Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
  • C04B35/632—Organic additives
  • C04B35/634—Polymers
  • C04B35/63404—Polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C04B35/63424—Polyacrylates; Polymethacrylates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
  • C04B35/462—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates
  • C04B35/465—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates
  • C04B35/468—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates
  • C04B35/4682—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates based on BaTiO3 perovskite phase
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
  • C04B35/632—Organic additives
  • C04B35/634—Polymers
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
  • C04B35/632—Organic additives
  • C04B35/634—Polymers
  • C04B35/63448—Polymers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • C04B35/63456—Polyurethanes; Polyisocyanates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G4/00—Fixed capacitors; Processes of their manufacture
  • H01G4/002—Details
  • H01G4/018—Dielectrics
  • H01G4/06—Solid dielectrics
  • H01G4/08—Inorganic dielectrics
  • H01G4/12—Ceramic dielectrics

Definitions

• Aqueous ceramic casting compound process for producing the casting compound and use of the casting compound
• the invention relates to a ceramic casting compound (slip) which has a ceramic powder, an aqueous dispersion medium and a binder.
• a ceramic casting compound is known from WO 94/07808.
• a process for the production of the casting compound and a use of the casting compound are specified.
• a ceramic casting compound is used, for example, to produce a ceramic green sheet.
• a casting compound with an aqueous dispersion medium is preferred.
• the ceramic casting compound resulting from WO 94/07808, which is suitable for producing a ceramic green sheet, has an emulsion copolymer of an ester of an acrylic and / or methacrylic acid as a binder.
• Ceramic green foils are used to produce a multilayer ceramic body, for example a multilayer capacitor.
• Several green foils, possibly with a metallization, are stacked on top of one another, laminated, debindered and sintered together.
• Green foils which are as thin as possible are used to reduce the size of the multilayer body.
• the capacitance of the capacitor can also be increased using thin green foils.
• the object of the invention is to provide a ceramic casting compound with an aqueous dispersion medium, with the aid of which a thin ceramic green sheet can be produced, which also has sufficient elasticity and the necessary tensile strength for further processing.
• a ceramic casting compound which has a ceramic powder, an aqueous dispersion medium and a binder, characterized in that the binder comprises polyurethane.
• a polyurethane is suitable as a binder, which is used, for example, in the production of a polyurethane foam, an adhesive or a lacquer.
• a chain of a polyurethane is extremely flexible due to its molecular structure.
• the green sheet produced with the aid of the polyurethane can also have a tensile strength which is tailored to the further processing of the green sheet.
• a thin green sheet can in particular also be self-supporting, i.e. can be processed without a carrier like a plastic film. It is not necessary to specifically influence the mechanical properties of a green sheet, for example by incorporating a soft substituent from a polymeric binder to lower its glass transition temperature.
• a plasticizer as an additive to the casting compound can also be dispensed with.
• the binder has a copolymer.
• the binder is an emulsion copolymer made from a polyacrylate and a polyurethane.
• Another component of the copolymer can also be cellulose, polyacrylamide, polyvinyl alcohol and / or styrene.
• a monomer with a corresponding In the functional group a certain property of the binder can be changed in a targeted manner (eg the solubility of the binder in water).
• a polyurethane binder can be mixed with another binder.
• This further binder can in particular have polyacrylate. It is particularly advantageous if the binders have a similar pH stability.
• the casting compound has a binder with a molecular weight in a range between 10,000 and 120,000 g / mol.
• the binder is preferably in the form of a microsphere with an average particle size in a range between 20 and 300 nm, a particle size below 100 nm being possible in particular with a polyurethane.
