT-1 B), 0.356% trimethoxysilyl singly-terminated dimethylvinyl singly-terminated
  • dimethylpolysiloxane (A 22 ) (0.23% vinyl content) having a viscosity of 2,000 mPa-s at 25 °C and capped by dimethylvinylsiloxy groups at both terminals are added 50.00% of Carbon Black (produced by Cancarb corporation, Thermax Floform N990).
  • Carbon Black produced by Cancarb corporation, Thermax Floform N990.
  • the curable organopolysiloxane composition was obtained by the production method of present invention , and thus a silicone elastomer was provided that had excellent mechanical characteristics (as represented by elongation at break) and dielectric characteristics (as represented by the dielectric constant). Moreover, by optimization of the crosslinking structure and the inorganic fine particles, it is possible to design a material according to the desired transducer application.
  • the silicone elastomer obtained from the curable organopolysiloxane composition of the present invention attains high dielectric properties even in the low voltage region.

Abstract

The present invention provides a production method of curable organopolysiloxane composition capable of producing a cured article that can be used as a transducer and provided with excellent mechanical characteristics and/or electrical characteristics. The present invention also relates to a production method of a curable organopolysiloxane composition for transducer use comprising a step of kneading a composition for kneading including: a curable organopolysiloxane, and at least one type of filler, wherein the kneading is performed using an extruder or kneading apparatus.

Description

PRODUCTION METHOD OF
CURABLE ORGANOPOLYSILOXANE COMPOSITION FOR TRANSDUCERS
TECHNICAL FIELD
[0001 ]
The present invention relates to a production method of a curable organopolysiloxane composition capable of use with advantage for transducers. The present invention provides a production method of a curable organopolysiloxane composition for which the
organopolysiloxane cured article formed by curing is used as an electrically active silicone elastomer material capable of use as the dielectric layer or electrode layer of a transducer. The present invention particularly relates to a production method of a curable organopolysiloxane composition having electrical characteristics and mechanical characteristics suitable for a material used as a dielectric material, and, further, particularly for use as a dielectric layer of a transducer. The present invention further relates to a production method for an electrically active polymer material formed using a curable organopolysiloxane composition, and to a component of a transducer containing this electrically active polymer material.
BACKGROUND ART
[0002]
A. G. Benjanariu, et. al., indicated that dielectric polymers are potential materials for artificial muscles (A. G. Benjanariu, et. al., "New elastomeric silicone based networks applicable as electroactive systems," Proc. of SPIE vol. 7976 79762V-1 to 79762V-8 (2011 )). Here, they showed the physical characteristics of a material having a unimodal or bimodal network formed with an addition-curable silicone rubber. To form this silicone rubber, a linear chain
poly(dimethylsiloxane) (PDMS) polymer having vinyl groups is crosslinked using a short chain organohydrogensiloxane having 4 silicon-bonded hydrogen atoms as the crosslinking agent. Moreover, in B. Kussmaul et al., Actuator 2012, 13th International Conference on New Actuators, Bremen, Germany, 18-20 June 2012, pp. 374 to 378, there is mention of an actuator that sandwiches a dielectric elastomer material, which is an organopolydimethylsiloxane that has been chemically modified by groups functioning as electrical dipoles, between electrodes, the modification being performed by bonding the groups to polydimethylsiloxane using a crosslinking agent.
[0003]
However, no specific composition is disclosed and no production process and production apparatus suitable for industrial production are disclosed for the curable organopolysiloxane composition in either of the aforementioned references. Furthermore, in practice, the physical properties of the curable organopolysiloxane compositions are insufficient for materials for industrial use in various types of transducers. Thus, a production method is needed that is capable of industrially producing an electrically active polymer material that combines mechanical characteristics and electrical characteristics capable of being satisfactory in actual use as a material for various types of transducers. In particular, there is strong need for a production method of a curable organopolysiloxane composition that cures and provides an electrically active polymer material having excellent physical characteristics.
BACKGROUND DOCUMENTS
[0004]
Non-patent Document 1 : "New elastomeric silicone based networks applicable as electroactive systems," Proc. of SPIE vol. 7976 79762V-1 to 79762V-8 (2011 )
Non-patent Document 2: Actuator 2012, 13th International Conference on New Actuators, Bremen, Germany, 18-20 June 2012, pp. 374 to 378
Technical Problem
[0005]
An object of the present invention is to provide a production method of a curable
organopolysiloxane composition capable of producing a cured article that can be used as a transducer and provided with excellent mechanical characteristics and/or electrical
characteristics.
[0006]
Another object of the present invention is to provide a production method of a curable organopolysiloxane composition capable of realizing a high energy density by providing excellent mechanical characteristics and/or electrical characteristics, and particularly a high specific dielectric constant, high dielectric breakdown strength, and low Young's modulus; able to achieve durability and a practical displacement amount due to excellent mechanical strength (i.e. tensile strength, tearing strength, elongation, or the like) in the case of use as a dielectric layer of a transducer; and able to produce a cured article capable of use as a material for use in transducers.
[0007]
Moreover, an object of the present invention is to provide a method for production of a curable organopolysiloxane composition for transducers that is able to readily obtain an intermediate raw material of a curable organopolysiloxane composition for transducers (i.e. intermediate raw material that is a silicone rubber compound containing the raw material polymer blended with a high concentration of various types of fillers, sometimes referred to hereinafter as a "master batch" or "silicone elastomer base"), so that when the intermediate raw material is used, the production efficiency and the performance of the obtained cured product are excellently improved. Furthermore, an object of the present invention is to provide a method for production of a curable organopolysiloxane composition for transducers capable of advantageous production from the standpoint of a component used for transducers in that a uniform sheet-like cured product may be obtained, a thin film may be produced, electrical characteristics or mechanical characteristics of the obtained sheet-like cured product are excellent, and handling ability is excellent for lamination or the like.
Solution To Problem
[0008]
The present invention was achieved by the discovery by the inventors that the present invention can solve the aforementioned problems by a production method of a curable organopolysiloxane composition for transducer use comprising a step of kneading a composition for kneading including: a curable organopolysiloxane, and at least one type of filler, wherein the kneading is performed using an extruder or kneading apparatus.
[0009]
Preferably, the composition for kneading further include (D) dielectric inorganic fine particles having specific dielectric constant at 1 kHz greater than or equal to 10 at room temperature as the at least one type of filler. More preferably, the composition further includes at least one type of surface treatment agent. Furtheremore, the extruder or kneading apparatus is preferred to be at least one mechanical means selected from the group consisting of twin screw extruders, twin screw kneaders, and single screw blade-type extruders, and more preferred to be a twin screw extruder having a device free volume as defined below that is at least 5,000 (L/hr), is at least 7,500 (L/hr), or is at least 10,000 (L/hr).
Free volume: void cross-sectional area of the apparatus (mm2) χ screw pitch (mm) χ rotation rate (rpm) χ 60/1 ,000,000 (L/hr)
Advantageous Effects of Invention
[0010]
According to the production method of a curable organopolysiloxane composition for transducers of the present invention, the filler is well dispersed in the curable organopolysiloxane, and it is thus possible to produce a member for transducers having good electrical characteristics or mechanical characteristics. Moreover, it is possible to provide a production method of a curable organopolysiloxane composition for transducers capable of a higher filling amount of filler in the curable organopolysiloxane, and capable of obtaining a uniform film-like cured product during production of the member for transducers, so that electrical characteristics or mechanical characteristics of the obtained film-like cured product are improved, and handling ability for lamination or the like is excellent.
[0011 ] According to the production method of a member for transducers of the present invention, it is possible to produce a member for transducers in which the filler is well dispersed in the silicone elastomer, and it is thus possible to produce a member for transducers having good electrical characteristics or mechanical characteristics.
DETAILED DESCRIPTION OF THE INVENTION
[0012]
The present invention will be explained below in detail.
The production method of a curable organopolysiloxane composition for transducer use of the present invention is characterized by comprising a step of kneading a composition for kneading including: a curable organopolysiloxane, and at least one type of filler, wherein the kneading is performed using an extruder or kneading apparatus.
[0013]
By the production method of a curable organopolysiloxane composition for transducer use of the present invention, it is possible to improve electrical characteristics and mechanical characteristics of the member for transducers produced by curing the composition.
Furthermore, by use of the production method, it is possible to produce a member for transducers having good quality when film thickness is reduced. In addition, by the use of the production method, it is possible to readily obtain an intermediate raw material in which various types of fillers are blended at high concentration in the curable organopolysiloxane (i.e. raw material), and the production of the final composition may be readily accomplished. Each of the configurations will be described below.
[0014]
The curable organopolysiloxane composition produced by and according to the present invention is a composition for curing to produce a member for transducers. The curable
organopolysiloxane composition produced according to the present invention particularly may have filler dispersed at high concentration in the curable organopolysiloxane. This type of curable organopolysiloxane composition may itself be used to produce a member for transducers by curing by heating or the like, or alternatively, this type of curable organopolysiloxane composition may be used as an intermediate raw material (i.e. master batch, silicone elastomer base or silicone rubber compound) for production of a member for transducers.
[0015]
In particular, upon use of the curable organopolysiloxane composition as an intermediate raw material (master batch, silicone elastomer base or silicone rubber compound), blending with another component such as a curable organopolysiloxane or the like is readily possible at a desired formulation using of a desired kneading apparatus, and thus the production efficiency is excellent. Moreover, during the kneading, it is possible to also perform surface treatment of the filler by the addition of at least one type of surface treatment agent to the composition for kneading.
[0016]
[Curable Organopolysiloxane]
No particular limitation is placed on the curable organopolysiloxane as long as the curable organopolysiloxane is curable by condensation curing reaction, addition curing reaction, peroxide compound curing reaction, photocuring reaction, or by drying and solidification upon removal of a diluent solvent. The curable organopolysiloxane may be used as a combination of two or more types of different curable organopolysiloxanes.
[0017]
The curable organopolysiloxane curing by an addition curing mechanism is exemplified by organohydrogenpolysiloxanes having at least 2 silicon-bonded hydrogen atoms in a molecule and/or organopolysiloxanes having at least 2 alkenyl groups in a molecule. Moreover, for the addition curing mechanism of said curable organopolysiloxanes, the curable composition further comprises a hydrosilylation reaction catalyst.
[0018]
The organopolysiloxane curable by condensation curing mechanism is exemplified by diorganopolysiloxanes that are liquid at room temperature and having molecular terminals capped by silanol groups or silicon-bonded hydrolyzable groups, or partially hydrolyzed condensates of organosilanes having silicon-bonded hydrolyzable groups. During curing, said diorganopolysiloxane or said partially hydrolyzed condensate of organosilane further includes an organosilane or organosiloxane type crosslinking agent having a sufficient amount of silicon-bonded hydrolyzable groups for crosslinking these components. Moreover, for the condensation curing mechanism of said curable organopolysiloxanes, the curable composition further comprises a condensation reaction promotion catalyst.
[0019]
In addition to the organopolysiloxanes curable by the addition curing mechanism and condensation curing mechanism, the curable organopolysiloxane of the present invention may be an organopolysiloxane curable by peroxide compound curing mechanism, for example. In the case of an organopolysiloxane curable by the peroxide compound curing mechanism, the organopolysiloxane is generally exemplified by organopolysiloxane raw rubbers. Moreover, during curing of said organopolysiloxane raw rubber, an organic peroxide compound should be added.
[0020]
Preferably, the curable organopolysiloxane is a hydrosilylation reaction curable organopolysiloxane. More specifically, the organopolysiloxane may be at least one of (A11 ) at least one type of organohydrogenpolysiloxane having silicon atom-bonded hydrogen atoms at both molecular terminals, a weight fraction of hydrogen atoms being 0.1 to 1 .0% by weight;(A12) at least one type of organohydrogenpolysiloxane having at least 3 silicon atom-bonded hydrogen atoms in a single molecule, a weight fraction of hydrogen atoms being 0.03 to 2.0% by weight; and (A2) at least one type of organopolysiloxane having at least 2 alkenyl groups in a single molecule, a weight fraction of the alkenyl groups being 0.05 to 0.5% by weight.
Furtheremore, the preferable compositional formulation and structure of the entire curable organopolysiloxane composition for transducer use is described in details in later parts.
[0021 ]
[Filler]
The at least one type of filler may be at least one type of filler selected from the group consisting of high dielectric fillers, high electrical conductivity fillers, electrically insulating fillers, and reinforcing fillers. This filler may be used as a single type or as a combination of two or more types. In particular, when the filler is used in the dielectric layer or electrode layer of a transducer, one type or two or more types of filler are preferably used that contain a high dielectric filler and/or high electrical conductivity filler.
[0022]
From a viewpoint of electric property of the member for transuducers, however, the filler is preferred to be dielectric fine particles or electrically conductive fine particles, especially, preferred to contain (D) dielectric inorganic fine particles having a specific dielectric constant at 1 kHz of greater than or equal to 10 at room temperature. The preferable dielectric inorganic fine particles is exemplified by one or more types of inorganic fine particles selected from the group consisting of titanium oxide, barium titanate, strontium titanate, lead titanate zirconate, and barium titanate, and composite metal oxides in which the barium and titanium positions of barium titanate are partially replaced by an alkaline earth metal, such as calcium or strontium; zirconium; or rare earth metal such as yttrium, neodymium, samarium, or dysprosium, and titanium oxide and barium titanate are most preferred. Furthermore, the filler component of the entire curable organopolysiloxane composition for transducer use is described in details in later parts.
[0023]
[Surface Treatment Agent]
Although said filler is particularly preferably partially or entirely surface-treated, at least one type of surface treatment agent is particularly preferably further kneaded in the composition for kneading in the kneading step. The types of treatment agents is preferred to be an
hydrophobizing surface treatment agent, more preferably, the surface treatment agent is exemplified by at least one of hydrophobizing surface treatment agent selected from the group consisting of organic titanium compounds, organic silicon compounds, organic zirconium compounds, organic aluminum compounds, and organic phosphorous compounds. The capable types of surface treatment agent of the entire curable organopolysiloxane composition for transducer use is described in details in later parts. By addition of the surface treatment agent at the time of kneading by the extruder or kneading apparatus, the treatment agent treats the surface of the filler in an efficient manner, dispersibility of the filler is improved, physical properties of the component for transducers produced using this curable organopolysiloxane composition may be effectively improved, and higher filling content and processability of the filler in the intermediate raw material obtained during this kneading step are improved.
[0024]
[Other components]
The curable organopolysiloxane composition produced according to the present invention may further include at least one type of component selected from organopolysiloxanes having a high dielectric functional group, organic compounds having a high dielectric functional group
(excluding organopolysiloxanes contributing to the curing reaction), electrical insulation improvement agents, and release agents, vulcanizing agents, curing catalysts, or the like.
These components may be contained together with said components in the composition for kneading, and the mixture may be kneaded using an extruder or kneading apparatus. Moreover, part of the other components may be kneaded with said components of the composition for kneading using an extruder or kneading apparatus so as to produce an intermediate raw material of the curable organopolysiloxane composition, and the remainder of the other components may be blended with the intermediate raw material. Details of these components will be described in later parts.
