Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09G—POLISHING COMPOSITIONS; SKI WAXES
  • C09G1/00—Polishing compositions
  • C09G1/02—Polishing compositions containing abrasives or grinding agents
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M103/00—Lubricating compositions characterised by the base-material being an inorganic material
  • C10M103/06—Metal compounds

Definitions

• the present invention relates to sol or gel particles alone or within a liquid media as a suspension medium. More particularly there is provided a carrier system that possesses long term dispersion stability characteristics for particle suspensions, referred to herein as soft-settle properties, which have uses with a large range of inert particles that can be suspended including abrasive, non-abrasive, inert solid organic particles, ceramic particles, which may be used for lapping applications, wire saw cutting, chemical mechanical polishing and/or planarization in metal forming and finishing, free abrasive grinding, and the like.
• Non-aqueous, semi-aqueous and aqueous suspensions of non-colloidal high density abrasive particles have been previously used in wire saw cutting and lapping of wafers, but have been unsuccessful in obtaining a stable slurry suspension of particles capable of maintaining the separation of the inert particles within the suspension over time.
• U.S. Patent No. 5,099,820 issued to Stricot discloses an abrasive slurry of a suspension of silicon carbide particles in water or oil.
• the suspensions are not stable and do not provide uniform lubrication and cutting by the wires.
• Such compositions require vigorous agitation to maintain a uniform suspension of particles, and the suspensions settle out quickly under stagnant conditions even during work-piece slicing while still under agitation.
• U.S. Patent 6,602,834 to Ward, et al. discloses a non-aqueous or semi-aqueous cutting and lubricating composition for use with wire saws that relies upon a surfactant, an organic polyelectrolyte and pH to provide electrostatic repulsion and particle-to-particle interference to maintain a stable suspension of abrasive particles.
• U.S. Patent 6,054,422 to Ward, et al. which is also incorporated herein by reference, discloses a lubricating composition containing up to 70 weight percent abrasive grit material in a suspension utilizing a mixture of high and low molecular weight polyalkylene glycols as a suspension agent.
• wafers are cut from larger ingots, bricks, boules, etc.
• the next step following the initial cut of the wafer, disc, piece, etc. involves the LAPPING of the cut wafer to smooth out the surface, lower the Total Thickness Variation (TTV) which is not applicable to Solar wafers, eliminate damage depth defects, and prepare the wafer for final POLISHING, i.e., primarily applicable to semiconductor and optical wafer production.
• aqueous carriers are used as the suspension media for the lapping abrasives employed in this step.
• Lapping abrasives can include, but are not limited to: SiC, Aluminum oxides, Zr0 2 , Silicas, Ce0 2 , diamond, etc.
• Lapping slurries utilize abrasive particles that are in the size range of about 0.1-10 pm.
• suspended abrasive particles are typically non-colloidal in size and nature. This does not exclude the use of colloidal lapping abrasive, i.e., abrasive particles of size range from about 0.001-0.5 pm, but such particles are not typically used in lapping slurries.
• the lapping slurry for wafers, mechanical gear sets for the auto industry, ceramics, etc. is subjected to many shear, grinding, and abrasive forces during the wafer lapping process.
• the slurry is injected onto the wafer surface, which is held between two large metal, e.g., typically iron and/or steel, plates.
• Counter rotation of the upper and lower plates holding the wafer compresses the slurry between the upper plate and the wafer surface.
• the solids within the compressed slurry contact the wafer and angular momentum causes the abrasive action to remove surface wafer defects and "etch" away the desired amount of wafer surface material.
• Aqueous suspension of non-colloidal, i.e., NCOL, high-density abrasive particles has been a severe and debilitating problem for "wafer" manufacturers for several decades.
• NCOL non-colloidal, i.e., high-density abrasive particles
• the abrasive particles begin to agglomerate and quickly settle out of suspension at the bottom of the container as a very hard "concrete like” cake.
• Such abrasive particle settling in presently utilized "aqueous" slurries occurs quickly, even during constant mixing or recirculation.
• These stable slurry suspensions can be used in wire saw applications for the cutting of ingots or other large materials into wafers, discs, or other machined, sliced, ground, or formed pieces; for lapping applications, CMP applications, machining, grinding and milling applications; for automotive metal gear formation applications, optical and opto-electronic slicing, grinding and lapping applications, and in the separation of particles.
