USOO588O237A United States Patent (19) 11 Patent Number: 5,880,237 Howland et al. (45) Date of Patent: Mar. 9, 1999 54 PREPARATION AND UTILITY OF WATER- 4.885,345 12/1989 Fong. SOLUBLE POLYMERS HAVING PENDANT 5,071,933 12/1991 Muller et al.. DERIVATIZED AMIDE, ESTER OR ETHER 5,084.520 1/1992 Fong FUNCTIONALITIES AS CERAMICS 5,209,885 5/1993 Quadir et al.. 5,266.243 11/1993 Kneller et al.. DSPERSANTS AND BINDERS 5,358,911 10/1994 Moeggenborg et al.. 5,393,343 2/1995 Darwin et al.. 75 Inventors: Christopher P. Howland, St. Charles; 5,487,855 1/1996 Moeggenborg et al.. Kevin J. Moeggenborg. Naperville; 5,525,665 6/1996 Moeggenborg et al.. John D. Morris, Plainfield, all of Ill., 5,532,307 7/1996 Bogan. Peter E. Reed, Puyallup, Wash.; 5,567,353 10/1996 Bogan. Jiansheng Tang, Naperville, Ill., Jin-Shan Wang, Rochester, N.Y. FOREIGN PATENT DOCUMENTS O5009232 A2 1/1993 Japan. 73 Assignee: Nalco Chemical Company, Naperville, 05070212 A2 3/1993 Japan. III. 05294712 A2 11/1993 Japan. 06072759 A2 3/1994 Japan. 06313004 A2 11/1994 Japan. 21 Appl. No.: 982,590 07010943 A2 1/1995 Japan. 22 Filed: Dec. 4, 1997 07101778 A2 4/1995 Japan. 07133160 A2 5/1995 Japan. Related U.S. Application Data 07144970 A2 6/1995 Japan. Primary Examiner-Paul R. Michl 63 Continuation-in-part of Ser. No. 792,610, Jan. 31, 1997, Pat. Attorney, Agent, or Firm Elaine M. Ramesh; Thomas M. No. 5,726.267. Breininger (51) Int. Cl. ................................................ C08F 20/58 57 ABSTRACT 52 U.S. Cl. .................. ... 526/304; 526/307 58 Field of Search ...................................... 526/304, 307 Methods for dispersing and binding ceramic materials in aqueous media are disclosed. The methods utilize water 56) References Cited Soluble polymers having pendant derivatized amide, ester or U.S. PATENT DOCUMENTS ether functionalities for. dispersing and binding various classes of ceramic materials. 4,680,339 7/1987 Fong. 4,731,419 3/1988 Fong. 4 Claims, No Drawings 5,880,237 1 2 PREPARATION AND UTILITY OF WATER non-volatile Solid. The liquid is vaporized by direct contact SOLUBLE POLYMERS HAVING PENDANT with a drying medium, usually air, in an extremely short DERIVATIZED AMIDE, ESTER OR ETHER retention time, on the order of about 3 to about 30 seconds. FUNCTIONALITIES AS CERAMICS The primary controlling factors in a Spray drying proceSS are particle size, particle size distribution, particle shape, Slurry DISPERSANTS AND BINDERS density, Slurry Viscosity, temperature, residence time, and This application is a continuation-in-part of application product moisture. The viscosity of the slurry must be suitable for handling Ser. No. 08/792,610, filed Jan. 31, 1997 entitled “Prepara and Spray-drying. Although spray-drying equipment condi tion and Utility of Water-Soluble Polymers having Pendant tions may be adjusted to handle a variety of Viscosities, Derivatized Amide, Ester or Ether Functionalities as Ceram larger particles will usually result from higher Viscosity ics Dispersants and Binders”, now U.S. Pat. No. 5,726,267. Slurries. Those of ordinary skill in the art are familiar with the FIELD OF THE INVENTION Spray-drying proceSS used in the production of ceramic Methods for dispersing and binding ceramic materials in materials, and will be able to optimize the control factors of aqueous media are disclosed. The methods utilize water 15 Spray-drying to best advantage. Alternatively, the Spray Soluble polymers having pendant derivatized amide, ester or drying process may be replaced by other well known drying ether functionalities for dispersing and binding various methods, Such as granulation, tape casting and Slip casting. classes of ceramic materials. Spray drying of the slurry produces Substantially dry, free-flowing powder particles which contain the ceramic, the BACKGROUND OF THE INVENTION binder and the optional materials described above. The dry Ceramic materials are commonly prepared by mixing particles are granules which are generally Spheroidal in powdered ceramic oxides Such as magnesia, alumina, titania shape and have an effective diameter of about 50 to about and Zirconia, in a slurry along with additives, Such as 300 micrometers. Typically, about 0.5 percent to about 8 dispersants and binders. The Slurry may be spray dried to 25 percent of the binder, based on the dry weight of the ceramic produce ceramic particles. The particles are pressed into an powder, is present in the dry particles. aggregate structure, called a "green ceramic, having a In granulation, a mixture of dry powder or powderS is desired shape and Subsequently Subjected to a Severe heat mixed or rolled, commonly in a barrel shaped apparatus. treatment known as Sintering. The Sintering proceSS converts Water and/or a binder Solution is sprayed into the mixing the green ceramic into a cohesive “fired ceramic', having a powder causing aggregation of the Small particles into larger nearly monolithic polycrystalline