• This particle size leads to a good solubility of the polyurethane in water. This ensures a high stability of the casting compound. Solid components remain evenly distributed in the casting compound, i.e. sedimentation (gravitational drainage) does not take place.
• a small green particle size of the binder enables a high green density to be achieved in a ceramic green body.
• the casting compound has a pH value in a range between 5 and 10.
• a polyurethane is stable, i.e. for example, it does not tend to agglomerate.
• An additional stabilizer for the polyurethane is not necessary.
• the ceramic powder of the casting compound has at least one substance selected from the group boron, carbon, oxygen, sulfur, nitrogen, lithium, sodium, potassium, beryllium, magnesium, calcium, strontium, barium, aluminum, gallium, Indium, titanium, zircon, bismuth and / or manganese is selected. Is.
• the ceramic powder has barium titanate. Barium titanate is mainly used as a dielectric in multilayer capacitors.
• a method for producing a ceramic casting compound which has a ceramic powder, an aqueous dispersion medium and a binder with polyurethane.
• a ceramic powder for this purpose, an aqueous dispersion of the ceramic powder and an aqueous dispersion of the binder are mixed.
• a ceramic casting compound described here is used to produce a ceramic green body, for example a green film. With the aid of the casting compound, it is possible in particular to produce a green film which has a thickness in a range between 1 and 30 ⁇ m.
• a thin green film which has barium titanate as the ceramic powder, for example, can be used to produce a multilayer capacitor of high capacitance and low overall height.
• a casting compound with an aqueous dispersion medium can be used.
• a polyurethane has a relatively high solubility in water. This leads to a stable casting compound with a high green density.
• a polyurethane can easily be combined with another binder (multi-component binder).
• Monomers of a polyurethane can easily be subjected to a copolymerization. This makes it possible to influence a property of a binder specifically at the molecular level.
• the green sheet has mechanical properties that make further processing of the green sheet possible (combination of flexibility and tensile strength).
• the production of the casting compound is explained in more detail using several exemplary embodiments. It also shows how the mechanical properties of a ceramic green sheet can be influenced by the composition of the binder.
• a ceramic powder (Y5V®, company Kyorix, Japan) with an average grain size of 0.4 ⁇ m is mixed with 12 g of a polyammonium acrylate (zirconium oxide balls (diameter 1 mm) as grinding medium).
• Byk 154® from Byk Chemie
• 390 g of a 0% strength are added to this dispersion with slow stirring aqueous dispersion of an aliphatic polyester-polyurethane copolymer (pH: 7-8.5) was added.
• the mixture is homogenized by stirring for three hours, an additional 10 g of a wetting agent (SE-F®, Air Products) being introduced.
• SE-F® wetting agent
• the homogenized casting compound is degassed under vacuum.
• the viscosity of the casting compound is approximately 24 mPas.
• a ceramic green film with a thickness of 17 ⁇ m is obtained by pulling out with a film drawing frame with a corresponding gap thickness on a carrier film made of polypropylene.
• the elastic modulus of this green sheet is 523.80 MPa and the maximum tensile strength is 7.36 MPa.
• a green film with a thickness of 4 .mu.m can be produced from the casting compound described and can easily be detached from the carrier film.
• Another exemplary embodiment differs from the first in that, instead of a polyester-polyurethane copolymer, a 75:25 mixture of a polyurethane and a polyacrylate is used as a binder (pH 8.8-9.2).
• the minimum film forming temperature of the casting compound is 18 ° C and the viscosity 0.5 to 1 Pas.
• the modulus of elasticity is 930 Mpa.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Structural Engineering (AREA)
• Inorganic Chemistry (AREA)
• Power Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)

Applications Claiming Priority (3)

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• 2000
  • 2000-01-03 JP JP2000594748A patent/JP2002535231A/ja not_active Withdrawn
  • 2000-01-03 WO PCT/DE2000/000020 patent/WO2000043328A1/de not_active Application Discontinuation
  • 2000-01-03 EP EP00903495A patent/EP1152999A1/de not_active Withdrawn
  • 2000-01-03 US US09/857,787 patent/US6521686B1/en not_active Expired - Fee Related

Non-Patent Citations (1)

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