• non-aqueous gel particles are preferably comprised of polyacrylic acid, polymaleic acid, polyalkylacrylic acids, or co-polymers thereof that are neutralized or partially neutralized in-situ within an organic medium, preferably polyethylene glycol, polypropylene glycol, diethylene glycol, or other suitable glycols to create a typical gel- particle species within the formation medium that meets the same performance suspension properties of other gel-particles.
• the gel particles formed in a non-aqueous medium also contain the typical characteristics of gel-particles that are created in-situ within the suspension medium of use or as a "gel-particle" formation medium from which the formed gel-particle is transferred to a second suitable medium for inert or abrasive particle suspension; provided that, the second medium does not react, interact, affect or reduce the suspension performance of the "gel-particle" within the final chosen medium.
• a further object of the invention is to provide a means for suspending colloidal or NCOL abrasive or other particles in a liquid not depending upon final slurry viscosity.
• Another object of the invention is to provide gel particles which can be added to a variety of base carriers for separating and suspending inert particles and also act as lubricants. It is a yet further object of the present invention to provide an aqueous or semi-aqueous carrier/slurry system that will not cause corrosion of metals such as iron, carbon steel, etc.
• the present invention relates to the suspension of particles in a carrier and to sol-gels or gel particles which can be used alone or in an organic or aqueous medium to suspend solid inert particles.
• Gel particles that include sol-gels, gel particles, gelatinous precipitates, etc., (hereinafter "gel particles") are used to suspend inert particles and to act as lubricants in a variety of applications as particles alone or in a liquid medium.
• the suspension slurry composition formed can contain gel particles in amounts ranging from about 0.1 % up to about 60% of the carrier by weight.
• the gel particles and base carrier may be used without the addition of other suspended particles as a lubricant.
• the aqueous content of the carrier can contain about 1 to 100% by weight of water with an organic solvent added for any carrier less than 100% water.
• the organic medium can comprise a variety of solvents, preferably alkylene and polyalkylene glycols, depending upon use which is inert and non-reactive with the aqueous medium and the suspending "gel-particles" which include the abrasive material being suspended by the gel-particles.
• the suspending gel particles have a density similar to or somewhat greater than the carrier-solvent composition.
• the gel particles which are preferably aluminum hydroxide; (AI(OH) 3 ), magnesium hydroxide; Mg(OH) 2 , zinc hydroxide; Zn(OH) 2 , copper hydroxide; Cu(OH) 2 , and the like for in- situ aqueous formation and suspension usage, can be created in an aqueous or aqueous- based medium, separated and transferred to a second medium, whether aqueous or nonaqueous, or used alone in a variety of cases.
• the gel particles may be required as a lubricant or to custom formulate a suspension or slurry of stable suspended abrasive or non-abrasive particles that will be referred to collectively as slurries.
• gel particles can be formed with other metal sulfides, hydroxides, and oxide hydrates that can form a suspended precipitate in water within a pH range between 3 and 12.
• the invention includes the method for the suspension of inert colloidal or non-colloidal abrasive or non-abrasive inert particles in a stable aqueous, semi aqueous or organic carrier medium.
• the carrier medium forms the liquid in which suspending particles are in-situ formed so as to establish an appropriate concentration of suspending particles to inert particles to produce sufficient interference to settling of said inert particles in said carrier medium.
• the carrier medium comprises a range from 0.1 to 60 % by weight of the suspending particles, which differ from said inert particles, selected from the group consisting of alkaline earth metal and transition metal hydroxides, oxy hydroxides, and oxide hydrates that are used to form in- situ said suspending particles within and inclusive of said carrier medium at a pH between 4 and 12.
• the in situ formation of the suspending particles in the carrier medium results in the suspending particles exhibiting a set of substantially uniform properties of having distinctly different molecular, configurational, rheological and physical structures than the carrier medium, a density greater than that of the carrier medium, visually identifiable and separate physical structure than the carrier medium, measureable size differences in a range between approximately 2-3 ⁇ and 500 pm, and containing molecules of the carrier medium within which the suspending particle was formed, but without any further chemical reaction with the carrier medium, though an interaction between the gel-particle structure and the internally contained carrier molecules is both possible and probable.
• the suspending particles exhibit these properties independent of their formation mechanism or origin of components.