ceramic phase. granules. The size of the granules is controlled by the The binder serves to hold the ceramic particles of the amount of material sprayed into the powders and the Speed green ceramic in the desired shape after pressing. The binder with which it is sprayed. Granulated powderS may be can also provide lubrication while the particles are pressed. Screened to a desired size and pressed to shape in a pressing Preferably, the binder combusts or vaporizes completely 35 operation prior to Sintering. Alternatively, the granules them during the Sintering proceSS leaving no trace of the binder in Selves may be the desired product and may be sintered the fired ceramic. In performing these functions, binders directly. Significantly affect the properties of the fired ceramics which Tape casting is commonly used to produce thin Substrates are ultimately produced. for the computer industry. In the process, a thick ceramic In commercial practice, poly(Vinyl alcohols) are widely 40 Slurry containing ceramic powder, dispersant and binderS is used as ceramic binders. Additionally, poly(ethylene oxide) prepared. This slurry is cast onto a Smooth Surface Such as and ethylene-Vinyl acetate copolymerS reportedly have been a Mylar or plastic sheet and the thickness is controlled by used as binders for particulate material, Such as granular passing the sheet under a blade which Smoothes the slurry Silica gel. Surface and Scrapes off exceSS material. The Slurry tape is 45 dried to a plastic State and cut and shaped to specification. For example, polymeric binders containing Substantially The amount of binders present in tape casting is very high, hydrolyzed copolymers made from monomers having ester typically on the order of 15 to 20 wt.% of the ceramic or amide functional groups, poly(Vinylformamide) or a powder mass. copolymer of vinyl alcohol and vinyl amine are disclosed in In fluidized bed spray drying, Small “Seed' particles are U.S. Pat. Nos. 5,358,911; 5.487,855 and 5,525,665. 50 placed in a column and hot air is blown into the Seed powder Furthermore, polymeric treatments have been disclosed in from below Suspending the particles in the column. A U.S. Pat. Nos. 4,680,339; 4,731,419; 4.885,345 and 5,084, ceramic slurry is sprayed onto the Seed particles from above, 520. Utility for the treatments has been disclosed to be as causing them to grow. When the particles reach a large dispersants in water treatment, Scale inhibitors in industrial enough size, they are siphoned out of the dryer while more and natural waters, flocculants, coagulants and thickeners, 55 Seed particles are introduced. This process can produce but ceramicS applications of binding and disperSancy have powder for further forming processes, or the powder itself not been disclosed. may represent the desired product, in which case it would be Although commercially available binders are Satisfactory Sintered to produce the final ceramic. for many applications, a need exists for improved binders The dry particles are compacted to produce an aggregate, which provide Still greater Strength and/or increased density 60 green ceramic structure. Preferably, the particles are com in green ceramic materials. Greater green Strength reduces pacted by pressing in dies having an internal Volume which breakage during handling of the green ceramics and, approximates the shape desired for the final fired ceramic generally, is associated with higher quality fired ceramics. product. Alternatively, the particles are compacted by roll Preferably, the improved binders would be cheaper and more compacting or other well-known compacting methods. The Versatile than previously known binders. 65 Spray dried blend of powder, binder, and optional Surfactants Spray drying is an evaporative process in which liquid is and lubricants is relatively free flowing So that it can enter removed from a slurry containing a liquid and a Substantially and closely conform to the shape of the pressing dies. 5,880,237 3 4 Inside the dies, the dry particles are Subjected to a to produce a fired ceramic material. Alternatively, the par pressure which is typically in the range of about 5000 to ticles can be formed into an aggregate, green ceramic about 50,000 psi. Pressing the particles produces an aggre Structure by roll compaction or other well-known methods. gate Structure, called a green ceramic, which retains its Although commercially available binders are Satisfactory shape after removal from the die. for many applications, a need exists for improved binders One forming technique used for Spray dried or granulated which provide Still greater Strength and/or high density in material is roll compaction, also referred to as roll pressing. green ceramic materials. Greater green Strength reduces This technique takes a dry powder and crushes it between breakage during handling of the green ceramics and, two rollers in a continuous process.