WO1992022509A1 - Compositions liantes polymeres pour ceramiques - Google Patents

Compositions liantes polymeres pour ceramiques Download PDF

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Publication number
WO1992022509A1
WO1992022509A1 PCT/US1992/005044 US9205044W WO9222509A1 WO 1992022509 A1 WO1992022509 A1 WO 1992022509A1 US 9205044 W US9205044 W US 9205044W WO 9222509 A1 WO9222509 A1 WO 9222509A1
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ceramic
monomer
composition
solvent
polymer
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PCT/US1992/005044
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English (en)
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Jong Hoon Han
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Hexcel Corporation
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Publication of WO1992022509A1 publication Critical patent/WO1992022509A1/fr

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    • 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
    • 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
    • C04B35/63404—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
    • C04B35/622—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
    • 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
    • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
    • C08K5/0025—Crosslinking or vulcanising agents; including accelerators
    • 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
    • C08K5/04—Oxygen-containing compounds
    • C08K5/10—Esters; Ether-esters
    • C08K5/101—Esters; Ether-esters of monocarboxylic acids
    • C08K5/103—Esters; Ether-esters of monocarboxylic acids with polyalcohols

Definitions

  • the present invention relates in general to binders used in ceramic formulations for molding ceramic parts. More particularly, the present invention is directed to compositions of stable solutions of polymer and monomer which are useful ceramic binders for making intricate three dimensional advanced ceramic parts.
  • Ceramic materials are used in a wide range of industrial applications ranging from electronics to structural material to the arts and ornamental applications. Because of their diversified utility, ceramic parts are prepared in a wide range of shapes and sizes which vary from tiny electronic components to large structural pieces. Ceramic parts can be prepared by a number of different processes and the choice of formation process depends to a great extent upon the size, shape, and the ultimate use of the ceramic part. Large three dimensional parts having intricate detail are typically prepared using casting and reinfiltration techniques. On the other hand, certain parts applications may require the use of manufacturing processes oi torming techniques other than casting, for example, pultrusion, injection, preform and other forming processes as are known to those skilled in the art.
  • Casting techniques typically include forming slurries which contain a fine sinterable ceramic raw material and then casting the slurry in the form of a green sheet. The green sheet can then be dried and punched to form the desired shape. While these techniques provide parts with complex and intricate shapes, there are significant disadvantages which are associated with casting processes. The process .is time consuming and costly. Moreover, the green sheets which result from the casting process are typically very fragile, have very low strength, and have material densities which are lower than the preferred part density.
  • Forming techniques for continuously reinforced parts are much less costly than typical casting techniques and allow the formation of green parts having increased flexibility and physical integrity.
  • the slurries which are used to form parts using this methodology display an increased plasticity achieved through the use of polymeric ceramic binders. These binders are combined with the sinterable ceramic prior to the forming process to give the raw material a certain degree of plasticity. This plasticity provides some improved flow characteristics which are particularly useful when the plastic deformation methods are used for forming ceramic parts.
  • polymeric binders A variety of polymeric binders has been widely utilized in the field of fabricating ceramic parts and they include both water soluble and organic solvent soluble polymeric binders such as waxes, starches, polyvinylalcohol, gums, acrylates, celluloses, polyglycols, butyrals, epoxies and acetates.
