Actinic or electron beam radiation curable binder for ceramic materials

Abstract

Binder compositions for ceramics are described that include little or no organic solvents. The binder compositions exhibit excellent ceramic adhesion characteristics upon cure, while also exhibiting lower adhesion characteristics to other types of materials, e.g., polymeric backing materials. The binder compositions are based upon acrylate functionality, and include at least one acrylate functional monomer or oligomer.

Description

ACTINIC OR ELECTRON BEAM RADIATION CURABLE BINDER FOR CERAMIC MATERIALSCross Reference to Related Application

[0001] This application claims filing benefit of United States Provisional Patent Application Serial No. 63 / 491 ,163 having a filing date of March 20, 2023, which is incorporated herein by reference for all purposes.Background

[0002] Ceramic materials are used in a wide range of industrial applications ranging from electronics to structural material to 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. However, many formation processes require the utilization of a binder for temporarily or permanently adhering ceramic materials to one another. For instance, ceramic processing often involves formation of a slurry that includes a ceramic particulate and a binder in a composite mixture or slurry that is formable by molding, coating, or the like. The formed slurry is dried, such as by spray drying, thermal drying, or pan drying. In some formation techniques, the formed, dried composite forms a green article and the final product is formed by removal of the binder and sintering of the ceramic particulate at high temperatures.

[0003] A variety of polymeric binders have been utilized in the field of fabricating ceramic parts such as binders based upon waxes, starches, polyvinyl alcohol, gums, acrylates, celluloses, polyglycols, butyrals, epoxies and acetates. A good binder must satisfy several criteria. It should be soluble in the slurry containing the ceramic and it should have a low solution viscosity thereby permitting high solids content in the slurry and, when necessary, facilitate milling of the slurry. A good binder should also be compatible with other additives and processing steps. Moreover, in those embodiments in which the binder is present only in the green article, it should impart suitable strength to the green article and be completely removable during formation of the final product.

[0004] Unfortunately, most binder compositions include an organic solvent such as an alcohol (e.g., methanol, ethanol or isopropanol) or an aromatic organic solvent(e.g. , benzene, toluene, etc.). Removal of the organic solvent is a necessary step during dry / cure of the binder composition, but often involves formation of dangerous volatile organic compounds (VOC) at removal and thus requires expensive and time consuming processes such as utilization of vacuum at reduced pressures, off-gas scrubbing and recovery, and the like.

[0005] What is needed in the art is a binder composition for use with ceramics that includes little or no organic solvent. A low solvent binder composition that can provide excellent binding characteristics for ceramics while exhibiting only limited adhesion to other materials could be of great benefit in the art.Summary

[0006] According to one embodiment, disclosed is a binder composition. The binder composition includes an acrylate functional component. The acrylate functional component includes one or more acrylate functional monomers and / or one or more acrylate functional oligomers. Each molecule of the acrylate functional component including two or more acrylate functional groups. The binder composition includes about 5 wt.% or less organic solvents.

[0007] Also disclosed is a method for forming a ceramic article. A method can include contacting a ceramic material with a binder composition as described herein and then contacting the binder composition that is in contact with the ceramic material with actinic radiation, e.g., radiation in the ultra-violet spectrum or electron beam radiation, upon which the binder composition can be cured and adhere to the ceramic material.Brief Description of the Figures

[0008] A full and enabling disclosure of the present subject matter, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures in which:

[0009] FIG. 1 illustrates a binder sample as described herein following cure.

[0010] FIG. 2 illustrates another binder sample as described herein following cure.

[0011] FIG. 3 illustrates another binder sample as described herein following cure.

[0012] FIG. 4 illustrates a ceramic coating sample as described herein following binder burnout.Detailed Description

[0013] Reference will now be made in detail to various embodiments of the disclosed subject matter, one or more examples of which are set forth below. Each embodiment is provided by way of explanation of the subject matter, not limitation thereof. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present disclosure without departing from the scope or spirit of the subject matter. For instance, features illustrated or described as part of one embodiment, may be used in another embodiment to yield a still further embodiment.

[0014] In general, the present disclosure is directed to binder compositions that include little or no organic solvents for use with ceramic materials. The binder compositions can exhibit excellent ceramic adhesion characteristics upon cure, while also exhibiting lower adhesion characteristics to other types of materials, e.g., polymeric materials. As such, disclosed binders can be utilized in one embodiment in formation of ceramic materials on backing substrates that are intended for removal during use, e.g., releasable polymer backing sheets or the like.