[0025]
[Production of Intermediate Raw Material (Master Batch, Silicone Elastomer Base, or Silicone Rubber Compound)]
The production method of the present invention has a step of using an extruder or kneading apparatus to knead a composition for kneading that includes said curable organopolysiloxane, and the filler, and preferably, further includes the surface treatment agent. This step enables uniform and higher filling content of the filler in the curable organopolysiloxane composition and simultaneously performing surface treatment of the filler due to the curable organopolysiloxane and the surface treatment agent. This step is thus extremely useful as a production step for intermediate raw material for a curable organopolysiloxane composition for transducers. This intermediate raw material is termed a "master batch", "Silicone Elastomer Base" or "silicone rubber compound" (hereafter, the "Master batch etc."). This intermediate raw material is advantageous for the production of a curable organopolysiloxane composition for transducers due to advantages such as the ability to use a desired blending apparatus for kneading at a desired concentration with other raw materials such as other curable organopolysiloxane raw materials, fillers, or the like, ease of designing composition of the product, and excellent production efficiency. Furthermore, due to high filling content of the filler, the curable organopolysiloxane composition becomes highly viscous. It is thus possible to impart high shear force in the step of the present invention of kneading using the extruder or kneading apparatus. Thus, due to production of a curable organopolysiloxane composition that has good dispersibility of the filler, it is possible to improve mechanical characteristics and electrical characteristics of the member for transducers obtained using this curable organopolysiloxane composition. Furthermore, as a result of uniform dispersal of the filler, there is resistance to the occurrence of defects even upon curing and molding to form a film. It is thus possible to use a thin film as the member for transducers.
[0026]
The filler content in the intermediate raw material obtained by kneading, in the total intermediate raw material, is greater than or equal to 30 mass%, is greater than or equal to 50 mass%, is greater than or equal to 60 mass%, is greater than or equal to 70 mass%, is greater than or equal to 75 mass%, or is greater than or equal to 80 mass%. In particular, by kneading using a mechanical means that is at least one type selected from twin screw extruders, two shaft kneading apparatuses, and single screw blade type extruders, it is relatively easy to obtain the Mater Batch etc. that has a filler content of at least 80 mass% in the total intermediate raw material. The intermediate raw material loaded with filler at high concentration has excellent handling and processability due to low viscosity in comparison to use of the filler alone, it is possible to improve production efficiency, and it is possible to blend other components for a desired composition. It is thus easy to design the compositional formulation of the curable organopolysiloxane composition for transducers. Moreover, as a result of uniform dispersion of the filler at high shear force, dispersibility of the finally obtained filler in the curable
organopolysiloxane composition for transducers is improved, and there is resistance to the occurrence of defects even when the composition is molded and cured as a film. It thus becomes possible to form a thin layer type component for transducers, and mechanical characteristics and electrical characteristics are improved.
[0027]
The intermediate raw material may be an intermediate raw material having a high content of high dielectric filler or high electrical conductivity filler. The intermediate raw material is obtained by a step using at least one type of mechanical means selected from twin screw extruders, twin screw kneading apparatuses, and single screw blade type extruders such that the filler content in the composition obtained by kneading of the curable organopolysiloxane, the high dielectric filler or high electrical conductivity filler, and at least one type of surface treatment agent is greater than or equal to 30 mass%, is greater than or equal to 50 mass%, is greater than or equal to 60 mass%, is greater than or equal to 70 mass%, is greater than or equal to 75 mass%, or is greater than or equal to 80 mass% of the total composition.
[0028]
In particular, the intermediate raw material that has a filler content of greater than or equal to 70 mass%, greater than or equal to 75 mass%, or greater than or equal to 80 mass% of total mass may be blended by a desired mechanical means with other raw materials used in the curable organopolysiloxane composition, e.g. other curable organopolysiloxanes, vulcanizing agents, curing catalysts, or other ingredients. It is thus possible to readily obtain a curable
organopolysiloxane composition for transducers in which the filler and other ingredients are dispersed uniformly.
[0029]
[Kneading by Extruder or Kneading Apparatus]
The production method of the present invention is characterized by comprising a step of using an extruder or kneading apparatus to knead the composition for kneading including said each component.
[0030]
Although no particular limitation is placed on the type of the extruder or kneading apparatus used in the production of the curable organopolysiloxane composition for transducers of the present invention, the extruder or kneading apparatus is exemplified by single screw extruders, twin screw extruders, multi-screw extruders, single screw blade type extruders, twin screw kneading apparatuses, continuous kneading apparatuses, batch-type kneading apparatuses, Banbury mixers (hermetically sealed type mixers), Henschel mixers, double roll mills, triple roll mills, continuous type two roll mills, continuous type triple roll mills, batch type roll mills, pressurized kneaders, change can type mixers, planetary type mixers, continuous ball mills, conical screw mixers, ribbon blenders, double arm or sigma blade mixers, dental mixers, or the like, or combinations of such apparatuses.
[0031 ]
Among such apparatuses, in order to improve dispersibility of the filler, an extruder or kneading apparatus may be used that is capable of kneading while applying high shear force to the curable organopolysiloxane including the high viscosity filler. This type of extruder or kneading apparatus is exemplified by at least one type of mechanical means selected from twin screw extruders, twin screw kneading apparatuses, and single screw blade type extruders.
[0032]
Moreover, in the case of a combinational use of the above-described kneading apparatus or extruder, kneading may be performed by premixing the filler and curable organopolysiloxane using an extruder, kneading apparatus, blender, or the like that imparts relatively low shear force, combined with an extruder or kneading apparatus thereafter that imparts high shear force.
[0033]
The extruder, kneading apparatus, or blender for imparting relatively low shear force is exemplified by a Henschel mixer, change can mixer, planetary type mixer, conical screw mixer, ribbon blender, double arm or sigma blade mixer, dental mixer, or the like. Moreover, the aforementioned extruder or kneading apparatus may be exemplified as the extruder or kneading apparatus for imparting high shear force.
[0034]
Moreover, the kneading of the filler and the curable organopolysiloxane may be performed using a kneading apparatus or extruder by further addition of the filler and/or curable
organopolysiloxane after the above-described preparatory blending. Moreover, after kneading of the filler and the curable organopolysiloxane using the kneading apparatus or extruder, the filler and/or curable organopolysiloxane may be further added, and then kneading may be performed using a blending or kneading apparatus or extruder.
[0035]
The concentration of filler in the composition obtained by kneading the composition of the filler and curable organopolysiloxane together using the extruder or kneading apparatus in the kneading by the extruder or kneading apparatus may designed as desired so as to become (relative to the total composition) greater than or equal to 30 mass%, greater than or equal to 50 mass%, greater than or equal to 60 mass%, greater than or equal to 70 mass%, greater than or equal to 75 mass%, or greater than or equal to 80 mass%; and by use in combination with a suitable surface treatment agent, it is possible to even knead at an extremely high filler concentration resulting in 98 mass% filler content. Specifically, the concentration of the filler relative to 100 parts by mass of the curable organopolysiloxane may be in the range of 1 to 5,000 parts by mass. The lower limit of this filler concentration may be 5 parts by mass, 10 parts by mass, 25 parts by mass, 50 parts by mass, or 100 parts by mass. The upper limit of this filler concentration may be 5,000 parts by mass, 4,000 parts by mass, 3,000 parts by mass, 2,000 parts by mass, or 1 ,500 parts by mass, 1 ,000 parts by mass, or 750 parts by mass. The filler concentration may be selected appropriately according to the desired filler concentration or according to dielectric characteristics and mechanical strength. From the standpoints of industrial equipment and production efficiency, the concentration of the filler is generally selected in the range of 100 to 2,000 parts by mass.
[0036]
Although no particular limitation is set on the temperature during formation of the intermediate raw material (the Master Batch etc.) that does not include a vulcanizing agent (curing catalyst) in kneading by the extruder or kneading apparatus, this temperature may be set in the range of 40 °C to 200 °C, 80 °C to 190°C, or 100°C to 180°C. Moreover, a residence time of the treatment in a continuous process using a twin screw extruder or the like may be set to from about 30 seconds to about 5 minutes. The temperature conditions or the like during such continuous processing may be adjusted appropriately by setting temperature of the jacket of the extruder or the like.
[0037]
From the standpoint of production of an intermediate raw material (i.e. the Master Batch etc.) containing a high concentration of filler in the curable organopolysiloxane, kneading by a twin screw extruder or twin screw kneading apparatus is particularly preferably used.
[0038]
An example of a twin screw extruder is shown in FIG. 5. In a cylinder 51 , this twin screw extruder 510 is equipped with rotatable twin screws 52 connected to a drive device 53, and the cylinder 51 has an opening (feed port 51 a) for feeding material into the cylinder 51 . Due to rotational driving of the twin screws 52, the material fed into the cylinder 51 from the first feed port 51 a is sent in the direction from left to right as viewed in the figure, and this material is discharged to the exterior of the cylinder 51 from a discharge port 51 b arranged at the tip of the cylinder 51 opposite to the tip where the feed port 51 a is arranged. Along the direction of transport of the material within the cylinder 51 , the leftward direction of FIG. 5 is sometimes described hereinafter as the upstream side, and the rightward direction of FIG. 5 is sometimes described hereinafter as the downstream side. Furthermore, as may be required, a single feed port may be used as the cylinder 51 feed port, or alternatively, other feed ports may be provided in addition to the first feed port 51 a. Furthermore, control of heating and cooling is possible to obtain a desired temperature at a desired location by equipping the cylinder 51 with a heating/cooling jacket and temperature sensors (omitted from the figure). Furthermore, the rotation of the screws may be in the same direction or in mutually opposite directions.
[0039]
According to the example shown in FIG. 5, first kneading disks 52a, second kneading disks 52b, and third kneading disks 52c are arranged, in order, along the twin screws 52 from the feed port
51 a to the discharge port 51 b. These kneading disks are used for good kneading of the material within the cylinder 51. Material transported from the upstream direction is retained at the upstream side of each of the kneading disks, and due to rotation of the kneading disks, it is possible for the material to undergo kneading due to high compression and shear force. No particular limitation is placed on the cross-sectional shape of this type of kneading disk. The utilized kneading disk may have various types of shapes as exemplified by elliptical, approximately elliptical, triangular, approximately triangular, rectangular, approximately rectangular, cross shaped, approximately cross shaped, or the like.
[0040]
The feeding of each of the raw material components will be explained in detail below using the example shown in FIG. 5. Furthermore, the components other than the curable
organopolysiloxane and filler (e.g. surface treatment agent) may be each fed with raw materials to the twin screw extruder or twin screw kneading apparatus during pre-blending. Alternatively, the components other than the curable organopolysiloxane and filler may be fed to the twin screw extruder or twin screw kneading apparatus without pre-blending.
[0041 ]
According to the example shown in FIG. 5, a feeder 54 is disposed above the first feed port 51 a, and filler and curable organopolysiloxane for kneading may be fed to the feed port 51 a.
Furthermore, although not shown in the figure, in the case of arrangement of a second feed port within the cylinder 51 between the feed port 51 a and discharge port 51 b, for example, just the curable organopolysiloxane may be fed from the first feed port 51 a, and just the filler may be fed from the second feed port. Alternatively, the pre-blended mixture of filler and curable organopolysiloxane may be fed from the first feed port 51 a, and just the filler may be fed from the second feed port. Alternatively, the pre-blended mixture of filler and curable
organopolysiloxane may be fed from the first feed port 51 a, and just the curable
organopolysiloxane may be fed from the second feed port. In the case of kneading by using the second feed port for feeding just the curable organopolysiloxane, it is possible to decrease overall viscosity of the kneaded mixture including the filler, and this method is sometimes referred to as the polymer cutback method.
[0042]
If the feed port 1 a alone is used as the feed port, and if the curable organopolysiloxane cures by the addition curing mechanism, an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by (i) feeding the organohydrogenpolysiloxane (i.e. curable organopolysiloxane) and filler into the cylinder 51 through the feed port 51 a, for example. Moreover, an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by (ii) feeding the organopolysiloxane having at least two alkenyl groups in a molecule (i.e. curable organopolysiloxane) and filler into the cylinder 51 through the feed port 51 a. Moreover, an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by (iii) feeding the organohydrogenpolysiloxane, organopolysiloxane having at least two alkenyl groups in a molecule, and filler into the cylinder 51 through the feed port 51 a.
[0043] If the feed port 51 a alone is used as the feed port, and if the curable organopolysiloxane cures by the condensation curing mechanism, an intermediate raw material of the curable
organopolysiloxane composition for transducers may be prepared by feeding the
diorganopolysiloxanes that are liquid at room temperature and having molecular terminals capped by silanol groups or silicon-bonded hydrolyzable groups, or partially hydrolyzed condensates of organosilanes having silicon-bonded hydrolyzable groups, and filler through the feed port 51 a into the cylinder 51 , for example.
[0044]
If the feed port 51 a alone is used as the feed port, and if the curable organopolysiloxane cures by the peroxide compound curing mechanism, an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by feeding the component organopolysiloxane raw rubber and filler through the feed port 51 a into the cylinder 51 , for example.
[0045]
If both the first feed port 51 a and the second feed port are used (i.e. 2 feed ports are used), an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by feeding said each curable organopolysiloxane from the first feed port 51 a into the cylinder 51 , and feeding the filler into the cylinder 51 through the second feed port, for example. Moreover, an intermediate raw material of the curable organopolysiloxane composition for transducers may be prepared by feeding said each curable organopolysiloxane and the filler into the cylinder 51 through the first feed port 51 a, and further feeding said each curable
organopolysiloxane into the cylinder 51 through the second feed port (polymer cutback method).
[0046]
If the curable organopolysiloxane composition for transducers of the present invention is produced using the extruder shown in FIG. 5, the cylinder 51 may firstly be set to a certain temperature, and the drive device 53 is operated to rotate the twin screws 52. Furthermore, temperature of the cylinder 51 may vary according to location in the cylinder 51 , or alternatively, the entire cylinder 51 may be set to a fixed temperature.
[0047]
Thereafter, each of the desired and selected types of pre-mixed curable organopolysiloxane and filler are placed in the feeder 54, and the curable organopolysiloxane and filler are fed into the cylinder 51 through the feed port 51 a.
[0048]
Due to rotation and driving of the twin screws 52, the curable organopolysiloxane and filler are sent from left to right as viewed in the figure, and the curable organopolysiloxane and filler are kneaded by the inter-meshing of the twin screws 52 and the kneading effect of the kneading disks.
[0049]
Furthermore, according to the example shown in FIG. 5, the kneading disks were arranged at three locations within the cylinder 51 . However, as may be required, additional kneading disks may be provided.
[0050]
The filler and curable organopolysiloxane kneaded in this manner are discharged from the discharge port 51 b, and the curable organopolysiloxane composition for transducers or an intermediate raw material thereof may be obtained. By kneading by the twin screw extruder in this manner, it is possible to obtain an intermediate raw material for a curable organopolysiloxane composition for transducers in which a high concentration of filler is well dispersed in the organopolysiloxane, or this composition may be obtained as the curable organopolysiloxane composition for transducers itself depending on the compositional formulation.
[0051 ]
Particularly, from the standpoint of producing an intermediate raw material that blends various types of fillers at high concentration in the raw material polymer, the extruder or kneading apparatus is preferably a twin screw extruder in which the free volume as hereinafter defined of the extruder or kneading apparatus is set to greater than or equal to 5,000 (L/hr), greater than or equal to 7,500 (L/hr), or greater than or equal to 10,000 (L/hr). In particular, in order to efficiently produce an intermediate raw material (i.e. master batch etc.) that has a filler content of greater than or equal to 80 mass%, a suitable apparatus is an apparatus having a free volume of 10,000 to 30,000 (L/hr), as exemplified by a twin screw kneading apparatus such as a model 4BKRC or TEM-100 kneading apparatus.