  • water soluble and organic solvent soluble polymeric binders such as waxes, starches, polyvinylalcohol, gums, acrylates, celluloses, polyglycols, butyrals, epoxies and acetates.
  • Polymeric binders are also incorporated in raw materials for forming ceramic parts using casting techniques.
  • the use of these polymer binders provides advantages during the punching process in that the green part has increased mechanical strength and it can be handled with less caution prior to sintering.
  • the ceramic green parts In order to prepare large three dimensional ceramic parts using conventional plastic green part fabrication processes, the ceramic green parts must exhibit both tack and drape.
  • the known polymeric ceramic binder compositions do not have adequate drape or tack or both properties when they are used in combination with ceramic raw materials. Consequently, these polymer ceramic binders are not suitable for processing many types of ceramic parts. As a result, the more costly casting and reinfiltration techniques which generally do not incorporate polymeric binders must be utilized to form these intricately shaped parts.
  • conventional polymeric ceramic binders generally provide improved raw material handling properties during the green part plastic formation process, significant problems exist when these polymeric binders and plastic formation techniques are utilized to prepare intricately-shaped ceramic parts and ceramic prepregs.
  • a ceramic binder composition which, when combined with sinterable material, exhibits drape and tack properties suitable for molding intricately shaped articles using conventional plastic molding techniques. It would also be desirable to provide a ceramic binder composition which can be incorporated with a sinterable material to prepare ceramic parts which have high green part strength and easy presintering handleability. It would additionally be desirable to provide a ceramic binder composition which burns cleanly upon sintering. It would also be desirable to provide a ceramic binder composition which has improved extended shelf life.
  • the present invention provides polymer compositions which are suitable for use as ceramic binders in the formation of ceramic green parts.
  • binder compositions of the present invention are combined with sinterable material, the resulting ceramic formulations display exceptional tack and drape properties. Accordingly, they have particular utility in ceramic formulations which are utilized to form advanced three dimensional reinforced and non reinforced ceramic parts.
  • the polymeric ceramic binders of the present invention provide added strength, flexibility, and ease in handling a ceramic green part prior to its final curing relative to conventional binders. Moreover, the ceramic binders of the present invention will burn cleanly during burn-out, leaving minimal char which can interfere with the desired properties of the sintered ceramic part.
  • the ceramic binder compositions of the present invention are stable solutions having at least one polymer, and at least one monomer, the polymer being soluble in the monomer.
  • the system preferably includes a polymerization initiator capable of initiating the polymerization of the monomers. Solvents may or may not be added to the system to reduce viscosity.
  • Solvents which are suitable for use in the ceramic binder compositions of the present invention include organic solvents typically used in polymer processing and solution polymerization processes.
  • Polymers having utility in the ceramic binders of the present invention include organic polymeric compounds, such as polyvinyls, polyacrylates, polymethacrylates, polyamides, polyesters, polyurethanes, polyethylene oxides, polypropylene oxides, and polyvinylalcohol.
  • Suitable monomers include organic compounds which are capable of dissolving the polymer.
  • the ceramic binders of the present invention can be prepared using common solution forming techniques. Typically, such methods include dissolving the polymer and monomer of choice in a suitable solvent by combining the solvent, monomer, and polymer system until a homogenous solution forms.
  • ceramic binder compositions of solutions of polymer, monomer, and solvent can be combined with ceramic raw materials and other additives which are typically used in ceramic fo ulations.
  • the resulting ceramic formulations are suitable for preparing ceramic articles using common processing techniques. After such articles are formed in the desired shape, they can be treated in a manner which causes the monomer in the binder to polymerize and fix the shaped article. This results in a green part having high strength and easy handling characteristics. When the green part is finally sintered to form the ceramic piece, the polymeric binder burns cleanly.