[0015] Disclosed binder compositions can exhibit a low viscosity. For instance, a binder composition can exhibit a viscosity as determined by use of a Brookfield™ viscometer using a #21 spindle at 100 rpm at 22 °C of about 7000 centipoise (cps) or less, such as about 3000 cps or less, or about 2000 cps or less in some embodiments. For example, a binder composition can exhibit a viscosity of from about 20 cps to about 4000 cps, or from about 40 cps to about 1000 cps, in some embodiments. A binder composition can exhibit a slip viscosity as determined by use of a Brookfield™ Cone and Plate #4 plate, 200 sec-1of from about 600 cps to about 6500 cps, such as from about 650 cps to about 3000 cps in some embodiments.

[0016] A binder composition can also exhibit low shrinkage upon cure. Shrinkage can be determined by density change from liquid to solid as measured by using an Anton Parr™ gas pycnometer Ultrapyc 5000) for cured material and density cup (BYK 2007787, 8.32 ml_, 1.0% Tolerance) for a liquid material. For instance, a binder composition can exhibit a shrinkage upon cure of about 10% or less, such as about 8% or less or about 6% or less in some embodiments. For example, a binder composition can exhibit shrinkage upon cure of from about 1 % to about 10%, from about 2% to about 8%, or from about 2.5% to about 7%, in some embodiments. Thelow shrinkage values of the binder compositions can prevent structural changes (e.g., warping, cracking, etc.) to materials during cure, e.g., during formation of a green article.

[0017] The glass transition temperature of a cured binder composition as determined according to dynamic mechanical analysis can generally be about -30°C or higher, such as about -20°C or higher, such as from about -30°C to about 70°C, from about -30°C to about 50°C, from about -20°C to about 40°C, or from about - 20°C to about 40°C in some embodiments.

[0018] Disclosed binder compositions can also exhibit desirable mechanical properties. For instance, following cure, disclosed binder compositions can exhibit an elongation at break as determined by a film fixture using a Starrett™ Instron Model FLC-500 set at 1 inch / min with sample dimensions of 1 inch X 4 inch X 0.005 inch of from about 3% to about 65%, or from about 5% to about 60% in some embodiments. A cured binder composition can exhibit a tensile strength at break as determined by using a Starrett™ Instron Model FLC-500 set at 1 inch / min with sample dimensions of 1 inch X 4 inch X 0.005 inch of from about 20 psi to about 2500 psi, such as from about 25 psi to about 2300 psi, or from about 200 psi to about 400 psi in some embodiments. A cured binder composition can exhibit a maximum storage modulus as determined by using a TA Instruments™ DMA 850 using a film tension clamp (rectangular geometry: length ca 12-16mm, width 6-7mm, thickness 0.100 to 0.200mm, amplitude 10.0um, 1 Hz Frequency, preload force 0.01 N, temperature ranges from -60C to 150C, heating rate 3-5 deg / min), from about 100 MPa to about 4000 MPa, such as from about 150 MPa to about 3500 MPa, or from about 500 MPa to about 3000 MPa in some embodiments. A cured binder composition can exhibit a loss modulus as determined by using a TA Instruments™ DMA 850 using a film tension clamp as a temperature sweep at constant Hz from about 40 MPa to about 500 MPa, such as from about 45 MPa to about 475 MPa, or from about 50 MPa to about 475 MPa in some embodiments.

[0019] A binder composition as disclosed herein can include little or no organic solvents. For instance, a binder composition can include about 5 wt.% or less organic solvents, such as about 4 wt.% or less, about 3 wt.% or less, or about 2 wt.% or less in some embodiments. As utilized herein, the term “organic solvent” refers to any carbon-based substance capable of dissolving or dispersing another substance. Examples of organic solvents include, without limitation, acetone, ethyl acetate,hexane, heptane, dichloromethane, methanol, ethanol, tetrahydrofuran, acetonitrile, dimethylformamide, toluene, benzene, and dimethylsulfoxide.

[0020] A binder as disclosed herein includes an acrylate functional component. The acrylate functional component can include one or more acrylate functional monomers and / or one or more acrylate functional oligomers. Each molecule of the acrylate functional component of the binder incorporates two or more acrylate functional groups, i.e., difunctional, trifunctional, or higher acrylate functionality on each component of the acrylate functional component such that the acrylate functional monomer or oligomer is at least bifunctional with regard to the acrylate functionality. In general, the acrylate functional component can constitute about 75 wt.% or more of the binder composition, such as about 78 wt.% or more, about 80 wt.% or more, about 85 wt.% or more, about 90 wt.% or more, or about 95 wt.% or more in some embodiments.