Definition of the term "Free volume":
void cross-sectional area of the apparatus (mm2) χ screw pitch (mm) χ rotation rate (rpm) χ 60/1 ,000,000 (L/hr)
Furthermore, the free volumes of commercial devices are listed below for reference.
[Table 1 ]
Name of equipment / Void Screw Rotation Free volume,
Name of cross-sectional pitch, rate, L/hr
manufacturer area, mm rpm
mm2
BT-30 (twin) / 357.2 45 500 482
Plastics Technology
Co., Ltd.
Figure imgf000016_0001
Kurimoto, Ltd.
In the same manner, although no particular limitation is placed on the ratio of total length/inner diameter (L/D) of the apparatus, the L/D ratio is preferably less than or equal to 50, or less than or equal to 20.
[0052]
[Production Method of a Curable Organopolysiloxane Composition for Transducer Use] The production method of the member for transducers of the present invention has a step of curing the curable organopolysiloxane composition for transducer use. According to this method of production of the member for transducers, it is possible to produce a member for transducers in which the filler is well dispersed in the silicone elastomer (i.e. cured product of the curable organopolysiloxane), and thus it is possible to produce a member for transducers that has good electrical characteristics or mechanical characteristics.
[0053]
In the case of use of the intermediate raw material obtained by the production method of the present invention, prior to heat-curing the curable organopolysiloxane composition for transducers, each of the curing agents (i.e. crosslinking agents, catalysts, or polymerization initiation agents) is added to the curable organopolysiloxane composition, and as may be required, solvents and/or additives or the like are added and blended, to prepare the curable organopolysiloxane composition. These components and the entire formulation of the curable organopolysiloxane composition are described in details in later parts.
[0054]
From standpoints such as processability during production of the member of transducers, a solvent may be used for dilution of the curable organopolysiloxane composition. This type of solvent is preferably exemplified by water, and organic solvents such as lower alcohols such as ethyl alcohol, butyl alcohol, isopropyl alcohol, or the like; ketones such as methyl isobutyl ketone, methyl ethyl ketone, acetone, or the like; ethers such as dioxane, diethylene glycol dimethyl ether, tetrahydrofuran, methyl-t-butyl ether, or the like; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether acetate, or the like. In addition, methyl acetate, ethyl acetate, butyl acetate, pentyl acetate, ethyl lactate, diethyl succinate, diethyl adipate, dibutyl phthalate, dioctyl phthalate, and similar esters such as dibasic acid esters and the like; chlorinated and fluorinated hydrocarbons, trichloroethane, and similar halogenated hydrocarbons such as chlorinated hydrocarbons, fluorinated hydrocarbons, and the like; toluene, xylene, hexane, and similar hydrocarbons; and the like can be used.
[0055]
[Curable Organopolysiloxane Composition]
As far as obtained by said production method, no particular limitation is placed on the curing system, and any curing reaction system may be employed for the curable organopolysiloxane composition of the present invention. Generally, the curable organopolysiloxane composition of the present invention is cured by condensation curing system or addition curing system.
However, peroxide curing (radical-induced curing) system or high energy ray (ex. ultraviolet ray) curing system may be employed and available for the curing system of the composition.
Furthermore, the method of forming the cured body by forming a cross-linking structure in the solution state and drying with solvent removal may be employed.
[0056]
Preferably, the curable organopolysiloxane composition comprises reactive organopolysiloxane and the composition satisfys satisfies the conditions of [Characteristic 1 ] through [Characteristic 3], and the optional [Characteristic 4] and [Characteristic 5].
[Reactive Organopolysiloxane]
The curable organopolysiloxane composition of the present invention comprises the reactive organopolysiloxane represented by general formula MaMR bDcDR dTeTR fQg. In the aforementioned general formula, M represents a triorganosiloxy group, D represents a diorganosiloxy group, T represents a monoorganosiloxy group, and Q is a siloxy unit representing Si042. MR, DR, and
TR are siloxy units in which one of the R substituting groups of the siloxy units represented by M,
D, and T, respectively, is a substituting group capable of curing reaction in a condensation reaction, addition reaction, peroxide reaction, or photoreaction; although this group is preferably a group capable of addition reaction. Among these groups, in consideration of high reaction rate and low side reactions, the substituting group capable of curing reaction is preferably a group active in a hydrosilylation reaction, i.e. a silicon atom-bonded hydrogen atom or an aliphatic unsaturated bond-containing group (such as an alkenyl group of 2 to 20 carbon atoms, or the like). Moreover, the non-R substituting groups of the aforementioned reactive organopolysiloxane are preferably groups that do not participate in the addition reaction or are highly dielectric functional groups, as exemplified by alkyl groups such as the methyl group, ethyl group, propyl group, butyl group, hexyl group, or the like; aryl groups such as the phenyl group, o-tolyl group, p-tolyl group, naphthyl group, halogenated phenyl group, or the like; alkoxy groups; or the like. Among such groups, the methyl group is preferred from the standpoint of economics. Specific examples of the reactive organopolysiloxane include trimethylsiloxy group-doubly molecular chain terminated dimethylsiloxane-methylhydrogensiloxane copolymers, trimethylsiloxy group-doubly molecular chain terminated
dimethylsiloxane-methylvinylsiloxane copolymers, dimethylhydrogensiloxy group-doubly molecular chain terminated dimethylsiloxane-methylhydrogensiloxane copolymers,
dimethylvinylsiloxy group-doubly molecular chain terminated
dimethylsiloxane-methylvinylsiloxane copolymers,
methylsiloxane-dimethylsiloxane-methylhydrogensiloxane copolymers,
methylsiloxane-dimethylsiloxane-methylvinylsiloxane copolymers, dimethylhydrogen functionalized MQ resins, dimethylvinyl functionalized MQ resins, or the like.
[0057]
Number average molecular weight (Mw) of the aforementioned reactive organopolysiloxane is in the range of 300 to 10,000. Moreover, no particular limitation is placed on viscosity measured under 10 (s~1) shear rate conditions at 25 using a rheometer equipped with a cone plate of 20 mm diameter, although this viscosity is preferably in the range of 1 to 10,000 mPa-s, and particularly preferably is in the range of 5 to 5,000 mPa-s.
[0058]
[Characteristic 1 ]: Content of the Reactive Organopolysiloxane
When the proportion of the aforementioned reactive organopolysiloxane (formed such that the value of (a + c)/(b + d + e + f + g) is less than 3) relative to the entire amount of the siloxane component in the curable organopolysiloxane composition is less than 0.1 % by weight, the number of crosslink points in the polysiloxane component is excessively low, and thus mechanical strength and dielectric breakdown strength after the curing reaction are insufficient. Conversely, a proportion in excess of 25% by weight is unsuitable since the number of crosslink points is excessive, and thus post-curing elasticity is high, and break elongation is low. This proportion is preferably less than or equal to 10% by weight.
[0059]
[Characteristic 2]: Reactive Organopolysiloxane Having Groups Capable of Curing Reaction Only at Both Terminals of the Molecule
The reactive organopolysiloxane having groups capable of curing reaction only at both molecular chain terminals will be explained next. Here, the term "curing reaction-capable group" means a group that is capable of use as a group in a condensation reaction, addition reaction, peroxide reaction, or photoreaction. However, for reasons similar to those described above, this group is preferably capable of an addition reaction. Among such addition reaction capable groups, the group is preferably active in a hydrosilylation reaction, i.e. is a group containing a silicon atom-bonded hydrogen atom or aliphatic unsaturated bond-containing group (such as an alkenyl group of 2 to 20 carbon atoms, or the like). Specific examples of the reactive organopolysiloxane include dimethylhydrogensiloxy group-doubly molecular chain terminated polydimethylsiloxane and dimethylvinylsiloxy group-doubly molecular chain terminated polydimethylsiloxane. For further suitability with respect to material characteristics (e.g.
mechanical characteristics, dielectric characteristics, heat resistance characteristics, or the like), it is possible for part of the methyl groups of such polymers to be replaced by an ethyl group, propyl group, butyl group, hexyl group, or phenyl group.
[0060]
Number average molecular weight (Mw) of the reactive organopolysiloxane having curing reaction-capable groups only at both molecular chain terminals is in the range of 300 to 100,000. Moreover, although no particular limitation is placed on viscosity measured under 10 (s~1) shear rate conditions at 25 °C using a rheometer equipped with a cone plate of 20 mm diameter, this viscosity is preferably in the range of 1 to 100,000 mPa-s, and particularly preferably is in the range of 5 to 10,000 mPa-s.
[0061 ]
A proportion of this reactive organopolysiloxane having curing reaction-capable groups only at both molecular chain terminals relative to the total siloxane component in the curable organopolysiloxane composition less than 75% by weight is inappropriate in that high elongation at break may not be achieved. Conversely, when this value exceeds 99.9% by weight, the proportion of the molecule involved in the crosslinking reaction becomes low, and post-curing mechanical strength and dielectric breakdown strength are insufficient. Thus a proportion in excess of 99.9% by weight is inappropriate.
[0062]
[Characteristic 3]: Use of Two Types of Reactive Organopolysiloxanes (S) and (L)
Average molecular weight between these two groups capable of the curing reaction is less than
10,000 for the reactive organopolysiloxane (S), which is a reactive organopolysiloxane having at least two curing reaction-capable groups in a single molecule and is used in the present invention. Average molecular weight between these two groups capable of the curing reaction is greater than or equal to 10,000 and less than or equal to 150,000 for the reactive
organopolysiloxane (L), which is a reactive organopolysiloxane having at least two curing reaction-capable groups within a single molecule and is used in the present invention.. These reactive organopolysiloxanes are contained in the molecule as a short chain non-reactive polymer part and a long chain non-reactive polymer part, respectively. Here, the molecular weight between these two groups capable of the crosslinking reaction, in the case of a chain type organopolysiloxane that has reactive functional groups only at both terminals of the molecular chain, is defined as the molecular weight of the non-reactive polysiloxane part (not including the siloxy units at both terminals). In the case of molecular weight between multiple crosslinking reaction-capable groups, this is the molecular weight of the longest part.
When the component (S) and component (L) are used together in a range of 1 :99 to 40:60 as reactive organopolysiloxane raw materials, it is possible to introduce parts of different chain lengths in the silicone chain part constituting the silicone elastomer obtained by the curing reaction. By this means, it is possible to reduce permanent strain of the obtained silicone polymer, and it is possible to decrease the mechanical energy conversion loss. In particular, when the silicone elastomer of the present invention is used in the dielectric layer of a transducer, this combined use of the component (S) and component (L) has the practical advantage of increasing the energy conversion efficiency.
As mentioned previously, it is possible to use a group capable of condensation reaction, addition reaction, peroxide reaction, or photoreaction as the curing reaction-capable groups of these components. However, this is preferably an addition reaction capable group. Among addition reaction capable groups, the group is preferably a group active in a hydrosilylation reaction, i.e. a silicon atom-bonded hydrogen atom or an aliphatic unsaturated bond-containing group (such as an alkenyl group of 2 to 20 carbon atoms, or the like). Specific examples of the reactive organopolysiloxanes (S) and (L) are the examples cited as the aforementioned reactive organopolysiloxanes represented by MaMR bDcDR dTeTR fQg and the examples cited as the aforementioned reactive organopolysiloxanes having curing reaction-capable groups only at both molecular chain terminals. For the same reasons as described above, part of the methyl groups may be replaced by an ethyl group, propyl group, butyl group, hexyl group, or phenyl group.
A value of the blend ratio (weight content ratio) S:L of the component (S) to the below described component (L) that departs from the range of 1 :99 to 40:60 is inappropriate due to non-ability to satisfy at least one type of characteristic of the obtained cured article, these characteristics including high break elongation, high mechanical strength, high dielectric breakdown strength, and low elastic modulus.
[0063]
The blend ratio (molar ratio) of the silicon atom-bonded hydrogen atoms to silicon atom-bonded unsaturated hydrocarbon groups (Vi) in the polysiloxane is preferably in the range of 0.5 to 3.0.
When this blend ratio deviates from the aforementioned range, the residual functional groups remaining after curing due to the hydrosilylation reaction may adversely affect material physical properties of the cured article.
[0064]
[Characteristic 4] Number of Crosslink Points per Unit Weight after the Curing Reaction
Furthermore, the curable organopolysiloxane composition for transducers of the present invention comprises the below described (A) and (B). The number of crosslink points per unit weight after the curing reaction of the reactive polysiloxane is defined by the below listed calculation formulae based on the number average molecular weights of each component of the (A) component and (B) component, the values in the below described general formulae of a, to g, and aj to and the contents of each of the components in the composition. This number of crosslink points per unit weight after the curing reaction of the reactive polysiloxane is preferably in the range of 0.5 to 20 μιηοΙ/g, and further preferably is in the range of 0.5 to 10 μιηοΙ/g.
(A) An organohydrogenpolysiloxane comprising one or multiple components, represented by general formula MaiMHbiDCiDHdTeiTH fiQgi, having a number average molecular weight (Mw) in the range of 300 to 15,000, and having at least 2 silicon-bonded hydrogen atoms on average in a single molecule
(B) An organopolysiloxane comprising one or multiple components, represented by general formula MajMVlbiDciDVldjTejTVlfjQgj, having a number average molecular weight (Mw) in the range of 300 to 100,000, and having at least 2 alkenyl groups on average in a single molecule Within the aforementioned general formulae, M represents R3Si01 2; D represents R2Si02/2; T represents RSi03/2; and Q is the siloxane unit represented by Si04/2; R is a monovalent organic group not having an aliphatic carbon-carbon double bond; MH, DH, and TH are siloxane units in which one of the R groups of the siloxane units represented by M, D, and T, respectively, is replaced by a silicon atom-bonded hydrogen atom; MV|, DV|, and TV| are siloxane units in which one of the R groups of the siloxane units represented by M, D, and T, respectively, is replaced by an alkenyl group of 2 to 20 carbon atoms; a is an average number per single molecule; b is an average number per single molecule; c is an average number per single molecule; d is an average number per single molecule; e is an average number per single molecule; f is an average number per single molecule; and g is an average number per single molecule; i represents the i-th component in the component (A); and j represents the j-th component in the component (B).
The aforementioned number of crosslink points per unit weight is calculated using the below listed values of the indices defined by each of the formulae for (i) the index of probability of inter terminal group reaction, (ii) the index of number of crosslink points of the reaction composition,
(iii) the index of raw material mole count in the reaction composition, and (iv) the index of molecular weight of the reaction composition: (Number of cross link points per unit weight)
(The index of number of cross Sink points of the reaction composition}
~ (The index of raw materia! mole (The index of molecular weight
count in the reaction composition) x of the reaction composition)
Here, the formulae defining each of the aforementioned indices are listed below:
(i) The index of probability of inter terminal group reaction is represented by the following formula.
(The index of pro
Figure imgf000022_0001
(ii) The index of number of crosslink points of the reaction composition is represented by the below formula based on the aforementioned index of probability of inter terminal group reaction).
(The index of number of cross link points of the reaction composition)
(The index of probability of inter terminal group reaction)
Figure imgf000022_0003
However, in the calculation of the index of the number of crosslink points of the reaction composition, a component in which the value of (a + c)/(b + d + e + f + g) representing the average number of organosiloxane units between reactive groups in the molecular chain is less than 3 is treated as acting as a single crosslink point, and for such a component, the calculation is performed by (b + d) = 0, and (e + f + g) = 1.
(iii) The index of raw material mole count in the reaction composition is represented by the following formula.