• the inert particles are suspended in the carrier medium by at least one of physical interference between the suspending particles and the inert particles, attracting forces between the suspending particles and the inert particles to provide a proximity for chemical, physical or physicochemical interference, and electrostatic charge repulsion of the suspending particles from the inert particles and themselves, all to prevent agglomeration and coagulation of said inert particles in said carrier medium over an extended period of time.
• suspending particles which can be gel particles, sol-gel particles or gelatinous precipitates of a number of chemical compounds, are described in greater detail below.
• the suspending particles may be formed in a separate medium from the final carrier medium.
• the present invention provides a means for providing a broad variety of gel particles formed or originated under a large diversity of conditions from many different compounds, polymers, and materials where the "in-situ" formation of the gel particles are under a broad and different set of formation conditions, component material compositions, and variable in-situ formation media spanning organic, inorganic and semi-organic matrices providing a stable suspension of inert or abrasive particles in an aqueous, semi-aqueous or organic medium, without agglomeration or particle hard settling utilizing sol-gels or gel particles, and for the express purpose of cutting, slicing, machining, grinding, milling, lapping, re-shaping, preparing finished pieces of hard materials into finished pieces such as, but not limited to wafers, discs, specialty hard metal, semi-metal, or ceramic parts from larger hard material pieces by the use of a stable cutting, slicing, grinding, etc. slurry made stable by virtue of the unique "stability properties" of the gel
• suspension and/or lubricating carriers and slurry compositions for wire saw applications such as cutting or slicing slurries, lubricants, lapping or polishing slurries, non-abrasive slurries, and the like in which a suspension of particles is maintained at ambient as well as elevated temperatures.
• the gel particles are maintained as an aqueous, semi-aqueous, or non-aqueous suspension in about 0.1 to 80 weight percent of the carrier medium which provides for sufficient particle-to-particle interference against agglomeration or hard settling of the abrasive or inert particle with a "gel- particle" density somewhat greater than the density of the carrier medium.
• the gel particles can be prepared separately and then used alone or in a carrier as a lubricant and/or suspension agent or combined with an appropriate polar or non-polar solvent depending upon the suspension compatibility of the gel-particle with the carrier medium.
• the gel particles can advantageously be used in different types of glycols so that the lubricating compositions can be custom made for a particular use.
• the particles to be suspended may have different densities and/or electrostatic charges from the suspending gel particles. For example, in wire saw cutting operations there are cutting particles and kerf particles from the ingot being cut. In other operations there can be contaminants with higher density or similar density as the suspending medium.
• suspending particles for the aqueous example case, are in situ formed alkaline earth metal or transition metal hydroxides, oxy-hydroxides, and oxide hydrates (also referred to as hydrous oxides) that form a suspended particulate precipitate, i.e., sol-gels, gel particles, gelatinous precipitates, etc., in aqueous or semi-aqueous media at a pH in a range from about 3 to 12.
• the particles to be suspended comprise the conventional abrasive or non-abrasive particles, inert particles having a particle size of about 1 to 100 ⁇ for pigment manufacture, wire saw cutting, metal finishing applications and smaller size for wafer lapping applications being in the range typically of about 0.1 to 10 pm, and even lower for CMP applications, the particles being the range of about 10-500 nm.
• the preferred suspending particles are those formed in situ or separately such as when a metal salt is formed into the metal hydroxide. In such a case, the density of the in-situ prepared precipitated gelatinous "gel particles" is greater and the surface area of the gel particle formed in-situ is typically less than "dried" commercially available forms, if such forms are available at all.
• the in-situ formed gel particles usually will retain a higher density than the in-situ carrier medium, or any second medium wherein the formed "gel particles" are placed.
• the abrasive material for use in the above-recited composition may include powders of diamond, silica, tungsten carbide, silicon carbide, boron carbide, silicon nitride, silicon dioxide, cerium oxide, zirconium oxide, aluminum oxide, or other hard grit "powder" material.
• mean or average particle sizes range from about 0.5-100 microns and preferably from about 2- 50 microns, or a mixture thereof.
• concentrations of the inert particles being suspended in the suspension medium or carrier for most applications typically may range from about 0.1 to 60 weight percent of the total suspension.
• Solvents which may be used with aqueous media are polar solvents which include alcohols, amides, esters, ethers, ketones, glycols, glycol ethers, alkyl lactones, or sulfoxides.