[0021] As utilized herein, the term “oligomer’ generally refers to a polymer having relatively few repeating units and having a number average molecular weight of about 150,000 g / mol or less, such as about from about 7,000 to about 110,000, or from about 10,000 to about 100,000, or from about 10,000 to about 50,000, or from about 15,000 to about 40,000 in some embodiments.

[0022] In one embodiment, an acrylate functional oligomer can include a polyester acrylate, e.g., an aliphatic polyester acrylate and / or an aromatic polyester acrylate. In one embodiment, an acrylate functional monomer or oligomer can include a urethane acrylate, which can encompass aliphatic urethane acrylates and / or aromatic urethane acrylates, e.g., a polyurethane acrylate. In one embodiment, an acrylate functional oligomer can include a polyester urethane acrylate.

[0023] Acrylate functional monomers and oligomers as may be included in a binder composition can include, without limitation, acrylate monomers, urethane acrylate monomers, polyurethane acrylates, polyester acrylates, polyether acrylates, isocyanate-terminated acrylate monomers or oligomers, epoxy acrylates, acrylate esters, and any combination thereof. For instance, a binder composition can include one or more of, and without limitation to, tripropylene glycol diacrylate, ethylene glycol diacrylate, isobornyl acrylate, ethylhexyl acrylate (e.g., 2-ethylhexyl acrylate), propoxylated tetrahydrofurfurl acrylate, 4-tertbutylcyclohexyl acrylate, aliphatic or aromatic polyester acrylates (e.g., difunctional and / or trifunctional polyesteracrylates), aliphatic or aromatic polyester urethane acrylates, aromatic urethane acrylates, difunctional and / or trifunctional urethane acrylates, and mixtures thereof.

[0024] Acrylate functional monomers and oligomers as may be incorporated in a binder composition are available in the market, such as from the Rahn Corporation under the tradename Genomer™ and from Sartomer Americas. By way of example, specific examples of acrylate functional monomers and oligomers encompassed herein can include, without limitation, aliphatic polyester urethane acrylate oligomer (e.g., Genomer™ 4316 available from Rahn USA Corp.), aromatic urethane acrylate (e.g., Genomer™ 4622 available from Rahn USA Corp.), trifunctional polyester acrylate (e.g., CN2264 available from Arkema Sartomer® Americas), polyester acrylate oligomers (e.g., CN2282, CN292, CN2273 available from Arkema Sartomer® Americas), difunctional hydrophobic urethane acrylates (e.g., BRC843S, available from Bomar™), isobornyl acrylate (e.g., Genomer™ 1121 Y available from Rahn USA Corp.), tertbuylcyclohexyl acrylate (e.g., Genomer™ 1119 available from Rahn USA Corp.), acrylate ester (e.g., SR9045 available from Arkema Sartomer® Americas), and any combination thereof.

[0025] In one embodiment, a binder composition can include one or more acrylate functional monomers, e.g., a mixture of two or more acrylate functional monomers, optionally in conjunction with one or more additional multifunctional monomers including acrylate-reactive functionality such as, without limitation, amide, acrylonitrile, vinyl styrene, or butadiene functionality, or any combination thereof.

[0026] In one embodiment, a binder composition can include at least one acrylate functional oligomer in conjunction with one or more multifunctional monomers that includes non-acrylate functionality that is reactive with the acrylate functionality of the oligomer, e.g., as a crosslinking agent for the acrylate functional oligomer. For instance, a binder composition can include one or more acrylate functional oligomers (e.g., a polyester acrylate, a polyester urethane acrylate, or a mixture thereof) in conjunction with one or more multifunctional monomers including reactive functionality including, without limitation, amide, acrylonitrile, vinyl styrene, butadiene reactive functionality, or a combination thereof.

[0027] In one embodiment, one or more monomers of a binder composition can include acrylate functionality in conjunction with one or more acrylate oligomers as well as one or more multi-functional monomers or oligomers that includes functionality that is reactive with acrylate functionality. For example, a bindercomposition can include a polyester acrylate oligomer and / or a polyester urethane acrylate oligomer as well as one more acrylate functional monomers, optionally in conjunction with one or more multi-functional monomers that includes a different (non-acrylate) functionality. Moreover, a component that includes a non-acrylate functionality (e.g., amide functionality) can optionally include acrylate functionality in addition to the non-acrylate functionality.

[0028] When present, monomers and / or oligomers that include acrylate reactive functionality (other than acrylate functionality) can generally constitute about 20 wt.% or less of a binder composition.

[0029] In one embodiment, a binder composition can also include a dispersant.In general, a dispersant can constitute about 20 wt.% or less of the binder composition, such as from about 5 wt.% to about 20 wt.% of the binder composition, such as from about 8 wt.% to about 17 wt.%, or from about 10 wt.% to about 15 wt.% in some embodiments.