{The index of raw materia! mole count in the reaction composition) ÷ f A-
Figure imgf000022_0004
(iv) The index of molecular weight of the reaction composition is represented by the following
(The index of molecuiar weight in the reaction composition)
Figure imgf000023_0001
Here, a, is the value of the blending amount a™ (an amount by weight) of the i-th component of the component (A) divided by the ratio (γ = H(moles)/Vi(moles)) of the number H (moles) of silicon-bonded hydrogen atoms contained in the component (A) and the number Vi (moles) of alkenyl groups contained in the component (B), i.e. a, = aw/ γ; ft represents the blending amount (an amount by weight) of the j-th component of the component (B); Mwi represents number average molecular weight of the i-th component of the component (A); and Mwj represents number average molecular weight of the j-th component of the component (B).
[0065]
[Characteristic 5] Molecular Weight between Crosslink Points after the Curing Reaction
Furthermore, the molecular weight between crosslink points of the reactive polysiloxane after the curing reaction is defined by the below formulae based on the number average molecular weight of each of the components of the (A) component and (B) component, the values of a, to g, and ¾ to gj of the below general formulae, and the concentrations of each component in the composition, where this molecular weight between crosslink points of the reactive polysiloxane after the curing reaction is preferably in the range of 100,000 to 2,000,000, and further preferably is in the range of 200,000 to 2,000,000:
(A) is an organohydrogenpolysiloxane comprising one or multiple components, represented by general formula MaiMHbiDCiDH diTeiTH 1iQgi, having a number average molecular weight (Mw) in the range of 300 to 15,000, and having at least 2 silicon-bonded hydrogen atoms on average in a single molecule.
(B) is an organopolysiloxane comprising one or multiple components, represented by general formula
Figure imgf000023_0002
having a number average molecular weight (Mw) in the range of 300 to 100,000, and having at least 2 alkenyl groups on average in a single molecule.
(C) is a catalyst for addition reaction between the aforementioned component (A) and component (B).
Within the aforementioned general formulae, M represents R3Si01 2; D represents R2Si02/2; T represents RSi03/2; and Q is the siloxane unit represented by Si04/2; R is a monovalent organic group not having an aliphatic carbon-carbon double bond; MH, DH, and TH are siloxane units in which one of the R groups of the siloxane units represented by M, D, and T, respectively, is replaced by a silicon atom-bonded hydrogen atom; MV|, DV|, and TV| are siloxane units in which one of the R groups of the siloxane units represented by M, D, and T, respectively, is replaced by an alkenyl group of 2 to 20 carbon atoms; a is an average number per single molecule; b is an average number per single molecule; c is an average number per single molecule; d is an average number per single molecule; e is an average number per single molecule; f is an average number per single molecule; and g is an average number per single molecule; i represents the i-th component in the component (A); and j represents the j-th component in the component (B).
The aforementioned molecular weight between crosslink points is based on the index values calculated based on the below represented calculation formulae for (i) the index of probability of inter terminal group reaction, (ϋ') the index of organosiloxane chain count of the reaction composition, (iii) the index of raw material mole count in the reaction composition, and (iv) the index of molecular weight of the reaction composition:
(Molecular weight between cross link points)
(The index of moSecylar weight (The index of raw material rrto!e
of the reaction composition) X count in the reaction composition)
(The index of organosiloxane chain count of the reaction composition)
Here, the formulae defining each of the aforementioned indices are listed below:
(i) The index of probability of inter terminal group reaction is represented by the following formula.
(The Index of
Figure imgf000024_0001
(ϋ') The index of organosiloxane chain count of the reaction composition is represented by the following formula.
(The index of )
ction)
Figure imgf000025_0001
However, in the calculation of the index of number of crosslink points of the reaction composition, a component for which the value of (a + c)/(b + d + e + f + g) representing average number of organosiloxane units between reactive groups in the molecular chain is less than 3 is taken to act as a single crosslink point, and calculation for such a component assumes (d+2e+2f+3g+1 )=0.
(iii) The index of raw material mole count in the reaction composition is represented by the following formula.
;·· r
{The index of raw material mole count in the reaction composition) ~ )™~ -t
(iv) The index of molecular weight of the reaction composition is represented by the following formula.
(The index of mo!ecu!ar weight in the reaction composition)
Figure imgf000025_0002
In the aforementioned formulae, a, is the value of the blending amount a™ (an amount by weight) of the i-th component of the component (A) divided by the ratio (γ = H(moles)/Vi(moles)) of the number H (moles) of silicon-bonded hydrogen atoms contained in the component (A) and the number Vi (moles) of alkenyl groups contained in the component (B), i.e. a, = a™/ γ; ft represents the blending amount (an amount by weight) of the j-th component of the component (B); Mwi represents number average molecular weight of the i-th component of the component (A); and MWj represents number average molecular weight of the j-th component of the component (B). The aforementioned number average molecular weight (Mw) is a value determined by measurement by nuclear magnetic resonance (NMR).
[0066] By molecular design, so as to adjust the number of crosslink points per unit weight and the molecular weight between crosslink points after curing of the organopolysiloxane to within certain ranges based on the formulae described in this patent specification, it is possible to perform adjustment such that the obtained silicone elastomer cured article has electrical characteristics and mechanical properties suitable for a member of a transducer. By such molecular design, it is possible to obtain an addition-curable organopolysiloxane composition for the production of a silicone elastomer cured article and silicone elastomer suitable as materials for use as a dielectric material having excellent characteristics, a dielectric material for a transducer member, particularly a dielectric elastomer, and further particularly a member for a transducer.
[0067]
[Curing Agent (C)]
The curable organopolysiloxane composition for transducers of the present invention comprises a curing agent (C) as a necessary ingredient.
The component (C) is preferably a generally known hydrosilylation reaction catalyst. No particular limitation is placed on the component (C) used in the present invention, as long as the component (C) is a substance capable of promoting the hydrosilylation reaction. This component (C) is exemplified by platinum based catalysts, rhodium based catalysts, and palladium based catalysts. Due to high catalyst activity, particularly platinum family element catalysts and platinum family element compound catalysts are cited as the component (C). Without particular limitation, platinum based catalysts are exemplified by platinum fine powder, platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid; olefin-platinum complexes, platinum-carbonyl complexes such as platinum bis-acetoacetate), platinum bis(acetylacetate), or the like; chloroplatinic acid-alkenyl siloxane complexes such as chloroplatinic acid-divinyltetramethyldisiloxane complex, chloroplatinic
acid-vinyltetramethylcyclotetrasiloxane complex, or the like; platinum-alkenylsiloxane complexes such as platinum-divinyltetramethyldisiloxane complex,
platinum-tetravinyltetramethylcyclotetrasiloxane complex, or the like; and complexes between chloroplatinic acid and acetylene alcohols. Due to high catalyst activity with respect to hydrosilylation reactions, recommended examples of the component (C) are
platinum-alkenylsiloxane complexes, and particularly platinum
1 ,3— divinyl— 1 ,1 ,3,3-tetramethyldisiloxane complexes.
[0068]
Moreover, for further improvement of stability of the platinum-alkenylsiloxane complex, these platinum-alkenylsiloxane complexes may be dissolved in an organosiloxane oligomer such as alkenylsiloxane oligomers of 1 ,3— divinyl— 1 ,1 ,3,3-tetramethyldisiloxane,
1 ,3— diallyl— 1 ,1 ,3,3-tetramethyldisiloxane, 1 ,3— divinyl— 1 ,3-dimethyl-1 ,3-diphenyldisiloxane, 1 ,3— divinyl— 1 ,1 ,3,3-tetraphenyldisiloxane,
1 ,3,5,7-tetramethyl-1 ,3,5,7-tetravinylcyclotetrasiloxane, or the like; or dimethylsiloxane oligomers; or the like. In particular the use of a platinum-alkenylsiloxane complex dissolved in an alkenylsiloxane oligomer is preferred.
[0069]
The utilized amount of the component (C) may be any amount capable of promoting the addition reaction of the polysiloxane component of the present composition, without particular limitation. Relative to the entire weight of the polysiloxane component, the concentration of a platinum family metal element contained in the component (C) (e.g. platinum) is normally in the range of 0.01 to 500 ppm, preferably is in the range of 0.1 to 100 ppm, and further preferably is in the range of 0.1 to 50 ppm.
[0070]
[Dielectric Inorganic Fine Particles (D)]
The curable organopolysiloxane composition for transducers of the present invention is characterized as containing, as necessary ingredients, the curable organopolysiloxane composition having the aforementioned characteristics, a curing agent, and (D) dielectric particles having a specific dielectric constant at 1 kHz of greater than or equal to 10 at room temperature. By supporting the dielectric inorganic fine particles in the cured article comprising the aforementioned curable organopolysiloxane, the physical characteristics and electrical characteristics needed for a transducer are both satisfied.
The dielectric inorganic fine particles, for example, may be selected from among metal oxides (D1 ) represented by the below listed Formula (D1 ) (sometimes abbreviated hereinafter as the "metal oxide (D1 )"):
Ma naMb nbOnc (D1 )
(in the formula,
Ma is a family 2 metal of the periodic table;
Mb is a family 4 metal of the periodic table;
na is a number ranging from 0.9 to 1.1 ;
nb is a number ranging from 0.9 to 1.1 ; and
nc is a number ranging from 2.8 to 3.2).
[0071 ]
Preferred examples of the family 2 periodic table metal Ma in the metal oxide (D1 ) include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Titanium (Ti) is cited as a preferred example of a family 4 periodic table metal Mb. In the particles of metal oxides represented by the Formula (X1 ), Ma and Mb may each be a single element, or may be 2 or more elements. [0072]
Specific examples of the metal oxide (D1 ) include barium titanate, calcium titanate, and strontium titanate.
[0073]
Moreover, the dielectric inorganic fine particles, for example, may be selected from among metal oxides (hereinafter, can be referred to as "metal oxide (D2)") represented by:
Ma naMb nbOnc (D2)
(in the formula,
Ma is a family 2 metal of the periodic table;
Mb is a family 5 metal of the periodic table;
na is a number ranging from 0.9 to 1.1 ;
nb' is a number ranging from 0.9 to 1 .1 ; and
nc is a number ranging from 2.8 to 3.2).
[0074]
Preferred examples of the family 2 periodic table metal Ma in the metal oxide (D2) include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Preferred examples of the family 5 periodic table metal element Mb include tin (Sn), antimony (Sb), zirconium (Zr), and indium (In). In the particles of the metal oxide represented by the formula (X2), Ma and Mb may each be a single type of element, or may be 2 or more elements.
[0075]
Specific examples of the metal oxide (D2) include magnesium stannate, calcium stannate, strontium stannate, barium stannate, magnesium antimonate, calcium antimonate, strontium antimonate, barium antimonate, magnesium zirconate, calcium zirconate, strontium zirconate, barium zirconate, magnesium indate, calcium indate, strontium indate, barium indate, or the like.
[0076]
Further, in combination with such metal oxide particles, it is permissible to use particles of other metal oxides such as lead titanate zirconate, zinc titanate, lead titanate, titanium oxide, or the like (particularly titanium oxide composite oxides other than those previously listed). Moreover, solid solutions comprising metal elements different from these examples may be used as the dielectric inorganic fine particles (D). In this case, the other metal elements are exemplified by La (lanthanum), Bi (bismuth), Nd (neodymium), Pr (praseodymium), or the like.
[0077]
Among such inorganic fine particles, preferred examples of the dielectric inorganic fine particles
(D) include one or more types of inorganic fine particles selected from the group consisting of titanium oxide, barium titanate, strontium titanate, lead titanate zirconate, and barium titanate, and composite metal oxides in which the barium and titanium positions of barium titanate are partially replaced by an alkaline earth metal, such as calcium or strontium; zirconium ; or rare earth metal, such as yttrium, neodymium, samarium, or dysprosium. Titanium oxide, barium titanate, strontium titanate, and composite metal oxide in which the barium positions of barium titanate and barium zirconate are partially replaced by calcium are more preferred, and titanium oxide and barium titanate are most preferred.
[0078]
No particular limitation is placed on the morphology of the dielectric inorganic fine particles (D), and any morphology may be used, such as spherical, tabular, needle-like, fibrous, or the like. No particular limitation is placed on particle diameter of the inorganic fine particles, and if the spherical fine particles are measured by the laser diffraction method, for example, the volume average particle diameter may be in the range of 0.01 to 1 .0 μιη, for example. From the standpoints of molding-processing ability and film forming ability, the average particle diameter is preferably in the range of 0.1 to 5 μιη. If the inorganic fine particles are anisotropic fine particles in which the morphology is tabular, needle-like, fibrous, or the like, although no limitation is placed on the aspect ratio of such fine particles, the aspect ratio may normally be greater than or equal to 5.
[0079]
No particular limitation is placed on the particle size distribution of the dielectric inorganic fine particles, and the dielectric inorganic fine particles may be mono-dispersed, or alternatively, it is possible to produce a distribution in the particle diameters so as to improve mechanical strength by filling at higher density by lowering the void fraction between fine particles. As a measure of the particle diameter distribution, the ratio (D90/D10) of the particle diameter at 90% cumulative area (D90) over the particle diameter at 10% cumulative area (D10) of the cumulative particle diameter distribution curve measured by the laser light diffraction method is preferably greater than or equal to 2. Moreover, no limitation is placed on the particle diameter distribution shape (relationship between particle diameter and particle concentration), It is possible to have a so-called plateau shaped distribution, or a particle diameter distribution that is multi-modal, i.e. bimodal (i.e. Having two hill-shaped distributions), tri-modal, or the like.
[0080]
In order to make particle size distributions such as those described above for the dielectric inorganic fine particles used in the present invention, methods may be adopted, for example, such as combined use of two or more types of fine particles having different average diameters or particle size distributions, blending of particles of particle diameter fractions obtained by sieving or the like to produce a desired particle size distribution, or the like.
[0081 ]
Furthermore, these dielectric inorganic fine particles may be treated using various types of the below described surface treatment agents.
[0082]
In consideration of mechanical characteristics and dielectric characteristics of the obtained cured article, the blended amount (loading fraction) of the dielectric inorganic fine particles in the curable organopolysiloxane composition for transducers of the present invention, relative to the entire volume of the composition, may be greater than or equal to 10%, preferably is greater than or equal to 15%, and further preferably is greater than or equal to 20%. Moreover, this blended amount relative to the total volume of the composition is preferably less than or equal to 80%, and further preferably is less than or equal to 70%.
[0083]
As a preferred embodiment of the curable organopolysiloxane composition for transducers of the present invention, a composition is cited that comprises as necessary ingredients: (A1 ) at least one type of organohydrogenpolysiloxane having silicon atom-bonded hydrogen atoms at both molecular terminals and having a hydrogen atom weight content of 0.01 to 1 .0% by weight, (A2) at least one type of organohydrogenpolysiloxane having at least 3 silicon atom-bonded hydrogen atoms in a single molecule and having a hydrogen atom weight content of 0.03 to 2.0% by weight, (B) at least one type of organopolysiloxane having at least 2 alkenyl groups in a single molecule and having an alkenyl group weight content of 0.05 to 0.5% by weight, (C1 ) a hydrosilylation reaction catalyst, and (D) dielectric inorganic fine particles having a specific dielectric constant at 1 kHz of greater than or equal to 10 at room temperature.