  • the present invention provides compositions comprising stable solutions of polymer, monomer and optionally, a solvent. Because the binder compositions of the present invention can be incorporated in ceramic formulations resulting in highly desirable tack and drape properties, the herein described compositions have particular utility in ceramic formulations for preparing continuous fiber reinforced ceramic matrix compositions and large sintered ceramic parts having intricate three dimensional characteristics. Those skilled in the art will appreciate, however, that the ceramic binder compositions of the present invention are not limited in their utility to the preparation of three dimensional advanced sintered ceramic parts, but can be used in fabricating all types of ceramics.
  • the present invention is based upon the discovery that stable solutions of polymer and monomer provide unexpectedly advantageous tack and drape characteristics to ceramic formulations.
  • Other attendant advantages include the ability to vary the tack and drape relative to the monomer-polymer ratio and the ability to adjust the cure time and temperature.
  • the ceramic binders include a stable solution of at least one organic polymer and at least one reactive organic monomer.
  • the organic polymer and the reactive organic monomer are present in amounts which result in the stable solution having solution viscosities of from about 20 cps to about
  • the ceramic binder composition also includes a solvent which contributes to the formation of a stable solution of polymer and monomer.
  • the polymer is present in the stable solution at from about
  • the monomer is present at from about 10 wt% to about 95 wt%.
  • a solvent is present it is generally present at from about 10 wt% to about 85 wt%.
  • the ceramic binder compositions of the present invention are stable solutions of from about 10 wt% to about 15 wt% of at least one organic polymer, from about 30 wt% to about 40 wt% of at least one reactive monomer, and from about 40 wt % to about 60 wt% solvent.
  • the combination of polymer, monomer and solvent has a viscosity of from about 20 cps to about 100 cps, as measured with a Brookfield viscometer using spindle #1 or #2. It is important to note that the compositions of the present invention are stable solutions and remain stable until activated. The stability is also characterized by prolonged shelf lives. This stability is achieved through careful selection of the combination of monomer/solvent such that the polymer of choice is soluble in the monomer, both of which are compatible with the solvent, if required. Because of the nature of chemical compounds and the thermodynamics of solutions, generally, like compounds dissolve like compounds. Accordingly, in most cases, the practice of the present invention results in compositions in which the monomer has similar chemical functionalities as the polymer. However, the compositions of the present invention are not necessarily limited to polymer and reactive monomers having the same or similar functionalities. Thus, compositions which include cosoluble polymers and reactive monomers having a variety of functionalities are considered within the scope of the present invention.
  • suitable polymers for incorporating into the ceramic binder compositions include, but are not limited to, soluble vinyl ester polymers such as polyacrylates and polymethacrylates, soluble polyamides, soluble polyvinyls, soluble polyesters, soluble polyamides, soluble polyethylene and soluble polypropylene oxides, polyvinyl alcohols, polyurethanes, epoxies, silicones, and phenolies.
  • soluble vinyl ester polymers such as polyacrylates and polymethacrylates
  • soluble polyamides such as polyacrylates and polymethacrylates
  • soluble polyamides such as polyacrylates and polymethacrylates
  • soluble polyamides such as polyacrylates and polymethacrylates
  • soluble polyamides such as polyacrylates and polymethacrylates
  • soluble polyamides such as polyacrylates and polymethacrylates
  • soluble polyamides such as polyacrylates and polymethacrylates
  • soluble polyamides such as polyacrylates and polymethacrylates
  • polyacrylates and polymethacrylates such as polymethylmethacrylate , polyethylaery1ate , polybutylmethacrylate, polybutylacrylate and similarly homologous acrylates and methacrylates.