[0030] Dispersants suitable for a binder composition can include materials based on a polymeric polyester / polyamine condensate. Examples of such dispersants include those that are commercially available under the tradename Solsperse® 28000 Of course, dispersants of a binder composition are not limited to such, and other dispersants as are known in the art are encompassed herein, including, and without limitation to, esters of fish oils or surfactants, acrylic polymers, polyvinylpyridine or polyvinyl butadiene

[0031] In one embodiment, a binder composition can include a cure system. For example, a binder composition can include one or more substances that act as a cure initiator to encourage curing (e.g., crosslinking) of components of the composition upon interaction with actinic radiation and / or electron beam radiation. As utilized herein, the term “actinic radiation” is intended to refer to electromagnetic radiation that is capable of producing photochemical effects. For instance, the binder composition can be cured by actinic radiation in the ultraviolet (UV) or visible spectrum, both of which can encompass actinic radiation.

[0032] In one embodiment, a cure system can include a photoinitiator. When present, a photoinitiator can constitute about 15 wt.% or less of the binder composition, such as about 12 wt.% or less, such as from about 2 wt.% to about 10 wt.% in some embodiments.

[0033] In one embodiment, a photoinitiator can be configured to initiate cure upon interaction with light in the UV spectrum (about 100 nm to about 400 nm wavelength). Suitable UV light can include that emitted from a UV light source as is known in the art. UV light from any conventionally known source may be used in accordance with such an embodiment. By way of example, a UV light source can include a microwave energized light source, a medium pressure mercury vapor UV light source, an amalgam low pressure UV light source, or an LED UV light source that can emit at one or more useful wavelengths, e.g., 385 nm, 395 nm, 405 nm, or any band that encompasses UV wavelengths capable of initiating cure. Upon cure, a photoinitiator can bond, e.g., polymerize with, a component of the mixture, e.g., the ceramic constituent and / or an oligomeric or monomer component. For instance, a photoinitiator can bind or otherwise adhere to ceramic particles upon cure.

[0034] In one embodiment, a photoinitiator may include one or more of, and without limitation to, a benzoin compound, an acetophenone compound, an acylphosphine oxide compound, a titanocene compound, a thioxanthone compound, a phenyl propanone, or a photosensitizer such as an amine, a butanone, or a quinone, or any combination thereof. Exemplary photoinitiators can include, without limitation, benzophenone, hydroxyacetophenone, methylbenzophenone, 4- phenylbenzophenone, 4,4'-bis(diethyl amino)benzophenone, 4,4'- bis(dimethylamino)benzophenone (Michler’s ketone), 4-(2-hydroxyethoxy)phenyl-(2- hydroxy-2-methylpropyl)ketone, 1 -hydroxycyclohexyl phenyl ketone, benzyldimethyl ketal, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1 butanone; 2- dimethylamino-2-(4-methyl-benzyl)-1 (4-morpholin- 4-yl-phenyl)-butan-1-one, 2- mercaptobenzoxazole, camphorquinone, 2-hydroxy-2-methyl-1-(4-t- butyl)phenylpropan-1 -none, 2-methyl-1 -[4-(methylthiophenyl)-2-morholinopropanone, 2-hydroxy-methyl-1 -phenyl propanone, maleimides, 2,4,5-trimethylbenzoly-diphenyl phosphine oxides, bis(2,6-dimethyloxybenzoyl) 2,4,4-trimethylpentyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide, polymeric photoinitiators derived from the above, and any combination thereof. In one embodiment, a mixed photoinitiator may be utilized such as a blend of about 70 wt. % oligo(2-hydroxy-2- methyl-1-[4-(1-methylvinyl)phenyl]propanone and about 30 wt. % 2-hydroxy-2- methyl-1-phenylpropan-1-one, commercially available from Lamberti USA, Inc., Conshohocken, Pa. under the trade name Esacure™ KIP 150 or KIP 100F. Other photoinitiators sold by Lamberti USA, Inc. under the KIP or Esacure™ designationmay also be utilized, such as Esacure™ SM 303. Other polymeric photoinitiators include PL-816A from Palermo Lundahl Industries and those available under the tradename Omnirad™ such as Omnirad™ 379 available from IGM Resins. In one embodiment, an oxide photoinitiator may be utilized. Examples of suitable oxide photoinitiators can include bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide commercially available from Ciba Specialty Chemicals, Tarrytown, N.Y. under the trade name Irgacure™ 819 Additional examples of suitable photoinitiators include, without limitation, 1 -hydroxycyclohexyl phenyl ketone available under the trade name Irgacure™ 184, and 2-hydroxy-methyl-1 -phenyl propanone under the trade name Irgacure™ 1173. Other photoinitiators sold by Ciba Specialty Chemicals under the Irgacure™ trade name are also suitable for use.