Here, (A1 ) is preferably a dimethylhydrogensiloxy group-doubly molecular chain terminated polydimethylsiloxane. Preferred examples of (A2) include trimethylsiloxy group-doubly molecular chain terminated dimethylsiloxane-methylhydrogensiloxane copolymers and dimethylhydrogensiloxy group-doubly molecular chain terminated
dimethylsiloxane-methylhydrogensiloxane copolymers. On the other hand, the (B) component is exemplified by dimethylvinylsiloxy group-doubly molecular chain terminated
polydimethylsiloxanes. In order to further optimize transducer material characteristics such as mechanical characteristics, dielectric characteristics, heat resistance, or the like, part of the methyl groups of the polymers may be replaced by an ethyl group, propyl group, butyl group, hexyl group, or phenyl group.
No particular limitation is placed on molecular weights of (A1 ), (A2), and (B), as long as the weight content of the hydrogen atoms and the weight content of the alkenyl groups are in the aforementioned ranges. However, the number of siloxane units is preferably 5 to 1 ,500.
[0084]
The curable organopolysiloxane composition of the present invention is a curable
organopolysiloxane composition used for transducers, and the curable organopolysiloxane composition of the present invention may be further provided with the below described characteristics.
[0085]
[Other Inorganic Particles (E)]
The curable organopolysiloxane composition of the present invention may further comprise one or more types of inorganic particles (E) selected from the group consisting of electrically conductive inorganic particles, insulating-inorganic particles, and reinforcing-inorganic particles.
[0086]
No particular limitation is placed on the utilized electrically conductive inorganic particles as long as the electrically conductive inorganic particles impart electrical conductivity, and it is possible to use any morphology, such as particle-shaped, flake-shaped, and fibrous (including whiskers). Specific examples of electrically conductive inorganic particles include: electrically conductive carbon such as electrically conductive carbon black, graphite, monolayer carbon nanotubes, double layer carbon nanotubes, multilayer carbon nanotubes, fullerenes, fullerene-encapsulated metals, carbon nanofibers, gas phase-grown mono-length carbon (VGCF), carbon micro-coils, or the like; and metal powders such as platinum, gold, silver, copper, nickel, tin, zinc, iron, aluminum, or the like powders; as well coated pigments such as antimony-doped tin oxide, phosphorous-doped tin oxide, needle-shaped titanium oxide surface-treated using tin/antimony oxide, tin oxide, indium oxide, antimony oxide, zinc antimonate, carbon, and graphite or carbon whiskers surface-treated by tin oxide or the like; pigments coated by at least one type of electrically conductive oxide such as tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), phosphorous-doped tin oxide, and phosphorous-doped nickel oxide; pigments having electrical conductivity and containing tin oxide and phosphorous in the surface of titanium oxide particles; these electrically conductive inorganic particles being optionally surface-treated using various types of the below described surface treatment agents. Such electrically conductive inorganic particles may be used as one type or as a combination of 2 or more types.
[0087]
Furthermore, the electrically conductive inorganic fine particles may be fibers such as glass fibers, silica alumina fibers, alumina fibers, carbon fibers, or the like, or needle-like reinforcing materials such as aluminum borate whiskers, potassium titanate whiskers, or the like; or an inorganic filler material such as glass beads, talc, mica, graphite, wollastonite, dolomite, or the like, that have been surface coated by an electrically conductive substance such as a metal or the like.
[0088]
By blending the electrically conductive inorganic particles into the composition, it is possible to increase the specific dielectric constant of the polysiloxane cured article. The blended amount of such electrically conductive inorganic particles relative to the curable organopolysiloxane composition is preferably in the range of 0.01 to 10% by weight, and further preferably is in the range of 0.05 to 5% by weight. When the blended amount departs from the aforementioned preferred range, the effect of blending is not obtained, or there may be a lowering of the dielectric breakdown strength of the cured article.
[0089]
The insulating-inorganic particles utilized in the present invention may be any generally known insulating inorganic material. That is to say, particles of any inorganic material having a volume resistance value of 1010 to 1019 Ohm-cm may be used without restriction, and any morphology may be used, such as particulate, flake-like, and fibrous (including whiskers). Preferred specific examples include spherical particle, tabular particles, and fibers of ceramics; particles of metal silicates such as alumina, mica and talc or the like; and quartz, glass, or the like.
Moreover, such insulating-inorganic particles may be surface-treated using the various types of below described surface treatment agents. Such electrically conductive inorganic particles may be used as one type or as a combination of 2 or more types.
[0090]
By blending the insulating-inorganic particles into the composition, it becomes possible to increase the mechanical strength and dielectric breakdown strength of the polysiloxane cured article, and the specific dielectric constant may sometimes be observed to increase. The blended amount of these insulating-inorganic particles, relative to the curable
organopolysiloxane composition, is preferably in the range of 0.1 to 20% by weight, and further preferably is in the range of 0.1 to 5% by weight. When the blended amount of the
insulating-inorganic particles deviates from the aforementioned preferred range, the effect of blending is not obtained, or there may be a lowering of the mechanical strength of the cured article.
[0091 ]
The reinforcing-inorganic particles used in the present invention are exemplified by fumed silica, wet type silica, ground silica, calcium carbonate, diatomaceous earth, finely ground quartz, various types of non-alumina metal oxide powders, glass fibers, carbon fibers, or the like.
Moreover, such reinforcing inorganic particle may be used after treatment using the below described various types of surface treatment agents. Here, although no limitation is placed on the particle diameter of the reinforcing-inorganic particles, the specific surface area is preferably greater than or equal to 50 m2/g and less than or equal to 300 m2/g from the standpoint of improvement of mechanical strength, fumed silica is particularly preferred. Further, from the standpoint of improvement of dispersability, the fumed silica is preferably surface-treated using the below described silica coupling agent. However, when the (A) curable organopolysiloxane composition is an addition-curable type organopolysiloxane composition, fumed silica surface-treated using silazane is not used as the reinforcing-inorganic particles. These reinforcing-inorganic particles may be used as a single type, or may be used as a combination of 2 or more types.
[0092]
By blending the reinforcing-inorganic particles into the composition, it becomes possible to increase mechanical strength and dielectric breakdown strength of the polysiloxane cured article. The blended amount of these reinforcing-inorganic particles relative to the curable
organopolysiloxane composition is preferably in the range of 0.1 to 30% by weight, and further preferably in the range of 0.1 to 10% by weight. When the blended amount deviates from the aforementioned preferred range, the effect of blending and the inorganic particles is not obtained or molding processability of the curable organopolysiloxane composition may decrease.
[0093]
The curable organopolysiloxane composition of the present invention may further comprise thermally conductive inorganic particles. The thermally conductive inorganic particles are exemplified by metal oxide particles such as magnesium oxide, zinc oxide, nickel oxide, vanadium oxide, copper oxide, iron oxide, silver oxide, or the like; and inorganic compound particles such as aluminum nitride, boron nitride, silicon carbide, silicon nitride, boron carbide, titanium carbide, diamond, diamond-like carbon, or the like. Zinc oxide, boron nitride, silicon carbide, and silicon nitride are preferred. By blending these thermally conductive inorganic particles into the composition, it becomes possible to increase the thermal conductivity of the polysiloxane cured article. Relative to the curable organopolysiloxane composition, the blended amount of these reinforcing-inorganic particles is preferably in the range of 0.1 to 30% by weight.
[0094]
[Surface Treatment of the Inorganic Particles or the Like]
However, part or the entire quantity of the filler, specifically, the aforementioned dielectric inorganic fine particles (D) and at least one type of the inorganic particles (E) used in the curable organopolysiloxane composition of the present invention may undergo surface treatment by use of at least one type of surface treatment agent. No particular limitation is placed on the type of surface treatment, and such surface treatment is exemplified by hydrophilization treatment and hydrophobizing treatment. Hydrophobization treatment is preferred. When inorganic particles are used that have undergone hydrophobizing treatment, it is possible to increase the degree of loading of the inorganic particles in the organopolysiloxane composition. Moreover, increase of viscosity of the composition is suppressed, and molding processability is improved.
[0095]
The aforementioned surface treatment may be performed by treatment (or coating treatment) of the inorganic particles using a surface treatment agent. The surface treatment agent used for hydrophobizing is exemplified by at least one type of surface treatment agent selected from the group consisting of organic titanium compounds, organic silicon compounds, organic zirconium compounds, organic aluminum compounds, and organic phosphorous compounds. The surface treatment agent may be used as a single type or may be used as a combination of 2 or more types.
[0096]
The organic titanium compound is exemplified by coupling agents such as alkoxy titanium, titanium chelates, titanium acrylates, or the like. Preferred coupling agents among such compounds are exemplified by alkoxy titanium compounds such as tetraisopropyl titanate or the like, and titanium chelates such as tetraisopropyl bis(dioctylphosphate) titanate or the like.
[0097]
The organic silicon compound is exemplified by low molecular weight organic silicon compounds such as silanes, silazanes, siloxanes, or the like; and organic silicon polymers or oligomers such as polysiloxanes, polycarbosiloxanes, or the like. Preferred silanes are exemplified by so-called silane coupling agents. Representative examples of such silane coupling agents include alkyltrialkoxysilanes (such as methyltrimethoxysilane, vinyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, or the like), organic functional group-containing trialkoxysilane (such as glycidoxypropyltrimethoxysilane, epoxycyclohexylethyltrimethoxysilane, methacryloxypropyltrimethoxysilane, aminopropyltrimethoxysilane, or the like). Preferred siloxanes and polysiloxanes include hexamethyldisiloxane, 1 ,3-dihexyl-tetramethyldisiloxane, trialkoxysilyl single-terminated polydimethylsiloxane, trialkoxysilyl single-terminated dimethylvinyl single-terminated polydimethylsiloxane, trialkoxysilyl single terminated organic functional group single-terminated polydimethylsiloxane, trialkoxysilyl doubly terminated polydimethylsiloxane, organic functional group doubly-terminated polydimethylsiloxane, or the like. When a siloxane is used, the number n of siloxane bonds is preferably in the range of 2 to 150. Preferred silazanes are exemplified by hexamethyldisilazane,
1 ,3-dihexyl-tetramethyldisilazane, or the like. Preferred polycarbosiloxanes are exemplified by polymers that have Si-C-C-Si bonds in the polymer main chain.
[0098]
The organic zirconium compound is exemplified by alkoxy zirconium compounds such as tetraisopropoxy zirconium or the like and zirconium chelates.
[0099]
The organic aluminum compound is exemplified by alkoxy aluminum and aluminum chelates.
[0100]
The organic phosphorous compound is exemplified by phosphite esters, phosphate esters, and phosphorous acid chelates.
[0101 ]
Among these surface treatment agents, organic silicon compounds are preferred. Among such organic silicon compounds, silanes, siloxanes, and polysiloxanes are preferred. As described previously, the use of alkyltrialkoxysilanes and trialkoxysilyl single-terminated
polydimethylsiloxanes is most preferred.
[0102]
The ratio of the surface treatment agent to the total amount of the aforementioned inorganic particles is preferably in the range of greater than or equal to 0.1 % by weight and less than or equal to 10% by weight, and this range is further preferably greater than or equal to 0.3% by weight and less than or equal to 5% by weight. Furthermore, the treatment concentration is the ratio (weight ratio) of the fed inorganic particles to the fed treatment agent, and the excess treatment agent is preferably removed after treatment.
[0103]
[Additive (F)]
The curable organopolysiloxane composition of the present invention may further comprise an additive (F) for improvement of mold releasability or insulation breakdown characteristics. The electrically active silicone elastomer sheet obtained by curing this polysiloxane composition as a thin sheet may be used with advantage as an electrically active film (dielectric layer or electrode layer) constituting a transducer. However, when mold releasability of the silicone elastomer sheet is poor during molding of the thin film, and particularly when a dielectric film is produced at high speed, the dielectric film may be damaged due to demolding. However, the curable organopolysiloxane composition for transducers of the present invention has excellent demolding characteristics, and thus the curable organopolysiloxane composition is
advantageous in that it is possible to improve speed of production of the film without damaging the film. This additive further improves these features of the curable organopolysiloxane composition of the present invention, and this additive may be used as a single type or as a combination of 2 or more types. On the other hand, an additive for improvement of insulation breakdown characteristics, as per the name of the additive, is used for improvement of dielectric breakdown strength of the silicone elastomer sheet.
[0104]
Demolding improvement additives (i.e. mold release agents) capable of use are exemplified by carboxylic acid type demolding agents, ester type demolding agents, ether type demolding agents, ketone type demolding agents, alcohol type demolding agents, or the like. Such demolding agents may be used alone as a single type or may be used as a combination of 2 or more types. Moreover, although the aforementioned demolding agents do not contain silicon atoms, it is also possible to use a demolding agent that contains silicon atoms, or it is possible to use a mixture of such demolding agents.
[0105]
The demolding agent that does not contain silicon atoms may be selected, for example, from the group consisting of saturated or unsaturated fatty carboxylic acids such as palmitic acid, stearic acid, or the like; alkali metal salts of such fatty carboxylic acids (such as sodium stearate, magnesium stearate, calcium stearate, or the like); esters of fatty carboxylic acids and alcohols (such as 2-ethylhexyl stearate, glycerin tristearate, pentaerythritol monostearate, or the like), aliphatic hydrocarbons (liquid paraffin, paraffin wax, or the like), ethers (distearyl ether or the like), ketones (distearyl ketone or the like), higher alcohols (2-hexadecyloctadecanol or the like), and mixtures of such compounds.
[0106]
The silicon atom-containing demolding agent is preferably a non-curable silicone type demolding agent. Specific examples of such silicone type demolding agents include non-organic modified silicone oils such as polydimethylsiloxane, polymethylphenylsiloxane, poly(dimethylsiloxane-methylphenylsiloxane) copolymers,
poly(dimethylsiloxane-methyl(3,3,3-trifluoropropyl)siloxane copolymers, or the like; and modified silicone oils such as amino-modified silicones, amino polyether-modified silicones, epoxy-modified silicones, carboxyl-modified silicones, polyoxyalkylene-modified silicones, or the like. Such silicon atom-containing demolding agents may have any structure, such as linear, partially-branched linear, or ring shaped. Moreover, no particular limitation is placed on the viscosity of such silicon oils at 25 °C. This viscosity is preferably in the range of 10 to 100,000 mPa-s, and further preferably is in the range of 50 to 10,000 mPa-s.
[0107]
Although no particular limitation is placed on the blended amount of the demolding improvement additive, relative to the total amount of the curable organopolysiloxane, this amount is preferably in the range of greater than or equal to 0.1% by weight and less than or equal to 30% by weight.
[0108]
On the other hand, the insulation breakdown characteristic improvement agent is preferably an electrical insulation improvement agent. The insulation breakdown characteristic improvement agent is exemplified by aluminum or magnesium hydroxides or salts, clay minerals, and mixtures of such. Specifically, the insulation breakdown characteristic improvement agent may be selected from the group consisting of aluminum silicate, aluminum sulfate, aluminum hydroxide, magnesium hydroxide, calcined clays, montmorillonite, hydrotalcite, talc, and mixtures of such agents. Moreover, as may be required, this insulation improvement agent may be
surface-treated by the aforementioned surface treatment method. [0109]
No particular limitation is placed on the blended amount of this insulation improvement agent. Relative to the total amount of the curable organopolysiloxane, this blended amount is preferably in the range of greater than or equal to 0.1% by weight and less than or equal to 30% by weight.
[0110]
The curable organopolysiloxane composition of the present invention may comprise another organopolysiloxanes that differs from the aforementioned reactive organopolysiloxane that that has dielectric functional groups.