  • polyacrylates and polymethacrylates such as polymethylmethacrylate , polyethylaery1ate , polybutylmethacrylate, polybutylacrylate and similarly homologous acrylates and methacrylates.
  • polyacrylates and polymethacrylates such as polymethylmethacrylate , polyethylaery1ate , polybutylmethacrylate, polybutylacrylate and similarly homologous acrylates and methacrylates.
  • suitable reactive monomers are those monomers which have good solvent characteristics or those monomers which when dissolved in a suitable solvent form soluble compositions with the polymer of choice.
  • the reactive monomer or combination of reactive monomers is liquid at ambient conditions, and the polymer of choice is soluble in the monomer.
  • monomers which are solid at ambient conditions can also be utilized provided the solvent utilized in the composition has a solubility for both the monomer and the polymer.
  • Monomers which have utility in the practice of the present invention include acrylates, methacrylates, acrylamides, vinyls and reactive vinyl terminated ester oligimers.
  • the vinyl esters such as methacrylates and acrylates are particularly suitable for use in the compositions of the present invention.
  • a wide variety of reactive vinyl esters are commercially available, and generally they are good solvents for many polymers. Additionally, the vinyl esters have good solubility in many organic solvents. Another advantage associated with the vinyl esters is their availability in functionalities higher than one. In this sense, functionality refers to the number of reactive vinyl function per molecule. As will be discussed below, by altering the number of functionality groups per molecule, both the viscosity of the binder composition and the physical properties of the cured green part can be controlled.
  • suitable solvents are preferably organic compounds which are liquid at ambient conditions.
  • the solvent selection is primarily controlled by the solvent solubility properties with respect to the polymer and monomer which are also incorporated in the compositions of this invention.
  • the solvent should not chemically react with the monomer. Likewise, the solvent should not interfere with the polymerization.
  • Organic solvents commonly used for dissolving polymers generally include ketones, esters, hydrocarbons, halogenated hydrocarbons, ethers, alcohols, carboxylic acids, and amides. Typically these solvents are limited to organic compounds having between 2 carbon atoms and 10 carbon atoms, however, the higher homologs are also considered to be useful in the compositions of the present invention.
  • solvent vapor pressure In addition to its solubility properties and the possibility of interactions with the monomer, another characteristic which can be considered when choosing a solvent is the solvent vapor pressure. Solvents having lower vapor pressures are advantageously utilized in situations in which it is important to retain the tack and drape characteristics of the ceramic formulation during the entire ceramic green part forming and handling process. Because the solvent is not readily evaporated from the part, the formulation handling characteristics are consistently the same for a longer length of time. Associated with the use of solvents having lower vapor pressures, however, is an increased difficulty in removing the solvent prior to the final sintering step. Accordingly, organic compounds having intermediate boiling points, typically less than 110 ⁇ C, are the preferable solvents.
  • Aqueous systems have found extensive utility in the field of ceramics and there are a number of monomers and polymers which are soluble in water. Moreover, water is a particularly suitable solvent from the standpoint of toxicity and handling considerations. While having a boiling point and vapor pressure intermediate in range, water has tendency to strongly absorb onto ceramic precursor compounds such as clays. For this reason, organic based solvents are preferred in the majority of 16 applications, even though water has many attributes which make it an attractive solvent.
  • compositions of the present invention are subject to thermal treatments at temperatures sufficiently high to burn out all organic materials.
  • certain types of organic compounds burn out more cleanly than others.
  • alkyl compounds will burn cleanly and leave minimal residue.
  • Aromatic and unsaturated compounds burn less cleanly and can leave a residue of unburned hydrocarbons. Therefore, preferred monomers and polymers are those which are unsaturated and have little or no aromatic functionality.