[0035] In one embodiment, the system need not include a photoinitiator. By way of example, in one embodiment a binder composition can be cured by utilizing an electron beam radiation, which can initiate polymerization as the accelerated electrons cleave bonds of one or more components of the composition, thereby creating radicals for polymerization initiation and instigating polymerization propagation and formation of a polymer backbone. For example, a binder composition can be cured by contact with electron beam radiation of about 100 kV potential or greater.

[0036] In one embodiment, a cure system can include a thermal initiator. In one embodiment, a cure system can include both a thermal initiator and a photoinitiator, in which case the thermal initiator may facilitate UV curing of the binder composition. In one embodiment, a thermal initiator can include a free radical initiator that generates radicals upon exposure to suitable temperature. When present, a thermal initiator can generally constitute about 10 wt.% or less of a binder composition, such as about 8 wt.% or less, or about 5 wt.% or less in some embodiments, such as from about 1 wt.% to about 5 wt.%.

[0037] Examples of thermal initiators can include, without limitation, peroxide compounds (e.g., a benzoyl peroxide), azo compounds (e.g., azo compounds sold under the Vazo™ tradename), or any combination thereof. Specific examples of thermal initiators encompassed herein can include, without limitation, 2,2'-azobis(2- methylbutane nitrile (Vazo™ 67), 2,2'-azobis(isobutyronitrile) (Vazo™64), (2,2 - azobis(2,4-dimethylpentanenitrile) (Vazo™ 52), 1 ,1 '-azobis(cyclohexanecarbonitrile) (Vazo™ 88), 4,4'-Azobis(4-cyanovaleric Acid) (Vazo™ 56 WSP) 4,4-Azobis(4-cyanopentanecarboxylic Acid), and 4 , 4'-( 1 ,2-Diazenediyl)bis[14-cyanopentanoic Acid (Vazo™68 WSP), among others.

[0038] A binder composition can include other components as are known in the art. By way of example, a binder composition can in one embodiment include a pore former, i.e., a sacrificial material that can be removed during processing or after formation of a ceramic component and, upon removal, creates voids (pores) within the ceramic material and / or the binder. For instance, a pore former can decompose upon heat treatment, or through contact with water or other solvent that does not dissolve or unfavorably affect the ceramic material. A pore former can be removed by any suitable process including, without limitation, evaporation, sublimation, or during firing. For instance, a pore former can be removed during a heating phase of a sintering process, prior to a sintering process, or following a sintering process.

[0039] In one embodiment, a pore former can include ionic salts. Ionic salts have a relatively high boiling and melting point and thus can maintain structure through processing until desired dissolution. Moreover, ionic salts can be formed to a wide range of particle size. Ionic salt pore forming agents can be removed by dissolving in water, and the dissolution process can be enhanced at elevated temperature. Other types of pore forming agents can include, without limitation, graphite, starch, foamed resins, water-absorbent resins, and silica gel. When utilized, a single type of pore former may be used, or a plurality of types of pore formers may be used. When present, a pore former can generally constitute from about 0.5 to about 10 parts by mass by 100 parts of the final porous material. For instance, in formation of a porous ceramic material, the pore former can constitute from about 0.5 to about 10 parts by mass per 100 parts by mass of the ceramic.

[0040] A binder composition can exhibit excellent binding characteristics with any type of ceramic in any form. As utilized herein, the term “ceramic” is generally intended to refer to any of a variety of hard, brittle, heat- and corrosion-resistant materials that include at least one metallic element (which may include silicon) in combination with oxygen, carbon, nitrogen, or sulfur or a combination thereof. Moreover, a ceramic for use with disclosed binding compositions may be crystalline or polycrystalline.

[0041] By way of example, and without limitations, exemplary ceramics can include aluminas (e.g., aluminum oxide (AI2O3), aluminum oxide hydroxide, etc.), aluminum nitrides, silicon oxides (e.g., silicas), silicon carbides, titanium oxides (e.g.,titanium dioxides), titanium nitrides, magnesium oxides, boron nitrides, silicon nitrides, zirconium oxides, zirconium nitrides, doped ceramics, or any combination thereof. Particular examples of ceramic materials can include, without limitation, black silicon carbide, green silicon carbide, titanium diboride, boron carbide, tungsten carbide, titanium carbide, cubic boron nitride, garnet (e.g., lithium garnets such as lithium lanthanide zirconium oxides (LLZO) including Li?La3Zr20i2 (LLZ), Lii.3Alo3Tii.?(P04)3 (LATP), etc.), fused alumina zirconia, sol-gel derived ceramics (e.g., alumina ceramics doped with chromia, ceria, zirconia, titania, silica, and / or tin oxide), silica (e.g., quartz, glass beads, glass bubbles and glass fibers), feldspar, spinel, flint, or any combination thereof.