• polar solvents are dimethyl sulfoxide (DMSO), dimethylacetamide (DMAC), N-methyl pyrrolidone (NMP), (gamma) ⁇ -butyrolactone, diethylene glycol ethyl ether, dipropylene glycol methyl ether, tripropylene glycol monomethyl ether, various glycols, polyethylene glycols and polypropylene glycols, and the like.
• the organic solvents are used in some cases to provide needed viscosity levels to the resulting slurries being prepared. Other uses for organic solvents may include a lowering of the slurry/carrier freezing point.
• the choice of the solvent is relatively immaterial as long as the solvent is inert, fully miscible or soluble in water, for the case of aqueous formed gel-particles, non-reactive with water or with the suspended particles or suspending gel particles, and has low toxicity and is of low odor.
• the suspending particles in the aqueous formed gel-particle case include, but are not limited to, metal hydroxides, oxide hydrates (or hydrous oxides) and oxides other than the abrasive particles that form an aqueous or semi-aqueous suspension, i.e., gel particles, gelatinous precipitates, sol-gels, colloidal or non-colloidal suspensions, etc.
• These suspending particles as an important component of the present invention, may settle down toward the bottom of the container over time, but will not settle out over time to form a hard agglomerate or particle "cake" on the container bottom.
• An insoluble fully suspended gelatinous precipitate or precipitates of aluminum are formed with a pH ranging between about 4 and 12.
• suitable metal hydroxides of use for the aqueous formed gel-particle example of this invention include, but are not limited to copper hydroxide, aluminum hydroxide, barium hydroxide, ferrous or ferric hydroxide and Zn(OH) 2 .
• metal sulfides, salts or oxide hydrates which may be used to form, or form in-situ the suspending particles in the aqueous example of this invention are transition metal oxides such as Zn-salts, ZnS, Sn0 2 xH 2 0, tin-salts, SnS, AI 2 0 3 xH 2 0, Al-salts, and the like.
• salts, sulfides, oxy- hydroxides, oxide hydrates (or hydrous oxides), and the like can also be used to form the corresponding hydroxides to provide a stable suspension medium that includes sol-gels, gel particles, and gelatinous particles suspension for the aqueous carrier system example of this invention.
• a pH range for use in the carrier is about 3-12.
• a preferred pH range is 5-10 and the most preferred pH range is 6-9.
• suspending precipitates or gel-particles include those particles having a density greater than that of the carrier solvent, and those that are naturally precipitous or suspendable. It is understood that there are those metal oxy-hydroxides, hydroxides or hydrous oxides which have a higher density except when formed or precipitated in-situ in the aqueous or semi- aqueous medium which is then added to the carrier systems of this invention.
• SSR soft-settle retention characteristics
• SVR suspension volume retention
• a slurry containing 15 - 25% silicon carbide (SiC) JIS 1000 grade i.e., an average particle size between approximately 13-16 m, was prepared and stored in 50 mL graduated tubes with a conical bottom at ambient and 50°C with both the SSR and SVR measured over an extended period of time.
• SiC silicon carbide
• the soft-settle retention characteristic was measured using an IMADA Vertical Manual Lever Force Test Stand, Model LV-100.
• the IMADA measures the force required for a probe with a standard diameter circular pad at the shaft bottom to pass through the slurry and reach the bottom of the container.
• the set up of the IMADA was modified by lengthening the probe shaft so that the probe could extend into and reach a point within 1 mm of the conical bottom of the graduated tube; that bottom having a diameter less than 1 mm greater than the diameter of the circular probe bottom.
• the probe was lengthened by attaching an elongated threaded rod to the probe.
• the force measured by the IMADA is reported in hundredths of pounds.
• a low SSR indicates that the abrasive can be easily re-suspended, and a high value such as greater than 1 .0 indicates that the abrasive has hard settled and cannot be easily re-suspended.
• the suspension volume retention [SVR] is calculated by measuring the volume of the solid occupied within the tube in mL, dividing that volume by the overall volume of the slurry in the graduated tube in mL, and multiplying the result by 100 for a percentage reading.
• SVR the higher the SVR value, i.e., the closer to 100%, the better the ability of the carrier to hold the abrasive in suspension.