  • solvents having low vapor pressures are preferably alkyl solvents and not aromatic solvents.
  • the polymer, monomer, and solvent solutions additionally include an appropriate initiator or catalyst for polymerizing the monomer.
  • catalysts or initiators are preferably heat or light activated.
  • the ceramic binder compositions of the present invention can be stored in ambient conditions, and possibly away from light, for an extended length of time and still remain active.
  • Suitable initiators or catalysts depend upon the choice of reactive monomer and the type of chemical reactions which polymerize the monomer.
  • the monomer is a vinyl compound
  • peroxides are particularly suitable initiators. Many peroxides have long half lives at ambient conditions but decompose to products which initiate vinyl polymerization at elevated temperatures.
  • methacrylates or acrylates can be formulated with a peroxide such as benzoyl peroxide and stored in a nonreactive solvent for many months at ambient temperatures without polymerizing. If the temperature of the solution is sufficiently elevated the acrylate or methacrylate will polymerize.
  • a peroxide such as benzoyl peroxide
  • Other compounds which have application as a polymerization initiator are the peroxy decarbonates and bis azo which also decompose to products which initiate polymerization.
  • certain light sensitive compounds can be used as initiators in the binder compositions of the present invention. These compounds are stable in the dark or when exposed to certain ranges of light wavelengths. However, they will initiate vinyl polymerizations when exposed to certain electromagnetic wavelengths.
  • these initiators can be formulated with suitable vinyl reactive monomer and solvent and the solution will remain stable until it is exposed to light having the appropriate wavelengths. At this time the monomer will polymerize.
  • examples of such initiators are the benzoin type compounds.
  • the solution viscosity is a factor. Binder compositions having viscosities in the range of 100 cps or lower are preferable.
  • viscosities in the preferred range provide the ceramic formulation with superior tack and drape properties.
  • the solution viscosity is dependent upon a number of factors, but it can be controlled by selecting an appropriate polymer molecular weight, and choosing a solvent and polymer combination having solvent-solute interactions which result in the desired viscosity. Many common monomers have appropriate viscosities and these can provide the binder solution with preferred flow properties.
  • the preferred solution viscosity is from about 20 cps to 100 cps. However, solutions having viscosities of many thousand cps are also within the scope of the invention.
  • Stable solution combinations of acetone. polymethylmethacrylate, trimethylolpropanetrimethacrylate, and dicumyl peroxide are preferred for many applications because the tack and drape of ceramic formulations which include this binder composition are particularly favorable.
  • the monomer trimethylolpropane trimethacrylate is a trifunctional compound and forms a highly crosslinked polymer when polymerized, its solution properties are particular suitable for binder compositions. Additionally, this monomer has the preferred solution viscosity in small concentrations.
  • nonreactive solvents such as methylene chloride, methylethylketone, cyclohexanone, formamide, alcohol, 2- nitropropane, and N-methylpyrrolidinone can be substituted for the acetone.
  • polyvinylesters such as the series of polyalkylacrylates , and other polyalkylmethacrylates can be utilized in combination with or in place of the polymethylmethacrylate.
  • polyesters such as polymeric reaction products of organic acids and alcohols
  • monomers such as reactive polyester oligomers, solvent, and polymerization initiator or inhibitor combinations.
  • the reactive polyester oligomers include reactive vinyl terminated polyester oligomers which will polymerize to form polymers when appropriately initiated. Any stable solvent or solvent combination having solubility properties suitable for providing a solution having a viscosity from about 20 cps to about 60 cps is suitable in the polyester and reactive oligomer binder compositions of this invention.
  • Other examples of polymer, monomer, solvent, and initiator combinations which .