[0042] In one embodiment, the ceramic can be in the form of a particulate. For instance, a binder composition can be mixed with a ceramic particulate to provide a slurry that can be formed (e.g., cast, molded, etc.). Upon cure of the binder, e.g., upon exposure to actinic radiation, a green article can be formed.

[0043] In general, a binder composition as described herein can constitute from about 10 wt.% to about 60 wt.% of a slurry, with solids (e.g., a ceramic particulate and any pore forming materials) constituting from about 40% to about 90% of a slurry.

[0044] A slurry that incorporates a binder composition and a particulate that includes a ceramic can be mixed by using known methods and devices.

[0045] In some embodiments, a slurry including a binder composition can be further processed prior to forming. For instance, a slurry can be milled to provide the solid particulate of the slurry at a desired size with few or no agglomerates in the slurry.

[0046] A binder composition can exhibit stronger adherence to a ceramic than to other materials after cure, e.g., polymeric materials. For instance, one or more components of the binder composition can adhere to a polymeric backing material, but with lower adhesion characteristics as compared to the adhesion to a ceramic material. By way of example, a photoinitiator of a composition can bond to a polymeric backing material upon exposure to UV radiation and cure of the binder, however, the overall adhesion of the binder to the backing material will be relatively weak as compared to the adhesion to the ceramic material. As such, disclosed binder compositions can be particularly beneficial for use in applications in which a ceramic material is formed on a backing substrate that is intended for removal duringprocessing, e.g., after formation of a green article and prior to final sintering. Backing materials as are known in the art can be utilized with a binder composition, e.g., cloth or paper, or a polymer, e.g., polyethylene, polytetrafluoroethylene, polyethylene terephthalate (Mylar™), a metal foil, etc.

[0047] As the cured binder composition exhibits stronger adhesion to ceramic than to other materials, a backing sheet can be easily removed from a green article, leaving the ceramic green article in the desired form and without any green-state slippage.

[0048] The present invention may be better understood with reference to the examples set forth below.Example 1

[0049] Binder composition samples were formed as described in Table 1 , below. Contents are provided as weight percentages, unless otherwise noted. The UV cured binder composition samples illustrate the effect of glass transition temperatures (Tg) on flatness of green state ceramic / binder composites following cure and prior to burn out.Table 1

[0050] A slurry was prepared with each binder composition sample by mixing 4g of a binder composition with 16g of a ceramic particulate (LLZO). Mixing was performed using a ‘SpeedMixer’ set to 2300 rpm for 3 min. with a ceramic ball. Thefinal mixed slurry was smooth and uniform with no sign of air entrapment. The slurry was further milled in a 3 roll mill and applied to a polyester sheet to an even thickness of 50-70 pm.

[0051] Following coating, the binder composition of each coated material was UV cured by passing the coated sheet under an Xtrema™ Plus UV unit available from Miltec UV at 20 feet per minute. The UV data used in all examples was determined by use of a radiometer and is provided in Table 2, below.Table 2

[0052] Table 3, below, presents physical characteristics of the binder composition alone as well as characteristics of the composite including the binder composition mixed with the ceramic particulate prior to UV cure, following UV cure, and following burnout.

[0053] Shrinkage was determined by density change from liquid to solid as measured by using an Anton Parr™ gas pycnometer Ultrapyc 5000) for cured material and density cup (BYK 2007787, 8.32 mL, 1.0% Tolerance) for the liquid portion. Percent shrinkage was calculated using the formula:Shrinkage = (1- (liquid density (g / mL) / cured density (g / mL)) x 100.