[0111 ]
[Curing Mechanism]
In the same manner, the curable organopolysiloxane composition of the present invention may further comprise a compound that has highly dielectric functional groups and at least one group in the molecule capable of reacting by condensation curing reaction, addition curing reaction, peroxide curing reaction, or photo-curing reaction. This highly dielectric functional group is introduced to the obtained cured article (i.e. electrically active silicone elastomer) by the aforementioned curing reaction.
[0112]
[Introduction of the Highly Dielectric Functional Group]
For the curable organopolysiloxane composition of the present invention, part or the entire aforementioned reactive organopolysiloxane may be a reactive organopolysiloxane further having a highly dielectric functional group.
[0113]
If an electrically active silicone elastomer obtained by curing the curable organopolysiloxane composition for transducers of the present invention is used for a dielectric layer, specific dielectric constant of the dielectric layer is preferably high, and highly dielectric functional groups may be introduced in order to improve the specific dielectric constant of the elastomer.
[0114]
Specifically, dielectric properties may be increased for the curable organopolysiloxane composition and cured electrically active silicone elastomer obtained by curing the curable organopolysiloxane composition, by a method such as adding to the curable organopolysiloxane composition a component for imparting high dielectric properties, a method of introducing a highly dielectric group to the organopolysiloxane component constituting the curable
organopolysiloxane composition, or a combination of such methods. Such specific
embodiments and highly dielectric functional groups capable of introduction will be explained below.
[0115] In a first embodiment, the curable organopolysiloxane composition for transducers is formed from a curable organopolysiloxane composition that comprises an organic silicon compound that has a highly dielectric group. In this curable composition, part or the entire reactive
organopolysiloxane contained in the curable composition is a reactive organopolysiloxane further having a highly dielectric functional group, and the specific dielectric constant of the electrically active silicone elastomer obtained by curing is increased.
[0116]
In a second embodiment, an organic silicon compound having highly dielectric groups is added to the curable organopolysiloxane composition, and the mixture is cured to obtain an electrically active silicone elastomer that has an increased specific dielectric constant. An organic silicon compound having highly dielectric groups may be added separately from the component used for curing in this curable composition.
[0117]
In a third embodiment, an organic compound having highly dielectric groups and functional groups reactive with the reactive organopolysiloxane contained in the curable composition is added to the curable organopolysiloxane composition, thereby increasing specific dielectric constant of the electrically active silicone elastomer obtained by curing. As a result of formation of bonds between the organic compound and the organopolysiloxane due to the functional groups of the organic compound that are reactive with the reactive organopolysiloxane in this curable composition, highly dielectric groups are introduced into the electrically active silicone elastomer obtained by curing.
[0118]
In a fourth embodiment of the present invention, an organic compound miscible with the curable organopolysiloxane composition and having highly dielectric groups is added to the curable organopolysiloxane composition, and thus the specific dielectric constant of the electrically active silicone elastomer obtained by curing is increased. Due to miscibility between the organic compound and the organopolysiloxane in this curable composition, an organic compound having these highly dielectric groups is incorporated in the matrix of the electrically active silicone elastomer obtained by curing.
[0119]
No particular limitation is placed on the highly dielectric group in the present invention, and the highly dielectric group may be any group capable of increasing dielectric properties of the obtained cured article obtained by curing the curable organopolysiloxane composition of the present invention in comparison to the dielectric properties when the group is not contained. Without limitation, examples of the highly dielectric group used in the present invention are listed below. a) Halogen Atoms and Halogen Atom-containing Groups
No particular limitation is placed on the halogen atom, and the halogen atom is exemplified by the fluorine atom and chlorine atom. The halogen atom-containing group may be selected as an organic group having one or more atoms of one or more types selected from fluorine atom and chlorine atom, as exemplified by halogenated alkyl groups, halogenated aryl groups, and halogenated aryl alkyl groups. Specific examples of halogen-containing organic groups include the chloromethyl group, 3-chloropropyl group, 3,3,3— trifluoropropyl group, and perfluoroalkyl group, without limitation. By introduction of such groups, it is possible to anticipate also an improvement of demolding ability of the cured article of the present invention and the cured article obtained from the composition.
b) Nitrogen Atom-containing Groups
Nitrogen atom-containing groups are exemplified by the nitro group, cyano groups (e.g.
cyanopropyl group and cyanoethyl group), amido groups, imido groups, ureido group, thioureido group, and isocyanate group.
c) Oxygen Atom-containing Groups
The oxygen atom-containing group is exemplified by ether groups, carbonyl groups, and ester groups.
d) Heterocyclic Groups
The heterocyclic group is exemplified by an imidazole group, pyridine group, furan group, pyran group, thiophene group, phthalocyanine group, and complexes of such.
e) Boron-containing Groups
The boron-containing group is exemplified by borate ester groups and boric acid salt groups. f) Phosphorous-containing Groups
The phosphorous-containing group is exemplified by the phosphine group, phosphine oxide group, phosphonate ester group, phosphite ester group, and phosphate ester group.
g) Sulfur-containing Groups
The sulfur-containing group is exemplified by the thiol group, thioether group, sulfoxide group, sulfone group, thioketone group, sulfonate ester group, and sulfonamide group.
[0120]
[Other Optional Ingredients: Curing Retardants or the Like]
The curable organopolysiloxane composition for transducers of the present invention may comprise additives normally blended in organopolysiloxane compositions. As long as the object of the curable organopolysiloxane composition for transducers of the present invention is not impaired, it is possible to blend any additives, such as a curing retardant (curing suppression agent), flame retardant, heat resistance improvement agent, colorant, solvent, or the like. If the curable organopolysiloxane composition is an addition reaction curable type organopolysiloxane composition, the curing retardant (curing suppression agent) is exemplified by alkyne alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1 -hexyn-3-ol, 2-phenyl-3-butyn-2-ol, or the like; enyne compounds such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne, or the like; and benzotriazole; without limitation. The utilized concentration of the curing retardant (curing suppression agent), relative to the total composition (weight basis), is preferably in the range of 1 to 50,000 ppm.
[0121 ]
[Hybrid Type]
As long as the object of the present invention is not impaired, hybridization is possible by combining the curable organopolysiloxane composition for transducers of the present invention with a polymer other than the organopolysiloxane. By hybridization with a polymer having a higher dielectric constant than that of the organopolysiloxane with the organopolysiloxane, it may be possible to increase the dielectric constant of the composition of the present invention and the cured article obtained from the composition. Hybridization embraces the so-called polymer blending of the organopolysiloxane with a non-organopolysiloxane polymer, and forming a fused polymer by bonding together (i.e. so-called co-polymerization) the organopolysiloxane and the other polymer. This type of hybrid co-polymers may be available as an intermediate raw material of the curable organopolysiloxane composition for transducer use by a step of adding as said curable organopolysiloxane with the filler into a composition for kneading, and of kneading the composition using an extruder or kneading apparatus
[0122]
The curable organopolysiloxane composition of the present invention may be condensation curable, addition curable, peroxide curable, or photo-curable, although an addition curable ogranopolysiloxane composition is preferred. To this curable system may be further included the introduction of an organopolysiloxane molecule chain by the method of adding the aforementioned dielectric functional group to an acrylic group, methacrylic group, epoxy group, or thiol group. By use of this photo-curable part or electron beam-curable part, in addition to the addition curing reaction, it is possible to also use a photo-curing reaction or electron beam curing reaction. If such combined reactions are used, a compound known as a monomer and/or oligomer capable of curing by light or electron beam (such as (meth)acrylate esters and multi-functional (meth)acrylate compounds) may be further added to the aforementioned curable composition. Moreover, a so-called photosensitizer may be added.
[0123]
[Mechanical Properties]
When the dielectric silicone elastomer that is this member for transducers obtained by curing of the curable organopolysiloxane composition of the present invention is thermally molded to a sheet of 2.0 mm thickness, it is then possible to have the below listed mechanical properties as measured based on JIS K 6249. However, according to the application of this dielectric silicone elastomer and other required electrical characteristics, it is possible to use a dielectric silicone elastomer having mechanical properties outside these mechanical property ranges.
(1 ) Young's modulus (MPa) at room temperature may be set in the range of 0.1 to 10 MPa, and the particularly preferred range is 0.1 to 2.5 MPa.
(2) Tear strength (N/mm) at room temperature may be set greater than or equal to 1 N/mm, and particularly is in the range greater than or equal to 2 N/mm.
(3) Tear strength (MPa) at room temperature may be set greater than or equal to 1 MPa, and particularly preferably is in the range greater than or equal to 2 MPa.
(4) Elongation at break (%) may be set greater than or equal to 100%, and from the standpoint of displacement amount of the transducer, is particularly preferably in the range of 200 to 1 ,000%.
[0124]
[Dielectric Characteristics]
The dielectric silicone elastomer that is this member for transducers obtained by curing of the curable organopolysiloxane composition of the present invention has the below listed dielectric characteristics. In particular, one important characteristic of the present invention is that, in addition to attainment of mechanical characteristics, such as those described above, by the composition of the present invention, the composition displays an excellent specific dielectric constant in the low frequency region.
(1 ) When the curable organopolysiloxane composition is thermally molded into a sheet of 0.07 mm thickness, the dielectric breakdown strength (V/μιη) may be set greater than or equal to 20 V/μιη. Although the preferred dielectric breakdown strength will vary according to the application of the transducer, the dielectric breakdown strength is particularly preferably in the range greater than or equal to 30 V/μιη.
(2) When the curable organopolysiloxane composition is thermally molded to a sheet of 1 mm thickness, the specific dielectric constant measured at 1 MHz measurement frequency and 23 °C measurement temperature may be set greater than or equal to 3.0. Although the preferred specific dielectric constant will change according to the required form of the dielectric layer and the type of the transducer, a particularly preferred range of specific dielectric constant under the aforementioned measurement conditions is greater than or equal to 5.0.
[0125]
[Production Method]
The production method of the curable organopolysiloxane composition of the present invention is described in above. The curable organopolysiloxane composition is preferably produced by using a twin screw extruder having a free volume of at least 5,000 (LVh) to knead the reactive organopolysiloxane component, dielectric inorganic fine particles, and a surface treatment agent, the present invention may form the Master Batch etc. comprising a high concentration (e.g. at least 80% by weight) of filler. Then the other reactive organopolysiloxane components, curing catalyst, and other components are preferably added and kneaded to produce the curable organopolysiloxane composition.
[0126]
Dielectric inorganic fine particle are dispersed well and at high density in the curable
organopolysiloxane composition of the curable organopolysiloxane composition for transducers obtained by the aforementioned production method, and it is thus possible to produce a member for transducers that has good electrical characteristics and mechanical characteristics.
Moreover, it is possible to obtain a uniform film-like cured article during production of the member for transducers, the electrical characteristics and mechanical characteristics of the obtained film-like cured article are excellent, and handling ability is excellent for lamination or the like.
[0127]
In the aforementioned kneading process, no particular limitation is placed on the temperature during formation of a silicone rubber compound (master batch etc.) that does not contain a vulcanization agent (curing catalyst). However, this temperature is set in the range of 40 °C to 200 °C, and may be set in the range of 100°C to 180°C. In a continuous process using a twin screw extruder or the like, the residence time during treatment may be set to about 30 seconds to 5 minutes.
[0128]
[Use of Curable Organopolysiloxane Composition for Transducers of the Present Invention] Due to the dielectric characteristics and mechanical characteristics of the electrically active silicone elastomer obtained by curing or semi-curing of the curable organopolysiloxane composition of the present invention, use is possible with particular advantage as a member for transducers selected from the group consisting of artificial muscles, actuators, sensors, and electricity generating elements. Specifically, after molding the curable organopolysiloxane composition into a sheet-like or film-like shape, the member may generally be cured by heating, irradiation by a high energy beam, or the like. Although no particular limitation is placed on the method for molding the curable organopolysiloxane composition into a film-like shape, the method is exemplified by a method of forming a coating film by coating of the curable organopolysiloxane composition on a substrate using previously widely known coating methods, a method of molding by passing the curable organopolysiloxane composition through an extruder equipped with a slot of the desired shape, or the like.
[0129] [Elastomer Film and Lamination]
Thickness of this type of film-like curable organopolysiloxane composition may be set in the range of 0.1 μιη to 5,000 μιη, for example. Depending on the aforementioned coating method and the absence or presence of a volatile solvent, thickness of the obtained cured article may be made thinner than thickness at the time of application of the composition.
[0130]
After production of the film-like curable organopolysiloxane composition by the aforementioned method, thermal curing, room temperature curing or curing by high energy beam irradiation may be performed, while optionally applying an electrical field or magnetic field in a target orientation direction for the dielectric inorganic fine particles, or after orienting of the filler by application of a magnetic field or electrical field for a fixed time period. Although no particular limitation is placed on each curing operation or the conditions during each curing operation, if the curable organopolysiloxane composition is an addition type curable organopolysiloxane composition, curing is preferably performed in the temperature range of 90 °C to 180°C by retention in this temperature range for 30 seconds to 30 minutes.
[0131 ]
No particular limitation is placed on the silicone elastomer for transducers, and this thickness may be 1 to 2,000 μιη, for example. The silicone elastomer for transducers of the present invention may be stacked as one layer or 2 or more layers. Furthermore, an electrode layer may be provided at both tips of the dielectric elastomer layer, and a configuration may be used in which the transducer itself is composed of multiple stacked electrode layers and the dielectric elastomer layers. Thickness of the silicone elastomer for transducers per single layer for such a configuration may be 0.1 μιη to 1 ,000 μιη. If such layers are stacked as at least 2 layers, the thickness per single layer may be 0.2 μιη to 2,000 μιη.
[0132]
Although no particular limitation is placed on the molding method of the two or more silicon elastomer cured layers stacked in the aforementioned manner, a method may be used such as:
(1 ) coating the curable organopolysiloxane composition on the substrate, during the coating, obtaining a cured silicone elastomer layer, and then further applying the curable
organopolysiloxane composition on the same cured layer to repeatedly coat and cure to stack layers; (2) coating the curable organopolysiloxane composition in a stacked manner on the substrate in an uncured or semi-cured state, and curing the entire curable organopolysiloxane compositions that have been coated in a stacked manner; or a method that combines the (1 ) and
(2) methods.
[0133]
For example, the curable organopolysiloxane composition may be applied on the substrate by die coating, may be cured, 2 or more such silicone elastomer cured layers may be formed by stacking, and the silicon elastomer cured layers may be attached to the electrode layer for manufacture in the present application invention. For this configuration, the 2 or more stacked silicon elastomer cured layers are preferably dielectric layers, and the electrode is preferably an electrically conductive layer.
[0134]
High speed coating is possible by die coating, and this coating method is highly productive. The transducer having the multilayered configuration of the present invention, after coating of a single layer containing the organopolysiloxane composition, may be produced by coating a layer that comprises a different organopolysiloxane composition. Moreover, production is possible by simultaneously coating multiple layers containing each organopolysiloxane composition.
[0135]
The thin film-like silicone elastomer that is the member for transducers may be obtained by coating the aforementioned curable organopolysiloxane composition on the substrate, and then curing the assembly at room temperature and by heating, or by curing using high energy beam irradiation such as ultraviolet radiation or the like. Moreover, when the thin film-like dielectric silicone elastomer is stacked, uncured curable organopolysiloxane composition may be applied on the cured layer and then cured sequentially, or the uncured curable organopolysiloxane composition may be stacked in layers, and then the layers may be cured simultaneously.