• the SVR of a slurry generally decreases over time, but is not necessarily indicative of the soft-settle characteristics of the slurry. On an irregular basis, the SVR reading will not coincide with expected values under the conditions of the "soft-settle" experiment for the slurry under study.
• SVR may be a qualitative indicator, it does not provide consistent values expected for a "soft-settled” slurry in contrast to the far more accurate, consistent and quantitative soft settle characteristics [SSR] values. Therefore, SVR is often, but not always indicative, but is not a quantitative criteria, as SSR is, of the overall stability of the slurry.
• An ostensibly non-aqueous "gel-particle” suspension carrier was formed in-situ within PEG-200 in the following manner.
• the suspension gel-particles were formed by the partial neutralization of a co-polymer of acrylic acid and maleic acid with a final molecular weight of >3000D.
• Said polymer was initially purchased as a 50/50 (wt/wt) aqueous solution, and added to the suspension carrier, PEG-200, where a clear to slightly cloudy "solution" of the co-polymer acid was made.
• This polymer acid was partially neutralized using an amino-hydroxide base until the proper "gel-particles" were formed within the PEG suspension medium at a concentration sufficient to suspend -48% SiC abrasive on a wt / wt. basis.
• the slurry was used to cut many Si ingots into wafers, after which the slurry became “exhausted” and was stored within 300 gal. 4' x 4' x 4' containers with a total weight exceeding 3000 lbs. per container.
• the spent slurry was "cold stored” in an environment without temperature and/or humidity control in a stagnant mode for 4 years.
• a 5' long steel shaft with a circular disc at the shaft end with a diameter of ⁇ 8" an oversized IMADA rod
• the "soft- settle” characteristics of the long-term stored spent slurry was qualitatively measured by slowly dropping the "IMADA rod” without any external force downward into the slurry within each container to qualitatively determine the hardness of the settled solids. SVR for these solids was measured to be ⁇ 30%.
• the IMADA rod successfully dropped to the very bottom of the slurry within the containers without any external force, demonstrating an SSR of ⁇ 0 even after 4 years of stagnant storage.
• the lower the SSR for a given slurry over time the more stable, uniform, and better the slurry with respect to performance, stable storage capacity, prevention of coagulated or agglomerated solids over time, slurry suspension maintenance, and recyclability and ease of original slurry suspension characteristics after long storage times.
• the invention relates to aqueous, non-aqueous and semi-aqueous media
• extended contact of formulations of this invention with metals such as carbon steel, iron, spring steel, etc. that are typical components of wire saws, metal finishing lappers, wafer lappers, etc.
• metals such as carbon steel, iron, spring steel, etc. that are typical components of wire saws, metal finishing lappers, wafer lappers, etc.
• a corrosion inhibitor may be added to the carrier formulations of the present invention to suppress or eliminate metal corrosion when required.
• Appropriate inhibitors should not cause foaming, interfere with the formulations' ability to provide long-term stable abrasive or solids suspensions, or compromise the viscosity, rheology, or uniformity of the carrier formulations and their associated abrasive or solids suspensions.
• Suitable corrosion inhibitors which may be added to the aqueous and semi-aqueous carriers of the present invention may include, but are not limited to, aliphatic and aromatic carboxylic acids, neutralized carboxylic acids using alkanol amines (i.e., diethanol amine, mono-ethanol amine, etc.), tetra-alkylammonium hydroxides, other similar non-metal hydroxide bases, alkyl or aromatic amines, or other Bronsted bases. Also included may be other metal corrosion inhibitors known in the art such as long chain modified carboxy!ates commercially available under such trade names as DeForest DeCore-APCI-95, DeTrope CA-100.
• corrosion inhibitors equally suitable for the corrosion prevention or suppression of metals used in CMP processes (i.e., Al/Cu, Cu, Al/Si, Al/Si/Cu, GaAs, LnP, and the like) may include but are not limited to benzoic acid, pyrogallol, gallic acid, ammonium thiosulfate, 8-hydroxy quinoline, catechol, benzotrizole, triethanolamine, imadazoles (ie; such as benzimidazole and alkyl-substituted benzimidazoles, et.
• benzoic acid pyrogallol, gallic acid, ammonium thiosulfate, 8-hydroxy quinoline, catechol, benzotrizole, triethanolamine, imadazoles (ie; such as benzimidazole and alkyl-substituted benzimidazoles, et.