[0054] Flatness of the materials was determined after UV cure of the binder of the coated slurry and again after burnout (180° for 1 hour). To evaluate the flatness of the products, a ranking scale was developed. Rankings were as follows:5 - all 4 corners were flat with no apparent major curl4 - one edge corner was lifted3 - 2 or 3 edge corners were lifted2 - all 4 corners were lifted1 - the sample was rolled

[0055] Viscosity was determined by use of a Brookfield™ RVT (serial # 8669793) viscometer using a #21 spindle at 10Orpm. Slip viscosity was determined by use of a Brookfield™ Cone and Plate CAP2000-L (serial # 8702324) #4 plate, 200 sec-1 . Glass transition temperatures (Tg) were obtained by dynamic mechanical analysis(DMA) unless otherwise noted. The characteristics for the binder / ceramic composite include slip viscosity as determined by use of a cone and plate and flatness determined as described above in Table 2 after UV cure and again after 180°C burnout for one hour.Table 3

[0056] As seen, the Tgvalues range from -19°C to 30°C where the higher the Tgthe better the lay down was observed for green state UV cured slips. Samples 1 and 3 showed the effect of Tgon degree of flatness of the ‘green state' UV cured binder / ceramic composite. The Tgof Sample 1 was found to be -19°C and this sample did not lay flat after UV cure (FIG. 1) compared to Sample 4, which was found to have a Tgfor the UV binder of 30°C and laid flat after UV cure (FIG. 2).Example 2

[0057] Binder samples were formed as described in Table 4, below. The effect of urethane acrylate type on performance properties was investigated while keeping other component amounts constant in formation of Samples 5 and 6. For Sample 7, a trifunctional polyester acrylate was utilized rather than a urethane acrylate.Table 4

[0058] A slurry was prepared with each binder sample by mixing 4g of binder with 16g of a ceramic particulate (LLZO). The slurry was applied to a substrate and cured under UV as described above. Burnout of the cured material was carried out at 180°C for 1 hour. Physical properties of samples, including properties of UV cured binder samples alone and ceram ic / binder composites prior to UV cure, following UV cure, and following burnout were determined as described above and are provided in Table 5, below.Table 5

[0059] As seen, the change in urethane acrylate type resulted in a lower shrinkage UV binder from 6.5% for sample 5 to 3.3% for sample 6. Utilization of a trifunctional polyester acrylate in place of the urethane acrylate also provided a binder with good performance properties including good flatness after UV cure and burn out at 180°C.Example 3

[0060] Binder samples were formed as described in Table 6, below. In these samples, the effect of the polyester oligomer Tgon performance was investigated where the Tgof the oligomers ranged from -45°C to 26°C. Tgfor the higher temperature Tgmaterial was obtained via either DMA or differential scanning calorimetry (DSC), as shown.Table 6

[0061] A slurry was prepared with each binder sample by mixing 4g of binder with 16g of a ceramic particulate (LLZO). The slurry was applied to a substrate and cured under UV as described above. Burnout of the cured binder was carried out at180°C for 1 hour. Physical properties of the samples were determined as described above and are provided in Table 7, below.Table 7

[0062] Flatness of Sample 9 is illustrated following binder cure in FIG. 3 and following binder burnout in FIG. 4. As shown, in both states, the composite was nearly flat.Example 4

[0063] Binder samples were formed as described in Table 8, below. Table 8 also includes Sample 1 , described previously for comparison. In samples 11 and 12 a thermal radical initiator was utilized in conjunction with a traditional UV photoinitiator.Table 8

[0064] A slurry was prepared with each binder sample by mixing 4g of binder with 16g of a ceramic particulate (LLZO). The slurry was applied to a substrate and cured under UV as described above. Burnout of the cured binder was carried out at 180°C for 1 hour. Physical properties of the samples were determined as described above and are provided in Table 9, below.Table 9

[0065] As shown, the green strength of the UV cured binder / ceramic slurry exhibited improved excellent green strength as evidence by flatness after cure. Lower viscosities were also observed by incorporating the thermal radical initiator.Example 5

[0066] Binder sample no. 13 was formed as described in T able 10, below.Characteristics of Sample no. 13 re shown in Table 11 . The tables also include data of Sample 1 , described previously. As indicated, in sample 13, removal of theTPGDA with substitution of a multifunctional polyester acrylate was found to improve ‘Green Curl’ vs. Sample no. 1.Table 10Table 11Example 6

[0067] Binder samples were formed as described in Table 12, below without dispersant. In these samples, a masterbatch was combined with one of three different photoinitiators, including a phenyl propanone photoinitiator (PI-1), a phenyl ketone photoinitiator (PI-2), or a butanone photoinitiator (PI-3). Amounts are provided in grams unless otherwise specified.Table 12

[0068] A slurry was prepared with each binder sample by mixing 3g of binder with 17 g of a ceramic particulate (LLZO). Mixing was performed using a ‘SpeedMixer’ set to 2300 rpm for 3 min. with a ceramic ball. The mixing was repeated a second time. The warm slurry was applied with a K coater using a 70 pm wwr on the silicone face of a Mylar™ substrate and immediately UV cured using a D bulb, 20 fpm, 100% power emitting UVA (2106 mJ / cm2; 4647 mW / cm2), UVB (555 mJ / cm2; 1457 mW / cm2), UVC (91 mJ / cm2; 272 mW / cm2), UVA (2003 mJ / cm2; 4444 mW / cm2).