  • solutions having viscosities within ranges suitable as the binder compositions of the present invention are solutions of polyvinylchloride, cyclohexanone, a reactive vinyl monomer, and a peroxide. It is not necessary that, when polymerized, the monomer form interlocking compatible networks with the polymer utilized in the binder composition.
  • a variety of vinyl monomers, including vinyl esters, can be used in conjunction with polyvinylchloride.
  • the relative amounts of polymer, monomer, and solvent in the composition depend upon the desired viscosity and the solubility of polymer and monomer in the solvent.
  • the preferred binder compositions of the present invention contain about 10 wt% to 15 wt% of at least one organic polymer, about 30 wt% to about 40 wt% of at least one reactive monomer, and about 40 wt% to about 60 wt% solvent.
  • the solvent of choice has a high solubility for the polymer of choice so that higher amounts of polymer can be utilized. Solutions containing relatively large amounts of solvent and viscous monomers are preferred for the tack and drape properties they provide to ceramic formulations.
  • a preferred ceramic binder composition of the present invention is a solution comprising about 50 wt% acetone, about 37 wt% trimethylopropane trimethacrylate, about 12 wt% polymethylmethacrylate, and about 1 wt% dicumylperoxide.
  • the solution includes a polymer and monomer of like functionality, and the polymer is soluble in the monomer.
  • acetone the solvent of choice, has a high solubility for the polymer and monomer, and neither the polymer, monomer, nor the solvent is aromatic.
  • compositions and other ceramic binder compositions of the present invention can be prepared utilizing common polymer solution processing methods.
  • Such techniques include dissolving monomer and polymer in a solvent or combinations of solvents with stirring.
  • the polymer can be stirred and heated with the solvent and then cooled prior to adding monomer to the solution.
  • heat activated initiators such as organic peroxides
  • the process for forming the composition includes a heating step, if is preferable to cool the solution prior to adding the initiator. Accordingly, it is not likely that the monomer will prematurely polymerize, nor is it likely that the initiator will prematurely decompose.
  • light activated initiators it is important to avoid exposure to light within the sensitive wavelengths.
  • the ceramic binder compositions of the present invention have particular utility in ceramic formulations which are used to prepare green ceramic parts.
  • these binder compositions are combined with ceramic raw materials and other commonly used additives, the resulting ceramic formulation can be used to prepare large three dimensional ceramic parts using conventional forming techniques.
  • these ceramic formulations also can be used to prepare ceramic prepeg and fiber reinforced ceramics.
  • a process for fabricating ceramic parts includes the steps of providing a ceramic binder composition which includes a stable solution of at least one polymer, at least one reactive monomer and polymerization initiator.
  • the ceramic binder composition can optionally include a solvent which can advantageously be utilized to adjust the solution viscosity.
  • the next steps include combining ceramic raw material and the ceramic binder to form a ceramic formulation and then forming the ceramic formulation into shaped green ceramic parts. Thereafter, the part is treated to fix its shape and finally thermally treated to form a permanently shaped article.
  • any of the ceramic binder compositions described above can be used for fabricating ceramic parts according to the present invention.
  • Combining ceramic raw material and the ceramic binder composition is typically accomplished by mixing a ceramic raw material and other additives such as deflocculents with the ceramic binder composition to form a homogeneous ceramic formulation slurry.
  • the ceramic raw materials can be any of the solid ceramic precursors utilized in the ceramic industry such as clays, silica, and feldspar. Other nonclay minerals such as lime, gypsum, magnesium compounds, mullite, graphite, titania, alumina, zirconia, and specialized super refractories are also suitable.
  • Other ceramic raw materials which can be present in the ceramic formulaton include solvents and deflocculents.
  • a typical ceramic formulation includes from about 40 wt% to about 75 wt% alumina, from 0 wt% to about 20 wt% filler, from about 5 wt% to about 50 wt% solvent, from 0 wt% to about 3 wt% deflocculent, and from less than 1 wt% to about 3 wt% ceramic binder.