• thiophene compounds such as Sulfolane, modified polyacrylic acids or polyacrylates, polysaccharides, polyalcohols such as polyvinyl alcohol, etc., or combinations thereof.
• suitable corrosion inhibitors which function as oxygen absorbers or scavengers which include but are not limited to p-hydroquinone (i.e., p-quinol), polyhydroxy aromatics such as catechol or gallic acid, 8- hydroxyquinoline, nitrites, sulfites, ascorbic acid, etc.
• the selection of the corrosion inhibitors for the purpose of this invention is immaterial as long as the inhibitor meets the above mentioned performance criteria including: • suppress or eliminate metal corrosion;
• Certain of the salts which are generated as a by-product of the reaction to form the gel particles may appropriately increase the ionic strength so as to aid in the repulsion and increase the settling time of the suspended inert particles given the right concentration and structure of said generated salt.
• the SSR reading for the Ti02 solids suspended slurry of "zero" demonstrates an excellent suspension.
• the ambient SVR reading of 42% at the end of four weeks with an SSR value at all measured points of "0" is consistent with a well “soft-settled” suspension.
• the SVR though indicative of a stable "soft-settled” slurry does not produce the quantitative or qualitative readings expected, that is "... though the SVR may be a qualitative indicator, it does not provide the consistent values expected for a "soft-settled” slurry ... .”
• Solid aluminum sulfate octadecahydrate was added to tap water so that the concentration of aluminum sulfate in water was 15.54%. This solution was neutralized with KOH (25% solution in water) to a pH of 7.7. Added to this white cloudy carrier system is 48% by weight of SiC particles of average size -8-9.5 ⁇ . The entire suspended slurry is mixed thoroughly for ⁇ 5 min.
• the formulation, viscosity, SSR, and SVR data are listed in the following tables.
• Inert salts may be added to provide additional electrostatic repulsion of particles. Also, dissolved salt created by the gel particle formation may be rinsed out with water or the appropriate carrier medium solvent to create a gel particle suspension with comparatively little or no ionic character.
• the gel-particles were separated from the in-situ water medium, and then added to DEG to provide a "gel-particle" suspension appropriate for the suspension of a lapping abrasive.
• the SSR, SVR and viscosities were measured.
• the soft-settle measurement tubes were prepared with 18% zirconium oxide (Zr0 2 ) instead of SiC. The measurement results are provided in the following Tables 4a-1 and 4a-2.
• the purpose of the following formulations is to lower the viscosity of the formulation described in Example 4a by diluting the carrier with tap water.
• the carrier was diluted 25% and 50% with water, keeping the concentration of aluminum sulfate constant between various dilutions. For this example, 50% dilution is reported in the Tables below.
• the soft-settle tubes were prepared with 18% zirconium oxide (Zr0 2 ) instead of SiC. The measurement results are provide in Tables 4c- 1 and 4c-2.
• the SSR results in Table 4c-2 demonstrate a minimally acceptable reading for soft-settle properties of the ambient temperature slurry when the percent aluminum sulfate content used to form the "AI(OH) 3 " in-situ gel particles in aqueous medium is greater than about 0.75%.
• the SSR indicates a stable soft-settle slurry after one week when the percent aluminum sulfate content is greater than 0.50%.
• the separated gel particles prepared in accordance with Example 2, Step A were combined with enough PEG200 to yield a wet gel-particle concentration of ⁇ 30% wt/wt. To this is added sufficient water to dilute the carrier suspension by 25%, 50% and 75% to provide three different gel particle concentrations between the three different dilutions.
• SSR and SVR the variation in overall pH, SSR and SVR is reported in Table 5 below. 18% zirconium oxide (Zr0 2 ) was added to the mixture consistent with other examples herein, and slurry properties measured. The measurement results of the various dilutions are listed in the following table.
• the gel particles that are being described are essentially malleable or gelatinous particles that are formed in-situ within a suspending medium, or may be formed outside the final suspending medium, but is mixed, exposed, or otherwise directly interacts with the suspending medium such that a physico-chemical reaction, absorption interaction, electrostatic interaction or other "combining" mechanism between the formed gel particle and the suspending medium takes place to form the final gelatinous, malleable particle that becomes suspended within said medium.