[0136]
The aforementioned thin film-like silicone elastomer is particularly useful as a dielectric layer for a transducer. It is possible to form a transducer by arrangement of electrode layers at both ends of the thin film-like silicone elastomer. Furthermore, by blending electrically conductive inorganic particles into the curable organopolysiloxane composition of the present invention, it is possible to provide functionality as an electrode layer. Furthermore, the "electrode layer" in the patent specification of the present invention is sometimes simply referred to as the "electrode." [0137]
One embodiment of the aforementioned member for transducers is sheet-like or film-like. Film thickness is generally 1 μιη to 2,000 μιη, and the film may have a structure that is a single layer, two or more layers, or a further number of stacked layers. Moreover, as may be desired, the stacked electrically active silicone elastomer layers, when used as dielectric layers, may be used with a film thickness of 5 μιη to 10,000 μιη, or such layers may be stacked to obtain greater thickness.
[0138]
The thin film-like silicone elastomer layer that is this member for transducers may be formed by stacking the same thin film-like silicone elastomer, or thin film-like silicone elastomers of 2 or more different physical characteristics or pre-curing compositions may be stacked to form this member for transducers. Moreover, the function of the thin film-like silicone elastomer layer may be a dielectric layer or an electrode layer. In particular, in a preferred member for a transducer, thickness of the dielectric layer is 1 to 1 ,000 μιη, and thickness of the electrode layer is 0.05 μιη to 100 μιη.
[0139]
The transducer of the present invention is characterized as having this member for transducers produced by curing of the curable organopolysiloxane composition for transducers of the present invention, and the transducer of the present invention may have a structure that particularly comprises a highly stacked layer structure (i.e. 2 or more dielectric layers). The transducer of the present invention further may have a structure that comprises 3 or more dielectric layers. The transducer that has this type of highly stacked structure is able to generate greater force by comprising multiple layers. Moreover, by stacking of layers, it is possible to obtain greater displacement than would be obtained by using a single layer.
[0140]
An electrode may be comprised at both ends of the dielectric layer for transducers of the present invention. The utilized electrode substance is exemplified by metals and alloys of metals such as gold, platinum, silver, palladium, copper, nickel, aluminum, titanium, zinc, zirconium, iron, cobalt, tin, lead, indium, chromium, molybdenum, manganese, or the like; metal oxides such as indium-tin compound oxide (ITO), antimony-tin compound oxide (ATO), ruthenium oxide, titanium oxide, zinc oxide, tin oxide, and the like; carbon materials such as carbon nanotubes, carbon nano-horns, carbon nanosheets, carbon fibers, carbon black, or the like; and electrically conductive resins such as poly(ethylene-3,4-dioxythiophene) (PEDOT), polyaniline, polypyrrole, or the like. Electrically conductive elastomers and electrically conductive resin having electrically conductive fillers dispersed in the resin can be used.
[0141 ]
The electrode may comprise one substance alone from among the aforementioned electrically conductive substances, or may comprise 2 or more such electrically conductive substances. If the electrode comprises 2 or more types of electrically conductive substances, one of the electrically conductive substances may function as the active substance, and the remaining electrically conductive substances may function as conductive materials for lowering resistance of the electrode.
[0142]
The total thickness of the dielectric layer for transducers of the present invention may be set in the range of 10 μιη to 2,000 μιη (2 mm), although this total thickness may be particularly set to a value greater than or equal to 200 μιη. In particular, thickness per single layer of the dielectric silicone elastomer layer forming the dielectric layer is preferably 0.1 to 500 μιη, and this thickness is particularly preferably 0.1 to 200 μιη. By stacking 2 or more layers of these thin silicone elastomer layers, it is possible to improve characteristics such as insulation breakdown voltage, dielectric constant, and displacement amount in comparison to the use of a single layer.
[0143]
The term "transducer" in the present invention is taken to mean an element, machine, or device for conversion of a certain type of energy to a separate type of energy. This transducer is exemplified by artificial muscles and actuators for conversion of electrical energy into mechanical energy; sensors and electricity generating elements for conversion of mechanical energy into electrical energy; speakers, microphones, and headphones for conversion of electrical energy into sound energy; fuel cells for conversion of chemical energy into electrical energy; and light emitting diodes for conversion of electrical energy into light energy.
[0144]
The transducer of the present invention is capable of use particularly as an artificial muscle, actuator, sensor, or electrical generating element due to the dielectric and mechanical characteristics of the transducer of the present invention. An artificial muscle is anticipated to be used for applications such as robots, nursing equipment, rehabilitation training equipment, or the like. An embodiment as an actuator will be explained below as an example of the present invention.
[0145]
[FIGS. 1 to 4]
FIG. 1 shows a cross sectional view of an actuator 1 of the present embodiment in which dielectric layers are stacked. In this embodiment, the dielectric layer is composed of 2 dielectric layers, for example. The actuator 1 is equipped with dielectric layers 10a and 10b, electrode layers 11 a and 11 b, a wire 12, and an electrical power source 13. The electrode layers 11 a and 11 b cover a respective contacting surface of the dielectric layer, and these are connected to the electrical power source 13 through respective wires 12.
[0146]
The actuator 1 may be driven by application of a voltage between the electrode layer 11 and the electrode layer 11 b. By application of voltage, the dielectric layers 10a and 10b become thinner due to dielectric properties, and this results in elongation parallel to the faces of the electrode layers 11 a and 11 b. That is to say, it is possible to convert electrical energy into force or mechanical energy of movement or displacement.
[0147]
FIG. 2 shows a cross sectional view of an actuator 2 of the present embodiment in which the dielectric layer and electrode layer are stacked. According to the present embodiment, the dielectric layer is composed of 3 layers, and the electrode layer is composed of 4 layers, for example. The actuator 2 is equipped with dielectric layers 20a, 20b, and 20c, electrode layers 21 a, 21 b, 21 c and 21 d; the wire 22; and the electrical power source 23. The electrode layers 21 a, 21 b, 21 c, and 21 d each cover a respective contacting surface of dielectric layer, and these are connected to the electrical power source 23 through respective wires 22. The electrode layers are connected alternatingly to sides of different voltage, and the electrode layers 21 a and 21 c are connected to a different side from that of the electrode layers 2b and 21 d.
[0148]
By application of voltage between the electrode layer 21 a and electrode layer 21 b, application of voltage between the electrode layer 21 b and electrode layer 21 c, and application of voltage between the electrode layer 21 c and electrode layer 21 d, it is possible to drive the actuator 2. By application of voltage, the dielectric layers 20a, 20b, and 20c become thinner due to dielectric properties, and this results in elongation parallel to the faces of the electrode layers 21 a, 21 b, 21 c, and 21 d. That is to say, it is possible to convert electrical energy into force or mechanical energy of movement or displacement.
[0149]
Although the embodiment of an actuator was described as an example of the transducer of the present invention, when mechanical energy (such as pressure or the like) is applied from outside to the transducer of the present invention, it is possible to generate an electrical potential difference as electrical energy between the mutually insulated electrode layers. That is to say, use is possible as a sensor for the conversion of mechanical energy into electrical energy. This embodiment of a sensor will be described below.
[0150]
FIG. 3 shows structure of the sensor 3 of the present embodiment. The sensor 3 has a structure in which the dielectric layer 30 is disposed between upper electrode layers 31 a, 31 b, and 31 c and lower electrode layers 32a, 32b, and 32c arranged in a matrix-like pattern.
According to the present embodiment, for example, the electrode layers are disposed in a matrix pattern of 3 rows in the vertical direction and horizontal direction, respectively. The face of each electrode layer not contacting the dielectric layer 30 may be protected by an insulating layer. Moreover, the dielectric layer 30 may comprise 2 or more layers of the same dielectric layer containing organopolysiloxane.
[0151 ]
When an external force is applied to the surface of this sensor 3, the thickness of the dielectric layer 30 between the upper electrode layer and the lower electrode layer changes at the pressed location, and there is a change in static capacitance between the electrode layers due to this change. By measurement of the electrical potential difference between the electrode layers due to this change of static capacitance between these electrode layers, it is possible to detect the external force. That is to say, this embodiment may be used as a sensor for conversion of mechanical energy into electrical energy.
[0152]
Furthermore, although the opposing electrode layers sandwiching the dielectric layer were formed as 3 pairs in the sensor 3 of the present embodiment, the number, sizes, placement, or the like of electrodes may be selected appropriate according to application.
[0153]
An electricity generating element is a transducer for conversion of mechanical energy into electrical energy. This electricity generating element may be used for devices that generate electricity, beginning with electricity generation by natural energy such as wave power, water power, water power, or the like, as well as generation of electricity due to vibration, impact, pressure change, or the like. An embodiment of this electricity generating element will be described below.
[0154]
FIG. 4 shows a cross sectional view of the electricity generating element 4 of the present embodiment, in which dielectric layers are stacked. In this embodiment, the dielectric layer is composed of 2 dielectric layers, for example. The electricity generating element 4 is composed of the dielectric layers 40a and 40b and the electrode layers 41 a and 41 b. The electrode layers 41 a and 41 b are arranged covering one face of the respective contacted dielectric layer.
[0155]
The electrode layers 41 a and 41 b are connected electrically to a non-illustrated load. This electricity generating element 4 may generate electrical energy by change of the static capacitance by change of the distance between the electrode layers 41 a and 41 b. That is to say, due to change in the shape of the element between the electrode layers 41 a and 41 b in the electrostatic charge-induced state due to electrostatic field formed by the dielectric layers 40a and 40b, the charge distribution becomes biased, the static capacitance between electrode layer changes due to such bias, and an electrical potential difference arises between the electrode layers.
[0156]
In the present embodiment, due to change from a state (upper drawing) of applied compression force in the direction parallel to the faces of the electrode layers 41 a and 41 b of the electricity generating element 4 shown in FIG. 4 to a state (lower drawing) of non application of compression as shown in the same figure, an electrical potential difference arises between the electrode layers 41 a and 41 b, and it is possible to realize the function of an electricity generating element by output of this change of electrical potential difference as electrical power. That is to say, it is possible to convert mechanical energy into electrical energy. Moreover, multiple elements may be arranged on a substrate, and it is possible to construct an electricity generating device that generates a greater amount of electricity by series or parallel connection of such multiple elements.
[0157]
The transducer of the present invention may operate in air, water, vacuum, or organic solvent. Moreover, the transducer of the present invention may be sealed appropriately according to the environment of use of the transducer. No particular limitation is placed on the sealing method, and this sealing method is exemplified by sealing using a resin material or the like.
Industrial Applicability
[0158]
The curable organopolysiloxane composition for transducers of the present invention may be used appropriately for the manufacture of a transducer. The curable organopolysiloxane composition for transducers of the present invention, rather than simply an uncured curable composition, may comprise a so-called B stage material in a state in which the reactive organopolysiloxane is partially reacted, and curing is incomplete. A B stage material of the present invention is exemplified by a material in a state that is gel-like or has flowability.
Therefore the embodiments of the present invention also comprise a member in a state where the curing reaction of the curable organopolysiloxane composition for transducers has partially progressed, and in which the member for transducers is in a state that is gel-like or fluid.
Moreover, the member for transducers in this type of semi-cured state may be composed of a single layer or stacked layers of the thin film-like silicone elastomer.
EXAMPLES
[0159]
In order to embody the present invention, practical examples will now be given. However, it should be understood that these practical examples do not limit the scope of the present invention. Furthermore, "%" below represents percent by weight. The property of each silicone elastomer composition was measured by following method.
[0160]
[Mechanical Strength]
This silicone elastomer composition was press cured for 15 minutes at 150°C, and then was post-cured in an oven for 60 minutes at 150°C. Based on J IS K 6249, Young's modulus, tensile strength, elongation at break, and tear strength were measured for the obtained cured article. In order to measure mechanical strength, a sheet of 2 mm thickness was made.
[Electrical Characteristics]
The silicone elastomer composition was press cured for 15 minutes at 150°C to produce a 0.07 mm thick sheet, and insulation breakdown strength as measured using an electrical insulation breakdown voltage oil tester, i.e. PORTATEST 100A-2 manufactured by Soken Electric Co., Ltd. In the same manner, the silicon elastomer composition was press cured for 15 minutes at 150 °C for 15 minutes to produce a sheet of 1 mm thickness. Specific dielectric constant was measured under 23 °C temperature and 1 MHz measurement frequency conditions using a TR-1100 dielectric constant-tangent measurement device manufactured by Ando Electric Co., Ltd. Moreover, the same sample was evaluated for volume resistivity using a model 4339A high resistance meter (volume resistance measurement device, manufactured by HP).
[0161 ]
Practical Example 1
A mixture of 100 parts of dimethylpolysiloxane A (vinyl content = 0.23 mass%) of 2,000 mPa- s (viscosity at 25° C) and capped at both molecular terminals with dimethylvinylsiloxy groups and 3.3 parts of trimethylmethoxysilane and 330 parts of 0.25 μιη average particle size spherical titanium oxide particles (CR-80, Ishihara Sangyo Kaisha, Ltd.) were kneaded using a twin screw kneading apparatus (manufactured by Kurimoto, Ltd., model name = "S4KRC Kneader," L/D ratio = 7.0, void cross-sectional area = 8,332 mm2, screw pitch = 80 mm, rotation rate = 500 rpm, calculated free volume = 11 ,998 L/hr, and screw diameter = 50 mm). The kneading conditions of the twin screw kneading apparatus were as follows: ~\ 50 1 jacket temperature, and 1 minutes residence time. The feed rate of the dimethylpolysiloxane A and trimethylmethoxysilane mixture was 4 kg/hr, and the feed rate of the titanium oxide was 16 kg/hr. The concentration of titanium oxide in the obtained silicone elastomer base was about 76 mass%.
[0162]
To the obtained silicone rubber base were added 0.3 parts of
dimethylsiloxane-methylhydrogensiloxane copolymer terminated at both molecular terminals with trimethylsiloxy groups (degree of polymerization = 6, SiH content = 0.73 mass%), 6.0 parts of dimethylsiloxane-methylhydrogensiloxane copolymer terminated at both molecular terminals with dimethylhydrogensiloxy groups (degree of polymerization = 14, SiH content = 0.13 mass%), 0.2 parts by mass of a 1 .7% dimethylvinylsiloxy group-doubly terminated dimethylpolysiloxane solution of 1 ,3-diethenyl-1 ,1 ,3,3-tetramethyldisiloxane platinum complex, and 3.1 parts of a 0.5% dimethylvinylsiloxy group-doubly terminated dimethylpolysiloxane solution of phenylbutynol as a reaction control agent. The mixture was blended uniformly (about 10 minutes), and a silicone rubber composition was obtained. The molar ratio (SiH groups/vinyl groups) of total SiH functional groups to total vinyl groups in this silicone elastomer composition was 1 .
[0163]
The mechanical strength and electrical characteristics of the electrically active silicone elastomer sheet obtained by curing a single layer of the silicone rubber composition obtained in Practical Example 1 were measured by the below described methods. Results of measurement of mechanical strength and electrical characteristics are shown in Table 2.
[0164]
[Table 2]
Figure imgf000051_0001
[0165]
Practical Example 2
Except for use of a twin screw extruder (manufactured by Plastic Technology Co., Ltd., model name BT-30-SL) rather than the twin screw kneading apparatus of the Practical Example 1 , a curable organopolysiloxane composition for transducers and component for transducers of Practical Example 2 were prepared in the same manner as in Practical Example 1.