  • Forming the ceramic formulations into shaped green ceramic parts can be accomplished by conventional ceramic forming techniques. Suitable techniques include cold forming processes such as those utilized to lay up parts over a mold. Other techniques include extrusion, pultrusion and pressing methods. Casting methods in which cast sheets are prepared using doctor blades can also be successfully used to make green parts with the compositions of the present invention. Because the ceramic formulations utilized to prepare the green ceramic parts advantageously exhibit exceptional tack and drape properties, they are suitable for laying up ceramic parts over molds. Additionally, the tack and drape properties of the ceramic formulations allow the formation of large three dimensional and intricately shaped monolithic parts using plastic forming techniques rather than the more costly casting methods and reinfiltration methods which are normally required to make these parts.
  • the monomer is cured resulting in fixation of the desired shape.
  • the curing temperature will vary. Typically, however, the curing temperature is between about 149 ⁇ C and about 170°C.
  • the cure time depends upon the nature of the monomer, the initiator, and the part size, but typically requires from about 1 hour to about 8 hours.
  • treating the green ceramic part to cure the monomer can be accomplished by exposing the green part to high intensity light at a range of wavelengths which will initiate the monomer polymerization. This technique is suitable when the initiator in the binder composition is light sensitive as opposed to heat sensitive.
  • Sintering the cured ceramic part may be accomplished by known thermal treating methods.
  • the sintering temperatures and times at temperature are highly dependent upon the materials and the nature of the part.
  • the thermal treatment includes first heating the part at temperatures sufficient to burn out the ceramic binder. Generally, the temperature is less than about 480 ⁇ C. Then, the burned out part is exposed to higher temperatures ranging from about 500 ⁇ C to 2500 ° C to develop the final sintered ceramic product.
  • Example 1 A ceramic binder composition was prepared by adding 500 grams of acetone (available from Ashland Chemical Co.) to a liter size beaker fitted with an overhead stirrer. Then, 367 grams of trimethylolpropane trimethacrylate (available from Sartomer Company as Sartomer 350 Monomer) were added to the acetone, followed by the addition of 121 grams of polymethylmethacrylate (available from Rohm and Haas in the form of acrylic molding pellets) and 11 grams of dicumyl peroxide (available from Hercules as Dicup R) . The beaker was sealed with a cover designed to accommodate the overhead stirrer and the mixture of solvent, monomer, polymer, and initiator was stirred until the polymer, monomer, and initiator dissolved to form a stable solution.
  • acetone available from Ashland Chemical Co.
  • Example 2 A ceramic formulation was prepared by combining 700 grams of alumina (available from Alcoa as A-1000-5G) , 3 grams of deflocculent (available from Witco as EMPHOS PS21A) , 152 grams of clay filler (available from R.T. Vanderbuilt as Pyrax RG200) , 70 grams of acetone,and 230 grams of the binder prepared in Example 1. The combination was placed in a closed ball milling container and ball milled for 16 hours. Shaped green ceramic parts were fabricated from the ceramic formulation and then set by heating the green part to about 175°C. The resulting green parts exhibited high strength, and ease of handling due to good tack and drape characteristics. The cured ceramic part was sintered up to a temperature of 900°C for approximately 2 hours. The binder burned off cleanly and left little or no residue.
  • alumina available from Alcoa as A-1000-5G
  • deflocculent available from Witco as EMPHOS PS21A
  • clay filler available from R
  • Continuous fiber reinforced ceramic matrix composite was fabricated by passing lengths of alumina fibers through the ceramic formulation slurry prepared in Example 2 to form coated lengths of alumina fibers. After the fibers were drawn through the slurry, the combination of alumina fibers and ceramic formulation was approximately 50 wt% ceramic formulation and 50 wt% fiber. The coated lengths of alumina fibers were then used to form a green ceramic part using wet lay-up techniques. Following the lay-up procedure, the part was heated-at about 175°C. to cure the monomer. Then the part was sintered at a temperature of 900 ⁇ C to finally form the ceramic part.