• a gel particle is not considered to be an emulsion, sol, or gel. It is a distinct "gelatinous" particle that actually contains within it some of the molecules of the liquid medium from which it was formed using any of the above or other mechanisms to form the gelatinous particle.
• the gel particle is partially solid, but not a suspended liquid as in the case of emulsions. Gel particles for the purpose of this invention will have common properties regardless of the differences in actual gel particle chemistry or the mechanism by which it was formed.
• the gel-particle is a separate and distinct molecular and physical structure having different properties that are separate and independent of the overall medium within which it was formed by whatever means employed, implemented or used to form the "gel particle".
• Gel particles may be formed in very different suspension or carrier mediums using compounds, polymers, oligomers, organic or inorganic materials that have no other similar characteristics between them other than those properties that are typical to the resulting formed "gel particles”.
• the gel particles are prepared using similar methods
• the gel particles are prepared "in-situ" within their suspending medium; c) the gel particles are created as a separate and distinct molecular environment existing within the very different molecular environment of the medium from which they were created;
• the gel particles have densities that are somewhat greater than the densities of the mediums within which they were formed;
• the gel particles efficiently and effectively suspend inert particles by means of physical interference, density differences, electrostatic charge contributions (in repulsion) and gel-particle-to-inert particle interactions, such as mechanical, secondary (i.e., inter- and intra-molecular charge distribution effects (dipole forces), hydrogen bonding forces or Van der Walls forces) resulting in attachment and/or physicochemical particle interference;
• the gel particles are prepared by chemical interaction or chemical reaction with another molecule within the separate and distinct "in-situ" medium within which they are formed.
• gel-particles regardless of what medium they are formed in, or just what components form the final gel-particles, also have very similar and distinct characteristics or properties from other forms of matter, which include the following:
• the gel particles are always formed in-situ within a carrier medium of distinctly different molecular, configurational, rheological and physical properties than the gel-particle itself.
• the gel particles have densities that are always somewhat greater than the medium from which they were formed, since they contain part of that medium within their structure and will tend to settle down toward the bottom of the container over time.
• the formed gel particles are distinctly separate environments, i.e., physically, configurationally, structurally and visibly, from the medium from which they were formed.
• the gel particles have measurable sizes and are separate physical entities from the carrier medium within which they are formed and suspended.
• the gel particles are malleable, "soft" and flexible entities, and can be mechanically adhered to other inert particles within the suspending medium forming a sort of cushion around an inert particle serving to increase that inert particle's capacity for suspension within the medium.
• the gel particles contain molecules of the carrier medium from which they were formed within the gel-particle itself.
• gel particles can vary greatly in their physical structure and size from ⁇ 2-3 ⁇ to 500 ⁇ , or perhaps even larger depending on the size of the molecular or polymeric components from which they are prepared.
• the formed gel particles are not emulsions, sols, gels, or soluble particles, although they contain molecules of the carrier medium within them, they are distinct, semi-gelatinous particles that are completely separate and distinct entities and environments from the carrier medium. Once formed, the gel particle is no longer reactive with the medium from which it was formed. It does contain molecules of the carrier within it, but there is no further chemical reaction with the carrier medium.
• gel particles of invention are not emulsions, nor do they have the properties of emulsions by definition, they are considered to be "semi-solid" particles that share properties of solid particles, gels and emulsions together. However, they do not fit into any one of these categories of matter.
• Gel-particles as suspending particles, primarily exist only under conditions where they are kept “wet” with the carrier molecules within the particle maintained intact. If dried, or allowed to "evaporate” or have the carrier medium molecules removed from the gel-particle, the suspension features of the particle will fail and the "dried” particle will cease to exhibit any abrasive or inert particle suspension properties.
• gel particles that will satisfy the characteristics and properties of the present invention.