[0166]
Practical Example 3
Except for use of a single screw blade type kneading apparatus (manufactured by KCK Engineering Co., Ltd., model name KCK 130X2-65X) rather than the twin screw kneading apparatus of the Practical Example 1 , a curable organopolysiloxane composition for transducers and component for transducers of Practical Example 3 were prepared in the same manner as in Practical Example 1 .
[0167]
Reference Examples:
Silicone elastomer compositions may be prepared by following examples of compositional formulation, and using intermediate raw materials of silicone elastomer bases obtained by keading procedure with the twin screw kneading apparatus of the Practical Example 1. The production method is excellent in the performance, mass-productivity and the like of the silicone elastomer composition for transducer use of this present invention.
[0168] Reference Example 1 : "Using a silicone elastomer base including barium titanate, with surface-treatement agent"
To 14.22% of dimethylpolysiloxane (B2) (0.23% vinyl content) having a viscosity of 2,000 mPa-s at 25 °C and capped by dimethylvinylsiloxy groups at both terminals are added 85.35% spherical barium titanate of 1 .0 μιη average particle diameter (produced by Fuji Titanium Industry Co., Ltd., HPBT-1 B), 0.356% trimethoxysilyl singly-terminated dimethylvinyl singly-terminated
polysiloxane (average degree of polymerization = 25), and 0.071 % of
1 ,1 ,3-trimethyl-3,3-diphenyl-1-carobxydecyldisiloxane. By kneading said composition uniformly using the twin screw kneading apparatus of the Practical Example 1 , a silicone elastomer base is obtained.
[0169]
To this silicone elastomer base are added dimethylpolysiloxane (B2), dimethylhydrogensiloxy group-doubly molecular chain terminated polydimethylsiloxane (An , SiH content = 0.155%), trimethylsiloxy group-doubly molecular chain terminated
dimethylsiloxane-methylhydrogensiloxane copolymer (A22, 0.83% SiH content), 0.67% (as platinum) of the platinum complex of 1 ,3— diethenyl— 1 ,1 ,3,3-tetramethyldisiloxane complex dissolved in dimethylvinylsiloxy group doubly terminated methylpolysiloxane, as well as tetramethyltetravinylcyclotetrasiloxane as a reaction control agent. The mixture is mixed until uniform (about 10 minutes) to obtain a silicone elastomer composition. Here, the molar ratio of all SiH functional groups over all vinyl groups in this silicone elastomer composition (SiH groups/vinyl groups) is 1.3.
[0170]
Reference Example 2: "Using a silicone elastomer base including barium titanate, with surface-treatement agent"
To 100 mass parts of dimethylpolysiloxane (0.23% vinyl content) having a viscosity of 2,000 mPa-s at 25 °C and capped by dimethylvinylsiloxy groups at both terminals are added 293 mass parts of barium titanate of 0.4 μιη average particle diameter (produced by Sakai Chemical Industry Co., Ltd., BT-04), and 4.1 mass parts of methyltrimethoxysilane. By keading said composition uniformly using the twin screw kneading apparatus of the Practical Example 1 , a silicone elastomer base is obtained.
[0171 ]
To the silicone elastomer base are added 16.12 mass parts of dimethylhydrogensiloxy group-doubly molecular chain terminated polydimethylsiloxane (SiH content = 0.15%), 0.13 mass parts of trimethylsiloxy group-doubly molecular chain terminated
dimethylsiloxane-methylhydrogensiloxane copolymer (0.75% SiH content), 80 ppm (as platinum, the platinum metal content is calculated by mass parts and to said mixture of dimethylpolysiloxanes in the silicone elastomer bases) of the platinum complex of
1 ,3— diethenyl— 1 ,1 ,3,3-tetramethyldisiloxane complex as curing agent, as well as 0.009 mass parts of 2-phenyl-3-butyn-2-ol as a reaction control agent, and 0.62 mass parts of
tetramethyltetravinylcyclotetrasiloxane (31 .4% vinyl content). The mixture is mixed until uniform (about 10 minutes) to obtain a silicone elastomer composition.
Here, the molar ratio of all SiH functional groups over all vinyl groups in this silicone elastomer composition (SiH groups/vinyl groups) is 1.3.
[0172]
Reference Example 3: "Using a silicone elastomer base including barium titanate, with two surface-treatement agents"
To 100 mass parts of dimethylpolysiloxane (0.23% vinyl content) having a viscosity of 2,000 mPa-s at 25 °C and capped by dimethylvinylsiloxy groups at both terminals are added 325 mass parts of barium titanate of 0.4 μιη average particle diameter (produced by Sakai Chemical Industry Co., Ltd., BT-04), 0.12 mass parts of 1 ,3-divinyl-1 ,1 ,3,3-tetramethyldisilazane, and 2.46 mass parts of 1 ,1 ,1 ,3,3,3-hexamethyldisilazane. By keading said composition uniformly using the twin screw kneading apparatus of the Practical Example 1 , a silicone elastomer base is obtained.
[0173]
To the silicone elastomer base are added 16.93 mass parts of dimethylhydrogensiloxy group-doubly molecular chain terminated polydimethylsiloxane (SiH content = 0.15%), 0.14 mass parts of trimethylsiloxy group-doubly molecular chain terminated
dimethylsiloxane-methylhydrogensiloxane copolymer (0.75% SiH content), 80 ppm (as platinum, the platinum metal content is calculated by mass parts and to said mixture of
dimethylpolysiloxanes in the silicone elastomer bases) of the platinum complex of
1 ,3— diethenyl— 1 ,1 ,3,3-tetramethyldisiloxane complex as curing agent, as well as 0.009 mass parts of 2-phenyl-3-butyn-2-ol as a reaction control agent and 0.67 mass parts of
tetramethyltetravinylcyclotetrasiloxane. The mixture is mixed until uniform (about 10 minutes) to obtain a silicone elastomer composition.
Here, the molar ratio of all SiH functional groups over all vinyl groups in this silicone elastomer composition (SiH groups/vinyl groups) is 1.3.
[0174]
Reference Example 4: "Using a silicone elastomer base including barium titanate, with two surface-treatement agents"
To 100 mass parts of dimethylpolysiloxane (0.23% vinyl content) having a viscosity of 2,000 mPa-s at 25 °C and capped by dimethylvinylsiloxy groups at both terminals are added 296 mass parts of barium titanate of 0.4 μιη average particle diameter (produced by Sakai Chemical
Industry Co., Ltd., BT-04), 1.25 mass parts of methyltrimethoxysilane, and 0.42 mass parts of 1 ,1 ,3-trimethyl-3,3-diphenyl-1-carobxydecyldisiloxane. By keading said composition uniformly using the twin screw kneading apparatus of the Practical Example 1 , a silicone elastomer base is obtained.
[0175]
To the silicone elastomer base are added 15.42 mass parts of dimethylhydrogensiloxy group-doubly molecular chain terminated polydimethylsiloxane (SiH content = 0.15%), 0.28 mass parts of trimethylsiloxy group-doubly molecular chain terminated
dimethylsiloxane-methylhydrogensiloxane copolymer (0.75% SiH content), 80 ppm (as platinum, the platinum metal content is calculated by mass parts and to said mixture of
dimethylpolysiloxanes in the silicone elastomer bases) of the platinum complex of
1 ,3— diethenyl— 1 ,1 ,3,3-tetramethyldisiloxane complex as curing agent, as well as 0.009 mass parts of 2-phenyl-3-butyn-2-ol as a reaction control agent and 0.63 mass parts of
tetramethyltetravinylcyclotetrasiloxane. The mixture is mixed until uniform (about 10 minutes) to obtain a silicone elastomer composition.
Here, the molar ratio of all SiH functional groups over all vinyl groups in this silicone elastomer composition (SiH groups/vinyl groups) is 1.3.
[0176]
Reference Example 4: "Using two types of silicone elastomer bases including barium titanate or carbon black each, with surface-treatement agent"
To 14.22% of dimethylpolysiloxane (A22) (0.23% vinyl content) having a viscosity of 2,000 mPa-s at 25 °C and capped by dimethylvinylsiloxy groups at both terminals are added 85.35% spherical barium titanate of 1 .0 μιη average particle diameter (produced by Fuji Titanium Industry Co., Ltd., HPBT-1 B), 0.356% trimethoxysilyl singly-terminated dimethylvinyl singly-terminated
polysiloxane (average degree of polymerization = 25), and 0.071 % of
1 ,1 ,3-trimethyl-3,3-diphenyl-1-carobxydecyldisiloxane. By keading said composition uniformly using the twin screw kneading apparatus of the Practical Example 1 , a silicone elastomer base #1 is obtained.
Furthermore, to 50.00% of dimethylpolysiloxane (A22) (0.23% vinyl content) having a viscosity of 2,000 mPa-s at 25 °C and capped by dimethylvinylsiloxy groups at both terminals are added 50.00% of Carbon Black (produced by Cancarb corporation, Thermax Floform N990). By keading said composition uniformly using the twin screw kneading apparatus of the Practical Example 1 , a silicone elastomer base #2 is obtained.
[0177]
To the silicone elastomer base #1 and the silicone elastomer base #2 are added
dimethylpolysiloxane (A22), dimethylhydrogensiloxy group-doubly molecular chain terminated polydimethylsiloxane (A112, SiH content = 0.015%), trimethylsiloxy group-doubly molecular chain terminated dimethylsiloxane-methylhydrogensiloxane copolymer (A12i , 0.75% SiH
content), 0.67% (as platinum) of the platinum complex of
1 ,3— diethenyl— 1 ,1 ,3,3-tetramethyldisiloxane complex dissolved in dimethylvinylsiloxy group doubly terminated methylpolysiloxane, as well as tetramethyltetravinylcyclotetrasiloxane as a reaction control agent. The mixture is mixed until uniform (about 10 minutes) to obtain a silicone elastomer composition. Here, the molar ratio of all SiH functional groups over all vinyl groups in this silicone elastomer composition (SiH groups/vinyl groups) is 1.3.
[0178]
As shown in Table 2, the curable organopolysiloxane composition was obtained by the production method of present invention , and thus a silicone elastomer was provided that had excellent mechanical characteristics (as represented by elongation at break) and dielectric characteristics (as represented by the dielectric constant). Moreover, by optimization of the crosslinking structure and the inorganic fine particles, it is possible to design a material according to the desired transducer application.
Furthermore, the silicone elastomer obtained from the curable organopolysiloxane composition of the present invention attains high dielectric properties even in the low voltage region.
Reference Numerals
[0179]
1 ,2 actuator
10a, 10b, 20a, 20b, 20c dielectric layer
11 a, 11 b, 21 a, 21 b, 21 c, 21 d electrode layer (electrically conductive layer)
12, 22 wire
13, 23 electrical power source
3 sensor
30 dielectric layer
31 a, 31 b, 31 c upper electrode layer
32a, 32b, 32c lower electrode layer
4 electricity generating element
40a, 40b dielectric layer
41 a, 41 b electrode layer
51 a Feed port
51 b Discharge port
52 Twin screws
52a, 52b, 52c Kneading disk
53 Drive device 54 ... Feeder
510 ... Twin screw extruder

Claims

What is Claimed:
1 . A production method of a curable organopolysiloxane composition for transducer use
comprising a step of kneading a composition for kneading including: a curable
organopolysiloxane, and at least one type of filler, wherein the kneading is performed using an extruder or kneading apparatus.
2. The production method of a curable organopolysiloxane composition for transducer use of claim 1 , wherein, the at least one type of filler comprises at least one type of filler selected from the group consisting of high dielectric fillers, high electrical conductivity fillers, electrically insulating fillers, and reinforcing fillers.
3. The production method of a curable organopolysiloxane composition for transducer use of claim 1 or claim 2, wherein the at least one type of filler comprises (D) dielectric inorganic fine particles having specific dielectric constant at 1 kHz greater than or equal to 10 at room temperature.
4. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 3, wherein the composition for kneading further includes at least one type of surface treatment agent.
5. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 4, wherein the extruder or kneading apparatus is at least one mechanical means selected from the group consisting of twin screw extruders, twin screw kneaders, and single screw blade-type extruders.
6. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 5, wherein the extruder or kneading apparatus is a twin screw extruders having a device free volume defined as "void cross-sectional area of the apparatus (mm2) χ screw pitch (mm) χ rotation rate (rpm) χ 60/1 ,000,000 (LVhr)" of at least 5,000 (L/hr).
7. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 6, wherein the step of keading the composition for kneading is a step of keading with the the filler content of greater than or equal to 50 mass% of the total composition using said extruder or kneading apparatus.
8. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 7, wherein the step of keading the composition for kneading is performed in a temperature range of 100 to 180 °C.
9. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 8, wherein the step of keading the composition for kneading is performed using an extruder at a residence time in the range of 30 seconds to 5 minutes.
10. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 9, which is characterized by using the composition obtained by the step of kneading the composition for kneading as an intermediate raw material for a curable organopolysiloxane composition for transducer use.
11 . The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 10, which is characterized by using the composition obtained by kneading a curable organopolysiloxane, (D) dielectric inorganic fine particles having specific dielectric constant at 1 kHz greater than or equal to 10 at room temperature and at least one type of surface treatment agent in an amount that the filler content of greater than or equal to 70 mass% of the total composition as an intermediate raw material for a curable organopolysiloxane composition for transducer use.
12. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 11 , wherein the curable organopolysiloxane is a hydrosilylation reaction curable organopolysiloxane.
13. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 12, wherein the curable organopolysiloxane is at least one of
(A11 ) at least one type of organohydrogenpolysiloxane having silicon atom-bonded hydrogen atoms at both molecular terminals, a weight fraction of hydrogen atoms being 0.1 to 1 .0% by weight;
(A12) at least one type of organohydrogenpolysiloxane having at least 3 silicon atom-bonded hydrogen atoms in a single molecule, a weight fraction of hydrogen atoms being 0.03 to 2.0% by weight; and
(A2) at least one type of organopolysiloxane having at least 2 alkenyl groups in a single molecule, a weight fraction of the alkenyl groups being 0.05 to 0.5% by weight.
14. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 13, wherein the filler comprises one or more types of inorganic fine particles selected from the group consisting of titanium oxide, barium titanate, strontium titanate, lead titanate zirconate, and barium titanate, and composite metal oxides in which the barium and titanium positions of barium titanate are partially replaced by an alkaline earth metal, such as calcium or strontium; zirconium; or rare earth metal such as yttrium, neodymium, samarium, or dysprosium.
15. The production method of a curable organopolysiloxane composition for transducer use of any one of claims 1 to 14, which is characterized by blending another curable
organopolysiloxane, a vulcanizing agent, a curing catalyst, or other component with the intermediate raw material obtained by kneading a composition for kneading including: a curable organopolysiloxane, and at least one type of filler using an extruder or kneading apparatus.
16. A production method of a member for transducers comprising a step of at least partial curing of the curable organopolysiloxane composition for transducers obtained by the production method of any one of claims 1 to 15.
17. A production method of transducers comprising a step of disposing a silicone elastomer intermediate layer between at least one pair of electrodes, wherein the silicone elastomer intermediate layer formed by curing or at least partial curing of the curable organopolysiloxane composition for transducers obtained by the production method of any one of claims 1 to 15.
18. The production method of transducers of claim 17, wherein at least two of the silicone elastomer layers are stacked as the silicone elastomer intermediate layer.
PCT/US2013/077855 2012-12-28 2013-12-26 Production method of curable organopolysiloxane composition for transducers WO2014105979A1 (en)

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