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  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Health & Medical Sciences (AREA)
  • Polymerisation Methods In General (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Des compositions liantes pour céramique, utilisées dans des formulations céramiques pour mouler des pièces céramiques, sont décrites. Les compositions liantes se composent de solutions d'au moins un polymère, au moins un monomère réactif, un solvant et un produit d'amorçage. Lorsque les solutions liantes sont combinées à des matières céramiques brutes, les formulations céramiques produites obtiennent des caractéristiques d'adhérence et de drapage exceptionnelles, ce qui leur permet d'être utilisées pour le moulage de pièces en céramique à l'état vert en trois dimensions et de formes complexes. Les pièces en céramique à l'état vert peuvent être cuites selon des procédés de traitement polymère classiques et présentent une résistance améliorée.
PCT/US1992/005044 1991-06-18 1992-06-10 Compositions liantes polymeres pour ceramiques WO1992022509A1 (fr)

Applications Claiming Priority (2)

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US71670291A 1991-06-18 1991-06-18
US716,702 1991-06-18

Publications (1)

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WO1992022509A1 true WO1992022509A1 (fr) 1992-12-23

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AU (1) AU2258092A (fr)
CA (1) CA2111577A1 (fr)
WO (1) WO1992022509A1 (fr)

Cited By (6)

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Publication number Priority date Publication date Assignee Title
EP0662492A1 (fr) * 1993-12-28 1995-07-12 Nikkiso Co., Ltd. Panneaux résistants au feu, fixation et structures, en nid d'abeilles laminées en matérieu céramique renforcé par des fibres
EP0662491A1 (fr) * 1993-12-28 1995-07-12 Nikkiso Co., Ltd. Préimprégné, son procédé de production et produits ainsi obtenus
WO1995030631A1 (fr) * 1994-05-10 1995-11-16 Dytech Corporation Limited Production d'articles en ceramique
US5491181A (en) * 1993-07-29 1996-02-13 Bayer Aktiengesellschaft Themoplastic molding compounds
EP0765848A1 (fr) * 1995-09-29 1997-04-02 Rohm And Haas Company Méthode de mise en forme de pièces à partir d'un matériau inorganique pulvérulent
CN114262411A (zh) * 2022-02-14 2022-04-01 佛山市超速科技有限公司 一种新型复合高效陶瓷增强剂及其生产方法

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US4442258A (en) * 1979-07-04 1984-04-10 Nitto Electric Industrial Co., Ltd. Water-soluble pressure-sensitive adhesive composition
JPS62235308A (ja) * 1986-04-04 1987-10-15 Mitsui Toatsu Chem Inc セラミツクバインダ−用α−メチルスチレン共重合体組成物の製造方法
US4836966A (en) * 1984-03-15 1989-06-06 Isoo Shimuzu Binder for ceramics
US5028362A (en) * 1988-06-17 1991-07-02 Martin Marietta Energy Systems, Inc. Method for molding ceramic powders using a water-based gel casting

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4054517A (en) * 1974-08-06 1977-10-18 John Cunningham Chrome removal and recovery
US4442258A (en) * 1979-07-04 1984-04-10 Nitto Electric Industrial Co., Ltd. Water-soluble pressure-sensitive adhesive composition
US4836966A (en) * 1984-03-15 1989-06-06 Isoo Shimuzu Binder for ceramics
JPS62235308A (ja) * 1986-04-04 1987-10-15 Mitsui Toatsu Chem Inc セラミツクバインダ−用α−メチルスチレン共重合体組成物の製造方法
US5028362A (en) * 1988-06-17 1991-07-02 Martin Marietta Energy Systems, Inc. Method for molding ceramic powders using a water-based gel casting

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5491181A (en) * 1993-07-29 1996-02-13 Bayer Aktiengesellschaft Themoplastic molding compounds
EP0662492A1 (fr) * 1993-12-28 1995-07-12 Nikkiso Co., Ltd. Panneaux résistants au feu, fixation et structures, en nid d'abeilles laminées en matérieu céramique renforcé par des fibres
EP0662491A1 (fr) * 1993-12-28 1995-07-12 Nikkiso Co., Ltd. Préimprégné, son procédé de production et produits ainsi obtenus
US5512351A (en) * 1993-12-28 1996-04-30 Nikkiso Company Limited Prepreg, process for preparation of prepreg, and products derived therefrom
WO1995030631A1 (fr) * 1994-05-10 1995-11-16 Dytech Corporation Limited Production d'articles en ceramique
US5772953A (en) * 1994-05-10 1998-06-30 Dytech Corporation, Ltd. Production of ceramic articles
EP0765848A1 (fr) * 1995-09-29 1997-04-02 Rohm And Haas Company Méthode de mise en forme de pièces à partir d'un matériau inorganique pulvérulent
US5723083A (en) * 1995-09-29 1998-03-03 Rohm And Haas Company Method for forming parts from inorganic particulate material
AU719113B2 (en) * 1995-09-29 2000-05-04 Carpenter Technology Corporation Method for forming parts from inorganic particulate material
CN1080710C (zh) * 1995-09-29 2002-03-13 木工技术公司 由无机颗粒材料形成部件的方法
CN114262411A (zh) * 2022-02-14 2022-04-01 佛山市超速科技有限公司 一种新型复合高效陶瓷增强剂及其生产方法

Also Published As

Publication number Publication date
CA2111577A1 (fr) 1992-12-23
AU2258092A (en) 1993-01-12

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