• These potential gel particle materials fall into a number of groupings that can be described as follows:
• Alkaline earth metal hydroxides and oxide-hydrates i.e., Mg(OH) 2 ; MgO - x H 2 0
• Alkaline neutralized salts of transition metals in water or other caustic media using Bronsted or non-Bronsted base to neutralize in-situ salts of Fe, Cr, Al, Zn, Cu, Ni, and others where the in-situ final product formed is a "hydrated" or carrier impregnated hydroxide of the metal that may also be called a hydrous-oxide;
• Modified Starches both synthetic and natural (i.e., such as corn starch and others)
• Cellulose derivatives such as, but not limited to: Hydroxy cellulose, Hydroxy propyl cellulose, Methyl carboxymethyl cellulose, Acetyl cellulose;
• Polyelectrolytes in non-ionic, polar organic carriers may include: Sulfonated polystyrene (PSS), Poly acrylic acid, methacrylic acid, maleic acid, or copolymers thereof (neutralized or partially neutralized) (PAA), Ammonium poly (methacrylate) (APMA), Poly ester amide and co-polymers of said Poly amines, Poly - (amino acid) polyelectrolytes, e.g., Poly (L-aspartic acid) (PAA), Poly (L-glutamic acid), (PGA) and Poly (L-Lysine) (PLL).
• PSS Sulfonated polystyrene
• PAA Poly acrylic acid, methacrylic acid, maleic acid, or copolymers thereof (neutralized or partially neutralized)
• APMA Ammonium poly (methacrylate)
• PLL Poly ester amide and co-polymers of said Poly amines
• gel particles for applications relevant to this invention all have many common properties, behavior and characteristic threads binding the vast diversity of structures, compounds, polymers and materials together. Regardless of formation mechanism or origin, all “gel particles”, as defined and described in the examples above, have the same common performance and behavioral properties required for the useful applications noted above.
• Polysaccharides have been used as coating compositions in an aqueous carrier.
• One such example of formation of a coating composition begins with the preparation of modified polysaccharides by suspending 5g of selected pure polysaccharides-agar and guar gum in 100 ml of distilled water. The suspensions were stirred at 500 rpm using a magnetic stirrer for 24 hours. The obtained swollen masses were spread out on enameled trays and dried at 40° C for 72 hours. The dried product was scrapped out of the trays and crushed in a glass pestle mortar to obtain coarse, non-free flowing heterogeneous particles of treated polysaccharides- treated agar and treated guar gum.
• the treated polysaccharides were then co-grinded with mannitol in a 1 :1 ratio in a glass pestle mortar for 20 minutes and passed through a #22 sieve to obtain the modified polysaccharides-co-grinded treated agar and co-grinded treated guar gum.
• the resulting product was then used as a gelatinous coating for pharmaceuticals for ingestion by humans.
• gel particles can be made by other means than just the mixing of appropriate compositions in liquid carriers, but still retain the properties and characteristics discussed in regard to this invention.
• Polysaccharides have also been used to form gelatinous particles to assist in the construction of foundation walls as a substitute to thicken water utilized to maintain the open trenches while preventing the water that is keeping the trenches from inward collapse from migrating into the soil.
• polysaccharides e.g., starch, guar, carboxymethylcellulose, sugar beet pulp derivative and hydroyethylcellulose, which have suitable viscosity and solvation properties
• the polysaccharide polymers have a long solvation time either when added to water as a powder or in the form of an oil-based slurry. This is an example of a different polymer being utilized either as a powder or as an organic slurry to form gel-particles for use in the main carrier system.
• Polyelectrolytes are "dipole" charged polymers capable of stabilizing (or destabilizing) colloidal emulsions through electrostatic interactions.
• the effectiveness of polyelectrolytes is dependent upon molecular weight, pH, solvent polarity, ionic strength, and the hydrophilic- lipophiiic balance.
• Polyelectrolytes are made up of positively or negatively charged repeat units. Polyelectrolytes become charged through the dissociation of monomer side groups. If a greater number of monomer side groups are dissociated, the resulting charge will be greater.
• the charge of the polymer classifies the polyelectrolyte as positive (cationic) or negative (anionic). It is the level of the charge and the ionic strength of the polyelectrolyte that dictates how thick a polyelectrolyte layer will be.
• gel-particle distribution in the carrier system in order to maintain separation between the gel particles and the added abrasive or inert particles.
• a test was conceived to determine whether gel-particle dilution would vary the effectiveness of the gel particles in preventing agglomeration of the added abrasive or inert particles in the slurry.
• a water-based aqueous solution with formed gel particles was prepared. All testing was performed at ambient temperature, 22° C, with a constant volume of 40 ml regardless of dilution factor.
• the following Table 7 shows the dilution factors with the Suspension Volume Retention [SVR] expressed as a % of the original suspension volume of 40 ml in a calibrated container.

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