[0069] A 4” X 4” template was used to razor cut sections of the cured coated substrate. The release properties of the UV cured ceramic green layer were evaluated by placing a Tong Depressor with a tape with a 4 inch edge with overhang of by % inch. The tape edge was placed on one edge of the 4” X 4” cured ceramic layer and pulled slowly at a 45-degree angle to the substrate surface to release the ceramic layer from the underlying substrate. The release properties were evaluated by the following criteria: 1) complete removal of 4”X 4” ceramic layer with no tearswas a PASS. 2) Any tears in the ceramic layer, due to not releasing, that occurred while pulling the ceramic layer from the underlying substrate was a FAIL. This test was performed initially after formation and at 3 hrs. following formation.

[0070] All samples were found to Pass at the ‘Initial’ time test. At the 3 hr. test, Sample 16, which included the butanone photoinitiator passed.

[0071] While certain embodiments of the disclosed subject matter have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the subject matter.

Claims

WHAT IS CLAIMED IS:

1. A curable binder composition for use with a ceramic comprising: an acrylate functional component, the acrylate functional component comprising one or more acrylate functional monomers and / or one or more acrylate functional oligomers, each molecule of the acrylate functional component comprising two or more acrylate functional groups; wherein the curable binder composition comprises about 5 wt.% or less organic solvents.

2. The curable binder composition of claim 1 , further comprising one or more of a photoinitiator and a dispersant, and optionally comprising a thermal initiator in conjunction with a photoinitiator, for instance wherein the photoinitiator constitutes about 15 wt.% or less of the curable binder composition and / or wherein the dispersant constitutes about 20 wt.% or less of the curable binder composition.

3. The curable binder composition of claim 1 or claim 2, wherein the acrylate functional component constitutes about 75 wt.% or more of the curable binder composition.

4. The curable binder composition of any of the preceding claims, wherein the acrylate functional component comprises an acrylate functional oligomer such as a polyester acrylate or a polyurethane acrylate, and / or wherein the acrylate functional component comprises one or more acrylate functional monomers.

5. The curable binder composition of any of the preceding claims, further comprising a multifunctional monomer comprising amide functionality, acrylonitrile functionality, vinyl styrene functionality, butadiene functionality, or a combination thereof.

6. The curable binder composition of any of the preceding claims, wherein the curable binder composition exhibits a viscosity as determined by use of a viscometer using a #21 spindle at 100 rpm at 21 °C of about 7000 centipoise or less.

7. The curable binder composition of any of the preceding claims, wherein upon cure, the cured binder composition exhibits at least one of the following characteristics: a shrinkage of about 10% or less, an elongation at break of from about 3% to about 65%, a tensile strength of from about 20 psi to about 2500 psi, a max storage modulus of from about 100 MPa to about 4000 MPa, a loss modulus of from about 40 MPa to about 500 MPa, or a glass transition temperature as determined according to a dynamic mechanical analysis of about -30°C or higher.

8. A method for forming a ceramic article comprising: contacting a ceramic material with a curable binder composition, the curable binder composition comprising an acrylate functional component that includes one or more acrylate functional monomers and / or one or more acrylate functional oligomers, each molecule of the acrylate functional component comprising two or more acrylate functional groups, wherein the curable binder composition comprises about 5 wt.% or less organic solvents; and irradiating the curable binder composition with electromagnetic radiation while it is in contact with the ceramic material and thereby curing the binder composition and adhering the cured binder composition to the ceramic material.

9. The method of claim 8, wherein the ceramic material comprises a ceramic particulate, the step of contacting the ceramic material with the curable binder composition forming a slurry, the method further comprising sintering the ceramic particulate following the step of curing the binder composition.

10. The method of claim 9, further comprising prior to cure of the binder composition, applying the slurry to a surface of a backing substrate.11 . The method of claim 9 or claim 10, further comprising including a pore former in the slurry, the method further comprising decomposing the pore former following cure of the binder composition.

12. The method of any of claims 8 through 11 , wherein the curable binder composition comprises a photoinitiator or a dispersant.

13. The method of any of claims 8 through 12, wherein the electromagnetic radiation comprises electron beam radiation or wherein the electromagnetic radiation comprises UV radiation.

14. A ceramic article formed according to a method of any of claims 8 through 13.

15. A ceramic article according to claim 14, wherein the ceramic article is in the form of a sheet comprising four or more corners, and wherein following the step of curing the binder composition, the sheet exhibits curling or lifting of no more than three of the corners.

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